Subarna Roy

Distribution of Shigella enterotoxin genes and secreted autotransporter toxin gene among diverse species and serotypes of shigella isolated from Andaman Islands, India

We studied the prevalence and distribution of the newly described genes for Shigella enterotoxins (ShET1 and ShET2, encoded by set and sen genes) and secreted auto‐transporter toxin (encoded by sat gene) in clinical isolates from the Andaman Islands, India. A total of 153 Shigella isolates obtained from hospitalized patients during 1994–2004 were analysed. These isolates included all the four species of Shigella (S. dyseteriae– 29, S. flexneri– 75, S. sonnei– 38, S. boydii– 5) that belonged to diverse serotypes (including serologically untypable – 6) and each serotype included a wide variety of genotypes. Each isolate underwent polymerase chain reaction (PCR) for detection of set, sen and sat genes employing specific primers. We found the set gene in all S. flexneri 2a and 2b isolates (41 of 41, 100%) but not outside S. flexneri serotype 2. The sen gene was well distributed among all species and serotypes but its presence was apparently low at 49.1% (75 of 153), probably because of the loss of the large plasmid that harbours the gene in 76 of the 78 (97.4%) sen negative isolates. Also, all S. flexneri 2 isolates (including 2a and 2b serotypes) had the sat gene. It was present in 96% (72 of 75) of S. flexneri, in 6.9% (2 of 29) of S. dysenteriae, in 20% (1 of 5) of S. boydii, and in 33.3% (2 of 6) of untypable Shigella, but not in (0 of 38) S. sonnei. This study provides initial data on the prevalence and distribution of of the set, sen and sat genes in a wide variety of Shigella isolated over a 10‐year period. Our results suggest a greater prevalence of the set and sat genes in S. flexneri 2 isolates than previously thought and might help in future pathochip designs.

Chikungunya Fever, Andaman and Nicobar Islands, India

To the Editor: The outbreak of chikungunya fever that started in the Indian Ocean Islands in early 2005 (1) spread through adjoining islands and appeared in peninsular India by late 2005 (2). It was first noticed in the southern state of Andhra Pradesh in February 2006; it spread to Tamil Nadu in April 2006 and to Karnataka and Kerala in May. The western state of Gujarat also reported cases in April, but no cases were reported in May and June. The disease again reappeared in July and reached a peak in August. Later it affected the central Indian states of Maharashtra and Madhya Pradesh. In most states, the outbreak declined by October 2006 (3,4). Andaman and Nicobar Islands, a union territory of India, is an archipelago of >500 islands and islets situated in the Bay of Bengal, 1,200 km from peninsular India. People are constantly moving between mainland India and these islands. Chikungunya fever has previously not been reported from these islands. During July and August 2006, medical professionals noticed an increase in the number of cases of febrile illness in Port Blair, the headquarters of the union territory and the only urban area in the islands. The total number of patients with fever who visited the 5 urban health centers (UHC) in the town went up from the baseline of 300–450 per day to 550–900 per day in July and August 2006. Most of the patients had associated joint pain. In view of the clinical features suggestive of chikungunya fever, the ongoing epidemic on mainland India, and the widespread presence of the vector, Aedes aegypti, within the urban area of Port Blair (5), chikungunya fever was suspected. To confirm this hypothesis, 17 persons who fulfilled the case definition of having an acute febrile illness associated with severe pain in multiple joints were selected from among the initial patients who went to the UHCs and the referral hospital in Port Blair. Among these study participants, 15 were adults and 2 were adolescents 15 years of age; 6 were female and 11 male. Four adults had febrile illness associated with joint pain; in these patients, weakness of all 4 limbs developed 3–15 days after onset of illness. All of the 4 patients with weakness had areflexic quadriplegia; 1 required ventilatory support. The patients with areflexic quadriplegia were treated with injections of methylprednisolone; all recovered within a week. Blood samples were collected from these study participants. Serum samples were separated and sent to the National Institute of Virology, Pune, for detection of anti–chikungunya virus (CHIKV) immunoglobulin M (IgM) antibodies. Samples were collected from 12 patients >4 days after the onset of symptoms. In the remaining patients, the interval between onset of symptoms and collection of blood samples was <4 days. Of the 17 study participants, 13 were positive for anti-CHIKV IgM antibodies. Three of 4 samples that were negative for IgM antibodies to CHIKV were collected <3 days after the onset of symptoms. Among these, 2 samples were subjected to reverse transcriptase–PCR by using the primers CHIKV/E1S (5′-TAC CCA TTC ATG TGG GGC-3′) and CHIKV/E1C (5′-GCC TTT GTA CAC CAC GAT T-3′), as described by Hasebe et al. (6); both were positive for CHIKV RNA. All these samples were tested for dengue IgM antibodies by using SD Bioline Dengue IgM Rapid Test (Standard Diagnostics Inc., Kyonggi-Do, South Korea), which uses a mixture of dengue recombinant envelop proteins and can detect all of the 4 dengue serotypes. None of the samples tested positive for dengue antibodies. Hence, CHIKV infection was confirmed in 15 of 17 patients. India experienced the first confirmed outbreak of chikungunya fever in 1963–1964 in Kolkata (7) and in 1965 in Chennai. The last epidemic in India was reported from Barsi in the state of Maharastra in 1973 (8). However, during these outbreaks, Andaman and Nicobar Islands were not affected. Outbreaks of dengue fever and chikungunya fever are known to occur simultaneously, as has happened in several parts of India. However, during the current outbreak in Andaman Islands, dengue infection was not detected. (Dengue has never been reported in the islands.) As chikungunya fever is known for its mysterious pattern of dramatic outbreaks interspersed by periods of prolonged absence, the introduction of this virus to an unexposed population has great public health importance. This outbreak could be a warning about preparedness for health authorities not only in these islands but also in other areas where chikungunya fever has not occurred previously. With the extent of human travel to and from areas with active chikungunya virus transmission, many areas where the disease has not previously been reported could be at risk. As an outbreak response, the Regional Medical Research Centre and Directorate of Health Services, Andaman and Nicobar Administration, has undertaken a comprehensive community-based survey to assess the impact of chikungunya fever and Aedes infestation levels. We are stepping up our applied field research to prevent future outbreaks of chikungunya fever, as well as dengue fever.

