Typhoid Fever

Salmonella infection among the pediatric population at a tertiary care children's hospital in central Nepal: a retrospective study

Background

Typhoid fever, an infective bacterial disease, is capable of causing fatal systemic infection in humans, and in an era of antimicrobial resistance, it has become of public health importance. This study aimed to investigate the laboratory diagnosis of Salmonella bloodstream infection, its serotype, antimicrobial resistance pattern, and seasonal variation at a tertiary care children's hospital.

Methods

We undertook a retrospective, cross-sectional study by reviewing hospital-based laboratory records of patients whose blood culture samples were submitted from the outpatient department to the laboratory of a tertiary care children's hospital in Kathmandu, Nepal, from January 2017 to January 2019.

Results

Among the total blood culture samples obtained (n = 39,771), bacterial isolates (n = 1,055, 2.65%) belonged either to the Genus Enterobacteriaceae or Genus Acinetobacter. Altogether (n = 91, 8.63%), isolates were positive for Salmonella spp., which were further identified as Salmonella enterica subsp. enterica ser. Typhi (n = 79, 7.49%), Salmonella enterica subsp. enterica ser. Paratyphi A (n = 11, 1.04%), and Salmonella enterica subsp. enterica ser. Paratyphi B (n = 1, 0.1%). The median age of patients was 6  years (IQR: 4-9), with male and female patients constituting (n = 53, 58.24%; OR, 1.0; 95% CI, 0.60-1.67) and (n = 38, 41.76%; OR, 0.98; 95% CI, 0.49-2.05) cases, respectively. The disease was observed throughout the year, with a high prevalence toward the spring season (March-May). An antibiogram showed resistance more toward nalidixic acid with S. Typhi, comprising half the isolates (n = 52, 65.82%; p = 0.11). Resistance toward β-lactams with β-lactamase inhibitors (amoxicillin/clavulanate; 1.27%) was seen in a single isolate of S. Typhi. The multidrug resistance pattern was not pronounced. The multiple antibiotic resistance (MAR) index was in the range between 0.14 and 0.22 in S. Typhi and 0.22 and 0.23 in S. Paratyphi.

Conclusion

Salmonella Typhi was the predominant ser. Infection was common among children between 1 and 5 years of age, showing male predominance and with the spring season contributing to a fairly higher number of cases. Antimicrobial susceptibility testing of S. Typhi showed more resistance toward nalidixic acid, with only a single isolate resistant to β-lactamase inhibitors (amoxicillin/clavulanate). Alarming multidrug resistance patterns were not observed. The MAR index in this study indicates the importance of the judicious use of antimicrobials and hospital infection prevention and control practices.

The Prolonged Treatment of Salmonella enterica Strains with Human Serum Effects in Phenotype Related to Virulence

Salmonella enterica as common pathogens of humans and animals are good model organisms to conduct research on bacterial biology. Because these bacteria can multiply in both the external environments and in the living hosts, they prove their wide adaptability. It has been previously demonstrated that prolonged exposition of Salmonella serotype O48 cells to normal human serum led to an increase in resistance to sera in connection with the synthesis of very long O-antigen. In this work, we have studied the phenotype connected to virulence of Salmonella enterica strains that were subjected to consecutive passages in 50% human serum from platelet-poor plasma (SPPP). We found that eight passages in SPPP may not be enough for the bacteria to become serum-resistant (S. Typhimurium ATCC 14028, S. Senftenberg). Moreover, C1q and C3c complement components bound to Salmonellae (S. Typhimurium ATCC 14028, S. Hammonia) membrane proteins, which composition has been changed after passaging in sera. Interestingly, passages in SPPP generated genetic changes within gene fljB, which translated to cells’ motility (S. Typhimurium ATCC 14028, S. Erlangen). One strain, S. Hammonia exposed to a serum developed a multi-drug resistance (MDR) phenotype and two S. Isaszeg and S. Erlangen tolerance to disinfectants containing quaternary ammonium salts (QAS). Furthermore, colonial morphotypes of the serum adaptants were similar to those produced by starter cultures. These observations suggest that overcoming stressful conditions is manifested on many levels. Despite great phenotypic diversity occurring after prolonged exposition to SPPP, morphotypes of colonies remained unchanged in basic media. This work is an example in which stable morphotypes distinguished by altered virulence can be confusing during laboratory work with life-threatening strains.

