Contribution and resistance to macrolides S. pyogenes

The objective of the study carried out in Finland in 1997-2000 was to study separately the relationship between the consumption of all macrolides and azithromycin and the local level of resistance to macrolides in β-hemolytic group A streptococcus ( BHCA, S.pyogenes)

Azithromycin accounts for a third of the total amount of macrolides consumed in Finland. A relative disadvantage of the drug is considered to be a theoretically increased risk of developing resistance due to the long half-life and the sufficiently long maintenance of the sub-inhibitory concentrations of the drug in the body.

As part of the study, a comparison was made of the prevalence of BSA strains resistant to erythromycin and local data on the consumption of all macrolides and separately from azithromycin. For the period from 1997 to 2001 in all Finnish laboratories, the sensitivity to erythromycin of 50,875 strains of BSA was determined.

The prevalence of resistant strains was 9.2% in 1997, 17.1% in 1998, 11.3% in 1999, 8.1% in 2000 and 7.4% in 2001 For the period from 1995 to 2000 the frequency of the annual consumption of macrolides ranged from 1.15 to 2.85 per 1,000 population per day, while for azithromycin the rate was 0.302-1.22 per 1,000 population per day. The local level of resistance to erythromycin for one year was compared with local data on antibiotic consumption in the past year and with average consumption in the past 2 years. It turned out that there is a statistically significant relationship between the intake of macrolides and local resistance to erythromycin. No dependence on the level of resistance to consumption of azithromycin was detected.