(B-237) Risk factors for Staphylococcus aureus (S. aureus) and Methicillin-resistant Staphylococcus aureus (MRSA) carriage in children: a case-control study

Background: Staphylococcus aureus is a type of commensal bacteria that has the potential to elevate the risk of staphylococcal infections, particularly in children with compromised immune systems. Prolonged colonization in children may result in severe invasive bacterial infections. Transmission of S. aureus between caregiver and children may occur via intimate personal interactions within household.

Objectives: To investigate the epidemiology and risk factors associated with bacterial carriages of S. aureus and MRSA in Hong Kong children and adolescents through the analysis of sample collection of nasal swab results.

Methods: We recruited children and adolescents, aged 0-18 years and their caregivers during clinical visit at Hong Kong Children’s Hospital specialist out-patient clinic. We obtained nasal swabs during visits from participant pairs along with surveys completed by caregivers providing information on recent antibiotic usage, travel and infection history. Bacterial colonization testing was conducted upon receiving the samples. Children with S. aureus colonization were cases, while those without colonization served as controls. Risk factors were analyzed using logistic regression models.

Results: Of all 306 subjects, 83 were case (27.1%); 3.9% were MRSA carriers; with 55.2% were male; mean age 6.82; 48.6% had prior antibiotic use; 62.4% had prior pneumococcal vaccination; 85% had respiratory symptoms.
Male gender, younger age and larger household size were associated with a lower risk of S. aureus and MRSA colonization (OR: 0.76, 95% CI: 0.40-1.4; OR: 0.13, 95% CI: 0.02-0.76; OR: 0.51, 95% CI:0.25-1.03). After adjusting for sex and age group, significant risk factors for S. aureus carriage in children included caregiver who used antibiotics within 12 months (OR: 2.26, 95% CI: 1.04-5.33), caregivers having S. aureus colonization (OR: 3.85, 95% CI: 2.07-7.23), caregiver with chronic conditions (OR: 2.28, 95% CI: 1.06-4.84). For the child MRSA carriage, significant risk factors identified were found, caregiver with chronic conditions (OR: 8.02, 95% CI: 1.74-39.78) and caregiver having MRSA colonization (OR: 18.29, 95% CI: 1.19-233.9).

Conclusions: The prevalence of S. aureus and MRSA carriage has been found to be higher than previously documented. The results demonstrate that children colonization is significantly associated with caregiver antibiotics usage history and chronic condition history. The risk factors identified in this study will contribute valuable insights towards understanding the characteristics of children at increased risk for carrying S. aureus and MRSA.