Duodenal string-capsule culture compared with bone-marrow, blood, and rectal-swab cultures for diagnosing typhoid and paratyphoid fever

British Infection Association Guidelines for the Diagnosis and Management of Enteric Fever in England

Enteric fever (EF) is an infection caused by the bacteria called Salmonella Typhi or Paratyphi. Infection is acquired through swallowing contaminated food or water. Most EF in England occurs in people returning from South Asia and other places where EF is common; catching EF in England is rare. The main symptom is fever, but stomach pain, diarrhoea, muscle aches, rash and other symptoms may occur. EF is diagnosed by culturing the bacteria from blood and/or stool in a microbiology laboratory. EF usually responds well to antibiotic treatment. Depending on how unwell the individual is, antibiotics may be administered by mouth or by injection. Over the past several years, there has been an overall increase in resistance to antibiotics used to treat enteric fever, in all endemic areas. Additionally, since 2016, there has been an ongoing outbreak of drug-resistant EF in Pakistan. This infection is called extensively drug-resistant, or XDR, EF and only responds to a limited number of antibiotics. Occasionally individuals develop complications of EF including confusion, bleeding, a hole in the gut or an infection of the bones or elsewhere. Some people may continue to carry the bacteria in their stool for a longtime following treatment for the initial illness. These people may need treatment with a longer course of antibiotics to eradicate infection. Travellers can reduce their risk of acquiring EF by following safe food and water practices and by receiving the vaccine at least a few weeks before travel. These guidelines aim to help doctors do the correct tests and treat patients for enteric fever in England but may also be useful to doctors and public health professionals in other similar countries.

Surface-enhanced Raman spectroscopy analysis of serum samples of typhoid patients of different stages

BACKGROUND

Surface-enhanced Raman spectroscopy (SERS) of body fluids is considered a quick, simple and easy to use method for the diagnosis of disease.

OBJECTIVES

To evaluate rapid, reliable, and non-destructive SERS-based diagnostic tool with multivariate data analysis including principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) for classification of different stages of typhoid on the basis of characteristic SERS spectral features.

METHODS

SERS has been used for analysis of serum samples of different stages of typhoid including early acute stage and late acute stage in comparison with healthy samples, in order to investigate capability of this technique for diagnosis of typhoid. SERS spectral features associated with the biochemical changes taking place during the development of the typhoid fever were analyzed and identified.

RESULTS

The value of area under the receiver operating characteristics (AUROC) for early acute stage versus healthy is 0.87 and that for healthy versus late acute stage is 0.52. PLS-DA classifier model gives values of 100 % for accuracy, sensitivity and specificity, respectively for the SERS spectral data sets of healthy versus early acute stage. Moreover, this classifier model gives values of 91 %, 89 % and 97 % for accuracy, sensitivity and specificity, respectively for the SERS spectral data sets of healthy versus late acute stage.

CONCLUSIONS

Based on preliminary work it is concluded that SERS has potential to diagnose various stages of typhoid fever including early acute and late acute stage in comparison with healthy samples.

The Relationship Between Blood Sample Volume and Diagnostic Sensitivity of Blood Culture for Typhoid and Paratyphoid Fever: A Systematic Review and Meta-Analysis

Background

Blood culture is the standard diagnostic method for typhoid and paratyphoid (enteric) fever in surveillance studies and clinical trials, but sensitivity is widely acknowledged to be suboptimal. We conducted a systematic review and meta-analysis to examine sources of heterogeneity across studies and quantified the effect of blood volume.

Methods

We searched the literature to identify all studies that performed blood culture alongside bone marrow culture (a gold standard) to detect cases of enteric fever. We performed a meta-regression analysis to quantify the relationship between blood sample volume and diagnostic sensitivity. Furthermore, we evaluated the impact of patient age, antimicrobial use, and symptom duration on sensitivity.

Results

We estimated blood culture diagnostic sensitivity was 0.59 (95% confidence interval [CI], 0.54-0.64) with significant between-study heterogeneity (I2, 76% [95% CI, 68%-82%]; P < .01). Sensitivity ranged from 0.51 (95% CI, 0.44-0.57) for a 2-mL blood specimen to 0.65 (95% CI, 0.58-0.70) for a 10-mL blood specimen, indicative of a relationship between specimen volume and sensitivity. Subgroup analysis showed significant heterogeneity by patient age and a weak trend towards higher sensitivity among more recent studies. Sensitivity was 34% lower (95% CI, 4%-54%) among patients with prior antimicrobial use and 31% lower after the first week of symptoms (95% CI, 19%-41%). There was no evidence of confounding by patient age, antimicrobial use, symptom duration, or study date on the relationship between specimen volume and sensitivity.

