Year : 2015 | Volume
: 58 | Issue : 1 | Page : 113--114
A case of extended spectrum beta-lactamase producing Salmonella enterica serotype paratyphi A from India
Priyamvada Roy, Deepti Rawat, Sonia Malik
Department of Microbiology, Maulana Azad Medical College, Delhi, India
Dr. Sonia Malik
Department of Microbiology, Maulana Azad Medical College, Delhi
Enteric fever caused by Salmonella enterica is a systemic infection with high rates of morbidity and mortality. Increasing antibiotic resistance in S. enterica has led to shift in the choice of antibiotics used against this organism from chloramphenicol and ampicillin to trimethoprim-sulfamethoxazole, fluoroquinolones, and extended-spectrum cephalosporins. Resistance to cephalosporins, due to the production of extended-spectrum beta-lactamases (ESBLs), is the cause of serious concern worldwide. So far, these enzymes have been detected in many species of the family Enterobacteriaceae including different serotypes of S. enterica. To the best of our knowledge, however, ESBL production in Salmonella Paratyphi A has not yet been reported from India. We present here a case of ESBL producing Salmonella Paratyphi A from India. This is a worrisome finding with grave clinical implications, since the dissemination of this resistance trait would further limit the therapeutic options available for the treatment of enteric fever.
|How to cite this article:|
Roy P, Rawat D, Malik S. A case of extended spectrum beta-lactamase producing Salmonella enterica serotype paratyphi A from India.Indian J Pathol Microbiol 2015;58:113-114
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Roy P, Rawat D, Malik S. A case of extended spectrum beta-lactamase producing Salmonella enterica serotype paratyphi A from India. Indian J Pathol Microbiol [serial online] 2015 [cited 2021 Apr 18 ];58:113-114
Available from: https://www.ijpmonline.org/text.asp?2015/58/1/113/151205
Enteric fever, including typhoid fever caused by Salmonella enterica subspecies enterica serotype typhi (Salmonella Typhi) and paratyphoid fever caused by S. enterica subspecies enterica serotype paratyphi A (Salmonella Paratyphi A), is one of the most important febrile illnesses in tropical and subtropical countries, with high rates of morbidity and mortality.  In potentially life-threatening cases, the antibiotics of choice are fluoroquinolones and extended-spectrum cephalosporins.  The emergence of drug resistance in Salmonella Typhi and Salmonella Paratyphi A is an emerging public health problem.  Owing to the recent increase of fluoroquinolone resistance, third-generation cephalosporins have become the primary drugs for the treatment of enteric fever.  Recently, extended-spectrum beta-lactamase (ESBL) producing strains of Salmonella Paratyphi A that are resistant to third-generation cephalosporins have been reported from several countries, but not from India. ,, Here, we present the first case-report of ESBL producing Salmonella Paratyphi A from India.
An 11-year-old boy, a resident of Delhi, presented with complaints of continuous high-grade fever with step-ladder rise of temperature, headache, and malaise, for 5 days. There were no toxic symptoms, diarrhea, abdominal pain, hepatomegaly, splenomegaly, or spots on the skin. The patient had been undergoing treatment with oral cefpodoxime proxetil 100 mg twice daily for 3 days before testing, with no improvement in his condition. There was no recent history of any prolonged illness, hospitalization, previous intake of antibiotics, or similar illness in the family. There was a history of vaccination with Vi capsular polysaccharide vaccine at the age of 5 years. His hematocrit parameters showed total leukocyte count within limit (5100/μl) but on the lower side of the normal range (4000-11000/μl) with few activated lymphocytes. The red blood cells were normocytic and normochromic. His blood film was negative for malarial parasite. His blood sample for culture was collected aseptically and processed in BACTEC 9050 (Becton Dickinson Biosciences). Positive signal was detected after 24 h of incubation, following which it was subcultured on blood agar and MacConkey agar. After overnight incubation at 37°C, blood agar showed nonpigmented (grey-white) colonies of size 1-2 mm, opaque, nonhemolytic, moist, circular with a smooth convex surface and the entire edge. The growth on MacConkey agar consisted of nonlactose fermenting colonies of similar morphology. Colonies were catalase positive and oxidase negative. Gram-stained smear from the growth revealed Gram-negative bacilli, 2-4 μm × 0.6 μm in size, noncapsulate and nonsporing. The bacilli were motile. The growth was then subjected to identification by the automated Mini API system (bioMe΄rieux, Marcy l'Etoile, France). The isolate was identified as S. enterica subspecies enterica serotype paratyphi A. The isolate was further confirmed by serotyping using specific antisera following standard guidelines.  