Gram Negative Bacilli PDF

GRAM NEGATIVE BACILLI  Enteric rods  Organisms that infect the gastrointestinal tract of humans and animals  Escherichia coli  Klebsiella pneumoniae  Proteus sp.  Enterobacter  Serratia sp. Facultative  Salmonella sp....

GRAM NEGATIVE BACILLI  Enteric rods  Organisms that infect the gastrointestinal tract of humans and animals  Escherichia coli  Klebsiella pneumoniae  Proteus sp.  Enterobacter  Serratia sp. Facultative  Salmonella sp. anaerobes  Shigella sp.  Vibrio sp.  Campylobacter jejuni  Helicobacter pylori Obligate aerobe  Pseudomonas aeruginosa  Bacteroides sp. Obligate  Fusobacterium sp. anaerobes Non-enteric rods  Organism non commonly found in the GIT.  Haemophilus sp.  Bordetella sp.  Brucella sp.  Pasteurella sp.  Yersinia sp.  Francisella sp. Enterobacteriacea  Large family of enteric organisms containing many pathogens, i.e. Salmonella, Shigella and enteropathogenic E.coli as well as the commensal bowel commensals , i.e. Enterobacter, Providencia, Proteus.  Remember however that any of these species may cause infections at other sites in the body e.g. wound infections (even the commensals) Presumptive identification Lactose fermenter Non-Lactose fermenter  E.coli  Salmonella  Klebsiella sp.  Shigella  Serratia  Proteus  Pseudomonas Lactose Non-Lactose fermenter fermenter Vibrio  Gram negative, cocci-bacilli (comma shaped)  Single terminal flagellum (highly motile)  Cholera  Laboratory diagnosis  Wet preparations Darting movement https://www.youtube.com/watch?v=MqDRPxMovEg  Grows on alkaline media e.g. Thiosulphate citrate bile sucrose (T.C. B.S) agar  Haemophilus  Pleomorphic Gram negative bacilli  Requires X (Heam) and V (co-enzyme I or II / Nicotinamide adenine dinucleotide)  Laboratory diagnosis  Boiled blood agar Have X and V factors readily available  Blood agar X factor is available but not V factor Superimpose with Staphylococcus aureus  Nutrient agar X and V factor not available Place X and V discs  Pseudomonas  Gram negative bacilli, Strict aerobe  Single polar flagellum  Most strains produce pigments  Pyocyanin Blue -green  Pyoverdine Yellow-green  Pyorubin Red-brown  Mostly found in soil and water  Multi-drug resistant pathogen  Frequent cause of nosocomial pathogen  Generally external  Burn wound patience API 20E Preparation of Test organism  Dispense 5ml dH2O in tray  Place strip in tray  Put an loopful of test organism in aliquoted dH20  Vortex  Inoculation of sample  Using the same pipette, fill both tube and cupule of the tests CIT , VP and GEL with the bacterial suspension.  Fill only the tube (and not the cupule) of the other tests.  Create anaerobiosis in the tests ADH, LDC, ODC, H2S and URE by overlaying with mineral oil. Close the incubation box.  Incubate at 36°C ± 2°C for 18-24 hours. Reading and interpretation of results  If 3 or more tests (GLU test + or –) are positive, record all the spontaneous reactions on the result sheet.  TDA Test : add 1 drop of TDA reagent. A reddish brown colour indicates a positive reaction  IND Test : add 1 drop of JAMES reagent. A pink colour developed in the whole cupule indicates a positive reaction  VP Test : add 1 drop each of VP 1 and VP 2 reagents. Wait at least 10 minutes. A pink or red color indicates a positive reaction to be recorded on the result sheet. If a slightly pink color appears after 10 minutes, the reaction should be considered negative. NOTE : The indole production test must be performed last since this reaction releases gaseous products which interfere with the interpretation of other tests on the strip. PRACTICAL COMPLETED