Treatment and Outcome of Carbapenem-Resistant Gram-Negative Bacilli Blood-Stream Infections in a Tertiary Care Hospital.

CONTEXT Infections caused by carbapenem-resistant bacteria constitute a major challenge for current medical practice. OBJECTIVE To describe treatment and outcome of carbapenem-resistant Gram-negative bacilli (GNB) blood-stream infection (BSI) caused by these organisms at a tertiary care hospital in Mumbai. METHODS Carbapenem-resistant isolates from blood cultures were collected from January 2013 to April 2013. Identification and antimicrobial susceptibility testing were performed using Vitek 2 analyzer (Biomerieux Ltd.). Carbapenemase production was detected by modified Hodge's test (MHT). Patient's medical history, treatment and co-morbid conditions were noted. Outcomes of BSIs were evaluated. RESULTS Forty-two isolates of carbapenem-resistant GNB isolated from BSIs were Enterobacteriaceae spp. (19), Acinetobacter baumannii (15), and Pseudomonas aeruginosa (8). Colistin had maximum in vitro activity with 97% against Enterobacteriaceae, 100% against Acinetobacter, and 100% activity against Pseudomonas aeruginosa isolates. Positivity of MHT was 92.9%. Outcome of colistin mono and combination therapy was comparable with 83% and 79%, respectively. Outcome of colistin and carbapenem combination therapy was found to be 100 percent. CONCLUSIONS High incidences of bacteremia by carbapenem-resistant GNB including Enterobacteriaceae is a worrisome trend. Treatment options are compromised and only available option is colistin which has its own limitation. Colistin monotherapy may be non-inferior compared to combination therapy for treating BSIs caused by isolates with minimum inhibitory concentration (MIC) for colistin as ≤0.5 mg/l. Combined use of the colistin and carbapenem may provide good therapeutic options for BSI caused by carbapenem-resistant GNB and warrants further investigations.