Paul J
Brighton Public Health Laboratory, Royal Sussex County Hospital, UK.
Trans R Soc Trop Med Hyg. 1997 Nov-Dec;91(6):632-7. doi: 10.1016/s0035-9203(97)90500-9.
By the 1930s several studies had shown that Streptococcus pneumoniae was an important pathogen in Nairobi (Kenya) and various risk factors for infection were recognized, including seasonally cold conditions, overcrowding and recent arrival in the city. Research into pneumococcal disease declined with the arrival of penicillin but recently interest has been rekindled by recognition of the pneumococcus as a human immunodeficiency virus (HIV)-associated pathogen and by the emergence of antibiotic resistance. The pneumococcus and its association with HIV were studied during the course of the Wellcome Trust/Kenya Medical Research Institute HIV Programme in Nairobi (1988-1993). There were generally high rates of pneumococcal disease. The pneumococcus (with tuberculosis and salmonellosis) was a major HIV-related pathogen. One study showed HIV seropositivity to confer a relative risk of 17.8 for pneumococcal infection. Recurrent infection accounted for a large proportion (25%) of disease episodes in a longitudinally studied cohort of HIV patients. There were higher pneumococcal carriage rates in HIV-positive than in HIV-negative patients (28% vs. 16%, P = 0.003). High rates of resistance were found to penicillin (25%). Molecular characterization of penicillin-resistant strains identified 11 separate clones, showing great genetic diversity in a small sample of isolates, and there was evidence of horizontal spread of penicillin-binding protein genes between separate lineages. Molecular characterization of isolates from patients with recurrent disease suggested that both relapse and reinfection might occur. There was molecular evidence of transfer of capsular genes between clones (serotype switching). The overall spectrum of serotypes resembled those reported elsewhere, most serotypes being included in the 23-valent vaccine. Higher numbered serotypes were associated with respiratory tract source and antibiotic resistance. Various methods were used to show 82% concordance between pernasal and blood isolates in pneumonia cases. HIV-seropositive patients were more prone to infection with penicillin- and tetracycline-resistant organisms than seronegative patients (penicillin, 27% vs. 7%; tetracycline, 40% vs. 17%), a difference reflected by different serotype profiles in the 2 groups. These studies highlight the importance of the pneumococcus as an HIV-related pathogen in one part of Africa. The high rates of antibiotic resistance are a cause of concern. There should be continued monitoring of resistance patterns, and assessments of the significance of pneumococcal disease made elsewhere in Africa are to be encouraged.
到20世纪30年代，多项研究表明肺炎链球菌是内罗毕（肯尼亚）的一种重要病原体，并且人们认识到了多种感染风险因素，包括季节性寒冷天气、过度拥挤以及近期刚抵达该市。随着青霉素的出现，对肺炎球菌疾病的研究有所减少，但最近，由于认识到肺炎球菌是一种与人类免疫缺陷病毒（HIV）相关的病原体以及抗生素耐药性的出现，人们对其的兴趣再度燃起。在韦尔科姆基金会/肯尼亚医学研究所于内罗毕开展的HIV项目（1988 - 1993年）过程中，对肺炎球菌及其与HIV的关联进行了研究。肺炎球菌疾病的发病率总体较高。肺炎球菌（与结核病和沙门氏菌病一起）是一种主要的与HIV相关的病原体。一项研究表明，HIV血清阳性使肺炎球菌感染的相对风险达到17.8。在一组接受纵向研究的HIV患者中，复发性感染占疾病发作的很大比例（25%）。HIV阳性患者的肺炎球菌携带率高于HIV阴性患者（28%对16%，P = 0.003）。发现对青霉素的耐药率很高（25%）。对耐青霉素菌株的分子特征分析鉴定出11个不同的克隆，在一小批分离株中显示出很大的遗传多样性，并且有证据表明青霉素结合蛋白基因在不同谱系之间水平传播。对复发性疾病患者分离株的分子特征分析表明，复发和再感染都可能发生。有分子证据表明克隆之间存在荚膜基因转移（血清型转换）。血清型的总体谱与其他地方报道的相似，大多数血清型包含在23价疫苗中。编号较高的血清型与呼吸道来源和抗生素耐药性相关。采用各种方法显示，在肺炎病例中，经鼻分离株与血液分离株的一致性为82%。HIV血清阳性患者比血清阴性患者更容易感染对青霉素和四环素耐药的病原体（青霉素，27%对7%；四环素，40%对17%），两组不同的血清型谱反映了这种差异。这些研究凸显了肺炎球菌作为非洲某一地区与HIV相关病原体的重要性。抗生素耐药率高令人担忧。应持续监测耐药模式，并鼓励对非洲其他地区肺炎球菌疾病的重要性进行评估。
