Risk Factors of Extensively Drug Resistant Typhoid Fever Among Children in Karachi: Case-Control Study

Abstract

Background Extensively drug resistant typhoid fever (XDR-TF) has been responsible for an ongoing outbreak in Pakistan, which began in November 2016. Objective This study aimed to determine the risk factors associated with XDR-TF. Methods This age- and sex-matched case-control study was conducted during May-October 2018 in Karachi. All patients with XDR-TF were identified from the laboratory-based surveillance system data. Cases included patients aged <15 years living in Karachi with culture-positive Salmonella enterica serovar Typhi with resistance to chloramphenicol, ampicillin, trimethoprim/sulfamethoxazole, fluoroquinolones, and third-generation cephalosporins. Age- and sex-matched controls included children free from the symptoms of TF, aged under 15 years, and residing in Karachi. All controls were recruited from among those who attended outpatient clinics. Results A total of 75 cases and 75 controls were included in this study. On univariate analysis, the odds of having XDR-TF were 13-fold higher among participants who used piped municipal water than among those who did not (odds ratio [OR] 12.6, 95% CI 4.1-38.6). The use of bore water was significantly associated with XDR-TF (OR 5.1, 95% CI 1.4-19.0). Cases were more likely to report eating French fries with sauce (OR 13.5, 95% CI 3.9-47.0) and poppadum (OR 3.4, 95% CI 1.7-6.7) from street vendors than controls. Boiling water at home was negatively associated with XDR-TF (OR 0.3, 95% CI 0.2-0.7). On multivariate analysis, 2 factors were independently associated with XDR-TF. Using piped municipal water (OR 10.3, 95% CI 3.4-30.4) and eating French fries with sauce from street vendors (OR 8.8, 95% CI 2.1-36.2) were significantly associated with an increased odds of XDR-TF. Conclusions Community water supply and street food eating habits were implicated in the spread of the superbug S typhi outbreak, which continues to grow in Karachi. Therefore, it is recommended to improve the community water supply to meet recommended standards and to develop a policy to improve the safety of street food. In addition, health authorities are required to conduct mass vaccination for TF among high-risk groups.

Burden of antibiotic resistance among children with typhoid in Gadap Town, Karachi, Pakistan

“…This observation is in agreement with that of a retrospective surveillance study of enteric fever cases conducted across all regions of Pakistan [22]. A recently published study from Karachi also showed that adults are less susceptible to typhoid than are children aged 5-15 years [31]. We did not detect any case of typhoid or paratyphoid in children under 2 years of age in this location.…”

“…Herein, more boys than girls were infected with S. Typhi but the sample size was insufficient to enable a statistically relevant analysis. However, the trend for greater susceptibility of male children to typhoid is consistent with other studies in which gender was considered as a risk factor for contracting enteric fever [31][32][33]. This may be associated with gender differences relating to level of exposure, wherein boys spend more time playing and eating outdoors.…”

Comparison of Single vs Combination Drug Therapy in Extensively Drug Resistant Salmonella typhi: An Observational Study from Pakistan

“…Vigho et al found community water supply and street food are the main risk factors for XDR typhoid. 19 Focus on the supply of safe potable drinking water and strict policy of street food safety should be implemented by the authorities. Vaccination against salmonella is also imperative.…”

A Study on the Clinical Profile, Blood Profile and Culture Sensitivity Pattern of Salmonella Typhi in Paediatric Patients

“…Vigiho et al in 2021 determined the risk factors associated with extensively drug-resistant typhoid fever in Pakistani children. 16 They revealed that patients using community water supply and eating from street vendors had more chances of having the drugresistant disease. Our study design and parameters differed from that of Vigiho et al but the use of boiled water was not significantly associated with the presence or absence of multi-drug resistant typhoid in our study participants.…”