Muturi Peter, Mbae Cecilia, Kibet Evans, Njoroge Peter, Kavai Susan M, Ideke Darius, Jepchirchir Jessicah, Gunn John S, Kariuki Samuel
Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya.
Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, United States.
Front Microbiol. 2025 Jun 25;16:1628784. doi: 10.3389/fmicb.2025.1628784. eCollection 2025.
Non-typhoidal infections are a significant global public health concern, causing approximately 150 million illnesses and 60,000 deaths annually, with majority of the cases occurring in low- and middle-income countries. In this study, we used whole genome sequencing to identify and characterize uncommon non-typhoidal serovars isolated from patients presenting with gastrointestinal symptoms in the Mukuru area of Nairobi, Kenya. Sixteen less common NTS serovars (excluding Typhimurium and . Enteritidis) were identified from 25 patients, with 1 isolate from blood and 24 from stool samples. The most common serovar was . Newport, isolated from 6 of the 25 patients, followed by . Breda (2 patients), . Eastbourne (2 patients), . Orion (2 patients) and 12 other serovars, each isolated from a single individual. These serovars displayed diverse antigenic profiles, grouped into 9 distinct serogroups. Antimicrobial resistance profiles and biofilm formation of the isolates were also assessed. Antimicrobial resistance was detected in three . Newport strains: two sequence type 31 (ST31) isolates carried the and resistance genes, while one ST166 isolate carried , , and . Biofilm formation varied among the serovars and was enhanced by cholesterol while inhibited by bile. Strong biofilm formation was observed in . Breda, . Hann, and . Eastbourne, whereas . Chicago and . Kentucky formed weak biofilms. This study highlights the diversity of NTS serovars circulating in Nairobi and emphasizes on the importance of localized studies in addressing regional variations in NTS epidemiology. To effectively mitigate the burden of NTS infections and curb the spread of AMR, sustained genomic surveillance, the development of advanced diagnostic tools for emerging infections, and the implementation of integrated public health interventions are essential.
非伤寒感染是一个重大的全球公共卫生问题，每年导致约1.5亿人患病和6万人死亡，大多数病例发生在低收入和中等收入国家。在本研究中，我们使用全基因组测序来鉴定和表征从肯尼亚内罗毕穆库鲁地区出现胃肠道症状的患者中分离出的罕见非伤寒血清型。从25名患者中鉴定出16种较不常见的非伤寒血清型（不包括鼠伤寒血清型和肠炎血清型），其中1株分离自血液，24株分离自粪便样本。最常见的血清型是纽波特血清型，从25名患者中的6名患者中分离得到，其次是布雷达血清型（2名患者）、伊斯特本血清型（2名患者）、猎户座血清型（2名患者）以及其他12种血清型，每种血清型仅从1名个体中分离得到。这些血清型呈现出多样的抗原谱，分为9个不同的血清群。我们还评估了分离株的抗菌药物耐药谱和生物膜形成情况。在3株纽波特菌株中检测到抗菌药物耐药性：2株序列型31（ST31）分离株携带blaCTX-M-15和blaTEM-1耐药基因，而1株ST166分离株携带blaCTX-M-15、blaTEM-1和blaCMY-2。生物膜形成在不同血清型之间存在差异，胆固醇可增强生物膜形成，而胆汁则抑制生物膜形成。在布雷达血清型、汉恩血清型和伊斯特本血清型中观察到强烈的生物膜形成，而芝加哥血清型和肯塔基血清型形成的生物膜较弱。本研究突出了在内罗毕流行的非伤寒血清型的多样性，并强调了开展本地化研究以应对非伤寒感染流行病学区域差异的重要性。为有效减轻非伤寒感染负担并遏制抗菌药物耐药性的传播，持续的基因组监测、开发针对新出现感染的先进诊断工具以及实施综合公共卫生干预措施至关重要。
