Carbapenem-Resistant Gram Negative Bacilli Are Predominantly Multidrug or Pan-Drug Resistant

Carbapenems, although originally introduced against multidrug-resistant (MDR) Gram negative bacilli (GNB), are now advocated for initial empiric use resulting in increasing carbapenem-resistant (CR) GNB. In this study, we analyzed the frequencies of CR-GNB and compared their resistance patterns against other antibiotics. Overall, 42% (1,014/2,420) of CR-GNB were isolated (range: 29-59%), with similar frequencies among hospitalized and community-acquired infections. However, the CR frequencies in Acinetobacter baumannii were significantly higher in the hospitalized patients (>50%). In addition, the CR-GNB isolates showed significantly higher resistance to the other antibiotics-fluoroquinolones, aminoglycosides, sulfonamides, and ureidopenicillins compared to carbapenem-sensitive isolates, thereby limiting further treatment options. Majority of CR-GNB isolates were extended spectrum β-lactamase producers (38-72%) and MDR (19-61%). Pan-drug resistant (PDR) frequencies among these MDR isolates ranged from 21% (Proteus spp.) to 100% (A. baumannii). Overall, CR-GNB are predominantly MDR or PDR and so warrant continuous antibiotic surveillance to provide better management of the infectious diseases.