Current trends in typhoid Fever

From Eberthella typhi to Salmonella Typhi: The Fascinating Journey of the Virulence and Pathogenicity of Salmonella Typhi

Salmonella Typhi (S. Typhi), the invasive typhoidal serovar of Salmonella enterica that causes typhoid fever in humans, is a severe threat to global health. It is one of the major causes of high morbidity and mortality in developing countries. According to recent WHO estimates, approximately 11-21 million typhoid fever illnesses occur annually worldwide, accounting for 0.12-0.16 million deaths. Salmonella infection can spread to healthy individuals by the consumption of contaminated food and water. Typhoid fever in humans sometimes is accompanied by several other critical extraintestinal complications related to the central nervous system, cardiovascular system, pulmonary system, and hepatobiliary system. Salmonella Pathogenicity Island-1 and Salmonella Pathogenicity Island-2 are the two genomic segments containing genes encoding virulent factors that regulate its invasion and systemic pathogenesis. This Review aims to shed light on a comparative analysis of the virulence and pathogenesis of the typhoidal and nontyphoidal serovars of S. enterica.

Chitosan/halloysite nanotubes microcomposites: A double header approach for sustained release of ciprofloxacin and its hemostatic effects

Clotting time of lower gastro intestinal bleeding (LGIB) can be reduced by using simple, cost-effective, and naturally occurring halloysite nanotubes (HNTs). The present study aimed to decrease the clotting time by the application of chitosan (CHT) and its microcomposites (MCs) prepared by suspension emulsification technique with HNTs (CHT/HNTs MC). Physicochemical properties, X-Ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and percentage release of ciprofloxacin from CHT/HNTs MCs was evaluated. In-vitro procoagulant activity of CHT, HNTs and their complexes CHT/HNTs MCs was performed on rabbit blood which was confirmed by a rat tail amputation. Direct relation of HNTs was observed for the whole-blood clotting kinetics i.e., 2% HNTs showed a maximum 66.0% increase in the clotting ability as compared with pure CHT. Interestingly, rat-tail amputation studies showed comparative results of CHT, HNTs, and CHT/HNTs MCs. A total of 75% permeation of ciprofloxacin of CHT/HNTs MCs on rat intestinal membrane was observed within 3 h, confirming their SR behavior. Furthermore, improved hemostatic and clotting properties were CHT/HNTs MC₁ > CHT/HNTs MC₂ > CHT/HNTs MC₃ > CHT > HNTs, respectively. Thus, it provided the control of bleeding disorders in LGIB with any antibacterial agents, particularly ciprofloxacin.

Acute Generalized Peritonitis in a Peripheral Hospital Centre in Benin: Can It Be Managed by a Local General Practitioner?

Background

Acute generalized peritonitis in resource-poor countries is still a health challenge due to late diagnosis, surgical delay, and specialists' unavailability. These are the foremost determinants of surgical morbidity and mortality. We report the experience of a peripheral hospital in Benin not equipped with specialized surgeons.

Methods

This is an observational, retrospective, and descriptive study including patients operated for acute generalized peritonitis at the Atacora Departmental Hospital Centre, Benin, where unfortunately CT scan and intensive care unit are still not available. Most of surgical activities were performed by a general practitioner with previous surgical training (but no surgical specialization). Age, gender, cause of peritonitis, surgical procedures, and postoperative outcome were evaluated.

Results

Sixty-three patients were included. The mean age was 23.2 years and sex ratio M/F 1.5. The mean surgical delay was 26 hours (range: 6–92 hours). An ileal typhoid perforation was found in 40 patients (63.5%), and 35 of them (87.5%) underwent a primary perforation repair without bowel resection. 73% of surgical procedures were performed by the general practitioner. Morbidity was 34.9% and mortality was 14.3%. The average postoperative hospital stay was 12 days (range: 11–82 days). These results were comparable to those observed in the subgroup of patients (17 cases) operated by the general surgeons (morbidity 32.6%, mortality 13.0%, and average postoperative hospital stay 11 days, range: 1–58 days).

