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Antimicrobial resistance characteristics and fitness of Gram-negative fecal bacteria from volunteers treated with minocycline or amoxicillin.

Kirchner M, Mafura M, Hunt T, Abu-Oun M, Nunez-Garcia J, Hu Y, Weile J, Coates A, Card R, Anjum MF - Front Microbiol (2014)

Bottom Line: A yearlong study was performed to examine the effect of antibiotic administration on the bacterial gut flora.Following amoxicillin administration, an increase in the proportion of amoxicillin resistant E. coli and a three-fold increase in the levels of bla TEM gene carriage was observed, an effect not observed in the other two treatment groups.Although there were no unique characteristics associated with plasmids from persistent or transient isolates, PM assays showed transient isolates had greater adaptability to a range of antiseptic biocides and tetracycline; characteristics which were lost in some, but not all persistent isolates.

View Article: PubMed Central - PubMed

Affiliation: Department of Bacteriology, Animal and Plant Health Agency Addlestone, UK.

ABSTRACT
A yearlong study was performed to examine the effect of antibiotic administration on the bacterial gut flora. Gram-negative facultative anaerobic bacteria were recovered from the feces of healthy adult volunteers administered amoxicillin, minocycline or placebo, and changes determined in antimicrobial resistance (AMR) gene carriage. Seventy percent of the 1039 facultative anaerobic isolates recovered were identified by MALDI-TOF as Escherichia coli. A microarray used to determine virulence and resistance gene carriage demonstrated that AMR genes were widespread in all administration groups, with the most common resistance genes being bla TEM, dfr, strB, tet(A), and tet(B). Following amoxicillin administration, an increase in the proportion of amoxicillin resistant E. coli and a three-fold increase in the levels of bla TEM gene carriage was observed, an effect not observed in the other two treatment groups. Detection of virulence genes, including stx1A, indicated not all E. coli were innocuous commensals. Approximately 150 E. coli collected from 6 participants were selected for pulse field gel electrophoresis (PFGE), and a subset used for characterisation of plasmids and Phenotypic Microarrays (PM). PFGE indicated some E. coli clones had persisted in volunteers for up to 1 year, while others were transient. Although there were no unique characteristics associated with plasmids from persistent or transient isolates, PM assays showed transient isolates had greater adaptability to a range of antiseptic biocides and tetracycline; characteristics which were lost in some, but not all persistent isolates. This study indicates healthy individuals carry bacteria harboring resistance to a variety of antibiotics and biocides in their intestinal tract. Antibiotic administration can have a temporary effect of selecting bacteria, showing co-resistance to multiple antibiotics, some of which can persist within the gut for up to 1 year.

No MeSH data available.


Related in: MedlinePlus

Dendrogram showing the Biolog results for 14 selected isolates representing transient and persistent isolates. Each experiment was repeated in duplicate and both replicates are represented individually in the figure. The two groups generated by comparing the respiration profiles of the isolates are indicated. The Hierarchical clustering was used to generate a dendrogram using R-conductor program (http://www.bioconductor.org/). The sample ID is defined as such: first T or P indicating if a strain is transient or persistent, the second letter (A, M, P) indicates which treatment was administered and the final ARD reference is the isolate number.
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Figure 4: Dendrogram showing the Biolog results for 14 selected isolates representing transient and persistent isolates. Each experiment was repeated in duplicate and both replicates are represented individually in the figure. The two groups generated by comparing the respiration profiles of the isolates are indicated. The Hierarchical clustering was used to generate a dendrogram using R-conductor program (http://www.bioconductor.org/). The sample ID is defined as such: first T or P indicating if a strain is transient or persistent, the second letter (A, M, P) indicates which treatment was administered and the final ARD reference is the isolate number.

Mentions: Biolog phenotype microarrays were utilized to determine whether there were conditions which could help explain why some isolates were transient and others persistent, and if there was an effect of antibiotic administration. The 14 isolates selected above were exposed to different stress modulators and their ability to respire in the conditions measured (Supplementary Table 2). A hierarchical clustering was performed on the results of respiration (AUC values) of isolates using compounds present on all 10 plates (Figure 4). In general, technical replicates showed high similarity, but it was not possible to distinguish between isolates from the minocycline, amoxicillin, and placebo groups using this phenotypic method. However two groups of isolates were detected by hierarchical clustering; group 1 contained 4 isolates and group 2 contained 10 isolates. All seven transient isolates grouped within group 2, while persistent isolates were divided between groups 1 and 2 (Figure 4). A principal component analysis (PCA) was also performed on the results of respiration (AUC values) and identified the same two groups shown in Figure 4 (data not shown). Isolates in each group did not represent any single ST type or complex. Several compounds were identified in which all or most isolates within group 2 were able to respire (Table 2). These included several antiseptic biocidal agents such as domiphen bromide and alexidine, and two compounds which are known to modulate efflux mechanisms, chlorpromazine and promethazine (Table 2). Surprisingly, all isolates from group 2 showed the presence of tetracycline resistance genes by array (Table 1), which were absent from all group 1 isolates; as a result differential respiration rates were observed between group 1 and group 2 for several tetracycline derivatives (Table 2).


Antimicrobial resistance characteristics and fitness of Gram-negative fecal bacteria from volunteers treated with minocycline or amoxicillin.

Kirchner M, Mafura M, Hunt T, Abu-Oun M, Nunez-Garcia J, Hu Y, Weile J, Coates A, Card R, Anjum MF - Front Microbiol (2014)

Dendrogram showing the Biolog results for 14 selected isolates representing transient and persistent isolates. Each experiment was repeated in duplicate and both replicates are represented individually in the figure. The two groups generated by comparing the respiration profiles of the isolates are indicated. The Hierarchical clustering was used to generate a dendrogram using R-conductor program (http://www.bioconductor.org/). The sample ID is defined as such: first T or P indicating if a strain is transient or persistent, the second letter (A, M, P) indicates which treatment was administered and the final ARD reference is the isolate number.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4269195&req=5

Figure 4: Dendrogram showing the Biolog results for 14 selected isolates representing transient and persistent isolates. Each experiment was repeated in duplicate and both replicates are represented individually in the figure. The two groups generated by comparing the respiration profiles of the isolates are indicated. The Hierarchical clustering was used to generate a dendrogram using R-conductor program (http://www.bioconductor.org/). The sample ID is defined as such: first T or P indicating if a strain is transient or persistent, the second letter (A, M, P) indicates which treatment was administered and the final ARD reference is the isolate number.
Mentions: Biolog phenotype microarrays were utilized to determine whether there were conditions which could help explain why some isolates were transient and others persistent, and if there was an effect of antibiotic administration. The 14 isolates selected above were exposed to different stress modulators and their ability to respire in the conditions measured (Supplementary Table 2). A hierarchical clustering was performed on the results of respiration (AUC values) of isolates using compounds present on all 10 plates (Figure 4). In general, technical replicates showed high similarity, but it was not possible to distinguish between isolates from the minocycline, amoxicillin, and placebo groups using this phenotypic method. However two groups of isolates were detected by hierarchical clustering; group 1 contained 4 isolates and group 2 contained 10 isolates. All seven transient isolates grouped within group 2, while persistent isolates were divided between groups 1 and 2 (Figure 4). A principal component analysis (PCA) was also performed on the results of respiration (AUC values) and identified the same two groups shown in Figure 4 (data not shown). Isolates in each group did not represent any single ST type or complex. Several compounds were identified in which all or most isolates within group 2 were able to respire (Table 2). These included several antiseptic biocidal agents such as domiphen bromide and alexidine, and two compounds which are known to modulate efflux mechanisms, chlorpromazine and promethazine (Table 2). Surprisingly, all isolates from group 2 showed the presence of tetracycline resistance genes by array (Table 1), which were absent from all group 1 isolates; as a result differential respiration rates were observed between group 1 and group 2 for several tetracycline derivatives (Table 2).

Bottom Line: A yearlong study was performed to examine the effect of antibiotic administration on the bacterial gut flora.Following amoxicillin administration, an increase in the proportion of amoxicillin resistant E. coli and a three-fold increase in the levels of bla TEM gene carriage was observed, an effect not observed in the other two treatment groups.Although there were no unique characteristics associated with plasmids from persistent or transient isolates, PM assays showed transient isolates had greater adaptability to a range of antiseptic biocides and tetracycline; characteristics which were lost in some, but not all persistent isolates.

View Article: PubMed Central - PubMed

Affiliation: Department of Bacteriology, Animal and Plant Health Agency Addlestone, UK.

ABSTRACT
A yearlong study was performed to examine the effect of antibiotic administration on the bacterial gut flora. Gram-negative facultative anaerobic bacteria were recovered from the feces of healthy adult volunteers administered amoxicillin, minocycline or placebo, and changes determined in antimicrobial resistance (AMR) gene carriage. Seventy percent of the 1039 facultative anaerobic isolates recovered were identified by MALDI-TOF as Escherichia coli. A microarray used to determine virulence and resistance gene carriage demonstrated that AMR genes were widespread in all administration groups, with the most common resistance genes being bla TEM, dfr, strB, tet(A), and tet(B). Following amoxicillin administration, an increase in the proportion of amoxicillin resistant E. coli and a three-fold increase in the levels of bla TEM gene carriage was observed, an effect not observed in the other two treatment groups. Detection of virulence genes, including stx1A, indicated not all E. coli were innocuous commensals. Approximately 150 E. coli collected from 6 participants were selected for pulse field gel electrophoresis (PFGE), and a subset used for characterisation of plasmids and Phenotypic Microarrays (PM). PFGE indicated some E. coli clones had persisted in volunteers for up to 1 year, while others were transient. Although there were no unique characteristics associated with plasmids from persistent or transient isolates, PM assays showed transient isolates had greater adaptability to a range of antiseptic biocides and tetracycline; characteristics which were lost in some, but not all persistent isolates. This study indicates healthy individuals carry bacteria harboring resistance to a variety of antibiotics and biocides in their intestinal tract. Antibiotic administration can have a temporary effect of selecting bacteria, showing co-resistance to multiple antibiotics, some of which can persist within the gut for up to 1 year.

No MeSH data available.


Related in: MedlinePlus