Conclusions

The relationship between the blood sample volume and culture sensitivity should be accounted for in incidence and next-generation diagnostic studies.

Other Potentially Life-Threatening Conditions with Mucocutaneous Findings (Leptospirosis, Typhoid Fever, Dengue, Diphtheria, Murine Typhus)

There are several conditions with mucocutaneous findings that are potentially life-threatening, particularly in certain vulnerable populations. In this chapter, leptospirosis, typhoid fever, dengue, diphtheria, and murine typhus are reviewed. The disease time course of classic and atypical presentations is detailed to assist making the diagnosis in subtle cases. Associated symptoms are discussed as well as a comparison with disease mimics and differential diagnoses. Key diagnostic features are emphasized, and evidence-based management of each condition is detailed in this chapter.

Role of classic signs as diagnostic predictors for enteric fever among returned travellers: Relative bradycardia and eosinopenia

BACKGROUND

The lack of characteristic clinical findings and accurate diagnostic tools has made the diagnosis of enteric fever difficult. We evaluated the classic signs of relative bradycardia and eosinopenia as diagnostic predictors for enteric fever among travellers who had returned from the tropics or subtropics.

METHODS

This matched case-control study used data from 2006 to 2015 for culture-proven enteric fever patients as cases. Febrile patients (>38.3°C) with non-enteric fever, who had returned from the tropics or subtropics, were matched to the cases in a 1:3 ratio by age (±3 years), sex, and year of diagnosis as controls. Cunha's criteria were used for relative bradycardia. Absolute eosinopenia was defined as an eosinophilic count of 0/μL.

RESULTS

Data from 160 patients (40 cases and 120 controls) were analysed. Cases predominantly returned from South Asia (70% versus 18%, p <0.001). Relative bradycardia (88% versus 51%, p <0.001) and absolute eosinopenia (63% versus 38%, p = 0.008) were more frequent in cases than controls. In multivariate logistic regression analysis, return from South Asia (aOR: 21.6; 95% CI: 7.17-64.9) and relative bradycardia (aOR: 11.7; 95% CI: 3.21-42.5) were independent predictors for a diagnosis of enteric fever. The positive likelihood ratio was 4.00 (95% CI: 2.58-6.20) for return from South Asia, 1.72 (95% CI: 1.39-2.13) for relative bradycardia, and 1.63 (95%CI: 1.17-2.27) for absolute eosinopenia. The negative predictive values of the three variables were notably high (83-92%);. however, positive predictive values were 35-57%.

CONCLUSIONS

The classic signs of relative bradycardia and eosinopenia were not specific for enteric fever; however both met the criteria for being diagnostic predictors for enteric fever. Among febrile returned travellers, relative bradycardia and eosinopenia should be re-evaluated for predicting a diagnosis of enteric fever in non-endemic areas prior to obtaining blood cultures.

Bilateral Salmonella Septic Arthritis of the Hip in a Patient with Crohn Disease: A Case Report

CASE

A 27-year-old immunocompromised man with Crohn disease presented with bilateral septic hip arthritis due to Salmonella enterica serotype Typhi. The diagnosis was confirmed by synovial membrane and effusion culture specimens that were obtained during arthroscopic debridement of both hips.

CONCLUSION

Prolonged antimicrobial therapy, bilateral femoral head resection, and placement of cement spacers for 5 months, followed by bilateral total hip arthroplasty, was a radical and effective treatment for a patient with Crohn disease and bilateral Salmonella septic arthritis of the hip.

Protecting Travelers from Typhoid Fever

Typhoid fever is unique to humans. It remains a significant health problem in many developing countries, and poses a risk to travelers who visit such endemic regions. The proportion of cases acquired in foreign countries has continued to rise, reaching 70% in 1984. The risk of typhoid fever should not be underestimated as a travel-related illness.

The incidence of typhoid fever in the united states has decreased from one case per 100,00 population in 1955 to about 0.2 cases per 100,000 in 1966, and has since remained the same. However, international travelers account for more than two-thirds of the reported cases. The percentage of imported cases increased from 33% during 1967 through 1972, to 70% during 1983 through 1984. The majority of the imported cases were from mexico (39%) and india (15%). During the decade 1975 through 1984, 43% of travel-associated cases were non-U.S. citizens. the risk of acquiring typhoid varied from country to country and was the highest for travelers to india and pakistan, with over 400 cases per million, compared with mexico, with 34 per million, and europe, with 0.6 cases per million travelers.

Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections

Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica, initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015.

The Role of the spv Genes in Salmonella Pathogenesis

Salmonella strains cause three main types of diseases in people: gastroenteritis, enteric (typhoid) fever, and non-typhoid extra-intestinal disease with bacteremia. Genetic analysis indicates that each clinical syndrome requires distinct sets of virulence genes, and Salmonella isolates differ in their constellation of virulence traits. The spv locus is strongly associated with strains that cause non-typhoid bacteremia, but are not present in typhoid strains. The spv region contains three genes required for the virulence phenotype in mice: the positive transcriptional regulator spvR and two structural genes spvB and spvC. SpvB and SpvC are translocated into the host cell by the Salmonella pathogenicity island-2 type-three secretion system. SpvB prevents actin polymerization by ADP-ribosylation of actin monomers, while SpvC has phosphothreonine lyase activity and has been shown to inhibit MAP kinase signaling. The exact mechanisms by which SpvB and SpvC act in concert to enhance virulence are still unclear. SpvB exhibits a cytotoxic effect on host cells and is required for delayed cell death by apoptosis following intracellular infection. Strains isolated from systemic infections of immune compromised patients, particularly HIV patients, usually carry the spv locus, strongly suggesting that CD4 T cells are required to control disease due to Salmonella that are spv positive. This association is not seen with typhoid fever, indicating that the pathogenesis and immunology of typhoid have fundamental differences from the syndrome of non-typhoid bacteremia.

The comparison of cultures, widal agglutination test and polymerase chain reaction as a diagnostic tool in typhoid fever

Typhoid fever caused by Salmonella typhi, paratyphi A and B, is an important cause of morbidity and mortality in many developing countries. A rapid and sensitive method for the detection of S. typhi is essential for early diagnosis of typhoid fever and effective therapy. In this study 45 febrile patients who were suspected to have enteric fever were enrolled, and the results of blood cultures, widal agglutination tests and Polymerase Chain Reaction in these cases were evaluated. Group I consisted of 11 patients with diseases other than salmonella infections, group II represented 6 patients with positive cultures, and group III represented 28 patients with negative blood cultures negative but who were clinically suspected cases that had a medical history of using variable antimicrobial agents. Two positive PCR results were present; one of them was in culture positive group (16,6%) and the other was in culture negative group (3,5%). In our study widal agglutination tests and cultures were found not to be helpful in differential dignosis. Although PCR based detection of S. typhi is reported to be a sensitive and specific test for the diagnosis of enteric fever, in our study the benefit of this method in the diagnosis of especially patients who were treated with antimicrobial therapy was not clearly determined. Other methods to increase sensitiviy and specificity to levels such as those of real time PCR should be developed and large-scaled studies should be done in endemic and non-epidemic regions.

Optimizing typhoid fever case definitions by combining serological tests in a large population study in Hechi City, China

Blood culture-based diagnosis can only detect a fraction of the total burden of Salmonella enterica subsp. enterica serovar Typhi. The objective of the study was to detect additional typhoid fever cases through serological tests. A total of 1732 prolonged fever episodes were evaluated using three serological tests, Widal, Tubex and Typhidot-M in a typhoid fever endemic area of southern China. A case definition which included a positive Widal test (TO>or=80 & TH>A), a positive Tubex test (>or=4) and a positive Typhidot-M test, increased the detection of cases by more than twofold from 13 to 28 cases. The case definition has a specificity of 100% and a sensitivity of 39%. Case definitions based on combinations of serological tests can detect additional typhoid fever cases with higher specificity than a single serological test. Improved case detection is essential to understand the true disease burden and can help to boost the power of intervention trials.

A simple validated prediction rule to diagnose typhoid fever in Turkey

The goal of this study was to develop a simple prediction rule for the diagnosis of typhoid fever. A model for the prediction of patients with typhoid fever at hospital admission was derived and validated by assigning weighted point values to independent predictive factors associated with a diagnosis of typhoid fever at hospital admission. Patient demographic, clinical and laboratory variables were used to compare patients with blood culture-confirmed typhoid fever with patients with fever of unknown origin. The model was derived and validated in two separate cohorts of patients from Dicle University Hospital in Diyarbakir, Turkey. A total of 371 patients were enrolled. A diagnostic index score was created using seven independent predictive factors associated with typhoid fever at hospital admission: age <30 years, abdominal distention, confusion, leukopenia, relative bradycardia, positive Widal test and a typhoid tongue. A clinical prediction rule helped to differentiate patients with typhoid fever.

