title: Extended antimicrobial resistance screening of the dominant faecal Escherichia coli and of rare resistant clones.
abstract: Fifty faecal samples from healthy adults were grown on MacConkey agar and three pink colonies were subcultured, identified to species level and their antimicrobial susceptibility determined. Forty-seven samples yielded 141 isolates of Escherichia coli that were susceptible to most antimicrobials. Resistance was noted for ampicillin (30.5%), chloramphenicol (12.1%), tetracycline (23.4%), trimethoprim (24.8%) and co-trimoxazole (22.7%). A direct faecal plating method was used for extended resistance screening with E. coli as the indicator organism. Zone breakpoints were determined using normalised resistance interpretation and gave similar susceptibility results. Eighty-eight isolates of E. coli from within the zones of inhibition revealed four times more antimicrobial resistance. Extended antimicrobial resistance screening both provides the susceptibility profile of the dominant E. coli isolate and detects greater resistance in rare isolates.
authors.affiliation: Clinical Microbiology - MTC, Karolinska Institute, Karolinska Hospital L2:02, SE-17176 Stockholm, Sweden. goran.kronvall@labmed.ki.se
authors.forename: Göran
authors.initials: G
authors.lastname: Kronvall
authors.forename: Mattias
authors.initials: M
authors.lastname: Larsson
authors.forename: Charlotte
authors.initials: C
authors.lastname: Borén
authors.forename: Gunnar
authors.initials: G
authors.lastname: Kahlmeter
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bartoloni
authors.forename: Gian Maria
authors.initials: GM
authors.lastname: Rossolini
authors.forename: Malin
authors.initials: M
authors.lastname: Grape
authors.forename: Charlotte
authors.initials: C
authors.lastname: Kristiansson
authors.forename: Inga
authors.initials: I
authors.lastname: Karlsson
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002353:Carrier State; D002701:Chloramphenicol / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D005493:Folic Acid Antagonists / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D013752:Tetracycline / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D005493:Folic Acid Antagonists; D002701:Chloramphenicol; D000667:Ampicillin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D014295:Trimethoprim; D013752:Tetracycline