Prevalence, risk factors, and epidemiology of methicillin-resistant Staphylococcus aureus carried by adults over 60 years of age.

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in the community in Portugal is not completely understood. To evaluate S. aureus and MRSA carriage among the elderly, we conducted a large cross-sectional study between April 2010 and December 2012. A total of 3,361 adults over 60 years of age were screened for S. aureus nasopharyngeal and oropharyngeal carriage. MRSA were characterized by staphylococcal cassette chromosome mec (SCCmec) typing, spa typing, multilocus sequence typing (MLST), and tested for the presence of Panton-Valentine leukocidin (PVL). Risk factors for MRSA carriage were identified by multiple logistic regression analysis. The prevalence of S. aureus and MRSA carriage among the elderly was 20.1 % and 1.8 %, respectively. The risk of being an MRSA carrier was higher among the elderly living in retirement homes [odds ratio (OR) = 2.90, 95 % confidence interval (CI): 1.48-5.48] and those that had been hospitalized in the previous year (OR = 2.64, 95 % CI: 1.47-4.58). Among the 62 MRSA isolates, 64.5 % were multidrug-resistant and none carried PVL. Most MRSA (82.3 %) were related to three hospital-associated (HA-MRSA) clones disseminated in Portugal: ST105-II (New York/Japan clone; 43.5 %), ST5-IVc (Pediatric clone; 19.4 %), and ST22-IVh (EMRSA-15 clone; 19.4 %). The New York/Japan and Pediatric clones were significantly associated with carriers living in retirement homes, while the EMRSA-15 clone was associated with carriers that had been hospitalized. We conclude that the elderly population in Portugal is essentially free of MRSA. Given the current European societal challenges for a healthy active aging, these results are of importance to healthcare professionals and public authorities to decide on strategies to promote health in this age group.

Changes in pneumococcal serotypes and antibiotypes carried by vaccinated and unvaccinated day-care centre attendees in Portugal, a country with widespread use of the seven-valent pneumococcal conjugate vaccine.

The seven-valent pneumococcal conjugate vaccine (PCV7) has been available in Portugal since June 2001, but is not included in the National Vaccination Plan. Its impact on colonization is unknown. A point-prevalence study to evaluate PCV7 usage was carried out in 2006 among day-care centre attendees from the Lisbon area. Pneumococcal carriage rates, serotypes, and antibiotypes were determined and compared with results from a similar study conducted in 2001 before vaccine approval. In 2001 and 2006, 717 and 571 children, respectively, were enrolled. In 2006, 45.9% of the participants were appropriately vaccinated and 11.5% were incompletely vaccinated. Carriage of pneumococci remained stable (64.9% in 2001; 68.7% in 2006). Vaccine types (VT) decreased from 53.1% of all pneumococci to 11.2% (p <0.001). Serotype replacement was observed among vaccinated and unvaccinated children. Non-vaccine types (NVT) 1, 6C, 7F, 15A, 16F, 21, 23A, 29, and non-typeable (NT) strains increased significantly; serotype 19A increased, but not significantly. Rates of resistance to penicillin, erythromycin, clindamycin and tetracycline remained stable (p >0.05) due to significant increases in intermediate resistance to penicillin (from 5.5% to 17.8%), erythromycin (from 9.2% to 21.8%), clindamycin (from 6.4% to 19.3%) and tetracycline (from 8.3% to 15.8%) among NVT. Whereas in 2001 resistance among NVT was mostly associated with serotype 19A and NT strains, in 2006 resistance was also found among serotypes 6C, 15A, 24F and 33F. In conclusion, dramatic shifts in serotypes of colonizing pneumococci were observed among vaccinated and unvaccinated children. Rates of antibiotic resistance remained unchanged due to a balance between reduction in VT and an increase in antimicrobial-resistant NVT.