Occurrence and virulence properties of Vibrio and Salinivibrio isolates from tropical lagoons of the southern Caribbean Sea.

The Vibrionaceae are Gram-negative bacteria present in marine and estuarine environments worldwide, including several species known as important pathogens to humans and aquatic organisms. The aim of this research was to investigate the occurrence and virulence properties of Vibrio and Salinivibrio isolated from lagoons at Cuare Wildlife Refuge and Margarita Island in the southern Caribbean Sea. Water, plankton and oyster samples were collected during October 2011 and March 2012 and examined by specific PCR and culture methods. Vibrio genus DNA was detected in 95% of samples, while the intergenic spacer region (ISR) of Vibrio cholerae and the genes that code for the thermolabile direct haemolysin (tl) of Vibrio parahaemolyticus and the haemolysin/cytolysin (vvhA) of Vibrio vulnificus were absent or amplified in low proportions (23, 5, and 0%, respectively). Nine isolates from water and plankton were confirmed as Vibrio or Salinivibrio by phenotypic tests, 16S rRNA gene sequencing and phylogenetic analysis. All the isolates presented similar patterns of virulence factors, in which the genes ctxA (encoding for cholera toxin), tl and vvhA were lacking, whereas seven isolates displayed antibiotic resistance against ampicillin and cephalosporins. The 16S rRNA phylogenetic analysis showed the clustering of Vibrio isolates in three main clades: the plankton isolate from Cuare Wildlife Refuge formed a group with V. cholerae and Vibrio mimicus while the Margarita isolates clustered with sequences from the harveyi clade and Salinivibrio. This is the first time that Salinivibrio species are reported in tropical lagoons of the Caribbean Sea with antibiotic resistance.

Sensibilidad a los antimicrobianos de cepas de Salmonella aisladas en granjas porcinas del estado Zulia / Antimicrobial susceptibility of Salmonella strains isolated from pig herds in Zulia state

El objetivo de este estudio fue determinar los patrones de resistencia a los antimicrobianos de diferentes cepas de Salmonella aisladas en granjas de cerdos del estado Zulia. Para este fin se evaluaron mediante la técnica de Bauer-Kirby, 126 cepas de Salmonella aisladas de heces de cerdos portadores asintomáticos. Las pruebas de sensibilidad antimicrobiana demostraron que los más altos niveles de resistencia fueron frente a la sulfamida (54 por ciento), tetraciclina (40 por ciento), ácido nalidíxico (29 por ciento) y ampicilina (23 por ciento). Sin embargo, sensibilidad superior al 95 por ciento fue encontrada frente a la ceftriaxona, gentamicina, apramicina y colistina. El treinta por ciento de las cepas mostraron multirresistencia (MR) a los antimicrobianos, siendo el patrón de resistencia ASuT (7,14 por ciento) el más frecuente. Los resultados obtenidos indican que la proporción de cepas de Salmonella de origen porcino con características de multirresistencia a los agentes antimicrobianos es medianamente elevada (30 por ciento) y esta multirresistencia puede afectar a cualquier serotipo. Desde ese punto de vista, la infección de las personas por cepas de Salmonella de origen porcino conlleva a un riesgo potencial de presentar dificultades en el tratamiento específico.

The aim of this study was to determine antimicrobial resintance paterns of different strains of Salmonella isolated in pig farms of the Zulia State. To achieve these goals 126 strain Salmonella were screened by Kirby-Bauer method, colleted from heces of pigs asymptomatic. Antimicrobial susceptibility tests showed that the highest level of resistance was against Sulphonamides (54%), Tetracycline (40%), Nalidixic acid (29%) and Amplicillin (23%). However, susceptibility superior to 95% was found to Ceftriaxone, Gentamycin, Apramycin and Colistin. Thrity percent of the strains showed multirresitance, being the patterns resistance ASuT (7.14%) the most frequent. The results indicate the proportion of strain of Salmonella of pig origin with characteristics of multiresistance to the antimicrobial agents is elevated (30%) and this multiresistance could affect to anyone serotype. From this point of view, the infection of the people by isolates of Salmonella from swine origin entails a potential risk to present difficulties in the specific treatment.

First isolation of a VIM-producing Klebsiella pneumoniae from a seven-year-old child in Venezuela.

BACKGROUND: VIM-type metallo-betalactamases (MBLs) exhibit hydrolytic activity against most betalactam antibiotics, including carbapenems. So far, VIM-type-producing Klebsiella pneumoniae isolates had not been reported in Latin America. METHODOLOGY: In July 2005, a carbapenem-resistant Klebsiella pneumoniae was isolated from a urine sample collected from a 7-year-old girl hospitalized at the Hospital de Niños "J. M. de los Ríos" in Caracas, Venezuela. This strain was identified using conventional biochemical tests. The susceptibility analysis was conducted by disk diffusion, and MICs for Imipenem and Meropenem were performed by agar dilution. For the phenotypic detection of MBL we used the Imipenem-EDTA/SMA double-disk diffusion method. The hydrolytic activity against carbapenems was determined by the Masuda microbiological method. Purified protein was subjected to isoelectric focusing (IEF). Detection of antimicrobial resistance genes was performed by PCR amplification with specific VIM primers. RESULTS: The strain showed resistance to most betalactam antibiotics, quinolones and amynoglicosides, but remained susceptible to Aztreonam and Cefepime. The use of phenotypic and microbiological methods detected the presence of a metallobetalactamase. By IEF we visualized three bands at pI 5.4, 7.6 and 7.9, corresponding to reduced-spectrum betalactamases, and a band at pI 5.8 that corresponded to the metallobetalactamase. PCR screening of bla genes revealed the presence of blaVIM, with an amplicon of 261 bp. CONCLUSIONS: This is the first report of a MBL-mediated carbapenem-resistant Klebsiella pneumoniae in Latin America, which constitutes a public health concern in our region since their transference to other microorganisms with multiple antibiotic resistance mechanisms will increase the antimicrobial resistance problem.

