ABSTRACT
Objectives: In May 2018, a laboratory network for antimicrobial resistance (AMR) surveillance in Tamil Nadu, India, detected a cluster of Salmonella enterica serotype Typhi (S. Typhi) isolates resistant to ceftriaxone. We investigated to describe the epidemiology and identify risk factors for the outbreak. Methods: We conducted unmatched case-control studies. We defined a case as illness (fever with abdominal pain, diarrhea or vomiting) in a person with blood culture-confirmed ceftriaxone-resistant S. Typhi isolated between January 1 and July 4, 2018 in Tiruchirappalli, Tamil Nadu. We interviewed cases using a semi-structured questionnaire to identify common exposures to food, water and places visited. Results: We identified 7 cases (5 men) during March 25-June 8, 2018, median age 23 years (range: 12-42); all were hospitalized, none died. Eating at Restaurant A (odds ratio [OR]=22) and chicken gravy (OR=16) was associated with illness. Of the 10 workers at Restaurant A, stool culture from 8 did not detect S. Typhi; 2 did not consent to provide samples. Five water samples around the restaurant showed low or no residual chlorine content. Conclusions: The investigation highlights the value of AMR surveillance in detecting emerging pathogens and the need for timely investigations, along with strengthening food safety.
ABSTRACT
BACKGROUND: Conus amadis is a carnivorous snail found abundantly in coastal waters of India. Despite its abundance in southern coastal waters of India and the fact that most of the conotoxin act in neuronal system, research work on Conus amadis venom was not much focused. So we have made a brief study on the venom complex of Conus amadis to identify the library of novel conotoxins and to screen the natural venom for neurological function. OBJECTIVE: De novo sequencing of novel conopeptides from the venom cocktail of Conus amadis and to screen its natural venom for the presence of biological activities in zebrafish model. METHODS: Proteome based MALDI-TOF and LC-MS-MS analysis for identification of novel conotoxins and subsequent sequencing. Due to the complex disulfide rich nature of the venom peptides, the study also involves global chemical modification experiments of the venom extract to unambiguously determine the sequence of novel conotoxins. Biological function analysis of natural venom was tested in zebrafish model to ascertain anti-epileptic properties. RESULTS: In this study, we have identified 19 novel conotoxins containing 1, 2 & 3 disulfides, belonging to different classes. Among them, 2 novel contryphans, 3 T-superfamily conotoxins, 2 A-superfamily conotoxins and 2 Mini M-Superfamily conotoxins were sequenced to its amino acid level from the fragmented spectrum of singly and doubly charged parent ions using de novo sequencing strategies. ama1054, a contryphan peptide toxin, possesses post translationally modified bromo tryptophan at its seventh position. Except ama1251, all the sequenced peptide toxins possess modified C-terminal amidation. Crude venom exhibited anticonvulsant properties in pentylenetetrazole-induced seizure in zebrafish larvae, which suggested anti-epileptic property of the venom cocktail. Acetylcholinesterase activity was also identified in the venom complex. CONCLUSION: Based on the preliminary evidence, if this study is extended further through bioassay guided purification, could possibly yield peptide toxins with anticonvulsant and other neurologically active molecules.
