Detection and antimicrobial resistance profiling bacteria isolated from seawater, major bathing beaches of Cox’s Bazar, Bangladesh

Abstract

Coastal bathing waters are potential reservoirs of pathogenic bacteria, posing serious risks to public health. Cox’s Bazar, the world’s longest natural beach and a highly visited tourist destination in Bangladesh, lacks updated data on microbial safety. This study aimed to assess the bacteriological quality of seawater from major bathing sites in Cox’s Bazar, focusing on two key pathogens and their antimicrobial resistance patterns. Seawater samples were systematically collected from four popular beaches—Sugandha, Laboni, Him Chori, and Inani. Bacterial isolation was carried out using selective media: MacConkey agar for Escherichia Coli, TCBS agar for Vibrio cholerae. Presumptive isolates were purified, confirmed by PCR, and subjected to antimicrobial susceptibility testing (AST) against 14 commonly used antibiotics following standard disc diffusion methods. A total of 260 bacterial isolates were confirmed, comprising 114 E.coli, and 146 V. cholerae. AST results showed varied susceptibility patterns. Overall, most isolates exhibited high susceptibility to imipenem, doxycycline, and chloramphenicol, while notable resistance was observed against vancomycin and ampicillin. V. cholerae isolates demonstrated the highest proportion of susceptibility, whereas E.coli showed more diverse resistance profiles. The detection of pathogenic bacteria and their multidrug-resistant traits in bathing waters of Cox’s Bazar highlights a significant public health concern. Continuous monitoring and proper management strategies are urgently needed to ensure safe recreational water quality and prevent waterborne disease outbreaks.