Introduction: Like many other costal cities, Galveston Island is more populated during the summer months where thousands of visitors come to enjoy the beach and engage in water activities. Often, accidents occur and traumatic injuries at the beach are frequently contaminated with seawater bacteria that are not typically found in other wounds. This poses a problem to the treating physician, often a plastic surgeon who is consulted for an acute traumatic wound to the extremity or a chronic non-healing traumatic wound. Usually, empiric antibiotics are prescribed to cover native skin flora (gram positives) and the wound culture and sensitivity results return much later. Numerous studies at other coastal cities have found Vibrio species in seawater and linked it to the development of severe cellulitis, sepsis, and even death. These studies suggest that seawater contaminated wounds can be fatal and must be treated early and aggressively for proper wound healing and functional recovery of the injured extremity. The purpose of this study is to identify the most common pathogens found in Galveston seawater and their antibiotic sensitivities in order to provide early rational antibiotic recommendations. Methods: We collected 50 ml of seawater from 25 locations along Galveston beach area in Texas. The samples were obtained during early Fall with a water temperature of 28.3°C. Samples were collected approximately 1 foot below the air-surface interface from locations where water depth is approximately 2 feet. Each sample was plated on a Blood agar, MacConkey agar, Columbia agar (CNA), and Sabouraud’s dextrose agar with a calibrated 10 ul loop and incubated at 37°C overnight. Three ml of each sample was also added to 8 ml of thioglycolate broth and incubated at 37°C overnight, then plated on the 4 types of agar listed above in the same fashion. For each sample, colonies derived from direct plating were compared with colonies derived from the thioglycolate broth. All unique colonies from each sample were subcultured using appropriate media for pure isolates. Identification and antibiotic sensitivity tests were done using Positive Breakpoint Combo Panel 9 (Microscan®) for Gram-positive colonies and Negative Breakpoint Combo Panel 11 (Microscan®) for Gram-negative colonies. Antibiotics tested in the Gram-positive panel included penicillin, ampicillin, vancomycin, levofloxacin, chloramphenicol, tetracycline, erythromycin, ciprofloxacin, and rifampin. Antibiotics tested in the Gram-negative panel included cefepime, levofloxacin, lomefloxacin, piperacillin, piperacillin/tazobactam, amikacin, gentamycin, tobramycin, imipenem, cefoperazone, ceftazidime, ciprofloxacin, chloramphenicol, ticarcillin/K clavulanate, Bactrim, ceftriaxone, mezlocillin, tetracycline, aztreonam, cefotetan, cefotaxime, ampicillin/sulbactam, cefuroxime, cefazolin, Augmentin, cefamandole, ampicillin, and cephalothin. Results: All 25 samples grew 2 or more species of bacteria. Fifteen species with 33 biotypes were isolated: 12 species (24 biotypes) were gram-negative and 3 were gram-positive (9 biotypes). The 3 most common isolates were single biotypes of K. pneumoniae (23/25 samples), E. coli (13/25), and E. faecium (13/25). All gram-negative isolates were sensitive to levofloxacin, cefepime, and lemofloxacin. All gram-positive isolates were sensitive to penicillin and ampicillin. Conclusion: Analysis of Galveston Beach seawater revealed both gram-positive and negative pathogens, with K. pneumoniae, E. coli, and E. faecium being the most common. Since all gram-positive isolates were sensitive to penicillin and all gram-negative isolates were sensitive to levofloxacin, a combination of oral penicillin with oral levofloxacin could be used for early empiric antibiotic coverage for penetrating wounds contaminated by seawater.
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