Extensively Drug-Resistant (XDR) Enteric Fever in Children

By Sana Ashraf¹, Mehtab Hussain², Asma Noreen², Falak Abro², Nadeem Noor², Ramla Rahman³

Doi: https://doi.org/10.36283/ziun-pjmd14-1/015

How to cite: Ashraf S, Hussain M, Noreen A, Abro F, Noor N, Rahman R Extensively Drug-Resistant (XDR) Enteric Fever in Children. Pak J Med Dent. 2025 Jan ;14(1): 95-101. Doi: https://doi.org/10.36283/ziun-pjmd14-1/015.

Received: Tue, March 12, 2024 Accepted: Tue, November 19, 2024 Published: Fri, January 10, 2025.

Background: Typhoid and paratyphoid fevers are caused by Salmonella enterica subspecies serovars typhi (Salmonella typhi and Paratyphi) and the term enteric fever is generally used to describe both. This study was done to determine the frequency of extensively drug-resistant (XDR) in children diagnosed with enteric fever at a tertiary care hospital.

Methods: This cross-sectional study was conducted at the Department of Pediatric Medicine, Liaquat National Hospital, Karachi, Pakistan, from April 2023 to September 2023. A total of 122 children aged between 2-12 years with an axillary body temperature >38.4 ^oC for at least 4 days were analyzed. Non-probability convenient sampling method was adopted. Venous blood (3-5 ml) was drawn and sent for confirmation of XDR enteric fever. Effect modifiers were stratified concerning the frequency of XDR enteric fever, and post-stratification, a chi-square test was applied to take p<0.05 as significant.

Results: Out of a total of 122 children, 67 (54.9%) were boys. The mean age was 6.14±2.82 years. Blood culture was found positive for Salmonella typhi in 82 (67.2%) children. In a total of 82 patients with positive blood cultures for enteric fever, XDR was identified in 43 (52.4%) children. Relatively higher duration of fever was significantly associated with positive blood culture cases for Salmonella typhi ((>14 days, p=0.020), and XDR cases (p=0.031). Comparison of mean length of hospital stay (7.27±1.68 vs. 7.77±2.2 days, p=0.103) did not reveal any significant differences among study participants.

Conclusion: A very high prevalence of XDR was found among children diagnosed with enteric fever.

Keywords: Enteric Fever, Extensively Drug Resistant, Blood Culture, Hospital Stay, Salmonella Typhi.

Typhoid and paratyphoid fevers are caused by Salmonella enterica subspecies serovars typhi (Salmonella typhi and Paratyphi) and the term enteric fever is generally used to describe both¹. Data reveal 14.3 million cases of typhoid and paratyphoid annually, worldwide, while South Asia makes around 69.6% of all the fatalities due to typhoid and paratyphoid fever^2,3.

Due to insufficient access to safe drinking water, poor sanitation, and hygiene, enteric fever is widespread in South Asian nations with few resources, including Pakistan³. There have been reports of rates as high as 1000 cases of enteric fever per 100,000 children annually in Karachi, making it one of the most prevalent bacteremic diseases in Pakistan⁴. The Sindh province witnessed an outbreak of XDR typhoid fever from 2016-2018. The Pakistan Health Authorities reported 5,274 XDR cases out of 8,188 typhoid fever cases⁵. A survey conducted recently indicates that just 20% of Pakistan’s population has access to safe drinking water⁵.

Large survey data reveals trends reveal n “antimicrobial resistance (AMR)” while 52% of Salmonella typhi isolates tested positive for multidrug resistance (MDR)^2,6. Others have also shown that S. Typhi, has become resistant to antibiotics, leading to the emergence of MDR strains⁷. MDR microorganisms are not impacted by conventional 1^st line antibiotic medications including ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol. MDR strains can occasionally be resistant to 2^nd line medications like fluoroquinolones, particularly among Asian and African population. A strain of S. Typhi that is extensively drug-resistant (XDR) to all 1^st and 2^nd line typhoid fever medicines as well as third-generation cephalosporins has been discovered in Pakistan⁸.

