Abstract
Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide. Rates of carriage are highest in infants and the elderly. The objectives of this study were to determine the rate of nasopharyngeal colonization by S. pneumoniae, and to describe the antibiotic resistant patterns and the serotypes of the carried isolates. A cross-sectional study design was used. Nasopharyngeal swabs were collected from 315 children in the months of October and November 2010 and processed to isolate S. pneumoniae. The isolates were serotyped by the Quellung reaction and their antibiotic susceptibilities assessed by the disc diffusion method. The overall nasopharyngeal carriage rate for S. pneumoniae was 17%. Seventeen serotypes were detected amongst 55 strains analysed: 6A, 23F, 19F, 13, 6B, 14A, 20, 7C, 1, 15B, 35B, 19A, 11A, 34, 5, 3 and 23A. Susceptibility testing revealed that nearly all (98%) were resistant to cotrimoxazole, 9% were resistant to penicillin and 7% to cefotaxime. Resistance to chloramphenicol and erythromycin was 2% and 4%, respectively. All isolates were fully sensitive to tetracycline.High levels of cotrimoxazole resistance and some resistance to other antimicrobial agents commonly used in Thika District Hospital shows that there is need to revise antimicrobial policy in this region in the treatment of invasive pneumococcal infections. The frequent serotypes found in this study have previously been associated with pneumococcal infections in children. Several of these serotypes are included in the ten-valent vaccine and therefore use of this vaccine will help reduce pneumococcal infections in Thika.
Highlights
Streptococcus pneumoniae is an inhabitant of the human upper respiratory tract.[1]
S. pneumoniae was isolated from the nasopharynx in 55 of the 315 children, representing a carriage rate of 17%
There was no significant difference in carriage rates between males and females
Summary
Streptococcus pneumoniae is an inhabitant of the human upper respiratory tract.[1] The main reservoir of S. pneumoniae is the human nasopharynx and this is the main source of person to person transmission.[1] Pneumococci are usually spread through respiratory secretions and aerosols and give rise to an invasive infection only after spreading to other areas of the respiratory tract, or, if they penetrate the nasopharyngeal mucosa, leading to systemic circulation via the cervical lymphatic.[2] Carriage rates differ depending on environment and age, with the highest carriage rates occurring in children between two and four years old.[3] The risk of disease is highest amongst children below five years old, older adults, smokers, and persons with certain chronic illnesses.[4] Children under five years old are frequently colonised for prolonged periods with the same serotypes.[5] Only a small percentage of colonised children develop an invasive infection, but pneumococcal nasopharyngeal isolates reflect the strains currently circulating in the community.[1] Treatment of pneumococcal infections is dependent on the site of infection and currently involves administration of antimicrobial agents and immunisations with the pneumococcal polysaccharides vaccines.[6] The most common agents currently being used by physicians to treat patients are the beta-lactam antibiotics which include penicillins, cephalosporins, monobactams and carbapenems.[7] Other antibiotics include the macrolides and fluoroquinolones.[8]
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