Streptococcus pyogenesCollected in Torino (Northwest Italy) Between 1983 and 1998: Survey of Macrolide Resistance and Trend of Genotype by RAPD

Abstract

We surveyed macrolide resistance in 1,086 isolates of Streptococcus pyogenes, collected between 1983 and 1998, from throat swabs of children with untreated pharyngotonsillitis living in Torino (northwest Italy). In 1983 and 1985, the frequency of erythromycin resistance was 10%, and from 1990 to 1992 it was 4%. However, it rose to 16.6% in 1994 and reached 51% in 1996 before decreasing to 38.5% in 1998. Characterization of the phenotype of resistant isolates revealed the prevalence of constitutive resistance (CR) in 1996, whereas the M phenotype, characterized by resistance to 14- and 15-membered macrolides with susceptibility to clindamycin and streptogramin B, prevailed in 1998. Moreover, in 1997 we observed an increase in the frequency of autoagglutinating bacteria and, in 1998, of OF-negative S. pyogenes. Meanwhile, penicillin tolerance, assessed in the isolates collected from 1990 to 1996, decreased and disappeared. Random amplification of polymorphic DNA (RAPD) was used to obtain the genomic profile of 32 S. pyogenes strains. Four main DNA profiles were demonstrated, generally related to the macrolide-resistance phenotype and for the major part to the T serotype. These results indicate that RAPD is reliable as a first screening method in the epidemiological characterization of resistant S. pyogenes.

Erythromycin-Resistant Pharyngeal Isolates of Streptococcus pyogenes Recovered in Italy

“…Thus, a total of 127 macrolide-resistant isolates (Table 2) were found among 355 isolates. This resistance frequency (35.7%) is consistent with previous results in Italy (1,2,9,10,32).…”

Tetracycline and Macrolide Co-Resistance in Streptococcus pyogenes: Co-Selection As a Reason for Increase in Macrolide-Resistant S. pyogenes?

“…But it seems likely that the mef(A) gene has an advantage to the erm genes, at least in areas with high macrolide use, since Taiwan, Italy, and Spainall high-use countries-have experienced an increase in the proportion of mef(A) in MRSP. 2,3,14 Tetracycline resistance was found in 14% of S. pyogenes isolated from blood or spinal fluid (no MRSP) and in 52% of MRSP. 28 MRSP isolates.…”

Erythromycin-Resistant Group A Streptococci in Schoolchildren in Pittsburgh

“…[20][21][22] In a recent survey of 301 isolates from 24 states and the District of Columbia, all were sensitive to penicillin, ceftriaxone, and clindamycin, and only 2.6 percent were resistant to erythromycin and azithromycin. 21 However, many other countries, including Japan, 23 Korea, 24 Spain, 25,26 Italy, 27,28 Finland, 29,30 and Greece, 31 have a high prevalence of isolates that are resistant to erythromycin and other macrolide antibiotics. In Finland, the rates of erythromycin resistance among group A streptococci prompted an intense effort to decrease the use of macrolide antibiotics, which in turn led to a dramatic reduction in the prevalence of erythromycinresistant strains.…”