Outbreak investigation of ceftriaxone-resistant Salmonella enterica serotype Typhi and its risk factors among the general population in Hyderabad, Pakistan: a matched case-control study

Antibiotic Utilization and Resistance According to the WHO AWaRe Classification in Intensive Care Units After COVID-19 Third Wave in Pakistan: Findings and Implications

Background and Objective: Irrational use and overuse of antibiotics is considered a major cause of antimicrobial resistance (AMR) among patients admitted to hospitals, especially in intensive care units (ICUs). ICUs are the most critical wards in healthcare settings, where the use of antibiotics is much higher compared to other wards. Therefore, the appropriate administration and monitoring of antibiotic usage in these units is a matter of concern. Materials and Methods: This retrospective study evaluated the types, utilization patterns, sensitivity, and resistance of various antibiotics used among patients admitted to the ICUs of different hospitals after the third wave of the coronavirus disease in 2019 (COVID-19) in Pakistan. Results: It was observed that more than 40% of the patients were given two antibiotics and 54.3% were given at least one antibiotic each day. A total of 768 antibiotics from different groups, based on the World Health Organization (WHO) Access, Watch, and Reserve (AWaRe) classification, were prescribed to 313 patients admitted to ICUs between April and August 2021. Among the types of antibiotics, amoxicillin/clavulanic acid was the most frequently used antibiotic (75 prescriptions). It was also observed that the majority of the bacterial isolates were more sensitive to carbapenems than the other antibiotics. The current study showed that antibiotic usage according to the AWaRe classifications was 31.8% in the Access category, 59.5% in the Watch category, and 8.7% in the Reserve category in ICUs of the studied hospitals after the third wave of COVID-19. Conclusions: The findings of the study also highlight the importance and continuous need for the implementation of antibiotic stewardship programs to optimize the appropriate utilization of antibiotics in the ICUs of the studied hospitals.

Evaluation of Moore and grab sampling method for Salmonella Typhi detection in environmental samples in Ghana

BACKGROUND

Typhoid fever causes substantial mortality and morbidity in low and middle-income countries (LMICs) as a result of inadequate water, hygiene, and sanitation facilities. The gold standard for typhoid diagnosis is blood culture, however this method is expensive and mostly unavailable in LMICs. Environmental surveillance (ES) could offer a low cost alternative to identify circulation of Salmonella enterica serovar Typhi (S.Typhi) and help inform public health interventions including vaccination.

METHODS

We implemented standardized protocols for ES at 40 validated sites in peri-urban communities in Ghana from July 2022 to August 2023. Grab samples (GS) and Moore swabs (MS) were collected monthly for the initial 6 months and subsequently monthly MS were maintained for the rest of the study period. Wastewater samples were tested for S. Typhi target genes (ttr, staG, tviB) and a biomarker of human faecal contamination (Bacteroides HF183) using multiplex quantitative PCR (qPCR). Clinical surveillance for typhoid fever was performed by blood culture of febrile cases presenting to the local hospital who lived in the study area.

RESULTS

For the first 6 months of wastewater ES, we observed a higher prevalence of S. Typhi in MS compared to GS [100/240 (42%; 95% Confidence Interval [CI]: 34-50% vs. 24/240 (10%; 95% CI: 6-16%)]; p-value < 0.001]. Overall, the detection of S. Typhi throughout the study period based on MS was 42.1% (202/480; 95% CI: 35-50%). The prevalence of S. Typhi in blood culture surveillance was 0.21% [12/5,576; 95% CI: 0.12-0.38%]. Precipitation (1.1 (95% CI: 1.02-1.10) and number of wet days (2.0 (95%CI: 1.40-2.88) were positively associated with an increased odds of S. Typhi detection in MS and GS.

CONCLUSION

Generally the proportion of S.Typhi detections in wastewater samples was less than blood culture-based detections. Limited detection of confirmed typhoid fever cases at the local hospital may reflect healthcare seeking behaviours, access as well as early treatment with over-the-counter antibiotics. Further work is required to confirm these qPCR detections with amplicon sequencing methods. Strategies also needs to be developed for integration of ES into public health decision making for the prevention of typhoid fever.

Time series data on typhoid fever incidence during outbreaks from 2000 to 2022

This article presents a comprehensive dataset compiling reported cases of typhoid fever from culture-confirmed outbreaks across various geographical locations from 2000 through 2022, categorized into daily, weekly, and monthly time series. The dataset was curated by identifying peer-reviewed epidemiological studies available in PubMed, OVID-Medline, and OVID-Embase. Time-series incidence data were extracted from plots using WebPlotDigitizer, followed by verification of a subset of the dataset. The primary aim of this dataset is to serve as a foundational tool for researchers and policymakers, enabling the development of robust, model-based strategies for the control of typhoid fever outbreaks. The article describes the method by which the dataset has been compiled and how the quality of the data has been verified. Furthermore, it discusses the dataset's potential applications in optimizing vaccination campaigns, improving public health planning, and tailoring interventions to specific epidemiologic contexts. This article contributes significantly to the field of infectious disease modeling, offering a valuable resource for enhancing typhoid fever control measures globally.

A systematic scoping review of antibiotic-resistance in drinking tap water

Environmental matrices have been considered of paramount importance in the spread of antibiotic-resistance; however, the role of drinking waters is still underexplored. Therefore, a scoping review was performed using a systematic approach based on PRISMA guidelines, with the aim of identifying and characterizing antibiotic-resistance in tap water, specifically, water treated at a potabilization plant and provided for drinking use through a water distribution system. The review included 45 studies, the majority of which were conducted in upper-middle-income economies (42.2%), mainly from the Western Pacific region (26.7%), followed by Europe (24.4%). Most of the papers focused on detecting antibiotic-resistant bacteria (ARB), either alone (37.8%) or in combination with antibiotic-resistant genes (ARGs) (26.7%). Multidrug-resistance profile was often identified in heterotrophic bacteria, including various species of nontuberculous mycobacteria, Pseudomonas spp., and Aeromonas spp., which were especially resistant to penicillins, cephalosporins (including 3rd-generation), and also to macrolides (erythromycin) and tetracyclines. Resistance to a wide range of antibiotics was also prevalent in fecal bacteria, e.g., the Enterobacteriaceae family, with common resistance to (fluoro)quinolones and sulfonamide groups. ARGs were investigated either in bacterial strains isolated from tap waters or directly in water samples, and the most frequently detected ARGs belonged to β-lactam, sulfonamide, and tetracycline types. Additionally, mobile genetic elements were found (i.e., int1 and tnpA). Sulfonamides and macrolides were the most frequently detected antibiotics across countries, although their concentrations were generally low (<10 ng/L) in Europe and the United States. From a health perspective, tap water hosted ARB of health concern based on the 2024 WHO bacterial priority pathogens list, mainly Enterobacteriaceae resistant to 3rd-generation cephalosporin and/or carbapenem. Despite the fact that tap water is treated to meet chemical and microbiological quality standards, current evidence suggests that it can harbor antibiotic-resistance determinants, thus supporting its potential role in environmental pathways contributing to antibiotic resistance.

Doripenem, Ertapenem, and Meropenem Sensitivity in Salmonella Typhi: A Cross-Sectional Study From Pakistan

Background Salmonella Typhi (S. Typhi) is increasingly resistant to multiple antibiotics, posing a challenge in treatment, particularly in multidrug-resistant (MDR) cases. Carbapenems, including doripenem, ertapenem, and meropenem, have been considered last-resort options. This study evaluates the effectiveness of these carbapenems against S. Typhi isolates in a clinical setting in Peshawar, Pakistan. Objective To assess the effectiveness of the carbapenem antibiotics, doripenem, ertapenem, and meropenem, against S. Typhi. Methods This study collected data from blood cultures of patients diagnosed with S. Typhi infections at the Hayatabad Medical Complex in Peshawar, Pakistan for two years: from January 1, 2022, to December 31, 2023. Sensitivity testing was performed using the disk diffusion method in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. The analysis examined the sensitivity rates of the three antibiotics and compared their effectiveness. Results A total of 626 S. Typhi isolates were tested. Only 11.98% of the isolates were sensitive to doripenem, while 88.02% were resistant to it. In contrast, 35.5% of the isolates responded to ertapenem, with 64.5% being resistant. Meropenem showed the highest efficacy, with 42.7% of the isolates demonstrating sensitivity. These findings highlight the growing challenge of managing multidrug-resistant (MDR) S. Typhi infections, especially in regions where resistance to carbapenems is becoming prevalent. Conclusion Meropenem proved to be more effective against S. Typhi compared to doripenem and ertapenem. The study emphasizes the need for ongoing monitoring of resistance patterns and the exploration of alternative or combination treatment options. These findings have immediate clinical implications for empiric therapy choices and highlight the urgent need for antibiotic stewardship programs in endemic regions.

5-year vaccine protection following a single dose of Vi-tetanus toxoid conjugate vaccine in Bangladeshi children (TyVOID): a cluster randomised trial

BACKGROUND

WHO currently recommends a single dose of typhoid conjugate vaccine (TCV) in high-burden countries based on 2-year vaccine efficacy data from large randomised controlled trials. Given the decay of immunogenicity, the protection beyond 2 years is unknown. We therefore extended the follow-up of the TyVAC trial in Bangladesh to assess waning of vaccine protection to 5 years after vaccination.

