الفهرس 
Introduction Chapter IOnly 14 pages are availabe for public view
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Abstract
The aim of this thesis was to detect the presence of any cross-resistance between
different commonly used disinfectants in the hospital environment; and any possible link
between biocide insusceptibility and antibiotic resistance. The thesis also aimed to determine
whether the acquired adaptation to biocides can co-select for antibiotic resistance in different
clinical and hospital environmental isolates.
A total of eighty-five strains were isolated from different sources in 2010. Forty-one
were isolated from different clinical specimens obtained from inpatients who acquired various
nosocomial infections; while forty-four were isolated from different environmental samples
obtained from different sources such as; air, sink, surface of the dressing table and the waste of
chlorine solution used for the disinfection of wards in the hospital.
The clinical isolates which were classified into 27 Gram negative and 14 Gram positive
strains were identified by classical microscopical and biochemical methods as follows: 1 E. coli,
6 Klebsiella spp., 1 Pr. mirabilis, 14 P. aeruginosa and 5 A. baumannii, 6 S. aureus, 5
S. epidermidis, 2 E. faecalis and 1 E. faecium. On the other hand, the environmental isolates
were classified into11 Gram negative and 33 Gram positive strains and they were identified at
least to the genus level using the classical microscopical and biochemical methods as follows: 8
Acinetobacter spp., 3 Klebsiella spp., 7 S. aureus, 12 CoNS, 6 Micrococcus spp., 7 Gram
positive rods and 1 Candida albicans.
Sixty-one selected clinical and environmental isolates were screened for their
susceptibility to the commonly used broad spectrum antibiotics in hospitals using the modified
disc agar diffusion technique. The isolates showed various resistance patterns which indicate
heterogeneity. Cefotaxime and Ceftriaxone were found to be the least active antibiotics; while
imipenem was relatively the most active one against the tested isolates. In general, it was
noticed that the clinical isolates were more resistant to antibiotics than the environmental ones.
Moreover, most of the isolates showed multi-resistance to the tested antibiotics, where 62% of
the isolates were MDR; and 11% were XDR isolates.
The bacteriostatic activities of six biocides commonly used in the hospital environment;
BK, CHX, CET, hypochlorite (Clorox®), PVPI (Betadine®) and Dettol® were screened against
66 different clinical and environmental isolates, through MIC determination by agar dilution
techniques. In general, the results showed that the Gram negative isolates were more resistant to
BK, CHX, CET and Dettol® than the Gram positive ones. On the other hand, there was no great
difference in the sensitivities of the Gram positive and the Gram negative isolates towards CRA
and PVPI. Within the same class of organisms, there was no obvious role for the source of the
isolate - whether being clinical or environmental- on the susceptibility towards biocides.