Metallo- β - lactamase producing nonfermentative gram-negative bacteria: an increasing clinical threat among hospitalized patients

OBJECTIVE@#To detect and evaluate the various methods for metallo- β -lactamases (MBL) production in Pseudomonas aeruginosa (P. aeruginosa) and Acinetobacter species.@*METHODS@#A total of 109 P. aeruginosa and 85 Acinetobacter species were screened for imipenem resistance by Kirby-Bauer disc diffusion methods. Detection of MBL production was done by imipenem-EDTA combined disc test, double disc synergy test (DDST) and imipenem-EDTA MBL E test.@*RESULTS@#A total of 63 (57.8%) strains of P. aeruginosa and 46 (54.1%) strains of Acinetobacter spp. were found to be resistant to imipenem. Of the 63 imipenem resistant P. aeruginosa tested for MBL production, 44 (69.8%) were found to be positive and among 46 imipenem resistant Acinetobacter, 19 (41.3%) were shown to be the MBL producers.@*CONCLUSIONS@#Imipenem-EDTA combined disc test and MBL E test are equally effective for MBL detection in both P. aeruginosa and Acinetobacter spp., but given the cost-constraints, combined disc can be used as a convenient screening method in the clinical microbiology laboratory.

Salmonella-salmonellosis-rare presentations of a common pathogen

Salmonella are most commonly associated with gastroenteritis and enteric fever in humans. Occasionally, dissemination of bacilli throughout the body results in establishment of localized foci of persistent infection especially in patients with debilitating diseases and immunosuppressive states. Infection at various aberrant sites due to Salmonella has been reported relatively seldom. It has perfected the art of intracellular survival in niches from where they can cause myriad of effects. Six cases with Salmonella infection at unusual sites without any preexisting or underlying disease diagnosed over a period of two years are presented here. Salmonella etiology was not suspected in these patients and the diagnosis was made microbiologically only after culture isolation.