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Shigella and the fluorinated quinolones
1Department of Microbiology, Kasturba Medical College, Manipal.
Abstract:
Between July 1996 to June 1997 a total of 531 Stool samples from cases of acute diarrhoea, dysentry, colitis admitted to Kasturba Medical College Hospital, Manipal were investigated. Shigella were isolated from 29 samples (5.46%). Out of them, Shigella flexneri were 16 (55.17%), Shigella boydii 8 (27.58%), Shigella dysentriae 3 (10.34%) and Shigella sonnei 2 (6.89%). Five strains of Shigella flexneri and one strain of Shigella dysentriae were found to show resistance to Nalidixic acid and the newer fluoroquinolones viz., Ciprofloxacin, Norfloxacin and Ofloxacin. The in vitro 'R' factor transfer study showed that the resistance was not transferable.
Insights
Shigella bacteria were identified in 5.46% of stool samples from patients with acute diarrhea. Some Shigella strains exhibited resistance to nalidixic acid and fluoroquinolones, but this resistance was not transferable.
Area of Science:
- Microbiology
- Infectious Diseases
Background:
- Acute diarrhea, dysentery, and colitis are significant public health concerns.
- Shigella species are common causative agents of bacterial dysentery worldwide.
Purpose of the Study:
- To investigate the prevalence of Shigella in patients with acute gastrointestinal infections.
- To determine the antimicrobial susceptibility patterns of isolated Shigella strains, particularly to nalidixic acid and fluoroquinolones.
Main Methods:
- Analysis of 531 stool samples from patients admitted to Kasturba Medical College Hospital, Manipal, between July 1996 and June 1997.
- Isolation and identification of Shigella species using standard microbiological techniques.
- Antimicrobial susceptibility testing, including resistance to nalidixic acid and fluoroquinolones (Ciprofloxacin, Norfloxacin, Ofloxacin).
- In vitro 'R' factor transfer studies to assess the transmissibility of resistance.
Main Results:
- Shigella was isolated from 29 samples (5.46%).
- Shigella flexneri was the predominant species (55.17%), followed by Shigella boydii (27.58%), Shigella dysentriae (10.34%), and Shigella sonnei (6.89%).
- Six strains (five Shigella flexneri, one Shigella dysentriae) showed resistance to nalidixic acid and fluoroquinolones.
- In vitro studies indicated that the observed antimicrobial resistance was not transferable.
Conclusions:
- Shigella is an important cause of acute diarrheal diseases in the region studied.
- Emergence of resistance to nalidixic acid and fluoroquinolones in Shigella strains is a concern.
- The non-transferable nature of this resistance suggests chromosomal rather than plasmid-mediated mechanisms.