Coinfection of enteric fever and hepatitis A

Poor sanitation and contaminated food and water are major risk factors for several infectious diseases like enteric fever and hepatitis A, but their coinfection is uncommon. Although the liver is frequently affected in typhoid fever, substantial hepatic dysfunction in an appropriately treated patient is uncommon. Our patient had high-grade fever with mild transaminitis and blood culture that grew Salmonella typhi Despite being treated with culture-sensitive antibiotic at adequate dosage, he developed jaundice and had worsening transaminitis (>1000 IU/L) which was suggestive of hepatotropic virus infection. Hepatitis A IgM was positive. He was treated appropriately with which clinical and laboratory parameters resolved.

Ovarian abscess caused by Salmonella enterica serovar Typhi: a case report

Background

Typhoid fever is a human-specific disease caused by a bacterium, Salmonella enterica subspecies enterica serovar Typhi. It is transmitted through ingestion of contaminated food or water. It is mostly diagnosed by blood culture. Salmonella Typhi usually manifests as a febrile illness with bacteremia after initial entry through the gastrointestinal route, but it can occasionally cause significant disease in extraintestinal sites. We report a case of a girl in Fiji with a right ovarian abscess infected by Salmonella Typhi.

Case presentation

A 14-year-old iTaukei (indigenous Fijian) girl presented to our hospital with abdominal pain of 1 month’s duration. Two days prior to her admission, she developed high-grade fever and nausea and had one episode of vomiting. On presentation, she appeared unwell; she was tachycardic (116 beats per minute) and febrile (38.8 °C). Her abdominal examination revealed generalized tenderness. Other examination findings were normal. The provisional diagnosis of abdominal sepsis led to an emergency laparotomy during which an enlarged right ovary was found to be spontaneously discharging pus. The ovary was incised and drained, and the patient was commenced on intravenous ceftriaxone 1 g twice daily, cloxacillin 1 g four times daily, and metronidazole 500 mg three times daily. She recovered promptly and was discharged to home on the sixth postoperative day. The purulent material from the ovary grew Salmonella Typhi.

Conclusion

Extraintestinal infections caused by Salmonella Typhi are rare but can cause severe and life-threatening disease. Our patient had a prolonged history of abdominal pain and was found to have a ruptured right ovarian abscess due to Salmonella Typhi. Ovarian abscesses in girls who are not sexually active are not associated with pelvic inflammatory disease and suggest local or hematogenous spread. This case report may increase health workers awareness to include common and endemic infections in the differential diagnosis of unusual clinical presentations to help the initiation of appropriate investigation and management as quickly as possible.

Invasive Salmonellosis in Humans

Human salmonellosis is generally associated with Salmonella enterica from subspecies enterica (subspecies I). Acute infections can present in one of four ways: enteric fever, gastroenteritis, bacteremia, or extraintestinal focal infection. As with other infectious diseases, the course and outcome of the infection depend on a variety of factors, including the infecting organism, the inoculating dose, and the immune status and genetic background of the host. For serovarsTyphi and Paratyphi A there is a clear association between the genetic background of the serovar and systemic infection in humans. For serovars Paratyphi B and Paratyphi C, a good clinical description of the host and detailed population genetics of the pathogen are necessary before more detailed genetic studies of novel virulence factors,or host factors,can be initiated. For the nontyphoidalserovars (NTS) the situation is less clear. Serovars Typhimurium and Enteritidis are the most common within the food chain, and so the large number of invasive infections associated with these serovars is most likely due to exposure rather than to increased virulence of the pathogen. In Africa, however, a closely related group of strains of serovar Typhimurium, associated with HIV infection, may have become host adapted tohumans, suggesting that not all isolates called "Typhimurium" should be considered as a single group. Here we review current knowledge of the salmonellae for which invasive disease in humans is an important aspect of their population biology.

