Variety of the Structures of Staphylococcus Cassette Chromosome Mec in Coagulase- negative Staphylococci and Their Effects on Drug Resistance

Background: In the past coagulase negative staphylococcus were often seen as contaminants, but were later considered one of the most common photogenic bacteria in the hospital over the last decade Identification of beta-lactam and particularly methicillin in hospitals is of concern. The fundamental principle for the treatment of CoNS is the rapid identification of resistance mechanisms particularly their resistance to methicillin. The objective of this study is to determine the antibiotic resistance, the frequency of the mecA gene, and to determine the types of SCCmec in the CoNS isolates of from clinical isolates and control.

Study Design: Point prevalence case-control study.

Place and Duration of Study: Breast milk samples were collected from (200) patients suffering from mastitis and 106 lactational women as control whom visit center of breast examination in hospital Al- Sadder –in Najaf- Iraq, during the period from July/ 2015 to Jun/ 2016.

The standard biochemical tests were used for all isolates are coagulase, catalase, oxidase, and modified oxidase the CoNS isolates, then diagnosed by vitek -2 technique and the antibiotic sensitivity testing was carried out also by vitek-2 system. Then genomic isolate were extracted and mecA gene was detected by PCR technique, the types of SCCmec were performed by RFLP-PCR.

Results: Among the 62 breast milk isolates (50 mastitis, 12 control), identification of CoNS at the species level indicated that Staphylococcus epidermidis was the most common species, with 40 isolates, followed by Staphylococcus haemolyticus (10), Staphylococcus hominis (12).All isolates appeared had mecA gene , no one harbored SCCmec type I, 8 (12.9%) harbored SCCmec type II, 12 (19.3%) harbored SCCmec type III, 30 (48.3%) harbored SCCmec type IV and 8 (12.9%) remained non-typable. Staphylococcus epidermidis was the most isolates that harbored SCCmec type IV.

Conclusion: The results showed that CoNS revealed high percentage of resistance to methicillin, and the type III, SCCmec type was the most prevalence type of which encodes the largest number of resistance genes. The study give the information could be used in epidemiological study for preventing of infectious control in hospital and health centers.