Conclusion

Acute generalized peritonitis requires urgent management, and it can be effectively carried out, in a context of limited resources, by a general practitioner with surgical skills.

Bacterial Biofilm and its Role in the Pathogenesis of Disease

Recognition of the fact that bacterial biofilm may play a role in the pathogenesis of disease has led to an increased focus on identifying diseases that may be biofilm-related. Biofilm infections are typically chronic in nature, as biofilm-residing bacteria can be resilient to both the immune system, antibiotics, and other treatments. This is a comprehensive review describing biofilm diseases in the auditory, the cardiovascular, the digestive, the integumentary, the reproductive, the respiratory, and the urinary system. In most cases reviewed, the biofilms were identified through various imaging technics, in addition to other study approaches. The current knowledge on how biofilm may contribute to the pathogenesis of disease indicates a number of different mechanisms. This spans from biofilm being a mere reservoir of pathogenic bacteria, to playing a more active role, e.g., by contributing to inflammation. Observations also indicate that biofilm does not exclusively occur extracellularly, but may also be formed inside living cells. Furthermore, the presence of biofilm may contribute to development of cancer. In conclusion, this review shows that biofilm is part of many, probably most chronic infections. This is important knowledge for development of effective treatment strategies for such infections.

Acute scrotal ulcers in typhoid Fever: case report and literature review

Background. In developed countries, typhoid fever is a travel-associated disease that is often overlooked. However, as standard blood and stool culture methods have relatively low sensitivity, diagnosis depends heavily on clinical signs and symptoms and on a high level of suspicion.

Methods. Reported here is the case of an 18-year-old male who presented with fever and acute scrotal ulcers and whose blood cultures were positive for Salmonella enterica serotype Typhi. A review of genital ulcers associated with typhoid fever in the literature is discussed.

Conclusion. This report suggests that typhoid fever is a differential diagnosis of acute genital ulcers.

Histopathological analysis of Salmonella chronic carriage in the mouse hepatopancreatobiliary system

Salmonella Typhi asymptomatic chronic carriage represents a challenge for the diagnosis and prevention of typhoid fever in endemic areas. Such carriers are thought to be reservoirs for further spread of the disease. Gallbladder carriage has been demonstrated to be mediated by biofilm formation on gallstones and by intracellular persistence in the gallbladder epithelium of mice. In addition, both gallstones and chronic carriage have been associated with chronic inflammation and the development of gallbladder carcinoma. However, the pathogenic relationship between typhoid carriage and the development of pre-malignant and/or malignant lesions in the hepatopancreatobiliary system as well as the host-pathogen interactions occurring during chronic carriage remains unclear. In this study, we monitored the histopathological features of chronic carriage up to 1 year post-infection. Chronic cholecystitis and hepatitis ranging from mild to severe were present in infected mice regardless of the presence of gallstones. Biliary epithelial hyperplasia was observed more commonly in the gallbladder of mice with gallstones (uninfected or infected). However, pre-malignant lesions, atypical hyperplasia and metaplasia of the gallbladder and exocrine pancreas, respectively, were only associated with chronic Salmonella carriage. This study has implications regarding the role of Salmonella chronic infection and inflammation in the development of pre-malignant lesions in the epithelium of the gallbladder and pancreas that could lead to oncogenesis.

Limitations of typhoid fever diagnostics and the need for prevention

The study under review evaluated serological tests for typhoid fever against PCR as a reference test. While laboratory testing is essential for the confirmation of this severe disease, the low bacterial load and the low level of specific antibodies in the blood of typhoid patients combined with its acute character make interpretation of laboratory testing cumbersome. Validation of an index test requires good understanding of the diagnostic performance and assay characteristics of the reference test, and criteria and principles for study design and reporting outlined by the Quality Assessment of Diagnostic Accuracy Studies and the Standards for Reporting Studies of Diagnostic Accuracy should be followed. Described PCR assays for typhoid fever have not been validated against bone marrow culture, the gold standard, and their diagnostic utility remains to be established.

