As part of the continuing national antimicrobial surveillance, the national antimicrobial resistance
surveillance thailand (NARST), data of all clinical isolates of Streptococcus pneumoniae were collected from
28 hospitals in Thailand from 2000 to 2005. Epidemiological and microbiological data were obtained and
analyzed using the WHONET software program. Among all isolates tested for antimicrobial susceptibility, the
rates of penicillin resistance were constantly high, ranging from 42.4% in 2000 to 47.7% in 2005. The thirdgeneration
cephalosporin resistance rate, determined by Epsilon test (E-test) in 10% to 15% of all isolates
each year, ranged from 2.1% to 8.4%. The rates of erythromycin resistance ranged from 24.2% to 30.3%.
Surprisingly, one isolate in 2005 was resistant to levofloxacin. The rates of multi-drug resistance ranged from
14.8% to 34.3%.

In conclusion, the present (NARST) study documents remarkable increase of penicillin, erythromycin,
and multi-drug resistance rates in Thailand, especially among isolates from the North, the Center, the
East, and Bangkok; from university hospitals; from young children; and from non-sterile specimens.

Keywords: Anti-infective agents, Drug resistance, Bacterial, Epidemiology, Microbial sensitivity tests,
Population surveillance, Prevalence, Streptococcus pneumoniae, Thailand