systemic_group_3.lstystemic bacteriology

Group 3
• Group 3 members:
• SHBI/01112/2019 ACHIENG TERRY
• SHBI/01094/2017 OTIENO JULIUS
• SHBI/01086/2019 ALFRED NJIMA
• SHBI/00624/2017 VICTOR JOASH
• SHBI/01524/2018 SOLVAY MOKAYA
• SHBI/01102/2019 KIBET COLLINS
• SHBI/01118/2019 MONICAH OMONDI
• SHBI/01119/2019 APONDI COLLINS

Legionella
• Legionella pneumophila (and other legionellae) causes pneumonia, both in
the community and in hospitalized immunocompromised patients.
Important Properties
• Legionellae are gram-negative rods that stain faintly with the standard
Gram stain.
• They do, however, have a gram-negative type of cell wall, and increasing
the time of the safranin counterstain enhances visibility.
• Legionella pneumophila causes approximately 90% of pneumonia
attributed to legionellae. There are 16 serogroups of L. pneumophila, with
most cases caused by serogroup organisms.

Classification
Domain: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Legionellales
Family: Legionellaceae
Genus: Legionella

Morphology
• Gram-negative, rigid
• Shape: Legionella bacteria are typically rod-shaped (bacillus) and are
often described as being thin and elongated.Highly motile-single polar
flagella
• Size: Legionella bacteria are relatively small, with an average size of
about 2-5 micrometers in length and around 0.2-0.5 micrometers in width.
• Motility: Legionella bacteria are usually motile, possessing a single polar
flagellum or multiple flagella that enable them to move in water
environments
• Capsule: Some strains of Legionella may possess a capsule

Cultural Characteristics
• Selective Media:Buffered charcoal yeast extract (BCYE) agar is a commonly
used medium. BCYE agar contains nutrients such as yeast extract, amino
acids, and iron salts that support the growth of Legionella.
• L-Cysteine and Iron: Legionella species need L-cysteine (an amino acid) and
iron for proper growth.
• Temperature: Legionella species are mesophilic, meaning they thrive at
moderate temperatures. The optimal temperature for their growth is
around 35-37°C (95-99°F
• Colonies: Legionella colonies on BCYE agar are often grayish-white
to cream-colored, round, convex, and translucent.

• Incubation Period: Culturing Legionella species can take some time
due to their slow growth rate. Plates are typically incubated for about
3-7 days before being examined for bacterial colonies.
• Hemolysis: Some species of Legionella might exhibit hemolysis
(breaking down of red blood cells) when grown on blood agar, but
this is not a consistent characteristic among all Legionella species.
• Nutritional Requirements: In addition to L-cysteine and iron,
Legionella species have specific nutritional requirements for amino
acids, vitamins, and other compounds. Growth media are formulated
to meet these needs.

Biochemical Characteristics
• Catalase positive
• Oxidase positive
• Urease Negative
• Nitrate reduction
• Utilization of Amino acids
• Utilization of carbohydrates
• Esculin hydrolysis
• Indole production – Negative for indole production

Pathogenesis And Epidemiology
• Legionellae are associated chiefly with environmental water sources such as air
conditioners and water-cooling towers.
• Outbreaks of pneumonia in hospitals have been attributed to the presence of the
organism in water taps, sinks, and showers
• Legionellae can replicate to large numbers in free-living amebas in these water
sources.
• The typical canadidate for Legionnaires’ disease is an older man who smokes and
consumes substantial amounts of alcohol.
• Patients with acquired immunodeficiency syndrome (AIDS), cancer, or
transplants (especially renal transplants) or patients being treated with
corticosteroids are predisposed to Legionella pneumonia

Virulence factors
• Flagella and motility :
• Type IV Secretion System (T4SS): Legionella species possess a sophisticated type
IV secretion system, which allows them to inject effector proteins into host cells.
• Intracellular Replication: Legionella species have evolved to replicate within host
cells, primarily within phagocytes like macrophages
• LPS Modifications: Legionella species have lipopolysaccharides (LPS) on their
outer membrane, but the structure is modified compared to other Gram-negative
bacteria
• Iron Acquisition: Legionella species have evolved mechanisms to scavenge iron
from the host environment. This contributes to their ability to replicate within
host cells and evade immune responses.

Virulence factors
• Evasion of Phagosome-Lysosome Fusion: Legionella bacteria are able
to avoid being degraded within phagolysosomes by inhibiting
phagosome-lysosome fusion
• Phospholipase C: Some Legionella species produce phospholipase C,
an enzyme that hydrolyzes host cell membranes, allowing the
bacteria to escape from the phagosome and enter the host cell
cytoplasm
• Biofilm Formation: In aquatic environments, Legionella can form
biofilms on surfaces, providing protection from disinfection measures
and allowing the bacteria to persist and multiply

Laboratory Diagnosis
• Sample Collection: Respiratory samples, such as sputum, bronchoalveolar lavage
(BAL), or tracheal aspirates, are commonly collected from patients suspected of
having Legionella infections. Urine samples can also be tested for specific
antigens
• Sputum Gram stains reveal many neutrophils but no bacteria.
• The organism fails to grow on ordinary media in a culture of sputum or blood,
but it will grow on charcoal yeast agar, a special medium supplemented with iron
and cysteine.
• Polymerase Chain Reaction (PCR): PCR can amplify specific DNA sequences of
Legionella bacteria in clinical samples. It offers high sensitivity and specificity and
can provide rapid results

• Urinary Antigen Testing: Legionella pneumophila serogroup 1 is the
most common cause of Legionnaires' disease, and a urinary antigen
test specific to this serogroup can provide rapid diagnosis.
• Serological Testing: Serological tests measure antibody responses
against Legionella antigens in patient serum. A rise in antibody titers
between acute and convalescent samples can suggest a recent
infection.
• Next-Generation Sequencing (NGS): NGS techniques, such as whole-
genome sequencing (WGS), can provide detailed genetic information
about Legionella isolates.

