Do changes in ICU flora and their antibiotic susceptibility parallel changes in infection control and antibiotic use?

Introduction

The usefulness of microbiological surveillance in ICU patients is under debate [1, 2]. It can signal infection/colonization sites, most frequent germs and their antibiotic susceptibility. Our study aimed to investigate changes in the microorganism rate and their antibiotic susceptibility in ICU patients along with efforts to change antibiotic practice and infection control policies in the ICU.

Methods

A prospective study was performed in a 19-bed mixed ICU in an emergency university hospital. Blood, catheters, respiratory secretions, surgical wound secretions and urine were cultured any time in the case of infection suspicion or every 4 to 5 days in the case of patients with ICU length of stay >5 days. Cultures were counted no matter the infection or colonization status. Antibiotic use was recorded as daily drug doses/100 beds (DDDs). The study included two time periods: January to June 2007 (P1 – 839 admitted patients) and January to June 2008 (P2 – 779 admitted patients). Comparison between the two periods included overall and site-specific rates of positive cultures, patterns of germs, antibiotic susceptibility and antibiotic usage.

Results

The overall number of positive cultures decreased by 31.8% (P < 0.01) and per patient by 15% (P < 0.01) in P2 versus P1. Germ patterns changed little over time, most frequently found being Staphylococcus aureus, Acinetobacter spp, coagulase-negative staphylococci and Pseudomonas spp. According to the site, coagulase-negative staphylococci isolated from the bloodstream decreased from 42% to 26% (P = 0.01), but Acinetobacter spp. in the respiratory tract increased from 34.5% to 43%, concurrently with a reduction in Klebsiella spp from 12.7% to 3%. Antibiotic use decreased by one-half in P2 versus P1 (68.7 DDDs vs. 113.8 DDDs, P = 0.01). Ciprofloxacin dropped from first (P1) to seventh (P2) position (75% decrease) and resulted in a decrease in ciprofloxacin resistance of S. aureus from 94% to 46% (P < 0.01).

Conclusion

Changes in infection control policies and antibiotic use resulted in a decreased number of positive cultures in ICU patients and a decline in antibiotic resistance in some strains.