Medically Relevant Bacteria - Gram Negative Curved and Cooccobacilli-LM

Question 1

This is a gram neg, curved rod bacteria with a single polar flagellum. It is a non lactose fermenter but ferments glucose. What is it from this discription and the pictures

Answer 1

Vibrio Cholerae

Question 2

How is vibrio cholerae transmitted

Answer 2

• Usually a disease of poor sanitation (water with human fecal contamination)
• Large dose is required to produced disease due to acid in stomach killing organisms

Question 3

V cholerae is a non invasive enterotoxogenic bacterium that produces a potent enterotoxin choleragen? how does it work?

Answer 3

• A domain controls its biologic activity
• A1 peptide enzymatically transfers ADP-ribose from NAD to a GTP regulatory protein which leads to activation of adenylate cyclase and the overproduction of cyclic AMP
• B domain binds the toxin to cellular receptors (GM1 receptor)

Question 4

How would you Dx cholerae?

Rx?

Answer 4

• Dx- voluminous “rice water stool” presumptive for cholera
• Gram stain stool to see organism or
• Isolation using V. Cholera selective thiosulfate-citrate-bile salts-sucrose (TCBS) agar
• Rx – fluid and electrolyte replacement, doxycycline can shorten disease course

Question 5

A gram neg, curved rod, is a non lactose fermenter, motile,
•Ingestion of contaminated water, milk or undercooked foods (raw clams) causes.

What is it?

Answer 5

Campylobacter jejuni

Question 6

How does campylobacter jejuni infection progress?

Answer 6

• Enteroinvasive and after 2-4 day incubation get acute enteritis (fever, loose bloody diarrhea, nausea and abdominal pain)
• Generally self-limiting but may last a week
• Relatively small inoculum is required to cause illness

Question 7

For C. jejuni, how would you…

DX

RX

?

Answer 7

• Dx - Gram stain may reveal curved (“seagull” or “comma”) shaped organisms, culture at 5% O2, 10% CO2, 85% N2 at 42°
• Rx – early erythromycin treatment may shorten disease course

Question 8

This picture is showing a gram neg,bacteria that is a non lactose fermenter.
•Lives in the mucus layer above the gastric epithelium and produce urease (buffered from acid)
What in the picture is characteristic of its name?

Answer 8

Helical shape

Helicobacte pylori

Question 9

H pylori transmits feco-oral or oral-oral; what other conditions is it associated with?

How does it cause these?

Answer 9

• Associated with chronic gastritis, gastric and duodenal ulcers, gastric adenocarcinoma and gastric MALT lymphoma
• Down regulation of somatostatin-producing D cells leads to elevated gastrin levels and enhanced acid secretion
• Chronic superficial gastritis → atrophic gastritis → adenocarcinoma

Question 10

What would you use to Dx H pylori? think about the fact is produces urease.

Rx.

Answer 10

Breath urea test was highlighted but

• Stool antigen test, urease test on biopsy, breath urea test, IgG serology, visualized microscopically, cultured on chocolate agar in a microaerophilic environment
• Rx – PPI, clarithromycin, and amoxicillin, or metronidazole (clarithromycin-based triple therapy) or a PPI or H2RA, bismuth, metronidazole, and tetracycline (bismuth quadruple therapy)

Question 11

These are obligate anaerobes so they like to live in abcesses, most encapsulated, non lactose fermenter, gram neg bacilli or cocco bacilli? Does the picture help? What are they?

Answer 11

Bacteroids and prevotella

Question 12

These are all opportunistic with immunosuppression but B fragilis has what virulence factor?

Dx?

Rx?

Answer 12

Anti-phagocytic capsule

• Dx - Gram stain and ANAEROBIC culture
• Rx frequently resistant to many antibiotics and local antibiotic susceptibility patterns are needed as well as antibiotic sensitivity of the patient’s cultured organism
• Debride necrotic tissue, drain pus

Question 13

Where are Prevotella sp. found?

What can they cause?

Answer 13

Prevotella sp. are similar to, and previously classified as, bacteroides

• Part of the normal oral and vaginal flora
• Can cause obstetric and gynecologic infections, aspiration pneumonia, chronic otitis media and sinusitis, and abscesses in lung, oral cavity, brain abscesses, and human bite wounds

Question 14

This is a picture of a gram neg coccobacilus, aerobic, non-motile, aquatic. First ID the organism then tell me what is significant about what it produces?

Answer 14

Acinetobacte baumannii

Produces B-lactamase

Question 15

How does acinetobacter baumannii present?

