Nasal colonization by methicillin-sensitive and methicillin-resistant Staphylococcus aureus among medical students

Abstract

Introduction: Nasal carriers of methicillin-resistant Staphylococcus aureus (MRSA) are common and play an important role in nosocomial infections. The prevalence rate and characterization of nasal carriers of MRSA among medical students in Jordan has not been investigated before.
 Methodology: The resistance of S. aureus to several antibiotics was tested using disc diffusion method, automatic Vitek 2, and penicillin binding protein (PBP) 2 slide test. Bacterial species and resistance genes were confirmed using molecular analysis of three relevant genes by real-time PCR. Two hundred ninety nasal swabs were collected from medical students at Hashemite University from June 2015 to August 2016. All participants signed a voluntary consent form and filled a predesigned questionnaire.
 Results: The mean age of participants was 19.7 ± 2 years and 61.7% of them were males. 63 out of the 290 (21.7%) samples were identified to have S. aureus, 56 (19.3%) were methicillin-sensitive S. aureus (MSSA) and 7 (2.4%) were MRSA. S. aureus nasal colonization significantly associates with male gender (OR = 1.7, CI = 0.94-3.18, P = 0.049) and chronic illnesses (OR = 4.0, CI = 1.52-10.65, P = 0.006). Consistency between disc diffusion, Vitek 2, and PBP 2 methods for MRSA screening were satisfactory compared to molecular analysis. All MRSA samples were positive for SCCmec:orfx junction gene (MRSA-specific), nuc gene (S. aureus- specific), mecA gene (PBP-mediated resistant), and PBP2 production. All MRSA isolates were multi-drug resistant and were sensitive to Linezolid, Vancomycin, and Tigecycline.
 Conclusions: This study confirms that nasal colonization by MRSA among medical students necessitates further attention to prevent nosocomial infections.

Nasal carriage of Staphylococcus aureus by medical students: Assessment of antibiotic susceptibility and risk factors

“…19 Research in Jordan in 2018 identified significant correlations between students with chronic disease and male gender with S. aureus carriage. 11 In Taiwan, Chen et al found correlations between hospital stay in the previous 1-year, antibiotic use and male gender with S. aureus carriage. 20 A 2017 study from China identified correlations with increased age and male gender and a significant difference with regular nasal cleaning.…”

Status of Biofilm-Forming Genes among Jordanian Nasal Carriers of Methicillin-Sensitive and Methicillin-Resistant Staphylococcus aureus

“…All participants consented to nasal swab collection and were invited to complete a questionnaire designed to comprehensively review the demographic information for every participant. The demographic data of both populations are illustrated in Tables 1 and 2 and in our previous publication [ 15 ] .…”

“…The collection of nasal swabs was carried out as described before [ 15 ] . Briefly, samples were collected under aseptic conditions, and the same swab was used for both nostrils.…”

“…Positive cultures were assessed for colony morphology, Gram stain (GCC Diagnostics, UK), and biochemical tests. Isolates were diagnosed as S. aureus if they had a typical Gram-positive cocci shape arranged in clusters and tested positive for catalase and coagulase enzymes, as well as formed yellow colonies on mannitol salt agar and creamy colonies on sheep blood agar (Biolife, Italy) [ 15 ] . All positive isolates were further analyzed using the automatic Vitek 2 compact system for Gram-positive identification (GP card, REF 21342) according to manufacturer’s instructions.…”

“…The antibiotics used were oxacillin (1 µg), cefoxitin (30 µg), and vancomycin (30 µg; Bioanalyse, UK). Antibiotic susceptibility patterns were also determined and analyzed by Vitek 2 compact system using the Gram-positive *susceptibility card (AST P592, REF 22287) according to the manufacturer’s recommendation (BioMérieux, France) [ 15 ] .…”