Antibiotic resistance and bro genotyping of Branhemella catarrhalis isolated from patients with lower respiratory tract infections in Linyi, Shandong province

Abstract

Objective To analyze the antibiotic resistance of Branhemella catarrhalis strains isolated from sputum specimens of patients with lower respiratory tract infections from Linyi, Shandong Province, and to explore the relationship between bro genotypes of the strains and their resistance to antibiotic agents. Methods Sputum specimens were colleted from the patients with lower respiratory tract infections in Linyi People's Hospital from the January 2010 to December 2014. The specimens were inoculated into 4 different disks for bacterial isolation and cultivation. β- lactamase detection and drug sensitivity tests were performed, and PCR coupled with restriction endonuclease analysis was employed for bro genotyping. χ2 test was used to compare drug resistance of strains with different bro genotypes. Results A total of 497 Branhemella catarrhalis strains were isolated in five years, among which 221 strains were isolated in winter. All strains were sensitive to ertapenem and chloramphenicol, and the resistance rates to amoxicillin/clavulanate and cefaclor were low (≤2.8%). The strains were highly resistant to compound sulfamethoxazole, erythromycin and ampicillin (47.6%-89.8%), and there was a trend of increasing resistance rates with the year, but no statistically significant difference was observed (P>0.05). β-lactamases was positive in 412 strains (82.9%), and all of these strains were positive for bro gene, and the resistances to erythromycin, compound sulfamethoxazole, levofloxacin and ampicillin were higher in bro positive strains than those in bro negative strains (χ2=12.16, 16.18, 8.41 and 200.00, P 0.05). Conclusions Most of Branhemella catarrhalis clinical isolates are β-lactamase producing strains, and bro-1 is the most common genotype. Strains are highly sensitive to carbapenems, cephalosporins and β-Lactamaseinhibitors, which can be recommended for the treatment of Branhemella catarrhalis-related respiratory tract infections. Key words: Respiratory tract infection; Branhemella catarrhalis; beta-Lactamases; Microbial sensitivity tests; bro gene