The role of the Xpert MTB/RIF assay among adolescents suspected of pulmonary tuberculosis in Rio de Janeiro, Brazil

Abstract INTRODUCTION The teste rápido molecular para tuberculose (TRM-TB) was introduced in 2014 in Brazil for tuberculosis screening. However, its role in adolescents in Brazil has not been studied. METHODS A descriptive study of adolescents with suspected tuberculosis using National Laboratory software. RESULTS Of 852 (15.4%) suspected cases, 131 were positive by TRM-TB and 2% were resistant to rifampicin. Among TRM-TB-positive cases, 105 (91.4%) were culture-positive. Sixty-four of 96 samples were sensitive to rifampicin by TRM-TB; 11 were resistant to other drugs by drug sensitivity test (DST). CONCLUSIONS Among suspected cases, 16% were diagnosed by TRM-TB, of which 17% were drug-resistant by DST.

Evaluation of the commercial kit SIRE nitratase for detecting resistant mycobacterium tuberculosis in Brazil

Abstract INTRODUCTION: This study aimed to evaluate a new commercial kit, Kit SIRE Nitratase-PlastLabor, for testing the drug susceptibility of clinical Mycobacterium tuberculosis isolates. METHODS: The accuracy of the Kit SIRE Nitratase was evaluated by examining the susceptibility (streptomycin, isoniazid, rifampicin, and ethambutol) of 40 M. tuberculosis isolates, using the proportion method with Lowenstein-Jensen medium or the BACTEC MGIT 960 system. RESULTS: The detection accuracy for streptomycin, isoniazid, rifampicin, and ethambutol was 95%, 97.5%, 100%, and 80%, respectively. CONCLUSIONS: The exceptional accuracy demonstrated by Kit SIRE Nitratase for isoniazid and rifampicin makes the kit an attractive option for screening M. tuberculosis strain resistance.

Evaluation of crystal violet decolorization assay for minimal inhibitory concentration detection of primary antituberculosis drugs against Mycobacterium tuberculosis isolates

In this study we evaluated the crystal violet decolorization assay (CVDA) for detection of minimum inhibitory concentration (MIC) of antituberculosis drugs. 53 isolates were tested in this study and 13 of them were multidrug resistant (MDR) isolates. The antibiotics concentrations were 2-0.06 mg/L for isoniazid (INH) and rifampicin (RIF) and were 16-0.25 mg/L for streptomycin (STM) and ethambutol (EMB). Crystal violet (CV-25 mg/L) was added into the microwells on the seventh day of incubation and incubation was continued until decolorization. Decolorization of CV was the predictor of bacterial growth. Overall agreements for four drugs were detected as 98.1%, and the average time was detected as 9.5 ± 0.89 day after inoculation. One isolate for INH and two isolates for STM were determined resistant in the reference method, but susceptible by the CVDA. One isolate was susceptible to EMB by the reference method, but resistant by the CVDA. All results were concordant for RIF. This study shows that CVDA is a rapid, reliable and suitable for determination of MIC values of Mycobacterium tuberculosis. And it can be used easily especially in countries with limited-sources.

Volatile compounds of Lamiaceae exhibit a synergistic antibacterial activity with streptomycin

Bacterial infections cause thousands of deaths in the world every year. In most cases, infections are more serious because the patient is already weakened, and often, the bacteria are already resistant to the antibiotics used. Counterparting this negative scenario, the interest in medicinal plants as an alternative to the synthetic antimicrobial drugs is blossoming worldwide. In the present work, we identified the volatile compounds of ethanol extracts of Melissa officinalis, Mentha sp., Ocimum basilicum, Plectranthus barbatus, and Rosmarinus officinalis by gas chromatography/mass spectrometry (GC/MS). Also was evaluated antimicrobial activity of ethanol extracts against 6 bacteria of clinical interest, and was tested the interaction of these extracts with a commercial antibiotic streptomycin. Phytol was a compound identified in all extracts by GC/MS, being majoritary component in Plectranthus barbatus and Rosmarinus officinalis. The Gram-positive bacteria were more sensitive to ethanol extracts, and Plectranthus barbatus and Rosmarinus officinalis were the most active extracts. Ethanol extracts exhibited a synergetic effect with streptomycin. These results encourage additional studies, in order to evaluate the possibilities of using ethanol extracts of Lamiaceae family as natural source for antibacterial activity.