Clinical and microbiological profile of a retrospective cohort of enteric fever in 2 Spanish tertiary hospitals

Enteric fever in high-income countries is diagnosed mainly in patients returning from endemic countries. We assess the clinical, microbiological, and prognosis aspects of enteric fever in 2 Spanish tertiary hospitals. A retrospective observational study was conducted at Vall d'Hebron University Hospital and Ramón y Cajal University Hospital in Spain. We reviewed medical records of all patients who were diagnosed with enteric fever from January 2000 to January 2014 at these hospitals. We identified 47 patients with enteric fever episodes. According to their travel history, 35 (74.5%) patients had travelled to highly endemic countries. Imported enteric fever was acquired mainly in Asia (70.3%). Imported infections were implicated in travelers (48.6%), visiting friends and relatives (40%) and immigrants (11.4%). We found that 12 patients were diagnosed with enteric fever without a travel history (autochthonous infection). The resistance profile of the isolates showed decreased ciprofloxacin susceptibility in 66.7% of the imported group and 8.3% of the autochthonous group (P = 0.001). Salmonella strains from patients returning from Asia had an increased risk of having decreased ciprofloxacin susceptibility (odds ratio, 52.25; 95% confidence interval: 8.6-317.7). Patients with imported enteric fever are at higher risk for having a Salmonella strain with decreased ciprofloxacin susceptibility, especially in patients returning from Asia. Initial treatment with third-generation cephalosporin or azithromycin is strongly recommended until a drug-susceptibility test is available. Prevention strategies such as pretravel counseling and immunization before travel may be beneficial.

Salmonella subtypes with increased MICs for azithromycin in travelers returned to The Netherlands

Antimicrobial susceptibility was analyzed for 354 typhoidal Salmonella isolates collected during 1999-2012 in the Netherlands. In 16.1% of all isolates and in 23.8% of all isolates that showed increased MICs for ciprofloxacin, the MIC for azithromycin was increased. This resistance may complicate empirical treatment of enteric fever.

Survival of Salmonella Typhi and Shigella dysenteriae in dehydrated infant formula

Powdered infant formula has previously been linked to the transmission of various bacterial pathogens in infants resulting in life-threatening disease and death. Survival studies of 2 common foodborne pathogens, Salmonella enterica serovar Typhi and Shigella dysenteriae, in powdered infant formula have not been previously studied despite the potentially devastating consequences from ingestion of these organisms, particularly by newborns, in case of a natural or deliberate contamination event. Therefore, to better predict the risk of S. Typhi and S. dysenteriae infection from consumption of infant formula, the present study was undertaken to determine survival of these microorganisms in dry infant formula under varying atmospheric conditions. A 2-strain cocktail of S. Typhi and a 3-strain cocktail of S. dysenteriae were stored for up to 12 wk in dehydrated infant formula in an ambient air or nitrogen atmosphere. Viable counts of S. Typhi at 12 wk in infant formula revealed a 2.9- and 1.69-log decrease in ambient air and nitrogen atmosphere, respectively. Viable counts of S. dysenteriae at 12 wk in infant formula revealed a 0.81- and 0.42-log decrease in ambient air and nitrogen atmosphere, respectively. These results show that S. Typhi and S. dysenteriae can remain viable for prolonged periods of time in powdered infant formula, and the presence of nitrogen enhances survival.

PRACTICAL APPLICATION

Our goal in this work was to study the survival of S. Typhi and S. dysenteriae in dehydrated storage conditions in infant formula. This interest is partially generated by the possibility of using these 2 microorganisms to deliberately contaminate the food supply. The outcome of this study will help us to have a better idea how to respond and react to the risk of deliberate food contamination.

Combined rapid (TUBEX) test for typhoid-paratyphoid A fever based on strong anti-O12 response: design and critical assessment of sensitivity

