Antimicrobial susceptibility and genetic characteristics of Propionibacterium acnes isolated from patients with acne.

BACKGROUND: Propionibacterium acnes is an important target in acne management. Antibiotic resistance has increased, reducing its clinical efficiency. OBJECTIVE: To study the prevalence, antimicrobial susceptibility patterns, and resistance mechanisms of P. acnes isolated from patients with acne. METHODS: Skin swabs were collected from 83 patients. Agar dilution determined the minimum inhibitory concentrations of five antibiotics. Polymerase chain reaction and DNA sequencing were used to identify mutations. Results P. acnes was isolated in 80 of 83 patients (96%), and 27 patients had resistance to antibiotics (33.7%). The mean age was older in the antibiotic-resistant group (20.8 ± 5.8 vs. 18.3 ± 3.7, P = 0.02). Resistance to trimethoprim-sulfamethoxazole was 26.3%, erythromycin 12.5%, and clindamycin 7.5%. All clindamycin-resistant strains had cross-resistance to erythromycin, and 40% erythromycin-resistant strains had cross-resistance to trimethoprim-sulfamethoxazole. All strains were sensitive to tetracycline and doxycycline. The use of topical erythromycin or clindamycin was a risk factor to carry resistant strains (P = 0.02, P = 0.04, respectively). Resistance to trimethoprim-sulfamethoxazole was associated with acne severity (P = 0.02). Six of the 10 erythromycin-resistant strains had a mutation in the peptidyl transferase region of the 23S rRNA gene: one A2058G and five A2059G. No strain carrying mutation G2057A was found. CONCLUSIONS: Resistance to trimethoprim-sulfamethoxazole was the most common pattern found, and further studies are required to clarify its resistance mechanism. A certain tetracycline resistance was expected, but interestingly all strains remained sensitive. Resistance to erythromycin and clindamycin were influenced using topical formulations. Mutation A2059G was related to high resistance to erythromycin. Antibiotic resistance is increasing, and new strategies are needed.

[Susceptibility to azoles and amphotericin B of isolates of Candida spp. Experience of a university health network, between 2004 and 2010]. / Susceptibilidad a azoles y anfotericina B de aislados de Candida spp. Experiencia de una red de salud universitaria,entre 2004 y 2010.

OBJECTIVE: To describe antifungal susceptibility testing surveillance (December 2004-September 2010) in Candida spp., for amphotericin B, fluconazole and voriconazole, at the Laboratorio de Microbiología, Pontificia Universidad Católica de Chile. METHOD: The study was performed utilizing E test and included yeasts from invasive origin and isolates in which antifungal susceptibility testing was asked for by the patient's physician. RESULTS: The yeasts were mainly recovered from urine samples (n: 64), blood cultures (n: 51) and secretions (n: 24). Two hundred ninety three isolates were studied: C. albicans (38%), C. glabrata (30%), C. tropicalis (11%), C. parapsilosis (10%), C. krusei (4%) and others (7%). All Candida species were 100% susceptible to amphotericin B, except C. krusei (1/12). Fluconazole's global susceptibility in C. albicans was 91.8%, but 100% in isolates from blood cultures versus 76% in isolates from urine. C. tropicalis was 93.9% susceptible to fluconazole, C. parapsilosis, 90% and C. glabrata 30.3%. C. krusei had no susceptible isolates to fluconazole. Voriconazole resistance was mainly present in C. glabrata (11.5%). CONCLUSIONS: We recommend the study of antifungal susceptibility in isolates from invasive origin, selected urine strains and C. glabrata. Fluconazole remains effective in C. albicans from blood.

Susceptibilidad a azoles y anfotericina B de aislados de Candida spp: Experiencia de una red de salud universitaria,entre 2004 y 2010 / Susceptibility to azoles and amphotericin B of isolates of Candida spp: Experience of a university health network, between 2004 and 2010

Objective: To describe antifungal susceptibility testing surveillance (December 2004-September 2010) in Candida spp., for amphotericin B, fluconazole and voriconazole, at the Laboratorio de Microbiología, Pontificia Universidad Católica de Chile. Method: The study was performed utilizing E test and included yeasts from invasive origin and isolates in which antifungal susceptibility testing was asked for by the patient's physician. Results: The yeasts were mainly recovered from urine samples (n: 64), blood cultures (n: 51) and secretions (n: 24). Two hundred ninety three isolates were studied: C. albicans (38%), C. glabrata (30%), C. tropicalis (11%), C. parapsilosis (10%), C. krusei (4%) and others (7%). All Candida species were 100% susceptible to amphotericin B, except C. krusei (1/12). Fluconazole's global susceptibility in C. albicans was 91.8%, but 100% in isolates from blood cultures versus 76% in isolates from urine. C. tropicalis was 93.9% susceptible to fluconazole, C. parapsilosis, 90% and C. glabrata 30.3%. C. krusei had no susceptible isolates to fluconazole. Voriconazole resistance was mainly present in C. glabrata (11.5%). Conclusions: We recommend the study of antifungal susceptibility in isolates from invasive origin, selected urine strains and C. glabrata. Fluconazole remains effective in C. albicans from blood.

Objetivo: Describir la susceptibilidad antifúngica in vitro (anfotericina B, fluconazol y voriconazol) de aislados de Candida spp., observada desde diciembre 2004 a septiembre 2010 en el Laboratorio de Microbiología de la Pontificia Universidad Católica de Chile. Material y Método: Se realizó estudio de susceptibilidad mediante E test® a todas las cepas invasoras y a aquellas en que se solicitara dirigidamente antifungigrama (aislados locales o derivados desde otros centros). Resultados: Se estudiaron 293 aislados, principalmente de muestras de orina (n: 64), hemocultivos (n: 51) y secreciones (n: 24). Las especies correspondieron a C. albicans (38%), C. glabrata (30%), C. tropicalis (11%), C. parapsilosis (10%), C. krusei (4%) y otras (7%). Hubo 100% de susceptibilidad a anfotericina B, excepto en C. krusei (1/12 resistente). La susceptibilidad a fluconazol fue: C. albicans 91,8% (100% en aislados de sangre vs 76% en orina); C. tropicalis, 93,9%, C. parapsilosis, 90% y C. glabrata 30,3%. Candida krusei, no tuvo aislados susceptibles a fluconazol. La resistencia a voriconazol se evidenció fundamentalmente en C. glabrata (11,5%). Conclusiones: Recomendamos realizar estudio de susceptibilidad en aislados de muestras invasoras, casos seleccionados de cepas de orina y ante sospecha de C. glabrata. Fluconazol mantiene efectividad en C. albicans proveniente de sangre.

[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.