Prevalence of Nasal Carriage of Methicillin-Resistant Staphylococcus aureus among Healthcare Workers of Intensive Care Unit in Four Hospitals in Nicaragua

Background: The intensive care unit (ICU) is a high risk area for patients, where some bacterias such as methicillin-resistant Staphylococcus aureus (MRSA) are usual pathogens involved in healthcare associated infections. It is so far known that healthcare workers (HCW) could be reservoirs of MRSA thru nasal colonization.  In Nicaragua, the knowledge about the prevalence of colonization of MRSA in HCW of the ICUs is limited.

Objective: The aim of this study is to determine the prevalence of nasal carriage of MRSA among HCW of the ICU in four hospitals at Managua, capital city of Nicaragua.  Additionally were evaluated associations of prevalence of nasal colonization with MRSA and background of upper respiratory tract infections, previous usage of antibiotics, and the characteristics of the job of the HCW.  The antimicrobial susceptibility of the isolates of MRSA is described.

Methods: A descriptive study of prevalence was performed from January to May of 2010. Anterior nasal swabs were taken from 77 HCW of a total of 78, in the ICUs of the Hospital Metropolitano Vivian Pellas, Hospital Roberto Calderón, Hospital Bautista, and Hospital Antonio Lenín Fonseca.  The nasal swabs were inoculated and incubated in sheep blood agar McConkey Agar at 35˚C for 72 hours. Final identification of S. aureus and antibiotic susceptibility was performed with autoSCAN. All the procedures were performed following CLSI guidelines.

Results: The prevalence of nasal carriage of S. aureus in HCW was 24.7%, and the prevalence of MRSA was 16.8%. The highest prevalence of nasal colonization of MRSA in HCW was found in the Hospital Roberto Calderón (26.3%) that according with their own hospital epidemiology surveillance has a high rate of healthcare associated infections in ICU with the involvement of MRSA.  There were not significant associations between nasal colonization of MRSA and previous upper respiratory tract infections, usage of antibiotics, and some characteristics of the job of the HCW.  The isolates of MRSA were susceptible to vancomycin and linezolid (100%), and tetracycline (92%).  The proportion of strains of MRSA susceptibles to ciprofloxacin (30%) and clindamycin (15%) were very low.

Conclusions: The prevalence of nasal carriage of MRSA among HCW in the ICUs of four hospitals in Nicaragua is high in comparison with other studies. The isolated strains of MRSA were highly resistant to ciprofloxacin and clindamycin.