Improved detection of Shigella using Escherichia coli medium enrichment: Polymerase chain reaction from stool samples

Antimicrobial resistance in Shigella species: Our five years (2015-2019) experience in a tertiary care center in north India

PURPOSE

Shigella is the second leading cause of diarrhoeal mortality especially in children <5 years of age in African and Asian countries. Rapid changes are occurring in the epidemiology of shigellosis and Shigella are increasingly becoming highly drug resistant. To determine the serogroup distribution and antimicrobial resistance of Shigella isolated at our tertiary care centre in North India.

METHODS

A retrospective study was conducted where demographic details along with antimicrobial susceptibility data of Shigella isolated from stool specimens from 1st January 2015 till 31st December 2019 were retrieved from records and analyzed by WHONET 2019 software.

RESULTS

Shigella species was isolated in 1.31% (n = 137) of a total of 10,456 stool samples. Males predominated (n = 82; 59.8%) and majority of cases were admitted (n = 94; 68.6%). Children ≤5 years of age (n = 47; 34.3%) were the most commonly affected. Adults in the 21-40 age group contributed 27% of cases (n = 37). Overall, Shigella flexneri (n = 87; 63.5%) was the most common serogroup followed by non-agglutinable Shigella (n = 28; 20.4%) while Shigella sonnei (n = 12, 8.8%) and Shigella boydii (n = 9, 6.6%) fluctuated over the years. Shigella dysenteriae reappeared in 2019 after a hiatus of ten years. Overall, 45.3% (n = 62) of isolates were multidrug resistant to CLSI recommended drugs and high resistance was noted for ampicillin/amoxicillin (68.1%), cotrimoxazole (75.8%) ciprofloxacin (61.5%) and ceftriaxone/cefotaxime (45.2%).

CONCLUSIONS

Shigella have become highly drug resistant to fluoroquinolones and cephalosporins. Community based studies are required to truly assess the burden of AMR in India.

Prevalence and antimicrobial profile of Shigella isolates in a tertiary care hospital of North Karnataka: A 12-year study

Context

Shigella is a common cause of bacillary dysentery. Although it is reported worldwide, the majority of the infections are seen in developing countries with Shigella flexneri being the most common isolate. Prevalence of Shigella species and their antibiotic susceptibility profiles vary according to geographic area and season.

Aims

In the present study, the epidemiology and antimicrobial profile of Shigella from stool samples received at our hospital for a period of 12 years (January 2006 to December 2017) was evaluated.

Subjects and Methods

A total of 4578 stool samples were collected from the cases of acute gastroenteritis and diarrhoea. Samples were processed for culture and sensitivity according to standard microbiological techniques. The presumptive identification of Shigella species was done using standard conventional biochemical tests and confirmed using antisera.

Results

A total of 189 (4.2%) samples yielded Shigella spp. Isolation of Shigella spp. were more frequent from males (58.2%). S. flexneri was the commonest species isolated (47.6%) followed by Shigella sonnei(11.6%), Shigella dysenteriae (4.2%) and Shigella boydii (2.1%). Non-typeable Shigella was commonly recovered. The isolates showed high resistance to ampicillin (76.7%) and co-trimoxazole (75%) while highest susceptibility was observed to ceftriaxone (79.2%).

Conclusions

S. flexneri was the most prevalent species isolated at this centre. Shigella isolates from the study showed alarming resistance to recommended antibiotics. Non-typeable Shigella accounted for 34.4% isolates. Molecular discrimination between Shigella and Escherichia coli is essential.

Culture-positive shigellosis cases are epidemiologically different to culture-negative/PCR-positive cases

OBJECTIVE

To review the epidemiological differences between culture-positive and culture-negative (but ipaH PCR-positive) cases of shigellosis in Sydney Local Health District (SLHD), NSW, to inform whether changes to the national case definition for shigellosis are required.

METHODS

An audit of all cases of shigellosis (culture-positive vs. culture-negative/PCR-positive) in SLHD from 1 January 2013 to 30 June 2015 was conducted and demographic, clinical and risk factors were analysed and compared between these groups.

RESULTS

Of the 148 shigellosis cases notified to SLHD, 122 cases (85 culture-positive vs. 37 culture-negative) were included for analysis. Culture-positive cases were more likely than culture-negative/PCR-positive cases to have experienced at least three symptoms (OR 3.18, 95%CI 1.3-7.5), been hospitalised (OR 4.2, 95%CI 1.4-13.2), and have had men-who-have-sex-with-men exposure identified as the source of their infection (OR 28.7, 95%CI 6.2-132.6).

CONCLUSIONS

This study has identified that culture-positive vs. culture-negative/PCR-positive shigellosis cases in NSW differ by clinical severity and risk factors for infection. Implications for public health: The study findings warrant further research to determine the true diagnostic prevalence of Shigella in the culture-negative/PCR-positive group in the Australian context, in order to inform further changes to the national case definition for shigellosis.