Clinical Findings
• The clinical picture can vary from a mild influenza like illness to a
severe pneumonia accompanied by mental confusion, nonbloody
diarrhea, proteinuria, and microscopic hematuria.

Treatment
• Azithromycin or erythromycin (with or without rifampin) is the
treatment of choice.
• Certain fluoroquinolones, such as levofloxacin and trovafloxacin, are
also drugs of choice.
• These drugs are effective not only against L. pneumophila, but also
against Mycoplasma pneumoniae and Streptococcus pneumoniae.
• The organism frequently produces β-lactamase, and so penicillins and
cephalosporins are less effective.

Prevention
• Prevention involves reducing cigarette and alcohol consumption,
eliminating aerosols from water sources, and reducing the incidence
of Legionella in hospital water supplies by using high temperatures
and hyperchlorination.
• There is no vaccine.

Moraxella
• Moraxella is a genus of bacteria that belong to the family
Moraxellaceae. They are Gram-negative, aerobic, non-motile cocci or
coccobacilli. Moraxella species are commonly found in various
environments, including the human respiratory tract and other
mucous membranes, as well as in soil and water. Some species of
Moraxella are considered opportunistic pathogens and can cause
infections in humans, especially in immunocompromised individuals
or those with underlying health conditions

Classification
• Domain: Bacteria
• Phylum: Proteobacteria
• Class: Gammaproteobacteria
• Order: Pseudomonadales
• Family: Moraxellaceae
• Genus: Moraxella .
• This genus includes the species, Moraxella catarrhalis, M. oblonga, M. osloensis, M.
saccharolytica, M. phenylpyruvica, M. lacunata, M. lincolnii, M. nonliquefaciens, M. boevrei, M
.bovis, M. canis, M. caprae, M. caviae, M. cuniculi, and M. equi. Of these species, Moraxella
catarrhalis, M. lacunata, M. nonliquefaciens, M. osloensis, M. atlantae, and M. phenylpyruvica are
the most clinically significant.
• Animal-specific strains include M. bovis, M. canis, and M. caprae.

Morphology
• Shape: Generally coccobacilli (oval or elongated cocci).
• Cell Arrangement: Can occur singly, in pairs, or short chains.
• Size: Small, around 1-2 micrometers in diameter
• Cell Wall: Gram-negative, with an outer membrane containing
lipopolysaccharides (LPS).
• Capsule: Some species possess a capsule that surrounds the cell,
aiding in virulence and protection.
• Spores: Non-sporulating; does not form endospores
• Non motile

• Colonies on Agar: Moraxella colonies are often small, smooth,
and translucent. They can appear whitish or slightly yellowish.
• Growth Rate: Moraxella species tend to have a slow growth
rate compared to many other bacteria
• Nutritional Requirements: Moraxella are often considered
fastidious bacteria, meaning they have specific nutritional
requirements and may require enriched media or supplements
to grow well.
• Media Preference: Blood agar and chocolate agar are
commonly used media to culture Moraxella due to their
nutritional richness. The blood components in these media
provide essential growth factors

Hemolysis: Some Moraxella species, when grown on blood agar, may
exhibit β-hemolysis (complete lysis of red blood cells) or γ-hemolysis
(no hemolysis)
Selective Media: Thayer-Martin agar, a selective medium containing
antibiotics, can be used to isolate Moraxella species from clinical
samples, especially those containing mixed bacterial flora
Temperature and Atmosphere: Moraxella species generally grow
best at moderate temperatures (mesophilic) and in aerobic
conditions, although they can tolerate low levels of oxygen

Biochemical characteristics
• Gram-negative:
• Oxidase-positive:
• Catalase-positive:
• Non-motile:.
• Non-fermentative:.
• Indole-negative: .
• Glucose utilization:
• Nitrate reduction:
• Urease-negative:

Pathogenesis
1. Transmission: Moraxella bacteria are typically transmitted from
person to person through respiratory droplets when an infected
person coughs or sneezes. It can also spread by direct contact with
infected individuals or contaminated surfaces.
2. Attachment: Once the bacteria enter the respiratory tract of a
susceptible individual, they use their surface structures, like pili and
adhesins, to attach to the mucosal surfaces of the respiratory tract,
particularly the epithelial cells lining the airways and nasal passages.
3. Colonization: After attaching to the respiratory epithelial cells,
Moraxella bacteria start to multiply and form colonies, establishing
themselves in the host's respiratory tract.

Pathogenesis
3. Invasion and Damage: Moraxella catarrhalis can produce various virulence
factors, such as outer membrane proteins and toxins, which help them evade
the host's immune system and cause damage to the respiratory tissues. These
factors contribute to the inflammation of the respiratory tract, leading to the
characteristic symptoms of respiratory infections.
4. Immune Response: In response to the bacterial invasion, the host's immune
system activates various defense mechanisms, including the recruitment of
immune cells to the infected site, release of inflammatory mediators, and the
production of specific antibodies. However, Moraxella bacteria have developed
mechanisms to evade and resist these immune responses, allowing them to
persist and cause chronic infections in some cases.

