Micro SOLO 7 Review

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Questions and Answers

What is the primary habitat for Bartonella baciliformis?

Humans (correct)

Domestic cats

Fleas

Sandflies

Which symptom is associated with Carrion's disease caused by Bartonella baciliformis?

Papule at the inoculation site

Bacteremia

Wart-like lesion called a verrugo (correct)

Regional tender lymphadenopathy

What is a significant virulence factor of Bartonella species?

Ability to survive in dry conditions

Induction of endothelial cell apoptosis

Colonization of vascular endothelium (correct)

Multiplies and persists in neutrophils

How is Bartonella henselae primarily transmitted?

Domestic cat bites or scratches Signup and view all the answers

What is the characteristic appearance of colonies from the Bartonella genus when cultured?

Slow growth on BAP after 12 to 14 days Signup and view all the answers

Which of the following factors is essential for the growth of Haemophilus species?

V factor – Nicotine adenine dinucleotide Signup and view all the answers

What is the primary agar used to cultivate Haemophilus species due to its nutritional components?

Chocolate agar Signup and view all the answers

Which diseases are commonly associated with Haemophilus ducreyi?

Chancroid and genital lesions Signup and view all the answers

What unique phenomenon allows Haemophilus species to grow on blood agar plates?

Growth alongside Staphylococcus aureus Signup and view all the answers

How is Haemophilus ducreyi primarily transmitted among individuals?

Person-to-person contact through sexual activity Signup and view all the answers

What type of cellular morphology do members of the Haemophilus genus exhibit?

Small, nonmotile, pleomorphic gram-negative bacilli Signup and view all the answers

Which identification medium for Haemophilus ducreyi includes vancomycin to suppress gram-positive bacteria?

Mueller Hinton with 1% IsoVitaleX Signup and view all the answers

What characteristic of Staphylococcus aureus causes the satellite phenomenon?

Capable of lysing red blood cells Signup and view all the answers

What is the primary characteristic of Haemophilus ducreyi colonies?

They can be pushed intact across the agar surface. Signup and view all the answers

Which factor is required for the growth of Haemophilus ducreyi?

X factor only Signup and view all the answers

What is the recommended treatment for infections caused by Haemophilus ducreyi?

Erythromycin Signup and view all the answers

What differentiates Haemophilus haemolyticus from Haemophilus influenzae in identification?

Haemophilus haemolyticus is beta-hemolytic. Signup and view all the answers

Which virulence factor is associated with encapsulated strains of Haemophilus influenzae?

Antiphagocytic properties Signup and view all the answers

What fermentation activity is NOT observed in Haemophilus ducreyi?

Sucrose fermentation Signup and view all the answers

What infection is commonly associated with encapsulated strains of Haemophilus influenzae?

Meningitis Signup and view all the answers

What is one characteristic of Haemophilus influenzae unencapsulated strains?

Small and smooth Signup and view all the answers

What is a common resistance pattern found in Haemophilus influenzae?

Beta-lactamase-mediated resistance Signup and view all the answers

What is the primary mode of transmission for Haemophilus influenzae?

Endogenous strain Signup and view all the answers

What is the primary route of human infection by Brucella species?

Ingestion of unpasteurized animal milk Signup and view all the answers

Which of the following diseases is mainly caused by Legionella pneumophila?

Legionnaires' disease Signup and view all the answers

What characteristic distinguishes Brucella species from other organisms?

They require CO2 for growth Signup and view all the answers

Which antimicrobial is NOT recommended for the treatment of Legionella pneumophila infections?

Aminoglycosides Signup and view all the answers

What is the result of the urea breath test when Helicobacter pylori is present?

Increased ammonia and labeled bicarbonate exhalation Signup and view all the answers

Which of the following is NOT a preferred animal host for Brucella species?

Cats Signup and view all the answers

What type of media is essential for the growth of Legionella pneumophila?

Buffered charcoal yeast extract (BCYE) with L-cysteine Signup and view all the answers

How is Helicobacter pylori typically identified in biopsy specimens?

With a rapid urease test Signup and view all the answers

Which of the following is true about the virulence factors of Brucella species?

They replicate inside neutrophils Signup and view all the answers

Which of the following symptoms is NOT commonly associated with brucellosis?