Rapid emergence of third-generation cephalosporin resistance in Shigella sp. isolated in Andaman and Nicobar Islands, India.

Shigellosis is a major cause of diarrheal diseases among children in Andaman & Nicobar Islands, India, which have a population of 350,000 people, including settlers from mainland India and 6 indigenous tribes. From the last one-and-half decade, we have been monitoring the species distribution and emergence of antibiotic resistance among the isolates of Shigella. The circulating Shigella strains have been found rapidly acquiring resistance to a wide spectrum of antibiotics. The recent data indicate that a significant proportion of Shigella isolates have been resistant to newer generation of cephalosporins, which are used as an alternative of quinolones to treat the patients with shigellosis. In this communication, we report the antibiotic-resistant pattern of Shigella isolates that are recently isolated from these islands. From January 2008 to December 2009, 311 stool samples were processed and 44 (14%) Shigella isolates were recovered. Out of these 44 Shigella isolates, 6 (14%) were found to be resistant to all the three third-generation cephalosporins tested. The minimum inhibitory concentrations of the resistant isolates were all above the breakpoint for reduced susceptibility as per the Clinical and Laboratory Standards Institute guidelines. All of the cephalosporin-resistant Shigella strains were confirmed to produce extended-spectrum β-lactamases. By analyzing trends in the resistance patterns of the various Shigella species, we found that Shigella dysenteriae (40%) is currently more resistant, followed by Shigella flexneri (14%), than the other Shigella species in these islands of India, especially to the third-generation cephalosporins. The acquisition of resistance by enteric pathogens to the increasing number of antibacterial drugs is becoming a grave concern, particularly in developing countries where shigellosis is of a common occurrence.

Prevalence of the plasmid-mediated quinolone resistance determinants among clinical isolates of Shigella sp. in Andaman & Nicobar Islands, India.

Aims:  This study was carried out to find the prevalence of various plasmid‐mediated quinolone‐resistant (PMQR) determinants among the quinolone‐resistant clinical isolates of Shigella sp. from paediatric patients in Andaman & Nicobar Islands.

Molecular tracking of the lineage of strains of Vibrio cholerae O1 biotype El Tor associated with a cholera outbreak in Andaman and Nicobar Islands, India

A large outbreak of acute watery diarrhoea involving all age groups of mongoloid tribal aborigines occurred during October–November, 2002 in the Nancowry group of Andaman and Nicobar Islands in the Indian Ocean. Twenty‐one of the 67 stool samples from 67 patients were positive for toxigenic Vibrio cholerae O1, serotype Ogawa biotype El Tor, which showed striking similarity in its antibiogram with some of the strains of V. cholerae O1 Serotype Ogawa biotype El Tor isolated in Kolkata. The Nancowry and Kolkata isolates were compared with molecular tools involving random amplified polymorphic DNA (RAPD) fingerprinting, ribotyping and pulsed‐field gel electrophoresis (PFGE). RAPD fingerprinting and ribotyping techniques revealed that all the V. cholerae strains associated with the outbreak in these islands were clonal in nature and identical to a population of isolates obtained from Kolkata since 1993. PFGE could discriminate within these Kolkata isolates further and established that a particular subtype of this population reached the remote Nancowry islands and was responsible for the outbreak.