Virulence factors
• Capsule: Some Moraxella species have a capsule that helps them
evade the host's immune system by preventing phagocytosis
• Pili/Fimbriae: Pili are hair-like structures on the bacterial surface that
facilitate adherence to host cells and surfaces
• IgA Protease: Some Moraxella species produce IgA protease enzymes
that can cleave and degrade immunoglobulin A (IgA), an antibody
class important in mucosal immunity
• Toxins: Certain Moraxella species can produce toxins that contribute
to tissue damage and inflammation

Virulence factors
• Lipopolysaccharides (LPS): The outer membrane of Moraxella
bacteria contains LPS, which can trigger inflammatory responses in
the host
• Adhesins: Apart from pili, other adhesins on the bacterial surface
facilitate binding to specific host cell receptors, enabling the bacteria
to colonize and establish infections
• Outer Membrane Proteins: Outer membrane proteins, including
porins, can contribute to the virulence of Moraxella species by aiding
in nutrient uptake, facilitating bacterial adhesion, and interacting with
host immune responses.

• Sample Collection: Obtain a clinical sample from the site of infection, which could
include sputum, conjunctival swabs, wound swabs, or other relevant specimens.
• Transport and Storage: Properly transport the sample to the laboratory using
appropriate transport media to maintain the viability of the bacteria during
transit.
• Microscopic Examination: Perform Gram staining of the sample to observe the
morphology and Gram reaction of the bacteria. Moraxella species are Gram-
negative cocci or coccobacilli.
• Culture: Inoculate the sample onto appropriate culture media. Chocolate agar or
blood agar are commonly used, as they provide the necessary nutrients for the
growth of Moraxella species.

• Incubation: Incubate the cultures at the appropriate temperature (usually around
35-37°C) and atmospheric conditions (usually aerobic).
• Isolation: After incubation, examine the cultures for colony growth. Moraxella
colonies are typically small, smooth, translucent, and often have a whitish or
yellowish appearance.
• Gram Stain of Colonies: Perform Gram staining on isolated colonies to confirm
their Gram-negative nature and verify their morphology.
• Biochemical Tests: Perform various biochemical tests to confirm the identity of
the isolated bacteria as Moraxella. These tests may include oxidase test (positive
for Moraxella), catalase test (positive), and other relevant metabolic tests.

• Antibiotic Sensitivity Testing: If the identified Moraxella
isolate is from a clinical specimen, antibiotic sensitivity testing
should be performed to guide appropriate treatment.
• Serological Tests: In some cases, serological tests may be
used to detect specific antibodies against Moraxella species in
patient serum.
• Molecular Methods: Polymerase Chain Reaction (PCR)
assays targeting specific Moraxella genes can provide rapid
and accurate identification of the bacteria.

Clinical Findings
1. Respiratory Tract Infections:
1. Acute Exacerbation of Chronic Bronchitis: Moraxella catarrhalis is a common cause of exacerbations in
chronic bronchitis patients, leading to increased cough, sputum production, and shortness of breath.
2. Sinusitis: Moraxella species can contribute to sinus infections, causing symptoms like facial pain, congestion,
and headache.
2. Conjunctivitis (Pink Eye):
1. Bacterial Conjunctivitis: Moraxella can cause bacterial conjunctivitis, resulting in redness, irritation,
discharge, and sometimes crusty eyelids.
3. Wound Infections:
1. Skin and Soft Tissue Infections: Moraxella species can lead to localized skin infections, maanifesting as
redness, swelling, pain, and sometimes the formation of pustules or abscesses.
4. Otitis Media:
1. Ear Infections: Moraxella catarrhalis can be a causative agent of otitis media (ear infections), causing ear
pain, fluid buildup, and hearing difficulties, especially in children.
5. Pneumonia:
1. Community-Acquired Pneumonia: In some cases, Moraxella species can contribute to community-acquired
pneumonia, with symptoms like fever, cough, chest pain, and difficulty breathing

Treatment
1.Antibiotics: Moraxella infections are typically treated with antibiotics. Commonly used
antibiotics include beta-lactams (such as amoxicillin-clavulanate), cephalosporins (such as
ceftriaxone), and macrolides (such as azithromycin). However, antibiotic choice should be
based on the specific species and its antibiotic susceptibility profile.
2.Antibiotic Sensitivity Testing: It's important to perform antibiotic sensitivity testing on
the isolated bacteria to determine which antibiotics are effective against the specific
strain. This helps in guiding appropriate treatment.
3.Duration of Treatment: The duration of antibiotic treatment varies depending on the
type and severity of the infection. Treatment for respiratory tract infections, for example,
might last for 7-14 days.
4.Follow-Up: Patients should complete the full course of antibiotics as prescribed by the
healthcare provider, even if symptoms improve before the course is finished

Prevention
1.Hygiene and Handwashing: Practicing good hygiene, including frequent handwashing,
can help prevent the spread of Moraxella bacteria and other pathogens.
2.Vaccination: For Moraxella catarrhalis, there is ongoing research into developing
vaccines, especially for conditions like otitis media and pneumonia. Vaccination could
potentially reduce the incidence of infections caused by this bacterium.
3.Avoiding Close Contact: In cases of contagious infections like conjunctivitis, avoiding
close contact with infected individuals can help prevent the spread of the bacteria.
4.Respiratory Etiquette: Practicing respiratory etiquette, such as covering the mouth and
nose when coughing or sneezing, can reduce the transmission of respiratory infections.
5.Infection Control: In healthcare settings, implementing infection control measures,
including proper sterilization of equipment and adherence to hand hygiene protocols, is
crucial to prevent the spread of Moraxella infections.

