ABSTRACT
Objective:To explore the resistance of common clinical isolates to chlorhexidine gluconate (CHG) and the clinical characteristics of patients with the infections.Methods:A total of 1 000 isolates from the First Affiliated Hospital of Wenzhou Medical University in 2018 (from January to May) were collected, which included 200 strains each of Escherichia coli ( E. coli), Acinetobacter baumanii ( A. baumanii), Pseudomonas aeruginosa ( P. aeruginosa), Staphylococcus aureus ( S. aureus), and Enterococcus spp.. Minimum inhibitory concentration (MIC) of CHG against 1 000 isolates were determined by the agar dilution method. The correlation between the resistance of isolates and clinical characteristics of infected patients was analyzed. Chi-square test or Fisher exact probability test were used for statistical analysis. Results:A total of 57 CHG resistant strains were detected in 1 000 clinical isolates. These CHG-resistant strains were mainly isolated from sputum and intensive care unit ward, accounting for 49.1%(28/57)and 38.6%(22/57), respectively. The resistance rates of P. aeruginosa, A. baumanii, Enterococcus spp., S. aureus, and E. coli to CHG were 16.0%(32/200), 7.0%(14/200), 3.0%(6/200), 1.5%(3/200) and 1.0%(2/200), respectively. The CHG-resistant rates of P. aeruginosa to ceftazidime, ciprofloxacin, levofloxacin and gentamicin were 53.1%(17/32), 78.1%(25/32), 65.6%(21/32) and 50.0%(16/32), respectively, which were all higher than those of CHG-sensitive P. aeruginosa (25.0%(8/32), 25.0%(8/32), 21.9%(7/32) and 15.6%(5/32), respectively), with statistical significance ( χ2=5.317, 18.080, 12.444 and 8.576, respectively, all P<0.05). The hospital mortality was 22.8%(13/57) in patients infected with CHG-resistant bacteria, which was higher than that in patients infected with CHG-sensitive bacteria ((7.0%(4/57); Fisher exact probability test, P=0.018)). CHG-resistant group had a higher history of CHG exposure and antimicrobial treatment (61.4%(35/57) and 70.2%(40/57), respectively), which were both higher than those with CHG-susceptible isolates (17.5%(10/57) and 47.4%(27/57), respectively), the differences were both statistically significant ( χ2=22.947 and 6.118, respectively, both P<0.05). In addition, the multi-drug resistance rate of CHG-resistant strains was 54.4%(31/57), which was higher than that of CHG-susceptible strains (35.1%(20/57)), the difference was statistically significant ( χ2=4.293, P=0.039). Conclusions:CHG resistant strains have higher antimicrobial resistance. Hospital mortality in patients infected with CHG-resistant bacteria is higher than patients infected with CHG-sensitive bacteria. The important risk factors are CHG exposure and antimicrobial therapy.
ABSTRACT
Objective@#To evaluate the in vitro antibiotic effects of colistin combined with meropenem, levofloxacin or fosfomycin against colistin-heteroresistant Acinetobacter baumannii (A.baumannii).@*Methods@#A total of 576 A. baumannii clinical isolates were collected from the First Affiliated Hospital of Wenzhou Medical University from 2014 to 2015. Minimal inhibitory concentrations (MICs) of colistin against A. baumannii were detected by broth dilution method. Colistin-heteroresistant A. baumannii isolates were screened using population analysis profiles (PAPs). MICs of colistin combined with meropenem, levofloxacin or fosfomycin, and the four drugs used alone against colistin-heteroresistant A. baumannii were detected by checkerboard method and broth dilution method. Fractional inhibitory concentration index (FICI) was calculated to evaluate antibiotic effects.@*Results@#None of the 576 A. baumannii isolates was resistant to colistin as indicated by the broth dilution method. Nine colistin-heteroresistant A. baumannii isolates were identified using PAPs. Compared with the MICs of colistin used alone, the MICs of colistin used in combination with meropenem, levofloxacin or fosfomycin against colistin-heteroresistant isolates were all decreased. Colistin-meropenem combination showed synergistic (55.6%), additive (33.3%) and indifferent effects (11.1%), but no antagonistic effect. Colistin-levofloxacin combination showed synergistic (55.6%), additive (22.2%) and indifferent effects (22.2%), but no antagonistic effect. Colistin-fosfomycin combination showed synergistic (77.8%) and additive (22.2%) effects, but no indifferent or antagonistic effect.@*Conclusion@#In vitro use of colistin in combination with meropenem, levofloxacin or fosfomycin has synergistic and additive antibacterial effects against colistin-heteroresistant A. baumannii. Combinations of colistin-meropenem and colistin-levofloxacin have fewer indifferent effects and no antagonistic effect.