METHODS

We conducted a cluster randomised controlled trial (TyVAC; ISRCTN11643110) in Dhaka, Bangladesh, between 2018 and 2021. Children aged 9 months to 15 years were invited to receive a single dose of TCV or Japanese encephalitis vaccine between April 15, 2018, and November 16, 2019, based on the randomisation of their clusters of residence. Children who received the Japanese encephalitis vaccine were invited to receive TCV at the final visit between Jan 6, and Aug 31, 2021, according to the protocol. This follow-on study extended the follow-up of the original trial until Aug 14, 2023. The primary endpoint of this study was to compare the incidence of blood culture-confirmed typhoid between children who received TCV in 2018-19 (the previous-TCV group) and those who received the vaccine in 2021 (the recent-TCV group), to evaluate the relative decline in vaccine protection. We also did a nested study using the test-negative design comparing the recent-TCV and previous-TCV groups with unvaccinated individuals, as well as an immunogenicity study in a subset of 1500 children.

FINDINGS

Compared with the recent-TCV group, the previous-TCV group had an increased risk of typhoid fever between 2021-23, with an adjusted incidence rate ratio of 3·10 (95% CI 1·53 to 6·29; p<0·0001), indicating a decline in the protection of a single-dose of TCV 3-5 years after vaccination. The extrapolated vaccine effectiveness in years 3-5 was 50% (95% CI -13 to 78), and was validated using the test-negative design analysis, with a vaccine effectiveness of 84% (74 to 90) in the recent-TCV group and 55% (36 to 68) in the previous-TCV group, compared with unvaccinated individuals. Anti-Vi-IgG responses declined over the study period. The highest rate of decay was seen in children vaccinated at younger than 2 years in the original trial. The inverse correlation between age and the decay of antibodies was also seen in the subgroup analysis of vaccine effectiveness, where the youngest age group (<7 years at fever visits) exhibited the fastest waning, with vaccine effectiveness dropping to 24% (95% CI -29 to 55) at 3-5 years after vaccination.

INTERPRETATION

A decline in the protection conferred by a single-dose TCV was observed 3-5 years after vaccination, with the greatest decline in protection and immune responses observed in children vaccinated at younger ages. A booster dose of TCV around school entry age might be needed for children vaccinated while younger than 2 years to sustain protection against typhoid fever during the school years when the risk is the highest.

FUNDING

The Bill & Melinda Gates Foundation.

Combatting extensively drug-resistant Salmonella: a global perspective on outbreaks, impacts, and control strategies

Antibiotic resistance in typhoid fever poses a critical public health problem due to the emergence of extensively drug-resistant (XDR) Salmonella, resulting in prolonged illness and treatment failure. Salmonella enterica serovar Typhi is the most predominant among all serotypes and can acquire resistance. The emergence of XDR Salmonella in various regions globally, particularly Pakistan, presents a concerning trend. However, limited data availability impedes a comprehensive understanding of the outbreaks and hinders the development of real-time solutions. Here, we have provided an updated overview of the current outbreaks of XDR Salmonella in epidemic and endemic regions. Treatments of XDR Salmonella infections are challenging, as there are records of treatment failure in humans and animals. However, intensive prevention techniques can be implemented pending the advent of novel antibiotics. Emphasis on antimicrobial stewardship and frequent surveillance of the pathogen should be made to keep track of potential outbreaks in both human and animal populations. Although progress is being made to combat XDR Salmonella within some regions, a unified and efficient effort on an international scale is required to curtail the XDR outbreak before it escalates and leads us back to the pre-antibiotic era.

Global patterns of syphilis, gonococcal infection, typhoid fever, paratyphoid fever, diphtheria, pertussis, tetanus, and leprosy from 1990 to 2021: findings from the Global Burden of Disease Study 2021

BACKGROUND

Certain infectious diseases are caused by specific bacterial pathogens, including syphilis, gonorrhea, typhoid and paratyphoid fever, diphtheria, pertussis, tetanus, leprosy, and tuberculosis. These diseases significantly impact global health, contributing heavily to the disease burden. The study aims to thoroughly evaluate the global burden of syphilis, gonorrhea, typhoid and paratyphoid fever, diphtheria, pertussis, tetanus, and leprosy.

METHODS

Leveraging the Global Burden of Disease (GBD) study 2021, age-specific and Socio-demographic Index (SDI)-specific incidence, disability-adjusted life-years (DALYs), and death for eight specific bacterial infections across 204 countries and territories from 1990 to 2021 were analyzed. Percentage changes in age-standardized incidence rate (ASIR), DALY rate, and mortality rate (ASMR) were also examined, with a focus on disease distribution across different regions, age groups, genders, and SDI.

RESULTS

By 2021, among the eight diseases, gonococcal infection had the highest global ASIR [1096.58 per 100,000 population, 95% uncertainty interval (UI): 838.70, 1385.47 per 100,000 population], and syphilis had the highest global age-standardized DALY rate (107.13 per 100,000 population, 95% UI: 41.77, 212.12 per 100,000 population). Except for syphilis and gonococcal infection, the age-standardized DALY rate of the remaining diseases decreased by at least 55% compared to 1990, with tetanus showing the largest decrease by at least 90%. Globally, significant declines in the ASIR, age-standardized DALY rate, and ASMR for these eight bacterial infections have been observed in association with increases in the SDI. Regions with lower SDI, such as sub-Saharan Africa, experienced a relatively higher burden of these eight bacterial infections.

CONCLUSIONS

Although there has been an overall decline in these eight diseases, they continue to pose significant public health challenges, particularly in low SDI regions. To further reduce this burden in these areas, targeted intervention strategies are essential, including multi-sectoral collaboration, policy support, improved WASH management, and enhanced research efforts.

Unveiling a Comprehensive Multi-epitope Subunit Vaccine Strategy Against Salmonella subsp. enterica: Bridging Core, Subtractive Proteomics, and Immunoinformatics

Salmonella subsp. enterica (SE) presents a significant global health challenge in both developed and developing countries. Current SE vaccines have limitations, targeting specific strains and demonstrating moderate efficacy in adults, while also being unsuitable for young children and often unaffordable in regions with lower income levels where the disease is prevalent. To address these challenges, this study employed a computational approach integrating core proteomics, subtractive proteomics, and immunoinformatics to develop a universal SE vaccine and identify potential drug targets. Analysis of the core proteome of 185 SE strains revealed 1964 conserved proteins. Subtractive proteomics identified 9 proteins as potential vaccine candidates and 41 as novel drug targets. Using reverse vaccinology-based immunoinformatics, four multi-epitope-based subunit vaccine constructs (MESVCs) were designed, aiming to stimulate cytotoxic T lymphocyte, helper T lymphocyte, and linear B lymphocyte responses. These constructs underwent comprehensive evaluations for antigenicity, immunogenicity, toxicity, hydropathicity, and physicochemical properties. Predictive modeling, refinement, and validation were conducted to determine the secondary and tertiary structures of the SE-MESVCs, followed by docking studies with MHC-I, MHC-II, and TLR4 receptors. Molecular docking assessments showed favorable binding with all three receptors, with SE-MESVC-4 exhibiting the most promising binding energy. Molecular dynamics simulations confirmed the binding affinity and stability of SE-MESVC-4 with the TLR4/MD2 complex. Additionally, codon optimization and in silico cloning verified the efficient translation and successful expression of SE-MESVC-4 in Escherichia coli (E. coli) str. K12. Subsequent in silico immune simulation evaluated the efficacy of SE-MESVC-4 in triggering an effective immune response. These results suggest that SE-MESVC-4 may induce both humoral and cellular immune responses, making it a potential candidate for an effective SE vaccine. However, further experimental investigations are necessary to validate the immunogenicity and efficacy of SE-MESVC-4, bringing us closer to effectively combating SE infections.

Exploring the Antimicrobial Resistance Profile of Salmonella typhi and Its Clinical Burden

Background: Typhoid fever caused by Salmonella enterica serovar Typhi (S. typhi) continues to pose a significant risk to public health in developing countries, including Pakistan. This study investigated the epidemiological factors linked to suspected and confirmed S. typhi infections in Peshawar's hospital population. Methodology: A total of 5735 blood samples of patients with suspected enteric fever were collected from September 2022 to November 2023. S. typhi infection was confirmed using microbiological culture of blood samples, biochemical-based tests, and DNA-sequencing methods. Drug sensitivity testing on cultures was conducted as per the CLSI guidelines. Chi-square tests were used to analyze the clinical and epidemiologic characteristics of 5735 samples stratified by S. typhi infection status, and risk factors were assessed by applying logistic regression models to estimate odds ratios (ORs). Results: The number of confirmed typhoid fever cases in this hospital-based study population was 691 (/5735, 12.0%), more prevalent in males (447/3235 13.8%) and children (0-11 years) (429/2747, 15.6%). Compared to children, the risk of S. typhi infection was lower in adolescence (adjusted OR = 0.52; 95% CI: 0.42-0.66), adulthood (19-59 years; aOR = 0.30; 95% CI: 0.25-0.38), and older adulthood (aOR = 0.08; 95% CI: 0.04-0.18) (p < 0.001). Compared to males, the risk of S. typhi infection was lower in females (aOR = 0.67; 95% CI = 0.56-0.80; p = 0.002). Living in a rural residence (compared to urban) was associated with a higher risk of infection (aOR = 1.38; 95% CI: 1.16-1.63; p = 0.001), while access to a groundwater source (compared to municipal water supply) led to a lower risk (aOR = 0.56; 95% CI: 0.43-0.73; p = 0.002). Vaccination demonstrated a robust protective effect (aOR = 0.069; 95% CI = 0.04-0.11, p = 0.002). For those with typhoid infections, clinical biomarker analysis revealed the presence of leucopenia (65/691, 9.4%), thrombocytopenia (130/691, 18.8%), and elevated alanine aminotransferase (ALT) (402/691, 58.2%) and C-reactive protein (CRP) (690/691, 99.9%) levels. Worryingly, among the positive S. typhi isolates, there was a high prevalence of drug resistance (653/691), including multidrug-resistant (MDR 82/691, 11.9%) and extensively drug-resistant types (XDR, 571/691, 82.6%). Conclusions: This study highlights the importance of age, sex, locality, water source, and vaccination status in shaping the epidemiological landscape of S. typhi in the Peshawar district. It implies that expanding vaccination coverage to the broader population of Khyber Pakhtunkhwa province, particularly in the district of Peshawar, would be beneficial.