The XDR strain is susceptible to a small number of medications, including azithromycin, which some individuals cannot tolerate. Therefore, overuse of broad-spectrum antibiotics like meropenem can result in the spread of untreatable strains of bacteria and serious typhoid sequelae, which can spark an epidemic⁹. There are currently no international treatment recommendations available due to the novelty of XDR S. Typhi. There are few available treatments, and there is no information on how well XDR Typhoid treatments work. The current data would be crucial for creating treatment plans for people with XDR typhoid. Additionally, a more reliable clinical trial for the treatment of XDR enteric fever may be conducted using observational data from this study¹⁰. This study aimed to determine the frequency of XDR enteric fever in children at a tertiary care hospital of Karachi, Pakistan. The findings of this study may prove helpful in framing guidelines regarding the selection of antibiotics. Moreover, our results may also assist in early recognition and treatment strategy for suspected XDR cases.

This cross-sectional study was conducted at the Department of Pediatric Medicine, Liaquat National Hospital, Karachi, Pakistan, from April 2023 to September 2023. A sample size of 122 was calculated using the WHO sample size calculator, taking the estimated proportion of MDR enteric fever as 28%¹¹, with a confidence level of 95%, and a margin of error of 8%. Sample selection was made using the non-probability convenient sampling methods. The inclusion criteria were both male and female children between 2-12 years of age with an axillary body temperature >38.4 ^oC (measured by a mercury thermometer for 2 minutes) at the time of admission for at least 4 days. The exclusion criteria were children with severe complications, including coma, sepsis syndrome or shock, or intestinal bleeding or perforation. Those who were using 3^rd generation cephalosporin, azithromycin, or meropenem at the time of admission or presented with malaria or any other apparent infectious disease were also excluded. An approval from the institutional ethical committee was obtained (letter number 0529-2020-LNH-ERC, dated June 01, 2020). Following the “Helsinki Declaration” guidelines, all the parents/guardians were briefed about the objectives, benefits, and safety of the study. Assurance of their data confidentiality was provided to them, and then informed and written consent was obtained from each parent/guardian.

Demographic information was recorded at the time of enrollment. Before initiating the therapy, 3-5 ml of venous blood was drawn into Bactec Peds Plus culture vials using aseptic measures and sent to the institutional laboratory within 1 hour following the collection for the confirmation of XDR enteric fever. Enteric fever was defined as a culture-proven case of Salmonella typhi in a child who presented with a gradual onset of fever of at least 4 days duration with anorexia, abdominal pain/abdominal distention, and vomiting. Inoculated samples were incubated for 7 days at 37 ˚C and subcultures were made on MacConkey agar plates as and when the machine indicated. Salmonella poly- and monovalent antisera and serological agglutination were used to confirm the serovar. Ampicillin (10 µg), chloramphenicol (30 µg), co-trimoxazole (25 µg), ciprofloxacin (5 µg), ceftriaxone (30 µg), meropenem (10 µg), imipenem (10 µg), and azithromycin (15 µg) were 8 antimicrobial discs used in antimicrobial susceptibility testing utilizing the Mueller Hinton agar medium for the “Kirby Bauer disc diffusion method”. Discs were incubated further for 16 hours at 37 ˚C. Zone sizes (area of no growth around the disk) were measured in millimeters using a ruler. Following the “Clinical and Laboratory Standards Institute (CLSI)” 2013 guidelines, the interpretation of zones as sensitive, intermediate, or resistant was made.¹³ Escherichia coli ATCC 25922 was used as a control. Isolates resistant to ciprofloxacin, co-trimoxazole, chloramphenicol, ampicillin, and ceftriaxone were deemed XDR positive. All the necessary and relevant information was recorded on a proforma, specially designed for this purpose.

The data was entered and analyzed using the “IBM-SPSS Statistics” version 26.0. Representation of the quantitative variable (like age, height, weight, monthly income, and length of stay in the hospital) was done by calculating mean and standard deviation (SD). Qualitative or categorical variables like sex, XDR (yes/no), and socioeconomic status were described through frequency and percentage. Stratification was done with regard to age and gender. The effect of socioeconomic status, length of hospital stay, residence, height, weight, and age (effect modifiers) on outcome (XDR positive) was calculated by applying the chi-square test, considering p<0.05 as significant.

Out of a total of 122 children, 67 (54.9%) were boys. The mean age, weight and height were 6.14±2.82 years, 20.30± 6.08 kg and 110.17±15.91 cm, respectively. Socio-economic status of 53 (43.5%) children was low. There were 41 (33.6%) children who were reported to have good personal hygiene. The mean duration of fever was 11.95±5.19 days (ranging between 4 to 30 days). Coated tongue and abdominal pain were the most common presenting clinical presentations/complaints, noted in 59 (48.4%), and 38 (31.1%) children, respectively. Table-1 is shows details about the characteristics of the studied children.

Table 1: Frequency Distribution of demographics and clinical characteristics (N=122)

Blood culture was found positive for Salmonella typhi in 82 (67.2%) children. Relatively higher duration of fever (>14 days, p=0.020) was significantly associated with positive blood culture Salmonella typhi cases. No significant association of positive blood culture with age distribution (p=0.263), gender (p=0.689), parental socio-economic status (p=0.685), or parental educational level (p=0.252) were found Table 2.

Table 2: Association of Positive Blood Culture with the Characteristics of Patients (N=122)

In a total of 82 patients with positive blood cultures for enteric fever, XDR was identified in 43 (52.4%) children. Relatively higher duration of fever (>14 days, p=0.031) was significantly associated with XDR cases. No significant association of XDR with age distribution (p=0.109), gender (p=0.598), parental socioeconomic status (p=0.269), or parental educational level (p=0.352) was found (Table 3). Comparison of mean length of hospital stay (7.27±1.68 vs. 7.77±2.2 days, p=0.103) did not reveal any significant differences among study participants.

Table 3: Stratification of Study Variables Concerning XDR Among Culture-Positive Cases (N=82)

The continuous increase in the trend of S. Typhi XDR cases among the Pakistani population is quite disturbing and shocking⁵. Effective management has become challenging due to the recent increase in XDR S. Typhi strains being resistant to both 1^st line and 2^nd line treatments^12,13. Specifically, in children due to a poor immune system, the complications of enteric fever are severe. Unfortunately, lack of delivery of basic health care facilities like provision of clean water, proper sanitation, and awareness about frequent hand washing are important contributor to spreading the burden of disease. Although azithromycin, carbapenems, tigecycline, piperacillin-tazobactam, ceftazidime-avibactam, fosfomycin, and colistin are among the best treatments for XDR S. Typhi, additional studies are needed to determine their effectiveness. In the current study, 67% of blood cultures tested positive for Salmonella typhi. A study conducted by Ali el al demonstrated that the frequency of positive blood cultures with Salmonella typhi was about 78.7%¹⁴. Although, the frequency of positive blood cultures seems high in Pakistan, the marginal increase in the findings of Ali et al could be due to the larger age group of subjects that were analyzed. Data from neighboring India in a study conducted by Srinivasan et al revealed a much lesser proportion of Salmonella enterica serovar Typhi/Paratyphi culture positivity cases (3.8%). A much lesser proportion of positive blood culture cases in Srinivasan et al findings could be due to highly stringent criteria for the suspected enteric fever among subjects analyzed and considered for blood culture evaluation¹⁵.

Among positive blood culture reports, 52.4% had XDR S. Typhi. Yousafzai et al from Karachi showed that about 63.5% of subjects had confirmed XDR S. Typhi⁴. Our findings coupled with Yousafzai et al exhibit that a huge percentage of our population is affected by XDR enteric fever. Between 2009 and 2011, the laboratory monitoring data in Karachi, Pakistan, showed a notable rise in the prevalence of multidrug-resistant S. Typhi. During this period, there was a very low incidence of occasional third-generation cephalosporin resistance, estimated at just 0.08%¹⁶. More recently, Jabeen et al described that XDR isolates circulating in Pakistan had effectively acquired genes responsible for resistance to both 1^st and 2^nd line antibiotics. Additionally, these isolates had acquired CTX-M genes, which are extended-spectrum beta-lactamases (ESBLs), making them resistant to 3^rd generation cephalosporins. This indicates a concerning level of antibiotic resistance in these pathogens¹³. The surge in XDR is not only a cause for alarm within the country but also a significant concern for global healthcare. There is a growing apprehension about the potential for international outbreaks as a result of this rise in drug-resistant pathogens.

Immunization emerges as a successful and cost-effective short-term strategy to reduce the prevalence of S. Typhi^17,18. However, for sustainable, long-term solutions, it is imperative to address fundamental factors^19,20. This involves ensuring access to clean drinking water, implementing sanitation systems to minimize fecal environmental contamination, and promoting practices that avoid the consumption of contaminated food²¹. These comprehensive measures contribute not only to immediate disease control through immunization but also to the establishment of enduring solutions for the prevention and reduction of S. Typhi in the broader context of public health^22,23. The general population’s access to clean drinking water in each of the signatory nations is one of the “United Nations Sustainable Development Goals” and is crucial to their quality of life and overall welfare^24,25. Creating awareness at the basic level in the form of parental counseling may help us mitigate the magnitude of the problem and improve the outcome of the pediatric population.