Detection of Salmonella typhi by polymerase chain reaction: implications in diagnosis of typhoid fever

The present study was conducted to detect Salmonella typhi by polymerase chain reaction (PCR) in a clinical setting. A group of 40 clinically suspected cases of typhoid fever, lasting for about 3-11 days, with or without chills and rigors and hepatosplenomegaly were selected. Of these, 20 were culture positive and the remaining 20 were found to be negative by conventional blood culture technique. Primary PCR was followed by nested PCR using two sets of primers corresponding to flagellar gene of S. typhi strain. Two bands of about 458 and 343 bp were detected in 20 blood culture positive cases and 12 of the 20 culture negative ones. In the simulated group of samples, no amplification was detected. Our results suggest that PCR-based diagnosis is particularly useful for all clinically suspected cases of typhoid fever. The sensitivity of PCR and its potential use in routine diagnosis and epidemiological studies of typhoid fever can be exploited to complement studies by including bone marrow culture, faeces and bile samples.

Differentiation of typhoid fever from fulminant hepatic failure in patients presenting with jaundice and encephalopathy

OBJECTIVE

To determine the clinical and laboratory features that allow the early diagnosis of typhoid fever in patients who present with jaundice and encephalopathy.

PATIENTS AND METHODS

This 12-month prospective study, conducted in Bangalore, India, between 1990 and 1991, evaluated the clinical and laboratory features of all patients (N=47) who presented with encephalopathy within 8 weeks of onset of jaundice. Ciprofloxacin and dexamethasone were used to treat 11 patients diagnosed on blood culture as having typhoid fever. The other 36 patients were presumed to have fulminant hepatic failure with a viral cause and were treated with supportive measures (bioartificial liver support and transplantation were not available).

RESULTS

In patients with jaundice and encephalopathy, a liver span of greater than 9 cm on physical examination, thrombocytopenia, elevated alkaline phosphatase level, aspartate aminotransferase level greater than alanine aminotransferase level, and only mild prolongation of the prothrombin time suggested a diagnosis of typhoid fever. All 11 patients diagnosed as having typhoid fever had an excellent response to treatment with ciprofloxacin and dexamethasone with no mortality and with normalization of the liver test results in 2 weeks. On the other hand, 30 of the 36 patients with nontyphoid fulminant hepatic failure died.

CONCLUSIONS

In patients presenting with jaundice and encephalopathy, physical examination and simple laboratory tests can help make an early diagnosis of typhoid fever. We believe that patients with a presumptive diagnosis of typhoid fever should be treated with ciprofloxacin and dexamethasone, even before the results of blood cultures are available.

Clinical application of a dot blot test for diagnosis of enteric fever due to Salmonella enterica serovar typhi in patients with typhoid fever from Colombia and Peru

Clinical application of a dot blot test to detect immunoglobulin G (IgG) (88% sensitivity and specificity) and IgM (12.1% sensitivity and 97% specificity) against flagellar antigen from Salmonella enterica serovar Typhi was performed in Peruvian and Colombian patients with typhoid fever. This test can be used as a good predictor of serovar Typhi infection in regions lacking laboratory facilities and in field studies.

Value of a single-tube widal test in diagnosis of typhoid fever in Vietnam

The diagnostic value of an acute-phase single-tube Widal test for suspected typhoid fever was evaluated with 2,000 Vietnamese patients admitted to an infectious disease referral hospital between 1993 and 1998. Test patients had suspected typhoid fever and a blood culture positive for Salmonella typhi (n= 1,400) or Salmonella paratyphi A (n = 45). Control patients had a febrile illness for which another cause was confirmed (malaria [n = 103], dengue [n = 76], or bacteremia due to another microorganism [n = 156] or tetanus (n = 265). An O-agglutinin titer of >/=100 was found in 18% of the febrile controls and 7% of the tetanus patients. Corresponding values for H agglutinins were 8 and 1%, respectively. The O-agglutinin titer was >/=100 in 83% of the blood culture-positive typhoid fever cases, and the H-agglutinin titer was >/=100 in 67%. The disease prevalence in investigated patients in this hospital was 30.8% (95% confidence interval, 26.8 to 35.1%); at this prevalence, an elevated level of H agglutinins gave better positive predictive values for typhoid fever than did O agglutinins. With a cutoff titer of >/=200 for O agglutinin or >/=100 for H agglutinin, the Widal test would diagnose correctly 74% of the blood culture-positive cases of typhoid fever. However, 14% of the positive results would be false-positive, and 10% of the negative results would be false-negative. The Widal test can be helpful in the laboratory diagnosis of typhoid fever in Vietnam if interpreted with care.