Effectiveness of Oral Azithromycin in Treating Enteric Fever: A Hospital-Based Study on Pediatric Patients

Introduction Enteric fever is prevalent in underdeveloped and developing countries. It is caused by Salmonella Typhi, which has developed resistance over the years to commonly used antimicrobials. Meropenem is an effective treatment for all complicated and uncomplicated extensively drug-resistant (XDR) bacteria, but it is administered intravenously, three times daily, by infusion, and it is quite expensive for the patient. Oral azithromycin is shown by some authors to be effective in extensively drug-resistant enteric fever. Material and methods This retrospective cross-sectional study was conducted in the outpatient department of Lady Reading Hospital Medical Teaching Institution, Peshawar. The duration of the study was one year. Data was collected after approval from the hospital's Ethical and Research Committee. All pediatric patients meeting the inclusion criteria for extensively drug-resistant enteric fever were included. Data on patient demographics, blood culture and laboratory results, treatment given, and effectiveness were documented in a specialized proforma. Statistical Package for Social Sciences (SPSS) version 23 (IBM Corp., Armonk, NY, US) was used for data analysis. Results Out of the total 106 patients, 72 (67.9%) were male and 34 (32.1%) were female. The mean age was 7.51 ± 2.75 years, with a range of 1 to 15 years. Among them, 66 (62.3%) had anemia (hemoglobin less than 11 grams per deciliter for under 5 years and 11.5 for 5-15 years old children), with a mean hemoglobin level of 10.6 ± 1.53 grams per deciliter (g/dl), ranging from 7.2 to 13.8 g/dl. Thrombocytopenia was found in 14 (13%) patients. The mean platelet count was 317 x 103 ± 164 cells per microliter, with a range of 61 x 103 to 834 x 103 cells per liter. The mean total leukocyte count was 9.71x 103 ± 4.321 cells per microliter, with a range of 2.01 x 103 to 30.40 x103 cells per microliter. However, leucopenia was seen in only 5 (4.7%) patients. In 98.1% of cases, azithromycin was found to be effective in treating enteric fever caused by extensively drug-resistant Salmonella. Conclusion Azithromycin is effective in treating extensively drug-resistant enteric fever. It can be confidently used in patients with no or mild complications with extensively drug-resistant enteric fever. Good compliance and complete dosage should be followed to avoid resistance to this drug. Blood cultures should always be sent when prescribing antibiotics, especially when suspecting enteric fever.

Levofloxacin loaded chitosan and poly-lactic-co-glycolic acid nano-particles against resistant bacteria: Synthesis, characterization and antibacterial activity

BACKGROUND

With the global increase in antibacterial resistance, the challenge faced by developing countries is to utilize the available antibiotics, alone or in combination, against resistant bacterial strains. We aimed to encapsulate the levofloxacin (LVX) into polymeric nanoparticles using biodegradable polymers i.e. Chitosan and PLGA, estimating their physicochemical characteristics followed by functional assessment as nanocarriers of levofloxacin against the different resistant strains of bacteria isolated from biological samples collected from tertiary care hospital in Lahore, Pakistan.

METHODS

LVX-NPs were synthesized using ion gelation and double emulsion solvent-evaporation method employing chitosan (CS) and poly-lactic-co-glycolic acid (PLGA), characterized via FTIR, XRD, SEM, and invitro drug release studies, while antibacterial activity was assessed using Kirby-Bauer disc-diffusion method.

RESULTS

Data revealed that the levofloxacin-loaded chitosan nanoparticles showed entrapment efficiency of 57.14% ± 0.03 (CS-I), 77.30% ± 0.08(CS-II) and 87.47% ± 0.08 (CS-III). The drug content, particle size, and polydispersity index of CS-I were 52.22% ± 0.2, 559 nm ± 31 nm, and 0.030, respectively, whereas it was 66.86% ± 0.17, 595 nm ± 52.3 nm and 0.057, respectively for CS-II and 82.65% ± 0.36, 758 nm ± 24 nm and 0.1, respectively for CS-III. The PLGA-levofloxacin nanoparticles showed an entrapment efficiency of 42.80% ± 0.4 (PLGA I) and 23.80% ± 0.4 (PLGA II). The drug content, particle size and polydispersity index of PLGA-I were 86% ± 0.21, 92 nm ± 10 nm, and 0.058, respectively, whereas it was 52.41% ± 0.45, 313 nm ± 32 nm and 0.076, respectively for PLGA-II. The XRD patterns of both polymeric nanoparticles showed an amorphous nature. SEM analysis reflects the circular-shaped agglomerated nanoparticles with PLGA polymer and dense spherical nanoparticles with chitosan polymer. The in-vitro release profile of PLGA-I nanoparticles showed a sustained release of 82% in 120 h and it was 58.40% for CS-III. Both types of polymeric nanoparticles were found to be stable for up to 6 months without losing any major drug content. Among the selected formulations, CS-III and PLGA-I, CS-III had better antibacterial potency against gram+ve and gram-ve bacteria, except for K. pneumonia, yet, PLGA-I demonstrated efficacy against K. pneumonia as per CSLI guidelines. All formulations did not exhibit any signs of hemotoxicity, nonetheless, the CS-NPs tend to bind on the surface of RBCs.

CONCLUSION

These data suggested that available antibiotics can effectively be utilized as nano-antibiotics against resistant bacterial strains, causing severe infections, for improved antibiotic sensitivity without compromising patient safety.

The impact of antibiotic resistance on the rampant spread of infectious diseases in Pakistan: Insights from a narrative review

Background and Aims

Antibiotic resistance (ABR) is a global public health emergency which has seen an uptick in low- to middle-income countries in recent times due to a plethora of aggravating factors and has led to a whole host of setting-specific pathogens registering high rates of resistance, causing outbreaks with graver mortality and morbidity. This review analyzes available literature to determine the causes and effects of ABR and recommend solutions to the problem in a Pakistani setting.

Methods

Sources for this narrative review were identified via electronic databases using keyword search methods. The information was retrieved using databases such as PubMed and Science Direct. Additionally, websites such as CDC and World Health Organization were used to attain pertinent information. All the sources were selected as per their relevance and appropriateness toward the purpose of this review.

Results

This review details the causes by dividing them into three primary strata, namely (1) under-regulation, (2) over-prescription and self-medication, and (3) lack of medical stewardship. This is made much graver when the COVID-19 pandemic and the subsequent erratic treatment response is considered, with the pandemic augmenting already high levels of consumption. These factors have led a cascade of effects including, but not limited to, a considerable increase in ABR in pathogens to first-line drugs.

Conclusion

ABR is a serious and growing issue which will result in undesirable personal, local, and national consequences if unchecked. Mitigation and reversal of this trend is necessary by developing existing programs and investing in novel therapies and pharmaceutical research and strengthening regulatory policies and mechanisms.

Quantitative microbial risk assessment for ingestion of antibiotic resistance genes from private wells contaminated by human and livestock fecal sources

We used quantitative microbial risk assessment to estimate ingestion risk for intI1, erm(B), sul1, tet(A), tet(W), and tet(X) in private wells contaminated by human and/or livestock feces. Genes were quantified with five human-specific and six bovine-specific microbial source-tracking (MST) markers in 138 well-water samples from a rural Wisconsin county. Daily ingestion risk (probability of swallowing ≥1 gene) was based on daily water consumption and a Poisson exposure model. Calculations were stratified by MST source and soil depth over the aquifer where wells were drilled. Relative ingestion risk was estimated using wells with no MST detections and >6.1 m soil depth as a referent category. Daily ingestion risk varied from 0 to 8.8 × 10-1 by gene and fecal source (i.e., human or bovine). The estimated number of residents ingesting target genes from private wells varied from 910 (tet(A)) to 1,500 (intI1 and tet(X)) per day out of 12,000 total. Relative risk of tet(A) ingestion was significantly higher in wells with MST markers detected, including wells with ≤6.1 m soil depth contaminated by bovine markers (2.2 [90% CI: 1.1-4.7]), wells with >6.1 m soil depth contaminated by bovine markers (1.8 [1.002-3.9]), and wells with ≤6.1 m soil depth contaminated by bovine and human markers simultaneously (3.1 [1.7-6.5]). Antibiotic resistance genes (ARGs) were not necessarily present in viable microorganisms, and ingestion is not directly associated with infection. However, results illustrate relative contributions of human and livestock fecal sources to ARG exposure and highlight rural groundwater as a significant point of exposure.IMPORTANCEAntibiotic resistance is a global public health challenge with well-known environmental dimensions, but quantitative analyses of the roles played by various natural environments in transmission of antibiotic resistance are lacking, particularly for drinking water. This study assesses risk of ingestion for several antibiotic resistance genes (ARGs) and the class 1 integron gene (intI1) in drinking water from private wells in a rural area of northeast Wisconsin, United States. Results allow comparison of drinking water as an exposure route for antibiotic resistance relative to other routes like food and recreational water. They also enable a comparison of the importance of human versus livestock fecal sources in the study area. Our study demonstrates the previously unrecognized importance of untreated rural drinking water as an exposure route for antibiotic resistance and identifies bovine fecal material as an important exposure factor in the study setting.

