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Estimating the proportion of bystander selection for antibiotic resistance among potentially pathogenic bacterial flora.

ABSTRACT: Bystander selection-the selective pressure for resistance exerted by antibiotics on microbes that are not the target pathogen of treatment-is critical to understanding the total impact of broad-spectrum antibiotic use on pathogenic bacterial species that are often carried asymptomatically. However, to our knowledge, this effect has never been quantified. We quantify bystander selection for resistance for a range of clinically relevant antibiotic-species pairs as the proportion of all antibiotic exposures received by a species for conditions in which that species was not the causative pathogen ("proportion of bystander exposures"). Data sources include the 2010-2011 National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey, the Human Microbiome Project, and additional carriage and etiological data from existing literature. For outpatient prescribing in the United States, we find that this proportion over all included antibiotic classes is over 80% for eight of nine organisms of interest. Low proportions of bystander exposure are often associated with infrequent bacterial carriage or concentrated prescribing of a particular antibiotic for conditions caused by the species of interest. Applying our results, we roughly estimate that pneumococcal conjugate vaccination programs result in nearly the same proportional reduction in total antibiotic exposures of Streptococcus pneumoniae, Staphylococcus aureus, and Escherichia coli, despite the latter two organisms not being targeted by the vaccine. These results underscore the importance of considering antibiotic exposures of bystanders, in addition to the target pathogen, in measuring the impact of antibiotic resistance interventions.

SUBMITTER: Tedijanto C

PROVIDER: S-EPMC6304942 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Objectives:The objective of the present work was to examine the bacterial flora associated with the oral cavity of Indian cobra and to study their antibiogram. Methods:Oral swabs, collected from six healthy (4 males and 2 females) adult cobra, were subjected to microbiological examination through differential media. A total of 74 isolates which demonstrated noticeable colony characters were studied with different biochemical tests. The strains that showed distinctive colonies, morphology and biochemical parameters were additionally subjected to phylogenetic characterization using 16S rRNA gene sequences. Further, the isolates were subjected to antimicrobial susceptibility testing using ICOSA-20-plus and ICOSA-20-minus. Results:Microscopic examination of the oral cavity of Indian cobra revealed the dominance of Gram-negative bacteria over Gram-positive. The oral microflora constituted of bacteria such as Salmonella sp. (S. typhi, S. paratyphi A); Pseudomonas sp. (P. aeruginosa, P. fluorescence); Proteus sp. (P. mirabilis, P. penneri, P. vulgaris); E. coli; Morganella sp.; Citrobacter sp. (C. diversus, C. freundii); Aeromonas sp. (A. hydrophila, A. salmonicida); Enterobacter sp. (E. aerogens); Acinetobacter sp. (A. baumannii); Neisseria sp.; Serratia sp.; Bacillus sp. (B. cereus, B. megatarium, B. atrophaeus and B. weihenstephanensis); Enterococcus sp. (E. faecalis, E. faecium); Staphylococcus sp. (S. aureus, S. epidermidis); Alcaligenes sp.; Chryseobacterium sp. and Micrococcus sp. Most of the isolates were resistant towards antibiotics such as Penicillin, Cefpodoxime, Amoxyclav, Co-Trimoxazole, Ticarcillin, Erythromycin and Nalidixic acid while sensitive towards Ciprofloxacin, Gentamicin, Ofloxacin, Sparfloxacin, Tobromycin, Ceftriaxone, Tetracycline, Novobiocin and Imipenem. Conclusions:The secondary complications of the snake bite victims should be managed with appropriate antibiotics after proper examination of the bacterial flora from the wound sites.

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Estimating the proportion of bystander selection for antibiotic resistance among potentially pathogenic bacterial flora.

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