Contribution of active surveillance cultures to the control of hospital-acquired carbapenem-resistant Acinetobacter baumannii in an endemic hospital setting

Abstract

Background: Despite the increasing rates of carbapenem-resistant Acinetobacter baumannii (CRAB) carriage among hospitalized patients in endemic settings, the role of active surveillance cultures and cohorting is still debated. We sought to determine the long-term effect of a multifaceted infection-control intervention on the incidence of CRAB in an endemic setting.

Methods: A prospective, quasi-experimental study was performed at a 670-bed, acute-care hospital. The study consisted of 4 phases. In phase I, basic infection control measures were used. In phase II, CRAB carriers were cohorted in a single ward with dedicated nursing and enhanced environmental cleaning. In phase III large-scale screening in high-risk units was implemented. Phase IV comprised a 15-month follow-up period.

Results: During the baseline period, the mean incidence rate (IDR) of CRAB was 44 per 100,000 patient days (95% CI, 37.7-54.1). No significant decrease was observed during phase II (IDR, 40.8 per 100,000 patient days; 95% CI, 30.0-56.7; P = .97). During phase III, despite high compliance with control measures, ongoing transmission in several wards was observed and the mean IDR was 53.9 per 100,000 patient days (95% CI, 40.5-72.2; P = .55). In phase IV, following the implementation of large-scale screening, a significant decrease in the mean IDR was observed (25.8 per 100,000 patient days; 95% CI, 19.9-33.5; P = .03). An overall reduction of CRAB rate was observed between phase I and phase IV (rate ratio, 0.6; 95% CI, 0.4-0.9; P < .001).

Conclusions: The comprehensive intervention that included intensified control measures with routine active screening cultures was effective in reducing the incidence of CRAB in an endemic hospital setting.

Figure 1.

Timeline of prevention measures throughout the study period.

Figure 2.

Incidence density of clinical hospital-acquired carbapenem-resistant Acinetobacter baumannii between 2019 and 2022. Note. Phase I (January 2019–May 2020), baseline measures; phase II (June–December 2020), cohorting CRAB carriers, dedicated staff, enhanced environmental cleaning, small-scale screening; phase III (January–June 2021), cohorting CRAB carriers, dedicated staff, enhanced environmental cleaning, large-scale screening; phase IV (July 2021–September 2022), follow-up.

Figure 3.

Dendrogram carbapenem-resistant A. baumannii isolates obtained by Fourier transform infrared biotyping. The dendrogram analysis reveals that multiple clusters were simultaneously disseminated within the hospital and within the same ward. Screening samples and imported cases were involved in the spread of these clusters. Note. HA, hospital acquired.

Figure 4.

Site of carbapenem-resistant Acinetobacter baumannii carriage among patients detected by screening cultures.

Figure 5.

Mode of initial detection of carbapenem-resistant Acinetobacter baumanni, 2019–2022. Note. CRAB, carbapenem-resistant Acinetobacter baumannii; HA, hospital acquired. The numbers within the column indicate the total count of cases.