Impairing methylations at ribosome RNA, a point mutation-dependent strategy for aminoglycoside resistance: The rsmG case / Mutaciones en genes modificadores de ARN ribosómico y la resistencia a aminoglucósidos: el caso del gen rsmG

Introduction: Aminoglycosides like streptomycin are well-known for binding at specific regions of ribosome RNA and then acting as translation inhibitors. Nowadays, several pathogens have been detected to acquire an undefined strategy involving mutation at non structural ribosome genes like those acting as RNA methylases. rsmG is one of those genes which encodes an AdoMet-dependent methyltransferase responsible for the synthesis of m 7 G527 in the 530 loop of bacterial 16S rRNA. This loop is universally conserved, plays a key role in ribosomal accuracy, and is a target for streptomycin binding. Loss of the m 7 G527 modification confers low-level streptomycin resistance and may affect ribosomal functioning. Objectives: After taking into account genetic information indicating that some clinical isolates of human pathogens show streptomycin resistance associated with mutations at rsmG , we decided to explore new hot spots for mutation capable of impairing the RsmG in vivo function and of promoting low-level streptomycin resistance. Materials and methods: To gain insights into the molecular and genetic mechanism of acquiring this aminoglycoside resistance phenotype and the emergence of high-level streptomycin resistance in rsmG mutants, we mutated Escherichia coli rsmG and also performed a genotyping study on rpsL from several isolates showing the ability to grow at higher streptomycin concentrations than parental strains. Results: We found that the mutations at rpsL were preferentially present in these mutants, and we observed a clear synergy between rsmG and rpsL genes to induce streptomycin resistance. Conclusion: We contribute to understand a common mechanism that is probably transferable to other ribosome RNA methylase genes responsible for modifications at central sites for ribosome function.

Introducción. Los aminoglucósidos son moléculas antibióticas capaces de inhibir la síntesis de proteínas bacterianas tras su unión al ribosoma procariota. La resistencia a aminoglucósidos está clásicamente asociada a mutaciones en genes estructurales del ribosoma bacteriano; sin embargo, varios estudios recientes han demostrado, de forma recurrente, la presencia de un nuevo mecanismo dependiente de mutación que no involucra genes estructurales. El gen rsmG es uno de ellos y se caracteriza por codificar una metiltransferasa que sintetiza el nucleósido m 7 G527 localizado en el loop 530 del ribosoma bacteriano, este último caracterizado como sitio preferencial al cual se une la estreptomicina. Objetivo. Partiendo de las recientes asociaciones clínicas entre las mutaciones en el gen rsmG y la resistencia a estreptomicina, este estudio se propuso la caracterización de nuevos puntos calientes de mutación en este gen que puedan causar resistencia a estreptomicina usando Escherichia coli como modelo de estudio. Materiales y métodos. Se indagó sobre el mecanismo genético y molecular por el cual se adquiere la resistencia a estreptomicina y su transición a la resistencia a altas dosis mediante mutagénesis dirigida del gen rsmG y genotipificación del gen rpsL . Resultados. Se encontró que la mutación N39A en rsmG inactiva la proteína y se reportó un nuevo conjunto de mutaciones en rpsL que confieren resistencia a altas dosis de estreptomicina. Conclusiones. Aunque los mecanismos genéticos subyacentes permanecen sin esclarecer, se concluyó que dichos patrones secuenciales de mutación podrían tener lugar en otros genes modificadores del ARN bacteriano debido a la conservación evolutiva y al papel crítico que juegan tales modificaciones en la síntesis de proteínas.

