Enterobacter, hafnia & serratia (1)

gram negative bacilli

1. Enterobacter , Hafnia & Serratia By Ekta Gupta

2. Enterobacter Enterobacter is gram negative bacillus that belongs to the Enterobacteriaceae family. S imilar to Klebsiel l a in most biochemical reactions (VP positive and lactose fermenter) bur differs from the latter in being motile and ornithine decarboxylase positive.

3. Cont …. • E. aerogenes and E. cloacae are the most commonly isolated species from the clinical specimens. They are also widely distributed in water, sewage, soil and feces of healthy persons. • They are opportunistic pathogens, implicated in infected wounds and urinary and respiratory tract infections and occasionally septicemia and meningitis.

4. Cont … • E. asburiae differs from other Enterobacter in being non-motile and VP negative. It has been isolated from blood , wound and feces . • E. sakazakii strains are biochemically similar to E . cloacae except that they produce yellow pigment, do not ferment sorbitol and may give PPA test positive. They have been isolated from cases of neonatal meningitis and septicemia ,

5. HAFNIA H . a lvei , the only species under genus Hafnia , which is rarely isolated from wounds, abscess, sputum, urine and blood. • It is lactose non-fermenter and positive for lysine and ornithine decarboxylase. • Like Serratia , the biochemical reactions are best reliable when rested at 30'C.

6. SERRATIA The characteristic property of Serratia is production of a red non-diffusible pigment called prodigiosin , which is formed optimally at 30'C. • S. marcescens is the medically most important species. Human infection with other species is rare . Effect of Ph , Temp & Incubation time on prodigiosin

7. Cont … It is a saprophyte found in water, soil and food. It may grow in sputum after collection and makes the sputum red (due 10 pigment production). This condition is known as ' pseudohemoptysis '. S marcescens is being increasingly reported in various nosocomial infections , such as meningitis , endocarditis, septicemia , urinary, respiratory and wound infections.

8. Cont.. The hospital strain are often non-pigmented and multiple drug resistant (produce AmpC Beta-lactamases ) • The biochemical properties of S. marcescens include: 1-Production of lipase , gelatinase and DNase • Resistant to colistin and cephalothin .

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