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Cojo's Step Cards, Bugs > Gram Negative Bacteria > Flashcards

Gram Negative Bacteria Flashcards

1
Q

Lactose Fermenting Bacteria

A

Fast fermenter: Klebsiella, E. coli, Enterobacter

Slow fermenter: Citrobacter, Serratia, Others

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2
Q

Neissera Meningitidis Lab Algorithm, Transmission, Capsule Status, and Treatment

A

Gram negative diplococci that ferments maltose
Transmitted by respiratory and oral secretions
Has a polysaccharide capsule (vaccine available)
Treated with ceftriaxone or penicillin G (?)

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3
Q

Neissera gonorrhoeae Lab Algorithm, Transmission, Capsule Status, and Treatment

A

Gram negative diplococci that does not ferment maltose
Sexually transmitted
No capsule
Treated with ceftriaxone + azithromycin or doxycycline (for chlamydia)

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4
Q

Neissera Presentation

A

Gonorrhoeae: causes gonorrhea, septic arthritis, neonatal conjunctivitis, PID, and Fitz-Hugh-Curtis. Often intracellular

Meningitidis: causes meningococcemia (with petechial rash), meningitis, and Waterhouse-Friederichsen syndrome

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5
Q

Neissera 2 Unique Features

A

Both ferment glucose

Both produce IgA proteases

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6
Q

Haemophilus influenzae Lab Algorithm

A

Gram negative coccobacilli that grows on chocolate agar (requires factors V and X for growth)

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7
Q

Haemophilus influenzae Transmission, Capsule Status, Virulence Factor

A

Aerosol transmission
Type B polysaccharide capsule is most invasive type (vaccine available)
IgA Protease

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8
Q

Haemophilus influenzae Presentation and Treatment

A 
Mucosal infections (nontypeable)
Also epiglottitis (cherry red in children), meningitis, otitis media, and pneumonia

Treat mucosal infections with amoxicillin +/- clavulanate
Treat meningitis with ceftriaxone
Rifampin prophylaxis in close contacts

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9
Q

Legionella pneumophila Lab Algorithm

A

Gram negative rod. Gram stains poorly so use silver stain. Grow on charcoal yeast extract and culture with iron/cysteine
Clinically detected by presence of antigen in urine

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10
Q

Legionella pneumophila Transmission and Treatment

A

Aerosol transmission from environmental water source habitat (air conditioning, hot water tanks, ect.)
No person to person transmission

Treatment: macrolide or quinolone

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11
Q

Legionella pneumonphila Presentation

A

Legionnaries’ disease: severe pneumonia, fever, GI, and CNS symptoms

Pontiac fever: mild flu-like syndrome

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12
Q

Pseudomonas aeruginosa Lab Algorithm

A

Gram negative rod, lactose non-fermenter, oxidase positive

Obligate aerobe

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13
Q

Pseudomonas aeruginosa Presentation

A

Associated with wound and burn infections
Pneumonia, sepsis, external otitis (swimmer’s ear), UTI, drug use and diabetic osteomyelitis, hot tub follicultis

Can also cause ecthyma gangrenosum: rapidly progressive, necrotic cutaneous lesions caused by pseudomonas bacteremia typically seen in immunocompromised patients

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14
Q

Psuedomonas aeruginosa Pigment, Odor, Toxins, and Treatment

A

Blue-green pigment
Grape-like odor
Endotoxin and exotoxin A (inactivates EF-2)
Treatment: amingoglycoside + extended spectrum penicillin

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15
Q

E. coli Lab Algorithm, Virulence Factors, and Treatment

A

Gram negative rod, fast lactose fermenter

Fimbriae (cystitis and pyelonephritis), K capsule (pneumonia and neonatal meningitis), LPS endotoxin (septic shock)

