Impact of hospital-wide infection rate, invasive procedures use and antimicrobial consumption on bacterial resistance inside an intensive care unit.

We performed a 30-month ecological study to determine the impact of hospital-wide antibiotic consumption, invasive procedure use and hospital-acquired infections (HAIs) on antibiotic resistance in an intensive care unit (ICU). Microbiological isolates from ICU patients with established diagnosis of hospital infection were monitored throughout the study. Overall hospital consumption per 100 patient-days of piperacillin-tazobactam, fluoroquinolones and cephalosporins increased from 1.9 to 2.3 defined daily doses (DDD) (P<0.01), from 4.7 to 10.3 DDD (P<0.01) and from 12.1 to 16.4 DDD (P<0.01), respectively. Bacterial multiresistance in ICU was identified in 31.3% (N=466) of isolates, with increasing resistance demonstrated for meropenem-resistant Klebsiella spp. (P=0.01) and meropenem-resistant Acinetobacter spp. (P=0.02). There was a positive correlation between multiresistance rate and DDD of cephalosporins (P<0.01) and fluoroquinolones (P=0.03). The rate of ceftazidime-resistant Klebsiella spp. correlated with DDD of fluoroquinolones and cephalosporins; the rate of ceftazidime-resistant Pseudomonas spp. correlated with consumption of cephalosporins, and rate of meticillin-resistant Staphylococcus aureus (MRSA) correlated with fluoroquinolone use. During the studied period, 36.9% (P<0.001) and 34.5% (P<0.01) of the changing multiresistance rate in ICU was associated with use of invasive procedures and overall HAI rate, respectively. Multiresistance rates in ICU are influenced by the variation in overall HAI rate, hospital-wide invasive procedures and antibiotic consumption outside the ICU.