Rapid diagnostics can be accurate but, often, those based on antibody detection for infectious diseases are unwittingly underrated for various reasons. Herein, we described the development of a combined rapid test for two clinically-indistinguishable bacterial diseases, typhoid and paratyphoid A fever, the latter fast emerging as a global threat. By using monoclonal antibodies (mAbs) to bacterial antigens of known chemical structures as probes, we were able to dissect the antibody response in patients at the level of monosaccharides. Thus, a mAb specific for a common lipopolysaccharide antigen (O12) found in both the causative organisms was employed to semi-quantify the amounts of anti-O12 antibodies present in both types of patients in an epitope-inhibition particle-based (TUBEX) immunoassay. This colorimetric assay detected not only anti-O12 antibodies that were abundantly produced, but also, by steric hindrance, antibodies to an adjoining epitope (O9 or O2 in the typhoid or paratyphoid bacillus, respectively). Sensitivity and, particularly, reaction intensities, were significantly better than those obtained using an anti-O9 or anti-O2 mAb-probe in the examination of paired sera from 22 culture-confirmed typhoid patients (sensitivity, 81.8% vs 75.0%) or single sera from 36 culture-confirmed paratyphoid patients (52.8% vs 28.6), respectively. Importantly, sensitivity was better (97.1% for typhoid, 75.0% for paratyphoid) if allowance was made for the absence of relevant antibodies in certain specimens as determined by an independent, objective assay (ELISA) — such specimens might have been storage-denatured (especially the older paratyphoid samples) or procured from non-responders. Benchmarking against ELISA, which revealed high concordance between the two tests, was useful and more appropriate than comparing with culture methods as traditionally done, since antibody tests and culture target slightly different stages of these diseases. Paired sera analysis was insightful, revealing 64% of typhoid patients who had no change in antibody titer over 4–16 days, and 14% with no IgM-IgG class-switching.

Differential afferent sensitivity to mucosal lipopolysaccharide from Salmonella typhimurium and Escherichia coli in the rat jejunum

Postinfectious irritable bowel syndrome may develop subsequent to acute bacterial enteritis. We therefore hypothesized that intestinal afferents may develop hypersensitivity upon exposure to luminal lipopolysaccharide (LPS) from pathogens but not from commensal bacteria and that this may be prostaglandin mediated. Extracellular recordings of jejunal afferents were obtained in vivo from male Wistar rats (n = 5 per group; 300-400 g). Lipopolysaccharide from Escherichia coli (E-LPS), Salmonella typhimurium (S-LPS) or vehicle were infused into the intestinal lumen at 5 mg mL(-1). The selective 5-HT(3)-receptor agonist 2-methyl-5-HT (2m5-HT, 15 microgkg(-1), i.v.) was administered at 15-min intervals before and up to 2 h after S-LPS administration. Intraluminal E-LPS had no effect on mesenteric afferent nerve discharge at baseline. By contrast, afferent discharge increased from 21.7 +/- 0.3 impsec(-1) to 28.8 +/- 3.4 impsec(-1) 40 min after S-LPS administration (mean +/- SEM; P < 0.05) and reached 38.8 +/- 4.1 impsec(-1) after 2 h (P < 0.05). The afferent response to 2m5-HT was enhanced 30 min following S-LPS by 30.9 +/- 3.9% (P < 0.05) and remained elevated thereafter. The increase in baseline discharge and sensitivity to 2m5-HT following S-LPS was prevented by pretreatment with naproxen (COX inhibitor, 10 mgkg(-1) i.v.) or AH-6809 (EP1/EP2 receptor antagonist, 1 mg kg(-1)). Intestinal afferents do not alter their discharge rate to LPS from E. coli but to LPS from the pathogenic bacterium S. typhimurium. The latter response entails afferent sensitisation to 2m5-HT that depends on prostanoid release. This acute sensitisation may prime the intestinal afferent innervation for a later development of persistent hypersensitivity.

Analysis of cells targeted by Salmonella type III secretion in vivo

The type III secretion systems (TTSS) encoded in Salmonella pathogenicity island-1 and -2 (SPI-1 and -2) are virulence factors required for specific phases of Salmonella infection in animal hosts. However, the host cell types targeted by the TTSS have not been determined. To investigate this, we have constructed translational fusions between the ß-lactamase reporter and a broad array of TTSS effectors secreted via SPI-1, SPI-2, or both. Secretion of the fusion protein to a host cell was determined by cleavage of a specific fluorescent substrate. In cultured cells, secretion of all six effectors could be observed. However, two to four days following i.p. infection of mice, only effectors secreted by SPI-2 were detected in spleen cells. The cells targeted were identified via staining with nine different cell surface markers followed by FACS analysis as well as by conventional cytological methods. The targeted cells include B and T lymphocytes, neutrophils, monocytes, and dendritic cells, but not mature macrophages. To further investigate replication in these various cell types, Salmonella derivatives were constructed that express a red fluorescent protein. Bacteria could be seen in each of the cell types above; however, most viable bacteria were present in neutrophils. We find that Salmonella is capable of targeting most phagocytic and non-phagocytic cells in the spleen but has a surprisingly high preference for neutrophils. These findings suggest that Salmonella specifically target splenic neutrophils presumably to attenuate their microbicidal functions, thereby promoting intracellular survival and replication in the mouse.

