Epidemiology of methicillin-resistant staphylococci in Europe

Abstract

Methicillin-resistant staphylococci are mostly resistant not only to all beta-lactams but also to a wide range of other antibiotics, and have emerged as major nosocomial pathogens during the past two decades. Considerable variations in the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) exist between institutions and between geographic areas. In Europe, in general, a north-south gradient is observed, MRSA strains being rare in Scandinavian hospitals (<2%) and far more prevalent in Mediterranean hospitals (>40%). Whether low or high, the rates of MRSA prevalence in European countries have remained approximately the same during the last decade. Recent findings suggest that MRSA might also be emerging as a community-acquired pathogen. The first stage in the emergence of MRSA is its acquisition by methicillin-susceptible S. aureus, and the integration into its chromosome, of the mecA gene, which, together with the other mec genes, is carried on a mobile genetic element, the staphylococcal chromosomal cassette mec (SCCmec). The origin of SCCmec elements as well as the mechanisms of their acquisition remain unknown. Molecular epidemiology studies using different techniques clearly indicate that the massive geographic spread of MRSA results from the dissemination of relatively few highly epidemic clones. Five major lineages (the so-called Iberian, Brazilian, Hungarian, New York/Japan and pediatric pandemic MRSA clones) have been defined. In Europe, the Iberian clone has been reported in several countries; the Brazilian, pediatric and Hungarian clones have also been detected, but less frequently. A unique Italian clone is predominant in Italy. As with S. aureus, coagulase-negative staphylococci (CNS) represent a serious concern in hospital-acquired infections. Despite marked geographic variations, in some areas of Europe high proportions (60-70%) of CNS are methicillin resistant. The formation of biofilm is a key virulence factor of S. epidermidis, the prominent CNS pathogen, which is the most common cause of bacteremia in device-related infections. Another emerging nosocomial pathogen, S. hemolyticus, is characterized by a tendency to develop multiple antibiotic resistances, with a unique predisposition to glycopeptide resistance.

Clinical impact of MRSA in a stem cell transplant unit: analysis before, during and after an MRSA outbreak

“…1,2 There is a wide variation in MRSA rates dependant on the country examined, with prevalence rates remaining fairly constant over the last decade in many European countries. In the UK, there is a high endemic rate with a dramatic increase in the MRSA incidence since 1993 1,3 (http://www.hpa.org.uk/ infections/topics_az/staphylo). Even in those countries with a low prevalence rate, a high frequency of outbreaks may be seen, especially in the setting of the critically ill or immunosuppressed patient.…”

Methicillin Resistant Staphylococcus aureus in Pus samples

“…MRSA transmission occurs in hospitals through infected patients or staff or can be spread by patients or staff colonized MRSA [8]. mecR1 and mecI gene which is responsible for production of penicillin binding protein which has low affinity to beta lactam antibiotics is one of the mechanism explained for MRSA [9,10].…”

Molecular characteristic of Staphylococcus aureus isolates in a Chinese teaching hospital

“…The second predominant clone in HA-MRSA isolates was ST5-MRSA-II, which belonged to the New York/Japan epidemic clone. This clone was initially found in the USA and Japan (Aires de Sousa et al, 2000), and spread to Europe and Asia (Soo et al, 2005;Stefani and Varaldo, 2003). In China, in the early 2000s, the New York/Japan emerged and rapidly increased, becoming another dominant clone in our country besides Brazilian clone .…”