Active Surveillance, Drug Resistance, and Genotypic Profiling of Staphylococcus aureus Among School-Age Children in China

Abstract

Methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization predisposes individuals for endogenous infections and is a major threat to children. Recently, oxacillin/cefoxitin-susceptible mecA-positive S. aureus (OS-MRSA) has been reported worldwide. Herein, a prospective, cross-sectional study was conducted across five schools, representing three educational stages, in Guangzhou, China. Nasal swabs from 2,375 students were cultured for S. aureus and all isolates were subjected to antibiotic susceptibility testing phenotypically and confirmed by femB and mecA genetic detection; all the isolates were classified as MSSA, MRSA, or OS-MRSA. All strains were also analyzed by multi-locus sequence typing. Among the 2,375 swabs, S. aureus was detected in 744 children (31.3%, 95% CI: 25.9–36.7%), of whom 72 had MRSA (3.0%, 95% CI: 0.6–5.4%) and 4 had OS-MRSA (0.2%, 95% CI: 0.1–0.3%), of which an oxacillin- and cefoxitin-susceptible MRSA strain was identified. The prevalence of S. aureus and MRSA was higher in younger children. The highest percentage of drug resistance of the S. aureus isolates (n = 744) was to penicillin (85.5%), followed by erythromycin (43.3%) and clidamycin (41.0%). The most prevalent sequence types (STs) were ST30, ST45, and ST188 in MSSA, accounting for 38.7% of the total isolates, whereas ST45, ST59, and ST338 accounted for 74.6% of the MRSA isolates and ST338 accounted for 50.0% of the OS-MRSA isolates. The MRSA and OS-MRSA isolates (n = 76) were grouped into three clades and one singleton, with clonal complex (CC) 45 as the most predominant linkage. The top nine multi-locus sequence typing-based CCs (CC30, CC45, CC5, CC1, CC15, CC944, CC398, CC59, CC7) represented 86.7% of all S. aureus isolates. All CC30 isolates were resistant to erythromycin and clidamycin, and almost all these isolates were also resistant to penicillin (99.2%). The CC45 and CC59 isolates exhibited high resistance rates to oxacillin at 31.5 and 59.0%, respectively. This study provides updated data valuable for designing effective control strategies to mitigate the burden of disease and to improve the adequacy of empirical antimicrobial treatments for potentially harmful infections.

Genomic Basis of Occurrence of Cryptic Resistance among Oxacillin- and Cefoxitin-Susceptible mecA -Positive Staphylococcus aureus

“…2016081029). The STs were reported in our previous studies ( 1 , 22 ), and the spa-typing and SCC mec typing were determined using the GCE website ( http://www.genomicepidemiology.org ) from sequenced genomes ( 33 ). The antibiotic susceptibility testing of all isolates was performed using the automated VITEK2 compact system (bioMérieux SA, Marcy l’Étoile, France).…”

“…Using BLAST, comparative genome analysis was performed among the parental and variant strains. The mutated genes were then confirmed using Sanger sequencing, and the mecA gene of revertants from the clinical strain was analyzed using conventional sequencing, as previously described by us ( 1 ). The sequences were aligned and further analyzed using the Qiagen CLC Genomics Workbench ( 33 ).…”

“… Staphylococcus aureus colonizes asymptomatically in approximately 30% of the human population ( 1 ) and is the leading cause of bacteremia, endocarditis, skin and soft tissue infections, bone and joint infections, and hospital-acquired infections ( 2 ). Several infectious diseases caused by S. aureus have a high mortality rate.…”

“…The auxiliary genes involved in cell wall metabolism, such as factors essential for methicillin resistance ( femX , femA , femB ), influence the level of methicillin resistance ( 21 ). In our previous studies, we identified two oxacillin- and cefoxitin-susceptible MRSA isolates belonging to sequence type (ST) 88 and ST59 without SCC mec element and with SCC mec IVa, respectively ( 1 , 22 ). In the present study, third-generation sequencing was used to analyze the complete genomic DNA and thereby investigate the mechanism underlying the naturally occurring “stealth” MRSA isolates.…”

Risk factors for antibiotic-resistant bacteria colonisation in children with chronic complex conditions

“…Staphylococcus aureus colonizes 20–40% of healthy individuals 7 , 8 ; however, data on paediatric cases are scarce. A previous study (COSACO) by our group found a prevalence of 33% for S. aureus nasal colonisation in the community among Spanish children, with a low prevalence of MRSA 9 .…”