A unique strain of Leptospira isolated from a patient with pulmonary haemorrhages in the Andaman Islands: a proposal of serovar portblairi of serogroup Sehgali.

Leptospirosis is endemic in the Andaman Islands, often occurring as outbreaks during the post-monsoon period. Pulmonary involvement is common and associated with high morbidity and mortality. During the investigation of an outbreak in North Andaman in 1996 an isolate was recovered from the blood of a patient with fever, headache, body aches and haemoptysis with respiratory distress as presenting symptoms. The isolate was characterized using the cross-agglutination absorption test (CAAT) and monoclonal antibodies (mAbs). The isolate showed typical morphology and characteristic motility of the genus Leptospira. Growth was inhibited at 13 degrees C and in the presence of 8-azaguanine. The isolate could not be identified with grouping sera representing 25 serogroups, CAAT and mAbs. A new serovar of a new serogroup is proposed. Genetic characterization using polymerase chain reaction (PCR) followed by sequencing of the PCR product and randomly amplified polymorphic DNA fingerprinting (RAPD) showed that the isolate was genetically similar to L. interrogans sensu stricto.

Changing patterns and widening of antibiotic resistance in Shigella spp. over a decade (2000-2011), Andaman Islands, India.

This study is a part of the surveillance study on childhood diarrhoea in the Andaman and Nicobar Islands; here we report the drug resistance pattern of recent isolates of Shigella spp. (2006-2011) obtained as part of that study and compare it with that of Shigella isolates obtained earlier during 2000-2005. During 2006-2011, stool samples from paediatric diarrhoea patients were collected and processed for isolation and identification of Shigella spp. Susceptibility to 22 antimicrobial drugs was tested and minimum inhibitory concentrations were determined for third-generation cephalosporins, quinolones, amoxicillin-clavulanic acid combinations and gentamicin. A wide spectrum of antibiotic resistance was observed in the Shigella strains obtained during 2006-2011. The proportions of resistant strains showed an increase from 2000-2005 to 2006-2011 in 20/22 antibiotics tested. The number of drug resistance patterns increased from 13 in 2000-2005 to 43 in 2006-2011. Resistance to newer generation fluoroquinolones, third-generation cephalosporins and augmentin, which was not observed during 2000-2005, appeared during 2006-2011. The frequency of resistance in Shigella isolates has increased substantially between 2000-2006 and 2006-2011, with a wide spectrum of resistance. At present, the option for antimicrobial therapy in shigellosis in Andaman is limited to a small number of drugs.

A clone of Leptospira interroganssensu stricto is the major cause of leptospirosis in the archipelago of Andaman and Nicobar Islands, India

Aims:  Andaman and Nicobar Islands in India has a century long history of human leptospirosis. Several isolates have been recovered over the years from different locations. The present study was undertaken to understand the clonal relationship between all these pathogenic leptospires recovered from these islands.

Isolation of NDM-1-producing multidrug-resistant Pseudomonas putida from a paediatric case of acute gastroenteritis, India

Pseudomonas putida is an uncommon opportunistic pathogen, usually susceptible to antimicrobial agents. Data concerning resistance to antimicrobial agents in clinical P. putida isolates are limited. To the best of our knowledge we report for the first time the isolation of NDM-1-producing multidrug-resistant P. putida from a case of acute gastroenteritis. The isolate showed resistance to a wide range of antimicrobials, including fluoroquinolones, third-generation cephalosporins and carbapenems. The isolate also exhibited multiple mutations in the quinolone resistance determining region and showed the presence of qepA, blaTEM, blaOXA1 and blaOXA7 genes. The present study highlights the importance of looking for the relatively rare aetiological agents in clinical samples that do not yield common pathogens.

In vitro antimicrobial activity of Achyranthes coynei Sant.

Objective To validate the traditional use of Achyranthes coynei (A. coynei) Sant. as an antimicrobial in treatment of various infectious diseases.