Typhoidal Salmonellae Research Articles

Antisalmonella Activities of Essential Oil of Psidium guajava Leaves: An In vitro and In vivo Study

Background: Life-threatening typhoidal salmonella infection is becoming more difficult to treat due to rising resistance to commonly used antibiotics. This resistance is aided by the biofilm-forming ability of the bacteria. This study investigated the in vitro and in vivo antisalmonella activities of essential oil of Psidium guajava leaves. Methods: Essential oil was extracted from the leaves of Psidium guajava with solvents. The sensitivity of Salmonella Typhi to the essential oil of Psidium guajava (EOPG) was assessed via the agar well diffusion method. Minimum inhibitory, bactericidal and biofilm-inhibitory concentrations (MIC, MBC and MBIC respectively) were measured using micro-broth dilution and crystal violet assay respectively. The effect of EOPG on the bacterial cell membrane was evaluated by measuring the efflux of potassium ions, inorganic phosphate and pyruvic acid. Bioautography and GC-MS were employed to identify the constituents of the active fraction of the EOPG. Effects of EOPG on the level of bacteremia and bone marrow infection in male Wistar rats were determined by plating caudal blood on salmonella-shigella agar. Selected serum cytokines were measured using ELISA kits. Effect on hepatic DNA was measured by comet assay while histological evaluation of the liver of infected rats was done by Hematoxylin and Eosin staining. Results: Essential oil of Psidium guajava leaves (EOPG) inhibited the growth of S. Typhi with a zone of inhibition of 13±0.2mm compared to 31±0.3mm recorded by ciprofloxacin. Minimum inhibitory, minimum bactericidal and minimum biofilm inhibitory concentrations were 25, >50 and 12.5 mg/mL respectively. Exposure to EOPG caused efflux of potassium ions, inorganic phosphate and pyruvic acid in S. Typhi. Oral administration of 50 mg/mL of EOPG reduced bacterial load in the blood and bone marrow of S. Typhi-infected rats significantly (P<0.05) when compared to untreated animals. Infection-induced reduction of serum IL-1β and rise in serum IFN-γ were ameliorated considerably in treated animals. The hepatic DNA of infected animals were protected from breakage in the group administered 50 mg/mL/day of EOPG compared with untreated, ciprofloxacin-treated as well as those administered 100 mg/mL/day of EOPG. Conclusion: EOPG has both in vitro and in vivo anti-salmonella activities, this could be exploited in developing new drug leads for treatment of typhoid fever

Linking epidemiological and genomic data in cases of enteric fever in England to inform clinical management and public health action.

To explore the feasibility of linking data from enhanced surveillance patient questionnaires from each enteric fever case in England with genome sequencing data, including antimicrobial resistance (AMR) profiles, from the corresponding isolate of typhoidal salmonellae. After linking data we interrogated the merged dataset and assessed the utility of passive surveillance data to match and monitor antimicrobial treatment regimens in enteric fever patients with the AMR profiles of the infectious agent. A high proportion of cases were given antibiotics (n = 1230/1415; 86.9%); half of the cases stated the class of antibiotic they were given (n = 630/1239) and half were prescribed cephalosporins (n = 316/630). Reported treatment with a combination of antibiotics increased with symptom severity. Nearly half of isolates (n = 644/1415; 45.5%) had mutations conferring resistance to ciprofloxacin. Based on genome-derived AMR profiles, typhoidal salmonellae isolates inferred to be susceptible to the recommended first-line antimicrobials were twice as likely to be isolated from individuals residing in the least deprived areas compared with the most deprived (n = 26/169; 15.4% versus n = 32/442; 7.2%). Due to the high proportion of missing data obtained from patient interviews, we recommend a more transparent and systematic approach to recording the antibiotic prescription details by healthcare professionals in primary and secondary care. A more robust approach to data capture at this point in the care pathway would enable us to audit inconsistencies in the prescribing algorithms across England and ensure equitable treatment across all sections of society. Integrating prescribing data with the genome-derived AMR profiles of the causative agent at the individual patient level provides an opportunity to monitor the impact of treatment on clinical outcomes, and to promote best practice in real time.

Typhoidal salmonella disease in Mukuru informal settlement, Nairobi Kenya; carriage, diversity, and antimicrobial resistant genes.

