ENVIRONMENTAL PARAMETERS AND ANTIMICROBIAL SUSCEPTIBILITY OF ENTEROBACTERIACEAE ISOLATED FROM ESTUARINE WATERS OF SÃO VICENTE

Diseases transmitted by water consists a serious public health problem and enterobacteria are the main group of microorganisms responsible for outbreaks in humans. Such pathogenic bacteria proliferate in water polluted by domestic and industrial sewage and reach the population through seawater contact. The aim of the present work was to study environmental parameters as well as to identify Enterobacteriaceae species and their antimicrobial susceptibility in water samples collected from the estuarine area of São Vicente city (São Paulo State, Brazil). Strains were identified by using traditional biochemical tests described in literature and antimicrobial susceptibility tests were carried out using the disk diffusion method. Out of 26 samples, Escherichia coli was the most frequent species (40.1%), followed by Citrobacter, Enterobacter and Klebsiella. The most effective drugs against the tested microorganisms were gentamycin, netilmicin, ciprofloxacin and cefepime. Since these bacteria are commonly found in seashore contaminated by sewage effluents, it can be concluded that estuarine waters of São Vicente are polluted and potentially capable of causing diseases and spreading pathogenic bacteria to human communities.


INTRODUCTION
The increasing interest in scientific studies detecting pathogenic bacteria in seawater is due to the several outbreaks of infectious diseases originated from this source.
The occurrence of such organisms in polluted waters mainly results from domestic and industrial effluents that alter the physical and chemical atmospheric conditions.Aquatic ecosystems, which include freshwater (fountains, lakes, rivers), estuarine and oceanic waters, present an autochthonous microbial flora and other transitory microorganisms that arrived through the air, soil or industrial and domestic spill (10).
Outbreaks of diseases transmitted by water can be caused by Enterobacteriaceae, which proliferate in polluted waters.However, industrial pollutants together with the residues and sewage from the Port of Santos and other close cities have led to a severe environmental degradation significantly reflecting in the social and public health areas.
The configuration of São Vicente's seafront, in a region that is not opened to the sea, hinders the circulation of water and the consequent dilution of pollutants, directly interfering in the seawater quality in some beaches.Several water courses that drain the main beaches of São Vicente are contaminated by sewage, and therefore directly influence the beaches quality, making them inappropriate for bath and leisure.
Sewage from several human activities has played an important role in the spread of pathogenic microorganisms to the environment and constitutes a risk to the public health (10).Additionally, bacteria resistant to antibiotics are spread at different densities to the atmosphere because of the crescent and frequent indiscriminate use of drugs in medicine, veterinary medicine and agricultural practices (3).
The lack of scientific research on the subject and the possibility that enterobacteria isolated from the sea environment are originated from coastal waters polluted by sewage and sanitary effluents make this study of great importance.

Analysis of the antimicrobial susceptibility profile of Enterobacteriaceae from São
Vicente's estuarine waters can benefit the population by contributing to a better knowledge for the establishment of goals for its control.

Samples
Twenty-six estuarine water samples were collected in 500ml flasks, previously sterilized within the standards of the American Public Health Association -APHA, 1995 (1), from August 2004 to May 2005, using a boat and a collector positioned at one-meter depth and 100 meters away from the estuary margin.
Sampling points were established at three different areas in São Vicente's estuarine system (Table 1) and recorded using Global Positioning System (GPS) equipment.

RESULTS
In the analysis period, there was a significant variation in the salinity indexes including a decrease in values from March 2005, while water temperature showed a slight variation (Fig. 1).The pH values were stable throughout the period.

DISCUSSION
Environmental parameters of São Vicente's estuarine waters did not reveal significant variations, except for salinity, since the seasonal pluviometric indexes from November (2004) to May (2005) were significantly higher than in other periods.
The data obtained confirmed the presence of Enterobacteriaceae in the estuarine waters, especially Escherichia coli, a specific fecal pollution indicator which also constitutes a risk to human health (9,10).
Fecal coliforms are frequently identified in tropical superficial waters, consisting of Escherichia, Klebsiella and Enterobacter or Citrobacter, the most common bacteria (4).Our data corroborated the studies carried out by CETESB (11,12), which detected that Santos-São Vicente's estuarine system has been, for a long time, one of the most polluted areas in the São Paulo State seashore.The contact with polluted water has been directly related to outbreaks of infections, as mentioned by Haile et al. (5), who observed an increase in the level of adverse risks to the health as a consequence of swimming practices in seawaters polluted by non-treated sewage.
Therefore, the treatment of effluents at the coastal sea area is extremely necessary, considering appropriate health conditions not only for the general population, but also for the coastal communities which accounts for the highest demographic density index in all seasonal periods.The urgency for the imposition of basic sanitary measures constitutes an effort that should be adopted by the public administration, as indicated by Pisciotta et al. (8).
In addition, the evaluation of the antibacterial drugs susceptibility allowed the observation of a significant profile, especially regarding gentamycin, netilmicin and ciprofloxacin.Resistance was slight to cefepime and cefoxitin, and amoxicillin/clavulanic acid and ampicillin were responsible for the highest percentages of resistant strains.Results revealed a predominance of bacteria resistant to β-lactamic drugs, which is worrying as such microorganisms can contribute, at the environmental level, to the spread of genetic markers to other bacteria as well as to the hindering of treatments with β-lactamic drugs, the antibiotics group most used in the control of infectious diseases.According to the World Health Organization (WHO), 80% of the diseases that occur in developing countries are caused by water contamination and more than 15 million children aged 0-5 years old die every year (10).