Susceptibilidad de M. tuberculosis a drogas antituberculosas, determinada por dos técnicas, en el estado Sucre, Venezuela / usceptibility of M. tuberculosis to antituberculosis drugs as determined by two methods, in Sucre state, Venezuela

El objetivo de este trabajo fue evaluar la resistencia a isoniacida (INH), rifampicina (RIF), estreptomicina (STR) y etambutol (EMB) de 59 cepas de Mycobacterium tuberculosis, aisladas en el período agosto 2005-diciembre 2006, en el estado Sucre, Venezuela, empleando el método de proporciones de Canetti y de nitrato reductasa. Se encontró 6,3% de resistencia primaria y 14,3% de adquirida. Una cepa fue considerada MDR, al presentar resistencia a RIF e INH. Se comparó la prueba de nitrato reductasa con el método de las proporciones, encontrándose 100% de concordancia entre los resultados de los dos métodos para INH, RIF y EMB, y 95,65% para STR. Además, la prueba nitrato reductasa produjo resultados en 10 a 14 días, comparado con 42 días para el método de proporciones, por lo que la primera se postula como una alternativa muy valiosa para acortar el tiempo de respuesta en la valoración de la susceptibilidad de M. tuberculosis. La secuencia del gen rpoB en la cepa resistente a RIF demostró la presencia de una mutación no descrita anteriormente en la región hipervariable de 81 pares de bases, donde se ha reportado el mayor número de mutaciones de cepas resistentes a RIF. Esta mutación produjo un cambio en el codón 456 de TCG > CAG. Al comparar nuestros resultados con los hallados en el último estudio de prevalencia de resistencia realizado en el estado, se demuestra una disminución en la circulación de cepas resistentes en la zona de estudio.

The objective of this study was to evaluate the resistance to isoniazid (INH), rifampicin (RIF), streptomycin (STR) and ethambutol (EMB), with the Canetti’s proportions method (PM) and the nitrate reductase assay (NRA) of 59 clinical strains of Mycobacterium tuberculosis, isolated in the period of august 2005 to december 2006, in Sucre state, Venezuela. Primary and acquired drug resistance was 6.3% and 14.3%, respectively. Only one strain was found to be multidrug resistant (MDR). The overall agreement between the NRA and PM was 100% for INH, RIF and EMB, and 96% for STR. The time to obtain results was 10 to 14 days for the NRA, compared to 42 days for the PM. The NRA was easy to perform and therefore represents a useful tool for rapid and accurate determination of drug-resistant M. tuberculosis. The sequence of the rpoB gene of the RIF resistant strain demonstrated a never described mutation (change in the codon 456; TCG > CAG) in the hypervariable region of 81 base pairs where most of the mutations of the RIF resistant strains have been reported. Comparison of our results with those of the last resistance prevalence study carried out in the years 1998-1999, shows a decrease in the studied area.

Biomasa fúngica y bacteriana como indicadoras del secuestro de C en suelos de sabanas sustituidos por pinares en Uverito, Venezuela

Fungal and bacterial biomass as indicators of soil C sequestration in savannas soils substituted by pine plantations. A transformation of any natural ecosystem to an agricultural or forest system leads to an important soil modification, not only in the total carbon pool, but also in the carbon associated to the microbial biomass. This way, carbon quantification on soil quality is important for the determination of impacts of agricultural practices and land use changes. The aim of this study was to the determine, through the selective inhibition technique, the fungal and bacterial biomass, and fungal-to-bacterial ratio (F:B) in pine plantations (Pinus caribaea var. hondurensis), to establish if these parameters are sensible indicators of changes in the carbon content in Uverito soils (Venezuela). Furthermore, the inhibitor additivity ratio (IAR) and total combined inhibition (TCI) were carried out to determine if the antibiotics caused non-target inhibition. The quantification of fungal and bacterial biomass was carried out by using of cyloheximide as fungal inhibitor, and streptomycin and chloranphenicol as specific bacterial inhibitors. This research evidences that this land use change exerted a significant effect on soil microbial biomass, and shows that in pine plantations there is a dominance of the fungal component, in contrast to the native savanna, in which the bacterial biomass dominates. The substitution of native savanna by pine plantation in Uverito promotes a major soil carbon sequestration. The values of the inhibitor additivity ratio (IAR) as for native savanna as pine system, were both>1.0. The total combined inhibition (TCI) was smaller in the pine systems, from which it is possible to infer that a high proportion of microbial biomass was affected by the combination of the inhibitors. Rev. Biol. Trop. 58 (3): 977-989. Epub 2010 September 01.

