PATHOGENS CAUSING BLOOD STREAM INFECTIONS

IN CARDIAC PATIENTS & THEIR SUSCEPTIBILITY PATTERN FROM A TERTIARY CARE HOSPITAL

Abstract

Blood stream infections (BSI) remain a major cause of debility and death around
the world. BSI accounts for 10-20% of all Nosocomial infections. Empirical antimicrobials are
based on the susceptibility pattern of the pathogens isolated in a specific institute from time
to time. We have conducted this study only on cardiac Patients over two & half years of study
duration. Study design: Cross sectional study. Settings: Microbiology Department, Allama Iqbal
Medical College/Jinnah Hospital, Lahore. Study Period: January 2013 to July 2015. Materials
& Methods: A total of 5411 blood culture specimens were collected from cardiac patients
including patients admitted to cardiology ward, coronary care unit (CCU), pre-operative and
post-operative cardiac surgery patients. The bottles containing BHI broth were incubated and
were subcultured after 24 hours, 72 hours, 120 hours, and 168 hours on blood and MacConkey
agars. Isolates were further identified with the help of Gram staining, biochemical reactions
and rapid tests like catalase, oxidase, coagulase, Analytical Profile Index (API) 20E and API
20NE. Antimicrobial susceptibility of the isolate was carried out on Mueller-Hinton agar by
Modified Kirby Bauer disc diffusion technique according to the isolate as per recommendations
of Clinical and Laboratory Standards Institute (CLSI) guidelines 2013. Results: Out of total 5411
patients, 3958(73.14%) were male, 1453(26.85%) were females. Out of total 5411 Specimens,
only 486 (8.98%) were positive for bacterial growth. Out of total 486 positive blood cultures,
261 (53.71%) were Gram positive isolates and 225 (46.29%) were Gram negative isolates.
Out 486 positive blood cultures, 96 (19.75%) were from cardiology ward, 67 (13.78%) were
from CCU, 113 (23.25%) were from pre operative cardiac surgery ward, 210 (43.20%) were
from post operative cardiac surgery ward. Among Gram positives, Staphylococcus Species
were most common organism isolated from 246 (50.61%) blood culture specimens. Among
Gram negatives, Pseudomonas aeruginosa and E.coli were predominant organisms, isolated
from 81(16.66%) and 72(14.81%) blood culture specimens respectively. Conclusion: Gram
Positive isolates were more common as compared to Gram negative isolates. Vancomycin and
Linezolid were the most effective drugs among Gram positive isolates. Piperacillin-Tazobactam
was most potent antimicrobial against Pseudomonas aeruginosa. For coli forms Tigecycline
was most effective drug.