Widely recognized as the common cause of UTIs
Escherichia coli
Selective and differential agar used for isolation of (non-fastidious) gram negative bacilli on basis of lactose fermentation
MacConkey agar
Heat stable antigen in cell wall, part of LPS
O antigen (somatic antigen)
Can form a neon green sheen on EMB agar
E. coli
Indole positive, TSIA A/A with gas production
Escherichia coli
Has a large polysaccharide capsule making colonies very snotty
Klebsiella pneumoniae
Agar that tests primarily for carbohydrate fermentation & hydrogen sulfide production, but also gas production
Triple Sugar Iron agar
Contain chemicals that allow bacterial cells to bind to host cell surfaces
Fimbriae or pili
Best known for hospital-acquired pneumonia that may cause "red currant jelly sputum"
Klebsiella pneumoniae
Lactose positive, TSIA A/A with gas production, motile and indole negative
Enterobacter
Half of isolates produce characteristic brick red colonies on BAP
Serratia sp.
Agar used to differentiate G- enterics on basis of H2S production, indole formation, and motility
Sulfide Indole Motility agar
Produces two toxins that release into the small intestines and causes "Traveler's Diarrhea"
Enterotoxigenic E.coli (ETEC)
Loves damp environments and frequently grows in the shower or bathroom sinks
Serratia marcescens
Lactose negative, TSIA K/A, ONPG positive, DNase positive
Serratia
Distinct burnt brownies smell and phenylalanine deaminase positive
Proteus sp.
Hektoen Enteric agar (HE) and Xylose Lysine Deoxycholate agar (XLD)
Toxin produced by Enterohemorrhagic E.coli (EHEC)
Shiga toxin (aka STEC)
Frequently causes catheter-associated UTIs in hospital patients
Providencia
Can be lactose positive or negative, TSIA can be A/A or K/A, H2S negative or positive, citrate positive, ONPG positive
Citrobacter
Associated conditions of this genus include watery/chronic diarrhea in the tropics and subtropics
Plesiomonas sp.
A versatile agar that differentiates E.coli and Enterobacter aerogenes, IDs Candida albicans, and IDs coagulase positive Staph.
Eosin Methylene Blue agar
Creates "pebbles in pond" or "swarming" look on BAP due to peritrichous flagella
Proteus
Commonly found in aquatic animals, can cause deep abscesses or wound infections after water exposure
Edwardsiella
Lactose negative, TSIA K/A, H2S positive, rapid urease positive, phenylalanine deaminase positive
Proteus