TY  - JOUR
T1  - Laboratory Detection of <I>Haemophilus parasuis </I>with Decreased Susceptibility to Nalidixic Acid and Enrofloxacin Due to GyrA and ParC Mutations
AU - Chen, Pin AU - Liu, Yingyu AU - Liu, Chong AU - Zou, Haoyong AU - Wang, Yang AU - Li, Wentao AU - Bi, Dingren AU - He, Qigai 
JO  - Journal of Animal and Veterinary Advances
VL  - 10
IS  - 21
SP  - 2870
EP  - 2873
PY  - 2011
DA  - 2001/08/19
SN  - 1680-5593
DO  - javaa.2011.2870.2873
UR  - https://makhillpublications.co/view-article.php?doi=javaa.2011.2870.2873
KW  - Detection
KW  -enrofloxacin
KW  -resistance
KW  -collection
KW  -nalidixic acid
KW  -China
AB  - The detection of pathogens with decreased susceptibility to antibacterial and elucidating the molecular mechanism of resistance are of epidemiological and clinical interest in animal husbandry. The 21 <I>Haemophilus parasuis</I> clinical isolates and one American Type Culture Collection reference strains of <I>Actinobacillus pleuropneumoniae</I> (ATCC 27090) were screened for susceptibility to nalidixic acid and enrofloxacin by the microdilution methods. The nalidixic acid MICs for all of the isolates were &ge;2 &#956;g mL<SUP>-1</SUP> and the enrofloxacin MICs for isolates were &le;8 &#956;g mL<SUP>-1</SUP>. In addition, the Quinolone Resistance-Determining Regions (QRDRs) of gyrA and parC of all strains were sequenced. Strains for which nalidixic acid MICs were &le;4.0 &#956;g mL<SUP>-1</SUP> lacked modifications in the QRDRs of GyrA and ParC. In contrast, all strains for which nalidixic acid MICs were &ge;8 &#956;g mL<SUP>-1</SUP> exhibited one or more amino acid changes in GyrA and ParC. Mutations in GyrA is the major resistance mechanism of <I>Haemophilus parasuis</I> to nalidixic acid and enrofloxacin.
ER  -