Punicalagin, a pomegranate polyphenol sensitizes the activity of antibiotics against three MDR pathogens of the Enterobacteriaceae

BACKGROUND

Multidrug resistance (MDR) in the family Enterobacteriaceae is a perniciously increasing threat to global health security. The discovery of new antimicrobials having the reversing drug resistance potential may contribute to augment and revive the antibiotic arsenal in hand. This study aimed to explore the anti-Enterobacteriaceae capability of bioactive polyphenols from Punica granatum (P. granatum) and their co-action with antibiotics against clinical isolates of Enterobacteriaceae predominantly prevalent in South Asian countries.

METHODS

The Kandhari P. granatum (Pakistani origin) extracts were tested for anti-Enterobacteriaceae activity by agar well diffusion assay against MDR Salmonella enterica serovar Typhi, serovar Typhimurium and Escherichia coli. Predominant compounds of active extract were determined by mass spectrometry and screened for bioactivity by agar well diffusion and minimum inhibitory concentration (MIC) assay. The active punicalagin was further evaluated at sub-inhibitory concentrations (SICs) for coactivity with nine conventional antimicrobials using a disc diffusion assay followed by time-kill experiments that proceeded with SICs of punicalagin and antimicrobials.

RESULTS

Among all P. granatum crude extracts, pomegranate peel methanol extract showed the largest inhibition zones of 25, 22 and 19 mm, and the MICs as 3.9, 7.8 and 7.8 mg/mL for S. typhi, S. typhimurium and E. coli, respectively. Punicalagin and ellagic acid were determined as predominant compounds by mass spectrometry. In plate assay, punicalagin (10 mg/mL) was active with hazy inhibition zones of 17, 14, and 13 mm against S. typhi, S. typhimurium and E. coli, respectively. However, in broth dilution assay punicalagin showed no MIC up to 10 mg/mL. The SICs 30 μg, 100 μg, and 500 μg of punicalagin combined with antimicrobials i.e., aminoglycoside, β-lactam, and fluoroquinolone act in synergy against MDR strains with % increase in inhibition zone values varying from 3.4 ± 2.7% to 73.8 ± 8.4%. In time-kill curves, a significant decrease in cell density was observed with the SICs of antimicrobials/punicalagin (0.03-60 μg/mL/30, 100, 500 μg/mL of punicalagin) combinations.

CONCLUSIONS

The P. granatum peel methanol extract exhibited antimicrobial activity against MDR Enterobacteriaceae pathogens. Punicalagin, the bacteriostatic flavonoid act as a concentration-dependent sensitizing agent for antimicrobials against Enterobacteriaceae. Our findings for the therapeutic punicalagin-antimicrobial combination prompt further evaluation of punicalagin as a potent activator for drugs, which otherwise remain less or inactive against MDR strains.

Antimicrobial resistance containment in Africa: Moving beyond surveillance

Worldwide, infections caused by drug-resistant pathogens constitute a significant challenge threatening therapeutic efforts. According to the World Health Organization (WHO), antimicrobial resistance (AMR) ranks among the top 10 global public health threats. Organisms with a high rate of multiple host adaptivity, significant genetic diversity (multiple lineages), high virulence factors, and genetic exchange have been isolated from various sources (humans, animals, and the environment) even without exposure to prior antibiotics. Till now, the source of AMR and how resistant clones are selected in the environment remain largely elusive, and potential anthropogenic transmission has been reported in different studies. Various drug-resistant pathogens, lineages, resistant clones, outbreak clusters, plasmid replicates, and genes that play a critical role in resistance dissemination have been identified. Maintenance of certain multidrug-resistant (MDR) determinants has also been shown to enhance or support the propagation of MDR. So far, significant advances have been made in understanding the burden of AMR. However, overcoming AMR requires a holistic approach, as there is no single approach with sufficient precision to curb the threat. While strengthening AMR surveillance efforts is essential, as we have shown, there is also a need to intensify efforts to strengthen therapeutic interventions, especially in priority regions such as Africa. Herein, we discussed the burden of AMR and the dissemination of AMR in humans, animals, and the environment (non-medical drivers). We further delved into the big questions on Africa and discussed how therapeutic interventions involving vaccines and other viable biomaterials could be pivotal in reducing the burden of AMR to the barest minimum.

An insights into emerging trends to control the threats of antimicrobial resistance (AMR): an address to public health risks

Antimicrobial agents are used to treat microbial ailments, but increased use of antibiotics and exposure to infections in healthcare facilities and hospitals as well as the excessive and inappropriate use of antibiotics at the society level lead to the emergence of multidrug-resistant (MDR) bacteria. Antimicrobial resistance (AMR) is considered a public health concern and has rendered the treatment of different infections more challenging. The bacterial strains develop resistance against antimicrobial agents by limiting intracellular drug accumulation (increasing efflux or decreasing influx of antibiotics), modification and inactivation of drugs and its targets, enzymatic inhibition, and biofilm formation. However, the driving factors of AMR include the sociocultural and economic circumstances of a country, the use of falsified and substandard medicines, the use of antibiotics in farm animals, and food processing technologies. These factors make AMR one of the major menaces faced by mankind. In order to promote reciprocal learning, this article summarizes the current AMR situation in Pakistan and how it interacts with the health issues related to the COVID-19 pandemic. The COVID-19 pandemic aids in illuminating the possible long-term impacts of AMR, which are less immediate but not less severe since their measures and effects are equivalent. Impact on other sectors, including the health industry, the economy, and trade are also discussed. We conclude by summarizing the several approaches that could be used to address this issue.

Regional and National Trends in Consumption of Antimicrobials in Pakistan; Pre and Post-COVID (2019-2021)

BACKGROUND

Efforts to combat antimicrobial resistance, a growing public health problem in Pakistan, have been hampered by the lack of high-quality national and provincial-level antimicrobial consumption data. The singular objective of this retrospective study was to measure antimicrobial consumption over 3 years between 2019 and 2021.

METHODS

The study was designed to estimate antimicrobial consumption at National and Regional levels. Antimicrobial consumption data was collected by IQVIA covering 110 districts of Pakistan in which 88% of sales are census (accurate sales collected directly from distributors), whereas 12% of sales (sales of 300 pharmacies) are projected on the national level. To determine the usage for 3 consecutive years, the consumption of antibiotics was calculated as defined daily doses (DDD) of antibiotics per 1000 inhabitants per day (DID).

RESULTS

The results of our study demonstrated a steep increase in the consumption of antimicrobials from 2019 to 2021. An increase in consumption of most classes of antibiotics was observed both nationally and Regionally. Quinolones, penicillins (co-amoxiclav), macrolides, and third-generation cephalosporins remained the most frequently used antibiotics nationally. A 40% increase in intravenous use of antimicrobials was observed between 2019 and 2021 at the national level. Moxifloxacin, Levofloxacin, Ciprofloxacin, and linezolid were the most commonly used intravenous antibiotics. Region 7 (Peshawar) demonstrated the highest consumption, followed by Region 1 (Karachi) and Region 6 (Faisalabad). Among the most commonly used antibiotics, the use of third-generation cephalosporin (cefixime), quinolones, penicillins (amoxicillin + clavulanic acid), and macrolides (azithromycin) was most noticeable in all regions, particularly in those with the higher consumption of antibiotics.

CONCLUSIONS

Although the increase in consumption of all antibiotics is concerning, the steep increase in the use of watch and reserve category antibiotics during the study period calls for immediate actions to limit and regulate their usage.

Typhoid fever

Typhoid fever is an invasive bacterial disease associated with bloodstream infection that causes a high burden of disease in Africa and Asia. Typhoid primarily affects individuals ranging from infants through to young adults. The causative organism, Salmonella enterica subsp. enterica serovar Typhi is transmitted via the faecal-oral route, crossing the intestinal epithelium and disseminating to systemic and intracellular sites, causing an undifferentiated febrile illness. Blood culture remains the practical reference standard for diagnosis of typhoid fever, where culture testing is available, but novel diagnostic modalities are an important priority under investigation. Since 2017, remarkable progress has been made in defining the global burden of both typhoid fever and antimicrobial resistance; in understanding disease pathogenesis and immunological protection through the use of controlled human infection; and in advancing effective vaccination programmes through strategic multipartner collaboration and targeted clinical trials in multiple high-incidence priority settings. This Primer thus offers a timely update of progress and perspective on future priorities for the global scientific community.

Genomic analysis of almost 8,000 Salmonella genomes reveals drivers and landscape of antimicrobial resistance in China

IMPORTANCE

We established the largest Salmonella genome database from China and presented the landscape and spatiotemporal dynamics of antimicrobial resistance genes. We also found that economic, climatic, and social factors can drive the rise of antimicrobial resistance. The Chinese local Salmonella genome database version 2 was released as an open-access database (https://nmdc.cn/clsgdbv2) and thus can assist surveillance studies across the globe. This database will help inform interventions for AMR, food safety, and public health.

Antibiotics resistance as a major public health concern: A pharmaco-epidemiological study to evaluate prevalence and antibiotics susceptibility-resistance pattern of bacterial isolates from multiple teaching hospitals

BACKGROUND

Multi Drugs Resistance (MDR) is among the most worrisome healthcare issues resulting from inappropriate and indiscriminate utilization of antimicrobial agents which has compromised the efficacy and reliability of antimicrobial agents (AMAs). This has not only put a huge burden on the health care system but also is a major cause of morbidity and mortality. This project was designed to evaluate the prevalence of various microbial strains among patients admitted to various teaching hospitals and to assess their susceptibility and resistance towards clinically approved antibiotics.

