Enteric Gram-Negatives Flashcards
UTI and urosepsis in elderly nursing home resident
UPEC (E. coli leading cause of UTI)
Enteric infection with hemorrhagic colitis in child
EHEC O157:H7 (E. coli 4th leading cause of enteric infection in US)
Neonatal sepsis & meningitis
NMEC, K1 E. coli (#2 cause)
Normal commensal bowel microbiota
All E. coli
Laboratory workhorse
K12 E. coli
G- Membrane
Inner membrane
Thin peptidoglycan membrane (periplasm w/LPS)
O-antigen
Oligosacc side-chains (endotoxin)
Traveller’s diarrhea
ETEC
childhood diarrhea in underdeveloped places
EPEC
2 ways of getting a UTI
Descending via hematogenous spread
Ascending via periurethral region (colon microbiota)
Ascending aka retrograde most common: Gut - urethra - bladder (bacteriuria) - ureter - kidney (pyelonephritis)
Leading cause of UTI
E. coli
Type 1 fimbrae
PAP
Siderophores
Produces urease
Proteus
Can lead to stone production and obstruction
Diarrhea
Frequent stools
Painless, no fever
Infectious and non
Increased secretion/decreased absorption in SI or LI
Dysentery
Pus and blood in stool
Painful (cramps, tenesmus)
Fever
Invasion or cytotoxin destruction of LI
Enteric fever
systemic infection starting in GI tract
e.g. typhoid
Gastroenteritis characterisitcs
Catch-all for syndromes
NVD
Toxins or superficial inflammation
Infectious and non-
High acid tolerance organism (2)
Shigella
EHEC
Top 4 bacterial causes of enteric infections
Campylobacter (1/2)
Salmonella
Shigella
E. coli
Traveller’s diarrhea
Similar to vibrio cholera (toxin)
ETEC
Infantile diarrhea
Similar: non-typhoid Salmonella
EPEC
Hemorrhagic colitis, HUS
O157:H7
Cow intestines
Similar: Shigella (Verotoxin “shiga-like”)
EHEC
O, H, K antigens
O: part of LPS in the outer membrane
H: flagella (motility)
K: capsule
Sepsis bugs (PEEK)
Proteus
Escherichia
Enterobacter
Klebsiella
Pneumonia bugs (SEEK)
Serratia
Enterobacter
Escherichia
Klebsiella
Meningitidis bug
Escherichia
UTI bugs (PEP)
Proteus
Escherichia
Providencia
Gastroenteritis bugs (YESS)
Yersinia
Escherichia
Salmonella
Shigella
Campylobacter
Intraabdominal infection
Escherichia
Enterobacter physiology (3)
Facultative anaerobes
Ferment glucose
Oxidase-negative
Tracheobronchitis bug
Bordetella pertussis
URI/OM/meningitis/sepsis bug
Haemophilus
Gastritis/ulcers/gastric cancer bug
Helicobacter
URI/OM bug
Moraxella
Genital infection/STI
Nasopharyngeal colonization/meningitis/sepsis
Neisseria gonorrhea
Neisseria meningitidis
Lung/skin/eye/burn/wound/blood
Pseudomonas
Gastroenteritis/skin lesion bug
Vibrio
4 leading bacterial enteric pathogens in the US
Campy
Salmon
Shiggy
Escher
Type 1 pili attach to what?
Mannose molecules
P pili or “PAP” attach to what?
Host receptor? P1 blood phenotype assoc w/?
P for “pyelonephritis” attach to gal-gal
P blood group antigen on renal pelvis cells
P1 phenotype have predisp to recurrent upper-UTI
MR of uropathogenic ecoli?
Biofilms
Capsules do 3, capsular agents e.g. (NESH)
Size, charge, concealment Neisseria Ecoli Strep pneumo H. flu type b
Siderophores
secreted iron-chelating compounds that compete w/host iron-binding compounds
How does Neisseriae scavenge iron?
surface proteins bind host iron-containing transferrin and lactoferrin
4 cytotoxins to know
Shiga toxin (shigella) Verotoxin (EHEC) Vacuolating toxin (H. pylori) Exotoxin A (pseudomonas)
Hydrolytic enzyme bugs (2)
Pseudomonas (lots)
NeisseriAe, hAemophilus –> IgA protease
Acid tolerance:
Shigella, EHEC
Vibrio
Salmonella
Highly resistant (1-100) Highly sensitive (+10^8) Intermediate (10^6)
UTI RF’s
catheter
abx
immunocomp
environment –> selective pressure
Most common source of bacteremia in the elderly?
urinary tract
How does E coli get in?
Principally via mouth
Important molecule for ascending UTI?
Adhesins –> stick to uroepithelium
Targets for vaccines
providencia
Nosocomial UTI in catheterized pts
From animals/environment
normal intestinal microbiota
urease producer –> alkalization of urine
–> salt precipitation –> struvite stones
adhesive pili
proteus mirabilis
K1 encapsulated NMEC
2nd in bacterial neonatal meningitis (GBS #1)
No opsonization –> sialic acid abundant in mammals, poorly immunogenic (mom doesn’t make antiB’s)
Do GNR’s cause CAP in healthy individuals?
No. Elderly, alcoholics, IV drug users, lung disease
Nosocomial pneumonial common in hospitalized pts
4 Klebsiella spp that cause pneumonia (poor)
Pneumoniae
Oxytoca
Ozaenae
Rhinoscleromatis