الفهرس 
Intensive care acquired infectionOnly 14 pages are availabe for public view
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Abstract
Nosocomial outbreaks of MDR infections in hospitals have led to endemic occurrence of these infections, with dissemination of resistance genes, plasmids and strains of a variety of bacterial species. MDR enterobacteria often produce ESBL or overexpress AmpC β-lactamases. However, many clinical microbiologists are unaware of plasmid-encoded AmpC because its phenotypic detection is difficult, as these β-lactamases can be misidentified as ESBLs.
The CLSI recommend ESBL screening and confirmation only for E.coli isolates, which is an organism with constitutive or minimal AmpC chromosomal expression, and K.oxytoca, K.pneumoniae and P.mirabilis, which have no chromosomally encoded AmpC. In addition, there are no CLSI recommendations for detecting AmpC in any species.
This study aimed to compare boronic acid and cloxacillin as inhibitor based test for detection of AmpC enzymes in Gram negative bacilli.
The present study was conducted at ICUs of ASUHs during the period from April 2011 till December 2011.The study included 50 patients admitted to different ICUs, suffering from nosocomial catheter associated urinary tract infection 16 samples (32%), surgical site infection 8 samples (16%), burn wound infection 7samples (14%), ventilator associated pneumonia 4 samples (8%) and catheter associated blood stream infection 15 samples (30%). The age of the patients ranged from 18 years to 72 years old and mean age of 47 years. They were 27 (54٪) males and 23 (46٪) females.
The present study revealed the following results:
Among 54 isolated microorganisms, (30%) were P. aeruoginosa followed by, E.coli (26%), A.baumannii (22%), P. mirabilis (13%) and K.pneumoniae (9%).
The most effective antibiotics against P.aeruoginosa were cefepime (26%) and azetronam (26%).
The most effective antibiotics against E.coli were piperacillin-tazobactam (72%) and amikacin (72%) followed by trimethoprime-sulfamethoxazole (58%), piperacillin (51%). For E.coli isolated from urine the most effective antibiotics were cephalothine (88%) and nitrofurantoin (88%).
The most effective antibiotic against A.baummanii was tetracycline (66%) followed by trimethoprime-sulfamethoxazole (34%), gentamycin (25%) and amikacin (25%).
The most effective antibiotics against P.mirabilis were piperacillin-tazobactam (86%) and cefoxitine (86%) followed by gentamycin (72%), ceftriaxone (72%) and ciprofloxacine (72%).
The most effective antibiotic against K.pneumoniae was imipenem (100%) followed by gentamycin (60%), piperacillin-tazobactam (40%) and cefoxitine (20%).
Among 54 isolated microorganisms, (50%) were AmpC positive only,(13%) were ESBL positive only, (17%)were both AmpC & ESBL positive and (20%) were both AmpC &ESBL negative.
Among 54 isolated microorganisms, (67%) were Amp C positive and (33%) were negative. And among positive AmpC cases (n=36) the most frequent organism was E.coli (85.7%) then P.aeuroginosa, P.mirabilis, A.baumannii and K.pneumoniae.
Among 54 isolated microorganisms, (30%) were ESBL positive and (70%) were negative and among positive ESBL cases (n=16) the most frequent organism was K.pneumonia (60%), then E.coli, A.baumannii, P.aeuroginosa and P. mirabilis.
Cefotaxime with clavulanic acid was better than ceftazidime with clavulanic acid for the detection of ESBL production in different species (Pearson Chi- Square Value is 0.582, P. Value is 0.446).
Detection of AmpC production in different species by cefoxitin with cloxacillin (55.5%) was better than other different methods (44.5%) (Pearson Chi- Square Value is 16.738, P. Value is 0.001).