Cualquier transformación de un ecosistema natural a un sistema agrícola o forestal conduce a una modificación importante no sólo del pool del carbono total, sino también del carbono asociado con la biomasa microbiana. Su cuantificación es importante en la determinación del impacto de las prácticas agrícolas y el cambio de uso de la tierra sobre la calidad del suelo. El objetivo de este estudio fue determinar, a través del método de inhibición selectiva, la biomasa fúngica y bacteriana y la relación (H:B) en suelos de sabana nativa sustituidos por pinares (Pinus caribaea var. hondurensis), para establecer si éstos parámetros son indicadores sensibles de cambios en el contenido de carbono en suelos de Uverito, Venezuela. La relación de aditividad del inhibidor (RAI) y la inhibición total por efecto combinado del inhibidor (ITC) se llevaron a cabo para determinar, si los inhibidores microbianos tuvieron actividad sobre otros organismos para los cuales éstos no estaban destinados. La cuantificación de la biomasa fúngica y bacteriana se llevó a cabo mediante el uso de la cycloheximida como inhibidor fúngico, y la estreptomicina y el cloranfenicol como inhibidores bacterianos. Esta investigación evidencia que este cambio de uso de la tierra ejerció un efecto significativo sobre la biomasa microbiana del suelo, y muestra que en el sistema de pinares existe una dominancia del componente fúngico, en contraste con la sabana nativa, en la cual domina la biomasa bacteriana. La sustitución de la sabana nativa por plantaciones de pino en Uverito, promueve un mayor secuestro del carbono en el suelo. Los valores de la relación de aditividad del inhibidor (RAI) tanto para la sabana nativa como para el sistema de pinares, resultaron ambos >1.0. La inhibición total combinada (ITC) resultó menor en el sistema de pinares; a partir de lo cual, es posible inferir que una elevada proporción de la biomasa microbiana fue afectada por la combinación de los inhibidores.

Microbiota bacteriana aeróbia da conjuntiva de doadores de córnea / Aerobic bacterial microbiota of the conjunctiva of cornea donors

OBJETIVOS: Determinar a microbiota bacteriana aeróbia da conjuntiva de doadores de córnea e seu padrão de suscetibilidade a antibióticos; verificar o número de córneas utilizadas para transplante e a média de tempo de preservação em solução preservante com gentamicina e estreptomicina; traçar o perfil dos doadores e receptores de córnea. MÉTODOS: Espécimes clínicos foram colhidos de saco inferior da conjuntiva de ambos os olhos, de 40 doadores de córnea. As amostras foram inoculadas em ágar sangue azida, ágar chocolate e ágar MacConkey e o antibiograma foi realizado pelo método de Kirby-Bauer. RESULTADOS: A freqüência de cultura positiva da conjuntiva de doadores de córnea foi de 72,5 por cento, sendo que Gram-positivos totalizaram 81,6 por cento e apenas 18,4 por cento das amostras foram identificadas como Gram-negativos. Vancomicina inibiu 100 por cento dos Gram-positivos, ao passo que a sensibilidade dos Gram-negativos à gentamicina foi de 53,8 por cento e à estreptomicina foi de 30 por cento. O sexo masculino predominou entre os doadores e receptores, a média de tempo entre o óbito e a enucleação foi de 2h e a de preservação em solução preservante com gentamicina e estreptomicina foi de 7 dias. Neoplasia e mais de uma causa associada foram as causas de óbito mais freqüentes. O ceratocone foi a principal indicação para transplante (51,7 por cento). CONCLUSÕES: Staphylococcus coagulase negativo foi o microrganismo com o maior número de isolamentos, apresentando sensibilidade variada aos antimicrobianos. A quantidade de córneas utilizadas para transplante foi bastante inferior em relação ao total de captações. O perfil dos doadores e receptores de córnea mostrou-se heterogêneo para grande parte das variáveis analisadas.

