Varicella Hospitalizations and Community-Acquired Methicillin-Resistant Staphylococcus aureus: Seven Years of Active Surveillance

Introduction: In Mexico, universal Varicella vaccination is not part of the National Immunization Program. Community-Acquired Methicillin-Resistant Staphylococcus Aureus (CA-MRSA) infection is increasing worldwide. CA-MRSA infection in children with Varicella has scarcely been reported. Methods and Findings: From January-2012 to December-2018, we performed active surveillance for children <16 years of age hospitalized with Varicella at the Tijuana General Hospital, Mexico. To all patients with suspected bacterial super infection, a culture sampling was conducted. CA-MRSA was described and identified by both in vitro resistance to methicillin and other isoxazolyl penicillins and by identifying the gene mec-A by PCR. A total of 40 patients were enrolled. The median age at admission was 20.5 months (1-190). All but 4 (10%) were previously healthy children. None were vaccinated against Varicella. Cellulitis (with/without abscess) was the leading complication (50%), with 70% CA-MRSA identified in abscesses. Septicemia/bacteremia was present in 10 (25%), blood isolation was confirmed in seven (3 S. aureus (all CA-MRSA), 2 S. pyogenes, 1 S. pneumoniae, 1 E. coli). Conclusion: Hospitalizations by Varicella in our Hospital are not infrequent; they are associated with high morbidity and relatively low mortality. The leading complication was bacterial super infection represented by soft-tissue infections and bacteremia/septicemia mostly due to CA-MRSA. Keywords: Varicella; Methicillin-Resistant Staphylococcus Aureus (MRSA); Community Acquired Methicillin-Resistant Staphylococcus Aureus (CA-MRSA); Varicella vaccine; Antibiotic control