METHODS

The study was conducted during August 2021-February 2022 to determine the prevalence of common resistant strains of bacteria and to analyze their susceptibility pattern to the commonly prescribed antibiotics using standard procedures. One hundred and thirty biological samples including urine, blood, cerebrospinal fluid (CSF), wound swabs, pus and sputum were collected from the site of infection from the patients admitted at different wards of North West General Hospital (NWGH), Peshawar, Pakistan, Khyber Teaching Hospital (KTH), Peshawar Pakistan, and Hayat Abad Medical Complex (HMC) Peshawar Pakistan. Samples were collected and cultured following standard hospital procedures. The cultured samples were subjected to identification procedures including Gram staining, morphological characterization of bacterial colonies and biochemical assessments. The identified bacteria were tested for their susceptibility using Kirby-Bauer disc diffusion method. The diameter of Inhibitory Zones (DIZ) was analyzed following Clinical and Laboratory Standards Institute (CLSI) criteria. Minimum Inhibitory Concentrations (MICs) were evaluated using agar dilution method. Antimicrobials sensitivity were presented as antibiogram following CLSI M39 standard.

RESULTS

A total of one hundred and thirty biological samples were collected, out of which one hundred and nine samples were positive for bacterial growth and were further processed for detailed analysis. The frequency and type of bacteria isolated from various cultures indicated that Gram negative bacteria (n = 92/109) were more dominant than Gram-positive (n = 17/109) pathogens. The most prevalent bacteria isolated was Escherichia coli (29.35 %), followed by Staphylococcus aureus (15.59 %), and Klebsiella spp, (12.84 %). In addition, other pathogens including, Enterobacter spp, Citrobacter spp, and Acinetobacter spp. showed a prevalence of 9.175 %, 8.25 %, and 5.50 % respectively. As indicated in the antbiogram, several organisms exhibited considerble decline in the sensitivies towards various antibiotics. A high percentage of resistance was observed against some antibiotics including trimethoprim, co-trimoxazole, amoxicillin/clavulanate, ciprofloxacin, piperacillin/tazobactam, cefotaxime and ceftazidime.

CONCLUSION

The prevalence of resistant strains of pathogens is increasing day by day, while the antibiotics commonly prescribed against them are losing their efficacy, which is pushing the world to the era of pre-antibiotics. Unfortunately, the discovery of novel antibiotics is limited and researchers speculate that the is pushing towards pre-antibiotics era. Subsequently, efforts must be directed towards ensuring rational antibiotics use to prevent emergence of MDR pathogens. Our findings indicated that Gram negative bacteria including Escherichia coli was most prevalent. Other bacterial strains including S. aureus, Klebsiella spp, Enterobacter spp, Citrobacter spp, and Acinetobacter spp. were found among the causative agents. Unfortunately, considerable decline in the sensitivities of various bacterial isolated were observed towards the tested antibiotics. Previous studies reported the high prevalence of E. coli and S. aureus in clinical samples of Pakistani hospitals including hospitals in Peshawar and thus our findings are in agreement with the previous reports. Pharmacists being experts can play their role by promoting the optimal use of antimicrobial agents and educating healthcare professionals, patients and the public.

Empowering Low- and Middle-Income Countries to Combat AMR by Minimal Use of Antibiotics: A Way Forward

Antibiotic overuse poses a critical global health concern, especially in low- and middle-income countries (LMICs) where access to quality healthcare and effective regulatory frameworks often fall short. This issue necessitates a thorough examination of the factors contributing to antibiotic overuse in LMICs, including weak healthcare infrastructure, limited access to quality services, and deficiencies in diagnostic capabilities. To address these challenges, regulatory frameworks should be implemented to restrict non-prescription sales, and accessible point-of-care diagnostic tools must be emphasized. Furthermore, the establishment of effective stewardship programs, the expanded use of vaccines, and the promotion of health systems, hygiene, and sanitation are all crucial components in combating antibiotic overuse. A comprehensive approach that involves collaboration among healthcare professionals, policymakers, researchers, and educators is essential for success. Improving healthcare infrastructure, enhancing access to quality services, and strengthening diagnostic capabilities are paramount. Equally important are education and awareness initiatives to promote responsible antibiotic use, the implementation of regulatory measures, the wider utilization of vaccines, and international cooperation to tackle the challenges of antibiotic overuse in LMICs.

South Asian Transplant Infectious Disease Guidelines for Solid Organ Transplant Candidates, Recipients, and Donors

These guidelines discuss the epidemiology, screening, diagnosis, posttransplant prophylaxis, monitoring, and management of endemic infections in solid organ transplant (SOT) candidates, recipients, and donors in South Asia. The guidelines also provide recommendations for SOT recipients traveling to this region. These guidelines are based on literature review and expert opinion by transplant physicians, surgeons, and infectious diseases specialists, mostly from South Asian countries (India, Pakistan, Bangladesh, Nepal, and Sri Lanka) as well as transplant experts from other countries. These guidelines cover relevant endemic bacterial infections (tuberculosis, leptospirosis, melioidosis, typhoid, scrub typhus), viral infections (hepatitis A, B, C, D, and E; rabies; and the arboviruses including dengue, chikungunya, Zika, Japanese encephalitis), endemic fungal infections (mucormycosis, histoplasmosis, talaromycosis, sporotrichosis), and endemic parasitic infections (malaria, leishmaniasis, toxoplasmosis, cryptosporidiosis, strongyloidiasis, and filariasis) as well as travelers' diarrhea and vaccination for SOT candidates and recipients including travelers visiting this region. These guidelines are intended to be an overview of each topic; more detailed reviews are being published as a special supplement in the Indian Journal of Transplantation .

Associations of water, sanitation, and hygiene with typhoid fever in case-control studies: a systematic review and meta-analysis

BACKGROUND

Water, sanitation, and hygiene (WASH) play a pivotal role in controlling typhoid fever, as it is primarily transmitted through oral-fecal pathways. Given our constrained resources, staying current with the most recent research is crucial. This ensures we remain informed about practical insights regarding effective typhoid fever control strategies across various WASH components. We conducted a systematic review and meta-analysis of case-control studies to estimate the associations of water, sanitation, and hygiene exposures with typhoid fever.

METHODS

We updated the previous review conducted by Brockett et al. We included new findings published between June 2018 and October 2022 in Web of Science, Embase, and PubMed. We used the Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tool for risk of bias (ROB) assessment. We classified WASH exposures according to the classification provided by the WHO/UNICEF Joint Monitoring Programme for Water Supply, Sanitation, and Hygiene (JMP) update in 2015. We conducted the meta-analyses by only including studies that did not have a critical ROB in both Bayesian and frequentist random-effects models.

RESULTS

We identified 8 new studies and analyzed 27 studies in total. Our analyses showed that while the general insights on the protective (or harmful) impact of improved (or unimproved) WASH remain the same, the pooled estimates of OR differed. Pooled estimates of limited hygiene (OR = 2.26, 95% CrI: 1.38 to 3.64), untreated water (OR = 1.96, 95% CrI: 1.28 to 3.27) and surface water (OR = 2.14, 95% CrI: 1.03 to 4.06) showed 3% increase, 18% decrease, and 16% increase, respectively, from the existing estimates. On the other hand, improved WASH reduced the odds of typhoid fever with pooled estimates for improved water source (OR = 0.54, 95% CrI: 0.31 to 1.08), basic hygiene (OR = 0.6, 95% CrI: 0.38 to 0.97) and treated water (OR = 0.54, 95% CrI: 0.36 to 0.8) showing 26% decrease, 15% increase, and 8% decrease, respectively, from the existing estimates.

CONCLUSIONS

The updated pooled estimates of ORs for the association of WASH with typhoid fever showed clear changes from the existing estimates. Our study affirms that relatively low-cost WASH strategies such as basic hygiene or water treatment can be an effective tool to provide protection against typhoid fever in addition to other resource-intensive ways to improve WASH.

TRIAL REGISTRATION

PROSPERO 2021 CRD42021271881.

How can we tackle the overuse of antibiotics in low- and middle-income countries?

INTRODUCTION

Antibiotic overuse is a pressing global health concern, particularly in low- and middle-income countries (LMICs) where there is limited access to quality healthcare and insufficient regulation of antibiotic dispensation. This perspective piece highlights the challenges of antibiotic overuse in LMICs and provides insights into potential solutions to address this issue.

AREAS COVERED

This perspective explores key factors contributing to antibiotic overuse in LMICs, encompassing weak healthcare infrastructure, limited access to quality services, and deficiencies in diagnostic capabilities. It discusses regulatory frameworks to curb non-prescription sales, the role of accessible point-of-care diagnostic tools, challenges in implementing effective stewardship programs, the expanded use of vaccines, and the importance of health systems, hygiene, and sanitation.

EXPERT OPINION

In this article, we emphasize the need for a comprehensive approach involving collaboration among healthcare professionals, policymakers, researchers, and educators. We underscore the importance of improving healthcare infrastructure, enhancing access to quality services, and strengthening diagnostic capabilities. The article also highlights the significance of education and awareness in promoting responsible antibiotic use, the role of regulatory measures, the expanded utilization of vaccines, and the need for international collaboration to address the challenges of antibiotic overuse in LMICs.

Salmonella Combination Vaccines: Moving Beyond Typhoid

There is now a robust pipeline of licensed and World Health Organization (WHO)-prequalified typhoid conjugate vaccines with a steady progression of national introductions. However, typhoid fever is responsible for less than half the total global burden of Salmonella disease, and even less among children aged <5 years. Invasive nontyphoidal Salmonella disease is the dominant clinical presentation of Salmonella in Africa, and over a quarter of enteric fever in Asia is due to paratyphoid A. In this article, we explore the case for combination Salmonella vaccines, review the current pipeline of these vaccines, and discuss key considerations for their development, including geographies of use, age of administration, and pathways to licensure. While a trivalent typhoid/nontyphoidal Salmonella vaccine is attractive for Africa, and a bivalent enteric fever vaccine for Asia, a quadrivalent vaccine covering the 4 main disease-causing serovars of Salmonella enterica would provide a single vaccine option for global Salmonella coverage.