Multiple studies have shown that typhoid fever is endemic in developing countries characterized by poor hygiene. A unique way of Salmonella Typhi (S.Typhi) pathogenicity is establishing a persistent, usually asymptomatic carrier state in some infected individuals who excrete large numbers of bacteria in faeces. This study aimed to determine the isolation rate of S.Typhi from blood and stool samples among cases and asymptomatic individuals in the Mukuru informal settlement and identify antibiotic resistance patterns within the same population. We recruited 1014 outpatient participants presenting with typhoid-like symptoms in selected health centres in Nairobi, Kenya. Bacterial isolation was done on Xylose Lysine Deoxycholate agar (XLD) and Mac Conkey agar (Oxoid), followed by standard biochemical tests. Identification was done using API20E, and S.Typhi was confirmed by serotyping using polyvalent antisera 0-9 and monovalent antisera d. The Kirby-Bauer disc diffusion method was used to test the antimicrobial susceptibility of S.Typhi isolates, while Multi-Drug Resistant (MDR) strains were characterized using conventional PCR. Of 1014 participants, 54 (5%) tested positive for S.Typhi. Thirty-eight (70%) of the S.Typhi isolated were from stool samples, while sixteen (30%) were from blood. Three (0.2%) of the isolates were from asymptomatic carriers. Of the 54 S.Typhi isolates, 20 (37%) were MDR. Resistance to ciprofloxacin and nalidixic acid was 43% and 52%, respectively. Resistance to amoxicillin-clavulanic acid (a beta-lactam inhibitor) was 2%. The BlaTEM-1 gene was present in 19/20 (95%) MDR isolates. MDR S.Typhi is prevalent in Mukuru Informal settlement. The sharp increase in nalidixic acid resistance is an indication of reduced susceptibility to fluoroquinolones, which are currently the recommended drugs for the treatment of typhoid fever. This study highlights the need for effective antimicrobial stewardship and routine surveillance of antimicrobial resistance (AMR) to inform policy on the prevention and control of MDR Typhoid disease.

ANTIMICROBIAL RESISTANCE IN SALMONELLA ENTERICA SEROVAR TYPHI: UNDERSTANDING THE MECHANISMS AND PATHOGENICITY OF INFECTION” A COMPREHENSIVE REVIEW

Typhoid Fever is a contagious disease caused by Salmonella enterica serovar typhi. It is also the cause of bloodstream infections in most of the developing countries. The pathogen can escape from the host’s immune response, a feature linked with the capsular structure of bacteria, which contributes to its virulence and is a crucial factor in the dissemination of infection. Salmonella enterica serovars are classified as typhoidal and nontyphoidal salmonella. In this review, we will discuss the ecumenical occurrence of immune strains of Salmonella enterica. We cover the mechanism of antimicrobial resistance in Salmonella, including plasmid-mediated resistance. Antibiotic resistance can occur through various mechanisms, such as deactivation of antibacterial medications, changes in therapeutic targets, and acquisition of foreign DNA coding for resistance determinants through horizontal gene transfer. Additionally, bacteria can employ different efflux pumps to resist antibiotics. These are some of the common ways in which antibiotic resistance is developed. We will explore the factors contributing to its virulence, such as the improper use of antibiotics, gene transfers, recurrent infections, and reduced host immunity. Proper hygiene practices and accurate treatment are necessary to combat typhoid disease, which can be better understood by studying its pathogenesis and diagnosis. The widal test and Typhidot test are essential for the diagnosis of salmonella. Vaccines are available against typhoid. We can overcome disease development through vaccination by choosing safe delivery methods and control strategies.

Presence of Enteric Fever with Unusual Clinical Scenarios: A Case Series

Salmonella species are associated with bacteraemia, diarrhoea, as well as focal infections. Salmonella Typhi is the most pathogenic species. Salmonella Paratyphi B commonly affects immunocompromised hosts. The present case series showcases six cases of infection caused by typhoidal Salmonellae with unusual clinical scenarios. The first case report explains a case of neonatal meningitis where the causative agent was S. Paratyphi B. A case of lumbar spondylodiscitis is also reported where the aetiology was found to be Salmonella Typhi. Case three reports S. Typhi infection in a patient with Pre-B cell Acute Lymphoblastic Leukemia (ALL). S. Paratyphi B was isolated from a blood culture of a patient on haemodialysis and also from ascitic fluid from a case of Chronic Liver Disease (CLD). S. Typhi was isolated from the pleural fluid of a patient with carcinoma of the prostate.

