Molecular Characterization of Methicillin Resistant Staphylococcus aureus Strains Isolated from Hospitals Surfaces, Equipments and Patients in Northern Palestine

Discussion Committee: 
Dr. Ghaleb Adwan / Supervisor
Dr. Yahya Faydi / External examiner
Dr. Lubna Kharraz / Internal examiner
Dr. Ghaleb Adwan / Supervisor
Hala “Mohammad Shuaib” Abd-Alqader Shaheen
Staphylococcus aureus is considered one of the most important pathogens to humans and animals. Infections of this pathogen can be acquired through both hospital and community settings. This study aimed to investigate the contamination of environmental surfaces with MRSA in two hospitals in Northern Palestine, Rafidia Hospital (Nablus) and Thabet Thabet hospital (Tulkarm). In addition, to investigate molecular characterization of MRSA strains isolated from the patients and their environment in these hospitals and to use molecular methods to study the identity among these strains. Two hundred sixty five swabbed samples were collected from two hospitals (Rafidia Hospital, 100 environmental samples and 34 clinical and nasal swab samples; Thabet Thabet Hospital, 96 environmental samples and 35 clinical and nasal swab samples). Results showed that, 71 and 79 samples were mannitol fermenters from Rafidia hospital and Thabet Thabet hospital, respectively. Incidence of S. aureus in Rafidia hospital and Thabet Thabet hospital was 23.1% and 37.4%, respectively. The number of MRSA among S. aureus in both hospitals was 13 strains, Rafidia hospital 29% (n=9) and Thabet Thabet hospital 8.2% (n=4). Results of this research showed that these 13 strains were resistant to oxacilllin using Disk diffusion method. All strains showed mecA gene by PCR technique. These strains carried different antibiotic resistance genes including aacA-aphD (Gentamicin), erm(C) (Erythromycin and clindamycin), tetK (Tetracyclin). SCCmec typing identified that the majority (84.6%) of isolates carried SCCmec type II (n = 11), which is traditionally associated with HA-MRSA. Types I and III were not detected in this study. Strain No. 64T (7.7%) harbored SCCmec type IVa, which is traditionally associated with CA-MRSA. Strain 3HPR (7.7%) was non-typeable. Panton–Valentin leukocidin (PVL) was detected in 2 (14.3%) samples (3HPR and 4HPR) isolated from patients; PVL that was detected in 4HPR sample was associated with SCCmec type II while that was detected in 3HPR SCCmec was non-typeable. PVL genes of these positive samples were sequenced. The results also showed that ERIC PCR analysis revealed to that all the 13 MRSA had 12 different patterns. Samples 48BT and 99AT had the same pattern that were no bands under these conditions of ERIC PCR. Both samples were isolated from Thabet Thabet Hospital from environment (patient bed) and patient (nasal swab) for strains 48BT and 99AT, respectively. Three clinical and nasal swab isolates (3HPR, 4HPR and 99AT), were investigated by spa typing, indicating that the 3 isolates were clonally non related. Strains 4HPR and 99AT were belonged to clones t044 and t386, respectively, while the third strain 3HPR is new clone. The nucleotide sequences reported in this study were further registered at the GenBank database under the accession numbers ( KJ544514, KJ544515, KJ544516, KJ544517 and KJ544518). This study characterized MRSA burden in environmental surfaces, clinical samples and nostrils of some patients using conventional environmental sampling methods (e.g., swab cultures). Special attention to infection control policies, work practices, and cleaning techniques are necessary to reduce the risk potential of MRSA transmission in hospital staff and patients. The association between environmental contamination and the epidemiology of S. aureus nosocomial infections is complex and thus further investigations are needed to reach a better understanding of this relationship.
Full Text: 
Pages Count: