Introduction The city of Fortaleza (Ceará State, Brazil), with 2.2 million inhabitants, is currently disposing of its untreated sewage directly into the ocean. As municipal sewage invariably contains pathogenic bacteria, its collection and direct disposal into the ocean via dispersal pipes represents a health hazard to the population extensively using the coastal zone for recreation. Prior to constructing a reasonably safe sewage ocean dispersal system, reliable studies of marine currents and their movements are mandatory. Constant monitoring of the operating dispersal system is necessary to avoid its damage and to establish the impact of continuous raw sewage discharge on the marine environment. In the recent local studies [7, 16], high Most Probable Number (MPN) values for total coliforms and fecal coliforms on the Fortaleza beaches close to the sewage discharge into the ocean were detected. Enteropathogenic Escherichia coli isolated and classified in these studies indicate the health hazard to swimmers off the beaches. In the present research we followed the legislation of the (Brazilian) National Council for the Environment (CONAMA) in order to monitor the beaches through the evaluation of the MPN of total and fecal coliforms and to estimate the balneability grade of the beach seaside environment. Some strains of E. coli were isolated and enteropathogenic strains serotyped, checking their toxicity through the use of biochemical and molecular techniques. Materials and methods Bacteriological analyses of seawater from three main beaches in Fortaleza (Formosa, Meireles and Diários) (Fig. 1) were performed covering the period of nine months, from July 1996 to March 1997. Thirty-six samples per beach were collected for a total of 108 samples. The MPN of total and fecal coliforms per 100 ml of seawater was determined in each sample. Isolated strains were cultured on EMB agar and identified by conventional methods [1, 6, 13]. 221 Regine H.S.F. Vieira 1 Dália P. Rodrigues 2 Norma S.S. Evangelista 1 Grace N.D. Theophilo 2 Eliane M.F. Reis 2 1 Laboratório de Ciências do Mar, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil 2 Fundação Oswaldo Cruz, Rio de Janeiro, Brazil Received 28 May 1998 Accepted 28 July 1998 Correspondence to: Regine H. S. F. Vieira. Laboratório de Ciências do Mar. Universidade Federal do Ceará. Av. da Abolição 3207. Meireles. 60165-081 Fortaleza. Ceará. Brazil. Tel.: +55-852426422 ext. 221. Fax: +55-852428355. E-mail: regpoema@labomar.ufc.br RESEARCH ARTICLES INTERNATL MICROBIOL (1998) 1:221–224 © Springer-Verlag Ibérica 1998 Colimetry of marine waters off Fortaleza (Ceará State, Brazil) and detection of enteropathogenic Escherichia coli strains Summary Bacteriological analyses of seawater from three main beaches in Fortaleza, Brazil were performed during 1997. Thirty-six samples per beach were collected for a total of 108 samples. For Meireles Beach, 44% of the samples had MPN total coliforms values of at least 1100 or over 2400/100 ml, followed by Formosa and Diários beaches showing lower counts. For fecal coliforms the highest numbers were demonstrated for Formosa, followed by Meireles and Diários beaches in this descending order: 13.0%, 11.1% and 8.3%, respectively. Escherichia coli strains were identified in 76.8% of the 108 samples. Among 295 strains of E.coli, 21 belonged to serogroups O25, O26, O91, O112, O119, O158 and O164. Strains from serogroup O26 were tested using PCR, ELISA and Vero cells to detect Verotoxins VT1 and VT2 and all strains were negative. No LT and ST, as determined by ELISA and suckling mice assays, were detected among the 295 strains. All strains of E. coli were sensitive to ampicillin, cephalothin, gentamicin, tetracycline, sulfametox-trimethoprim, chloramphenicol and ciprofloxacin. Although the E. coli strains were not toxigenic, their presence in high numbers could be of public health significance. Key words Escherichia coli · Enteropathogenic serogroups · Marine waters · Sewage disposal · Public health