RESUMO
Objective To compare the difference of three methods testing the antibiotic susceptibility of mucoid Pseudomonas aeruginosa in order to provide accurate and reliable antibiotic susceptibility result for clinic.Methods A total of 630 mucoid Pseudomonas aeruginosa were collected from Linyi People′s Hospital during January 2015 to December 2016.They mainly come from respiratory medicine and the most common specimen source was sputum.All specimens were examined in 2 h.The strains isolated from the same patient were discarded.Antibiotic susceptibility was tested by the automatic microorganism analyzer VITEK2 compact, E-test, which was reference method, and K-B disk.The results of three methods were analyzed and compared by χ2 test.Results The result of E-test showed that antibiotic sensitivity of 630 mucoid Pseudomonas aeruginosa was above 52.7% except for Cefepime (39.2%).The result of K-B disk was compared with E-test, the antibiotic sensitivity of mucoid Pseudomonas aeruginosa to imipenem (72.4% vs 52.7%) and amikacin (48.6% vs 71.1%)had significant difference (χ2=8.283 7 and 10.533 8, P<0.05).The result of VITEK2 compact showed that the antibiotic susceptibility of mucoid Pseudomonas aeruginosa to imipenem(70.8% vs 52.7%), cefepime(60.8% vs 39.2%), gentamicin (87.6% vs 74.1%)and levofloxacin(81.3% vs 65.4%) was significant higher than the result of E-test (χ2=6.935 2,9.331 2,5.885 6 and 6.466 5, P<0.05).For tobramycin, piperacillin/tazobactam and ciprofloxacin, the result of three methods is more consistent.Compared to VITEK2 compact, the consistency between K-B disk and E-test was higher.The rate of very major error and major error were between 0.0%-4.8% (Amikacin 12.2%) and minor error was 4.6%-20.3%.Conclusions The drug sensitivity of mucoid Pseudomonas aeruginosa is different between various methods.The result of K-B disk and E-test using blood MH is more reliable than VITEK2 compact.
RESUMO
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 x2 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 (x2 =3.89-14.45,all P ＜0.05).The positive rate of extended spectrum β-lactamase(ESBLs) was 10.6％ (21/198).The drug sensitivity to ceftazidime and aztreonam of positive strains[42.9％ (9/21) and 57.1％ (12/21),respectively].It was lower than that of the negative strains [73.5％ (130/177) and 72.3％ (128/177)],x2 =5.06 and 19.24,both P ＜ 0.05.The difference of the other antibiotics was not significant(x2 =0.01-3.47,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(x2 =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.