Alarmingly High Segregation Frequencies of Quinolone Resistance Alleles within Human and Animal Microbiomes Are Not Explained by Direct Clinical Antibiotic Exposure.
Bottom Line: Within host-associated environments, resistance to quinolones was most often conferred by a specific resistance allele.High frequencies of quinolone resistance alleles were also found within hosts that were not directly treated with antibiotics.Therefore, the high segregation frequency of quinolone resistance alleles occurring within the housekeeping targets of antibiotics in host-associated environments does not seem to be the sole result of clinical antibiotic usage.
Affiliation: Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, the Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.Show MeSH
Mentions: We already showed that quinolone TRA frequencies were quite high, even in hosts that were not expected to be clinically exposed to antibiotics (i.e., the tropical pheasant Hoatzin, for which ∼43% of GyrA/ParC sequences carried a TRA). To further demonstrate that frequencies of TRAs can be quite high within hosts—even in the absence of clinical antibiotic exposure—we focused on gut samples from humans we know were not clinically treated recently or at all with quinolones and the remaining antibiotic classes on which we focused in this study. Vallés et al. sequenced gut metagenomic samples from mother–infant pairs. The mothers were sampled before and after giving birth, and the infants were sampled along five time points of development during the first year following their birth. Antibiotic usage was documented for both the mothers and the infants. For this reason, we know that the mothers were not treated with our antibiotics of interest for at least 3 months prior to giving birth and that the children were never directly treated with these antibiotics. Although, these metagenomic samples were not directly exposed to antibiotics in clinical dosages, we found a relatively high frequency of quinolone TRAs within both mothers and children (ranging from 12.16% to 33.65% with an average of 22.56%, fig. 5). Quinolone TRA frequencies within the mothers and the oldest children match very well the frequency of TRAs we observed in the human gut samples extracted from IMG/M (fig. 5).Fig. 5.—
Affiliation: Rachel & Menachem Mendelovitch Evolutionary Processes of Mutation & Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, the Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.