Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, 425 S. Euclid Ave., Campus Box 8118, St. Louis, MO, 63110, USA.
Eur J Clin Microbiol Infect Dis. 2024 Nov;43(11):2137-2146. doi: 10.1007/s10096-024-04927-3. Epub 2024 Sep 5.
Haemophilus influenzae (HINF), primarily non-typeable H. influenzae: (NTHi), is an important cause of neonatal sepsis and meningitis. The goal of this study was to investigate the point prevalence of HINF vaginal-rectal carriage in pregnant women, which could impact neonatal health.
Simulated vaginal-rectal swabs were cultured and tested to establish optimal recovery methods for HINF. These methods were then applied to vaginal-rectal swabs from a prospective cohort of pregnant women (n = 300) undergoing routine Group B Streptococcus: (GBS) screening. Both culture and PCR were used for detection of HINF. Subject demographics, reproductive history, and genitourinary test results were documented. A retrospective surveillance study was conducted to determine incidence of invasive neonatal HINF infections from 7/1/2017-6/30/2023.
HINF was recovered from 42/42 (100%) simulated vaginal-rectal swabs at 2-45 CFU/plate via direct plating onto chocolate and chocolate + bacitracin agar. HINF was rarely recovered following LIM broth enrichment at 0-75 CFU/plate in 1/42 (2.4%) simulated swabs, but was recovered from BHI/Fildes broth enrichment in 22/42 (52%) specimens at high abundance (> 100 CFU/plate). Among pregnant women prospectively screened for HINF, the median age was 29 (IQR, 24-33) years and gestational age was 36 (IQR, 34-36) weeks. HINF was recovered in 1 of 300 prospective specimens by culture but 0/100 by PCR. A six-year retrospective analysis showed there were seven total cases of neonatal sepsis and majority of HINF was isolated from respiratory specimens followed by blood/CSF overall.
This study established a sensitive culture method for recovering HINF from vaginal-rectal swab specimens and demonstrated low prevalence of HINF carriage rate in pregnant women. These findings highlight the need for further research to pinpoint the source for transmission of HINF to neonates.
流感嗜血杆菌（HINF），主要是非分型流感嗜血杆菌（NTHi），是新生儿败血症和脑膜炎的重要病因。本研究旨在调查孕妇阴道直肠携带 HINF 的时点患病率，这可能会影响新生儿健康。
模拟阴道直肠拭子进行培养和检测，以建立 HINF 最佳回收方法。然后将这些方法应用于接受常规 B 组链球菌（GBS）筛查的前瞻性孕妇队列（n=300）的阴道直肠拭子。使用培养和 PCR 检测 HINF。记录受试者的人口统计学、生殖史和泌尿生殖系统检查结果。进行回顾性监测研究，以确定 2017 年 7 月 1 日至 2023 年 6 月 30 日期间侵袭性新生儿 HINF 感染的发生率。
通过直接接种巧克力琼脂和巧克力+杆菌肽琼脂，从 42/42（100%）模拟阴道直肠拭子中回收了 42/42（100%）HINF，每个平板回收 2-45CFU。在 1/42（2.4%）模拟拭子中，LIM 肉汤富集后很少回收 HINF，为 0-75CFU/平板，但在 22/42（52%）标本中，BHI/Fildes 肉汤富集后大量回收（>100CFU/平板）。在前瞻性筛查 HINF 的孕妇中，中位年龄为 29（IQR，24-33）岁，孕龄为 36（IQR，34-36）周。通过培养从 300 例前瞻性标本中回收了 1 例 HINF，但通过 PCR 未回收 1 例。六年回顾性分析显示，共有 7 例新生儿败血症病例，大多数 HINF 分离自呼吸道标本，其次是血液/CSF 总体。
本研究建立了一种从阴道直肠拭子标本中回收 HINF 的敏感培养方法，并证实孕妇 HINF 携带率低。这些发现强调需要进一步研究以确定 HINF 向新生儿传播的来源。