Reduced susceptibility to quinolones among Salmonella serotypes isolated from poultry at slaughter in Venezuela.

Today there are recognized global "hot spots" that are areas in which nontyphoid Salmonella serotypes have been reported to have a high prevalence of quinolone resistance. There is concern that resistant strains can be disseminated from these localized geographical areas by travelers or via commercial food products. The objective of this article is to report a high frequency of reduced susceptibility to first- and second-generation quinolones among nontyphoid Salmonella isolates from poultry at slaughter in two processing plants belonging to the largest poultry integration companies in Zulia State, Venezuela. Nearly all (74 of 77; 96.1%) of the isolated strains were resistant to nalidixic acid, and 3.7% were resistant to ciprofloxacin; most (45 of 77; 58%) exhibited reduced susceptibility to ciprofloxacin and norfloxacin (15 of 77; 19.5%). In contrast, all of the isolates were susceptible to beta-lactamic antimicrobial drugs. Ninety-three percent (72 of 77) of the isolates were either Salmonella Parathyphi B or Salmonella Heidelberg, which have been reported as invasive Salmonella. The predominant serotypes in each slaughter plant showed different antimicrobial susceptibilities, only having in common their high resistance to nalidixic acid, suggesting that different clones disseminated in each commercial integration. The detection of high frequency of reduced susceptibility to first- and second-generation quinolones among nontyphoid Salmonella isolates from fresh poultry during processing is noteworthy. Resistance to quinolone drugs will not only make antimicrobial therapy more complicated if foodborne disease results, but also these quinolone-resistant strains can disseminate from this local hot spot to other geographical areas, spreading the resistance against this important antimicrobial drug.

Vibrio cholerae O1 en Venezuela 1997-1999: sensibilidad a los antibióticos / Vidrio cholerae 01 in Venezuela 1997-1999: sensitivity of antibiotics

El presente estudio reporta los resultados de la vigilancia de la sensibilidad antibióticos en 202 cepas de V.cholerae O1 aisladas en Venezuela, desde enero de 1997 hasta diciembre de 1999. Se muestran los registros de las primeras cepas con resistencia a algunos antibióticos en Venezuela (12,2 por ciento), cefotaxima (15,4 por ciento), ceftriaxona (3,2 por ciento) y tetraciclina (0,6 por ciento), las cuales fueron aisladas en el brote detectado en el estado Zulia y que expandió por 14 entidades federales en 1997. También se demuestra el surgimiento de multiresistencia a los antibióticos en cepas aisladas en un segundo brote que inició en el estado Delta Amacuro y se extendió a los estados Sucre, Nueva Esparta, Monagas, Anzoátegui y Miranda. Los aislamientos resultaron resistentes a la ampicilina, ampicilina-sulbactam, co-trimoxazol y al agente vibriostático 0129, permaneciendo sensibles al ácido nalidíxico, cefotaxima, cetriaxona, ciprofloxacina, cloranfenicol, doxiciclina, gentamicina, norfloxacina, tetraciclina y tobramicina. Posteriores estudios deberán realizarse para determinar los mecanismos genéticos para la adquisición de esta resistencia a antibióticos.

Programa de control de calidad de Discos antibióticos / Quality of control program of antibiotics disks

La prueba de Antibiograma se usa rutinariamente para medir la susceptibilidad a los antibióticos de las bacterias aisladas en muestras clínicas. Asegurar la calidad de los discos de antibióticos es indispensable para que se produzcan resultados confiables y oportunos en el Antibiograma. Para ello se estableció un programa de control de calidad de los discos antibióticos. Se realizaron 336 mediciones durante 6 meses, con sólo 5(1,2 por ciento) resultados fuera del rango establecido y 27(8,0 por ciento) resultados en los límites. De los 5 resultados obtenidos fuera de los rangos, 4 de ellos fueron valores por debajo del límite inferior, todos ocurrieron el mismo día, lo que sugiere algún error en la técnica. De los 14 antibióticos probados, 9 de ellos tuvieron tendencia a la baja y 5 con tendencia a la alta. Debido a resultados en los límites inferiores o por debajo se descartaron 6 viales. El programa de Control de Calidad de los discos de Antibióticos ha sido un éxito, todo el personal ha tomado conciencia de que el control de calidad en un laboratorio es una obligación en beneficio del paciente