The drug resistance and β lactamase phenotype detection of mucoid Pseudomonas aeruginosa

Abstract

Objective To investigate the drug sensitivity of mucoid Pseudomonas aeruginosa to common antibiotics and the expression of β-lactamase-resistant phenotype. Methods The specimens were inoculated onto different disks to isolate and cultivate bacteria. The antibiotic susceptibility of mucoid Pseudomonas aeruginosa isolates was detected and judged by CLSI 2013. The detection of drug resistance was done by Kirby-Bauer(K-B) method and β lactamase-resistant phenotype was detected by E-test. SPSS19.0 was used to statistic data and χ2 test was used to compare the antibiotic susceptibility between different groups. For all statistical test, a P values less than 0.05 was defined as statistically significant. Results The susceptibilities of mucoid Pseudomonas aeruginosa to the regular antibiotics were above 70%, of which the sensitivities to amikacin, to bramycin, gentamicin, imipenem and meropenem were higher than 90%. The positive rate of ampler class C β-lactamase (AmpC) was 28.3%(56/198). The drug sensitivity of positive strains was lower than that of the negative strains, and the differentiation was significant to piperacillin-tazobactam, amikacin, ceftazidime, levofloxacin, ciprofloxacin and aztreonam(χ2=3.89-14.45, all P 0.05). The positive rate of metallo-β-lactamase (MBL) was 19.7%(39/198), and the drug susceptibility of positive strains was lower than that of negative strains except gentamicin and aztreonam(χ2=4.07-15.99, all P<0.05). All the detected strains were Klebsiella pneumonia carbapenemase (KPC) negative. Conclusions The antibiotic susceptible rate of mucoid Pseudomonas aeruginosa was high, but some enzyme-produced strains were lower. The clinician should adjust medicine program by the results of laboratory.(Chin J Lab Med, 2015, 38: 865-869) Key words: Pseudomonas aeruginosa; Drug resistance, bacterial; beta-Lactamases; Microbial sensitivity tests; Phenotype