ABSTRACT
Carbapenemases are B-lactamases which include serine B-lactamases andmetallo B-lactamases [MBLs]
Their production is the most important mechanisms of microbial resistance to [beta]-lactam antibiotics
Modified Hodge test is a phenotypic method for detection ofcarbapenemases. EDTA disk synergy [EDS] test is used for detection of MBLs. AmpC disk test is the commonly used tests for detection of AmpC [betaj-lactamases. Detection of genes coding for carbapenem resistance by PCR, usually give reliable and satisfactory results, but this method is of limited practical use for daily application in clinical laboratories because of the cost. This study was conducted over a period of ten months [July 2012 to April 2013] at the Medical Microbiology and Immunology Department, Faculty of Medicine, Tanta University. A total of 110 Acinetobacter species and 120 Pseudomonas species were included in this study
These organisms were isolated from specimens like aspirated synovial fluid from knee infective arthritis, sputum, tracheal aspirate, pus, urine, blood, pleural fluid and ascitic fluid of patients admitted to Internal Medicine, Chest, ENT, Orthopaedic and Urology Departments, Faculty of Medicine, Tanta University
The Acinetobacter species and Pseudomonas species were identified and screened for meropenem resistance by Kirby-Bauer method. The meropenem resistant strains were subjected to modified Hodge test for detection of carbapenemases. EDTA disk synergy [EDS] test was done with simultaneous testing of two different [beta]-lactams [meropenem and ceftazidime], for detection of metallo-[beta]-lactamases in the meropenem resistant isolates. AmpC disk test was also done for the meropenem resistant strains for detection of AmpC [betaj-lactamases. Of the 110 clinical isolates of Acinetobacter species, 82 were A. baumannii, while 28 were A. Iwoffli. Among the 120 Pseudomonas isolates screened, 91 were Ps. aeruginosa, while the remaining 29 were other Pseudomonas spp. Forty two [51.0%] A. baumannii, 8 [31.8%] A. Iwoffii, 29 [31.8%] Ps. aeruginosa and 8 [27.6%] Pseudomonas spp. were found resistant to meropenem. Among the 29 meropenem resistant Ps. aeruginosa, 13 [44.8%] were AmpC [beta]-lactamase producers, 15 [51.7%] were MBL producers by EDTA disk synergy test, but only 10 [34.4%] were positive for carbapenemases by modified Hodge test. Of the 8 meropenem resistant Pseudomonas spp., 5 [62.5%] were AmpC [beta]-lactamase producers, 2 [25.0%] were MBL producers by EDTA disk synergy test, but only 1 [12.5%] was positive for carbapenemases by modified Hodge test
Among the 42 meropenem resistant A. baumannii, 32 [76.2%] were AmpC [beta]-lactamase producers, 3 [7.1%] were MBL producers, but only 2 [4.8%] was positive for carbapenemases by modified Hodge test
Of the 8 meropenem resistant A. Iwoffii, 3 [37.5%] were AmpC [beta]-lactamase producers, and 2 [25.0 %] were positive for MBL that were detected only using EDTA-ceftazidime combination and no carbapenemases were detected by modified Hodge test. EDS is a more sensitive diagnostic method for detection of MBLs. The modified hodge test is not considered a useful screening test for carbapenemases as many MBL producing isolates were not detected by this test, while EDS is a more sensitive diagnostic method for detection of MBLs. AmpC B- lactamase is a major factor for carbapenemases resistance among the isolates in the hospital
ABSTRACT
Widespread use of ciprofloxacin in treatment of urinary tract infection [UTI] led to increased level of resistance in clinical isolates of E. coli. The aim of this study was to investigate the molecular characterization of ciprofloxacin resistant E.coli isolates from community acquired urinary tract infections.. E-coli strains were isolated from urine samples [E. coli represented 70% of isolates [21/30] and minimal inhibitory concentration [MIC] of Ciprofloxacin [CFX] of E. coli was measured [Resistant strains of E. coli had MICs of ciprofloxacin ranging from 4 to >32 mg per liter]. CFX resistant E. coli strains were subjected to PCR to amplify gyrA and parC genes of Quinolones resistance determining region of E. coli. DNA sequencing of amplified product was carried out and the molecular characterization of E. coli resistant to CFX were analysed [All resistant E. coli isolates contained Ser83+/-Leu and Asn87+/-Asp mutations in gyrA and a Ser83-+/-Ile mutation in parC; two isolates also contained a Glu84+/-Val mutation in parC.