Severe dehydration Signup and view all the answers

Which test can be used for the direct identification of Legionella pneumophila in respiratory specimens?

Direct immunofluorescent antibody test Signup and view all the answers

Which of the following is NOT an effective treatment regimen for Helicobacter pylori?

Single agent metronidazole Signup and view all the answers

What is the primary form in which tularemia presents when associated with lymphadenopathy and ulcers?

Ulceroglandular tularemia Signup and view all the answers

Which antibiotic is considered the drug of choice for treating tularemia?

Streptomycin Signup and view all the answers

What is a common transmission route for Streptobacillus moniliformis to humans?

Direct contact with infected animals Signup and view all the answers

What characteristic morphology can Streptobacillus moniliformis exhibit under a microscope?

Long, tangled chains or filaments Signup and view all the answers

Which type of tularemia is considered the most serious form, often acquired through inhalation?

Pneumonic tularemia Signup and view all the answers

Which statement about the antimicrobial susceptibility of Francisella tularensis is true?

Development of antibiotic resistance is rare. Signup and view all the answers

Which symptom is typically associated with rat-biter fever caused by Streptobacillus moniliformis?

Joint pain Signup and view all the answers

What characteristic of Francisella tularensis colonies can be observed during isolation?

Transparent and mucoid colonies Signup and view all the answers

What complicating condition can arise from a Streptobacillus moniliformis infection?

Endocarditis Signup and view all the answers

Which of the following accurately describes the epidemiology of Streptobacillus moniliformis?

Associated with wild and laboratory rats. Signup and view all the answers

In the context of bioterrorism agents, which bacteria is classified as a Category A agent?

Francisella tularensis Signup and view all the answers

Study Notes

Haemophilus Species

Small, nonmotile, gram-negative bacilli
Typically coccobacillary or short rods
Need X factor (hemin) and/or V factor (NAD or NADP) to grow
Chocolate agar is the best medium for Haemophilus species, BAP lacks V factor
Satellite phenomenon when Staphylococcus aureus grows alongside Haemophilus on BAP: Staphylococcus breaks down red blood cells releasing X and V factors for Haemophilus to utilize

Haemophilus ducreyi

Not part of normal human flora
Transmitted person-to-person through sexual contact
Causes chancroid: genital lesions progress from papules to painful ulcers
Regional lymphadenitis is common
Grow on Mueller Hinton, BHI, and chocolate agar
Colonies are small, smooth and can be pushed intact across the agar surface ("hockey puck")
Requires X factor, but not V factor
Non-hemolytic, catalase negative, variable glucose fermentation, negative xylose, sucrose, and mannose fermentation

Haemophilus haemolyticus

Part of the normal human flora of the upper respiratory tract
Transmitted by patient's own strain
Colonies resemble H.influenzae on CAP, but beta-hemolytic on rabbit or horse blood agar
Requires both X and V factor for growth
Beta-hemolytic, catalase positive, glucose fermentation positive, variable xylose fermentation, negative sucrose and mannose fermentation

Haemophilus influenzae

Part of the normal human flora of the upper respiratory tract
Transmitted person to person contact, respiratory droplets, patient's own strain
Encapsulated strains are antiphagocytic and cause serious infections like: meningitis, epiglottitis, cellulitis, septic arthritis, and pneumonia.
Unencapsulated strains cause localized infections like: otitis media, sinusitis, and conjunctivitis.
Haemophilus influenzae type b causes the most serious infections.
Unencapsulated strains are small, smooth, and translucent, while encapsulated strains are larger and mucoid
Colonies have a distinct mouse nest odor
Requires X and V factors to grow
Non-hemolytic, catalase positive, glucose and xylose fermentation positive, sucrose and mannose fermentation negative

Bartonella Species

Grow on CAP but very slowly on BAP, do not grow on MAC
Colonies appear after 12 to 14 days, sometimes up to 45 days.
Short, gram-negative, pleomorphic rod-shaped
Oxidase and catalase negative

Bartonella bacilliformis

Only found in humans
Transmitted via sandflies
Causes Oroya fever: acute hemolytic bacteremia or a chronic vasoproliferative disease
Causes Carrion's disease: Produces a wart-like lesion called a verrugo.
Mortality rate is 40-90% dependent on the host and disease presentation

Bartonella henselae

Found in domestic cats
Transmitted by cat bites or scratches, fleas, and ticks
Causes bacteremia, endocarditis, bacillary angiomatosis
Causes Cat Scratch Disease (CSD), rheumatic manifestations, bacillary peliosis hepatitis
22,000 cases of CSD, 80% in children
Associated with infection beginning as a papule or pustule at the primary inoculation site, developing into regional tender lymphadenopathy in 1-7 weeks.

