Linezolid Resistance against Gram Positive Bacteria Isolated from Blood Stream Infections: A Challenging Threat

The gradual rise of multidrug resistant micro-organisms is a national concern for all health care providers. Linezolid belongs to the oxazolidinone class of antimicrobials. it is a "last resort" used for the management of gram positive bacterial infections. Developing linezolid resistance creates a great challenge for treating bacterial infections. The objective of the current study is to determine the microbial profile and linezolid resistance in gram positive cocci isolated from blood stream infections. 1855 blood samples were analysed for microbial profile and antimicrobial sensitivity testing in our tertiary care centre over a 6 month period. In using Kirby-Bauer's disk diffusion method for antimicrobial susceptibility testing, linezolid resistance was detected according to CLSI guidelines. Out of 1855 blood culture samples, 732 (39.4%) were identified to be culture positive. Amongst culture positive isolates mostly (83.3%) gram negative bacteria were isolated, and 16.7% were Gram positive bacterial isolates. Klebsiella species were the most prevalent among gram negative isolates. The linezolid resistance pattern was coagulase negative staph (CONS) was 25%, staphylococcus was 24% and streptococcus was 20%. This study reveals significant linezolid resistance in gram positive bacteria isolated from blood culture. The emergence of linezolid resistance is a major issue for clinicians treating the infection and it will require prompt monitoring of antibiotic policy and antimicrobial stewardship programs.