Dx

Rx

Answer 15

• Nosocomial infections or immunocompromised patients
• Commonly colonizes irrigating and INTRAVENOUS solutions (so can go almost anywhere in body)
• Respiratory tract, CSF, peritoneal fluid, urinary tract infections
• Dx – culture
• Rx – amikacin, minocycline (intrinsically resistant to cephalosporins, macrolides, and penicillins and developing resistance to carbapenems)

Question 16

Haemophilus is a gram neg coccobacilli whose capsule is a major virulence factor. It is spread by direct contact (day care centers)

What are the types of haemophilus that we learned about?

What type of people must be vaccinated?

Answer 16

Influenzae

Influenzae Type B

Ducreyi

Parainfluenzae

aegypticus

ASPLENIC

Question 17

How does H influenzae present?

What is special about type B?

Answer 17

•Pneumonia, acute epiglottitis, bacteremia, meningitis, septic arthritis, cellulitis, otitis media, purulent pericarditis, endocarditis, arthritis and osteomyelitis

• H. influenzae type b - most common cause of bacterial meningitis in children 6 months-2 years
• Unencapsulated strains produce ear, sinus and respiratory infections (usually chronic smokers, alcoholics or elderly)

Question 18

What is this

Answer 18

Chancre caused by H ducreyi.

Will also cause this ( painful, unilateral); its called bubbos by the way.

Question 19

H parainfluenzae,

H aegypticus presentation

Answer 19

pneumonia endocarditis;

conjunctivitis

Question 20

H. Parainfluenza Dx

Rx

Prevention

Answer 20

• Dx -Gram stain of CSF, capsular antigen detections, culture is fastidious (10% CO2 required) and organisms require factors X (hemin) and/or V (NAD) in media (present in chocolate agar), PCR
• Rx –IV or parenteral third generation cephalosporin
• Prevention – 3 doses of one of the following: MONOVALENT Hib VACCINE, quadrivalent Hib vaccine (Hib + DTP), pentavalent Hib vaccine (Hib + DTP + hepatitis B)

Question 21

Gram neg coccobacilli that is encapsulated and a strict aerobe? The main one is also called whooping cough, what is it.

Answer 21

Bordetella pertussis- spread by direct contact

Question 22

What are the exotoxins that Bordetella produces?

Answer 22

• Filamentous hemagglutinin: involved in attachment to host cells
• Pertussis Toxin: adp-ribosyl-transferase that interferes with G-protein signals from cell surface receptors (A subunit) and involved attachment to respiratory epithelia and mφs (B-subunit)
• Invasive adenylate cyclase toxin: increases cAMP, inhibiting immune effector cell functions
• Tracheal cytotoxin: causes ciliostasis and loss of ciliated epithelial cells
• Lethal (dermonecrotic) toxin: heat stable and causes tissue destruction

Question 23

Whooping cough has stages of the disease can you describe them

Catarrhal

Paroxysmal

Convalescent

Answer 23

• Highly contagious laryngotracheobronchitis usually seen in infants
• 7-14 day asymptomatic incubation period
• Catarrhal stage - fever, rhinorrhea and a highly infectious cough
• Paroxysmal phase - spasmodic “whooping” cough that may last 6 weeks with posttussive vomiting and lymphocytosis accompanied by minimal granulocytosis
• Convalescent phase - secondary complications may occur (encephalopathy, seizures and pneumonia)

Question 24

Bordetella pretussis Dx

Rx

Prevention

Answer 24

• Dx – clinical symptoms, PCR, grown on Bordet-Gengou agar media, and serologic testing
• Rx – erythromycin can shorten disease course
• Prevention – DTaP vaccine x 5 followed by Tdap( this is important) in adulthood (acellular pertussis not as protective as pre-1997 whole cell preparations DTwP)

Question 25

Yersinia is a gram neg coccobacilli, what make is different from all the others?

Answer 25

Bipolar stain

Non lactose fermenter

Glucose fermenter

Question 26

Y. enterocolitica and Y. pseudotuberculosis cause disease via ingestion of contaminated water or food, what symptoms would you see and how would you treat?

Answer 26

• Produces enterotoxin similar to E. coli heat stable toxin
• Enteroinvasive self-limited ileitis, gastroenteritis characterized by fever, abdominal pain that may mimic appendicitis, diarrhea, and mesenteric lymphadenitis
• Dx - culture
• Rx - ampicillin or tetracycline

Question 27

What kind of Yersinia is called the bubonic plague or black death?

How is it transmitted?

What virulence factors does it have?