Bacteria of the Salmonella genus are important human pathogens and a leading cause of food-borne illness. Salmonella species' ability to cause disease relies on the activities of two sophisticated molecular syringes that allow the bacteria to pump proteins into cells that they infect. The activities of these syringes have been studied extensively in cells grown under laboratory conditions and shown to be essential for the infectious process in animal models. However, the specific cells within infected organs that are targeted by these syringes have not been identified. In this work we describe the specific spleen cells targeted by Salmonella in the mouse. We find that Salmonella is capable of targeting most cell types using their molecular syringes. Quite surprisingly, we find that Salmonella mostly targets neutrophils, a cell type not thought to be associated with live Salmonella in host tissues. These findings challenge our current views of Salmonella infection and may lead to new insight for treating the disease.

Vaccination greatly reduces disease, disability, death and inequity worldwide

In low-income countries, infectious diseases still account for a large proportion of deaths, highlighting health inequities largely caused by economic differences. Vaccination can cut health-care costs and reduce these inequities. Disease control, elimination or eradication can save billions of US dollars for communities and countries. Vaccines have lowered the incidence of hepatocellular carcinoma and will control cervical cancer. Travellers can be protected against "exotic" diseases by appropriate vaccination. Vaccines are considered indispensable against bioterrorism. They can combat resistance to antibiotics in some pathogens. Noncommunicable diseases, such as ischaemic heart disease, could also be reduced by influenza vaccination. Immunization programmes have improved the primary care infrastructure in developing countries, lowered mortality in childhood and empowered women to better plan their families, with consequent health, social and economic benefits. Vaccination helps economic growth everywhere, because of lower morbidity and mortality. The annual return on investment in vaccination has been calculated to be between 12% and 18%. Vaccination leads to increased life expectancy. Long healthy lives are now recognized as a prerequisite for wealth, and wealth promotes health. Vaccines are thus efficient tools to reduce disparities in wealth and inequities in health.

High-throughput genotyping of Salmonella enterica serovar Typhi allowing geographical assignment of haplotypes and pathotypes within an urban District of Jakarta, Indonesia

High-throughput epidemiological typing systems that provide phylogenetic and genotypic information are beneficial for tracking bacterial pathogens in the field. The incidence of Salmonella enterica serovar Typhi infection in Indonesia is high and is associated with atypical phenotypic traits such as expression of the j and the z66 flagellum antigens. Utilizing a high-throughput genotyping platform to investigate known nucleotide polymorphisms dispersed around the genome, we determined the haplotypes of 140 serovar Typhi isolates associated with Indonesia. We identified nine distinct serovar Typhi haplotypes circulating in Indonesia for more than 30 years, with eight of these present in a single Jakarta suburb within a 2-year period. One dominant haplotype, H59, is associated with j and z66 flagellum expression, representing a potential pathotype unique to Indonesia. Phylogenetic analysis suggests that H59 z66(+), j(+) isolates emerged relatively recently in terms of the origin of serovar Typhi and are geographically restricted. These data demonstrate the potential of high-throughput genotyping platforms for analyzing serovar Typhi populations in the field. The study also provides insight into the evolution of serovar Typhi and demonstrates the value of a molecular epidemiological technique that is exchangeable, that is internet friendly, and that has global utility.