What Should We Be Recommending for the Treatment of Enteric Fever?

Patients with suspected enteric (typhoid and paratyphoid) fever are predominantly managed as outpatients in endemic regions. Nonspecific clinical presentation, lack of accurate diagnostic tools, and widespread antimicrobial resistance makes management challenging. Resistance has been described for all antimicrobials including chloramphenicol, amoxycillin, trimethoprim-sulfamethoxazole, ciprofloxacin, ceftriaxone, and azithromycin. No significant differences have been demonstrated between these antimicrobials in their ability to treat enteric fever in systematic reviews of randomized controlled trials (RCTs). Antimicrobial choice should be guided by local resistance patterns and national guidance. Extensively drug-resistant typhoid isolates require treatment with azithromycin and/or meropenem. Combining antimicrobials that target intracellular and extracellular typhoid bacteria is a strategy being explored in the Azithromycin and Cefixime in Typhoid Fever (ACT-SA) RCT, in progress in South Asia. Alternative antimicrobials, such as the oral carbapenem, tebipenem, need clinical evaluation. There is a paucity of evidence to guide the antimicrobial management of chronic fecal carriers.

Immune responses in children after vaccination with a typhoid Vi-tetanus toxoid conjugate vaccine in Bangladesh

A cluster-randomized trial of Vi-TT was conducted in Dhaka, Bangladesh, using JE vaccine as the control. A subset of 1,500 children were randomly selected on 2:1 basis (Vi-TT vs JE) to assess immune response. Blood was collected before vaccination, and on days 28, 545 and 730 post-vaccination and plasma anti-Vi-IgG response was measured. A robust, persistent antibody response was induced after single dose of Vi-TT, even after 2 years of vaccination. While there is no accepted serological antibody threshold of protection, analyzing the antibodies of children who received Vi-TT provides evidence that may later be useful in predicting population protection.

Assessment of knowledge, perception, practices and drivers of antimicrobial resistance and antimicrobial usage among veterinarians in Pakistan

BACKGROUND

Antimicrobial resistance (AMR) and irrational antimicrobial usage (AMU) are a global problem, particularly evident in low- and middle-income countries including Pakistan. Our study aimed to assess the knowledge, attitudes and prescribing practices (KAP) of field veterinarians regarding AMR and AMU.

METHODS

A questionnaire-based online survey was conducted using Google forms to collect data on AMR and AMU from veterinary practitioners in Pakistan between July 25, 2020, and February 2, 2021. The questionnaire was comprised of four sections: 1) Demographic information of the respondents, 2) Knowledge about AMR, and AMU, 3) Antibiotic prescribing behavior, attitudes and influencing drivers and 4) Practices of respondents about AMU and drug disposal.

RESULTS

A total of 545 participants (Male 84%, Female 16%) completed the survey. The respondents' qualification (P = 0.008), gender (P = 0.007) and type of practitioner (P < 0.001) had a significant association with the mean knowledge score about AMR. Most of the veterinarians had never attended any training, symposium, or awareness session on AMR (63%) and methods to detect antibiotic residues (71%). Participating veterinarians frequently included "critically important antimicrobials" in their treatment regimens. Most veterinarians (60%) prescribed antibiotics for viral diseases. Our study showed that about 44% of veterinarians disposed of expired drugs in the garbage. Antibiotics were prescribed as mass medication and for prophylaxis by 59% and 33% of the veterinarians, respectively, while about 60% of the veterinarians prescribed antibiotics starting with double doses in their treatment regimens. Importantly, only 4% of the veterinarians recognized the concept of One Health. Male veterinarians had higher odds of prescribing mass medication (OR=3.07, P < 0.001) and use of antibiotics for disease prophylaxis (OR=2.31, P = 0.002) than females, whereas improper disposal of expired antimicrobials (OR=2.12, P = 0.003) was more common in female veterinarians. Government veterinarians had 2 (OR=1.95, P = 0.016) and 3 (OR=3.05, P < 0.001) times higher odds to prescribe antibiotics prophylactically and for mass treatments, respectively compared to full-time private veterinarians.

CONCLUSION

Our study identifies key factors influencing veterinarians' decision about antimicrobial prescription and highlights important shortcomings such as lack of training on rational use of antimicrobials, frequent use of antimicrobials for mass medication and prophylaxis, widespread use of critically important antimicrobials, and improper disposal practices. There is a dire need to improve knowledge of veterinary practitioners regarding AMR and to adopt a One Health approach to rationalize AMU at the national level in line with the regional and international guidelines.

Identification of Multiple Variant Extensively Drug-Resistant Typhoid Infections across Pakistan

Typhoid fever, caused by Salmonella enterica serovar Typhi (S. Typhi), is a life-threatening bacterial infection. Recently, an outbreak of a new sublineage of extensively drug resistant (XDR) S. Typhi emerged in Pakistan in the province of Sindh. This sublineage had both a composite multidrug resistance transposon integrated on the chromosome and an acquired IncY plasmid carrying the extended spectrum beta-lactamase, blaCTX-M-15, which conferred resistance to third-generation cephalosporins. We observed previously that XDR typhoid had spread beyond the originating southern Sindh Province. Thus, we sought to determine the genetic diversity of 58 ceftriaxone-resistant S. Typhi clinical isolates by whole genome sequencing collected across Pakistan from November 2018 to December 2020 to provide insights into the molecular epidemiology of the evolving outbreak. We identify multiple novel genomic integrations of the extended spectrum beta-lactamase gene into the chromosome in S. Typhi, revealing the existence of various XDR typhoid variants circulating in the country. Notably, the integration of the IncY plasmid bearing antibiotic resistance genes may allow for subsequent plasmid acquisition by these variants, potentially leading to further plasmid-borne multidrug resistance. Our results can inform containment initiatives, help track associated outcomes and international spread, and help determine how widespread the risk is.

Typhoid Fever in the Eastern Mediterranean Region: A Systematic Review, 1990-2021

The occurrence and antimicrobial resistance (AMR) of typhoid fever in the WHO Eastern Mediterranean Region (EMR) are poorly characterized. Robust surveillance data are needed to inform strategies for typhoid control and prevention in the region. We conducted a systematic review of typhoid fever occurrence, complications, and AMR patterns in EMR countries. We identified 70 studies published from 1990 to 2021, including a total of 44,541 cases with blood culture confirmed typhoid fever in 12 EMR countries, with 48 (69%) studies and 42,008 cases from Pakistan. Among 56 studies with AMR data, fluroquinolone (68% of 13,013 tested isolates), and multidrug resistance (40% of 15,765 tested isolates) were common. Forty (57%) of the 56 studies were from Pakistan, and all reports of extensively drug resistant Salmonella Typhi (48% of 9,578 tested isolates) were from studies in Pakistan. Our findings support the need for continued efforts to strengthen surveillance and laboratory capacity for blood-culture detection of typhoid fever in the region, including data from an ongoing collaboration among CDC, the American University of Beirut, and the WHO EMR office.

Understanding the Mechanism of Antimicrobial Resistance and Pathogenesis of Salmonella enterica Serovar Typhi

Salmonella enterica serovar Typhi (S. Typhi) is a Gram-negative pathogen that causes typhoid fever in humans. Though many serotypes of Salmonella spp. are capable of causing disease in both humans and animals alike, S. Typhi and S. Paratyphi are common in human hosts only. The global burden of typhoid fever is attributable to more than 27 million cases each year and approximately 200,000 deaths worldwide, with many regions such as Africa, South and Southeast Asia being the most affected in the world. The pathogen is able to cause disease in hosts by evading defense systems, adhesion to epithelial cells, and survival in host cells in the presence of several virulence factors, mediated by virulence plasmids and genes clustered in distinct regions known as Salmonella pathogenicity islands (SPIs). These factors, coupled with plasmid-mediated antimicrobial resistance genes, enable the bacterium to become resistant to various broad-spectrum antibiotics used in the treatment of typhoid fever and other infections caused by Salmonella spp. The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains in many countries of the world has raised great concern over the rise of antibiotic resistance in pathogens such as S. Typhi. In order to identify the key virulence factors involved in S. Typhi pathogenesis and infection, this review delves into various mechanisms of virulence, pathogenicity, and antimicrobial resistance to reinforce efficacious disease management.

Outbreak of Typhoid Fever in Children of Urban Vellore: A Report from the Surveillance for Enteric Fever in India Cohort

We report an outbreak of typhoid fever between April and June 2019 in the Surveillance for Enteric Fever in India cohort, a pediatric cohort from four contiguous semi-urban settlements of Vellore in South India. This cohort of children 6 months to 15 years of age was under surveillance from October 2017 to December 2019. A clustering of typhoid cases in the cohort was noted with reference to time, place, and person. The overall typhoid attack rate in the cohort was 0.9%, with the highest attack rate of 1.7% being documented in one of the four areas. The rate of hospitalization and complications in children who were typhoid positive during the outbreak was 28% and 2%, respectively. Given the background of suboptimal water, sanitation, and hygiene, and the risk of typhoid fever outbreaks in these settings, it is imperative that a typhoid vaccine be considered for introduction as a pragmatic preventive approach.

