Tuberc Respir Dis.  2008 Aug;65(2):91-98.

Molecular Epidemiology and Antimicrobial Resistance of Methicillin-resistant Staphylococcus aureus Isolated from Nasal Swab at Intensive Care Unit

• Kwak OS
• Kwon MH
• Jeong JH
• Kang MI
• Cheun JY
• Lee GE
• Kim YK
• Choi EG
• Na MJ
• Kwon HU
• Son JW

Abstract

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is the most common organism associated with nosocomial infections. MRSA infections are becoming increasing important because they have emerged no only as healthcare-associated (HA) infections but also as community-associated (CA) ones. This study examined the moleculo-epidemiology of MRSA, which was isolated from nasal swabs in the intensive care unit (ICU) at Konyang University Hospital. MRSA are classified into HA-MRSA and CA-MRSA.
METHODS
From June to September 2006, 353 patients who were admitted to the ICU in Konyang University Hospital were enrolled in this study. Single nasal swabs were obtained for culture in the ICU on the 1st day. Pulsed-field gel electrophoresis and the antimicrobial resistant patterns were analyzed between HA- and CA-MRSA. An antimicrobial sensitivity test was also performed.
RESULTS
Forty two strains of MRSA were isolated from 353 patients (11.9%). Among the 42 isolates, HA-MRSA and CA-MRSA were found in 33 (78.6%), and 9 (21.4%), respectively. Eleven different PFGE types (type A to K) were identified. Types A (n=9) and B (n=7) were the most common for HA-MRSA, and types A (n=2) and B (n=2) were identified in CA-MRSA. The proportion of types A and B in CA-MRSA (44.4%) was similar to that in HA-MRSA (48.5%). The rates of resistance rates to erythromycin and ciprofloxacin were higher in HA-MRSA than in CA-MRSA.
CONCLUSION
The rate of isolation of MRSA in an ICU setting was 11.9%. HA-MRSA was isolated more frequently than CA-MRSA. The rate of resistance of HA-MRSA to erythromycin and ciprofloxacin was higher than that of CA-MRSA. Despite the small number of subjects, the main isolates (type A and B) of CA-MRSA were similar to those of HA-MRSA.

Keyword

Methicillin-resistance; Staphylococcus aureus; Pulsed-field gel electrophoresis

MeSH Terms

Ciprofloxacin
Cross Infection
Electrophoresis, Gel, Pulsed-Field
Erythromycin
Humans
Critical Care
Intensive Care Units
Methicillin Resistance
Methicillin-Resistant Staphylococcus aureus
Molecular Epidemiology
Staphylococcus aureus
Ciprofloxacin
Erythromycin

Figure

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  Figure 1 Classification of 42 MRSA isolates at Konyang University Hospital. IR: isolates rate.

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  Figure 2 PFGE image of MRSA strains with enzyme SmaI-macrorestriction. Lane 1, type D; lane 2, 4, 5, 7, type A; lane 3, type C; lane 6, type I; lane 9, type H.

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  Figure 3 Prevalence according to PFGE types of CA-MRSA and HA-MRSA.

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