PURPOSE: To determine aerobic bacterial microbiota of the conjunctiva of cornea donors and its patterns of susceptibility to antibiotics; verify the number of corneas used for transplant and the average time of preservation in solutions with gentamicin and streptomycin; trace the profile of donors and receptors of cornea. METHODS: Clinical specimens were collected from the inferior bag of the conjunctiva of both eyes of 40 cornea donors. The samples were inoculated into acid blood, chocolate and MacConkey agars, and the antibiogram was performed by the Kirby-Bauer method. RESULTS: The frequency of positive cultures of the conjunctiva of cornea donors was 72.5 percent, with Gram-positive totalling 81.6 percent and only 18.4 percent of the samples were identified as Gram-negative. Vancomycin inhibited 100 percent of Gram-positive microorganisms, while sensitivity of the Gram-negative to gentamicin was 53.8 percent and to streptomycin 30 percent. Most donors and recipients were men, the average time between death and enucleation was approximately 2 hours and preservation in solution with gentamicin and streptomycin was around 7 days. Neoplasms and more than one associated cause were the most frequently causes of death. Keratoconus was the main indication for transplant (51.7 percent). CONCLUSIONS: Coagulase-negative Staphylococcus was the most frequently isolated microorganism, presenting variable sensitivity to antimicrobians. The amount of corneas used for transplant was below the number of available corneas. Donor and receptor profiles were very heterogeneous regarding most of the analyzed variables.

Evaluation of rapid alternative methods for drug susceptibility testing in clinical isolates of Mycobacterium tuberculosis

A study was carried out to compare the performance of a commercial method (MGIT) and four inexpensive drug susceptibility methods: nitrate reductase assay (NRA), microscopic observation drug susceptibility (MODS) assay, MTT test, and broth microdilution method (BMM). A total of 64 clinical isolates of Mycobacterium tuberculosis were studied. The Lowenstein-Jensen proportion method (PM) was used as gold standard. MGIT, NRA, MODS, and MTT results were available on an average of less than 10 days, whereas BMM results could be reported in about 20 days. Most of the evaluated tests showed excellent performance for isoniazid and rifampicin, with sensitivity and specificity values > 90 percent. With most of the assays, sensitivity for ethambutol was low (62-87 percent) whereas for streptomycin, sensitivity values ranged from 84 to 100 percent; NRA-discrepancies were associated with cultures with a low proportion of EMB-resistant organisms while most discrepancies with quantitative tests (MMT and BMM) were seen with isolates whose minimal inhibitory concentrations fell close the cutoff. MGIT is reliable but still expensive. NRA is the most inexpensive and easiest method to perform without changing the organization of the routine PM laboratory performance. While MODS, MTT, and BMM, have the disadvantage from the point of view of biosafety, they offer the possibility of detecting partial resistant strains. This study shows a very good level of agreement of the four low-cost methods compared to the PM for rapid detection of isoniazid, rifampicin and streptomycin resistance (Kappa values > 0.8); more standardization is needed for ethambutol.

Potential use of antibiotic to improve performance of laboratory-reared Nezara viridula (L) (Heteroptera: Pentatomidae)

O antibiótico estreptomicina adicionado à água de beber na concentração de 125 mg/l acelerou o desenvolvimento ninfal de Nezara viridula (L.) (Heteroptera: Pentatomidae), aumentou a sobrevivência e duplicou a longevidade dos adultos, sem afetar a sobrevivência ninfal e o peso dos adultos, quando comparado aos insetos testemunhas. A estreptomicina apresenta potencial para ser utilizada em sistemas de criação do inseto, em especial no tratamento de insetos coletados no campo, reduzindo a introdução de bactérias potencialmente patogênicas na colônia e melhorando a qualidade geral da criação.

Genetic diversity and antimicrobial resistance of enterococcal isolates from Southern region of Brazil

Foram estudadas 455 amostras de enterococos isolados de pacientes moradores da cidade de Porto Alegre, Rio Grande do Sul, Brasil, durante o período de julho 1996 a junho 1997 e foram identificados ao nível de espécies por testes fisiológicos convencionais e analisados sua susceptibilidade aos agentes antimicrobianos. A diversidade genética foi avaliada por eletroforese de campo pulsado ("pulsed-field gel electrophoresis", PFGE) com a enzima de restrição SmaI. A espécie mais freqüente encontrada foi o Enterococcus faecalis (92,8%). As outras espécies identificadas foram: E. faecium (2,9%), E. gallinarum (1,5%), E. avium (1,1%), E. hirae (0,7%), E. casseliflavus (0,4%), E. durans (0,4%) and E. raffinosus (0,2%). A prevalência de amostras com níveis elevados de resistência (HLR) aos aminoglicosídeos foram de 37,8%. HLR para gentamicina foi encontrada em 24,8% das amostras. Nenhuma amostra com resistência adquirida à vancomicina foi isolada. A análise através de PFGE revelou a predominância do grupo clonal A, constituído por amostras isoladas de diferentes materiais clínicos obtidos de pacientes internados em três hospitais. Esses resultados sugerem a disseminação intra e inter-hospital de um clone predominante, composto por amostras de E. faecalis apresentando níveis elevados de resistência a gentamicina, nos hospitais incluídos neste estudo.