Screening of Rhamnus Purpurea (Edgew.) Leaves for Antimicrobial, Antioxidant, and Cytotoxic Potential

Exploring new antimicrobial and cytotoxic drugs has been one of the most active areas of research. Rhamnus purpurea (Edgew.) buckthorn (Rhamnaceae) is a wild shrub traditionally used in Pakistan for the treatment of various ailments including cancer and infectious diseases. The aim of this study is to find novel antimicrobial and cytotoxic agents of plant origin. The crude methanol extract and full range of fractions of R. purpurea leaves were screened for the said activities using in vitro antimicrobial, antioxidant, and cytotoxic models following standard protocols. The antimicrobial activity was evaluated using the agar well diffusion method, while the antioxidant activity was assessed with 1,1-diphenyl-2-picryl hydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The cytotoxic effect was investigated against the human cancer cell lines i.e. Caco-2 (gut), A549 (lung), HepG2 (liver), and MDA-MB-231 (breast) by MTS assay. In addition, toxicity studies were conducted on renal and alveolar primary epithelial cells (HRPTEpiC and HPAEpiC, respectively). Phytochemical investigation showed the presence of secondary metabolites such as alkaloids, saponins, tannins, glycosides, phenols, carbohydrates, proteins, and flavonoids. The n-hexane and chloroform fractions showed significant activity against Staphylococcus aureus (MIC 0.60 and 0.68 mg/mL, respectively), Salmonella typhi (MIC 0.48 and 0.45 mg/mL, respectively), and Bacillus subtilis (MIC 0.54 and 0.76 mg/mL, respectively). Among fungal strains, crude methanol and chloroform fractions exhibited significant activity against Fusarium solani (MIC 0.53 and 0.44 mg/mL, respectively) and Aspergillus niger (MIC 0.47 and 0.42 mg/mL, respectively). The crude methanol, n-hexane and chloroform fractions revealed the highest antioxidant activity at 1000 μg/mL, compared to that of ascorbic acid. The n-hexane fraction showed a significant cytotoxic effect against Caco-2, A549, and HepG2 cell lines with IC50 values of 5.65 ± 0.88, 5.50 ± 0.90, and 4.95 ± 1.0 μg/mL, respectively. Similarly, the chloroform fraction depicted significant activity against Caco-2, A549, and HepG2 cell lines with IC50 values of 4.55 ± 1.25, 4.65 ± 1.55, and 2.85 ± 0.98 μg/mL, respectively. The crude methanol extract and almost all fractions exhibited the highest selectivity index (>2.0) for Caco-2, A549, and HepG2 cancer cell lines, providing safety data for this study. The results showed that R. purpurea leaves have excellent antimicrobial, antioxidant, and cytotoxic potential and warrant further studies to search for novel compounds for the said activities.

Macrophage Cell Lines and Murine Infection by Salmonella enterica Serovar Typhi L-Form Bacteria

Antibiotic resistance of pathogenic bacteria has emerged as a major threat to public health worldwide. While stable resistance due to the acquisition of genomic mutations or plasmids carrying antibiotic resistance genes is well established, much less is known about the temporary and reversible resistance induced by antibiotic treatment, such as that due to treatment with bacterial cell wall-inhibiting antibiotics such as ampicillin. Typically, ampicillin concentration in the blood and other tissues gradually increases over time after initiation of the treatment. As a result, the bacterial population is exposed to a concentration gradient of ampicillin during the treatment of infectious diseases. This is different from in vitro drug testing, where the organism is exposed to fixed drug concentrations from the beginning until the end. To mimic the mode of antibiotic exposure of microorganisms within host tissues, we cultured the wild-type, ampicillin-sensitive Salmonella enterica serovar Typhi Ty2 strain (S. Typhi Ty2) in the presence of increasing concentrations of ampicillin over a period of 14 days. This resulted in the development of a strain that displayed several features of the so-called L-form of bacteria, including the absence of the cell wall, altered shape, and lower growth rate compared with the parental form. Studies of the pathogenesis of S. Typhi L-form showed efficient infection of the murine and human macrophage cell lines. More importantly, S. Typhi L-form was also able to establish infection in a mouse model to the extent comparable to its parental form. These results suggested that L-form generation following the initiation of treatment with antibiotics could lead to drug escape of S. Typhi and cell to cell (macrophages) spread of the bacteria, which sustain the infection. Oral infection by the L-form bacteria underscores the potential of rapid disease transmission through the fecal-oral route, highlighting the need for new approaches to decrease the reservoir of infection.

role of Lactobacillus casei on some physiological and biochemical parameters in male laboratory rats infection with salmonellosis

This research was conducted to isolation and diagnosis of Salmonella typhimurium that caused child diarrhea infections, whom attend in Salah-Adin Teaching Hospital in Tikrit. and determine the susceptibility of isolates against some antibiotics, also, determine the Lactobacillus casei as probiotics which, isolation and identification from fermented dairy samples collected from different local in Salah-Adin governorate markets, then assay the effect of orally dosage of probiotics on some physiological and biological parameters in rats that infected with Salmonella typhimurium isolate. Salmonella typhimurium were appeared at 15 isolates from child diarrhea infections samples and the Lb. casei isolates from fermented dairy products, then identified according to morphological, microscopic, cultural and biochemical characterizes, then selective the probiotics isolate from Lb. casei which depended according to their ability to grow in pH 2 and able to tolerance growth at 0.3% bile salts, furthermore their ability to adhesion with intestine mucus surface at 43.8%.

Understanding of Future Prescribers About Antimicrobial Resistance and Their Preparedness Towards Antimicrobial Stewardship Activities in Pakistan: Findings and Implications

Background: Insufficient antimicrobial-related training for physicians during their undergraduate education could have a negative impact on their prescribing. Unlike previous studies, this study not only explored the understanding and perception of Pakistani medical students about antibiotics and resistance, but also their preparedness towards antimicrobial stewardship programs. Methods: An online cross-sectional study was undertaken with final-year medical students using a validated questionnaire from January 2021 to May 2021. Descriptive and inference statistics were applied for data analysis. Results: Of 411 students, only 6.3% had undergone antimicrobial resistance (AMR) training. 16.1% of students believed that antibiotics are effective for viral ailments. More than half of the students agreed that AMR is a major healthcare problem in Pakistan (65.9%). Most students viewed poor infection control practices (66.9%), the use of too many broad-spectrum antibiotics (68.4%) for a longer duration (62.8%) with inadequate doses (67.9%) as the causes of AMR. The student's preparation was insufficient in interpreting microbiological and pathological results (26.3%), selecting the correct antibiotics (22.1%), and awareness of the antibiotic spectrum (20.9%). The median preparedness score showed significant differences with sex (p = 0.049), age (p < 0.001), institute type (p = 0.014), and family income (p = 0.006). Conclusion: Pakistani medical students showed adequate understanding of antibiotics, but lacked preparedness for several components of ASPs, including interpretation of microbiological results and spectrum of antibiotics. More steps need to be taken to prepare medical students for AMR and stewardship initiatives adequately.

The Burden of Typhoid Fever in Sub-Saharan Africa: A Perspective

While typhoid fever has largely been eliminated in high-income regions which have developed modern water, sanitation, and hygiene facilities, it remains a significant public health burden resulting in morbidity and mortality among millions of individuals in resource-constrained settings. Prevention and control efforts are needed that integrate several high-impact interventions targeting facilities and infrastructure, including those addressing improvements in sanitation, access to safe water, and planned urbanization, together with parallel efforts directed at effective strategies for use of typhoid conjugate vaccines (TCV). The use of TCVs is a critical tool with the potential of having a rapid impact on typhoid fever disease burden; their introduction will also serve as an important strategy to combat evolving antimicrobial resistance to currently available typhoid fever treatments. Well-designed epidemiological surveillance studies play a critical role in establishing the need for, and monitoring the impact of, typhoid fever control and prevention strategies implemented by public health authorities. Here, we present a perspective based on a narrative review of the impact of typhoid fever on morbidity and mortality in sub-Saharan Africa and discuss ongoing surveillance activities and the role of vaccination in prevention and control efforts.

Antimicrobial resistance among GLASS priority pathogens from Pakistan: 2006-2018

Background

In 2018 Pakistan initiated its national antimicrobial resistance (AMR) surveillance aligned with Global Antimicrobial Surveillance System (GLASS). To complement this surveillance, we conducted a situational analysis of AMR rates among GLASS organisms in the country. Data from published studies and from antibiograms was compared and role of antibiograms as potential contributors to national AMR surveillance explored.

Methods

AMR rates for GLASS specified pathogen/antimicrobials combination from Pakistan were reviewed. Data sources included published studies (2006–2018) providing AMR rates from Pakistan (n = 54) as well as antibiograms (2011–2018) available on the Pakistan Antimicrobial Resistance Network (PARN) website. Resistance rates were categorized as follows: Very low: 0–10%, Low: 11–30%, Moderate: 30–50% and High: > 50%.

Results

Published data from hospital and community/laboratory-based studies report resistance rates of > 50% and 30–50% respectively to 3rd generation cephalosporins, fluoroquinolones and cotrimoxazole amongst Klebsiella pneumoniae and Escherichia coli. Carbapenem resistance rates amongst these organisms remained below 30%. High (> 50%) resistance was reported in Acinetobacter species to aminoglycosides and carbapenems among hospitalized patients. The evolution of ceftriaxone resistant Salmonella Typhi and Shigella species is reported. The data showed > 50% to fluoroquinolones amongst Neisseria gonorrhoeae and the spread of methicillin resistant Staphylococcus aureus (< 30%; 2008) to (> 50%; 2010) in hospital settings. Resistance reported in published studies aligned well with antibiogram data. The latter also captured a clear picture of evolution of resistance over the study period.

