الفهرس 
Gram-negative bacterial pathogensOnly 14 pages are availabe for public view
 |  | from | 211 |  |  |
| | | from | 211 | | |
Abstract
In the present study, a total of 100 isolates of Gram-negative bacteria including 65 Escherichia coli and 35 Klebsiella pneumoniae were obtained from department of clinical pathology in Tanta University Hospital. The identification of the tested isolates was confirmed using microscopic, cultural as well as standard biochemical tests. All 100 isolates were tested for susceptibility to each of 13 different antimicrobials using disc diffusion method.At the species level, it was observed that the incidence of resistance among K. pneumoniae was higher than among E. coli. Among all tested antimicrobials, ceftazidime (CAZ) and aztreonam (AZT) showed the highest rate (68%) of bacterial resistance. On the other hand, the lowest incidence of resistance was recorded toward meropenem (MEM). Among the tested quinolone antimicrobials, it was found that up to 61(61%) isolates were resistant to nalidixic acid (NA) while resistance to fluoroquinolones ranged from 45% to 53%. Being the most common, NA resistant isolates were selected for further investigation of quinolone resistance among the tested isolates. or the ease of comparison, the antimicrobial susceptibility patterns of all nalidixic acid resistant isolates (61 isolates) are grouped according to number and type of exhibited resistance markers. The 61 nalidixic acid resistant isolates were grouped into 13 major resistance patterns and each pattern included subpatterns, depending upon their resistance to different antibiotics so resistance patterns of nalidixic acid resistant isolates were markedly heterogeneous.