Antibiotic susceptibility tests were performed using ATB G-5 strips and read by the ATB New API reference system (bioMe΄rieux, Marcy l'Etoile, France). Antibiogram results were expressed as susceptible, intermediate, or resistant according to the criteria of the Clinical Laboratory Standards Institute M100-S19 (2009).  The isolate was found to be resistant to: Ampicillin (MIC ≥32 μg/ml), Amoxicillin-clavulanic acid (MIC ≥32/16 μg/ml), Piperacillin/Ticarcillin (MIC ≥16 μg/ml), trimethoprim/sulfamethoxazole (MIC ≥4/76 μg/ml), Cephalothin(MIC ≥16 μg/ml), Cefuroxime (MIC ≥16 μg/ml), Cefepime (MIC ≥32 μg/ml), Cefoxitin (MIC ≥16 μg/ml), Cefotaxime (MIC ≥64 μg/ml), and ceftazidime (MIC ≥32 μg/ml). However, it was susceptible to Carbapenems: Imipenem/Meropenem (MIC ≤4 μg/ml), Aminoglycosides: Gentamicin (MIC ≤4 μg/ml), Amikacin (MIC ≤16 μg/ml), Ciprofloxacin (MIC ≤1 μg/ml). Disc diffusion test using both cefotaxime (30 μg) and ceftazidime (30 μg), alone and in combination with clavulanic acid (10 μg) were performed. The zone diameter was found to increase by >5 mm for either antimicrobial agent tested in combination with clavulanic acid versus the zone diameter of the agent when tested alone, thereby confirming the presence of ESBL.  The patient was administered tablet Azithromycin 500 mg once daily. Within 24 h, the patient's temperature came down and after 48 h, the patient became afebrile.
Reports of increased incidence of drug-resistant Salmonella Paratyphi A have been reported in India and worldwide. ,,,,,, In a study from North India, Chandel et al. reported a sudden surge in Salmonella Paratyphi A organisms resistant to chloramphenicol and cotrimoxazole and with a higher MIC to ciprofloxacin.  In a recent study in South India, Harish et al. reported a sudden increase in the enteric fever cases caused by Salmonella Paratyphi A with increasingly high-level fluoroquinolone resistance.  However, ESBL-producing Salmonella Paratyphi A has been reported in comparatively few instances. ,, ESBL production in Salmonella Paratyphi A was reported for the 1 st time in 2006 by Pokharel et al. in Nepal.  Nepal has seen increasing incidence of ESBL-producing Salmonella Paratyphi A from 3 cases in 2006 to 180 cases in 2012. , One case of ESBL-producing Salmonella Paratyphi A was reported in a Japanese patient in 2013.  To the best of our knowledge, ESBL-producing Salmonella Paratyphi A has not been reported earlier from India.
The present ESBL-producing isolate was most probably community-acquired as there was no previous history of hospitalization. As ESBLs are mostly encoded on mobile genetic elements such as conjugative plasmids, transposons, and integrons, they can spread easily.  Potential increase of community acquired ESBL producing Salmonella Paratyphi A in the future would pose a serious threat to public health.  This is of particular concern for the treatment of salmonellosis in children because the use of fluoroquinolones is not recommended in the pediatric age group.  Azithromycin is a suitable drug against ESBL producing Salmonella spp.  It is capable of achieving very high intracellular concentrations, (50-100 times greater than serum levels), and this could explain its efficacy against Salmonella spp. 
To the best of our knowledge, this is the first case of ESBL producing Salmonella Paratyphi A reported from India. The emergence of ESBL producing strains of Salmonella Paratyphi A is cause for concern as Salmonella Paratyphi A infection is becoming increasingly common in the Indian subcontinent and already exhibits high levels of resistance to fluoroquinolones.  Hence, we advocate routine investigation for ESBL detection in patients presenting with enteric fever due to Salmonella Paratyphi A.
The authors acknowledge with gratitude the immense help given by Mr. Kasara during all stages of the work.
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