Molecular characterization of multidrug-resistant Shigella species isolated from epidemic and endemic cases of shigellosis in India

Abstract

Shigella species represent one of the growing numbers of antimicrobial-resistant bacteria in developing countries. Fluoroquinolone-resistant strains of Shigella dysenteriae type1 and Shigella flexneri type 2a emerged in India during 2002 and 2003, respectively. Sixty strains of Shigella from different parts of India were analysed for antimicrobial susceptibility, the presence of the qnr plasmid, mutations in the quinolone resistance determining regions (QRDRs), fluoroquinolone accumulation, and the presence of other genes encoding resistance to various antimicrobials. Fluoroquinolone-resistant strains had mutations in gyrA and parC genes and had an active efflux system. They were also resistant to several other antimicrobials but were susceptible to azithromycin and ceftriaxone. The majority of the strains harboured genes encoding resistance to ampicillin (97 %), tetracycline (95 %), streptomycin (95 %) and chloramphenicol (94 %). PFGE analysis revealed clonality among strains of S. dysenteriae types 1 and 5, S. flexneri type 2a and Shigella boydii type 12. INTRODUCTIONShigellosis remains an important public health problem in developing countries with Shigella sonnei in Europe and the US and Shigella flexneri in Asian and African countries being of epidemiological importance. Antimicrobial therapy is advocated for shigellosis to shorten the duration of illness (Salam & Bennish, 1991). However, in Asia and Africa, antimicrobial resistance is an emerging problem among Shigella species (von Seidlein et al., 2006) and treatment options are becoming limited globally (Salam & Bennish, 1991;Kariuki & Hart, 2001). The World Health Organization has recommended that ciprofloxacin should be considered a first-line antibiotic for the treatment of shigellosis, and the use of nalidixic acid is not encouraged, even in areas where it is still effective against Shigella (WHO, 2004). Similar to the prevalence of different serotypes, antimicrobial-resistance patterns of strains also differ from country to country and even within the same country (Pazhani et al., 2005;von Seidlein et al., 2006), which may be due to the spread of resistant clones as found for multidrug-resistant strains of Shigella dysenteriae type 1 in eastern parts of India (Pazhani et al., 2004). In this study, we have investigated the mechanisms of antibiotic resistance and clonal relatedness of Shigella strains isolated from epidemic and endemic cases of shigellosis in different parts of India. METHODSBacterial strains. We examined 60 strains of Shigella species (20 S. dysenteriae, 16 S. flexneri, 7 Shigella boydii and 17 S. sonnei) isolated from dysentery outbreaks from different parts of India and sporadic hospitalized cases of shigellosis in Kolkata and Goa between 2001 and 2004. Strains were confirmed as Shigella spp. by standard biochemical tests (WHO, 1987) and serotyped using commercially available antisera (Denka Seiken).Antimicrobial susceptibility testing. Antimicrobial susceptibility tests were performed by a disc diffusion method in accordance with...

The Recent Trends of Shigellosis: A JIPMER Perspective

“…The Shigella species usually harbour a heterogeneous population of plasmids which range in numbers from 2 to as many as 10 [16]. The ability of these organisms to acquire the resistance genes which are located on the mobile elements, the continuous selective pressure which results from the high levels of the antibiotic consumption and the presence of the poor quality unlicensed antibacterial agents in some areas, enhances the likelihood of the development of resistance [2,[7][8][9]13,14]. The molecular characterization of the strains is underway, which will throw more light on the details of the drug resistance.…”

“…Conventionally, the fluoroquinolones have been the mainstay of the treatment for Shigellosis. With the emergence of fluoroquinolone resistance among the Shigellae [2][3][4][5][6][7], the choice of the antibiotics has been reduced further.…”

Pulsed-Field Gel Electrophoresis (PFGE) standardization protocol for Proteus mirabilis

“…PFGE yöntemi agaroz içine gömülü haldeki bakteriden, yapısal bütünlüğü bozulmadan izole edilen kromozomun, restriksiyon enzimi (RE) ile kesim profilinin belirlenmesi esasına dayanır [18,19,20]. Yöntemde başlıca şu aşamalar bulunmaktadır: çalışılacak bakterilerin hazırlanması, bakterilerin agarozla karıştırılması, agaroz içindeki bakterilerin parçalanması (in situ lysis), agaroz içindeki kromozomun saflaştırılması, agaroz içindeki kromozomal DNA'nın RE ile kesilmesi (in situ-digestion), elektroforezle DNA parçalarının ayrıştırılması, DNA bantların görünür hale getirilmesi ve sonuçların yorumlanması [8,14,21].…”

Gallic acid conjugated with gold nanoparticles: antibacterial activity and mechanism of action on foodborne pathogens

“…7 At present, increasing antibiotic resistance of P. shigelloides implies that fewer antibiotic drugs can produce bactericidal minimum inhibitory concentration (MIC). 6,8,9 S. flexneri is highly infectious at low counts. 10 First-line antimicrobial drugs, including sulfonamides, tetracycline, ampicillin, and trimethoprim-sulfamethoxazole, have become ineffective due to plasmidencoded resistance to S. flexneri, which causes more than a million deaths worldwide.…”

“…4 Antibiotic treatment is required to reduce the severity of diarrhea or its duration. 5,6 P. shigelloides is sensitive to quinolones and cephalosporins. Owing to beta-lactam production, partial resistance to ampicillin, tetracycline, cotrimoxazole, and chloramphenicol has been reported (72%, 67%, 12%, and 5%, respectively).…”