Family Enterobacteriaceae Tribe I Escherichiae Tribe II Edwardsielleae
Family : Enterobacteriaceae Tribe I – Escherichiae Tribe II – Edwardsielleae Tribe III- Salmonelleae Tribe IV- Citrobactereae Tribe V – Klebsielleae Tribe VI- Proteeae Tribe VII- Yersinieae Tribe VIII- Erwinieae
Family Tribe • Enterobacteriaceae • Proteus • Morganella Genera • Providencia
� PPA positivity � Motile � Fishy � Part and lactose nonfermenter odor of commensals in human intestine.
� Gram negative � Non capsulated � Pleomorphic � Motile rods
� Possess somatic O � Flagellar H antigens ü H antigen : ability of flagellated strains of Proteus to grow on agar as thin film (from Greek word Hauch – film of breath) ü O antigen : (Ohne Hauche- without film of breath)thin film is not observed when strains have only somatic antigen.
Basis of Weil Felix Reaction � Somatic antigen of certain non motile Proteus strains (X strains)cross react with alkali stable antigen of some Rickettsia species. � To detect heterophile antibodies in sera of patients suffering from Rickettsial infections. � Three OXK non motile Proteus strains : OX 2, OX 19 and
� Widely distributed in nature as saprophytes. � Commensals – moist areas of skin, intestine of humans, animals. � Opportunistic infections � Nosocomial � Struvite pathogens- urinary and septic outbreaks stones in bladder
LAB DIAGNOSIS Specimens collected: Depends on the type of infection. � Suppurative � Urinary lesion- Pus symptoms –urine � Bacteremia & septicemia- Blood
Methods of examination: I) Direct microscopy: � Direct microscopy with Gram stained smear shows gram negative coccobacilli.
� II) � a) Culture: Media used: Blood agar, Mac. Conkey agar , CLED agar b) Cultural Characteristics: ü Blood agar – Swarming is observed with characteristic putrid fishy odor ü Mac. Conkey agarsmooth , colorless colonies
� Gram staining: Smears are examined from the culture plate and reveals Gram negative coccobacilli.
d)Biochemical Reactions : � Indole positive – P. vulgaris / negative – P. mirabilis � MR positive and VP negative � Citrate variable � Urease positive � TSI CATALASE TEST – K/A, gas, H 2 S OXIDASE TEST
III) Antibiotic sensitivity tests done as a guide to treatment. IV)Typing of Proteus – � Bacteriocin typing � Bacteriophage � Dienes typing phenomenon
DIENES PHENOMENON When two strains of Proteus are inoculated on two different areas on culture plate: � If swarming of two strains merge incompletely, remain separated by line of demarcation – two strains are different. � If swarming of two strains merge completely, without any line of demarcation – two strains are identical.
� M. morganii � Commonly found in human and animal feces � Rarely associated with UTI, pneumonia and other nosocomial infections. � Doesnot swarm in culture. � Indole, urease positive but citrate negative � TSI- K/A+gas , No H 2 S
� Associated with nosocomial infections of urinary tract, wounds and burns. � Five species: 1. P. rettgeri 2. P. stuartii 3. P. alcalifaciens 4. P. rustigianii 5. P. heimbache
� P. rettgeri � Motile and P. stuartii-common pathogens but donot swarm
� Characteristic feature of most isolates of Proteus spp. in which a group of cells at the edge of a developing microcolony migrate to an uninoculated area of the medium. � Example of ‘quorum sensing’in which the initiation and regulation of transcription of particular genes occurs only when a critical cell density is reached.
Swarming appears in two patterns : � Continuous swarming � Discontinuous swarming
MECHANISM OF SWARMING: � During an incubation period of about 2– 4 h at 37 C, the bacterial cell, which is in the form of a sparsely flagellate, short (2– 4 µm) bacillus, referred to here as a vegetative cell, cell receives a number of extracellular and intracellular signals--- become multinucleatwed, densely flagellatednonseptate elongated cells (2080 um)in length---swarm cells � Swarm cells migrate to surrounding uninoculated areas resulting in spreading the colonies.
ANTI- SWARMING AGENTS : ü Increased agar concentration to 6% ü Incorporation of alcohol, boric acid 0. 1%, chloral hydrate, sodium azide, sulphonamide, surface active agents, bile salts (interfere with the structure or activity of flagella) ü p-nitrophenylglycerol, which at low concentrations inhibits the formation of swarm cells without affecting the formation or motility of flagella
� Organisms exhibting swarming: ü Proteus mirabilis and P. vulgaris ü Serratia marcescens ü Vibrio parahemolyticus ü Clostridium tetani
� Often multidrug resistant. � Resistant tomany disinfectants � Intrinsic resistance to nitrofurantoin, tetracycline and polymyxin � Resistant to most β lactam drugs � Aminoglycosides and quinoles are effective � In general, P. mirabilis is more susceptible to antibiotics.
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