Molecular identification and antimicrobial susceptibility of Staphylococcus aureus nasal isolates from medical students in Cartagena, Colombia

Abstract

Staphylococcus aureus (SA) remains a major cause of nosocomial and community-acquired infections worldwide. Nasal carriage of this bacterium among hospital personnel constitutes an important source for nosocomial infections. A cross-sectional study enrolling the whole medical student population (n=387) of the School of Medicine at the Universidad de Cartagena, Colombia, was conducted to evaluate the carriage rates of both methicillin sensitive- and methicillin resistant-SA, the frequency of Panton-Valentine leukocidin genes in the isolates, and risk factors associated with carriage in this selected population. After signing an informed consent, participants completed a survey related to possible risk factors for colonization, and nasal swabs were collected from anterior nares. Staphylococcus aureus strains isolated from carriers were subjected to DNA extraction and PCR assays to determine the presence of MecA and Panton-Valentine leukocidin genes. Typing of the staphylococcal chromosomal cassette was performed for methicillin resistant strains. Molecular analysis was performed for only one strain per carrier. Prevalence of carriage for methicillin sensitive- and methicillin resistant-SA was 25% and 1.6% respectively. Most of the methicillin resistant isolates carried the staphylococcal chromosomal cassette type IV and the genes for Panton-Valentine leukocidin. To determine carrier types among medical students, each participant was subjected to four additional swabs, each taken two weeks apart. 9.8% persistent carriers, 53.1% intermittent carriers, and 37.1% non-carriers of SA were found. There was no association between risk factors analyzed and carriage of the bacterium. The study was conducted from April to September 2009 and found a persistent carriage of methicillin resistant-SA strains bearing the genes for Panton-Valentine leukocidin among medical students, evidencing the potential contribution of this portion of healthcare personnel either to the spread or introduction of these strains into the healthcare environment.

Staphylococcus aureus nasal carriers and the prevalence of methicillin resistant Staphylococcus aureus among medical students

“…The nasal carriage rate of MRSA in international studies in students ranged from 0% -6.7%. 3,[9][10][11]14 Amongst the Indian studies, a study by Bhaskaran reported a MRSA colonization of 8.6% among medical students while another study by Shrivastav et al 2015 reported the MRSA carriage rate to be 1.1%, which is much lower than our study. 6,15 The present study showed no significant difference in carriage rate of S.aureus and MRSA among male and female students.…”

“…Various studies have reported S.aureus nasal carriage in medical students ranging from 10%-39%. 3,6,[10][11][12][13] The colonisation rate of MRSA in the present study was found to be 12.66% amongst the medical students. The nasal carriage rate of MRSA in international studies in students ranged from 0% -6.7%.…”

“…3,6,10 Eradication of MRSA colonisation from patients and healthy carriers has been tried with topical and oral antibiotics. 11 International guidelines recommends local therapy with Mupirocin to eliminate MRSA nasal colonisation in certain groups of patients and health-care workers colonized with MRSA. However, this antibiotic is only effective at removing the bacterium from the nose over a few weeks, and recolonisation often occurs after therapy is discontinued.…”

Staphylococcus Aureus Nešiojimas Tarp Vilniaus Universiteto Medicinos Fakulteto Pirmo Kurso Studentų, Atsparumas Antimikrobiniams Vaistams Ir Nešiojimo Rizikos Veiksnių Tyrimas

“…iki 63,2 proc. [17,19,23,24,27]. Didelis šio tyrimo metu išskirtų padermių jautrumas nustatytas ir klindamicinui bei tetraciklinui (95 proc.).…”

Variación en el estado de portación nasal de Staphylococcus aureus sensibles a meticilina (SASM) en estudiantes de Bacteriología

“…Existen diversas poblaciones con riesgo de presentar infección por esta bacteria tales como: escolares, presos, personas con cáncer, personal del área de la salud, estudiantes de medicina, entre otros [13,14,15,16,17,18,19,20]. En el año 2005, Castro y cols realizaron una investigación en estudiantes de quinto semestre de Bacteriología de la Corporación Universitaria Rafael Núñez, encontrando una frecuencia de portación de S. aureus de 29,8% [21]; en 2010 se evaluó nuevamente la portación en estudiantes de Bacteriología de primero a séptimo semestre de esta institución, encontrándose una frecuencia de portación de Staphylococcus aureus sensibles a meticilina (SASM) de 14,9 % [22], debido a que no se conoce la variación de la portación en estudiantes de Bacteriología a medida que estos avanzan en los semestres y están expuestos al ambiente del laboratorio clínico, el grupo investigador decidió evaluar la variación en el estado de portación nasal de esta bacteria en estudiantes del programa de Bacteriología de la Corporación Universitaria Rafael Núñez, que fueron definidos como portadores en el año 2010.…”