Longitudinal analysis of endemic gentamicin- and tobramycin-resistant gram-negative bacilli in a community hospital

The epidemiology of endemic gentamicin- and tobramycin-resistant gram-negative bacilli at a community hospital was analyzed over a one-year period three years following an original analysis at the same hospital. The frequency and distribution of resistant organisms remained stable over the time spanning the two studies. Only 2.8% of all gram-negative bacilli were resistant to gentamicin or tobramycin, and the majority of resistant isolates were non-Enterobacteriaceae. The respiratory and urinary tracts remained the body sites most prone to harbor resistant organisms. Risk analysis using a matched comparison group again revealed prior treatment with an aminoglycoside to be the only significant factor pre-disposing to acquisition of resistant gram-negative bacilli. This analysis indicates that community hospitals may not be important reservoirs of endemic aminoglycoside-resistant gram-negative bacilli, and reconfirms the observation that each hospital must define its own pattern of aminoglycoside resistance and unique risk factors.