TMP-SMX for UTI and Ceftriaxone for meningitis and sepsis

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16
Q

EIEC (Invasive) Mechanism and Presentation

A

Microbe invades intestinal mucosa and causes necrosis and inflammation

Presentation: dysentery

17
Q

ETEC (Toxigenic) Mechanism and Presentation

A

Produces heat labile and heat stable enterotoxins (no inflammation or invasion)

Presentation: travelers’ diarrhea

18
Q

EPEC (Pathogenic) Mechanism and Presentation

A

Adheres to apical surface and flattens villi, preventing absorption

Presentation: diarrhea usually in children

19
Q

EHEC (Hemorrhagic) Mechanism, Presentation, and Differentiation

A

O157:H7 is the most common serotype. Produces shiga-like toxin that causes HUS (triad of anemia, thrombocytopenia, and acute renal failure)–microthrombi use up the platelets and cause the thrombocytopenia

Presents with dysentery

Does not ferment sorbitol (unlike the other E. coli)

20
Q

Klebsiella Lab Algorithm

A

Gram negative rod, lactose fast fermenter

21
Q

Klebsiella Presentation

A

An intestinal flora that causes lobar pneumonia in alcoholics and diabetics when aspirated

Also cause of UTIs

4 A’s: Aspiration pneumonia, Abscess in lungs and liver, Alcoholics, diAbetics

22
Q

Kelbsiella Capsule Status, Sputum Finding, Treatment

A

Polysaccharide capsule (abundant mucoid colonies)

Red “currant jelly” sputum

Treat with 1st and 2nd gen Cephalosporins

23
Q

Salmonella and Shigella Lab Algorithm

A

Gram negative rod, lactose non-fermenter, oxidase negative

24
Q

Salmonella Information

A

Have flagella, can disseminate hematogenously, animal reservoirs (like turtles), produce H2S, antibiotics prolong fecal excretion, invades intestinal mucosa, can cause blood diarrhea

25
Q

Shigella Information

A

No flagella, cell to cell transmission (no hematogenous spread), humans and primates reservoirs, does not produce H2S, antibiotics shorten duration of fecal excretion, invades mucosa and may cause PMN infiltration, often causes bloody diarrhea

26
Q

Salmonella typhi Presentation

A

Typhoid fever: ROSE spots on the abdomen, fever, headache, and diarrhea

Can remain in GALLBLADDER and cause a carrier state

27
Q

Campylobacter jejuni Lab Algorithm

A

Gram negative, comma shaped, oxidase +, grows in 42 degrees

28
Q

Campylobacter jejuni Presentation

A

Major cause of bloody diarrhea, especially in children
Fecal-oral transmission through poultry, meat, unpasteurized milk
Common antecedent to Guillain Barre and reactive arthritis

29
Q

Vibrio cholerae Lab Algorithm

A

Gram negative, comma shaped, oxidase +, grows in alkaline media

30
Q

Vibrio cholerae Presentation, Epidemiology, and Treatment

A

Rice-water diarrhea via enterotoxin that permanently actives Gs

Endemic to developing countries

Prompt Oral Rehydration

31
Q

Yersinia enterocolitica Lab Algorithm

A

Gram negative rod, lactose non-fermenter, oxidase negative

32
Q

Yersinia enterocolitica Transmission and Presentation

A

Transmitted from pet feces, contaminated milk, or pork

Causes mesenteric adenitis that can mimic Crohn disease or appendicitis

33
Q

Helicobacter pylori Lab Algorithm

A

Gram negative, comma shaped, oxidase +, produces urease

34
Q

Helicobacter pylori Presentation and Treatment

A

Gastritis and peptic ulcers (especially duodenal)

Treatment: PPI + clarithromycin + amoxicillin or metronidzole

35
Q

Pasteurella multocida Lab Algorithm and Presentation

A

Gram negative coccobacilli, oxidase +, catalase +

Cellulitis and osteomyelitis following cat/dog bites

36
Q

Bartonella henselae

A

Gram negative coccobacilli (silver impregnation stains)

Causes cat scratch fever: fever, ocular involvement, hepatosplenomegaly

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