Quantitation of bacteria in blood of typhoid fever patients and relationship between counts and clinical features, transmissibility, and antibiotic resistance

Salmonella typhi was isolated from 369 and Salmonella paratyphi A was isolated from 6 of 515 Vietnamese patients with suspected enteric fever. Compared with conventional broth culture of blood, direct plating of the buffy coat had a diagnostic sensitivity of 99.5% (95% confidence interval [CI], 97.1 to 100%). Blood bacterial counts were estimated by the pour plate method. The median S. typhi count in blood was 1 CFU/ml (range, <0.3 to 387 CFU/ml), of which a mean of 63% (95% CI, 58 to 67%) were intracellular. The mean number of bacteria per infected leukocyte was 1.3 (interquartile range [IQR], 0.7 to 2.4) CFU/cell (n = 81). Children (< 15 years old; n = 115) had higher median blood bacterial counts than adults (n = 262): 1.5 (range, <0.3 to 387) versus 0.6 (range, <0.3 to 17.7) CFU/ml (P = 0.008), and patients who excreted S. typhi in feces had higher bacteremias than those who did not: a median of 3 (range, <0.3 to 32) versus 1 (range, <0.3 to 68) CFU/ml (P = 0.02). Blood bacterial counts declined with increasing duration of illness (P = 0.002) and were higher in infections caused by multidrug-resistant S. typhi (1.3 [range, <0.3 to 387] CFU/ml; n = 313) than in infections caused by antibiotic-sensitive S. typhi (0.5 [range, <0.3 to 32] CFU/ml; n = 62) (P = 0.006). In a multivariate analysis this proved to be an independent association, suggesting a relationship between antibiotic resistance and virulence in S. typhi.

Clinical definition for invasive Salmonella infection in African children

BACKGROUND

Invasive salmonellosis is common among children in tropical Africa, typically presenting as a nonspecific febrile illness that is difficult to distinguish clinically from malaria. This study examines the performance of a clinical definition devised to aid its recognition among children ages 1 to 15 years presenting to a mission hospital in rural Zaire.

METHODS

Invasive salmonellosis was defined by: (1) illness requiring admission to hospital in the opinion of an experience pediatrician; (2) history of fever for 5 or more days; (3) no focus of infection on clinical examination; and (4) negative or only scanty positive thick film for malarial parasites. Children fulfilling all these criteria were treated with ciprofloxacin after culture of blood and feces. The primary outcome measure was blood culture-confirmed salmonellosis. Secondary measures were final clinical diagnosis and serologic evidence of recent salmonellosis.

RESULTS

Of 120 children fulfilling the definition, 55 (46%) were bacteremia; in 46 (38%) Salmonella species were isolated. In the majority of the nonbacteremic children no definite cause for the fever could be found. Salmonella serology supported invasive salmonellosis as the diagnosis in 62% of the nonbacteremic children.

CONCLUSION

Salmonella serology suggested that invasive salmonellosis without detectable bacteremia was common. The addition of blood culture-proved and serologically diagnosed cases indicates that the definition has a specificity of at least 60%.

Risk Factors for Typhoid Fever in Travelers

Background: The incidence of typhoid fever in the developing world remains high and has been estimated at 540 cases per 100,000 of the population per year. International travelers to such areas are at risk of infection, especially if they travel under low hygienic standards. Methods: In order to identify the risk factors leading to infection in travelers and expatriates, travel histories, anamnestic and clinical features of 31 patients with typhoid fever, who presented to a German travel clinic, were investigated. Results: Compared to the total patient population of the outpatient clinic during the period of investigation (n = 17,029 patients), patients who presented with typhoid fever were older (39 years versus 31 years, p <.001) and traveled longer (58 days versus 19 days, p <.001). While only 19.2% of the total patient population had traveled to the Indian subcontinent prior to referral, 35.4% of the patients with typhoid fever had acquired the infection there (p <.001). Similar results were obtained for South East Asia and Indonesia: twenty percent of the total patient population traveled there in contrast with 32.2% of patients with typhoid fever (p <.001). Latin America was visited by 16.3% of all patients, but only 6.4% of patients with typhoid (p <.001).

