<p>Antibiotic susceptibility profile and prevalence of <em>mecA</em> and <em>lukS-PV/lukF-PV</em> genes in <em>Staphylococcus aureus</em> isolated from nasal and pharyngeal sources of medical students in Ecuador</p>

Abstract

Background Staphylococcus aureus is a common nasal colonizer in 20–30% of the general population. When mucosal and cutaneous barriers are disrupted, S. aureus can cause severe infections. While MRSA nasal carriers have an increased risk of infections when compared to non-carriers, prolonged exposure to the hospital environment may cause an increase in carriage of MRSA. Materials and methods A survey questionnaire was filled for analyzing risk factors of colonization. Swab isolates were identified as S. aureus by traditional microbiological assays. Antibiotic susceptibility profiles were performed following the CLSI standard guidelines. Multiplex PCR was conducted to determine the presence of genes mecA and lukS-PV/lukF-PV . Chi-squared, univariate, and multivariate logistic regressions were applied to find statistically significant associations between risk factors and the presence of S. aureus and MRSA. Results One hundred and eighty-six isolates were identified as S. aureus . The strains showed high resistance to penicillin, oxacillin, azithromycin, erythromycin, clindamycin (inducible), and tetracycline. The overall prevalence of MRSA in medical students was 45.9% [40.4–51.6] 95% CI. PCR showed a prevalence of mecA gene in MRSA isolates of 6.1% while lukS-PV/lukF-PV gene was present in 3.2% [1.2–6.9] 95% CI of the S. aureus samples. The risk factors frequency of antibiotic intake and repeated visits to hospitals demonstrated statistical significance. Conclusion S. aureus and MRSA isolates have a high prevalence of colonization, and antibiotic resistance in the population studied. MRSA resistance was not related to the presence of the mecA gene. The prevalence of PVL genes was low, but it could represent a risk because they are circulating in the community.

Methicillin-Resistant Staphylococcus aureus Nasal Colonization Among Health Care Workers of a Tertiary Hospital in Ecuador and Associated Risk Factors

“…This finding is in line with previous researchers in Brazil and Ethiopia, who reported 5.1% and 5.8% of MRSA colonization respectively. 18 , 23 In Ecuador, the prevalence of MRSA, detected in this study, was higher than a previous study carried out in Quito 10 that reported a prevalence of 2.4% but lower than the study into medical students 19 that reported a 7.1% prevalence of MRSA. A similar prevalence was demonstrated in other Latin American countries, such as Argentina, where a study in hospitals showed that the overall MRSA acquisition rate was 2.3/1000 patient-days-at-risk with a MRSA acquisition prevalence of 1.96% 24 Of course, there are studies that have shown a much higher MRSA colonization prevalence.…”

“… 18 Another study in Quito in 2019 reported an even higher colonization rate of 57.8% (186/322) among medical students. 19 However, it should be mentioned that the 2019 study in Quito involved nasal and throat swabs, whereas our study only analyzed nasal swabs. Some studies have shown that pharyngeal colonization can be higher than nasal colonization.…”

Genomic Characterization of Methicillin-Resistant Staphylococcus aureus (MRSA) by High-Throughput Sequencing in a Tertiary Care Hospital

“…Of more interest, the PVL-encoding genes detected in this work were all from non-severe cases, and no blood, tissue or ETA specimens had isolates that were PVL-positive. Association of PVL with non-severe cases has been recognized [ 31 , 32 ], but the reverse was also sporadically reported [ 33 ].…”

Reduced Susceptibility to Chlorhexidine among Staphylococcus aureus Isolates in Israel: Phenotypic and Genotypic Tolerance

“…A comparison with other studies concluded that pvl prevalence among S. aureus isolates varies between geographical areas or the type of patients (e.g., children vs. adults) [ 33 ], from 3% to 75% [ 34 , 35 , 36 ]. Interestingly, the majority of pvl -positive strains in our study were MRSA, an observation that aligns with earlier reports [ 33 , 37 , 38 , 39 ]. For example, a study performed in Alaska in 2000 reported that while no MSSA isolates carried the pvl genes, 92% of MRSA isolates had the toxin [ 39 ].…”