Haemophilus influenzae Vulvovaginitis in Prepubertal Girls: A 4-Year Study on a Tertiary Children’s Hospital in China

Abstract

Background: Vulvovaginitis is a common infection in prepubertal girls, which is partly caused by bacterial infection. According to the literature, Haemophilus influenzae is one of the most common bacterial causes of vulvovaginitis in children. However, few studies with large sample sizes have delved into this issue. Objectives: To determine the prevalence of Haemophilus influenzae vulvovaginitis in prepubertal girls and detect the antimicrobial resistance of H. influenzae strains isolated from vulval specimens. Methods: The isolates of H. influenzae from the vulval swabs of prepubertal girls with vulvovaginitis were received from The Children’s Hospital, Zhejiang University School of Medicine, during 2016 - 2019. The vulval specimens were inoculated on Haemophilus selective chocolate agar, and antimicrobial susceptibility tests were performed by the disk diffusion method. Moreover, β-lactamase was detected using Cefinase disc. Results: In this study, 4142 vulval specimens were received during four years, of which 649 H. influenzae isolates had been isolated from 642 girls aged 6 months-13 years, with a median of 5 years. The peaks of isolates were observed from April to July in the vulval isolates. In general, the ampicillin resistance rate was 39.1% (250/640), 33.2% of strains (211/636) were β-lactamase-positive isolates, and 6.6% strains (42/635) were β-lactamase-negative ampicillin-resistant (BLNAR) isolates. The resistance rates of H. influenzae isolates to amoxycillin-clavulanic acid, ampicillin-sulbactam, cefuroxime, ceftriaxone, cefotaxime, meropenem, levofloxacin, sulfamethoxazole-trimethoprim, azithromycin, and chloramphenicol were 26.4%, 21.8%, 24.8%, 1.7%, 1.0%, 0.2%, 0%, 47.7%, 10.2%, and 1.1%, respectively. Multi-drug resistance (MDR) was noticed in 41 persons (6.4%) out of the 642 H. influenzae isolates, with the most prevalent MDR phenotype of ampicillin-sulfamethoxazole-trimethoprim-azithromycin resistance. Conclusions: Clinicians should noticed that H. influenzae is a common bacterial cause of vulvovaginitis in children, and laboratories should routinely cover Haemophilus culture media for vulval specimens. The ampicillin resistance of H. influenzae should also be considered in clinical management.