PSEUDOMONAS
• Pseudomonads are gram-negative and nonfermentative bacilli that are widely
distributed in nature as saprophytes or as commensals and pathogens for man.
• Gessard in 1882 isolated Pseudomonas aeruginosa.
• More than 100 species of Pseudomonads have been isolated so far. The most
frequently encountered species of Pseudomonas in humans is P. aeruginosa.
• This is a classical opportunist pathogen with innate resistance to many antibiotics
and disinfectants.
• It is invasive and toxigenic, produces infections in patients with abnormal host
defences and is an important nosocomial pathogen

Classification
• Order: Pseudomonadales
• Family: Pseudomonadaceae
• Genus: Pseudomonas
• Pseudomonas is a genus belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. This
genus includes many species of bacteria, the most important of which include:
• P. aeruginosa,P. alcaligenes,P. fluorescen,P. mendocina,P. putida,P. stutzeri

Morphology
• P.aeruginosa strains are gram-negative bacilli with variable length.
These measure 1.5-3.0 μm × 0.5 μm.
• These have parallel sides and rounded ends and are arranged singly,
in small bundles or short chains.
• The organism is motile with monotrichate flagellum. The cell wall and
other structural components are similar to other Gram negative
bacilli.
• Fimbriae present on P.aeruginosa differ from those on other gram-
negative bacilli in their inability to cause haemagglutination.

• P.aeruginosa is capable of growing in a wide range of temperature but optimal
growth occurs at 28°C. This organism can grow even at 41°C. pH below 4.5 is not
conducive for its growth. It is an obligatory anaerobic species.
• Clinical isolates grown on blood agar are frequently haemolytic
• On nutrient agar P.aeruginosa can produce three types of colonies which are 2-3
mm in diameter with a matt surface, a floccular internal structure and butyrous
consistency.
• Strains which are isolated from cases of cystic fibrosis are mucoid in nature and
produce copious amounts of extracellular polysaccharide on nutrient agar

Pigmentation on media
• Four types of pigments can be produced by P.aeruginosa strains.
i. Pyocyanin: It is a bluish -green phenazine pigment soluble in water and
chloroform. P. aeruginosa only produces this pigment, therefore this is a
diagnostic property of this bacterium.
ii. Pyoverdin:This pigment is a greenish yellow soluble in water but
insoluble in chloroform. other species can also produce this pigment.
iii. Pyorubin:This pigment is a reddish brown that is soluble in water and
insoluble in chloroform.
iv. Pyomelanin: It is a brown to black pigment. It is chemically unrelated to
melanin and its production is uncommon.

Biochemical Characteristics
• They are oxidative and nonfermentative.
• Glucose is utilized oxidatively.
• Indole, Methyl Red (MR) and VogesProskauer (VP) and hydrogen
sulphide (H2S) tests are negative.
• Catalase, oxidase, and arginine tests are positive.

Virulence Factors
• Pseudomonas aeruginosa has a number of virulence factors including:
i. Pili or fimbriae which mediate adherence to respiratory epithelium.
ii. Polysaccharide capsule which covered the bacterial surface to protect it from phagocytosis.
iii. Lipopolysaccharide endotoxin as a major cell antigen mediates the various biological effects
such as fever, shock, oliguria and leucopenia.
iv. Exotoxin A and exotoxin S which blocks or inhibition protein synthesis.
v. Elastase enzyme which destruction of the elastic fiber in blood vessel walls, resulting in
hemorrhagic lesions
vi. Protease enzyme that mediate tissue destruction, inactivation of antibiotics and inhibition of
neutrophils function.
vii. Phospholipids C that break down lipids and tissue destruction.

Pathogenesis and clinical picture
• Several exotoxins and enzymes produced by P.aeruginosa along with endotoxic cell wall and
fimbriae as well as occasionally a mucoid capsule probably account for the virulence associated
with this organism.
• The organism is so ubiquitous in wet hospital environment that some people prefer to call it as
water bug. In a hospital setting no open wound, burn or immunologically deficient patient is free
from exposure.
• The major body defence against Pseudomonas infection appears to be functioning phagocytic
system. In any condition which causes leukopenia, Pseudomonas assumes an opportunistic
pathogenic role.
• Several clinical conditions which are highly correlated with P.aeruginosa infection include cystic
fibrosis, burns, urinary catheterization, lumbar puncture and cancer chemotherapy. From any
such condition the patient may develop Pseudomonas pneumonia or bacteraemia

Pathogenicity of Pseudomonas
• They cause blue pus, causing the nosocomial infection, suppurative
otitis, localised and generalised infections, Urinary tract infection
(UTI) after catheterization, iIatrogenic meningitis, post tracheostomy
pulmonary infections etc.
• This bacterium is of particular concern to individuals with cystic
fibrosis who are highly susceptible to Pseudomonas lung infections. It
is also of grave concern to cancer and burn patients as well as those
people who are immuno-compromised.

• Diagnosis of P. aeroginosa infection depends upon isolation and laboratory
identification of the bacterium.
• It grows well on most laboratory media and commonly is isolated on blood agar
or eosin-methylthionine blue agar.
• It is identified on the basis of its Gram morphology, inability to ferment lactose, a
positive oxidase reaction, its fruity odour, and its ability to grow at 42°C.
• Fluorescence under ultraviolet light is helpful in early identification of P.
aeruginosa colonies.
• Fluorescence is also used to suggest the presence of P. aeruginosa in wounds

Treatment of P. aeruginosa
• The method of treatment employed by the clinicians depends on the severity of the infection.
• In the case of mild infections, courses of IV antibiotics are adequate enough for treatment;
however, under deeper infections, surgical debridement might also be required.
• In patients with respiratory failure, pneumonia, sepsis, or other systemic infections, ICU
admissions might be necessary.
• In addition to the broad-spectrum antibiotics, double pseudomonal coverage might also be
needed.
• Common antibiotics that are used as first-line therapy include carbapenems, cephalosporins,
aminoglycosides, and fluoroquinolones.
• In the case of systemic infections, longer exposure to medicinal therapy might be required. In
infections caused by medical devices like catheters, removal of such devices is done

Prevention and control
• Effective infection control practices should concentrate on prevention
of contamination of sterile equipment such as respiratory therapy
machines and cross - contamination of patients by medical personnel.
• The inappropriate use of broad spectrum antibiotics should be
avoided because this can suppress the normal flora and permit the
over growth of resistant Pseudomonas.
• Several types of vaccines are being tested, but none is currently
available for general use.

Classification
• Order: Pasteurellales
• Family: Pasteurellaceae
• Genus: Pasteurella

Classification
• Pasteurella belongs to the Pasteurellaceae family, which also includes the
genera Haemophilus and Actinobacillus. P. aerogenes, P. avium, P. bettyae, P.
canis, P. dagmatis, P. gallinarum, P. multocida, P. pneumotropica, P. stomatis,
P. testudinis, P. trehalosi, and P. volantium are the current species of
Pasteurella. P. multocida, P. canis, P. stomatis, and P. dagmatis are the most
frequent species in human infections.
• P. multocida has three subspecies: P. multocida subsp. gallicida, P.
multocida subsp. multocida, and P. multocida subsp. septica. Furthermore, P.
multocida strains are classified into serogroups A, B, D, E, and F based on
capsule antigenicity and serotypes 1–16 based on lipopolysaccharide
antigens.

Morphology
• Shape: Small, Gram-negative rods (bacilli).
• Arrangement: Usually appear singly or in pairs.
• Size: Generally, 0.3-0.5 μm in width and 1-2 μm in length.
• Cell Wall: Possesses a thin peptidoglycan layer in the cell wall, which contributes to its
Gram-negative staining.
• Capsule: Some strains may produce a capsule, contributing to virulence and immune
evasion.
• Motility: Non-motile.
• Spores: Non-spore forming.
• Flagella: Generally lack flagella, but some strains might have polar flagella for limited
motility.

Cultural characteristics
• Media: Pasteurella species are often grown on specialized media that
provide the necessary nutrients for their fastidious growth
requirements.
• Colonies: Colonies on agar plates are typically small, smooth, and
translucent or slightly opaque. The appearance can vary depending
on the species and strain.
• Hemolysis: Pasteurella species are generally non-hemolytic on blood
agar, meaning they do not cause complete destruction of red blood
cells in the agar medium.

Cultural characteristics
• Oxygen Requirements: These bacteria are facultative anaerobes, meaning they
can grow both in the presence and absence of oxygen. However, they generally
prefer environments with lower oxygen levels.
• Temperature: Optimal growth temperature can vary among species, but they
typically grow best at temperatures around 37°C (98.6°F), which is close to the
body temperature of their host animals.
• pH Range: The pH range for growth can vary, but it generally falls within the
neutral to slightly alkaline range.
• Selective Media: Due to their fastidious nature, Pasteurella species may require
selective media that provide specific nutrients to promote their growth while
inhibiting the growth of other organisms.

Biochemical characteristics
• Catalase and oxidase positive
• They do not ferment lactose
• Indole production ,Nitrate reduction, urease production and citrate
utilization is variable
• They are able to ferment glucose
• Hydrogen sulfide production, Gelatin Hydrolysis and Esculin
hydrolysis is variable

Virulence factors
• Capsule: helps the bacteria evade phagocytosis by host immune cells,
making it more difficult for the immune system to recognize and attack the
bacteria
• Lipopolysaccharides (LPS):initiate immune responses.
• Exotoxins: Some Pasteurella species produce exotoxins that can damage
host cells and tissues.
• Adhesins: Adhesins are surface molecules that allow Pasteurella bacteria
to bind to host cells and tissues
• Iron Uptake Mechanisms: Pasteurella species have mechanisms to acquire
iron from the host's environment

Virulence factors
• Hemolysins: While Pasteurella species are generally non-hemolytic on
blood agar, they can produce hemolysins that can damage host red
blood cells and contribute to tissue damage
• Resistance to Host Defense Mechanisms: Pasteurella species have
evolved mechanisms to resist host defense mechanisms, such as
phagocytosis by immune cells.
• Antigenic Variation: Pasteurella bacteria can undergo antigenic
variation, where they alter their surface antigens to evade host
immune responses

Pathogenesis
• Transmission: Pasteurella bacteria typically reside in the respiratory tracts of various animals, including cats,
dogs, rabbits, and birds.
• Entry and colonization: Pasteurella can enter the human body through breaks in the skin, such as wounds or
animal bites
• Local infection: Once Pasteurella establishes itself at the site of entry, it can cause localized infections such
as cellulitis, abscesses, or wound infections. The affected area may become red, swollen, and painful
• Systemic spread: In some cases, Pasteurella infections can progress to more severe systemic infections,
especially in individuals with compromised immune systems. Bacteria can enter the bloodstream and spread
to other parts of the body, leading to conditions like septicemia (bloodstream infection) or osteomyelitis
(bone infection).
• Immune response: The human immune system responds to the presence of Pasteurella by activating various
defense mechanisms, including the recruitment of immune cells to the infected area.

Clinical Features of Pasteurella
Skin and Soft Tissue Infections
• Commonly seen after animal bites or scratches.
• Rapid onset of redness, swelling, warmth, and pain at the site.
• May progress to localized abscess formation.
Cellulitis
• Infection spreads through the skin's deeper layers.
• Skin becomes tender, swollen, and may have a "peau d'orange" appearance.
• Fever and malaise can accompany severe cases.

Abscess Formation
• Accumulation of pus due to localized bacterial growth.
• Presents as a swollen, fluctuant, tender mass.
• May require surgical drainage for resolution.
Systemic Infections
• Bacteremia: Presence of bacteria in the bloodstream.
• Can lead to fever, chills, rapid heartbeat, and hypotension.
• Potentially life-threatening if not treated promptly.

Respiratory Tract Infections
• Seen in animals, less commonly in humans.
• Cough, nasal discharge, sneezing, and difficulty breathing.
• Pneumonia or bronchopneumonia can develop.
Osteomyelitis
• Infection of the bone, often due to direct inoculation.
• Presents with bone pain, swelling, and limited mobility.
• More common in cases of deep puncture wounds.