Comparative analysis of primary repair vs resection and anastomosis, with laparostomy, in management of typhoid intestinal perforation: results of a rural hospital in northwestern Benin

Background

The objective is to compare primary repair vs intestinal resection in cases of intestinal typhoid perforations. In addition, we hypothesised the usefulness of laparostomy for the early diagnosis and treatment of complications.

Methods

111 patients with acute peritonitis underwent emergency laparotomy: number of perforations, distance of perforations from the ileocaecal valve, and type of surgery performed were recorded. A laparostomy was then created and explored every 48 to 72 hours. The patients were then divided into two groups according to the surgical technique adopted at the initial laparotomy: primary repair (Group A) or intestinal resection with anastomosis (Group B). Clinical data, intraoperative findings, complications and mortality were evaluated and compared for each group.

Results

In 104/111 patients we found intestinal perforations, multiple in 47.1% of patients. 75 had primary repair (Group A) and 26 had intestinal resection with anastomosis (Group B). Group B patients had more perforations than patients in Group A (p = 0.0001). At laparostomy revision, the incidence of anastomotic dehiscence was greater than that of primary repair dehiscence (p = 0.032). The incidence of new perforations was greater in Group B than in Group A (p = 0.01). Group B correlates with a higher morbility and with a higher number of laparostomy revisions than Group A (p = 0.005).

There was no statistical difference in terms of mortality between Group A and Group B. Presence of pus in the abdominal cavity at initial laparotomy correlates with significantly higher mortality (p = 0.0001).

Conclusions

Resection and anastomosis shows greater morbidity than primary repair. Laparostomy revision makes it possible to rapidly identify new perforations and anastomotic or primary repair dehiscences; although this approach may seem aggressive, the number of operations was greater in patients who had a favourable outcome, and does not correlate with mortality.

Comparative analysis of primary repair vs resection and anastomosis, with laparostomy, in management of typhoid intestinal perforation: results of a rural hospital in northwestern Benin

Background

Wireless esophageal pH monitoring system is an important approach for diagnosis of gastroesophageal reflux disease (GERD), the aim of this study is to test the tolerability and utility of the first wireless esophageal pH monitoring system made in China, and evaluate whether it is feasible for clinical application to diagnose GERD.

Methods

Thirty patients from Department of Gastroenterology of The First Affiliated Hospital of Chongqing Medical University who were suspected GERD underwent JSPH-1 pH capsule. The capsule was placed 5 cm proximal to the squamocolumnar junction (SCJ) by endoscopic determination, the data was recorded consecutively for 48 hours. Then all pH data was downloaded to a computer for analysis. The discomforts reported by patients were recorded.

Results

30 patients were placed JSPH-1 pH capsule successfully and completed 24-hour data recording, 29 patients completed 48-hour data recording. One patient complained of chest pain and required endoscopic removal. No complications and interference of daily activities were reported during data monitoring or follow-up period. 48-hour pH monitoring detected 15 patients of abnormal acid exposure, on day1 detected 9 patients, the difference had statistical significance (P<0.01). Positive symptom index (SI) was identified in 3 patients with normal pH data in both 24-hours. In total, 48-hour monitoring increased diagnosis of GERD in 9 patients.

Conclusion

48-hour esophageal pH monitoring with JSPH-1 wireless pH monitoring system is safe, well tolerated and effective. It can be feasible for clinical application to diagnose GERD.

Neurologic manifestations associated with an outbreak of typhoid fever, Malawi--Mozambique, 2009: an epidemiologic investigation

Background

The bacterium Salmonella enterica serovar Typhi causes typhoid fever, which is typically associated with fever and abdominal pain. An outbreak of typhoid fever in Malawi-Mozambique in 2009 was notable for a high proportion of neurologic illness.

Objective

Describe neurologic features complicating typhoid fever during an outbreak in Malawi-Mozambique

Methods

Persons meeting a clinical case definition were identified through surveillance, with laboratory confirmation of typhoid by antibody testing or blood/stool culture. We gathered demographic and clinical information, examined patients, and evaluated a subset of patients 11 months after onset. A sample of persons with and without neurologic signs was tested for vitamin B6 and B12 levels and urinary thiocyanate.

Results

Between March – November 2009, 303 cases of typhoid fever were identified. Forty (13%) persons had objective neurologic findings, including 14 confirmed by culture/serology; 27 (68%) were hospitalized, and 5 (13%) died. Seventeen (43%) had a constellation of upper motor neuron findings, including hyperreflexia, spasticity, or sustained ankle clonus. Other neurologic features included ataxia (22, 55%), parkinsonism (8, 20%), and tremors (4, 10%). Brain MRI of 3 (ages 5, 7, and 18 years) demonstrated cerebral atrophy but no other abnormalities. Of 13 patients re-evaluated 11 months later, 11 recovered completely, and 2 had persistent hyperreflexia and ataxia. Vitamin B6 levels were markedly low in typhoid fever patients both with and without neurologic signs.

Conclusions

Neurologic signs may complicate typhoid fever, and the diagnosis should be considered in persons with acute febrile neurologic illness in endemic areas.

Typhoid intestinal perforations at a University teaching hospital in Northwestern Tanzania: A surgical experience of 104 cases in a resource-limited setting

BACKGROUND

Typhoid intestinal perforation is still prevalent in many developing countries. Despite the advances in the management, the outcome in these patients in resource limited countries is still very poor. This study was to review our experiences on the surgical management of typhoid intestinal perforation and to determine the prognostic factors for mortality in our local setting.

METHODS

This was a combined retrospective and prospective study of patients who were operated for typhoid intestinal perforation at Bugando Medical Centre between August 2006 and September 2011. Data collected were analyzed using SPSS computer software version 15.

RESULTS

A total of 104 patients were studied representing 8.7% of typhoid fever cases. Males were affected twice more than the females (2.6:1). Their ages ranged from 8 to 76 years with a median age of 18.5 years. The peak age incidence was in the 11-20 years age group. Fever and abdominal pain were the most common presenting symptoms and majority of the patients (80.8%) perforated between within 14 days of illness. Chest and abdominal radiographs revealed pneumoperitonium in 74.7% of cases. Ultrasound showed free peritoneal collection in 85.7% of cases. Nine (10.2%) patients were HIV positive with a median CD4+ count of 261 cells/μl. The perforation-surgery interval was more than 72 hours in 90(86.5%) patients. The majority of patients (84.6%) had single perforations and ileum was the most common part of the bowel affected occurring in 86.2% of cases. Simple closure of the perforations was the most commonly performed procedure accounting for 78.8% of cases. Postoperative complication rate was 39.4% and surgical site infection was the most frequent complication in 55.5% of cases. Mortality rate was 23.1% and it was statistically significantly associated with delayed presentation, inadequate antibiotic treatment prior to admission, shock on admission, HIV positivity, low CD4 count (< 200 cells/μl), high ASA classes (III-V), delayed operation, multiple perforations, severe peritoneal contamination and presence of postoperative complications (P < 0.001). The median overall length of hospital stay was 28 days.

CONCLUSION

Typhoid intestinal perforation is still endemic in our setting and carries high morbidity and mortality. This study has attempted to determine the factors that statistically influence mortality in typhoid perforation in our environment. Appropriate measures focusing at these factors are vital in order to deliver optimal care for these patients in this region.

Validation of the Dri-Dot Latex agglutination and IgM lateral flow assays for the diagnosis of typhoid fever in an Egyptian population

Laboratory confirmation of typhoid fever is essential for appropriate medical treatment. Blood culture is a standard test for diagnosis of typhoid fever, but well-equipped diagnostic facilities to perform culture are seldom available in endemic areas. We retrospectively compared 2 diagnostic field tests, a latex agglutination Dri-Dot assay and an IgM Lateral Flow assay, to blood culture, in patients with clinically diagnosed typhoid fever. Sensitivity of the Dri-Dot was 71.4%, and specificity was 86.3% for samples collected at time of first diagnosis. Sensitivity and specificity of IgM Lateral Flow were 80% and 71.4%, respectively. A major limitation of these serologic tests is the limited sensitivity at the early stage of the disease. Performing both tests in parallel increased sensitivity to 84.3%, but decreased specificity to 70.5%. There was a trend towards improved diagnostic performance using either assay over a longer duration of illness. These rapid, point-of-care assays for typhoid fever provide easy-to-interpret results in typhoid-endemic countries and may be most useful in patients presenting 1 week after symptom onset.

Generation of Salmonella-specific Th1 cells requires sustained antigen stimulation

The administration of live attenuated Salmonella strains has proven to be an effective way to generate protective immunity against Salmonella infection in humans and mice. Studies in the mouse model have shown that protection requires Salmonella-specific Th1 cells, however the timing and stimulatory requirements for generating optimal Th1 responses have not been carefully examined. We used antibiotic interruption of vaccination with live attenuated Salmonella to examine the requirements for Salmonella-specific Th1 development and protective immunity. Optimal development of protective immunity to Salmonella infection required at least one week of exposure to the live attenuated Salmonella strain. In contrast, optimal development of Salmonella-specific Th1 cells required two weeks of in vivo colonization. Thus, sustained in vivo stimulation with a live vaccine strain is essential for the development of robust Salmonella-specific Th1 cells.

Dissemination of persistent intestinal bacteria via the mesenteric lymph nodes causes typhoid relapse

Enteric pathogens can cause relapsing infections in a proportion of treated patients, but greater understanding of this phenomenon is hindered by the lack of appropriate animal models. We report here a robust animal model of relapsing primary typhoid that initiates after apparently successful antibiotic treatment of susceptible mice. Four days of enrofloxacin treatment were sufficient to reduce bacterial loads below detectable levels in all major organs, and mice appeared otherwise healthy. However, any interruption of further antibiotic therapy allowed renewed fecal shedding and renewed bacterial growth in systemic tissues to occur, and mice eventually succumbed to relapsing infection. In vivo imaging of luminescent Salmonella identified the mesenteric lymph nodes (MLNs) as a major reservoir of relapsing infection. A magnetic-bead enrichment strategy isolated MLN-resident CD11b(+) Gr-1(-) monocytes associated with low numbers of persistent Salmonella. However, the removal of MLNs increased the severity of typhoid relapse, demonstrating that this organ serves as a protective filter to restrain the dissemination of bacteria during antibiotic therapy. Together, these data describe a robust animal model of typhoid relapse and identify an important intestinal phagocyte subset involved in protection against the systemic spread of enteric infection.

The expanding spectrum of disease due to salmonella: an international perspective

Human disease due to Salmonella infections appears to be on the rise worldwide. Despite the availability of vaccines and generally effective antibiotic therapy, salmonellosis, in the forms of gastroenteritis and enteric fever, remains a major cause of morbidity and mortality in many developing countries, especially in young children and immunocompromised hosts. In certain highly endemic areas of South and Southeast Asia, the emergence of quinolone-resistant and multidrug-resistant strains of Salmonella contribute to the magnitude of the problem. In the United States and Europe, a low but consistent rate of disease appears to be primarily related to ingestion of contaminated poultry, lapses in sanitary agricultural practices, and importation of tainted vegetable products. An improved understanding of the molecular basis of bacterial resistance and improved design and expanded use of vaccines provide hope for containing the spread and reducing morbidity of the international spectrum of disease due to Salmonella pathogens.

Diagnosis of enteric fever in the emergency department: a retrospective study from Pakistan

BACKGROUND

Enteric fever is one of the top differential diagnoses of fever in many parts of the world. Generally, the diagnosis is suspected and treatment is initiated based on clinical and basic laboratory parameters.

AIMS

The present study identifies the clinical and laboratory parameters predicting enteric fever in patients visiting the emergency department of a tertiary care hospital in Pakistan.

METHODS

This is a retrospective chart review of all adult patients with clinically suspected enteric fever admitted to the hospital through the emergency department during a 5-year period (2000-2005).

RESULTS

A total of 421 emergency department patients were admitted to the hospital with suspected enteric fever. There were 53 cases of blood culture-positive enteric fever and 296 disease-negative cases on culture. The mean age in the blood culture-positive group was 27 years (SD: 10) and in the group with negative blood culture for enteric fever, 35 years (SD: 15) with a male to female ratio of 1:0.6 in both groups. Less than half (48%) of all patients admitted with suspected enteric fever had the discharge diagnosis of enteric fever, of which only 13% of the patients had blood culture/serologically confirmed enteric fever. None of the common clinical and laboratory parameters differed between enteric fever-positive patients and those without it.

CONCLUSION

Commonly cited clinical and laboratory parameters were not able to predict enteric fever.

Neglected tropical diseases in sub-saharan Africa: review of their prevalence, distribution, and disease burden

The neglected tropical diseases (NTDs) are the most common conditions affecting the poorest 500 million people living in sub-Saharan Africa (SSA), and together produce a burden of disease that may be equivalent to up to one-half of SSA's malaria disease burden and more than double that caused by tuberculosis. Approximately 85% of the NTD disease burden results from helminth infections. Hookworm infection occurs in almost half of SSA's poorest people, including 40-50 million school-aged children and 7 million pregnant women in whom it is a leading cause of anemia. Schistosomiasis is the second most prevalent NTD after hookworm (192 million cases), accounting for 93% of the world's number of cases and possibly associated with increased horizontal transmission of HIV/AIDS. Lymphatic filariasis (46-51 million cases) and onchocerciasis (37 million cases) are also widespread in SSA, each disease representing a significant cause of disability and reduction in the region's agricultural productivity. There is a dearth of information on Africa's non-helminth NTDs. The protozoan infections, human African trypanosomiasis and visceral leishmaniasis, affect almost 100,000 people, primarily in areas of conflict in SSA where they cause high mortality, and where trachoma is the most prevalent bacterial NTD (30 million cases). However, there are little or no data on some very important protozoan infections, e.g., amebiasis and toxoplasmosis; bacterial infections, e.g., typhoid fever and non-typhoidal salmonellosis, the tick-borne bacterial zoonoses, and non-tuberculosis mycobaterial infections; and arboviral infections. Thus, the overall burden of Africa's NTDs may be severely underestimated. A full assessment is an important step for disease control priorities, particularly in Nigeria and the Democratic Republic of Congo, where the greatest number of NTDs may occur.

Successful treatment of bacterial infection hinders development of acquired immunity

Antibiotics are routinely used to control bacterial infection, but the acquisition of acquired immunity following successful treatment has rarely been examined. We developed a model that allows visualization of acquired immunity during and following antibiotic treatment of typhoid. Pathogen-specific humoral and cellular immune responses were activated rapidly in antibiotic-treated mice, but were not sustained after successful antibiotic treatment and did not confer protection to secondary infection. In marked contrast, pathogen-specific Th1 and Ab responses matured over several weeks following immunization with a live vaccine strain. The deficiency in protective immunity following antibiotic treatment could be overcome by administering flagellin during antibiotic therapy. Thus, development of protective immunity is hindered by rapid therapeutic elimination of bacteria, but can be overcome by providing additional inflammatory and/or antigenic stimuli.

Typhoid sigmoid colon perforation in an 18-month-old boy

BACKGROUND

Typhoid fever is a severe infective disease endemic in the areas where sanitation is poor. Its serious complication is bowel perforation with terminal ileum as the commonest perforation site. We report a case of an extremely unusual site of perforation in sigmoid colon due to typhoid fever.

METHODS

An 18-month-old boy presented with no passage of flatus and feces along with guarding and rigidity. Exploratory laparotomy revealed sigmoid colon perforation and Widal test was strongly positive for typhoid fever. Sigmoid loop colostomy was performed on the patient.

RESULTS

Postoperative period was uneventful. Colostomy started functioning on the 4th post-operative day. There was superficial wound dehiscence. The patient was given oral food intake on the 7th post-operative day. He was discharged from the hospital in satisfactory conditions on the 10th day after operation.

CONCLUSIONS

While tackling a case of enteric perforation suspected with typhoid fever, one should keep in mind the extremely rare site of sigmoid colon perforation.

Chronic Salmonella enterica serovar Typhimurium-induced colitis and cholangitis in streptomycin-pretreated Nramp1+/+ mice

Salmonella enterica subspecies 1 serovar Typhimurium is an enteric bacterial pathogen infecting a broad range of hosts. In susceptible Nramp1(-/-) (Slc11alpha1(-/-)) mice, serovar Typhimurium cannot efficiently colonize the intestine but causes a systemic typhoid-like infection. However, after pretreatment with streptomycin, these susceptible (C57BL/6 and BALB/c) mice develop acute serovar Typhimurium-induced colitis (M. Barthel et al., Infect. Immun. 71:2839-2858, 2003). It was not clear whether resistant Nramp1(+/+) (Slc11alpha1(+/+)) mouse strains would similarly develop colitis. Here we compared serovar Typhimurium infection in streptomycin-pretreated susceptible (C57BL/6) and resistant (DBA/2 and 129Sv/Ev) mouse strains: We found that acute colitis (days 1 and 3 postinfection) is strikingly similar in susceptible and resistant mice. In 129Sv/Ev mice we followed the serovar Typhimurium infection for as long as 6 weeks. After the initial phase of acute colitis, these animals developed chronic crypt-destructive colitis, including ulceration, crypt abscesses, pronounced mucosal and submucosal infiltrates, overshooting regeneration of the epithelium, and crypt branching. Moreover, we observed inflammation of the gall duct epithelium (cholangitis) in the 129Sv/Ev mice between days 14 and 43 of infection. Cholangitis was not attributable to side effects of the streptomycin treatment. Furthermore, chronic infection of 129Sv/Ev mice in a typhoid fever model did not lead to cholangitis. We propose that streptomycin-pretreated 129Sv/Ev mice provide a robust murine model for chronic enteric salmonellosis including complications such as cholangitis.

Carriage of bacteria by proboscises, legs, and feces of two species of flies in street food vending sites in Ouagadougou, Burkina Faso

Flies are widely recognized as potential reservoirs and vectors of bacteria. In the present study, an attempt was made to assess meat-poultry and local fruit juice processing and vending sites for their hygienic status and the presence of houseflies, Musca domestica, and blow flies, Lucilia caesar, for bacterial carriage. The hygienic status results revealed the presence of waste and sewage nearby which provided food and harborage for flies. On the two sites, the M. domestica population was dominant ranging from 76.48 to 91.30%, while the L. caesar population rate ranged from 8.70 to 23.52%. Using specific growth media for bacteria and biochemical tests, bacterial carriage of pooled fly proboscises, legs, and feces were assessed. For both flies, 66.67 to 100% of feces pools were positive for Shigella, Salmonella, and streptococci, while 35.41 to 82.05% of leg and proboscis pools were positive for the same bacteria. In assessment, 0 to 2.56% of feces pools and 8.33 to 28.20% of leg and proboscis pools were staphylococci positive. Coliforms were detected in 100% of pooled organs, while 10 x 10(3) to 1.1 x 10(3) CFU with predominance of coliforms, streptococci, and Shigella were counted on legs and feces of houseflies captured on the two vending sites. Blow flies from the same vending site had an organ bacterial load in the range of 3 x 10(2) to 2.7 x 10(3) CFU per organ. Coliforms, Shigella, and streptococci were present in high numbers. Staphylococci was noticed in low numbers in all parts tested of both flies. Captured housefly and blow fly bacteria-releasing frequency through feces was estimated at 5 to 35 CFU per feces sample for Salmonella and 85 to 495 CFU per feces sample for Shigella.

Multiple-locus variable number tandem repeats analysis for genetic fingerprinting of pathogenic bacteria

DNA fingerprinting has attracted considerable interest as means for identifying, tracing and preventing the dissemination of infectious agents. Various methods have been developed for typing of pathogenic bacteria, which differ in discriminative power, reproducibility and ease of interpretation. During recent years a typing method, which uses the information provided by whole genome sequencing of bacterial species, has gained increased attention. Short sequence repeat (SSR) motifs are known to undergo frequent variation in the number of repeated units through cellular mechanisms most commonly active during chromosome replication. A class of SSRs, named variable number of tandem repeats (VNTRs), has proven to be a suitable target for assessing genetic polymorphisms within bacterial species. This review attempts to give an overview of bacterial agents where VNTR-based typing, or multiple-locus variant-repeat analysis (MLVA) has been developed for typing purposes, together with addressing advantages and drawbacks associated with the use of tandem repeated DNA motifs as targets for bacterial typing and identification.

Risk of travel-associated typhoid and paratyphoid fevers in various regions

BACKGROUND

Although enteric fever (typhoid and paratyphoid fevers) is a major global public health problem, comparable data on the risks of contracting travel-associated enteric fever in various regions of the world are scarce.

METHODS

From the Swedish database on notifiable communicable diseases, we retrieved all case records from 1997 to 2003 on typhoid and paratyphoid fevers. The data set was compared with data on travel patterns obtained from a comprehensive travel database with information from interviews with more than 16,000 Swedish residents with recent overnight travel outside Sweden.

RESULTS

The overall risk of being notified with enteric fever after travel was 0.42 in 100,000 travelers. The highest risk for typhoid fever was seen in travelers from India and neighboring countries (41.7 in 100,000), the Middle East (5.91 in 100,000), and Central Africa (3.33 in 100,000), whereas the risk was comparatively low in East Asia (0.24 in 100,000). Almost the same risk areas stood out for paratyphoid fever: India and neighbors (37.5 in 100,000), the Middle East (3.64 in 100,000), and East Africa (3.33 in 100,000). The epidemiology of paratyphoid fever was considerably affected by a large outbreak of paratyphoid B in a Turkish tourist resort in 1999. The youngest children were at highest risk for typhoid fever (odds ratio 44.2), whereas youths ages 7 to 18 years were at highest risk for paratyphoid fever (odds ratio 9.7).

CONCLUSIONS

Detailed risk data for enteric fever after travel could form the basis for travel advice. Vaccination against typhoid fever should always be considered for travelers to the Indian subcontinent, the Middle East, and Africa but should not routinely be given to travelers to the Malay Peninsula.

Is operative management effective in treatment of perforated typhoid?

BACKGROUND

Salmonella typhi infection continues to be a significant problem worldwide. Patients suffering from "typhoid" in endemic regions such as West Africa often present late in the course of the disease with symptoms of malnutrition and peritonitis. Clinical peritonitis in these patients is invariably associated with perforation of the terminal ileum and purulent peritonitis. Operative intervention and its success have not been well documented. The purpose of this article is to review the experience of 1 hospital in West Africa and the efficacy of operative management of perforated intestine from typhoid.

METHODS

A retrospective review of all patients admitted between January and October of 2003 to the Carolyn Kempton Memorial Hospital in Togo, West Africa, with the diagnosis of typhoid. Demographic data including age, sex, number of perforations, and outcome were obtained. All patients were treated with ampicillin, gentamycin, and flagyl or chloramphenicol as the sole antibiotic therapy along with operative management.

RESULTS

One hundred ninety-one patients with typhoid were admitted. One hundred twelve patients underwent laparotomy for perforation, 18 of whom died from persistent typhoid septicemia for a mortality rate of 16%. Reoperative management was used in some patients who did not respond immediately.

CONCLUSIONS

Primary repair of typhoid perforation is a safe and effective treatment. Patients with persistent septicemia after laparotomy most likely have resistant Salmonella typhi infection. Availability of second-line antibiotic therapy in these third world countries would likely improve outcomes. Prospective studies on appropriate antibiotic therapy along with operative management in endemic areas are necessary until resources are available for preventative measures.

Could flies explain the elusive epidemiology of campylobacteriosis?

Background

Unlike salmonellosis with well-known routes of transmission, the epidemiology of campylobacteriosis is still largely unclear. