I. Gerchman's research while affiliated with Kimron Veterinary Institute and other places

Publications (27)

Article
Full-text available
The in vitro activity of enrofloxacin against 73 Mycoplasma synoviae field strains isolated in Israel and Europe was determined by broth microdilution. Decreased susceptibility to enrofloxacin was identified in 59% of strains, with the MICs ranging from 1 to >16 μg/ml. The estimated MIC50 and MIC90 values for enrofloxacin were 2 and 8 μg/ml, respec...
Article
Molecular characterization of the quinolone-resistance determining regions (QRDRs) of DNA gyrase and topoisomerase IV in 93 Mycoplasma gallisepticum field strains isolated in different geographic regions revealed discrepancies between minimal inhibitory concentration values and presence of amino acid substitutions within the QRDRs of GyrA and ParC...
Article
Monitoring of the susceptibility of Mycoplasma bovis field isolates to antibiotics is important for the appropriate choice of treatment. However, in vitro susceptibility testing of mycoplasmas is technically demanding and time-consuming, especially for clinical isolates, and is rarely performed in mycoplasma diagnostic laboratories. Thus, the devel...
Article
Full-text available
Comparison of the quinolone resistance-determining regions (QRDRs) in 42 Mycoplasma bovis clinical isolates revealed amino acid substitutions at both GyrA (position 83) and ParC (position 84) in 10/11 enrofloxacin-resistant strains. The mutation present in the parC QRDR was discriminative for enrofloxacin resistance by parC PCR-restriction fragment...
Article
Emergence of resistance to fluoroquinolones is mainly due to chromosomal mutations in genes encoding the subunits of the drug's target enzymes, DNA gyrase and topoisomerase IV, which are essential for DNA replication. The quinolone resistance-determining regions (QRDRs) of these genes were characterized in 25 Mycoplasma gallisepticum strains isolat...
Article
Monitoring of susceptibility to antibiotics in field isolates of pathogenic avian mycoplasmas is important for appropriate choice of treatment. Our study compared in vitro susceptibility to enrofloxacin and difloxacin in recent (2005-2006) isolates of Mycoplasma gallisepticum and Mycoplasma synoviae from meat-type turkey flocks with archived (1997-...
Article
Full-text available
This work reports the development of a 16S rRNA-based polymerase chain reaction (PCR) test for the detection of Mycoplasma meleagridis, and the application, together with a previously described multi-species PCR, for the diagnosis of M. meleagridis and M. iowae in dead-in-shell turkey embryos. Forty-six allantoic fluid samples from dead-in-shell tu...

Citations

... The quinolone resistance mechanisms have been illustrated in many Mycoplasma spp., such as M. agalactiae [13], M. gallisepticum [14], M. synoviae [15], M. hyopneumoniae [16] and M. bovis [17]. However, the quinolone resistance mechanism in M. hyorhinis was still unknown. ...
... QRDRs were amplified using gene-specific primers designed from the genomic sequence of M. gallisepticum strain R (accession no. AE015450), which included gyrA-F5'-GAGCTA-GAAACATCATTCATGG-3' and gyrA-R 5'-CCTA-CAGCAATACCACTT GAA-3' for the gyrA gene, and parC-F 5'-GATCTTGATGATATATCGTCAC-3' and parC-F 5'-CCAGTTGAACCATTAACGAGT-3' for the parC gene (14). PCR reactions were performed in a total volume of 50 μl containing 1× GoTaq ® Green Master Mix (Promega ® , Madison, WI, USA), 800 nM of each primer; and 100 ng/5μL of positive mycoplasma sample were used as DNA template. ...
... The method is not applicable on all the antimicrobials and is highly dependent on the PCR machine used. In addition, some initiatives for other PCR methods (Taqman SNP real-time PCR assay) have been published but never adopted by the diagnosis community [115]. ...
... Previous research showed that there was a base mutation in 16S rRNA, but no base mutation was detected in S12 ribosomal protein (15)(16)(17). Amino acid mutations at the quinolone resistance-determining region (QRDR) in gyrA, gyrB, parC, and parE conferred resistance to fluoroquinolones (18). The mutation in the QRDR of gyrA contributed to nalidixic acid resistance (19). ...
... However, Ser-83→Ile mutation has been correlated with fluoroquinolone-resistant mutants of M. gallisepticum, which showed increased MIC in vitro (22). Substitutions at position 83 in GyrA were highly variable (e.g., Ser-83→Leu/Trp/Phe/Tyr/Asn/ Arg), where some mutations caused greater increases in resistance than other substitutions in different bacteria and mycoplasmas due to structural differences between amino acids (23,24,25). Table 1). ...
... Mycoplasma iowae (and particularly field strains) do not tolerate some culture media and it has been shown that direct plating methods on agar can be more favoured than broth inoculation . Culture had been used as the primary diagnostic tool until the development of a number of field-strain validated PCR assays (Garcia et al., 1997;Cai et al., 2008). Culture remains a viable and important diagnostic method and is significantly less expensive than PCR. ...
... Mg isolates collected in different geographical locations before 1997 showed low MIC50 (0.05 µg/mL) and MIC90 (0.1 µg/mL) values for enrofloxacin [40]. In Israel, the Mg isolates collected between 1997 and 2003 showed enrofloxacin MIC values ≤0.5 µg/mL, whereas a marked decrease in susceptibility was recorded in 2005-2006 [41]. During another Israeli study, 79% of the strains isolated between 2006 and 2010 revealed to be resistant to enrofloxacin [42]. ...