ABSTRACT
Bacillus cereus is an emerging food-borne pathogen responsible for two types of food poisoning: emetic and diarrhoeal type. Here we report an emetic type of food-borne illness attributable to Bacillus cereus. On 2nd February, 2021, 202 people suffered from pain in abdomen and vomiting after consuming the rice provided during a public gathering in Diphu, Assam. Culture of leftover fried rice showed growth of Bacillus cereus group of organisms. Molecular detection of enterotoxin and emetic toxin genes was done in the isolated strains by polymerase chain reaction. Multi locus sequence typing (MLST) and phylogenetic analysis was done to characterise the isolated strains. A total of five strains of Bacillus cereus were isolated. Ces gene was found in isolates GMC22 & GMC24 and other enterotoxins producing genes were found in isolates GMC23 and GMC24. MLST identified four sequence types (STs) (ST1051, ST1616, ST998 and ST1000). Phylogenetic analysis clustered ST-1051 assigned to the GMC22 strain into the previously defined clade I and was in close relation with ST-144, representing a new cereulide-producing emetic cluster. As Bacillus cereus is a common contaminant of foods, it is essential to evaluate the pathogenic potential of the bacteria for a definite link between causative agents and the illness. MLST can be used to characterize the Bacillus cereus strains isolated from outbreak samples in order to link the probable pathogens with the illness. In this outbreak, we suggest that ST-1051 is the strain responsible for the food-borne illness, which was predominantly of emetic type.
ABSTRACT
PURPOSE: Streptococcus pneumoniae is an important human respiratory tract pathogen causing pneumococcal diseases in majority of children and adults. The capsule is a significant virulence factor of Pneumococci which determines the bacterial serotype and is the component used for synthesis of pneumococcal vaccines. This cross-sectional study aimed to isolate Streptococcus pneumoniae from clinical samples and determine the occurrence of its circulating serotypes in Assam, North East India. MATERIALS AND METHODS: A total of 80 clinical samples were collected from June 2019 to May 2020 from patients clinically suspected from pneumococcal infection and also included samples routinely sent to bacteriology laboratory. Isolation and identification of S. pneumoniae was performed using conventional culture and molecular methods. Antibiotic susceptibility patterns were monitored. Capsular serotyping was performed using PCR of cpsA gene followed by DNA sequencing. RESULTS: Majority of the cases suspected of pneumococcal infection belong to the paediatric group aged less than 5 years. Out of 80 samples, 10 (12.50%) were found to be positive by PCR of recP gene. Culture was positive in 80% (8/10) of the total positives. Co-trimoxazole resistance was seen in 33.33% of the isolate from sputum. Serotypes 6A, 6B, 6C and 19F were detected in our region, out of which 6C is a non-vaccine serotype. CONCLUSION: Continued surveillance is needed to monitor trends in non-vaccine serotypes that may emerge as highly associated with antibiotic resistance. Also, the need to continuous monitoring of the antibiotic susceptibility of S. pneumoniae in North eastern parts of India is of outmost importance.