Answer 27

• Bubonic plague (black death) maintained among rodent populations (ground squirrels, prairie dogs, great gerbils/black rats for exam questions) transmitted by infected fleas (regurgitate biofilm from gut)
• Facultative intracellular pathogen
• Two antiphagocytic components
• F1 antigen and the V & W antigens (both required for virulence) only produced at 37°, the bacteria are capable of surviving and multiplying within monocyte, and upon emerging from the monocytic host they possess these antigens
• Yops proteins inhibit inflammatory cytokine production

Question 28

Yersinia pestis causes, what are the presentations

Bubonic plague

Septicemic plague

Pneumonic plague

Answer 28

• Bubonic plague occurs within a week of being bitten by an infected flea, bacterial proliferation produces the “bubo” (swollen, painful lymph node), bacteremia follows, causing death in about 75% in a few days
• Septicemic plague – bacteremia and bacterial endotoxins cause disseminated intravascular coagulation (DIC), with bleeding into the skin and other organs; usually fatal
• Pneumonic plague occurs under crowded conditions when contaminated respiratory droplets expelled by infected persons are directly inhaled by another person; shorter incubation period and greater mortality (90% in 1 day) than bubonic plague

Question 29

Y pestis

Dx

Rx

Prevention

Answer 29

• Dx - Examination of sputum or a lymph node biopsy (Gram-negative, bipolar coccobacilli), culture, immunofluorescence or PCR; P-3 level containment is required
• Rx - Treatment must be rapid and aggressive w/ streptomycin and gentamycin
• Prevention - Vector control and inactivated Y. pestis vaccine for lab personnel handling organism (IM x 3)

Question 30

Gram neg, pleomorphic coccobacillus, non motile, aerobic, the big clue is that it is intracellular and proliferates in macrophages, what is it?

Answer 30

Francisella tularensis

Question 31

Primary vectors are ticks and deer flies but Type A and B also have different vectors, what are they?

Answer 31

• F. tularensis tularensis (Type A) found in lagomorphs (rabbits, hares and pikas) in North America
• F. tularensis palaearctica (Type B) in aquatic rodents (beavers, muskrats) in North America and hares and small rodents in northern Eurasia

Question 32

What are some of the ways to get Tularemia?

Dx

Rx

Answer 32

• Ulceroglandular (most common, via insect bite or handling rabbits ,skin lesion + buboes)
• Glandular
• Oropharyngeal (follows ingestion via food or water)
• Pneumonic (hematogenous or inhalational (dressing rabbit) fever, sore throat, pneumonia and pleuritis)
• Oculoglandular (infection via eyes)
• Typhoidal (via GI tract)
• Dx - culture on buffered charcoal and yeast extract (requires cysteine), PCR, antibodies in the serum (false cross reactivity with Brucella)
• Rx - streptomycin

Question 33

This is similar to F tularenis and also proliferates in macrophages,
•Generally zoonosis via occupational exposure to infected animal
•Outbreaks via ingestion of unpasteurized milk products and undercooked meat
There are many different types named for their vector can you think of any?

Answer 33

• Worldwide distribution but mostly eradicated in the United States
• Brucella abortus - cows
• B. melitensis – goat, sheep, camels
• Unpasteurized milk caused Malta/undulant/Mediterranean fever
• B. suis - pigs
• B. canus - dogs
• B. ovis (sheep, goats)
• B. neotomae (wood rats), B. pinnipediae (pinnipeds - seals, sea lions, walruses), B. ceti (cetaceans - dolphins, porpoises, whales), B. microti (common vole)

Question 34

How does Brucellosis present

Dx

Rx

Answer 34

•The organisms may produce a localized abscess, which is followed by bacteremia
•Undulant fever - Flu-like symptoms with limb and back pain, intermittent fever, malaise
•Can cause subacute or chronic disease
•B. melitensis and B. suis are more transmissible to humans
•

Dx -Cultures incubated 3-4 weeks in a 5-10% CO2-enriched environment or Brucella microagglutination test (BMAT)

Rx - Doxycycline (or ciprofloxin) plus rifampin (or streptomycin) MUST treat right away.

Question 35

SD Schaffner is bit by an animal, maybe a cat and his hand looks like this, what is it?

Answer 35

Pasteurella multicida

Question 36

Pasteurella multicida comes from numerous animals is a gram neg coccobacilli, non motile, facultative anaerobe.

How does it present?

Dx

Rx

Answer 36

•Cellulitis with bloody drainage from wound, may progress to joint infections, osteomyelitis, meningitis and endocarditis
•Usual infection is from domestic pet bites
•
•Dx – Clinical presentation and culture
•Rx - amoxicillin-clavulanate preferred since bite infections are polymicrobial