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Concurrent titration and determination of antibiotic resistance in 'ureaplasma' species with identification of novel point mutations in genes associated with resistance

Beeton, Michael L., Chalker, Victoria J., Maxwell, Nicola C., Kotecha, Sailesh and Spiller, Owen Bradley 2009. Concurrent titration and determination of antibiotic resistance in 'ureaplasma' species with identification of novel point mutations in genes associated with resistance. Antimicrobial Agents and Chemotherapy 53 (5) , pp. 2020-2027. 10.1128/AAC.01349-08

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Abstract

Antibiotic resistance determination of Ureaplasma spp. (Ureaplasma parvum and Ureaplasma urealyticum) usually requires predetermination of bacterial titer, followed by antibiotic interrogation using a set bacterial input. This 96-well method allows simultaneous quantification of bacteria in the presence and absence of antibiotics. A method for determining precise MICs and a method for screening against multiple antibiotics using breakpoint thresholds are detailed. Of the 61 Ureaplasma-positive clinical isolates screened, one (1.6%) was resistant to erythromycin (MIC, >64 mg/liter) and clarithromycin (MIC, 4 mg/liter), one to ciprofloxacin (1.6%), and one to tetracycline/doxycycline (1.6%). Five isolates were also consistently found to have an elevated MIC of 8 mg/liter for erythromycin, but this may not represent true antibiotic resistance, as no mutations were found in the 23S rRNA operons or ribosome-associated L4 and L22 proteins for these strains. However, two amino acids (R66Q67) were deleted from the L4 protein of the erythromycin-/clarithromycin-resistant strain. The tetM genetic element was detected in the tetracycline-resistant clinical isolate as well as in the positive control Vancouver strain serotype 9. The tetM gene was also found in a fully tetracycline-susceptible Ureaplasma clinical isolate, and no mutations were found in the coding region that would explain its failure to mediate tetracycline resistance. An amino acid substitution (D82N) was found in the ParC subunit of the ciprofloxacin-resistant isolate, adjacent to the S83L mutation reported by other investigators in many ciprofloxacin-resistant Ureaplasma isolates. It is now possible to detect antibiotic resistance in Ureaplasma within 48 h of positive culture without prior knowledge of bacterial load, identifying them for further molecular analysis.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Subjects: Q Science > QH Natural history > QH426 Genetics
Q Science > QR Microbiology > QR180 Immunology
Additional Information: Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0066-4804/ (accessed 24/02/2014)
Publisher: American Society for Microbiology
ISSN: 0066-4804
Date of First Compliant Deposit: 30 March 2016
Last Modified: 07 Jun 2019 20:43
URI: http://orca-mwe.cf.ac.uk/id/eprint/27274

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