Prevalencia de Enterococos resistentes a antibióticos en aguas servidas en el norte de Chile / Prevalence of antibiotic resistant Enterococcus spp in waste waters in the north of Chile

Background: There is little information available in Chile on the distribution of Enterococcus spp in waste water and its implications in transmission of antibiotic resistance through the water cycle. Enterococcus spp are common in nosocomial infections and may spread antibiotic resistance through the food chain. Aim: To determine the presence of antibiotic resistant Enterococcus spp in the sewage of Antofagasta, Chile. Material and Methods: Samples of sewage from two sewage treatment plants and from the Public Hospital of Antofagasta collector were obtained. Enterococcus spp were isolated on m-Enterococcus agar containing ampicillin, vancomycin and streptomycin. The isolates were identified and subjected to biochemical typing (PhPlate). Minimal inhibitory concentration determination was performed by agar dilution technique. Results: High counts of resistant Enterococcus spp were found on the streptomycin plates, lower on ampicillin and very low on vancomycin plates. A total of 63 Enterococcus spp strains were typed and the identification showed 5 different species; E faecalis (65%), E faecium (14%), E hirae (13%), E durans (6%) and E gallinarum (2%). The typing revealed a high diversity among the isolates. Two biochemical phenotypes were predominant, C1 (21 strains) and C6 (7 strains). Both were highly resistant to gentamycin and streptomycin; moderately resistant to ampicillin, cloramphenicol, tetracycline and ciprofloxacin, and with intermediate susceptibility to vancomycin. Both phenotypes were found in the sewage of the hospital collector and in the treatment plants. Conclusions: In the sewage of Antofagasta we found dominating phenotypes of multiresistant Enterococcus spp. Sewage could be an important way of transmission of these microorganisms.

Comparison of four antibiotics for inactivating leptospires in bull semen diluted in egg yolk extender and experimentally inoculated with Leptospira santarosai serovar guaricura

Inactivation of leptospires in pools of semen from three Holstein Friesian bulls, collected in an artificial vagina, was investigated. Spermatic concentration was adjusted in egg yolk citrate extender, submitted to the following treatments: A (control; without antibiotics); B (penicillin, 1,000 UI/mL - streptomycin, 1,000 icg/mL); C (amoxicillin, 1,000 icg/mL); D (ceptiofur sodium, 1,000 icg/mL); E (amoxicillin 1,000 icg/mL - ceptiofur sodium 1,000 icg/mL). Leptospires (2.0 x 10(6) leptospires/mL) were added into the diluted semen. Recovery of leptospires was obtained in modified EMJH semi-solid medium with and without antibiotics. The antibiotics in the concentrations used did not affect means of percentage of progressive motility and individual progressive motility of spermatozoids. Penicillin-streptomycin presented the best results in leptospire inactivation (97.1 percent). Amoxicillin, ceptiofur sodium and their combination at the concentrations studied presented poor results: 59.29 percent; 32.5 percent and 60.36 percent of inactivation, being less effective in leptospire inactivation than penicillin-streptomycin.