Vaccination greatly reduces disease, disability, death and inequity worldwide

In low-income countries, infectious diseases still account for a large proportion of deaths, highlighting health inequities largely caused by economic differences. Vaccination can cut health-care costs and reduce these inequities. Disease control, elimination or eradication can save billions of US dollars for communities and countries. Vaccines have lowered the incidence of hepatocellular carcinoma and will control cervical cancer. Travellers can be protected against "exotic" diseases by appropriate vaccination. Vaccines are considered indispensable against bioterrorism. They can combat resistance to antibiotics in some pathogens. Noncommunicable diseases, such as ischaemic heart disease, could also be reduced by influenza vaccination. Immunization programmes have improved the primary care infrastructure in developing countries, lowered mortality in childhood and empowered women to better plan their families, with consequent health, social and economic benefits. Vaccination helps economic growth everywhere, because of lower morbidity and mortality. The annual return on investment in vaccination has been calculated to be between 12% and 18%. Vaccination leads to increased life expectancy. Long healthy lives are now recognized as a prerequisite for wealth, and wealth promotes health. Vaccines are thus efficient tools to reduce disparities in wealth and inequities in health.

A linear plasmid truncation induces unidirectional flagellar phase change in H:z66 positive Salmonella Typhi

The process by which bacteria regulate flagellar expression is known as phase variation and in Salmonella enterica this process permits the expression of one of two flagellin genes, fliC or fljB, at any one time. Salmonella Typhi (S. Typhi) is normally not capable of phase variation of flagellar antigen expression as isolates only harbour the fliC gene (H:d) and lacks an equivalent fljB locus. However, some S. Typhi isolates, exclusively from Indonesia, harbour an fljB equivalent encoded on linear plasmid, pBSSB1 that drives the expression of a novel flagellin named H:z66. H:z66+S. Typhi isolates were stimulated to change flagellar phase and genetically analysed for the mechanism of variation. The phase change was demonstrated to be unidirectional, reverting to expression from the resident chromosomal fliC gene. DNA sequencing demonstrated that pBSSB1 linear DNA was still detectable but that these derivatives had undergone deletion and were lacking fljA(z66) (encoding a flagellar repressor) and fljB(z66). The deletion end-point was found to involve one of the plasmid termini and a palindromic repeat sequence within fljB(z66), distinct to that found at the terminus of pBSSB1. These data demonstrate that, like some Streptomyces linear elements, at least one of the terminal inverted repeats of pBSSB1 is non-essential, but that a palindromic repeat sequence may be necessary for replication.

Serodiagnosis of Salmonella enterica serovar Typhi and S. enterica serovars Paratyphi A, B and C human infections

The aim of this study was to evaluate an immunoassay for the detection of human serum antibodies to the LPS and flagellar antigens of Salmonella Typhi and Salmonella Paratyphi A, B and C, and to the Vi capsular polysaccharide of S. Typhi and S. Paratyphi C. A total of 330 sera were used; these originated from 15 patients who were culture-positive for S. Typhi and 15 healthy controls, together with 300 sera submitted to the Laboratory of Enteric Pathogens for Salmonella serodiagnosis. By SDS-PAGE/immunoblotting, all 15 sera from culture-positive patients had serum antibodies to the 9,12 LPS antigens and 10 had antibodies to the ‘d’ flagellar antigens. Of the 300 reference sera, 22 had antibodies to the 9,12 LPS antigens, one to the 1,4,5,12 LPS antigens and 12 to the 6,7 LPS antigens. Only two sera had antibodies to flagellar antigens, one of which bound to the ‘b’ and the other to the ‘d’ antigen. An ELISA was developed that successfully detected serum antibodies to the Vi capsular polysaccharides, but because of the kinetics of serum antibody production to the Vi, these antibodies may be of limited value in the serodiagnosis of acute infection with S. Typhi and S. Paratyphi C. The immunoassays described here provide a sensitive means of detecting serum antibodies to the LPS, flagellar and Vi antigens of S. Typhi and S. Paratyphi, and constitute a viable replacement for the Widal assay for the screening of sera. The Salmonella serodiagnosis protocols described here are the new standard operating procedures used by the Health Protection Agency's National Salmonella Reference Centre based in the Laboratory of Enteric Pathogens, Colindale, UK.