Helicobacter pylori

Found in the stomach
Transmitted person-to-person through fecal-oral route (Most common)
Transmitted by saliva (Less common)
Infects and persists in the gastric epithelium
Causes gastritis, peptic ulcers, gastric cancer, and MALT lymphoma
Positive for oxidase and urease

Campylobacter jejuni

Transmitted through consumption of contaminated food or water
Causes gastroenteritis, severe gastroenteritis, and bacteremia
Susceptible to many antimicrobial agents, including macrolides, tetracyclines, aminoglycosides, and quinolones
Increasing resistance to fluoroquinolones

Legionella pneumophila

Obligate aerobe, grows best between 20-45°C
Faintly staining, thin gram-negative bacilli
Does not grow on routine media, requires iron and L-cysteine for growth
Utilizes proteins for energy instead of carbohydrates
Found in aquatic habitats, primarily in warm water and man-made facilities
Survives up to 14 months in water
Transmitted through inhalation of aerosols from contaminated sources, NOT person-to-person
Legionella can multiply within amoebae and certain host cells, as well as within biofilms
Causes Legionnaires’ disease: Severe pneumonia with 10-20% fatality rate
Causes Pontiac Fever: Mild, self-limited, nonfatal, influenza-like respiratory infection
Can also cause extra-pulmonary infections
Definitive identification requires specialized laboratory testing
Growth is presumptively identified by growth on BCYE with L-cysteine
Direct immunofluorescent antibody (DFA) can be used on respiratory secretions to detect Legionella pneumophila

Brucella Species

Small, facultative intracellular, nonmotile, aerobic, gram-negative coccobacilli
Require CO2 for growth
Potential bioterrorism agents
Grow on BAP and CAP, require special media and conditions for optimal recovery
Blood culture systems are used to facilitate growth

Brucella abortus

Found in cattle and buffalo
Infects humans through consumption of unpasteurized milk, inhalation of infected aerosols, direct contact, and mucosal inoculation
Causes brucellosis: Systemic infection that can involve any organ in the body
Symptoms: Fever, chills, weight loss, night sweats, headache, muscle aches, fatigue, depression, lymphadenopathy, and splenomegaly
Small, convex, smooth, translucent, gamma hemolytic, slightly yellow colonies that brown with age after 48 hours of incubation
Catalase positive, urease positive, oxidase positive, 2 hours for positive urease, H2S produced, inhibited by thionine, not inhibited by fuchsin

Brucella melitensis

Found in sheep, goats, and camels
Most virulent Brucella species in humans
CO2 not required for growth
2 hours for positive urease, H2S negative, not inhibited by any stains

Brucella suis

Found in swine and wild animals
CO2 not required for growth
15 minutes for positive urease, variable H2S production, not inhibited by thionine, inhibited by fuchsin

Brucella canis

Found in dogs
CO2 not required for growth
15 minutes for positive urease, H2S not produced, not inhibited by thionine, inhibited by fuchsin
Colonies are rough instead of smooth

Bordetella Species

Nonmotile and infect only humans
Do not grow on MAC
Bordetella pertussis and Bordetella parapertussis

Tularemia

Lymph nodes near the inoculation site are enlarged and necrotic.
Patients become ill systemically once the organism enters the bloodstream.
Tularemia varies in severity from mild and self-limiting to fatal.
There are six distinct types of Tularemia.
Types of Tularemia
- Ulceroglandular tularemia: Common with ulcers and lymphadenopathy.
- Glandular tularemia: Common with lymphadenopathy.
- Oculoglandular tularemia: Conjunctivitis and lymphadenopathy.
- Oropharyngeal tularemia: Ulceration in the oropharynx.
- Systemic (typhoidal) tularemia: Acute with septicemia. It does not involve ulcers or lymphadenopathy.
- Pneumonic tularemia: Acquired by inhaling infectious aerosols or spreading from the bloodstream - the most serious form of tularemia.