Diagnosis of typhoid fever by detection of Salmonella typhi antigen in urine

A monoclonal antibody specific for group D Salmonella antigen 9 was used in an indirect enzyme-linked immunosorbent assay (ELISA) for detecting the antigen in urine specimens collected from patients with clinical typhoid fever in Jakarta, Indonesia. The ELISA had a sensitivity of 95% in identifying patients in whom Salmonella typhi was isolated from hemocultures, 73% in patients in whom S. typhi was isolated from stool specimens, and 40% in patients in whom the organism was isolated from bone marrow cultures. Among patients in whom S. typhi was isolated from blood cultures, the ELISA had a sensitivity of 65% when a single urine specimen was examined and 95% when serially collected urine specimens were examined. A dot blot immunoassay performed on a nitrocellulose filter in parallel had a sensitivity of 85%, versus 83% for the plate ELISA in which S. typhi was isolated from blood, bone marrow, and/or stool specimens. Since S. typhi antigen is intermittently excreted in the urine of patients with typhoid fever, serially collected urine from patients with typhoid should be tested for antigen 9.

Oral immunisation against typhoid fever in Indonesia with Ty21a vaccine

When tested under conditions of moderate transmission of typhoid fever, a liquid formulation of the oral typhoid fever vaccine Ty21a had a protective efficacy of 96% in Egypt, and an enteric coated capsule formulation had an efficacy of 67% in Chile. We compared the two formulations under conditions of intense transmission of typhoid fever in Indonesia in a randomised, double-blind trial. 20,543 subjects (age range 3-44 years) received either three doses of enteric coated capsules containing placebo or live Ty21a, or three doses of lyophilised placebo or live Ty21a reconstituted with phosphate buffer. During 30 months of follow-up, the rate of blood-culture-positive typhoid fever among controls was 810/100,000 per year. Rates of typhoid fever were 379/100,000 per year for subjects who received the liquid formulation of vaccine and 468/100,000 per year for subjects who received enteric coated capsules. The protective efficacies of the liquid and enteric coated formulations were 53% and 42%, respectively. Neither formulation protected against infection with Salmonella paratyphi A. No major side-effects were noted, but the overall incidence of side-effects was greater in the vaccine groups. Under conditions of intense transmission, Ty21a protected against typhoid fever; however, because Ty21a will not protect all individuals, there is a need for additional approaches to prevent the disease.

Protecting travelers from typhoid fever

Although the incidence of domestically acquired typhoid fever is declining, the proportion of cases resulting from foreign travel has continued to rise. The widely available heat-phenol-inactivated parenteral vaccine has an efficacy of 65% but evokes severe adverse reactions in approximately 25% of recipients. A major advance in the control of typhoid fever was the development of an oral live, attenuated vaccine. Three doses of Ty21a in an enteric coated formulation given over one week provides 69% efficacy for at least four years. A series of four doses confers maximum protection. Increasing the interval between doses does not improve protection. Vaccine should be refrigerated and is currently not recommended for pregnant women, children older than 6 years of age, or immunocompromised patients. With respect to vaccines that are not available in the United States, parenteral purified Vi polysaccharide is considered safe and provides 64% to 72% protection over 21 months. Lastly, the safety and immunogenicity of an auxotrophic (Aro-, Pur-) S typhi recently has been evaluated. Travelers to areas of high risk should be vaccinated but must be cautioned that vaccination is not a substitute for careful selection of food and water. Since typhoid vaccines are not 100% effective, the protection of the vaccine can be overcome by large inocula of S typhi. Physicians caring for world travelers must also keep in mind that other infections, such as plague, typhus, and arboviral fever, may mimic a typhoidal pattern.

The use of bone marrow culture for the diagnosis of melioidosis

We have evaluated prospectively the contribution of bone marrow culture to the diagnosis of melioidosis. Bone marrow (BMC) and blood cultures (BC) were collected concurrently from 105 patients with suspected acute, severe melioidosis. 67 patients were subsequently proved to have the disease whilst other significant organisms were isolated from these specimens in 5 cases. Overall, 67.2% of BC and 64.2% of BMC from melioidosis patients grew Pseudomonas pseudomallei. Time to positivity did not differ significantly in paired BC and BMC specimens. These results do not support the routine use of BMC in the diagnosis of acute, severe melioidosis. In one patient with pulmonary melioidosis, however, blood cultures were repeatedly negative, whilst bone marrow grew P. pseudomallei, and this preceded the development of a distant focus of infection. This suggests that culture of bone-marrow may be of value in certain blood culture-negative patients with melioidosis.

