الفهرس 
Introduction and Aim of the workOnly 14 pages are availabe for public view
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Abstract
Acinetobacter spp. have emerged as one of the most important
pathogens involved in health care associated infections in recent decades,
characterized by their ability to accumulate different mechanisms of
antimicrobial resistance, often showing a multidrug-resistant phenotype.
It is necessary to distinguish between Acinetobacter baumannii group
and Acinetobacter outside the Acinetobacter baumannii group since the
latter organisms rarely have infection control implications. In addition,
these organisms are usually susceptible to a range of antimicrobials, and
infections caused by these organisms are most often benign.
Acinetobacter baumanii is rapidly becoming a focus of significant
attention, as it is the most frequent among Acientobacter species,
responsible for ventilator-associated pneumonia and bloodstream infection
which tend to be the most severe. Acinetobacter can also cause, skin and
wound infections, urinary tract infection.
Carbapenems are considered important antimicrobial agents for
treating infections due to multidrug-resistant Acinetobacter spp. However,
reports of resistance to these drugs have emerged, with increasing
frequency, among Acinetobacter spp. clinical isolates.
Modified Hodge test is a simple test which can be performed in the
routine lab for detection of carbapenemases in isolates showing
intermediate or sensitive zone diameter on disc diffusion. Methods for
gene identification are polymerase chain reaction and DNA probing.
PCR has beeen successfully utilized for the detection of single or
multiple carbapenemase genes directly from clinical samples. Obvious advantages include a greater speed of detection and potentially a higher
sensitivity than that offered by culture. Disadvantages include a higher cost
for processing samples and the need for specialized equipment and/or
expertise.
In this study, 172 isolates of Acinetobacter spp. isolated from
clinical specimens submitted to Microbiology Central Laboratory of Ain
Shams University Hospitals, were collected after antibiotic susceptibility
testing was done. All isolates were imipenem-resistant. The isolates were
subjected to API 20 NE identification system and modified Hodge test
(MHT) for detection of carbapenemase producing strains.
According to the results of API 20 NE identification, 124 of the
isolates were A. baumannii (72%) and 48 were A. loweffii (28%). Out of
the 124 A. baumanni isolates.
According to the type of specimen, 68(39.5%) out of 172
Acinetobacter species were collected from sputum, classified into 44
(35.5%) out of 124 Acinetobacter baumannii isolates, and 24 (50%) out
of 48 Acinetobacter Loweffii isolates. 50 (40%) out of 124 A. baumannii
isolates were positive for MHT (carbapenemase producing), while 74
(60%) were negative (non carbapenemase producing). It was also detected
that out of the 50 positive modified Hodge test Acinetobacter baumanii
isolates with carbapenems resistance, 32 (64%) isolates were expressing
OXA 23 gene.
Fluoroquinolones have remained active against sporadic Acinetobacter
spp. strains but resistance is now widespread among epidemic
Acinetobacter spp. strains, rendering these antimicrobial drugs no longer useful. Aminoglycosides, in particular tobramycin and amikacin, often retain their activity against resistant Acinetobacter spp. isolates; however,
these compounds are rarely used alone andare more often applied in
combination with other antimicrobials.
Colistin is now considered to be the final drug capable of treating
infections caused by carbapenem-resistant A. baumannii, however, strains
are now being isolated that are resistant to this antibiotic as well.
The emergence of multidrug- resistant A. baumannii clones in Ain
Shams University Hospitals, point to the necessity of a screening
programme for patients after hospitalization, and strict infection control
regimes to prevent further antimicrobial- resistance selection and
subsequent dissemination.
Standard infection control precautions targeting all organisms such
as hand hygiene and scrupulous environmental cleaning, education of
personnel, screening of intensive care unit patients for carbapenemresistant
A. baumannii and cohorting of patients should be stringently
adhered to in order to reduce the risk of transfer of such resistance genes.
Appropriate antimicrobial use is an integral component of any
program to slow the emergence and spread of antimicrobial-resistant
microorganisms in the healthcare setting. The optimal methods to reduce
inappropriate or excessive antimicrobial use will differ by institution.
Judicious use of carbapenems must also be advocated, as widespread use
of such agents may also create an environment favouring the inter-species
transfer as well as the overt expression of these genes.