Epidemiology and antibiotic sensitivity of Staphylococcus aureus nasal carriage in children in Hungary

Abstract

The aim of this study was to assess the Staphylococcus aureus nasal carriage rate in healthy children all over Hungary and to specify some risk factors, the antibiotic resistance patterns of the bacteria, and their genetic relatedness. In total, 878 children (aged 3-6 years) were screened at 21 day-care centers in 16 different cities in Hungary, between February 2009 and December 2011. Samples taken from both nostrils were cultured on blood agar, and suspected S. aureus isolates were identified by β-hemolysis, catalase positivity, clump test, and nucA PCR. Methicillin-resistant strains were screened by mecA and mecC PCR. Antibiotic susceptibility was determined by agar dilution or gradient test strips. Pulsed-field gel electrophoresis was used for genotyping. S. aureus carriage rate was found to be 21.3%, which correlates well with international data. We found no statistically significant correlation between the gender or the sibling status and S. aureus carriage. All isolates were sensitive to oxacillin, trimethoprim-sulfamethoxazole, and mupirocin. The resistance rates for erythromycin, ciprofloxacin, clindamycin, gentamicin, and tetracycline were 7.5%, 0.5%, 1.1%, 3.7%, and 4.3%, respectively. The isolates showed very high genetic diversity. In summary, carried S. aureus isolates are more sensitive to antibiotics compared with clinical isolates in Hungary, and methicillin-resistant S. aureus carriage rate is very low yet.

Co-carriage of Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis among three different age categories of children in Hungary

“…Carrying S. aureus has a higher likelihood in an environment where other S. aureus carriers are present (e.g. having siblings attending another community) [62,63] as was documented also by us before [18] and now confirmed again. Recent antibiotic exposure can have a two-sided effect: it can facilitate the selection and spread of antibiotic resistant bacteria but can lead to the eradication of susceptible isolates [64][65][66][67].…”

“…As for the other risk factors, male gender has often been associated with S. aureus carriage [62,63]. This was also found in one of our previous projects [39], but not in another [18]. In the current study, the association was only statistically significant among school-age children, but not for the combined data (S1 Table and Table 3).…”

“…Furthermore, although there was a positive association between the carriage of S. pneumoniae and either of the other two species, it was independent of the fact, whether it was a VT or NVT pneumococcus ( Table 2). The S. aureus rate has increased from 21.3% to 30.1% among DCC children, compared to our study from 2009-2011 (18). The direct effect is indisputable, mirrored by the low ratio of PCV13 serotypes (6.2% in average, Table 4).…”

“…We can also compare the current results with our previous findings. Between 2009 and 2011, we had screened 878 healthy children attending DCCs in 16 different cities of Hungary and we obtained an S. aureus carriage rate of 21.3% [18]. In 2012 we have conducted a survey, screening all children at the DCCs of one town (n = 1390) and here we found a higher carriage rate (34.1%) [39].…”

“…Species-specific PCR was applied for the genotypical identification of each bacterium. The following gene targets were used: nucA for S. aureus, lytA for S. pneumoniae, ompP2 for H. influenzae and 16S rRNA for M. catarrhalis [18][19][20][21]. MecA was simultaneously detected with nucA in an in-house duplex PCR to screen for methicillin-resistant S. aureus isolates [18].…”