Search for Natural Remedies for the Treatment of Salmonella Typhi Infections

Typhoid is a major public health threat, particularly in areas lacking access to clean water, proper nutrition, and hygienic practices. The emergence of antibiotic resistance, inaccessibility of vaccines to the global south, and asymptomatic carriers of Salmonella typhi (S. typhi) have made tackling the scourge of typhoid a major challenge. Plant-based antimicrobial compounds have opened a new avenue for effectively managing typhoid by minimizing drug-related side effects and targeting the resistant strains of typhoidal salmonella cost-effectively. This review article contains many such candidates, who can potentially modify the typhoid treatment guidelines like Azadirachta indica, Canarium schweinfurthii-derived scopoletin, and Punic granatum, and those that target the resistant strains of S. typhi, like Amaranthus hybridus, and Quercus infectoria and Phyllanthus emblica. The article will also shed light on the challenges and promises associated with phytocompound extraction and standardization as the researchers navigate the uncharted waters of alternative medicinal sources.

Azithromycin susceptibility testing for salmonella enterica isolates: Comparing disk diffusion results with MIC gradient strips

Background: Enteric fever remains an imperative public health problem in developing countries. After the emergence of cephalosporin resistance in Salmonella enterica subsp. enterica serovar Typhi, azithromycin is increasingly being used for oral treatment of enteric fever. Reports of sporadic azithromycin resistance have been reported across the country, additionally, misuse of azithromycin during the COVID-19 pandemic has concerns regarding emerging azithromycin resistance. This study evaluated the reliability of the disc diffusion method as a screening test for detecting azithromycin resistance by comparing it with the minimum inhibitory concentrations (MIC) gradient strip results, in 231 typhoidal salmonellae. Material and Methods: This prospective study was conducted in the Section of microbiology of the Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore from March 2022 to March 2023. Isolates recovered from blood cultures of patients, suffering from enteric fever were selected. Azithromycin susceptibility testing was performed both by disk diffusion and as well as gradient strips and their results were compared. Results: Among typhoidal salmonellae, a significant portion consisted of extensively drug resistant Salmonella Typhi (61.9%). Only one XDR S. Typhi was found to be resistant to azithromycin both by disk diffusion method and MIC gradient strip method, with a MIC value of 64µg/ml. The study found no discrepancy between the disk diffusion and gradient strip methods. Conclusion: The current study found no discordance between disk diffusion and gradient strip test methods for evaluating azithromycin susceptibility among typhoidal salmonellae. Keywords: Azithromycin, disk diffusion testing, enteric fever, Minimum inhibitory concentration, Salmonella Typhi

Ceftriaxone resistant Salmonella enterica serovar Paratyphi A identified in a case of enteric fever: first case report from Pakistan

BackgroundEnteric fever is an acute systemic infectious disease associated with substantial morbidity and mortality in low- and middle-income countries (LMIC), with a global burden of 14.3 million cases. Cases of enteric fever or paratyphoid fever, caused by Salmonella enterica serovar Paratyphi A (S. Para A) have been found to rise in many endemic and non-endemic countries. Drug resistance is relatively uncommon in S. Para A. Here we report a case of paratyphoid fever caused by ceftriaxone resistant S. Para A from Pakistan.Case presentationA 29-year-old female presented with a history of fever, headache, and shivering. Her blood culture revealed a S. Para A isolate (S7), which was resistant to ceftriaxone, cefixime, ampicillin and ciprofloxacin. She was prescribed oral Azithromycin for 10 days, which resulted in resolution of her symptoms.Two other isolates of S. Para A (S1 and S4), resistant to fluoroquinolone were also selected for comparison. DST and whole genome sequencing was performed for all three isolates. Sequence analysis was performed for identification of drug resistance and phylogeny. Whole Genome Sequencing (WGS) of S7 revealed the presence of plasmids, IncX4 and IncFIB(K). blaCTX-M-15 and qnrS1 genes were found on IncFIB(K). The gyrA S83F mutation conferring fluoroquinolone resistance was also found present. Multi-locus sequence typing (MLST) showed the S7 isolate to belong to ST129. S1 and S4 had the gyrA S83Y and S83F mutations respectively.ConclusionsWe highlight the occurrence of plasmid-mediated ceftriaxone resistant strain of S. Para A. This is of significance as ceftriaxone is commonly used to treat paratyphoid fever and resistance in S. Para A is not known. Continuous epidemiological surveillance is required to monitor the transmission and spread of antimicrobial resistance (AMR) among Typhoidal Salmonellae. This will guide treatment options and preventive measures including the need for vaccination against S. Para A in the region.

The influence of COVID-19 barrier measures on the positivity rate of typhoidal salmonellosis and amoebiasis in the Buea Health District, South West Region of Cameroon.

