Genotyping of methicillin-resistant Staphylococcus aureus isolates obtained in the Northeast region of Brazil

Methicillin-resistant Staphylococcus aureus (MRSA) is a major agent of hospital infections worldwide. In Brazil, a multiresistant MRSA lineage (ST239-SCCmecIIIA), the so-called Brazilian epidemic clone (BEC), has predominated in all regions. However, an increase in nosocomial infections caused by non-multiresistant MRSA clones has recently been observed. In the present study, 45 clinical isolates of MRSA obtained from a university hospital located in Natal city, Brazil, were identified by standard laboratory methods and molecularly characterized using staphylococcal chromosome cassette mec (SCCmec) typing and pulsed-field gel electrophoresis. Antimicrobial susceptibility testing was carried out using CLSI methods. The MRSA isolates studied displayed a total of 8 different pulsed-field gel electrophoresis patterns (types A to H) with predominance (73 percent) of pattern A (BEC-related). However, MRSA harboring SCCmec type IV were also identified, 3 (7 percent) of which were genetically related to the pediatric clone - USA800 (ST5-SCCmecIV). In addition, we found a considerable genetic diversity within BEC isolates. MRSA displaying SCCmecIV are frequently susceptible to the majority of non-β-lactam antibiotics. However, emergence of multiresistant variants of USA800 was detected.

Genotyping of methicillin-resistant Staphylococcus aureus isolates obtained in the Northeast region of Brazil.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major agent of hospital infections worldwide. In Brazil, a multiresistant MRSA lineage (ST239-SCCmecIIIA), the so-called Brazilian epidemic clone (BEC), has predominated in all regions. However, an increase in nosocomial infections caused by non-multiresistant MRSA clones has recently been observed. In the present study, 45 clinical isolates of MRSA obtained from a university hospital located in Natal city, Brazil, were identified by standard laboratory methods and molecularly characterized using staphylococcal chromosome cassette mec (SCCmec) typing and pulsed-field gel electrophoresis. Antimicrobial susceptibility testing was carried out using CLSI methods. The MRSA isolates studied displayed a total of 8 different pulsed-field gel electrophoresis patterns (types A to H) with predominance (73%) of pattern A (BEC-related). However, MRSA harboring SCCmec type IV were also identified, 3 (7%) of which were genetically related to the pediatric clone--USA800 (ST5-SCCmecIV). In addition, we found a considerable genetic diversity within BEC isolates. MRSA displaying SCCmecIV are frequently susceptible to the majority of non-beta-lactam antibiotics. However, emergence of multiresistant variants of USA800 was detected.

Multicenter prospective surveillance of oral Candida dubliniensis among adult Brazilian human immunodeficiency virus-positive and AIDS patients.

The incidence of C. dubliniensis in South America has not yet been determined. In the present study, oral swab samples were taken from 108 HIV-infected/AIDS individuals attending 6 separate Brazilian HIV-treatment centers to determine the incidence of C. dubliniensis in this population. Swabs were plated onto CHROMagar Candida medium and 155 isolates, presumptively identified as C. albicans or C. dubliniensis were further investigated. In a preliminary screen for C. dubliniensis, 13 of the 155 isolates showed no or poor growth at 42 degrees C, and all them were subjected to randomly amplified polymorphic DNA (RAPD) and polymerase chain reaction (PCR) analysis using C. dubliniensis-specific primers. We confirmed that 4 out of 13 isolates were C. dubliniensis, representing an incidence rate of 2.8% for the Brazilian HIV-infected population infected with yeasts exhibiting green colonies on CHROMagar Candida. This value is significantly lower than those reported in Ireland and the United States.

Oral colonization by Candida spp. among AIDS household contacts.

This study was designed to investigate the oral yeast colonization rate of household contacts of AIDS patients. Sixty-four AIDS household contacts were sequentially enrolled along with 103 HIV-negative blood bank donors (control group). Samples were obtained by swabbing the oral mucosa. Yeast isolates were identified by classical methods and antifungal susceptibility testing was performed according to NCCLS microbroth assay. Candida spp. was recovered from the oral cavity of 33% of the AIDS household contacts, in contrast with 14% of the control group (P = 0.003 or P = 0.04 after adjusting for oral prosthesis use). Candida albicans was the most frequently isolated species in both groups. All of the isolates were susceptible to fluconazole, itraconazole and ketoconazole. In conclusion, we were able to demonstrate a higher colonization rate in the AIDS household contacts group compared with the control group. No resistant isolates to antifungal drugs was observed. We suggest that the contact with AIDS patients may play a role as a risk factor for developing oral colonization by Candida spp.

First isolation of Candida dubliniensis in Rio Grande do Sul, Brazil.

