ABSTRACT
This study reports the occurrence and the effect of the environmental factors on the spatial and temporal distribution of the dinoflagellate Akashiwo sanguinea (Hirasaka) Hansen & Moestrup in estuarine waters of northeastern Brazil. Samples were collected at seven stations from March 2007 to February 2008 during high tide and low tide, using Van Dorn bottles. The samples were immediately fixed with Lugol and analyzed with the Utermöhl method. Water samples were also collected for the identification of the hydrological characteristics of the area. Akashiwo sanguinea occurred throughout the annual cycle and at all sampling sites with densities ranging between 5 and 410 x 103 cells.L–1. The highest densities were recorded at low tide, especially during the months of the rainy season (July: 210 x 103 cells.L–1; August: 410 x 103 cells.L–1). Density values were within the normal range and blooms were not detected. Despite being common in the area, the species showed preference for sites with high concentrations of orthophosphate and total dissolved phosphorus and with salinity in the mesohaline regime.
Este estudo relata a ocorrência e o efeito dos fatores ambientais na distribuição espacial e temporal do dinoflagelado Akashiwo sanguinea (Hirasaka) Hansen et Moestrup em águas estuarinas do Nordeste do Brasil. As amostras foram coletadas em sete estações, durante o período de março 2007 a fevereiro 2008 durante os regimes de preamar e baixa-mar, com o auxílio de garrafas tipo Van Dorn. As amostras foram imediatamente fixadas com lugol e analisadas pelo método de Utermöhl. Amostras de água foram também coletadas para a identificação das características hidrológicas da área. Akashiwo sanguinea ocorreu em todo o ciclo anual e em todos os locais de coleta com densidade variando de 5 a 410 cells.L–1 x 103, sendo as maiores densidades registradas na baixa-mar, principalmente, durante os meses do período chuvoso (julho 210 cells.L–1 x 103, agosto 410 cells.L–1 x 103). Os valores quantitativos estiveram dentro dos padrões normais, não tendo sido detectados florescimentos com conotações de blooms. Apesar de ser frequente na área, a espécie mostrou preferência pelos locais com maiores concentrações de ortofosfato dissolvido e fósforo total dissolvido e salinidade compreendida no regime mesoalino.
Subject(s)
Dinoflagellida/classification , Brazil , Estuaries , Environmental Monitoring/methods , Population Density , Population Dynamics , SeasonsABSTRACT
La llegada al ambiente de bacterias antibiótico-resistentes compromete su calidad higiénico sanitaria. Se analizó la prevalencia de diferentes especies de Enterococcus en aguas del estuario de Bahía Blanca y sus patrones de resistencia a los antibióticos. Se identificaron bioquímicamente 103 aislamientos . Para evaluar la resistencia a antibióticos se implementó la técnica de difusión en agar utilizando discos de vancomicina (Van 30 µg), gentamicina (GenH 120 µg), estreptomicina (StrH 300 µg), teicoplanina (T 30 µg), ampicilina (Am 10 µg) y ciprofloxacina (CIP 5 µg), según normas del Clinical and Laboratory Standards Institute. Se identificaron siete especies de Enterococcus; Enterococcus faecium y Enterococcus faecalis resultaron ser las más frecuentes. El 1,9% de los enterococos presentó resistencia de alto nivel a los aminoglucósidos y no hubo aislamientos con resistencia simultánea a StrH y GenH. El 12,6% de los aislamientos resultó resistente a CIP. No se detectaron resistencias a los glucopéptidos, ni a la Am. El 34% de los aislamientos fue sensible a todos los antibióticos probados. Tradicionalmente, la vigilancia de la dispersión de resistencias bacterianas se realiza con microorganismos de muestras clínicas. Los hallazgos de este trabajo constituyen un dato relevante para el control de cepas resistentes, las que se creían circunscriptas al ámbito hospitalario y que, sin embargo, se encuentran circulando en el ambiente.
The introduction of antibioticresistant bacteria to the environment, affects its hygienic-sanitary quality. The objective of this work is to study the prevalence and the antibiotic resistance patterns of enterococci species isolated from Bahía Blanca estuarine waters. One hundred and three isolates were biochemically identified as Enterococcus spp. The diffusion technique was implemented, by using disks of: vancomycin (Van 30 µg), gentamicin (GenH 120 µg), streptomycin (StrH 300 µg), teicoplanin (T 30 µg), ampicillin (Am 10 µg) and ciprofloxacin (CIP 5 µg) according to the Clinical and Laboratory Standards Institute. Seven Enterococcus species were identified, being Enterococcus faecium and Enterococcus faecalis the most frequent. High level resistance to aminoglycosides was shown by 1.9% of the enterococci whereas 12.6% of the isolates were resistant to CIP. No isolates showed simultaneous resistance to StrH and GenH. Neither resistance to glycopeptides nor to Am was detected. Thirty four per cent of the isolates exhibited susceptibility to all antibiotics tested. Surveillance studies on antimicrobial resistance are usually based upon microorganisms isolated from clinical samples. The findings of this work constitute relevant data for the control of resistant strains, which were believed to be circumscribed to the hospital environment, but are also widespread in the natural sites.
Subject(s)
Drug Resistance, Bacterial , Enterococcus/drug effects , Fresh Water/microbiology , Water Microbiology , ArgentinaABSTRACT
The appearance of enteric disease outbreaks associated with the use of waters considered bacteriologically suitable, calls for the search of new and more precise indicators. Samples of estuarine water were collected in order to quantify E. coli and E. coli ATCC 13706 somatic coliphages and to compare the usefulness of the latter to detect faecal contamination when the concentration of traditional indicators is not quantifiable. Statistical analyses suggested the division of sampling sites into two groups: group I and group II, according to the minor or major level of faecal pollution respectively registered. In group II a high correlation between the coliphages and E. coli (r: 0.73 p<0.01) was detected. E. coli always exceeded coliphage abundance. In group I, this relationship was statistically significant (r: 0.55 p< 0.05), coliphage counts were higher than those of E. coli and were detected in the absence of the latter. In summary, the use of E. coli ATCC 13706 somatic coliphages is proposed as a complementary tool for the diagnosis of the level of faecal contamination of estuarine waters, especially in areas of low pollution.
La aparición de brotes de enfermedades víricas entéricas asociadas al uso de aguas bacteriológicamente aptas impone la búsqueda de nuevos y más precisos indicadores de contaminación. Se recolectaron muestras de agua estuarina, donde se cuantificaron simultáneamente la bacteria E. coli y los colifagos somáticos de E. coli ATCC 13706, a fin de evaluar la utilidad de estos últimos para detectar contaminación fecal cuando la concentración de los indicadores tradicionales no es cuantificable. Los resultados estadísticos sugirieron la división de las estaciones de muestreo en dos grupos, I y II, de acuerdo con el menor o mayor nivel de contaminación fecal registrado, respectivamente. En el grupo II se detectó una alta correlación entre los recuentos de colifagos y de E. coli (r: 0,73 p<0,01). Asimismo, en este grupo la abundancia de E. coli siempre superó a la de colifagos. En el grupo I la correlación fue estadísticamente significativa (r: 0,55 p < 0,05), pero de mediana magnitud, los recuentos de colifagos superaron a los de E. coli, y éstos fueron detectados aun en ausencia de la bacteria. En conclusión, los colifagos somáticos de E. coli ATCC 13706 serían una herramienta accesoria en el diagnóstico del nivel de contaminación fecal de aguas estuarinas, sobre todo en áreas donde ésta es baja.
