Is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with SalmonellaTyphi?
Introduction: Considering the limitations of screening with nalidixic acid to detect reduced susceptibility to fluoroquinolones of Salmonella enterica serovar Typhi (S.Typhi) strains, we evaluated the use of a 30 µg nalidixic acid disc screening method in Pakistan. Methodology: Non duplicate nalidi...
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The Journal of Infection in Developing Countries
2012-10-01
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| Series: | Journal of Infection in Developing Countries |
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| Online Access: | https://jidc.org/index.php/journal/article/view/1910 |
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| author | Seema Irfan Kausar Jabeen Umair Anwar Jilani Bushra Ahmed Jaishri Mehraj Tanwir Ahsan Afia Zafar |
| author_facet | Seema Irfan Kausar Jabeen Umair Anwar Jilani Bushra Ahmed Jaishri Mehraj Tanwir Ahsan Afia Zafar |
| author_sort | Seema Irfan |
| collection | DOAJ |
| description | Introduction: Considering the limitations of screening with nalidixic acid to detect reduced susceptibility to fluoroquinolones of Salmonella enterica serovar Typhi (S.Typhi) strains, we evaluated the use of a 30 µg nalidixic acid disc screening method in Pakistan.
Methodology: Non duplicate nalidixic acid susceptible S. Typhi isolates (246) from 2003-2008 were retrieved from the Salmonella strain bank. Minimum inhibitory concentrations of ciprofloxacin for all strains were determined by agar dilution and further rechecked by ciprofloxacin E-tests.E. coli ATCC 25922 was used as the control strain. The MIC data for ciprofloxacin were compared with nalidixic acid disk (30µg) zone diameters.
Results: Repeat testing of all S. Typhi isolates with a nalidixic acid (30µg) disk showed 100% susceptibility with an average zone diameter of 26 mm. Agar dilution testing revealed reduced susceptibility to ciprofloxacin, with MICs of 0.125 µg /ml for three (1.2%) isolates only. Zone sizes of strains with higher MICs were significantly lower than the strains with lower MICs (20 versus 26 mm) (p value < 0.001).
Conclusion: Estimation of fluoroquinolone MICs on every nalidixic acid susceptible S. Typhi strain is not cost effective in our setting; the proportion of strains with high fluoroquinolone MICs was found to be very low. We recommend periodic fluoroquinolone MIC determination to include all isolates with a nalidixic acid borderline zone (size 20-22 mm).
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| format | Article |
| id | doaj-art-e301e78dce634b77b7af8480cfca395b |
| institution | OA Journals |
| issn | 1972-2680 |
| language | English |
| publishDate | 2012-10-01 |
| publisher | The Journal of Infection in Developing Countries |
| record_format | Article |
| series | Journal of Infection in Developing Countries |
| spelling | doaj-art-e301e78dce634b77b7af8480cfca395b2025-08-20T02:14:19ZengThe Journal of Infection in Developing CountriesJournal of Infection in Developing Countries1972-26802012-10-0161010.3855/jidc.1910Is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with SalmonellaTyphi?Seema Irfan0Kausar Jabeen1Umair Anwar Jilani2Bushra Ahmed3Jaishri Mehraj4Tanwir Ahsan5Afia Zafar6Aga Khan University, Karachi, PakistanAga Khan University, Karachi, PakistanAga Khan University, Karachi, PakistanAga Khan University, Karachi, PakistanAga Khan University, Karachi, PakistanAga Khan University, Karachi, PakistanAga Khan University, Karachi, PakistanIntroduction: Considering the limitations of screening with nalidixic acid to detect reduced susceptibility to fluoroquinolones of Salmonella enterica serovar Typhi (S.Typhi) strains, we evaluated the use of a 30 µg nalidixic acid disc screening method in Pakistan. Methodology: Non duplicate nalidixic acid susceptible S. Typhi isolates (246) from 2003-2008 were retrieved from the Salmonella strain bank. Minimum inhibitory concentrations of ciprofloxacin for all strains were determined by agar dilution and further rechecked by ciprofloxacin E-tests.E. coli ATCC 25922 was used as the control strain. The MIC data for ciprofloxacin were compared with nalidixic acid disk (30µg) zone diameters. Results: Repeat testing of all S. Typhi isolates with a nalidixic acid (30µg) disk showed 100% susceptibility with an average zone diameter of 26 mm. Agar dilution testing revealed reduced susceptibility to ciprofloxacin, with MICs of 0.125 µg /ml for three (1.2%) isolates only. Zone sizes of strains with higher MICs were significantly lower than the strains with lower MICs (20 versus 26 mm) (p value < 0.001). Conclusion: Estimation of fluoroquinolone MICs on every nalidixic acid susceptible S. Typhi strain is not cost effective in our setting; the proportion of strains with high fluoroquinolone MICs was found to be very low. We recommend periodic fluoroquinolone MIC determination to include all isolates with a nalidixic acid borderline zone (size 20-22 mm). https://jidc.org/index.php/journal/article/view/1910enteric feverantimicrobial resistancenalidixic acid susceptiblefluoroquinolone resistant |
| spellingShingle | Seema Irfan Kausar Jabeen Umair Anwar Jilani Bushra Ahmed Jaishri Mehraj Tanwir Ahsan Afia Zafar Is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with SalmonellaTyphi? Journal of Infection in Developing Countries enteric fever antimicrobial resistance nalidixic acid susceptible fluoroquinolone resistant |
| title | Is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with SalmonellaTyphi? |
| title_full | Is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with SalmonellaTyphi? |
| title_fullStr | Is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with SalmonellaTyphi? |
| title_full_unstemmed | Is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with SalmonellaTyphi? |
| title_short | Is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with SalmonellaTyphi? |
| title_sort | is nalidixic acid screening still valid for the detection of reduced susceptibility of fluoroquinolone with salmonellatyphi |
| topic | enteric fever antimicrobial resistance nalidixic acid susceptible fluoroquinolone resistant |
| url | https://jidc.org/index.php/journal/article/view/1910 |
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