Microbiology: Other Gram Negative Bacteria

Enterobacterales coli characteristics

rods

facultative anaerobes

oxidase negative

glucose and lactose fermentation

Enterobacterales coli virulence factors

Structural antigens:

O - found on polysaccharide of LPS

H - found on flagella

K - polysaccharides of capsules

UPEC clinical significance

most common cause of UTI

UPEC antibiotics

nitrofurantoin

ETEC virulence factors

heat-stable (ST) and heat-labile (LT) toxins

ST increase cAMP

ETEC clinical significance

traveler’s diarrhea

transmitted via fecal-oral route

EPEC virulence factors

pedestal development

EPEC clinical significance

watery diarrhea in infants

non-invasive infection

comes from poor sanitation

EHEC virulence factors

Shiga-like toxins 1 or 2

most common serotype is O157:H7

EHEC clinical significance

hemolytic uremic syndrome (HUS)

can cause thrombocytopenia in children ages 5-10

EHEC antibiotics

not recommended

Salmonella virulence factors

produce H2S

invasion on M cells

intracellular pathogen - evasion of phagocytosis

Salmonella clinical significance

gastroenteritis

enteric or typhoid fever

Typhi and Typhimurium most common serotypes

associated with eggs, poultry, and turtles

chronic carriers - typhi in gallbladder

Salmonella antibiotics

ceftriaxone

ciprofloxacin

Shigella characterisitcs

rods

humans only host

highly infectious

Shigella virulence factors

Shiga toxins

transmitted via fecal-oral route

Shigella clinical significance

shingellosis

invasion/destruction of intestines

bloody diarrhea

HUS with S. dysenteriae

Shigella antibiotics

ceftriaxone

ciprofloxacin

azithromycin

Klebsiella clinical significance

bacteremia

UTI

hospital patients

multi-drug resistant

Klebsiella antibiotics

3rd and 4th generation cephalosporin

Serratia clinical significance

lower respiratory infections

UTI

hospital patients

multi-drug resistant

Campylobacter jejuni characteristics

curved, spiral, or s-shape

darting motility

microaerophilic

Campylobacter jejuni virulence factors

cytotoxin

enterotoxin - related to cholera toxin

Campylobacter jejuni clinical significance

acute enteritis

from wild and domestic animals

transmitted via fecal-oral route

from contaminated meat or water

Campylobacter jejuni antibiotics

azithromycin

Vibrio cholerae virulence factors

AB toxin - cholera toxin that activates Gs protein and elevates cAMP

Vibrio cholerae clinical significance

rice water stool

from consumption of raw or undercooked seafood

from contaminated water

Vibrio cholerae antibiotics

doxycycline

Vibrio vulnificus clinical significance

soft tissue infections

necrotizing fasciitis

from seafood and cuts

Helicobacter pylori characteristics

corkscrew

rapid motility

microaerophilic

Helicobacter pylori virulence factors

urease - neutralize stomach acids

cytotoxin - destruction of mucus-producing cells

Helicobacter pylori clinical significance

acute gastritis

duodenal and gastric ulcers

gastric carcinoma and B-cell lymphoma

Helicobacter pylori antibiotics

metronidazole

tetracycline

Haemophilus influenzae virulence factors

capsule - antiphagocytic

requires factor X and V for growth

Haemophilus influenzae clnical significance

bacterial meningitis in children

neurological sequelae

type b (Hib) - serious invasive disease

Humans only natural host

transmitted via respiratory droplets

Haemophilus influenzae treatment

vaccine

3rd gen cephalosporin

Bordtella pertussis characteristics

coccobacilli

single or pairs

Bordetella pertussis virulence factors

pertussis toxin - AB toxin

catarrhal phase - highly contagious

paroxysmal phase - whooping cough

Bordetella pertussis clinical significance

whooping cough

mild cases in adults

unvaccinated children

Bordetella pertussis treatment

vaccine

azithromycin

Legionella pneumophila characteristics

rods

facultative intracellular parasite

Legionella pneumophila virulence factor

prevents phagolysosomal fusion

Legionella pneumophila clinical significance

Legionnaires disease

pontiac fever

atypical cause of CA-pneumonia

Legionella pneumophila antibiotics

azithromycin

Pseudomonas aeruginosa characteristics

rods

oxidase positive

nonfermentors

facultative anaerobe

Pseudomonas aeruginosa virulence factors

various secretion systems

various toxins

pili

capsule

Pseudomonas aeruginosa clinical significance

green/blue pigment

grape juice and tortilla chip odor

localized infections

systemic infections

biofilms

cystic fibrosis pts high risk

Pseudomonas aeruginosa antibiotics

pipercillin/tazobactam

Moraxella catarrhalis clinical significance

infections: respiratory, middle ear, CNS, joints

Moraxella catarrhalis antibiotics

amoxicillin clavulanate

Acinetobacter baumanii clinical significance

HA - pneumonia

infections - blood and wounds

UTI

Acinetobacter baumanii antibiotics

beta-lactams

carbapenems

Treponema pallidum characteristics

spirochete

endoflagella

required cells for culture

does not contain LPS

Treponema pallidum virulence factors

antigenic variation of surface proteins - immune evasion

hyaluronidase - dissemination

Treponema pallidum clinical significance

syphilis - chancres, rash, and CNS degeneration

congenital syphilis

Treponema antibiotics

penicillin IV

Borrelia burgdorferi clinical significance

lyme disease - rash that progresses to chronic arthritis and CNS disease

Borrelia burgdorferi characteristics

spirochete

endoflagella

require cells for culture

no LPS

Borrelia burgdorferi antibiotics

doxycycline