[Streptococcus agalactiae increase in resistance to erythromycin and clindamycin in vaginal-anal colonization in third quarter of pregnancy in one decade of universal screening]. / Aumento de resistencia de Streptococcus agalactiae vaginal-anal en el tercer trimestre de gestación a eritromicina y clindamicina al cabo de una década de tamizaje universal.

INTRODUCTION: Streptococcus agalactiae (GBS) is the main causative agent of early perinatal sepsis. The acquisition of prevention policies has led to frequent use of intrapartum antibiotics. Surveillance of antimicrobial resistance is indispensable for defining drugs of choice and alternatives for such prophylaxis. OBJECTIVES: To determine the evolution of antimicrobial resistance of GBS from maternal colonization to drugs used in the prevention of neonatal sepsis, between 2002 and 2008. METHODS: We studied 100 GBS positive vaginal and anal samples from pregnant women. Disc diffussion susceptibility method was performed for penicillin, ampicillin, cefazolin, erythromycin and clindamycin according to the Clinical and Laboratory Standards Institute (CLSI). RESULTS: We analyzed the susceptibility of 99 strains. Seventeen were resistant to erythromycin (17.1%) and 13 were resistant to clindamycin (13.1%). Thirteen of the 17 strains resistant to erythromycin had the MLS phenotype (resistance to erythromycin and clindamycin) and 4 had the M phenotype (resistance to erythromycin only). Within the MLS phenotype, resistance was constitutive in 9 strains, and induced in 4 strains (positive D test). Compared with 2002 there was a significant increase in resistance to clindamycin (from 3.27% to 13.1% p < 0.002) and erythromycin (1.09% to 17% p < 0.001). 100% GSB remained sensitive to penicillin and ampicillin. CONCLUSIONS: GBS remains highly susceptible to drugs of choice for prevention of perinatal sepsis. There is a significant increase in antimicrobial resistance to clindamycin and erythromycin. Therefore, it is necessary to request susceptibility testing in GBS from third trimester of pregnancy screening in patients allergic to penicillin.

Análisis de los fenotipos y genotipos de resistencia a eritromicina y clindamicina en cepas de Streptococcus pyogenes aisladas en Chile en un período de 10 años / Resistance phenotypes and genotypes of Streptococcus pyogenes clinical isolates in Chile over a 10-year period

Background: Macrolide and lincosamide resistance in Streptococcus pyogenes is due to the acquisition of mef, ermB and ermA genes, which confer different resistance phenotypes, namely M, MLSBconstitutive and MLSBinducible respectively. The last report of resistance in Chile was done in the period 1990-1998, in which resistance to macrolides was 5.4 percent, with M phenotype as the predominant one. Aim: To characterize the evolution of erythromycin and clindamycin resistance and their associated genes in S. pyogenes strains isolated from patients with invasive and non-invasive infections in the period 1996 to 2005. Material and Methods: Resistance to erythromycin and clindamycin was determined in 1,282 clinical isolates using the disk diffusion test. Resistant isolates were analyzed by polymerase chain reaction (PCR) for the presence of the above mentioned resistance genes. Results: Global resistance to erythromycin and clindamycin was 3.5 and 0.7 percent respectively. Eighty percent of the resistant strains possessed the M. phenotype. Conclusions: Resistance levels of S. pyogenes have decreased in Chile in the last years. Most resistant strains have M phenotype in contrast to many countries in which the MLSB constitutive phenotype is the predominant one.

[Resistance phenotypes and genotypes of Streptococcus pyogenes clinical isolates in Chile over a 10-year period]. / Análisis de los fenotipos y genotipos de resistencia a eritromicina y clindamicina en cepas de Streptococcus pyogenes aisladas en Chile en un período de 10 años.

BACKGROUND: Macrolide and lincosamide resistance in Streptococcus pyogenes is due to the acquisition of mef, ermB and ermA genes, which confer different resistance phenotypes, namely M, MLSBconstitutive and MLSBinducible respectively. The last report of resistance in Chile was done in the period 1990-1998, in which resistance to macrolides was 5.4%, with M phenotype as the predominant one. AIM: To characterize the evolution of erythromycin and clindamycin resistance and their associated genes in S. pyogenes strains isolated from patients with invasive and non-invasive infections in the period 1996 to 2005. MATERIAL AND METHODS: Resistance to erythromycin and clindamycin was determined in 1,282 clinical isolates using the disk diffusion test. Resistant isolates were analyzed by polymerase chain reaction (PCR) for the presence of the above mentioned resistance genes. RESULTS: Global resistance to erythromycin and clindamycin was 3.5 and 0.7% respectively. Eighty percent of the resistant strains possessed the M. phenotype. CONCLUSIONS: Resistance levels of S. pyogenes have decreased in Chile in the last years. Most resistant strains have M phenotype in contrast to many countries in which the MLSB constitutive phenotype is the predominant one.

Post-streptococcal acute glomerulonephritis in Chile--20 years of experience.

In order to characterize the epidemiological and clinical picture of post-streptococcal acute glomerulonephritis (PSAGN), a prospective study was designed to investigate all admissions to a general hospital of a local health service in Chile. The protocol included the investigation of previous streptococcal infections (SI), clinical symptoms and signs, socioeconomic situation (SES), throat and skin swabs for the isolation of group A beta-hemolytic streptococci, sequential determination of serum antistreptolysin O (ASO) titer, anti-DNAase B antibodies, and C3. During the 20 years studied, 926 cases were admitted (56% males). Incidence showed an endemic period (EP) 1980-1983, an epidemic outbreak (EO) 1984-1989, and a late period (LP) 1990-1999, with a rate per 100,000 inhabitants of 6.2, 13.2, and 1.7, respectively. The clinical picture was similar in the three periods. SES was homogeneous, with 80% of the population in low and middle-low categories. The average size of the family was 6.9 compared with 4.8 in the general population. Pyoderma was more frequent than pharyngeal infection, and more so during the EO. The isolation rate of group A beta-hemolytic streptococci from the pharynx was 20% compared with 60% from skin swabs. During EP, the most prevalent serotypes were T14-M0 and T1-M1 from the pharynx and TImp19-M0 from the skin. During EO, T14-M0 was more prevalent (30%). M or T classification was possible in EP and EO in 80%-85% of all strains isolated from the two locations. Significant titers for ASO and anti-DNAase B were found on admission: 55% and 75%, respectively. Both tests allowed identification of 100% of previous SI. In conclusion, the incidence of PSAGN had an uneven trend during the observed period. EO was mainly due to skin infection and a predominance of one serotype, T14-MO, was observed. After the EO, the yearly rate gradually decreased from 13.2 in 1988 to 0.0 in 1999, a rate similar to that of industrialized nations.