M.C04C Enterobacter, Proteus, Yersinia

Enterobacter

Gram-negative, facultative anaerobic, non-spore-forming, motile rods belonging to Enterobacteriaceae, commonly found in intestines and environment.

Enterobacter (Name Origin)

Derived from Greek "enteron" (intestine) + "bacter" (rod), meaning intestinal rod.

Enterobacter agglomerans

Soil-borne Enterobacter species; also historically known as Pantoea agglomerans.

Enterobacter aerogenes

Former Enterobacter species now reclassified as Klebsiella aerogenes.

Enterobacter (Motility Mechanism)

Motile via peritrichous flagella.

Enterobacter (Biochemical Traits)

Reduces nitrates to nitrites and ferments glucose producing acid and gas.

Enterobacter (Metabolism)

Can utilize acetate as a carbon source.

Enterobacter (Growth)

Grows on ordinary laboratory media under aerobic or anaerobic conditions.

Enterobacter (Reservoirs)

Soil, sewage, water, and animal excretions including urine, pus, and feces.

Enterobacter (Transmission Routes)

Spread by direct contact or oral acquisition.

Enterobacter (Disease Categories)

Associated mainly with septicemic conditions and enteric infections.

Enterobacter (Virulence Basis)

Pathogenicity largely linked to adhesins and colonizing factors.

MacConkey Agar (Enterobacter Use)

Selective/differential medium used for isolation of Gram-negative enteric bacteria including Enterobacter.

Brilliant Green Agar (Enterobacter Use)

Medium supporting growth of enteric Gram-negative organisms for diagnostic culture.

Enterobacter (Diagnostic Methods)

Identified through bacterial isolation and PCR detection of genes.

Enterobacter (Treatment Options)

Commonly susceptible to tetracyclines and some beta-lactams (lecture context).

Enterobacter (Control Strategy)

Prevention relies heavily on sanitation and carrier elimination.

Proteus

Gram-negative, facultative anaerobic, highly motile rods known for characteristic swarming growth.

Proteus (Name Origin)

Named after the Greek god Proteus due to variability and swarming behavior.

Proteus mirabilis

Most clinically important Proteus species; common cause of UTIs and opportunistic infections.

Proteus vulgaris

Proteus species typically indole-positive and associated with opportunistic infections.

Proteus rettgerii

Less common Proteus species, occasionally isolated from urinary infections.

Proteus (Swarming Motility)

Rapid coordinated surface movement producing concentric wave patterns on agar.

Proteus (Motility Mechanism)

Motility driven by peritrichous flagella.

Proteus (Biochemical Traits)

Produces urease and may produce hydrogen sulfide.

Proteus (Indole Reaction)

Indole production varies by species; Proteus mirabilis usually indole-negative.

Proteus (Glucose Fermentation)

Ferments glucose; other carbohydrate reactions vary.

Proteus (Reservoirs)

Commonly present in feces and urine.

Proteus (Transmission)

Spread primarily by ingestion or contamination from infected material.

Proteus (Major Pathologies)

Urinary tract infections, wound infections, otitis externa, and gastrointestinal disturbances.

Proteus (UTI Mechanism)

Urease hydrolyzes urea → ammonia production → urine alkalinization.

Proteus (Stone Formation Mechanism)

Alkaline urine promotes precipitation of struvite crystals.

Proteus (Virulence Factors)

Urease, proteases, and cytotoxic effects on urinary epithelium.

Proteus (Laboratory Media)

Commonly cultured on MacConkey agar, EMB agar, and Triple Sugar Iron agar.

Triple Sugar Iron Agar

Differential medium detecting sugar fermentation and hydrogen sulfide production.

Proteus (Diagnostic Indicators)

Swarming growth + urease positivity strongly suggest Proteus species.

Proteus (Treatment)

Often treated with cephalosporins, aminoglycosides, or other susceptible antibiotics.

Proteus (Prevention)

Infection control depends on hygiene and sanitation.

Yersinia

Gram-negative, facultative anaerobic coccobacilli often demonstrating bipolar staining.

Yersinia (Name Origin)

Named after Alexandre Yersin, who isolated Yersinia pestis.

Yersinia pestis

Etiologic agent of plague; transmitted primarily by fleas from rodent reservoirs.

Yersinia ruckeri

Pathogen of cold-water fish causing Enteric Red Mouth disease.

Yersinia pseudotuberculosis

Causes septicemic disease and granulomatous lesions in animals.

Yersinia enterocolitica

Enteric pathogen associated with gastrointestinal disease.

Yersinia (Morphology)

Pleomorphic Gram-negative coccobacilli that may appear in chains.

Yersinia (Bipolar Staining)

Produces “safety pin” appearance due to uneven dye uptake.

Yersinia (Temperature-Dependent Motility)

Flagellated and motile at ambient temperatures.

Yersinia (Biochemical Traits)

Ferments glucose and produces urease.

Yersinia (Reservoirs)

Rodents, birds, and soil environments.

Yersinia (Transmission Routes)

Ingestion, flea vectors, airborne spread, predation, scavenging.

Bubonic Plague

Disease marked by lymph node enlargement (buboes), fever, and septicemia.

Enteric Red Mouth Disease

Fish disease characterized by hemorrhhagic lesions around mouth and systemic infection.

Yersinia (Virulence Proteins)

Includes YadA adhesins and plasmid-encoded virulence factors.

YadA Protein

Yersinia adhesin promoting attachment and complement resistance.

Yersinia Outer Membrane Proteins

Virulence-associated proteins interfering with host immune responses.

YpkA (Yersinia Protein Kinase)

Virulence factor inhibiting phagocytosis and oxidative burst.

Yersinia (Immune Evasion)

Capable of resisting complement-mediated killing.

Yersinia (Laboratory Diagnosis)

Identified using serology, hemagglutination tests, PCR, and culture.

Deoxycholate-Citrate Medium

Selective medium used for isolation of certain enteric pathogens including Yersinia.

Yersinia (Specimen Sources)

Lymph nodes, blood, CSF, respiratory samples.

Yersinia (Experimental Diagnosis)

Animal inoculation historically used; rapid mortality in test animals.

Yersinia (Treatment)

Typically treated with aminoglycosides, fluoroquinolones, tetracyclines, chloramphenicol.

Yersinia (Control Measures)

Rodent control, flea elimination, environmental sanitation.

Safety Pin Appearance

Classic microscopic feature strongly associated with Yersinia species.

Peritrichous Flagella

Flagellar arrangement where flagella surround the entire bacterial cell.

Facultative Anaerobe

Organism capable of growth with or without oxygen.

Gram-Negative Cell Wall

Bacterial structure characterized by thin peptidoglycan layer and outer membrane.

Oxidase-Negative

Indicates absence of cytochrome c oxidase enzyme typical of Enterobacteriaceae.

Urease Enzyme

Catalyzes breakdown of urea into ammonia and carbon dioxide.

Hydrogen Sulfide Production

Biochemical reaction detectable on differential media such as TSI agar.