Comparison between phenotype and molecular resistance characteristic in Staphylococcus epidermidis isolates from wound infections in Al-Basrah province, Iraq

Background:Staphylococcus epidermidis is considered the upper respiratory tract's human skin flora and mucosal membrane and displays low pathogenic capacity in healthy individuals. Drug-resistant strains can be identified as a natural result of the microflora through antibiotic therapy and are a possible cause of pathogenic strain resistance genes. Methods:Culture, biochemical analysis and Vitek2 Utilizing for identified the One hundred and fifty swab sample was collected from different wounds infected. S. epidermidis strain's ability to resist antibiotics was tested using a disk diffusion method. Result of antibiotic sensitivity test was confirmed and supported by Vitek2 system. Also, the PCR antibiotic resistance gene was detected. Results: Out of 150 swab samples, twelve were positive for S. epidermidis.. Disc method was shown the 75%,66.7%,83.3% and 58.3% harboured highest prevalence of antimicrobial resistance against penicillin, oxacillin, cefoxitin and erythromycin respectively.While the moderate prevalence 50.7%,41.7% and 33.3% of resistance against tetracycline,clandomycin and ciprofloxacin respectively. Furthermore, lowest incidence was shown the 25% for both of resistance against rifampin, and gentamycin. The Vitek2 system was confirmed and support antibiotic sensitivity test. A most frequently found antibiotic resistance genes amongst S. epidermidis strains, according to the findings, were mecA (91.7%), blaZ (91.7) , ermA (16.7%),ermB (25%),ermC (25%), tetM (25%), tetK (33.3 %) and aacA-aphD (41.7%) respectively. All S. epidermidis strain doesn't have ,vanA and vanB antibiotic resistance gene. Conclusion:Frequency of resistance to antibiotic should be detected more than one method , and used the Vitek2 system detected the antibiotic resistance gave better support for result. Additional PCR technique, actually very important to detect antibiotic resistance genes of S. epidermidis strains.


Introduction
Staphylococci are popular bacterial colonizers of human and other mammalian skin and mucosal membranes.It major Gram-positive opportunistic bacteria that have a variety of pathogenic species [1][2]. As essential nosocomial pathogens, coagulase-negative staphylococci have been increasingly recognized [3]. Primarily Staphylococcus epidermidis, are associated with human skin flora and upper respiratory tract mucosal membranes, and have in stable individuals, commensals have a low pathogenic risk [4].
Even then, in immunocompromised patients, S. epidermidis can be responsible for some serious infection [5]. Furthermore, drug-resistant pathogens can be selected as a normal part of the microflora during antibiotic therapy and are a possible reservoir for pathogenic strains resistance genes [6-7-8-9]. Infections of the prosthetic bone, artery graft, surgical site, central nervous system shunt, operation wounds, and heart system, among other things, have been linked to S. epidermidis [2].
There is no clear genetic difference between pathogenic and commensal S.epidermidis strains, and nosocomial strains are rich in virulence and antibiotic resistance genes.It has been indicated that such genes are mobilized between and within species inside the companion genome pool [10][11]. There is few available information on the molecular epidemiology of S.epidermidis strains existing in Iraq. Therefore, The current study looked into the incidence rate, antimicrobial resistance properties, and the distribution of S. epidermidis virulence factors. Isolated wound infection strains from Al-Basrah province, Iraq.

Collection of specimens
One hundred and fifty swab sample was collected from surgical wounds, gunshot wound wounds, burn wounds, puncture wounds, sliced wounds, lacerated wounds, and diabetic foot infection wounds through October-2018 to December-2018 in Al-Basrah province, Iraq.

Isolation and identification
Positive swab cultured was purification by repeating sub-cultivation to acquire single colonies in pure culture, After that Gram-stain, catalase, slide coagulase test, motility test , mannitol salt agar, blood agar hemolysis, nitrate reductase and urease test was used to identifying the bacterial isolates [12] .The identification of isolates was confirmed by Vitek ® 2 system.

DNA Extraction
The DNA Presto Mini g DNA Bacteria kit (Geneaid, USA) was used for genomic DNA extraction. The DNA sample was regarded pure, when the rate between 1.8 -2.0 ng.

PCR screening of antibiotic resistance
PCR analysis was used to examine the emergence of antibiotic resistance genes in bacterial isolates table(1).
The ermC gene was found in some strains of S.epidermidis. The aminoglycosides resistance is more common encoded by aacA-aphD (69.59 %). Due to the fact that gene normally widely distributed amongst staphylococci human origin [31].According to [32], the ermA, tetK,ermC, vatA, vatB, vatC and tetM, aacA-aphD were found in 30.90 %, 76.40 %, 74.50 %, 74.50 %, 1.80 %, 0 %, 5.50 % and16.40 %, of staphylococci strains isolated from human infection. The frequency of resistance to much more seven types of antibiotics was found to be 17.39 % in a study of [21]. Frequency of resistance to antibiotic should be detected more than one method , and used the Vitek ® 2 system detected the antibiotic resistance gave better support for result. Additional PCR technique, actually very important to detect antibiotic resistance genes of S. epidermidis strains.