Multiple Antimicrobial Resistances of Bacteria Isolated from Samples of Recreational Beach in Gaza Strip

Abstract

The aim of the present study is a document the occurrence of pathogenic bacteria in seawater, beach sand and mussel samples collected from five locations along the coast of the Gaza strip and to determine the extent that these bacteria possess multi-drug resistance. Pathogens were isolated and identified by microbiological and biochemical methods and their susceptibility was determined against different antimicrobial agents by using the agar disc diffusion method and according to NCCLS (National Committee for Clinical and Laboratory Standard) guidelines. In most locations, cultivable fecal indicator bacteria such as fecal coliform (FC) and fecal streptococci (FS) were more abundant in the sand (an average of 846.6 cfu/100 g) than in the sea water (579.5 cfu/100ml) and the number of FS in sand samples were higher than that of FC. Population density of both FC and FS was generally higher at Khan Yunis, South of Wadi Gaza outlet and North of Wadi Gaza outlet. Mussels were found to accumulate more FS than FC. The results also indicated that all sites comply with mandatory standards for water quality in the directive, and only the northern side of Wadi Gaza outlet do not achieve the more stringent guideline values for both FC and FS in water. Conventional biochemical tests identified 411 isolates belong to four bacterial groups of Enterobacteriaceae (42.4%), Enterococci (17.6%), Pseudomonas aeruginosa (23.7%) and Staphylococci (16.3%). Enterobacteriaceae, Enterococci, Pseudomonas aeruginosa and Staphylococci isolates were tested for their susceptibility to 10, 6, 8 and 10 antimicrobials respectively. The incidence of multiple resistances for the four bacterial groups from the different sample types (mussels, seawater and beach sand) and from the different sampling locations are presented. Amongst the Enterobacteriaceae isolates, 94.3% were resistant to at least one antimicrobial agent and 80.5% exhibited simultaneous resistance to more than one agent i.e., they are Multiple Antimicrobial Resistance (MAR). It also found that 100% of Enterococci isolates were resistant at least to one antimicrobial and 89.4% were MAR. For Pseudomonas aeruginosa isolates, 68.5% were resistant at least one agent and 43.8% were MAR. Staphylococci isolates showed that 98.4% were resistant to at least one agent and 88.6% were MAR. The greatest frequency of resistant in all Enterobacteriaceae isolates was found against Tetracycline (67.9%) and Amoxicillin-clavulanic (56%). For the Enterococci, the highest resistance was against Vancomycin (84.8%) and Ampicillin (80.3%). Pseudomonas aeruginosa highest resistant was against Piperacillin (55.1%). The highest resistance of Staphylococci isolates was against Penicillin )91.8%(, Vancomycin )68.9%( and Oxacillin )62.3%(. All the calculated values of MAR index were higher than 0.2 demonstrating that the area of study is considered a high risk source of contamination environment where antimicrobial agents use are common. In conclusion, the results of the present study shows the widespread occurrence of antibiotic resistant bacteria in all types of samples tested and from all locations along the coast of the Gaza strip and their presence may become a potential human health hazard. Consequently efforts should be exerted to minimize the discharge of untreated or partially treated sewage from both domestic and hospitals sources which represent the prime source of antimicrobial agents in the marine environment in this area.