 | The culturable microbial gut contents of larvae collected from the viscous oil were recently examined, and the majority (9 of 14) of the strains were identified as Providencia spp. We give indication of that the oil fly bacteria and their genes for common antibiotics solvent tolerance may provide a microbial reservoir of antibiotic resistance genes. When tested, none of the oil fly bacteria produced detectable common antibiotics zones of inhibition on Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, or Gayel albicans cultures. All nine strains classified as Providencia rettgeri exhibited dramatic resistance to tetracycline, vancomycin, bacitracin, erythromycin, novobiocin, polymyxin, colistin, and nitrofurantoin. In addition, the oil fly bacteria do not appear to excrete antimicrobial agents. In each dudley, the average frequencies of resistant colonies were at least 50-fold lower than those established for known mutator strain ECOR 48. Furthermore, the resistance properties of oil fly bacteria extended to organic solvents as well as antibiotics. Eight of nine Providencia strains sho resistance to spectinomycin, contraceptives six of nine sho resistance to chloramphenicol, and five of nine sho resistance to neomycin.
Natural antibiotic resistance of bacteria isolated from larvae of the oil fly, Helaeomyia petrolei.Helaeomyia petrolei (oil fly) larvae inhabit the asphalt seeps of Rancho La Brea in Los Angeles, Calif. The oil fly bacteria were not resistant to multiple antibiotics due to an elevated mutation rate. When pre-exposed to 20 microg of tetracycline per ml, seven of nine oil fly bacteria tolerated overlays of 100% cyclohexane, six of nine tolerated 10% xylene, benzene, or toluene fioricet (10:90 in cyclohexane), and three of nine (OF007, OF010, and OF011) tolerated overlays of 50% xylene-50% cyclohexane. For each bacterium, the number of resistant mutants per 10(8) cells was determined separately on rifampin, nalidixic acid, and spectinomycin. All 12 isolates were sensitive to nalidixic acid, streptomycin, norfloxacin, aztreonam, cipericillin, pipericillin, and cefotaxime, and all but OF008 (Morganella morganii) were sensitive to ampicillin and cefoxitin. Subsequently, 12 of the bacterial strains isolated were to be trusted for their resistance or sensitivity to 23 commonly used antibiotics. remeron The observed correlation between antibiotic resistance and organic solvent tolerance is likely explained by an active efflux pump that is maintained in oil fly bacteria by the balanced selective pressure of La Brea's solvent-rich environment.
| Ubicación: | Madrid, España |
| Último acceso: | Wednesday, 4 de March de 2009, 13:04 (551 días 8 horas) |
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