Risk and timing of acquisition of multi drug resistant Acinetobacter baumannii in respiratory secretions of hospitalized patients at Lebanese tertiary care center

Abstract

Introduction: Multi-drug resistant Acinetobacter baumannii (MDR-AB) is a leading cause of nosocomial infections in many countries including Lebanon. The burden is mostly seen in the intensive care units (ICU), but rarely assessed in other medical wards. The objectives of this study were to investigate the dynamics of MDR-AB carriage in the tracheal secretions and its relation to predisposing factors in the various clinical settings. Method: A cross sectional study was done from Jan. till Oct. 2014. All patients with more than 48 hours of admission to the ICU and to one of our medical wards were enrolled, their medical records were reviewed and a data collection sheet was filled. The sputum of patients was cultured using two types of media; then followed up, for a positive culture, every third day during their hospital stay. Results: The study included 217 patients; 56 from the ICU and 161 from the medical floor. On the medical wards, 46 patients were sputum productive, out of which 23 were successfully followed up. Only 5 patients grew MDR-AB; 4 of them had a prior ICU stay and one patient carried MDR-AB in his sputum, without ICU exposure or development of pneumonia. On the ICU wards, 28 subjects were identified as colonizers; 19 out 55 patients (33.9%) had MDR-AB in their sputum at 48 hours of hospitalization, this percentage increased to 53.8% (7 out of 13) at day 8. The mean time for acquisition was 16.41± 2.91 days, the risk of growing MDR-AB increased when secretion status was reported as heavy (76%). As for risk factors, the decreased consciousness, mechanical ventilation, and lung opacity were clearly associated with MDR-AB colonization (p< 0.001). Besides the exposure to antimicrobial and steroids (p<0.05). The two culture media used correlated very well, the chromogenic media showed 95.2% sensitivity and 94.4% specificity when compared to MacConkey. Conclusion: The MDR-AB infection is mainly an ICU problem. Its acquisition was highly associated with length of hospital stay, decreased mental status, mechanical ventilation, heavy tracheal secretions, and extensive exposure to antimicrobial agents and steroids. The chromogenic media revealed efficacy in terms of faster screening and early identification of MDR-AB cases in the population at risk.