Typhoidal salmonellosis and amoebiasis are prevalent in the Buea Health District (BHD) and it is evident that hand hygiene can reduce the transmissibility of these diseases. The barrier measures enforced by the government, in the wake of the corona virus disease 2019 (COVID-19) pandemic has led to behavioural changes which may have had an influence on the positivity rate of these diseases. This study seeks to determine the influence of COVID-19 barrier measures and the implementation of COVID-19 vaccination on the positivity rate of typhoidal salmonellosis and amoebiasis in the BHD. A retrospective study, with purposive and random sampling methods were used to select health facilities in BHD, whose laboratory records were reviewed using a data extraction form to obtain health information of patients who tested for typhoidal salmonella and/or Entamoeba histolytica from June 1, 2018 to December 31, 2021. Chi-square test was used to compare the positivity rate in the pre-and-COVID-19 and in the pre-and-vaccination era. The positivity rate of typhoidal salmonellosis and amoebiasis dropped from 57.8% and 2.7% in the pre-COVID-19 era to 34% and 1.8% in the COVID-19 era respectively, which were significant (χ2 = 945.8; P<0.001 and χ2 = 11.8; P = 0.001 respectively). Within the COVID-19 era, the positivity rate of salmonellosis and amoebiasis decreased from 39% and 2.6% before the implementation of COVID-19 vaccination to 27.7% and 0.8% respectively in the COVID-19 vaccination era and these differences were significant (χ2 = 149.1; P<0.001 and χ2 = 33.8; P<0.001 respectively). However, the positivity rate of salmonellosis between the rainy (43.5%) and the dry (42.8%) seasons and amoebiasis between the rainy (2.2%) and the dry (2%) seasons were not significantly different (χ2 = 0.6; P = 0.429 and χ2 = 0.54; P = 0.463 respectively). A significant decline in the positivity rate of typhoidal salmonellosis and amoebiasis was observed after the implementation of COVID-19 barrier measures and vaccination.

Potential of a novel flagellin epitope as a broad-spectrum vaccine candidate against enteric fever.

Relentless emergence of antibiotic resistant Salmonella strains, coupled with the drawbacks associated with currently available vaccines against enteric fever, warrants an urgent need to look for new vaccine candidates. Out of the multiple virulence factors harbored by Salmonella, flagella are regarded as one of the most important targets of innate as well as adaptive immune response. Individual Salmonella serotypes alternate between expression of two different antigenic forms encoded by fliC and fljB genes, respectively thereby employing this as a strategy to escape the host immune response. In the present study, using various immunoinformatic approaches, a flagellin epitope, present in both antigenic forms of typhoidal Salmonellae has been targeted. Following B-cell epitope and B-cell derived T-cell epitope prediction and interaction studies with major histocompatibility complexes using molecular docking, a peptide epitope was selected. Further, it was screened for its presence in majority of typhoidal serovars along with other useful attributes, in silico. Thereafter, safety studies were performed with the synthesized peptide. Subsequently, immunization studies were carried out using S. Typhi as well as S. Paratyphi A induced murine peritonitis model. Active immunization with peptide-BSA conjugate resulted in 75% and 80% mice survival following lethal challenge with S. Typhi and S. Paratyphi A respectively, along with a significant IgG antibody titer, thereby highlighting its immunogenic potential. Reduced bacterial burden in vital organs along with improved histoarchitecture and cytokine levels further substantiated the protective efficacy of the proposed candidate. Passive immunization studies with the candidate verified the protective efficacy of the generated antibodies against lethal challenge of bacteria in mice. Given the endemic nature of enteric fever and the antigenic variability observed in Salmonella serotypes, present study highlights the importance of using a vaccine candidate, which, along with generating a strong immune response, also exhibits a broad coverage against both, S. Typhi as well as S. Paratyphi A strains.

