The aim of this study was to determine the evolution of resistance to macrolides and other antibiotics in strains of Streptococcus pyogenes isolated in the province of Gipuzkoa, Spain. During the period 1984-1996, all 2561 strains of Streptococcus pyogenes studied showed full susceptibility to penicillin. Until 1990, only 1.2% of Streptococcus pyogenes isolates were resistant to erythromycin. Since then, resistance to erythromycin increased every year until 1995, when 34.8% (87/250) of Streptococcus pyogenes strains were found to be resistant. In 1996 the rate of resistance to erythromycin was 17.8% (75/422). During the study period, 96.1% (246/256) of the Streptococcus pyogenes isolates resistant to erythromycin were susceptible to clindamycin. Of the remaining erythromycin-resistant Streptococcus pyogenes strains, resistance to clindamycin was constitutive in seven strains and inducible in three. When investigated by the polymerase chain reaction (PCR), all Streptococcus pyogenes strains resistant to erythromycin and susceptible to clindamycin showed the 1.4 kb fragment of the mefA gene, recently described as the novel macrolide-efflux-resistance determinant. The most frequent T-agglutination patterns among Streptococcus pyogenes resistant to erythromycin were T4 and T8,25. The emergence and rapid spread of erythromycin-resistant Streptococcus pyogenes in Gipuzkoa and its relationship to the presence of the mefA gene are described.

In a ten-year survey (1983-1992) of quinolone resistance in Escherichia coli causing urinary tract infections in a general practice patient population, 9,934 strains were tested. Resistance increased remarkably from 1989 onwards. The rate of resistance to pipemidic acid was < or = 6% before 1989 and 18% in 1992; the rate of resistance to ciprofloxacin (MIC > or = 4 mg/l) was 0.8% in 1989 and 7.1% in 1992. Although the consumption of older quinolones decreased the total consumption of quinolones increased yearly.

The prevalence of hepatitis A virus antibodies was studied using a commercial ELISA method. 2,214 subjects were included, 1,211 in 1992 and 1,003 during 1986-87. In 1992 the seroprevalence rates among subjects 1-9, 10-19, 20-29 and 30-39 years old were 2.4%, 21%, 57.6% and 87.5% respectively, as compared with 7.7%, 37.9%, 80.6% and 98.1% respectively, in a similar group of subjects studied 5 years earlier (p < or = 0.001). The reported number viral hepatitis cases declined from 35.0 per 100,000 people in 1984 to 8.9 per 100,000 in 1992. Concurrently, the age when contracting the disease rose. The mean age for patients acquiring hepatitis A was 15.5 in 1986-88 and 20.1 in 1991-92. The decline in incidence and prevalence of HAV infection indicates a progressive and continuous decrease in HAV circulation in this geographical area.

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