Background: Staphylococcus aureus is a Gram-positive cocci commonly inhabiting the nasal cavity as a commensal. Methicillin-resistant type of Staphylococcus aureus results in invasive infections that are difficult to treat with regular antibiotics. This study helps us determine the prevalence of MRSA among healthcare workers who pose a potential risk of being the carriers of the MRSA strains, leading to infections in hospital patients. Materials & Methods: A descriptive cross-sectional study was conducted six months (January-June 2023 ) at a Tertiary care hospital, Ananthapuramu. A total of 100 nasal swabs from healthcare workers were collected, and Staphylococcus aureus was isolated and identified using standard conventional culture methods and biochemical tests. The isolated Staphylococcus aureus was tested for the presence of MRSA by using a cefoxitin (30 µg) disc in Muller Hinton Agar Medium by Kirby-Bauer disk diffusion method according to Clinical Laboratory Standards Institute (CLSI) guidelines. Results: Out of 100 samples, 14(14%) samples were positive for nasal carriage of Staphylococcus aureus, and 4 (4%) isolates were positive for MRSA. The prevalence of MRSA was 4% in our study among the healthcare workers. Conclusion: The study revealed the prevalence of Methicillin-Resistant Staphylococcus aureus in nasal carriers among healthcare workers as 4%, which may threaten the spread of MRSA among patients admitted to the hospital. Thus, the present study helps us highlight the need to regularly screen carriers in apparently asymptomatic healthcare workers to prevent nosocomial infections. |
With the rise of hospital-based medicine, Staphylococcus aureus quickly became a leading cause of healthcare-associated infections. Penicillin offered short-lived relief: resistance arose in the 1940s, mediated by the β-lactamase gene blaZ. The first semi-synthetic anti-staphylococcal penicillins were developed around 1960, and methicillin-resistant Staphylococcus aureus (MRSA) was observed within one year of their first clinical use 1.
MRSA was first observed among clinical isolates from patients hospitalized in the 1960s, but since the 1990s, it has spread rapidly in the community 2.
As MRSA can infect nearly any body site, effective management is best determined by the site of infection. Several novel antimicrobials have recently been developed against MRSA and are in various stages of clinical trials, including ceftaroline, ceftobiprole, dalbavancin, oritavancin, iclaprim and delafloxacin 3,4,5,6
Based on antibiotic susceptibility, methicillin resistance in Staphylococcus aureus is defined as an oxacillin minimum inhibitory concentration(MIC) of ≥4µg/mL 7. In India, the prevalence of MRSA ranges from 40-70% among S.aureus isolates, with variations observed between hospital and community settings 8
The rate of MRSA colonization among healthcare workers (HCWs) is not homogenous across the globe. Even though individual study reports on MRSA colonization exist, more pooled data is needed in India. Therefore, it is essential to evaluate the problem of MRSA colonization to develop a policy on preventive measures 9. The primary colonized site in man is the anterior nares10.
A systematic review and meta-analysis of MRSA carrier status among Indian HCWs using five databases (Scopus, PubMed-Medline, IndMed, CINAHL, and Google Scholar) from the articles published from 2008 to 2017 (10 years). STATA 13.0 with metaprop package in STATA was used to find the colonization rate. Among 2,349 HCWs, the pooled prevalence of MRSA colonization in the throat, nose, axilla, palm, fingertips, and web spaces was nine percent (CI 6%-13%; p=0.001, I 2 91.68%). The prevalence of nasal colonization of MRSA among 1,251 Indian HCWs was found to be 11% 9.
The colonization rate is low and negligible. Therefore, the hospital administrators, along with the hospital infection control committee, need to formulate a policy on periodic screening and decolonization of HCWs in high-risk areas 9
Thus, to reduce the grievance of patients who develop hospital-acquired infection due to MRSA, potent detection and treatment of MRSA nasal carriers among healthcare workers is very important.
A descriptive cross-sectional study was conducted for six months(From January to June 2023 ) at a tertiary care hospital in Ananthapuramu.
The samples collected were nasal swabs from the anterior nare using a sterile moistened swab. Each swab was rubbed five times against the anterior 1 cm of the nasal vestibular wall of both nares . A total of 100 nasal swabs from healthcare workers were collected. Staphylococcus aureus was isolated from the nasal swab samples and identified by standard conventional culture methods and biochemical tests.
The isolated Staphylococcus aureus was tested for the presence of MRSA by using a Cefoxitin (30 µg) disc in Muller Hinton Agar Medium by Kirby-Bauer disk diffusion method according to Clinical Laboratory Standards Institute (CLSI) guidelines.
An inhibition zone diameter of ≤21 mm was reported as methicillin-resistant, and ≥22 mm was reported as methicillin-sensitive 7
Quality control strains used: Positive control-MRSA ATCC 43300, Negative control: MSSA ATCC 25923
Image 1: Cefoxitin disc used to determine resistance pattern using Kirby-Bauer Disc Diffusion Method
Image 2: Nasal swab collected from anterior nares
Of the 100 samples, 14(14%) were positive for nasal carriage of Staphylococcus aureus, and 4 (4%) isolates were positive for MRSA carriers. The prevalence of MRSA was 4% in our study among the healthcare workers.
SPECIMEN |
ISOLATED ORGANISM |
NO |
PERCENTAGE% |
NASAL SWAB |
TOTAL SAMPLES COLLECTED |
100 |
- |
NASAL SWAB |
Staphylococcus aureus |
14 |
14% |
NASAL SWAB |
MRSA |
4 |
4% |
TABLE 1: TOTAL NUMBER OF MRSA DETECTED AMONG THE 14 SAMPLES THAT TESTED CULTURE POSITIVE FOR Staphylococcus aureus
Figure.1: A Graphical Prepresentation Of Data Alaysed For the Presence Of MRSA Carries Found In Nasal Swab Sample Collected From Healthcare Workers.
The prevalence of the Methicillin-resistant type of Staphylococcus aureus in our study was 4% among the healthcare workers screened under the study. This was consistent with the studies by Sassmannshausen R et al., who reported similar results to our research, i.e., the prevalence of MRSA carriers among Healthcare workers at 4.6%15
The result also showed similarity to studies with a prevalence of MRSA carriers among healthcare workers, such as the studies conducted by R.Deepashree et al. 13. which showed a prevalence of 6.5%13 and also with a study by Marie-Carmelle Elie-Turenne et al. 14 with a prevalence of MRSA isolated about 6.6% 14 among Health care worker.
Accordingly, studies with a higher prevalence of MRSA carriers among Healthcare workers were those conducted by M.Radhakrishna et al. 11 and Kalyani. K et al. 12 reported a percentage prevalence of 14.3%and 15.8%. Similar studies with higher prevalence were reported by Saito G et al. with a prevalence of 28.1%16 and Agricola Joachim et al. with a prevalence of 15.6%.
After the study, the need for active surveillance for MRSA nasal carriage among HCWs and decolonization of carriers 18 was highlighted, along with strict adherence to hand washing and infection control practices, which are also equally important18.
The prevalence of Methicillin-Resistant Staphylococcus aureus in nasal carriers among healthcare workers was 4%. Although the percentage of carriers stands at a low rate, these carriers may threaten the spread of MRSA among patients, especially in admitted critical care units like ICU, NICU, Post-operative wards, etc. After completion of our study of MRSA nasal carriers, topical application of Mupirocin ointment was advised to Healthcare workers who were found to be carriers in our study as Mupirocin is effective at removing S. aureus from the nose over a few weeks19 the prevention of nosocomial infections.
The present study helps us to highlight the need for regular screening of carriers in apparently asymptomatic Healthcare workers.