Molecular characterisation of PFGE non-typable methicillin-resistant Staphylococcus aureus in The Netherlands, 2007.

In 2007 in The Netherlands, 30% of all human isolates of methicillin-resistant Staphylococcus aureus (MRSA) sent to the National Institute for Public Health and the Environment could not be typed by pulsed-field gel electrophoresis (non-typable (NT)-MRSA). Molecular characterisation of the NT-MRSA isolates revealed 27 different spa types and two distinct SCCmec types, type IV and V. All NT-MRSA isolates were closely related based on spa and multi-locus sequence typing and belonged to the ST398 lineage. The rapid increase of NT-MRSA (ST398) isolates over the last years shows the importance of this relatively new clonal lineage.

Occurrence of methicillin-resistant Staphylococcus aureus in rats living on pig farms.

In The Netherlands, MRSA ST398 has emerged in hospitals and human carriers have been associated with exposure to pigs and cattle. High prevalences of MRSA ST398 in pigs and pig farmers have been determined and the transmission routes of MRSA on pig farms need to be elucidated. In the south of the Netherlands, in recent years, the black rat (Rattus rattus) has emerged as a prominent rodent on livestock farms. From March till May 2008, a survey on MRSA in rats living on livestock farms in the south of The Netherlands and the north of Belgium was conducted. In total, 40 black rats (R. rattus) and 3 brown rats (Rattus norvegicus) were collected on 12 farms including five pig farms, five poultry farms, one mixed pig and veal farm and one goat farm. MRSA ST398 was detected in black rats captured at two of the five pig farms as well as in a black rat living on the mixed pig and veal farm. From one black rat captured at another pig farm MRSA ST 97 was isolated. Considering the behaviour of rats on livestock farms, it is concluded that rats might play a role in the spread and persistence of MRSA on pig farms.

An outbreak of non-typeable MRSA within a residential care facility.

In a household setting within a residential care facility for visually and intellectually disabled people, a resident (index case) was diagnosed with dermal abscesses caused by a methicillin-resistant Staphylococcus aureus (MRSA) which was non-typeable by standard pulsed-field gel electrophoresis. All residents and staff in contact with the index case (a total of 200 people) were screened for MRSA.

High prevalence of methicillin resistant Staphylococcus aureus in pigs.

Recently methicillin resistant Staphylococcus aureus (MRSA) was isolated from pigs and pig farmers in The Netherlands. In order to assess the dissemination of MRSA in the Dutch pig population, we screened 540 pigs in 9 slaughterhouses, where a representative portion of Dutch pigs (63%) was slaughtered in 2005. We found 209 (39%) of the pigs to carry MRSA in their nares. Forty-four of 54 groups of 10 consecutive pigs (81%), each group from a different farm, and all slaughterhouses were affected. All MRSA isolates belonged to 1 clonal group, showing Multi-Locus Sequence Type 398 and closely related spa types (mainly t011, t108 and t1254). Three types of the Staphylococcal Chromosome Cassette (SCCmec) were found: III (3%), IVa (39%) and V (57%). All 44 tested isolates (1 isolate per group) were resistant to tetracycline, reflecting the high and predominant use of tetracyclines in pig husbandry. Twenty-three percent of the isolates were resistant to both erythromycin and clindamycin and 36% to kanamycin, gentamicin and tobramycin but only a single isolate was resistant to co-trimoxazole and none to ciprofloxacin and several other antibiotics. The percentage of MRSA positive pigs was significantly different among slaughterhouses and among groups within slaughterhouses, indicating a high prevalence of MRSA in pigs delivered from the farms as well as cross contamination in the slaughterhouses.

Multiple cases of familial transmission of community-acquired methicillin-resistant Staphylococcus aureus.

The worldwide emergence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) can have severe public health implications. Familial transmissions of CA-MRSA in The Netherlands were investigated. Among the families studied, two clusters of CA-MRSA could be identified. This report demonstrates that family members can serve as reservoirs of CA-MRSA which may become a serious problem in containing the spread of MRSA.

Molecular epidemiology of infections with Neisseria gonorrhoeae among visitors to a sexually transmitted diseases clinic.

OBJECTIVES: To identify determinants for plasmid-mediated resistance to penicillin (penicillinase-producing Neisseria gonorrhoeae [PPNG]) and tetracycline (tetracycline-resistant N. gonorrhoeae [TRNG]) among gonococci, to determine the distribution of bacterial characteristics, and to correlate these with antibiograms and patient characteristics. STUDY DESIGN: Gonococcal isolates from 131 patients attending a sexually transmitted diseases clinic in The Netherlands in 1994 were auxotyped and serotyped and antimicrobial susceptibility was tested. Information on patient characteristics was collected at the initial visit. RESULTS: The most prevalent serotype, IB-1 (26%), proved to be related to sexual contact with casual partners, especially commercial sex partners. In addition, IB-1 strains were associated with PPNG and displayed higher minimum inhibitory concentrations (MICs) for ceftriaxone, cefuroxime, and ciprofloxacin. Homosexual men were more often infected with nonrequiring, IB-2, and IB-6 strains than heterosexuals. These strains were very sensitive to ceftriaxone and ciprofloxacin. Overall, one strain showed decreased susceptibility to ciprofloxacin (MIC 0.5 microgram/ml), but no resistance to ceftriaxone, ciprofloxacin, or cefuroxime was observed. However, 31% of the isolates were TRNG, PPNG, or both. Determinants for these resistant strains among men were the use of antibiotics (odds ratio [OR] = 4.8, 90% confidence interval [CI] 1.3-19.1), Surinam or Morrocan origin (OR = 3.3, 90% CI 1.3-8.4), and homosexual contacts (OR = 0.1, 90% CI 0.03-0.4). CONCLUSIONS: Different types, with variable susceptibility, were associated with homosexual and commercial sexual behavior. PPNG and TRNG were more commonly isolated from antibiotic users, heterosexual individuals, and ethnic minorities. Continuous surveillance of susceptibility is needed to follow the spread of PPNG and TRNG and to detect resistance to the currently recommended agents in a timely fashion.