Candida dubliniensis is a newly recognized species closely phylogenetically related to Candida albicans and is commonly associated with oral candidiasis in human immunodeficiency virus-positive patients. In this paper we report the isolation of three strains of C. dubliniensis, from AIDS patients, in the state of Rio Grande do Sul (Brazil). The phenotypic identification was based on germ tube emission, abundant production of chlamydospores, assimilation of sucrose but not of xylose and the inability to grow at 42 degrees C. Randomly amplified polymorphic DNA (RAPD) analysis and genomic DNA sequencing confirmed the distinct genetic nature C. dubliniensis. Topics related to the epidemiology, isolation, phenotypical and genotypical identification of C. dubliniensis are also discussed.

Azole resistance among oral Candida species isolates from AIDS patients under ketoconazole exposure.

This is a prospective study designed to investigate species distribution and azole susceptibility profile among Candida spp. isolated from the oral cavities of AIDS patients. One hundred thirty-two AIDS patients sequentially admitted at a teaching tertiary care hospital were enrolled in this study. Samples were obtained by swabbing the oral cavities of the patients. Yeast isolates were identified by classical methods and the antifungal susceptibility profile was further determined according to the NCCLS microbroth assay. Among all patients with prescriptions of systemic antifungal drugs, ketoconazole had been elected to treat 56% of patients. We found 82% of oral yeast carriage, 22% of them harboring non-albicans species. Overall rates of susceptibility dose dependent/resistance to azoles was 16% for itraconazole, 13% for ketoconazole, and 10% for fluconazole with a high agreement rate among the susceptibility profiles of all isolates tested against the triazoles.

Evaluation of the AUXACOLOR system for the identification of clinical yeast isolates.

In the last decade the number of systemic yeast infections has increased significantly. Although Candida albicans is the most frequently isolated yeast from clinical specimens, the emergence of non-albicans species has clearly been a recent concern. As a consequence, there is a greater need for rapid and accurate methods for yeast identification. The aim of this study was to evaluate the performance of the AUXACOLOR system (Sanofi Diagnostics Pasteur) for the identification of clinically relevant yeasts, as compared with the conventional method. Yeast isolates (n = 97) belonging to 12 species were identified by the commercial system and the classic method. Correct identifications were obtained by using AUXACOLOR system in 79.4% of the isolates tested. Misidentification occurred in 5.2% of the strains and 15.5% were not identified due to a failure in the manufacturer's data base. In order to improve its accuracy, there is a need for expanding the database or revamping the tests included in the system.

Treatment of kala-azar in Brazil with Amphocil (amphotericin B cholesterol dispersion) for 5 days.

We have treated 10 patients suffering from kala-azar in Brazil with Amphocil (amphotericin B cholesterol dispersion) at a dose of 2 mg/kg/d for 5 d, following an earlier study in which this dosage for 7 d was found to cure all of 9 patients, with no relapse during 12 months. In the present study, all patients demonstrated initial resolution of disease. Parasites were absent upon bone marrow re-aspiration 2 weeks after therapy; no spleen extended beyond the costal margin 2 months after therapy; white blood cell counts, platelet counts, and serum levels of albumin rapidly returned to normal. Although one patient relapsed at 5 months, 8 of the other 9 patients had spleens of normal size (undetectable on deep palpation) at 12 months after therapy. Fever, sometimes accompanied by increased respiratory rate, occurred on the first day of drug infusion in 8 of 10 patients and was more severe in patients < 6 years old. Pre-medication with a non-steroidal anti-inflammatory agent (diclofenac potassium) before the next 4 infusions protected against this side effect in 5 of 6 patients. The results of this and our previous study suggest that the most appropriate regimen of Amphocil for kala-azar is 2 mg/kg/d for 7 d, with pre-medication each day, in patients aged > 5 years.

Treatment of Brazilian kala-azar with a short course of amphocil (amphotericin B cholesterol dispersion).

Amphotericin B is an effective but toxic antileishmanial agent. Lipid-encapsulated amphotericin B should have a high therapeutic index for visceral leishmaniasis because reticuloendothelial cells, the sole site in which Leishmania is found, will phagocytize and concentrate the complex. Amphotericin B cholesterol dispersion (Amphocil; 2 mg/[kg.d] intravenously) was administered to 10 Brazilians with kala-azar for 10 days (cohort 1) and to 10 Brazilians with kala-azar for 7 days (cohort 2). All patients were successfully treated: 19 of the 20 patients were without visible parasites in the bone marrow; the mean time to afebrility was 4.2 days; spleen size regressed by a mean of 79% 2 months after therapy; and no patient had clinical or laboratory abnormalities by the end of 6-12 months of follow-up. Side effects were fever and chills accompanied by respiratory distress, but not nephrotoxicity, in children < 3 years of age.