A single study center and a modest sample size were some of the limitations of this research. We were unable to record treatment outcomes in the present set of patients.

Very high prevalence of XDR was found among children diagnosed with enteric fever. The emergence of XDR strains poses a growing health concern that warrants attention and proactive measures.

The authors are thankful to all the children and their parents who were involved in this study.

The authors have no conflict of interest.

None

Approval from the institutional ethical committee was obtained through letter number 0529-2020-LNH-ERC, dated June 01, 2020.

SA contributed in data collection, drafting, and is responsible for data’s integrity. MH contributed in design, conception of the idea, proof read, and critical revisions. AN conceived the idea, data analysis, and did critical review. FA did manuscript editing, data analysis and data interpretation. NN did manuscript editing, proof reading and critical revisions. RR did manuscript editing, literature review, proof reading and critical revisions.

1. Amsalu T, Genet C, Adem Siraj Y. Salmonella Typhi and Salmonella Paratyphi prevalence, antimicrobial susceptibility profile and factors associated with enteric fever infection in Bahir Dar, Ethiopia. Sci Rep. 2021;11(1):7359. doi:10.1038/s41598-021-86743-9
2. Yousafzai MT, Irfan S, Thobani RS, Kazi AM, Hotwani A, Memon AM, et al. Burden of culture confirmed enteric fever cases in Karachi, Pakistan: Surveillance for Enteric Fever in Asia Project (SEAP), 2016-2019. Clin Infect Dis. 2020;71(Supplement_3):S214-S221. doi:10.1093/cid/ciaa1308
3. Crump JA, Mintz ED. Global trends in typhoid and paratyphoid fever. Clin Infect Dis. 2010;50(2):241-246. doi:10.1086/649541
4. Yousafzai MT, Qamar FN, Shakoor S, Saleem K, Lohana H, Karim S, et al. Ceftriaxone-resistant Salmonella Typhi outbreak in Hyderabad City of Sindh, Pakistan: high time for the introduction of typhoid conjugate vaccine. Clin Infect Dis. 2019;68(Supplement_1):S16-S21. doi:10.1093/cid/ciy877
5. Rasheed MK, Hasan SS, Babar Z, Ahmed SI. Extensively drug-resistant typhoid fever in Pakistan. Lancet Infect Dis. 2019;19(3):242-243. doi:10.1016/S1473-3099(19)30051-9
6. Carey ME, MacWright WR, Im J, Meiring JE, Gibani MM, Park SE, et al. The surveillance for enteric fever in asia project (SEAP), severe typhoid fever surveillance in Africa (SETA), surveillance of enteric fever in India (SEFI), and strategic typhoid alliance across Africa and Asia (STRATAA) population-based enteric fever studies: A Review of methodological similarities and differences. Clin Infect Dis. 2020;71(Supplement_2):S102-S110. doi:10.1093/cid/ciaa367
7. Khan M, Shamim S. Understanding the Mechanism of Antimicrobial Resistance and Pathogenesis of Salmonella enterica Serovar Typhi. 2022 Oct 11;10(10):2006. doi: 10.3390/microorganisms10102006
8. Jabeen K, Saleem S, Jahan S, Nizamudin S, Arshad F, Huma ZE, et al. Molecular Characterization of Extensively Drug Resistant Salmonella Enterica Serovar Typhi Clinical Isolates from Lahore, Pakistan. Infect Drug Resist. 2023 May 12;16:2987-3001. doi: 10.2147/IDR.S406253
9. Butt MH, Saleem A, Javed SO, Ullah I, Rehman MU, Islam N, et al. Rising XDR-Typhoid Fever Cases in Pakistan: Are We Heading Back to the Pre-antibiotic Era? Front Public Health. 2022 Jan 17;9:794868. doi: 10.3389/fpubh.2021.794868
10. Qureshi S, Naveed AB, Yousafzai MT, Ahmad K, Ansari S, Lohana H, et al. Response of extensively drug resistant Salmonella Typhi to treatment with meropenem and azithromycin, in Pakistan. PLOS Negl Trop Dis. 2020;14(10):e0008682. doi:10.1371/journal.pntd.0008682