Rapid diagnosis of typhoid fever through identification of Salmonella typhi within 18 hours of specimen acquisition by culture of the mononuclear cell-platelet fraction of blood

Detection of Salmonella typhi in blood by culture of the mononuclear cell-platelet layer was compared with other methods currently used for the diagnosis of typhoid fever. Colonies of S. typhi were present in all mononuclear cell-platelet layer-positive cultures within 18 h of plating and were identified within an additional 10 min by a coagglutination technique. In contrast, identification of all positive cultures by conventional blood culture required 3 days.

Use of a DNA probe to detect Salmonella typhi in the blood of patients with typhoid fever

A DNA probe was used to detect Salmonella typhi from blood samples from 14 of 33 patients with culture-confirmed typhoid fever, using the equivalent of 2.5 ml of blood. In contrast, S. typhi was detected in 17 of the same 33 patients by culture of 8 ml of blood. The probe hybridized to blood samples of 4 of 47 patients from whom S. typhi was not isolated.

General considerations in the management of typhoid fever and dysentery

Typhoid fever is diagnosed on the basis of isolation of Salmonella typhi from blood, bone marrow, or bile. S. typhi found in stool or urine may reflect chronic asymptomatic carriage. Although antimicrobial therapy may not eliminate carriage, it is effective for the treatment of clinically evident acute disease. Among the drugs currently available, chloramphenicol is the most widely used. Chloramphenicol is effective and inexpensive, but it is associated with a 3% rate of chronic carriage, a high relapse rate, and, in rare cases, aplastic anemia. For these reasons, and because of the emergence of chloramphenicol-resistant strains of S. typhi, alternative drugs need to be considered. Dysentery is characterized by the passage of unformed stools that commonly contain blood and mucus and in which large numbers of leukocytes can be detected on microscopic examination. Invasion of the intestinal epithelium is the distinguishing characteristic, and Shigella sp are the most frequent cause. Although oral rehydration is useful in dehydrated patients, dehydration is not a common problem in acute dysentery, and antimicrobial treatment is indicated for this disease. An antimicrobial agent should be selected on the basis of knowledge of the susceptibility patterns of locally isolated Shigella strains.

Waterborne typhoid fever in Haifa, Israel: clinical, microbiologic, and therapeutic aspects of a major outbreak

A major outbreak of waterborne typhoid fever involving 77 verified cases occurred in 1985 in a large suburban area of Haifa, Israel. The authors summarize the clinical, microbiologic, and therapeutic aspects of these patients. Fever, usually higher than 39 degrees C, was the hallmark of the disease. Other manifestations of typhoid, although relatively frequent, are presented as part of a mild nonspecific symptom complex, often found only in the prodromal period. An elevated level of serum glutamic-oxaloacetic transaminase (mean, 81 IU/ml) was the most characteristic laboratory abnormality, occurring in 94% of the patients. Blood cultures were positive in 46 of the 50 patients (92%), and were not affected by prior outpatient antibiotic therapy. The first blood culture was diagnostic in 93% of the cases. Although fever tended to disappear more rapidly among patients receiving ampicillin than among those treated with chloramphenicol, results of therapy were similar in both groups. Nevertheless, the relapse rate of 36% among 25 chloramphenicol-treated patients was significantly higher than the 9% noted among 22 patients treated with ampicillin. Except for one case of hemolytic anemia, serious complications were conspicuously absent, and outcomes were uniformly favorable.

Streptokinase clot culture compared with whole blood culture for isolation of Salmonella typhi and S. paratyphi A from patients with enteric fever

The sensitivities of whole blood and clot cultures were compared in 155 patients with typhoid or paratyphoid fever. Salmonella typhi or S. paratyphi A were isolated from 98.7% of 5 ml 1:10 blood:broth ratio blood cultures and 94.8% of 5 ml streptokinase clot cultures (P greater than 0.05). There was no difference in the speed of isolation. Whole blood culture and clot culture were of nearly equal sensitivity in this group of patients.