Identification of Francisella tularensis

Colonies appear transparent and mucoid.
Isolates should be sent to a reference lab for confirmatory testing and characterization.
Possible indications of a Francisella tularensis isolate:
- Unusual gram stain with small, poorly staining gram-negative rods. These rods might appear as single cells or an amorphous gram-negative mass without distinct cell forms.
- Subcultures mainly yield pinpoint colonies on cysteine-heart agar (CAP). It grows better on CAP than blood agar (BAP).
- Oxidase negative.
- Weak catalase positive.
- Small gram-negative rods observed in a positive blood culture where detection time exceeds 24 hours.

Antimicrobial Susceptibility Testing for Francisella tularensis

No standardized susceptibility test exists.
Streptomycin is the primary treatment.
Gentamycin is a potential alternative.
Fluoroquinolones show promise for treating severe tularemia.
Antibiotic resistance development is rare.

Streptobacillus moniliformis: General Characteristics

It is a gram-negative bacillus that requires media containing blood, serum, or ascites fluid.
It also needs incubation under CO2 for isolation.
Considered a facultative anaerobe, exhibiting high pleomorphism.

Epidemiology of Streptobacillus moniliformis

Its natural habitat is the upper respiratory tract of wild and laboratory rats.
It has been isolated from other animals, including mice, gerbils, squirrels, ferrets, and weasels, after these animals have consumed rodents.
Isolated from cats and dogs that fed on rodents.
It is pathogenic to humans and is transmitted through two routes:
- Rat bite, or direct contact with rat feces or saliva.
- Ingestion of contaminated food, such as unpasteurized milk.
It occurs globally.

Virulence Factors and Spectrum of Disease for Streptobacillus moniliformis

While the virulence factors are unknown, it is known to spontaneously develop L forms, which are bacteria without cell walls, allowing them to persist.
The disease state is called rat-bite fever or Haverhill fever.
Patients develop acute onset of chills, fever, headache, vomiting, and often severe joint pains.
Symptoms typically occur within 3-10 days after exposure.
Patients may develop a rash on the palms, soles of the feet, and other extremities.
Other complications can include endocarditis, septic arthritis, pneumonia, pericarditis, brain abscesses, prostatitis, and pancreatitis.

Identification of Streptobacillus moniliformis

Streptobacillus moniliformis is a pleomorphic gram-negative rod
- Cells can appear straight, variable in size, or as long, tangled chains and filaments with bulbar swellings.
- It can resemble a string of pearls.
Growth on BAP can occur after 48 hours of incubation at 37°C.
Colonies embed in the agar, exhibiting a “fried egg” appearance with a dark center and a flattened, lacy edge.
- These colonies typically transform into the L form, and a gram-stain will reveal bi-polar staining coccoid forms.
- Acridine orange might be used to confirm the presence of bacteria, as a gram-stain heavily relies on the bacterial cell wall.
Indole Negative.
Catalase Negative.
Oxidase Negative.
Nitrate reduction Negative.
Nonmotile.
Urea Negative.
Lysine decarboxylase Negative.
H2S is not produced in triple sugar iron agar (TSIA) but can be detected using lead acetate paper.

Antimicrobial Susceptibility Testing for Streptobacillus moniliformis

No standard methods are established.
Penicillin is regarded as the drug of choice.
Aminoglycosides or tetracycline can be used to eliminate the L forms or for patients allergic to penicillin.

Bioterrorism Agents

Category A – Highest priority agents
Certain bacteria are categorized as bioterrorism agents due to their:
- Ease of dissemination or person-to-person transmission.
- High mortality rates.
- Potential for public panic and social disruption.
- Requirement for special public health preparedness actions.
- Bacillus anthracis
- Clostridium botulinum toxin
- Yersinia pestis
- Variola major (smallpox)
- Franciscella tularensis
- Ebola

Category B Bioterrorism Agents

Second highest priority agents
Category B agents are:
- Moderately easy to disseminate.
- Associated with moderate morbidity rates and low mortality rates.
- Require specific enhancements of the CDC’s diagnostic capacity and enhanced disease surveillance.
- Brucella species
- Epsilon toxin of Clostridium perfringens
- Food safety threats: Salmonella, E. coli, Shigella

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SOLO 7