ABSTRACT
BACKGROUND: The worldwide emergence of multi-drug resistant bacteria has become a health crisis, as fewer or sometimes no antimicrobial agents are effective against these bacteria. The Rio Grande River is the natural boundary between the United States (US) and Mexico. It spans a border region between Texas, New Mexico and Mexico. Underserved populations on the Mexican side use the river for recreational purposes, while on the US side, the river is used for irrigation and as a source of drinking water. OBJECTIVES: The purpose of the present study was to evaluate the concentration of antibiotic residues, to determine the presence of genetic elements conferring antibiotic resistance and to characterize multi-drug resistant bacteria in the waters of the Rio Grande River. METHODS: Water samples were obtained from the Rio Grande River. Deoxyribonucleic acid (DNA) was extracted from both isolated bacteria and directly from the water. Amplification of selected genetic elements was accomplished by polymerase chain reaction. Identification and isolation of bacteria was performed through MicroScan autoSCAN-4. Fecal contamination was assessed by IDEXX Colilert. Antibiotic residues were determined by liquid chromatography and mass spectrometry. RESULTS: Antibiotics were found in 92% of both water and sediment samples. Antibiotic concentrations ranged from 0.38 ng/L - 742.73 ng/L and 0.39 ng/l - 66.3 ng/g dry weight in water and sediment samples, respectively. Genetic elements conferring resistance were recovered from all collection sites. Of the isolated bacteria, 91 (64.08%) were resistant to at least two synergistic antibiotic combinations and 11 (14.79%) were found to be resistant to 20 or more individual antibiotics. Fecal contamination was higher during the months of April and July. CONCLUSIONS: The 26 km segment of the Rio Grande River from Sunland Park NM to El Paso, TX and Juarez, Mexico is an area of concern due to poor water quality. The presence of multidrug resistant bacteria, antibiotics and mobile genetic elements may be a health hazard for the surrounding populations of this binational border region. Policies need to be developed for the appropriate management of the environmental natural resources in this border region. COMPETING INTERESTS: The authors declare no competing financial interests.
ABSTRACT
BACKGROUND: El Paso, Texas and Ciudad Juarez, Mexico comprise the largest U.S./Mexico border population. METHODS: Bacterial samples were collected from two hospitals in El Paso and two in Ciudad Juarez and transported to a reference microbiology laboratory in El Paso for microbial identification and antimicrobial susceptibility testing according to NCCLS standards. The presence of the MecA gene, and the prevalence of both the SSCmec IV element and the Panton-Valentine leukocidin were investigated by PCR in all MRSA isolates. RESULTS: A total of 201 isolates in El Paso and 128 in Ciudad Juarez of Staphylococcus aureus were identified, of those, MRSA were significantly more prevalent in El Paso than in Ciudad Juarez [89 (44.3%) versus 10 (7.8%) respectively (p<0.0001)]. Thirty one (35%) of MRSA strains isolated in El Paso were community associated. CONCLUSION: Significantly higher prevalence of MRSA infections was documented in El Paso compared to Ciudad Juarez.