Abstract:
The objective of this paper is to find out the pattern of bacterial pathogens and their
antimicrobial susceptibility from blood culture specimens received from a tertiary care referral
setting. This cross-sectional observational study was carried out at the Department of
Microbiology, Armed Forces Institute of Pathology, from July 2011 through June 2012. Blood
culture specimens were dealt with brain heart infusion broth based manual method and
automated BACTEC system. The specimens yielding positive growth were further analyzed and
antimicrobial susceptibility carried out as per CLSI recommendations. Out of 2921 blood culture
specimens, 465 (16%) yielded growth. Out of these, 245 (53%) isolates were Gram positive, 209
(45%) Gram negatives while 11 (2%) were yeast. Among Gram positive isolates, 208 (85%) were
Staphylococcus spp. and among these 158 (76%) were methicillin resistant. Amongst Gram
negative group, 115 (55%) isolates were members of enterobacteriaceae family and E. coli was
the leading pathogen, while 94 (45%) were non-fermenters (NF). Among these, Acinetobacter
spp. and Pseudomonas aeruginosa were common pathogens. In vitro antimicrobial susceptibility
of staphylococci revealed that 100% isolates were susceptible to vancomycin and linezolid. The
organisms of family enterobacteriaceae revealed better susceptibility to amikacin (68.7%) and
imipenem (64.3%). The NF group showed better in vitro susceptibility to
tazobactam/piperacillin (65%). Gram positive organisms were predominantly causing blood
stream infections. Vancomycin and linezolid in case of Gram positive and amikacin and
tazobactam/piperacillin against Gram negative organisms revealed better in vitro efficacy.