Septic Arthritis
• Infection of a joint, causing pain, swelling, and reduced range of motion.
• Often occurs following joint injury or surgery.
Endocarditis
• Infection of the heart's inner lining (endocardium).
• Fever, fatigue, heart murmur, and signs of heart failure.
Meningitis
• Rare complication of systemic spread.
• Severe headache, fever, neck stiffness, altered mental status.

Laboratory procedure for investigation
• Sample Collection: Collect samples from infected sites, such as
wounds, respiratory secretions, or blood.
• Culture: Inoculate the samples onto appropriate culture media like
blood agar or MacConkey agar. Pasteurella species are fastidious and
may require specific growth conditions
• Identification: Use biochemical tests or commercial identification
systems to confirm the presence of Pasteurella. Common tests
include oxidase, catalase, and indole tests
• Gram Stain: Perform a Gram stain to observe the bacteria's
morphology and Gram reaction.

Laboratory procedure for investigation
• Serotyping: Some Pasteurella species can be serotyped using specific
antisera to identify variations.
• Molecular Techniques: Polymerase chain reaction (PCR) and DNA
sequencing can be employed for accurate species identification.

Treatment
• Antibiotics: Antibiotics are the mainstay of treatment. Choice based on
bacterial susceptibility testing. Commonly used antibiotics include Penicillin
(e.g., amoxicillin-clavulanate),Cephalosporins (e.g.,
ceftriaxone),Fluoroquinolones (e.g., ciprofloxacin),Combination therapy
considered for severe infections.
• Supportive Care: Manage symptoms such as fever and pain, Adequate
hydration and nutrition.
• Surgical Intervention:
• Drain abscesses: Removal of pus to relieve pressure and aid healing.
• Debridement: Surgical removal of infected tissue to prevent spread.
• Especially important for deep tissue or systemic infections.

Treatment
1.Antibiotic Prophylaxis
1.Consider prophylactic antibiotics for high-risk animal bites or
scratches.
2.Especially important if the wound is deep, contaminated, or involving a
joint.
2.Tetanus Vaccination
1.Ensure up-to-date tetanus vaccination, especially for deep or puncture
wounds.
2.Tetanus booster recommended every 10 years.
3.Prompt Medical Attention
1.Seek medical care promptly after an animal-related injury.
2.Early treatment can prevent infection and complications.

Treatment
4. Animal Contact Awareness
1.Educate individuals about the risks of animal bites and scratches.
2.Encourage caution when interacting with animals, especially unfamiliar
ones.
5.Proper Animal Handling
1.Teach safe methods for handling pets and animals.
2.Avoid provoking animals that might lead to aggressive behavior.
6.Wound Care
1.Thoroughly clean and disinfect animal-related wounds immediately.
2.Wash wounds with soap and water to remove bacteria.

History
The genus Neisseria is named after the German bacteriologist Albert
Neisser, who in 1879 discovered its first example, Neisseria
gonorrhoeae, the pathogen which causes the human disease
gonorrhea.
Neisser also co-discovered the pathogen that
causes leprosy, Mycobacterium leprae. These discoveries were made
possible by the development of new staining techniques which he
helped to develop.

Classification
• Kingdom- monera
• Phylum-protobacteria
• Class- betaproteobacteria
• Order-neisseriales
• Family-Neissriaceae
• Genus- Neisseria
• Species- species of clinical significance; gonorrhoea, meningitidis

Morphology
Are gram negative
Diplococci- occurs as two joined cells
Non-motaile: lack flagella
Do not produce spores
Have capsule (N. meningitidis) N. gonorrhoea
lack capsule

Cultural characteristics: N. gonorrhoea
N. gonorrhoeae is a fastidious coccus
It requires complex media for growth: These cannot grow on
ordinary media
They are aerobes but can also grow anaerobically.
They grow optimally at a temperature range of 35–36°C. They fail to
grow at temperature less than 25°C or greater than 37°C.
The growth of bacteria is enhanced by incubation in humid
atmosphere supplemented with 5–10% CO2 concentration

Cultural morphology: on Blood agar
• N. gonorrhoeae produces convex small colonies
• These colonies are translucent with entire edges and finely granular
surface.

Selective media
Thayer Martin medium : its chocolate agar medium containing
antibiotics, such as colistin, nystatin, and vancomycin
Modified New York City medium: its a translucent medium
containing vancomycin, colistin, trimethoprim, and either nystatin or
amphotericin B
• These selective media are used for isolation of gonococci from the
clinical specimens containing mixed microbial flora.
• On these media, N. gonorrhoeae produces small, translucent, and
convex colonies, which are soft and easily friable

Transport media
• Stuart’s transport medium is used for the collection and transport of
clinical specimens to the laboratory for isolation and demonstration
of N. gonorrhoeae

Biochemical characteristics of Gonococci
Gonococci ferment glucose with the production of acid but no gas.
 They do not ferment maltose, lactose, sucrose, or fructose. This is an
important feature to differentiate N. gonorrhoeae from N.
meningitidis. N. gonorrhoeae utilizes glucose only, whereas N.
meningitidis utilizes both glucose and maltose.
They do not reduce nitrates,
 They do not produce hydrogen sulfide (H2S).
Oxidase positive
Catalase positive.

Morphology of N.meningitidis
Are Gram-negative
They are spherical, or oval cocci arranged in pairs with the adjacent
sides flattened.
They measure 0.6–0.8 um in diameter.
Freshly isolated bacteria are usually capsulated (have a capsule).
They are non-motile (lack flagella)
Non-sporing (do not produce spores)

Biochemical characteristics of N.meningitidis
Oxidase positive
Catalase positive
• These two tests are important biochemical markers for preliminary
identification of this organism.
N. meningitidis ferments glucose and maltose with acid but no gas.
It does not ferment sucrose or lactose.
It does not produce hydrogen sulphide
Does not reduce nitrate to nitrite.