11. Iqbal M, Mirza S, Hassan MA, Srichand K, Bugti S. Prevalence and current trends of antimicrobial resistance among Salmonella typhi and Salmonella paratyphi A in children. Isra Med J. 2019;11(1):41-45.
12. Butt MH, Saleem A, Javed SO, Ullah I, Rehman MU, Islam N, et al. Rising XDR-Typhoid Fever Cases in Pakistan: Are We Heading Back to the Pre-antibiotic Era?. Front Public Health. 2022;9:794868. doi:10.3389/fpubh.2021.794868
13. Jabeen K, Saleem S, Jahan S, Nizamudin S, Arshad F, Huma Z, et al. Molecular Characterization of Extensively Drug Resistant Salmonella Enterica Serovar Typhi Clinical Isolates from Lahore, Pakistan. Infect Drug Resist. 2023;16:2987-3001. doi:10.2147/IDR.S406253
14. Ali A, Ali HA, Shah FH, Zahid A, Aslam H, Javed B. Pattern of antimicrobial drug resistance of Salmonella Typhi and Paratyphi A in a Teaching Hospital in Islamabad. J Pak Med Assoc. 2017;67(3):375-379.
15. Srinivasan M, Sindhu KN, Ramanujam K, et al. Factors Predicting Blood Culture Positivity in Children With Enteric Fever. J Infect Dis. 2021;224(Supple 5):S484-S493. doi:10.1093/infdis/jiab357
16. Qamar FN, Azmatullah A, Kazi AM, Khan E, Zaidi AKM. A three-year review of antimicrobial resistance of Salmonella enterica serovars Typhi and Paratyphi A in Pakistan. J Infect Dev Ctries. 2014;8(8):981–986. doi: 10.3855/jidc.3817
17. Vanderslott S, Kumar S, Adu-Sarkodie Y, Qadri F, Zellweger RM. Typhoid Control in an Era of Antimicrobial Resistance: Challenges and Opportunities. Open Forum Infect Dis. 2023;10(Suppl 1):S47-S52. doi:10.1093/ofid/ofad135
18. Nampota-Nkomba N, Carey ME, Jamka LP, Fecteau N, Neuzil KM. Using Typhoid Conjugate Vaccines to Prevent Disease, Promote Health Equity, and Counter Drug-Resistant Typhoid Fever. Open Forum Infect Dis. 2023 Jun 2;10(Suppl 1):S6-S12. doi: 10.1093/ofid/ofad022
19. Ehuwa O, Jaiswal AK, Jaiswal S. Salmonella, Food Safety and Food Handling Practices. 2021 Apr 21;10(5):907. doi: 10.3390/foods10050907
20. Mkangara M. Prevention and Control of Human Salmonella enterica Infections: An Implication in Food Safety. Int J Food Sci. 2023 Sep 11;2023:8899596. doi: 10.1155/2023/8899596
21. Tharwani ZH, Kumar P, Salman Y, Islam Z, Ahmad S, Essar MY. Typhoid in Pakistan: Challenges, Efforts, and Recommendations. Infect Drug Resist. 2022;15:2523-2527. doi:10.2147/IDR.S365220
22. Montero DA, Vidal RM, Velasco J, Carreño LJ, Torres JP, Benachi O MA, et al. Two centuries of vaccination: historical and conceptual approach and future perspectives. Front Public Health. 2024 Jan 9;11:1326154. doi: 10.3389/fpubh.2023.1326154
23. Appiah GD, Chung A, Bentsi-Enchill AD, Kim S, Crump JA, Mogasale V, et al. Typhoid Outbreaks, 1989-2018: Implications for Prevention and Control. Am J Trop Med Hyg. 2020 Jun;102(6):1296-1305. doi: 10.4269/ajtmh.19-0624
24. Renganathan E, Davies P. Sustainable Development Goals and the role of and implications for primary care physicians. Malays Fam Physician. 2023;18:54. doi:10.51866/cm0005
25. Yousafzai MT, Irfan S, Thobani RS, Kazi AM, Hotwani A, Memon AM, et al. Burden of Culture Confirmed Enteric Fever Cases in Karachi, Pakistan: Surveillance For Enteric Fever in Asia Project (SEAP), 2016-2019. Clin Infect Dis. 2020 Dec 1;71(Suppl 3):S214-S221. doi: 10.1093/cid/ciaa1308.

This is an open-access article distributed under the terms of the CreativeCommons Attribution License (CC BY) 4.0 https://creativecommons.org/licenses/by/4.0/