Methicillin-resistant S. aureus colonization in intensive care unit patients: Early identification and molecular typing

Abstract

Introduction: Early detection of methicillin-resistant Staphylococcus aureus (MRSA) in colonized patients is very important for infection control procedures to prevent MRSA spread. We aimed to monitor MRSA carriage in intensive care unit (ICU) patients and to evaluate the speed and efficiency of conventional culture, immunological, chromogenic, and molecular methods together with genotyping. Methodology: Nasal and axillar swab specimens were obtained from patients in the ICUs of the general surgery and neurosurgery wards in a tertiary hospital once a week over four weeks between December 2009 and July 2010. Oxacillin and cefoxitin disk diffusion tests, oxacillin agar screening test, latex agglutination test, chromogenic agar, and real-time polymerase chain reaction (PCR) tests were used for isolation and identification of MRSA. MRSA isolates were typed using ribotyping and pulsed-field gel electrophoresis (PFGE) typing. Results: MRSA colonization was detected in 48 of 306 patients by real-time PCR. The MRSA colonization rate was 6.2%, 15.5%, and 38.5% at admission and in the first and second weeks, respectively. Sensitivity, specificity, positive and negative predictive values for all phenotypic tests were 98%, 99.6%, 98%, and 99.6%, respectively. The shortest handle time was observed in PCR. A total of three banding patterns were obtained from MRSA isolates by ribotyping, and PFGE analyses revealed 17 different pulsotypes varying from 11 to 18 distinct bands, showing high genetic diversity among the samples. Conclusion: Phenotypic MRSA screening tests in our study exhibited similar performances. The superiority of real-time PCR is its short turnaround time.

Nasal colonization with methicillin-resistant Staphylococcus aureus at admission among high-risk Turkish and international patients

“…In Turkey, two studies reported 1.2% prevalence of MRSA on hospital admission [26,27]. Another recent study from Turkey identified MRSA colonization in 6.2% of intensive care unit patients on admission [28]. In our study, MRSA prevalence was 4.4% upon admission in Turkish patients from Istanbul and Kocaeli province.…”

A one-year prospective study of colonization with antimicrobial-resistant organisms on admission to a Vietnamese intensive care unit

“…aureus nasal colonization rate was 13.1% which was indeed lower than previously reported in urban and rural northern Vietnam (21.1%, 140/662) [ 12 ] and in other countries with rates of between 8.1% and 30.1% [ 13 – 16 ]. However, the prevalence of nasal MRSA colonization of 8.6% (72/838) in this study compared to proportion of MRSA colonization documented in the HTD (2.9% in 2004–2006) [ 17 ] and reported in other healthcare settings with rates of between 0.3% and 12.9% [ 14 , 18 – 22 ] may indicates that MRSA is an increasing problem that needs addressing in Vietnam. So, we do not believe that our microbiological approach resulted in significant reduction in the yield of S .…”

Effectiveness of preoperative decolonization with nasal povidone iodine in Chinese patients undergoing elective orthopedic surgery: a prospective cross-sectional study

“…In our study, the prevalence of MRSA colonization was 1.28%, and the overall rate of S. aureus in the nasal region was 13.2%. Both of these rates were lower than the nasal carriage rates reported in other studies from China or abroad ( 1 , 9 , 18 – 22 ). MRSA incidence in elective orthopedic surgery was also lower than reported incidence in other surgeries ( 23 , 24 ).…”

“…Another finding from the present study was that 7 of the patients who were positive for MSSA on the day of surgery were not positive during the pre-operative screen. The reason for this may be due to the fact that the pre-operative swabs were not sensitive enough to detect S. aureus colonization, and this might be improved by utilizing the PCR method instead of routine cultures ( 11 , 22 ) or by swabbing from multiple sites ( 15 ).…”