Cultural characteristics of N.meningitidis
meningococci are strict aerobes (they grow and survive only in the
presence of oxygen)
They grow optimally at a temperature between 36°C and 39°C.
optimum pH of 7.4–7.6.
Their growth is enhanced by incubation in a moist atmosphere in
the presence of 5% CO2 concentration .
Meningococci are fastidious bacteria with complex nutritional
requirements.

Blood agar
N. meningitidis produces small, round (1–2 mm in diameter), convex,
gray, and translucent nonpigmented colonies with entire edges after
24 hours of incubation.
It does not produce any hemolysis on blood agar. Strains of
meningococci with large polysaccharide capsule appear as mucoid
colonies.
Meningococci produce large colonies on chocolate agar.

Selective media
Thayer Martin medium with antibiotics (vancomycin, colistin,
nystatin, and trimethoprim)
New York City medium are the selective media commonly used for
the isolation of the bacteria from clinical specimens containing mixed
bacterial flora.
N. meningitidis should appear as large, round, smooth, convex,
colorless-to-grey, opaque colonies on the Thayer Martin medium
with no discoloration of the medium.

Pathogenesis: N. gonorrhoea
Virulence factors
Capsule- Prevents phagocytosis
Pili- Mediate attachment of gonococci to nonciliated epithelial cell;
prevent ingestion and killing of gonococci by neutrophils
Por proteins- Confer resistance to serum killing of gonococci by
preventing fusion of phagolysome in neutrophils
Opa proteins- Mediate bacterial adherence to each other, and to
the eukaryotic cells

Virulence factors (continued…)
Rmp proteins- Produce antibodies that block serum bactericidal
activity against gonococci
Lipo-oligosaccharide (LOS)- Possesses endotoxic activity of the
bacteria
IgA protease- Destroys IgA immunoglobulin
Beta-lactamase- Degrades beta-lactam rings in the penicillin
Plasmids- Plasmid-borne virulence determinants are associated with
antimicrobial resistance

Clinical diseases
•Gonorrhea
Gonorrhea is a sexually transmitted disease. It is
primarily a genital infection restricted to the
urethra in men and cervix in women. The
incubation period varies from 2 to 8 days.

Gonorrhea in men
Asymptomatic acute infection is seen in approximately 95% of all
infected men.
Urethritis is the major clinical manifestation, with
• burning urination (micturition) and
• serous urethral discharge as the initial manifestation
Subsequently, the discharge becomes more profuse,
purulent(containing pus), and even blood-tinged.
Acute epididymitis, prostatitis, and peri-urethral abscess are rare, but
are noted gonococcal complications in men.

Gonorrhea in women
In women, endocervix is the primary site (80–90%) of infection
because gonococci invade only the endocervical columnar epithelial
cells.
The infection is mostly asymptomatic in women.
Symptoms
• The presence of vaginal discharge,
• Dysuria (Pain or burning sensation while passing urine)
• Dyspareunia(painful sexual intercourse)
• mild lower abdominal pain
• In 10–20% of infected women, the primary infection may spread

Disseminated gonococcal infections(DGI)
• (DGI) occurs because of hematogenous dissemination of gonococci from the
primary site of infection.
Arthritis-dermatitis syndrome is the classic presentation of DGI. Joint or tendon
pain is most common in the early stage of infection.
Migratory polyarthrititis, especially of the knees, elbows, and more distal joints,
and also tenosynovitis are the common symptoms.
Skin lesions include maculopapular to pustular lesions often with a hemorrhagic
component. Septic arthritis, especially of the knee, is the next stage of DGI.
NOTE: The DGI is mostly seen in untreated asymptomatic women and in persons
with complement deficiency.

Ophthalmia neonatorum
• It’s a non-sexually transmitted infection caused by N. gonorrhoeae.
This is a condition of bilateral conjunctivitis of a neonate born by vaginal
delivery to an infected mother. However, transmission to the newborn can
also occur in utero or in the postpartum period.
The common symptoms are pain in the eyes, redness, and purulent
discharge . Blindness is a complication of this condition.

Pathogenesis: N.meningitidis
Virulence factors
Capsule- Prevents phagocytosis
LOS endotoxin- Causes damage of the blood vessels associated with
meningococcal infections
IgA protease- Destroys IgA immunoglobulin, thereby helps gonococci
to attach to the epithelial cells of the upper respiratory tract
Lipo-oligosaccharides- Stimulates release of TNF-a, which results in
host cell damage

Meningitis
• N. meningitidis colonizes the human nasopharynx, and under specific conditions, invades the
blood stream and then reaches the brain, causing meningitis.
• Meningococcal meningitis caused by N. meningitidis is most common in children and young
adults.
• It is a febrile illness of short duration characterized by:
 Headache and stiff neck. Lethargy or drowsiness is frequent.
Confusion, agitated delirium, and stupor are rarer.
Mental obtundation: its mild to moderate alertness reduction (altered level of consciousness)
with decreased interest in the environment and slower than normal reactivity to stimulation.
Stupor(state of near unconsciousness) and coma due to increased intracranial pressure are some
of the noted complications at the end stage of the disease.

Meningococcemia
• it’s a blood infection caused by the bacterium Neisseria
meningitidis, also called meningococcus
• The condition presents as: an acute fever with petechial rash.
• Small petechial rashes (these pinpoint red dots on the skin are caused
by broken capillaries) are continuously found on the trunk and lower
extremities; subsequently the rashes may coalesce to form large
hemorrhagic lesions.