S3097 A Rare Cause of Severe Hepatitis: Non-Typhoidal Salmonella

Introduction: Non-typhoidal salmonella (NTS) are food borne pathogens that often result in self-limited gastroenteritis. Derangements in transaminases, indicative of acute hepatitis are seen in 1% to 26% of enteric fever cases caused by salmonella typhi and paratyphi species. There have been very few case reports of hepatitis in non-typhoidal species. We present a case of a young man with severe gastroenteritis and elevated liver enzymes, found to have non typhoidal salmonella enteritis, hepatitis, and bacteremia. Case Description/Methods: We report a 33-year-old man who presented to our emergency department with 1 week of nonbilious, non-bloody emesis with associated green watery diarrhea. He reported eating at a buffet in Jamaica one week prior, with his family having similar, yet milder symptoms. On physical exam he was noted to have scleral icterus and diffuse abdominal tenderness. CT of the abdomen and pelvis was unremarkable. Viral hepatitis serology was negative for hepatitis A IgM, Hepatitis B immune, Hepatitis C negative, Hepatitis E IgM and IgG negative. Trends of the patient’s liver panel can be seen below (Table 1). Serum markers of autoimmune hepatitis were negative. EGD and colonoscopy were performed on day 4 due to persistent symptoms which showed gastritis as well as inflammation throughout the colon. Stool PCR resulted positive for Salmonella enterica on day 4 of hospitalization despite two negative stool cultures. He was started on Ceftriaxone as blood cultures revealed pan-sensitive group D salmonella bacteremia. He was discharged home to complete a 14 day course of antibiotics with levofloxacin 500 mg daily given symptomatic and laboratory improvement (Figure 1). Discussion: Salmonella hepatitis is a rare, yet well documented complication of typhoid salmonella and is hypothesized to occur due to direct invasion of the organism or endotoxin mediated immune liver injury. Salmonella hepatitis can often mimic viral hepatitis. An admission ALT/LDH ratio is a good discriminator between both entities. A ratio greater than 9 can demonstrate viral hepatitis, while less than 9 can be seen in typhoid hepatitis. Our presented patient is unique in that he demonstrated salmonella hepatitis with the non-typhoid serotype. We conclude that non-typhoid salmonella may have the same capacity for hepatic injury as does typhoid salmonella likely through a similar mechanism and should be suspected as the cause of hepatitis when other sources are ruled out in patients infected with salmonella enterica.Figure 1.: Scattered moderate inflammation characterized by altered vascularity, congestion (edema), erythema, friability, loss of vascularity and serpentine ulcerations was found in the transverse colon (1, 2), splenic flexure (3), descending colon (4, 5), sigmoid colon (6), and rectum (7). Table 1. - Liver Panel Day 1 Day 4 Day 7 Day 16 AST (unit/L) 253 258 712 155 ALT (unit/L) 276 454 1,593 569 ALP (unit/L) 74 68 130 109 Total Bilirubin (mg/dL) 1.2 1.0 1.5 0.4 Direct Bilirubin (mg/dL) 0.7 0.6 - - AST = Aspartate transaminase, ALT = Alanine Aminotransferase, ALP = Alkaline phosphatase

Extensively Drug-Resistant Typhoid Outbreak in Pakistan, Experience at a Tertiary Care Hospital in Lahore; A Tip of An Iceberg

Objective: To provide a laboratory-based surveillance report of typhoid fever cases diagnosed at a tertiary care hospital in Lahore during the ongoing outbreak.&#x0D; Study Design: Cross-sectional study.&#x0D; Place and Duration of Study: Department of Microbiology, Combined Military Hospital, Lahore Pakistan, from Mar 2018 to Jun 2019.&#x0D; Methodology: All positive blood culture samples that yielded the growth of Salmonella Typhi were included in the study. The samples were dealt with according to standard microbiological procedures. Antimicrobial susceptibility was performed using Clinical and Laboratory Standards Institute (CLSI) guidelines.&#x0D; Results: During the study period, (377) Typhoidal Salmonellae were isolated, of which 327 (86.7%) were Salmonella Typhi and 50 (13.3%) were Paratyphi A. The percentage of XDR Salmonella isolates was 41.9%.&#x0D; Conclusion: Extensively drug-resistant typhoid fever cases reported in this study represent just the tip of an iceberg. Therefore, nationwide surveillance efforts must be undertaken along with implementing effective preventive measures.

Extensively Drug-Resistant Typhoidal Salmonellae: Are These Bugs Swarming Into Suburban and Rural Areas of Pakistan?

