الفهرس 
History
Nomenclature and TaxonomyOnly 14 pages are availabe for public view
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Abstract
Acinetobacter spp. has become one of the most important pathogens responsible for hospital acquired infections, especially in intensive care unit patients. Acinetobacter spp. resistant to common antimicrobial agents, including: fluoroquinolones, aminoglycosides and carbapenems, have created a challenge for appropriate therapy. The aim of the study was to determine the association between bla OXA genes carriage and in vitro antimicrobial susceptibility pattern of the pathogens to selected B-Lactams antibiotics including carbapenems.
The study was conducted on 30 suspected ß- Lactam resistant isolates of Acinetobacter spp isolated from different sites of infection including sputum 12(40%), wound 10 (33%), throat swabs 3 (10%), urine 3(10%) and blood 2 (7%) collected from Central laboratories of Ain Shams University Hospitals from March 2010 till August 2010. Most of them were isolated from the surgery ward (23%) and different ICUs (43.3%).
A.baumannii was the most frequent isolated organism (87%) and A.lwoffii (13%), detected by API. Antibiotic susceptibility for the 30 isolates was determined using broth micro dilution method, then bla OXA genes 23, 24, 51 were detected by multiplex PCR.
Tested bla OXA genes has been detected in all isolates 30 (100%), bla OXA 51 was the most common gene found 14 (47%), followed by bla OXA 23 7(23%), then bla OXA 24 9 (30%). Prevalence of bla OXA genes among A. baumannii was bla OXA 51 14 (54%), bla OXA 23 5 (19%)and bla OXA 24 7 (27%), while in A. Lwoffii bla OXA 51 was not present, bla OXA 23 2 (50%) and bla OXA 24 2 (50%).
There was a statistically significant difference regarding the duration of ICU stay and the infection with Acinetobacter carrying bla OXA 23 or bla OXA 51 or bla OXA 24. Also, there was a high statistical significant value regarding the insertion of intra vascular catheter and the infection with Acinetobacter carrying bla OXA genes. About 93% of Acinetobacter spp carrying bla OXA 51 were isolated from patients with intra vascular devices. On the other hand those isolates carrying bla OXA 23 and bla OXA 24 were detected from patients without intra vascular catheter. No statistically significant difference appeared regarding the age, type of infection, insertion of urinary catheter, surgical procedures in previous 30 days and mechanical ventilation and the infection with Acinetobacter.
As regards the resistance pattern of isolates 100% to ceftazidime, 83% to levofloxacin, 80% to amikacin, 67% to ampicillin/sulbactam, 57% meropenem while only 23% to colistin, showing that the presence of bla OXA genes among Acinetobacter spp. was significantly correlated with the resistance to all β-lactam antibiotics tested. As regards the species types 65% of A.baumannii were resistant to meropenem while all of A. Lwoffii was sensitive. About 96% of A. baumannii were resistant to levofloxacin while all of A. Lwoffii was sensitive. On the other hand there was no statistically significant value detected among the different antibiotic susceptibility patterns and bla OXA gene present among Acinetobacter spp except in amikacin (Aminoglycosides). About 71.4% of those carrying bla OXA 51 were resistant, 100% carrying bla OXA 24 were resistant and 71% of those carrying bla OXA 23 were resistant.
Most of the isolates showed multiple drug resistance showing the marked relation between multidrug resistance (MDR) phenotype and bla OXA presence among the 30 studied isolates.