Division of Infection Medicine, Lund University, Lund, Sweden.
Department of Translational Medicine, Infectious Disease Research Unit, Lund University, Malmö, Sweden.
J Hosp Infect. 2020 Aug;105(4):752-756. doi: 10.1016/j.jhin.2020.05.040. Epub 2020 Jun 1.
Streptococcus pyogenes is a well-known cause of postpartum infections and is causing significant morbidity and mortality.
To describe measures taken to control an outbreak of postpartum infections caused by S. pyogenes emm75 on a maternity ward.
Patients presenting postpartum with signs and symptoms of infection were cultured for β-haemolytic streptococci with cervical swabs and blood cultures, and bacterial isolates were species-determined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and emm-typed. Pharyngeal swabs were taken from healthcare workers (HCWs) at the ward. Bacterial isolates were subjected to whole-genome sequencing (WGS). The multi-locus sequence type and the number of single nucleotide polymorphisms (SNPs) compared to an index genome were determined.
During a three-month period, six cases of postpartum infection with S. pyogenes emm75 were identified on the maternity ward. By comparing delivery dates with duty rotas, one HCW was identified as a possible source of infection in five cases. After repeated pharyngeal swabs from this individual, an S. pyogenes emm75 was isolated. The five isolates from patients epidemiologically linked to the HCW and the two isolates of the family members had an identical sequence type (ST49) and 0-2 SNPs difference compared to the HCW isolate, whereas the sixth patient had an unrelated isolate. Eradication antibiotic therapy with clindamycin and rifampicin was given to the carrier. All patients received intravenous antibiotic treatment and recovered.
A three-month outbreak was stopped when a carrier was identified and treated. Source identification and WGS proved vital for outbreak control.
化脓性链球菌是产后感染的已知原因，会导致严重的发病率和死亡率。
描述在产科病房控制由emm75 型化脓性链球菌引起的产后感染爆发所采取的措施。
对出现产后感染症状和体征的患者进行宫颈拭子和血培养，培养β-溶血性链球菌，并使用基质辅助激光解吸/电离飞行时间质谱和 emm 分型对细菌分离株进行种属鉴定。从病房的医护人员（HCWs）中采集咽拭子。对细菌分离株进行全基因组测序（WGS）。与参考基因组相比，确定多位点序列型和单核苷酸多态性（SNP）的数量。
在三个月的时间里，在产科病房发现了六例产后感染emm75 型化脓性链球菌的病例。通过比较分娩日期和轮班表，确定一名 HCW 可能是五例感染病例的传染源。对该个体反复进行咽拭子检测后，分离出一株 emm75 型化脓性链球菌。与 HCW 分离株相比，与该 HCW 具有流行病学联系的五例患者分离株和两名家庭成员的分离株的序列型（ST49）完全相同，只有 0-2 个 SNP 差异，而第六例患者的分离株则不同。对携带菌给予克林霉素和利福平的消除抗生素治疗。所有患者均接受静脉抗生素治疗并康复。
当确定并治疗了一名携带菌时，为期三个月的爆发得到了控制。传染源的识别和 WGS 对爆发控制至关重要。