BackgroundTyphoid is a serious public health concern with increasing antibiotic resistance. Early suspicion and choice of susceptible antibiotics are key to avoiding the morbidity and mortality associated with this disease. We have carried out this study to assess the antibiotic sensitivity of typhoidal salmonellae in Kharian, Pakistan.Materials and methodsThis cross-sectional study was carried out at Combined Military Hospital, Kharian, Pakistan, from January 2019 to September 2020. Blood culture specimens from patients clinically suspected of enteric fever were tested through the BacT/ALERT 3D automated blood culture system. Positive microbial growth was further identified by colony morphology, appropriate staining, biochemical testing, and Salmonella-specific grouping sera. Salmonella typhi and Salmonella paratyphi A-C were further analyzed for antimicrobial susceptibility using agar disc diffusion testing by the modified Kirby-Bauer technique. The Clinical and Laboratory Standards Institute (CLSI) guidelines (2018-2020) document M-100 was followed for antibiotic selection and assigning the sensitivity status of the isolates. Meropenem and azithromycin were additionally tested keeping in view the possibility of encountering isolates with extensive antimicrobial resistance.ResultsA total of 315 blood culture samples were received during the study period. Of these, 239 (75.9%) reported negative and 76 (24.1%) were positive. The mean age was 22.37 ± 12.39 years. There were 41 (53.9%) males and 35 (46.1%) females. Salmonella enterica (combined Salmonella typhi and Salmonella paratyphi A) was 100% sensitive to azithromycin, meropenem, and imipenem. Ampicillin and chloramphenicol have 28.9% sensitivity each. Ceftriaxone, co-trimoxazole, and ciprofloxacin revealed 64.5%, 23.7%, and 11.8% sensitivity, respectively. Among them, 11.84% of the isolates were pan-sensitive, 35.5% of the cultures were multidrug-resistant (MDR), and 35.5% of the cultures were extensively drug-resistant (XDR).ConclusionThe study demonstrates that polyresistant typhoidal salmonellae are no more confined to a couple of outbreaks in large cities of Pakistan. It is the tip of the iceberg, and the balance has tilted toward difficult-to-treat typhoid and paratyphoid fevers all across the country owing to significant resistance to the commonly used antityphoid antibiotics (cephalosporins and fluoroquinolones). Azithromycin and carbapenems are offering the last line of defense against the rampant Salmonella typhi and Salmonella paratyphi.

Estimating typhoid incidence from community-based serosurveys: a multicohort study

SummaryBackgroundThe incidence of enteric fever, an invasive bacterial infection caused by typhoidal Salmonellae (Salmonella enterica serovars Typhi and Paratyphi), is largely unknown in regions without blood culture surveillance. The aim of this study was to evaluate whether new diagnostic serological markers for typhoidal Salmonella can reliably estimate population-level incidence.MethodsWe collected longitudinal blood samples from patients with blood culture-confirmed enteric fever enrolled from surveillance studies in Bangladesh, Nepal, Pakistan, and Ghana between 2016 and 2021 and conducted cross-sectional serosurveys in the catchment areas of each surveillance site. We used ELISAs to measure quantitative IgA and IgG antibody responses to hemolysin E and S Typhi lipopolysaccharide. We used Bayesian hierarchical models to fit two-phase power-function decay models to the longitudinal antibody responses among enteric fever cases and used the joint distributions of the peak antibody titres and decay rate to estimate population-level incidence rates from cross-sectional serosurveys.FindingsThe longitudinal antibody kinetics for all antigen-isotypes were similar across countries and did not vary by clinical severity. The seroincidence of typhoidal Salmonella infection among children younger than 5 years ranged between 58·5 per 100 person-years (95% CI 42·1–81·4) in Dhaka, Bangladesh, to 6·6 per 100 person-years (4·3–9·9) in Kavrepalanchok, Nepal, and followed the same rank order as clinical incidence estimates.InterpretationThe approach described here has the potential to expand the geographical scope of typhoidal Salmonella surveillance and generate incidence estimates that are comparable across geographical regions and time.FundingBill & Melinda Gates Foundation.TranslationsFor the Nepali, Bengali and Urdu translations of the abstract see Supplementary Materials section.

Intracellular Salmonella Paratyphi A is motile and differs in the expression of flagella-chemotaxis, SPI-1 and carbon utilization pathways in comparison to intracellular S. Typhimurium.

