Five years prospective survey of antibiotic resistance in Bacteroides and Parabacteroides isolated from inpatients of clinical hospital in Warsaw, Poland

Objectives: Diagnostics of anaerobic bacterial infections and determination of drug susceptibility are technically difficult and time-consuming; therefore, the number of studies on Anaerobic Gram-negative bacilli is significantly limited, especially in Europe. The aim of the study was to analyze the antibiotic susceptibility of clinically important anaerobic bacteria Bacteroides spp. and Parabacteroides distasonis. Strains were isolated from infections of patients hospitalized at one Polish hospital as a result of routine microbiological diagnostics. Material and methods: Clinical isolates were identified with MALDI-TOF MS. Antimicrobial susceptibility of 276 strains was carried out by E-test gradient strip to commonly used antibiotics i.e. benzylpenicillin, amoxicillin with clavulanic acid, imipenem, clindamycin and metronidazole. MIC values were determined. The interpretation of antimicrobial susceptibility tests were conducted in accordance with The European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations. Results: Susceptibility tests of all isolates yielded the following rates of resistance to the evaluated β-lactam antibiotics: benzylpenicillin (96%), amoxicillin/clavulanic acid (7.6%), imipenem (2.1%). In presented study 38.8% of clindamycin-resistant strains were isolated, among them 18.3% of B. fragilis and 53.85% P. distasonis. All strain were susceptible to metronidazole. Conclusions: Obtained results and analysis of the results of other researchers convinces us that it is necessary to routinely or at least periodically monitor drug susceptibility of clinical isolates of anaerobic bacteria and use targeted therapy based on the result of the antibiogram. Although high percentage of the tested Bacteroides and Parabacteroides strains remained susceptible to metronidazole and β-lactam antibiotics the use of clindamycin in empirical therapy may not be efficacious. Antibiogram results should be consult with the staff responsible for patient treatment and hospital antibiotic policies.