Cases of typhoid fever imported into England, Scotland and Wales (2000–2003)

Although typhoid fever is no longer endemic in most of the developed world, it remains a major infectious disease in less developed regions and imported cases continue to occur in returning travellers, immigrants or migrant workers. We analysed all 692 isolates of Salmonella enterica subspecies enterica serovar Typhi from cases in England, Scotland and Wales that were sent to the Laboratory of Enteric Pathogens at the Health Protection Agency, Centre for Infections, London, UK between 2000 and 2003. The country of acquisition was known for 416 isolates (60%), and the majority of these (70%) came from India or Pakistan. Overall, 24 countries were listed, mainly in Asia and Africa. A total of 48 phage types were detected, 41% of which were Vi-phage type E1. Antimicrobial susceptibility testing revealed that 22% of isolates were multidrug resistant (MDR) (defined as resistance to chloramphenicol, ampicillin and co-trimoxazole) and 39% were quinolone resistant. A significant number of isolates (n=49) were sensitive to nalidixic acid by disk test but exhibited low-level ciprofloxacin resistance, suggesting a novel mechanism of resistance and reinforcing the need for minimum inhibitory concentration determination. Overall, 13% of isolates were both MDR and likely to show a poor response to a fluoroquinolone. A third-generation cephalosporin (e.g. ceftriaxone) should be considered as empirical therapy in regions of the Indian subcontinent where resistance is now at high levels as well as in patients returning from these areas. This study helps to describe the epidemiology of antimicrobial drug resistance in typhoid fever.

Rapid detection of early typhoid fever in endemic community children by the TUBEX O9-antibody test

Typhoid remains a global public health problem, and quick accurate immunodiagnosis is needed. Here, we examined the performance of the 5-min TUBEX O9-antibody detection kit in 243 outpatients (mostly children and infants) in their first week of fever and 57 healthy subjects in the Bangladesh community. Based on culture results, TUBEX was 91.2% (31/34) sensitive and 82.3% (172/209) specific in febrile subjects. However, specificity was better in nonfebrile healthy subjects (89.5%, 51/57) or in febrile individuals who serologically had dengue fever (90.5%, 57/63), suggesting that some culture-negative febrile individuals could be truly typhoidal. These individuals were also positive in an anti-crude O9 enzyme-linked immunosorbent assay (ELISA) and the Widal test. Regression analysis of the TUBEX and ELISA results showed good concordance between them, better with the combined IgM-IgG ELISA than with IgM alone, suggesting that TUBEX detects IgM antibodies not necessarily by themselves, as previously reported, but with the help of IgG antibodies.

Overlapping epidemiologies of hepatitis A and typhoid fever: the needs of the traveler

Hepatitis A and typhoid fever are endemic infectious diseases in many parts of the world. They share a common, simple mode of transmission--the fecal--oral route-associated with poor hygiene. The low endemicity of both diseases in developed countries, and the rise in travel to exotic destinations for business and leisure, mean that increasing numbers of travelers are being exposed to infection. Effective, established vaccines are available against both diseases, and recently new formulations combining both vaccines in one injection have been licensed. We review the present epidemiologic situation for both diseases, to determine the necessity to routinely vaccinate travelers against both diseases.

Antibacterial susceptibility testing in the clinical laboratory

This article familiarizes the clinician with the principles of bacterial susceptibility testing and reporting to facilitate communication with the clinical microbiology laboratory. The emergence of resistance in nearly all commonly isolated bacterial organisms has highlighted the need for ongoing dialogue between the laboratory and those who use its services.

Cefpodoxime - utility in respiratory tract infections and typhoid fever

Cefpodoxime is a oral third generation cephalosporin active against most of gram positive and gram negative bacteria except Pseudomonas, B. fragilis and Entrococcous. Clinical studies have confirmed efficacy of cefpodoxime in acute otitis media, sinusitis and tosillopharyngitis. Twice daily administration and safety profile increases compliance and decreases failure rate. It has a role as switch over therapy from intravenous ceftriaxone in serious respiratory tract infections (RTIs). In areas where common respiratory pathogens show decreased sensitivity to penicillins and macrolides cefpodoxime can be used as empirical first line therapy in respiratory tract infections. It seems to be a promising molecule in pediatric typhoid fever because of its excellent activity against Salmonella species but clinical trials are limited.