Although Salmonella Typhimurium (STM) and Salmonella Paratyphi A (SPA) belong to the same phylogenetic species, share large portions of their genome and express many common virulence factors, they differ vastly in their host specificity, the immune response they elicit, and the clinical manifestations they cause. In this work, we compared their intracellular transcriptomic architecture and cellular phenotypes during human epithelial cell infection. While transcription induction of many metal transport systems, purines, biotin, PhoPQ and SPI-2 regulons was similar in both intracellular SPA and STM, we identified 234 differentially expressed genes that showed distinct expression patterns in intracellular SPA vs. STM. Surprisingly, clear expression differences were found in SPI-1, motility and chemotaxis, and carbon (mainly citrate, galactonate and ethanolamine) utilization pathways, indicating that these pathways are regulated differently during their intracellular phase. Concurring, on the cellular level, we show that while the majority of STM are non-motile and reside within Salmonella-Containing Vacuoles (SCV), a significant proportion of intracellular SPA cells are motile and compartmentalized in the cytosol. Moreover, we found that the elevated expression of SPI-1 and motility genes by intracellular SPA results in increased invasiveness of SPA, following exit from host cells. These findings demonstrate unexpected flagellum-dependent intracellular motility of a typhoidal Salmonella serovar and intriguing differences in intracellular localization between typhoidal and non-typhoidal salmonellae. We propose that these differences facilitate new cycles of host cell infection by SPA and may contribute to the ability of SPA to disseminate beyond the intestinal lamina propria of the human host during enteric fever.

Abstract 32: Acute suppurative thyroiditis in HIV – Non typhoidal salmonella: Case report and review of the literature

Background: Acute suppurative thyroiditis is a rare disease of thyroid gland. Incidence is less than 1% in immunocompromised hosts. Most common pathogens isolated are Gram positive aerobic cocci. Infections with Gram negative facultative aerobes such as Salmonella are rare.Case Presentation: A 39-year-old retropositive female presented with rapid enlargement of swelling in front of neck, fever and weight loss x 2 weeks. Examination revealed symmetric diffuse swelling that moved with degglutition with overlying erythema and tenderness. Relevent investigations done and CT neck revealed thyroid abscess, covid -19 RAT positive status, microcytic hypochromic anemia. A needle aspiration for symptomatic and diagnostic purposes was performed. Cultures grew Nontyphoidal salmonella. She was treated with 4-week course of oral antibiotics.Conclusion: A thyroid abscess is rare, potentially life threatening disease. However, a high index of suspicion is required to make diagnosis and differentiate from subacute thyroiditis a relatively benign condition. Management is directed at minimizing morbidity. The mainstay treatment is medical, but surgery is sometimes necessary to achieve adequate source control, particularly when complications arise.Keywords: Acute suppurative thyroiditis, COVID 19 infection, retrovirus, Salmonella sp., thyroid abscess

Non Typhoidal Salmonellae and its aetiological spectrum-An overview with Indian perspective

Non Typhoidal Salmonellae (NTS) is emerging as a major health problem. NTS serovars have a wide variety of host range varying from domestic animals, aquatic fauna, reptiles, arthropods, leafy vegetables and many more. This zoonotic infection manifests as self limited gastroenteritis associated with food poisoning to fatal extra intestinal invasive infections. In this overview, an attempt is made to compile the documented reports due to NTS from Indian subcontinent for the last 5 decades, searching the available databases. These reports emphasizes the role of NTS in diverse clinical infections and the possible links of transmission. Prophylactic measures such as adoption of quality measures in fish and meat processing units, vaccination of farm animals, serotyping of all NTS strains, above all health education and public awareness program should be made mandatory to minimize the incidence of NTS in our country.

Analysis of Blood Culture Data Influences Future Epidemiology of Bloodstream Infections: A 5-year Retrospective Study at a Tertiary Care Hospital in India

ABSTRACTBackgroundBlood cultures are the most significant samples received in a microbiology laboratory. Good quality control of pre-analytic, analytic, and post-analytic stages can have a significant impact on patient outcomes. Here, we present the improvements brought about by reviewing blood culture data with clinicians at a tertiary care institute in India.MethodsFour-year blood culture data (phase I—February 2014–February 2018) were shared with clinicians in the clinical grand round. Several take-home messages were discussed in a quiz format, and a number of holistic quality control measures were implemented at different levels. Based on observable changes in blood culture reports, another dataset was analyzed and compared in phase II (April 2018–April 2019).ResultsIn phase II, the blood culture contamination rate improved from 6 to 2% along with four times reduction in ICU isolates and three times increased isolation of salmonellae and pneumococci. The development of resistance in Klebsiella pneumoniae to carbapenems and piperacillin–tazobactam was reduced. Colistin resistance in ICU isolates hovered around 15%. Vaccine-preventable pneumococcal serotypes were predominant in the under-five age-group. Typhoidal salmonellae were more commonly isolated from adults with 50% showing sensitivity to pefloxacin and 97% to ampicillin, chloramphenicol, and cotrimoxazole. Candida parapsilosis was the leading non-albicans Candida (NAC). Fluconazole resistance was observed in 50% of NAC.ConclusionReviewing blood culture data with clinicians mutually helped us to improve the overall quality of blood culture reports. It had a major impact on epidemiological trends and thus, found to be superior to just sharing an antibiogram with the clinicians.How to cite this articleSharma A, Samaddar A, Maurya A, Hada V, Narula H, Shrimali T, et al. Analysis of Blood Culture Data Influences Future Epidemiology of Bloodstream Infections: A 5-year Retrospective Study at a Tertiary Care Hospital in India. Indian J Crit Care Med 2021;25(11):1258–1262.

