Nasal Carriage of Staphylococcus aureus in Botucatu, Brazil: A Population-Based Survey

Abstract

Recent increases in the incidence and severity of staphylococcal infections renewed interest in studies that assess the burden of asymptomatic carriage of Staphylococcus aureus in the community setting. We conducted a population-based survey in the city of Botucatu, Brazil (122,000 inhabitants), in order to identify the prevalence of nasal carriage of Staphylococcus aureus (including methicillin-resistant strains). Nasal swabs were obtained from 686 persons over one year of age. Resistance to methicillin was assessed through phenotypic methods, identification of the mecA gene and typing of the Staphylococcal Chromosome Cassette mec (SCCmec). Methicillin-resistant S. aureus (MRSA) isolates were characterized using Pulsed-Field Gel Electrophoresis (PFGE), Multilocus Sequence Typing (MLST) and spa typing. Polymerase chain reaction was applied to identify genes coding for Panton-Valentine Leukocidin (PVL) in isolates. The prevalence of overall S. aureus carriage was 32.7% (95%CI, 29.2%–36.2%). Carriers were significantly younger (mean age, 28.1 versus 36.3 for non-carriers; OR for age, 0.98; 95%CI, 0.97–0.99) and likely to report recent skin infection (OR, 1.85; 95%CI, 1.03–3.34). Carriage of methicillin-resistant S. aureus (MRSA) was found in 0.9% of study subjects (95%CI, 0.4%–1.8%). All MRSA isolates harbored SCCmec type IV, and belonged to spa types t002 or t021, but none among them harbored genes coding for PLV. In MLST, most isolates belonged to clones ST5 or ST1776. However, we found one subject who carried a novel clone, ST2594. Two out of six MRSA carriers had household contacts colonized with isolates similar to theirs. Our study pointed to dissemination of community-associated MRSA among the Brazilian population.

Molecular epidemiology of methicillin‐resistant Staphylococcus aureus in the Brazilian primary health care system

“…Similar results have been reported in other studies [34,35]. A low frequency of the PVL gene was also observed in other studies conducted in the region [22,35,36].…”

“…These results agree with the findings of a population-based study conducted in Botucatu in 2011 aimed at identifying the prevalence of S. aureus in nasal carriers. The study demonstrated a prevalence of MRSA of 0.9%, all of them SCCmec type IV and PVL À and most isolates belonging to ST5 and ST1176 and spa type t002 [22]. ST1176 was described for the first time in S. aureus SCCmec IV in a study conducted at Hospital São Paulo in the city of São Paulo, Brazil, indicating the emergence of this new clone (ST-1776) as the causative agent of community-acquired and nosocomial infections in Brazil hla (2), hlb (2), hld (2), icaA (2), icaD (2) BHU14 (1); BHU3 (1) 2…”

Prevalence and characterisation of Staphylococcus aureus causing community‐acquired skin and soft tissue infections on Java and Bali, Indonesia

“…According to the multivariate analysis, nasopharyngeal S. aureus carriage was associated with S. aureus SSTI, a finding similar to that in multiple previous studies on S. aureus carriage . Decolonisation may therefore be beneficial in such cases.…”

Nasopharyngeal carriage of Staphylococcus aureus among imprisoned males from Brazil without exposure to healthcare: risk factors and molecular characterization

“…In that study, 32.7% and 0.9% of persons carried S. aureus and MRSA, respectively [9]. Even though these findings are somewhat puzzling, some remarks should be made regarding the study subjects.…”