Nasal carriage of Staphylococcus aureus: epidemiology, underlying mechanisms, and associated risks

Abstract

Staphylococcus aureus has long been recognized as an important pathogen in human disease. Due to an increasing number of infections caused by methicillin-resistant S. aureus (MRSA) strains, therapy has become problematic. Therefore, prevention of staphylococcal infections has become more important. Carriage of S. aureus appears to play a key role in the epidemiology and pathogenesis of infection. The ecological niches of S. aureus are the anterior nares. In healthy subjects, over time, three patterns of carriage can be distinguished: about 20% of people are persistent carriers, 60% are intermittent carriers, and approximately 20% almost never carry S. aureus. The molecular basis of the carrier state remains to be elucidated. In patients who repeatedly puncture the skin (e.g., hemodialysis or continuous ambulatory peritoneal dialysis [CAPD] patients and intravenous drug addicts) and patients with human immunodeficiency virus (HIV) infection, increased carriage rates are found. Carriage has been identified as an important risk factor for infection in patients undergoing surgery, those on hemodialysis or CAPD, those with HIV infection and AIDS, those with intravascular devices, and those colonized with MRSA. Elimination of carriage has been found to reduce the infection rates in surgical patients and those on hemodialysis and CAPD. Elimination of carriage appears to be an attractive preventive strategy in patients at risk. Further studies are needed to optimize this strategy and to define the groups at risk.

Computerized antibiogram for methicillin-resistantStaphylococcus aureus in chest surgery

“…During the study period, we established the measures against MRSA at three levels in and around chest surgery: (1) individual, (2) ward, and (3) institutional levels.…”

Aktuelle MRSA-Problematik

“…Übereinstimmend wird empfohlen, bei Risikopatienten zum Zeitpunkt der stationären Aufnahme nach einer MRSA-Besiedlung zu suchen [1,4,7,10,14]. Meist wird die Notwendigkeit von ScreeningUntersuchungen damit begründet, dass bei positivem Befund sofort spezielle Hygienemaßnahmen eingeleitet werden kön-nen, um eine Übertragung des MRSA auf andere Patienten zu verhindern.…”

Methicillin-resistente Staphylococcus aureus (MRSA) – Klinische Implikationen

“…Über eine eindeutige Korrelation zwischen einer Kolonisation mit Methicillin-sensiblen S.-aureus-Isolaten (MSSA), insbesondere der Nase, und dem Auftreten von endogenen chirurgischen Wundinfektionen wurde schon in den 50 er Jahren in verschiedenen Studien berichtet [9]. Obwohl bisher im Vergleich von MRSA zu MSSA-Stämmen keine Virulenzunterschiede, beispielsweise unterschiedliche Adhärenz, vermehrte Toxinoder Hämolysinproduktion aufgezeigt werden konnten, scheint das Infektionsrisiko bei MRSA-Besiedlung im Vergleich zur MSSA-Besiedlung um ein Vielfaches hö-her zu sein.…”