Gamma Proteobacteria:
ENTERICS
Gram negative rods
Facultative anaerobes
Oxidase (-)
Catalase positive
Ferment glucose
Reduce nitrates to nitrites
Virulence: Fimbria for attachment
Sex Pili for tranmsision of resistance (AB)
Bacteriocins ā proteins that cause the lysis of related species
Enterobacter
E. aerogenes
E. cloacae
Nosocomial infection
Reservoir: colon, soil, water, sewage
Diseases: UTI, pneumonia
Virulence factor: AB resistance
Endotoxin
TX: AB [broad spectrum penicillin]
Klebsiella
Klebsiella pneumonia
Nonmotile
Nosocomial infections
Rare, but severe pulmonary infection
Reservoir: Human URT, soil, water
Clinical signs: dark brown to cherry red jelly like sputum
Lung abscesses
Empyema
Most common in diabetics, alcoholics, chronic respiratory
Virulence factor: polysaccharide capsule
DX: culture organism
TX: AB [cephalosporins and aminoglycocides]
Serratia
Serratia marcescens
Nosocomial : catheters, Saline irrigation solutions
Reservoir: colon, soil, water
Diseases: UTI, pneumonia
Virulence factor: AB resistance
Endotoxin
TX: AB [broad spectrum penicillin]
Proteus
P. mirabilis
P. vulgaris
Highly motile. Peritrichous flagella
Habitat: colon, soil, water
Disease: UTI, wound sepsis (catheter infections)
Virulence: Endotoxin
Urease +
Morganella
M. morganii
Habitat: feces, soil, water
Clinical disease: found in superficial
wounds where normal flora is absent and cause Infections of ear, sinuses, urinary tract
Providencia
P. rettgeri
P. alcalifaciens
P. stuartii
Same as above regarding habitat and clinical disease
Pasteurellales
Nonmotile, gram neg rods
Haemophilus [see other notes]
Pasteurella
Pasteurella multocida
Pneumonia and sepsis in animals
Zoonotic Dz: transmitted by animal bite [dog, cat]
Humans: abscess ā arthritis
Epsilon proteobacteria
Slender gram neg rods
Helical or vibroid
Motile
Microaerophilic
Campylobacter
Transmission: Indirectā contaminated or undercooked food; contaminated water
C. jejuni
Clinical signs: Enteritis, ulcerative colitisāwatery, bloody diarrhea
Can progress to endocarditis ā septic arthritisā meningitis
DX: growth on selective media
TX: AB [erythromycin, ciprofloxacin]
C. fetus
Diseases: bacteremia in susceptible patients [DM, cirrhosis]
Diarrhea
C. coli
Diseases: diarrhea
Helicobacter pylori
Diseases: peptic ulcers
Gastric carcinoma
Virulence factor: Urease +
TX: AB [metronidizole]
OTHER ORGANISMS
Bacteroidetes
Bacteroides fragilis
Gram neg rod
Anaerobic
nonmotile
Reservoir: Human intestine
Diseases: PID, Peritonitis, Abscesses
TX: Metronidizole
Francisella tularensis
Gram negative pleomorphic coccobacillus
Non motile
Non sporeformer
Reservoir: Rabbits and Rodents that carry Type A
Water and aquatic mammals that carry Type B
Transmission: Ingestion, inoculation, inhalation, contamination, biting vector such as a tick or biting horse fly
Incubation: 5-8 days
Clinical sign: Headache/chills/ fever ā N/Vāpustular papule that ulcerates to cause focal necrosis of infected organs -->Finger, eye, Lymphatic system, liver, kidney, lung
Virulence factors: capsule
Endotoxin (LPS)
TX: AB [streptomycin]
Streptobacillus
S. moniliformis
Causative agent of Streptobacillary rat bite fever
Reservoir: oropharynx of rats
Transmission: Direct (bite), Indirect (contamination of milk)
Clinical Signs: Flu like signsā rashā polyarthralgiaā endocarditis
DX: Id organism on culture of blood or joint fluid
TX: AB [penicillin or erythromycin]
Plesiomonas shigelloides
Gram neg rod
Facultative anaerobe
Reservoir: Gut of fish
Transmission: Eating raw fish, contaminated food or water
Clinical Disease: Diarrhea
TX: AB
Aeromonas hydrophilia
Gram neg rod
Reservoir: soil and water
Transmission: contaminated food
Clinical Disease: diarrhea
Virulence factor: enterotoxin
TX: AB
Alcaligenaceae
Alcaligenes denitrificans
Alcaligenes faecalis
Bordetella pertusis
Gram neg bacillus
Aerobic
Nonmotile
Transmission: Respiratory droplet
Clinical Disease: Pertussis [Whooping cough]
Malaise/ fever ā mucus accumulatesā paroxysmal coughing for weeks to months
Virulence factor: Pili/Fimbria that attach to cili of URT cells
DX: organism on culture sample
TX: AB [penicillin, erythromycin]
Prevention: Vaccination [DTaP] p = pertussis