In Vitro Susceptibility of Typhoidal, Nontyphoidal, and Extended-Spectrum-β-Lactamase-Producing Salmonella to Ceftolozane/Tazobactam.

Both typhoidal and nontyphoidal salmonellae are included in the top 15 drug-resistant threats described by the U.S. Centers for Disease Control and Prevention. There is an urgent need to look for alternative antibiotics for the treatment of Salmonella infections. We used the broth microdilution test to examine the in vitro susceptibilities of typhoidal and nontyphoidal salmonellae, including isolates positive for extended-spectrum β-lactamase (ESBL), to ceftolozane/tazobactam and six other antibiotics. Of the 313 (52 typhoidal and 261 nontyphoidal) Salmonella isolates tested, 98.7% were susceptible to ceftolozane/tazobactam. Based on the overall MIC50/90 values, Salmonella isolates were more susceptible to ceftolozane/tazobactam (0.25/0.5 mg/L) than all the comparator agents: ampicillin (≥64/≥64 mg/L), levofloxacin (0.25/1 mg/L), azithromycin (4/16 mg/L), ceftriaxone (≤0.25/4 mg/L), chloramphenicol (8/≥64 mg/L), and trimethoprim/sulfamethoxazole (1/≥8 mg/L). Comparison of the activities of the antimicrobial agents against nontyphoidal Salmonella isolates according to their serogroups showed that ceftolozane/tazobactam had the highest activity (100%) against Salmonella serogroup D, G, I, and Q isolates, whereas the lowest activity (85.7%) was observed against serogroup E isolates. All 10 ESBL-producing Salmonella isolates (all nontyphoidal), of which 8 were CTX-M-55 producers and 2 were CTX-M-65 producers, were sensitive to ceftolozane/tazobactam, albeit with MIC50/90 values higher (1/2 mg/L) than those for non-ESBL producers (0.25/0.5 mg/L). In summary, our data indicate that ceftolozane/tazobactam is active against most strains of both typhoidal and nontyphoidal salmonellae and also against ESBL-producing salmonellae.

In vitro and in vivo Activities of Psidium guajava and Azadirachta indica Leaf Extracts and solvent Fractions against Salmonella Typhi

Typhoidal salmonella infections remain a challenge in the health care system in sub-Saharan Africa. Carrier status and advent of multi-drug resistant S. Typhi strains have necessitated the search for new drug leads. Hence, this study aims at investigating P. guajava and A. indica leaves for anti-salmonella activities. Guava and neem leaves were extracted by maceration in methanol and fractionated by solvent partitioning. In vitro activities were assessed by agar well diffusion and broth micro-dilution methods. Sixty male rats were randomized to 10 groups of 6 animals each for the in vivo experiments. Groups of rats except, normal control, were induced with 0.5McFarland of S. Typhi suspension orally. Treatment groups received 200 mg/kg body weight of extracts and fractions, and the control groups were treated with 14.29mg/kg body weight of ciprofloxacin and 1%v/v DMSO for 7 days post-infection. Biochemical parameters were determined spectrophotometrically. Hematological parameters were analyzed with automated hematology diagnostic machine. All fractions of P. guajava and three of A. indica inhibited S. Typhi growth with Zone of Inhibition (ZI) ranging from 11-15 mm. Active fractions inhibited 48.60-62.45% of S. Typhi biofilm formation at 25 mg/mL with Minimum Bactericidal Inhibitory Concentration (MBIC) of 0.39-12.5 mg/mL. All fractions improved body weight of treated rats and inhibited bacteremia at 44.75 and 95.94%. Hematological parameters improved in all fractions-treated rats. MDA was not significantly (p&lt;0.05) altered in all groups. One fraction of P. guajava (ePg) lowered the elevated level in concentration of Nitric oxide (NO) while all fractions enhanced the lowered activity of SOD. Elevated (lactate dehydrogenase (LDH), aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and bilirubin (BIL) were lowered by all fractions to various extents in treated rats. Fractions of P. guajava, and A. indica could be further considered for identification of active anti-salmonella principle(s).