Meningococcemia
Non-suppurative arthritis, usually of the knee joint, is seen in
approximately 10% of the patients with meningococcal disease.
This condition is observed within the first 48 hours of treatment and is
believed to be immunologically mediated.
 Recurrent meningococcal meningitis is another condition which is
associated with hereditary deficiency of various components of
complement system.
 Other conditions include meningococcal pneumonia (which probably
results from the aspiration of the organisms), septic arthritis, purulent
pericarditis, and endophthalmitis

Laboratory diagnosis of N. gonorrhoeae
• Specimen:
 urethral discharge in males
 cervical discharge in females are the specimens of choice.
 High vaginal swab in females

Specimen processing
Culture and isolation
culture confirms the diagnosis of gonorrhea. Genital, rectal, and pharyngeal specimens
are inoculated on a nonselective medium (e.g., blood agar or chocolate agar) and on a
selective medium (e.g., Modified Thayer Martin medium).
The colonies of gonococci on chocolate agar are small, round, translucent, and convex
with finely granular surface. On Thayer Martin medium, the colonies show similar
morphology as that on chocolate agar.

Microscopy
• Gram stain of urethral exudates: The presence of four or more
polymorphonuclear (PMN) leukocytes per oil-immersion field in
Gram-stained urethral exudate smear is diagnostic of urethritis:

Detection of gonococcal antigen
• The gonococcal antigens can be detected by both direct fluorescent
antibody (DFA) test and direct enzyme-immunoassays (EIA) in urethral
discharge and endocervical discharge as well as in other clinical
specimens.
The DFA using fluorescein-conjugated monoclonal antibodies is a rapid and
useful method for demonstration of gonococcal antigens in clinical
specimens.
The EIA using polyclonal antigonococcal antibodies are also used for the
detection of gonococcal antigens in clinical specimens

Serodiagnosis
• The serological tests are done to detect gonococcal antigens or
specific anti-gonococcal antibodies in the serum for diagnosis of
gonorrhea.
• ELISA and RIA (radioimmunoassays) using whole cell lysates, pilus
proteins, and LPS antigens of the gonococci demonstrate antibodies
in the serum.
• NOTE: These serological tests are not recommended for routine use.
These are used only in specific situations, such as chronic
gonorrhea, gonococcal arthritis, etc

Treatment and control
CDC recommends a single dose of 500 mg of intramuscular
ceftriaxone.
Alternative regimens are available when ceftriaxone cannot be used
to treat urogenital or rectal gonorrhea.
Although medication will stop the infection, it will not repair any
permanent damage done by the disease.

Diagnosis of N.meningitidis infection
• Specimen
Cerebrospinal fluid and blood are the specimens of choice for
demonstration of meningococci in the early stage of meningitis.
Nasopharyngeal swabs are useful to detect carriers.
NB: The CSF is collected by lumbar puncture and blood by venipuncture
in strict aseptic conditions. CSF is never refrigerated as Haemophilus
influenzae, another agent of meningitis, may die at the cold
temperature.

Microscopy Gram staining
Microscopy Gram staining of the CSF is a very useful method for
detection of meningococci. Meningococci are seen as Gram-negative
diplococci present mainly inside the leukocytes and some may even
be present extracellularly.
 These cocci can be demonstrated in the CSF in approximately 50% of
the patients with meningococcal meningitis. In fulminant
meningococcemia, Gram staining of the peripheral blood buffy coat
may reveal Gram-negative diplococci.

Culture and Isolation
N. meningitidis can be isolated from the CSF, blood, and other clinical specimens
by culture confirms the diagnosis of meningococcal infection.
The CSF is inoculated immediately on a nonselective medium, such as blood agar
or chocolate agar, and incubated at 35–36°C under 5% CO2 for 18–24 hours. The
colonies of meningococci are small, round, translucent, and convex with a
smooth glistening surface. Blood is inoculated immediately into blood culture
bottles containing either glucose broth or sodium taurocholate broth and
incubated at 35–36°C.
Subcultures are made on blood agar or chocolate agar from these broths and are
re-incubated overnight at 35–36°C in the presence of 5% CO2 . The cultures
should be incubated for 4–7 days with daily subculture. Blood culture is often
positive during early stage of meningitis and in meningococcemia.

Antigen detection
Detection of soluble polysaccharide antigen in the CSF is a useful
method for diagnosis of meningococcal meningitis. Counter-current
immunoelectrophoresis, latex agglutination test, and bacterial
coagglutination test using specific antibodies are the rapid tests
frequently used to detect the soluble antigen in the CSF.
Antigen detection is useful when bacteria are scanty in the CSF.
However, antigen detection is not useful in the meningitis caused by
Group B meningococci because N. meningitidis serogroup B is
relatively non-immunogenic and does not react with specific
antibodies

Serological tests
• Serodiagnosis Indirect hemagglutination test and ELISA are useful for
the demonstration of antibodies against specific polysaccharide
antigen in the serum. Serodiagnosis is useful in the cases of chronic
meningococcal infection where cultures have proved negative for
meningococci

Treatment of meningococcal infection
• Antimicrobial chemoprophylaxis of close contacts is the key factor for
preventing secondary cases of sporadic meningococcal disease.
• Sulfonamides, rifampin, minocycline, ciprofloxacin, and ceftriaxone
are the drugs frequently used to eradicate meningococci from the
nasopharynx. However, ciprofloxacin is not recommended for
children, because it has been found to cause cartilage damage in
immature experimental animals.

Prevention
Immunoprophylaxis by vaccination is very much useful for prevention
of meningococcal disease.
You can prevent meningitis from spreading by washing your hands
vigorously, especially after you use the bathroom, change a diaper,
spend time in a crowded place, and cough or blow your nose

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