Antimicrobial resistance in respiratory pathogens isolated in Brazil during 1999-2000

• Main Authors: Critchley Ian A., Blosser Renée S., Karlowsky James A., Yamakita Juri, Barth Alfonso, Sader Helio S., Mendes Caio, Teixeira Lucia, Rossi Flavia, Dias Cicero A. C., Jones Mark E., Thornsberry Clyde, Sahm Daniel F.
• Format: Article
• Language: English
• Published: Elsevier 2001-01-01
• Series: Brazilian Journal of Infectious Diseases
• Subjects: Streptococcus pneumoniae; antimicrobial resistance; surveillance study; respiratory pathogen
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-86702001000600002

The in vitro antimicrobial susceptibility of the respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis to commonly tested and prescribed agents was investigated during 1999-2000 and compared with results obtained during a previous 1997-1998 study. Of 448 isolates of S. pneumoniae collected and tested in 1999-2000, 77.2% were susceptible, 19.9% were intermediate, and 2.9% were resistant to penicillin, demonstrating that there were no major changes in susceptibility to penicillin from 1997-1998 (77.1% susceptible, 18.7% intermediate, 4.2% resistant). All S. pneumoniae isolates from 1999-2000 were susceptible to levofloxacin and vancomycin, and >90% were susceptible to the beta-lactams (amoxicillin-clavulanate, ceftriaxone, and cefuroxime) and macrolides (azithromycin and clarithromycin), showing that susceptibility to these agents also remained unchanged since 1997-1998. The most notable increase in resistance between the two studies was demonstrated by trimethoprim-sulfamethoxazole, which increased from 23.4% to 38.6%. Penicillin resistance correlated with resistance to beta-lactams, macrolides, and trimethoprim-sulfamethoxazole in both studies. In H. influenzae, the prevalence of beta-lactamase-producing isolates remained unchanged (10.6% in 1999-2000; 11.0% in 1997-1998). All H. influenzae isolates were susceptible to levofloxacin, ceftriaxone, cefuroxime, and azithromycin, and showed no change between the two studies. Trimethoprim-sulfamethoxazole resistance was present in 40.1% of isolates in 1999-2000, and in 45.2% in 1997-1998. In M. catarrhalis, the prevalence of beta-lactamase-producing isolates was unchanged (97.9% in 1999-2000; 98.0% in 1997-1998). The most active agents against M. catarrhalis were azithromycin (MIC90, <0.03 mug/ml) and levofloxacin (MIC90, 0.03 mug/ml). Overall, these results suggest that, in Brazil, between 1999-2000 and 1997-1998, there have been no significant changes in the susceptibility of respiratory pathogens to any of the commonly tested and prescribed agents with the exception of trimethoprim-sulfamethoxazole for S. pneumoniae.