The child was treated empirically

The child was treated empirically with oral amoxicillin–clavulanate (45 mg/kg/day). Blood culture taken at admission grew after 27 hours of incubation. Following the positive blood culture, treatment was switched to intravenous ceftriaxone (50 mg/kg/day). Susceptibility testing showed that the isolate was sensitive to all tested EZ Cap Reagent AG [penicillin (minimum inhibitory concentration 0.012 μg/mL), cefotaxime (<0.016 μg/mL), chloramphenicol, cotrimoxazole, erythromycin, clindamycin, and levofloxacin]. The child became afebrile 1 day after antibiotic treatment—3 days of ceftriaxone and 7 days of oral amoxicillin–clavulanate. The isolate from the patient was identified as serotype 19A. Multilocus sequence typing showed that the bacterium belonged to ST1201. In our locality, invasive disease caused by serotype 19A has been found to increase shortly after the availability of PCV7 and was associated with expansion of the multidrug-resistant ST320 clone. Until now, the ST1201 serotype 19A clone has mainly been detected in Europe and none has been found in Asia (Multi Locus Sequence Typing database at , access on July 27, 2013). In Spain, it is one of the circulating antibiotic-susceptible clones. Immunological studies have shown that after a booster dose in the 2 year of life, the proportions of PCV7- and PCV10-immunized children with opsonization assay (OPA) ≥ 8 against 19A were 30% and 50%, respectively. By contrast, 98–100% of children immunized with the PCV13 vaccine had OPA titers ≥ 8 after receiving the booster. The present report demonstrates that bacteremic serotype 19A infection can occur in children fully immunized with PCV10. Clinicians should bear this possibility in mind when managing febrile children suspected to be suffering from bacteremia.
Conflicts of interest

This work was supported by a block grant from the Research Fund for the Control of Infectious Diseases of the Health and Food Bureau of the Hong Kong SAR Government. We thank the parents for giving written consent to publication.