ABSTRACT
Extended spectrum beta -lactamases [ESBLs] and AmpC beta -lactamases are enzymes produced by a variety of Gram-negative bacteria which confer an increased resistance to commonly used antibiotics and represent a substantial clinical threat. Several phenotypic tests have been recommended for screening and confirmation of ESBL- and AmpC-producing organisms. However, a comprehensive diagnostic algorithm integrating both screening and confirmation has not been established. This study aimed to detect ESBL and/or AmpC production by using MastD68C ESBL and AmpC detection set as a single phenotypic method and to study its sensitivity and specificity comparing to other methods. Evaluate the effect of novel antibiotics namely tigecycline and doripenem, as well as the efficacy of old reviving antibiotics as colistin and temocillin against ESBL- and AmpC-producing Enterobacteriaecae. Hundred Enterobacteriaceae isolates were screened for ESBL production using disc diffusion method and confirmed by combination disc diffusion test. Screening of AmpC production was done by cefoxitin disc test, disc approximation test and confirmation was done by AmpC disc test. Isolates screened positive for ESBL were investigated for their susceptibility to temocillin, tigecycline, colistin and doripenem by E-test. Among the 100 Enterobacteriaceae isolates, 45 were screened positive for ESBL-production using the disc diffusion test and 36 were confirmed by the combination disc test. Nine isolates were screened for AmpCproduction using the cefoxitin disc test and 5 isolates were confirmed as AmpC producers by AmpC disc test. Using MAST D68C set, 35 isolates were ESBL producers, 2 were AmpC producers, one isolate was both ESBL and AmpC producer. All isolates were sensitive to tigecycline and doripenem. Forty-three isolates were sensitive to colistin, while, thirty-seven isolates were sensitive to temocillin. MAST D68C test appears to be a promising way to detect isolates producing ESBL and/or AmpC. Tigecycline, doripenem, temocillin and colistin revealed excellent activity against ESBL- and AmpC- producing Enterobacteriaceae