Standartization of broth microdilution method for Mycobacterium tuberculosis

Indirect drug susceptibility tests of Mycobacterium tuberculosis was done to investigate the accuracy and feasibility of a broth microdilution method (BMM) for determining minimal inhibitory concentrations of conventional drugs against M. tuberculosis. Test drugs included isoniazid (H), rifampicin (R), ethambutol (E), streptomycin (S) and pyrazinamide (Z). Fifty isolates of M. tuberculosis from patients who had never received drug therapy, and H37Rv strain for control, were evaluated in the system. When comparing this method with the gold standard proportional method in Lowenstein-Jensen medium, sensitivity of 100 per cent for all drugs and specifities of 91, 100, 96, 98 and 85 per cent were observed respectively for H, R, E, S and Z. The BMM was read faster (14-20 days) than the proportional method (20-28 days). The microdilution method evaluated allows the testing of multiple drugs in multiple concentrations. It is easy to perform and does not require special equipment or expensive supplies. In contrast to radiometric method it does not use radioactive material.

Avaliaçäo do sistema semi-automatizado microscan para identificaçäo de testes de sensibilidade de amostras de enterococos / Evaluation of the microscan semi-automated system for species identification and susceptibility testing of enterococci

O objetivo deste estudo foi avaliar a acurácia de um sistema semi-automatizados, os painéis convencionais MicroScan Positive Breakpoint Combo Type 6 (Dade MicroScan Inc., West Sacramento, CA), para identificaçäo de espécie, avaliaçäo da sensibilidade à vancomicina e à ampicilina e detecçäo de alto grau de resistência à gentamicina (HLRGN) e à estreptomicina (HLRST). Esse método foi comparado com a identificaçäo bioquímica convencional e com o método de diluiçäo em ágar (DA) para avaliaçäo de sensibilidade a antimicrobianos. Dentre as 211 amostras testadas (184 E.faecalis, 21 E.faecium e 6 näo-faecalis-näo-faecium), 95 por cento dos E.faecalis e 67 por cento dos E.faecium foram idetificados corretamente pelo MicroScan. O microScan apresentou 99,5 por cento de concordância com o método de DA para testes de sensibilidade à vancomicina e o HLRGN e o HLRST foi detectado em 92 por cento (33/36) e 84 por cento (31/37) das amostras, respectivamente. Os resultados do presente estudo mostram que este método semi-automatizado apresenta dificuldades na identificaçäo de espécies diferentes de E.faecalis, além de elevadas taxas de erros muito graves para ampicilina (11 por cento), gentamicina (8 por cento) e estreptomicina (16 por cento)

Comparaçäo entre a eficácia antimicrobiana de três diferentes meios de preservaçäo da córnea / Antimicrobial efficacy of three distinct corneal storage media

A endoftalmite bacteriana pode ser considerada como uma complicaçäo frequente da ceratoplastia penetrante, se comparada com a incidência da mesma encontrada nas cirurgias de catarata, 0,8 e 0,09 por cento, respectivamente. A segurança do transplante de córnea pode ser aumentada adicionando outros agentes bactericidas à gentamicina, capazes de atingir o espectro näo alcançado pela mesma. Para comparar a eficácia antimicrobiana, foram empregados 52 anéis córneo-esclerais provenientes de córneas humanas, distribuidos em 3 diferentes meios de preservaçäo de córnea, o primeiro contendo gentamicina (optsol), o segundo gentamicina e estreptomicina (optsol GS) e o terceiro gentamicina, estreptomicina e penicilina G (likorol). As culturas dos anéis córneo-esclerais apresentaram-se positivas em 6 amostras (11,5 por cento), sem diferença estatisticamente significativa entre os diferentes grupos (p>0,05). Foram identificados os seguintes microrganismos: Candida albicans (no Optsol GS e Likorol), Staphylococcus epidermidis (no Optsol) e Streptococcus faecali (no Likorol)

A genetic study of a Staphylococus aureus plasmid involving cure and transference

High frequency transfer and elimination of drug resistance may indicate an extrachromosomal inheritance of genetic determinants. This study shows the cure and transfer of a small plasmid and tetracycline resistance in Staphylococcus aureus 1030 (55) Tetr strains. Several methods are available for plasmid elimination. We used ethidium bromide, an agent that binds to DNA, and thus inhibits DNA polymerase. This caused a high frequency of loss of the small plasmid and resistance to tetracycline. Transfer of tetracycline resistance was done in a mixed culture at a frequency of 10(-6). This type of study is very important to physicians and epidemiology investigators and provides better knowledge on antibiotic-resistance mechanisms that may occur in vivo in a hospital environment.