Screening for M[beta]L production of multidrug-resistant Pseudomonas aerugjnosa strains isolated from different clinical samples at Assiut University Hospitals

ABSTRACT

P.aeruginosa is an important cause of morbidity and mortality in immune-compromised patients. There is no single drug active against 100% of P. aeruginosa clinical isolates. Carbapenems are [beta]lactam antibiotics, presently considered as the most potent agents for treatment of MDR P. aeruginosa. During this study 90 pseudomonas strains were isolated from different sources 52 [57.78%] urine specimens 28 [31.11%] blood specimens and I 0 [11.11%] sputum specimens. All strains were subjected to microscopic examination, culture on selective medium and were tested biochemically for Catalase activity, Oxidase test, Citrate utilization test, and Gelatin liquefaction test. Antimicrobial susceptibility testing was performed using the disc diffusion method [modified Kirby-Bauer] on MH agar. MDR P. aeruginosa strains were stereotyped by standard slide agglutination test as recommended by the manufacturer's instructions. Screening for M[beta]L production of MD R P. aeruginosa was detected by Combined-disc synergy and E-test. Prevalence of both bla [IMP-1] 1 and bla [VIM-1] gene among M[beta]L producing P. aeruginosa isolates were detected by PCR. Ninety pseudomonas strains were subjected to antimicrobial susceptibility profile toward different antibiotic classes. Most P. aeruginosa isolates were sensitive in a descending order to Carbapenem; Imipenem [75.55%] and Meropenem [73.33%]> 4[th] generations Cephalosporins; Cefepime [66.6%] > Flouroquinolones; Levofloxacin [66.6%] and Ciprofloxacin [60%] >3[rd] generations Cephalosporins; Cefatriaxone [51.1%] and ceftazidime [44.44%]>Aminoglycosides; Tobramycin [37.77%] and Amikacin [24.44%]. Out of 90 isolated strains 47 [52.22%] were MDRS. MDR P. aeruginosa isolates [47 strains] were stereotyped as follow serotype O11 [12 [25.53%]], followed by serotype 05 [7[14.9%]], both O9 and O1 [6[12.7%]], both O2 and O3 [4[8.51%]], O6 [2[4.25%]] and both O4 and O7 [1[2.13%]], and four strains [8.52%] were cross-reacted with both serotypes O 5 and O 11 antibodies. Screening for M[beta]Ls production by Both Combined-disc IMP-EDT A and E test methods were positive in 19 and 20 isolates respectively, while prevalence of both bla [IMP-1] and bla[VIM1] gene among M[beta]L producing P. aeruginosa isolates were 17 [77.27%] and 14 [63.63%] positive to bla[IMP-1] and bla[VIM-1] gene respectively. In conclusion, Combined disk test [IMP-EDTA] and M[beta]L E test, were found to be very sensitive for detection of M[beta]L in P. aeruginosa isolates. Phenotypic methods for screening of M[beta]L production in P. aeruginosa strains correlate with genotypic methods [PCR]