Conclusion

Both published studies as well antibiograms suggest high rates of AMR in Pakistan. Antibiogram data demonstrating steady increase in AMR highlight its potential role towards supplementing national AMR surveillance efforts particularly in settings where reach of national surveillance may be limited.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06795-0.

Outbreak of ceftriaxone-resistant Salmonella enterica serotype Typhi-Tiruchirappalli, Tamil Nadu, India, June 2018

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Surveillance detected ceftriaxone-resistant Salmonella enterica serotype Typhi

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Investigation revealed illness associated with eating in a restaurant

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Illness likely due to contaminated food and use of unchlorinated water

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Investigation highlights the value of surveillance in detecting emerging pathogens

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Timely and detailed investigations and strengthening of food safety are required

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.

Azithromycin and cefixime combination versus azithromycin alone for the out-patient treatment of clinically suspected or confirmed uncomplicated typhoid fever in South Asia: a randomised controlled trial protocol

Background: Typhoid and paratyphoid fever (enteric fever) is a common cause of non-specific febrile infection in adults and children presenting to health care facilities in low resource settings such as the South Asia.  A 7-day course of a single oral antimicrobial such as ciprofloxacin, cefixime, or azithromycin is commonly used for its treatment. Increasing antimicrobial resistance threatens the effectiveness of these treatment choices. We hypothesize that combined treatment with azithromycin (active mainly intracellularly) and cefixime (active mainly extracellularly) will be a better option for the treatment of clinically suspected and culture-confirmed typhoid fever in South Asia.

Methods: This is a phase IV, international multi-center, multi-country, comparative participant-and observer-blind, 1:1 randomised clinical trial. Patients with suspected uncomplicated typhoid fever will be randomized to one of the two interventions: Arm A: azithromycin 20mg/kg/day oral dose once daily (maximum 1gm/day) and cefixime 20mg/kg/day oral dose in two divided doses (maximum 400mg bd) for 7 days, Arm B: azithromycin 20mg/kg/day oral dose once daily (max 1gm/day) for 7 days AND cefixime-matched placebo for 7 days. We will recruit 1500 patients across sites in Bangladesh, India, Nepal, and Pakistan. We will assess whether treatment outcomes are better with the combination after one week of treatment and at one- and three-months follow-up.

Discussion: Combined treatment may limit the emergence of resistance if one of the components is active against resistant sub-populations not covered by the other antimicrobial activity. If the combined treatment is better than the single antimicrobial treatment, this will be an important result for patients across South Asia and other typhoid endemic areas.

Clinicaltrials.gov registration: NCT04349826 (16/04/2020)

Azithromycin and cefixime combination versus azithromycin alone for the out-patient treatment of clinically suspected or confirmed uncomplicated typhoid fever in South Asia: a randomised controlled trial protocol

Background: Typhoid and paratyphoid fever (enteric fever) is a common cause of non-specific febrile infection in adults and children presenting to health care facilities in low resource settings such as the South Asia.  A 7-day course of a single oral antimicrobial such as ciprofloxacin, cefixime, or azithromycin is commonly used for its treatment. Increasing antimicrobial resistance threatens the effectiveness of these treatment choices. We hypothesize that combined treatment with azithromycin (active mainly intracellularly) and cefixime (active mainly extracellularly) will be a better option for the treatment of clinically suspected and culture-confirmed typhoid fever in South Asia. Methods: This is a phase IV, international multi-center, multi-country, comparative participant-and observer-blind, 1:1 randomised clinical trial. Patients with suspected uncomplicated typhoid fever will be randomized to one of the two interventions: Arm A: azithromycin 20mg/kg/day oral dose once daily (maximum 1gm/day) and cefixime 20mg/kg/day oral dose in two divided doses (maximum 400mg bd) for 7 days, Arm B: azithromycin 20mg/kg/day oral dose once daily (max 1gm/day) for 7 days AND cefixime-matched placebo for 7 days. We will recruit 1500 patients across sites in Bangladesh, India, Nepal, and Pakistan. We will assess whether treatment outcomes are better with the combination after one week of treatment and at one- and three-months follow-up. Discussion: Combined treatment may limit the emergence of resistance if one of the components is active against resistant sub-populations not covered by the other antimicrobial activity. If the combined treatment is better than the single antimicrobial treatment, this will be an important result for patients across South Asia and other typhoid endemic areas. Clinicaltrials.gov registration: NCT04349826 (16/04/2020).

The impact of human vaccines on bacterial antimicrobial resistance. A review

At present, the dramatic rise in antimicrobial resistance (AMR) among important human bacterial pathogens is reaching a state of global crisis threatening a return to the pre-antibiotic era. AMR, already a significant burden on public health and economies, is anticipated to grow even more severe in the coming decades. Several licensed vaccines, targeting both bacterial (Haemophilus influenzae type b, Streptococcus pneumoniae, Salmonella enterica serovar Typhi) and viral (influenza virus, rotavirus) human pathogens, have already proven their anti-AMR benefits by reducing unwarranted antibiotic consumption and antibiotic-resistant bacterial strains and by promoting herd immunity. A number of new investigational vaccines, with a potential to reduce the spread of multidrug-resistant bacterial pathogens, are also in various stages of clinical development. Nevertheless, vaccines as a tool to combat AMR remain underappreciated and unfortunately underutilized. Global mobilization of public health and industry resources is key to maximizing the use of licensed vaccines, and the development of new prophylactic vaccines could have a profound impact on reducing AMR.

A Case Report of Extensively Drug Resistant Typhoid in Karachi, Pakistan: A Major Health Concern to Curb the Outbreak

The disease burden of extensively drug resistant typhoid in developing countries is a major emerging issue that cannot be ignored. Since its emergence from multidrug strains, the majority of typhoid cases in Karachi, Pakistan, have been extensively drug resistant, mostly infecting younger patients. In the study, the authors analysed one such case in an adolescent male and discussed how, by the implementation of national health policies, the spread of these infectious diseases could be prevented and the overall burden on the healthcare system decreased in areas with already limited resources.

Performance of Immunodiagnostic Tests for Typhoid Fever: A Systematic Review and Meta-Analysis

Typhoid fever, also known as typhoid, is a life-threatening bacterial infection that remains a global health concern. The infection is associated with a significant morbidity and mortality rate, resulting in an urgent need for specific and rapid detection tests to aid prevention and management of the disease. The present review aims to assess the specificity and sensitivity of the available literature on the immunodiagnostics of typhoid fever. A literature search was conducted using three databases (PubMed, ProQuest and Scopus) and manual searches through the references of identified full texts to retrieve relevant literature published between 1 January 2011 and 31 December 2020. Of the 577 studies identified in our search, 12 were included in further analysis. Lipopolysaccharides (LPS) and hemolysin E (HlyE) were the most frequently studied antigens. The specimens examined in these studies included serum and saliva. Using blood culture as the gold standard, anti-LPS IgA gave the highest sensitivity of 96% (95% CI: 93–99) and specificity of 96% (95% CI: 93–99) for distinguishing between typhoid cases and healthy controls, whereas the combination of anti-LPS and anti-flagellin total IgGAM gave the highest sensitivity of 93% (95% CI: 86–99) and specificity of 95% (95% CI: 89–100) for distinguishing typhoid cases and other febrile infections. A comparably high sensitivity of 92% (95% CI: 86–98) and specificity of 89% (95% CI: 78–100) were shown in testing based on detection of the combination of anti-LPS (IgA and IgM) and anti-HlyE IgG as well as a slightly lower sensitivity of 91% (95% CI: 74–100) in the case of anti-50kDa IgA. Anti-50kDa IgM had the lowest sensitivity of 36% (95% CI: 6–65) against both healthy and febrile controls. The development of a rapid diagnostic test targeting antibodies against lipopolysaccharides combined with flagellin appeared to be a suitable approach for the rapid detection test of typhoid fever. Saliva is added benefit for rapid typhoid diagnosis since it is less invasive. As a result, further studies could be done to develop additional approaches for adopting such samples.

A review of clinical profile, complications and antibiotic susceptibility pattern of extensively drug-resistant (XDR) Salmonella Typhi isolates in children in Karachi

Background

Enteric fever is a systemic infection caused by Salmonella enterica serovar Typhi and Salmonella enterica serovar Paratyphi A, B, and C. There is an emergence of Typhoid fever caused by extensively drug-resistant Salmonella Typhi strain called XDR S.Typhi. This strain is resistant to recommended first-line antibiotics and cephalosporins. WHO estimated 5274 cases of XDR S.Typhi in Karachi from November 2016 to December 2019. This study aims to determine clinical course, complications and response to treatment of XDR S.Typhi among the pediatric population coming to Indus Hospital.

Method

We reviewed the records of children who had culture-proven XDR S.Typhi infection at Indus Hospital from July 2017 to December 2018. A pre-designed data abstraction form was used to record information about seasonality, demographic details, clinical features and course, treatment, complications and outcomes of the cases of XDR S.Typhi.

Results

The records of 680 children were reviewed. The median (IQR) age of the patients was 5 (2–8) years. More than half (n = 391, 57.5%) of the patients were males. The outcomes were recorded in 270 (40%) patients. Out of these, 234 (86.7%) children got cured within 14 days, while a delayed response to antibiotics was noted in 32 (11.9%) children. Seventy-six (29%) children recovered on a combination of meropenem and azithromycin, 72 (27%) got cured on azithromycin alone, while 15 (6%) responded to meropenem alone.

Conclusion

Our review indicated that children under 5 years of age were affected more with XDR S.Typhi. Azithromycin alone or in combination with meropenem were effective antibiotics for treating XDR S.Typhi in children.