TRENDS OF PATHOGENS CAUSING NOSOCOMIAL BLOODSTREAM INFECTIONS IN IMMUNOCOMPROMISED PATIENTS AND THEIR ANTIBIOTIC SUSCEPTIBILITY
Objective: To determine the frequency of pathogens in nosocomial bloodstream infections and their antimicrobial susceptibility patterns in immunocompromised patients in a tertiary care hospital.
Study design: Descriptive
Place & Duration of Study: Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi from January 2017 to December 2017.
Material & Methods: A total of 97 patients were included in this study. Blood samples were cultured in automated BACTEC 9120 / BacT Alert systems and isolates were identified by standard protocols. Antimicrobial susceptibility testing was done according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Simple descriptive statistics were used to analyze and present the data.
Results: Out of ninety-seven patients with positive blood cultures, 72 (74%) were males. The age range varied from 4 months to 84 years (mean 30 ± 23). Out of these, 64% (n= 62) samples yielded growth of Gram negative organisms, 32.9% (n=32) Gram positive organisms and 3.1% (n=3) Candida species. Predominant isolates among Gram negative organisms were Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa while predominant isolates among Gram positive organisms were Methicillin resistant Staphylococcus aureus, Methicillin resistant coagulase negative Staphylococci & Enterococcus species. Two Candida parapsilosis and one Candida tropicalis were also isolated. Among Gram negative organisms, highest sensitivity was depicted by polymyxin-B followed by amikacin, imipenem and doxycycline, while lowest sensitivity was found among penicillins and third generation cephalosporins. Among Gram positive organisms, highest sensitivity was depicted by linezolid followed by vancomycin, doxycycline, teicoplanin and amikacin, while lowest sensitivity was found among β-lactam drugs. Candida isolates showed highest sensitivity to voriconazole while lowest sensitivity depicted by amphotericin-b and fluconazole.
Conclusion: Trends of BSI causing organisms in immunocompromised patients are shifting from Gram positive to Gram negative organisms. BSI causing microorganisms especially Klebsiella pneumoniae, Acinetobacter baumannii and Methicillin resistant Staphylococci are becoming superbugs and are found highly resistant to most of the antimicrobial drug classes. Polymyxin-B was found sensitive in most Gram negative organisms while linezolid in Gram positive organisms. Most of the Enterococcus isolates were found resistant to vancomycin. Sound hospital infection control practices and policies for restricted use of antimicrobials will help in reducing antimicrobial resistance and life-threatening infections.
Key Words: Blood stream infections, Antibiotic susceptibility, Immunocompromised.