Safety, infectivity, immunogenicity, and in vivo stability of two attenuated auxotrophic mutant strains of Salmonella typhi, 541Ty and 543Ty, as live oral vaccines in humans

Two Salmonella typhi mutants, 541Ty (Vi+) and 543Ty (Vi-), auxotrophic for p-aminobenzoate and adenine, were evaluated as live oral vaccines. 33 volunteers ingested single doses of 10(8), 10(9), or 10(10) vaccine organisms, while four others received two 2 X 10(9) organism doses 4 d apart. No adverse reactions were observed. Vaccine was recovered from coprocultures of 29 of 37 vaccinees (78%) and from duodenal string cultures of two; repeated blood cultures were negative. The humoral antibody response to S. typhi O, H, Vi, and lysate antigens in serum and intestinal fluid was meager. In contrast, all vaccinees manifested cell-mediated immune responses. After vaccination, 69% of vaccinees overall and 89% of recipients of doses greater than or equal to 10(9) responded to S. typhi particulate or purified O polysaccharide antigens in lymphocyte replication studies but not to antigens of other Salmonella or Escherichia coli. All individuals, postvaccination, demonstrated a significant plasma-dependent mononuclear cell inhibition of wild S. typhi.

Evaluation of blood clot cultures for isolation of Salmonella typhi, Salmonella paratyphi-A, and Brucella melitensis

Two types of clot culture, one with taurocholate-streptokinase and the other with bile as a culture medium, and two conventional cultures of whole blood were evaluated in parallel in an area where typhoid fever and brucellosis are endemic. Each of the four systems contained 5 ml of blood or the clot derived from 5 ml of blood and sufficient broth to yield a 1:11 dilution of the specimen. Of 542 patients studied, Salmonella paratyphi-A was isolated from 61, S. typhi from 46, and Brucella melitensis from 30. The two clot cultures yielded the salmonellae equally well; both were superior to whole blood cultured in Trypticase soy broth (P less than 0.02) but not to whole blood cultured in bile (P greater than 0.05). Only two systems were successful for isolation of B. melitensis. Blood-Trypticase soy broth identified 28 (93%), and clot-streptokinase cultures identified 21 (70%) (P greater than 0.05). The data indicate that use of clots per se offers no advantage in sensitivity over procedures which use whole blood. Nonetheless, they are excellent for isolation of enteric fever salmonellae and can be performed with clots left over after serum is removed for serological, biochemical, or other tests.

Identification of enteric pathogens in the small and large intestine of children with diarrhea

Enteric pathogens were identified in children with diarrhea from duodenal specimens obtained with a string capsule and from fecal specimens. Rotavirus was identified in stools of 43 of 100 children, and was recovered from the small intestine from nine (21%) children who were excreting this virus. Shigella was isolated from stools from 22, Salmonella from 17, enterotoxigenic Escherichia coli from eight, and Aeromonas hydrophila from one of 100 children with diarrhea. In contrast to rotavirus, Salmonella, Shigella, enterotoxigenic Escherichia coli, and A. hydrophila were not isolated from the small intestine. Nonenterotoxigenic Aeromonas species were recovered from the small intestine, but not the stool of five children. These children were also infected with Shigella or with rotavirus; this suggests that Aeromonas was not the cause of their diarrhea. None of 51 Escherichia coli isolated with the string capsules, or 67 isolated from stool that agglutinated in commercial enteropathogenic Escherichia coli antisera were of classical enteropathogenic Escherichia coli serotypes. One hundred and five of these 118 Escherichia coli did not hybridize with a deoxyribonucleic acid probe for plasmid mediated factors conferring adherence to HeLa cells. Examination of specimens collected with a string capsule from children with diarrhea did not identify any more enteric pathogens than examining stools. Furthermore testing Escherichia coli for agglutination in commercial enteropathogenic Escherichia coli antisera did not identify Escherichia coli of enteropathogenic serotypes.

Management of typhoid

Typhoid fever is still a major problem in developing Third World countries where socioeconomic conditions and standards of hygiene are still well below standard. Prophylaxis is far from satisfactory. However, recent developments using live oral vaccines are encouraging. Specific treatment for the disease consists of chloramphenicol or co-trimoxazole; amoxycillin and ampicillin are inferior agents but are of value in several situations because their potential toxic effects are less marked. Most other agents also have drawbacks or are relatively ineffective. In the severely toxic patient, corticosteroids seem to affect prognosis favourably. Of the many other acute complications of typhoid fever, ileal perforation is the most serious; there is still controversy concerning the respective roles of conservative and surgical management, but it is clear that individual cases must be assessed on their merit. Amoxycillin, because it is very rapidly absorbed and produces very high blood concentrations, is probably the best antibiotic for the carrier state.