Nasopharyngeal carriage of Streptococcus pneumoniae in Gambian villagers.
BACKGROUND
To prepare for the introduction of a pneumococcal conjugate vaccine of restricted valency, we studied the nasopharyngeal carriage of Streptococcus pneumoniae in Gambian villagers.


METHODS
A cross-sectional survey was conducted in 21 villages after a census. We recorded demographic characteristics, information on medical history, and data on possible risk factors for carriage from subjects. We collected a nasopharyngeal swab specimen from each subject for isolation and serotyping of S. pneumoniae and for antibiotic susceptibility testing.


RESULTS
The prevalence of S. pneumoniae carriage among 2872 villagers was 72%. It was highest among infants (i.e., children aged <1 year; 97%); the rate was 93% among babies aged <1 month and decreased with increasing age (P<.001). Prevalence of carriage was linked to proximity to another village. Sixty-three percent of isolates recovered from children aged <5 years were covered by the 7-valent vaccine or were of a vaccine-related serotype, compared with 43% of isolates overall. Forty-three isolates (14.3%) tested were initially penicillin resistant; none had high-level resistance, and 4 had intermediate resistance. The rates of resistance to other antibiotics were as follows: trimethoprim-sulfamethoxazole, 39%; tetracycline, 32.3%; chloramphenicol, 6.3%; cefotaxime, 0.3%; and erythromycin, 0%. The rates were highest for isolates of vaccine serotypes.


CONCLUSIONS
Pneumococcal carriage rates among Gambian villagers are very high. A pneumococcal conjugate vaccine of restricted valency should reduce the pool of antibiotic-resistant pneumococci. The large reservoir of pneumococci of nonvaccine serotypes will require close monitoring when the vaccine is introduced.
Hill
Philip C
PC
Bacterial Diseases Programme, Medical Research Council Laboratories, Banjul, The Gambia. phill@mrc.gm
Akisanya
Abiodun
A
Sankareh
Kawsu
K
Cheung
Yin Bun
YB
Saaka
Mark
M
Lahai
George
G
Greenwood
Brian M
BM
Adegbola
Richard A
RA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002353:Carrier State; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D024881:Drug Resistance, Bacterial; D005260:Female; D005714:Gambia / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology*; D012307:Risk Factors; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents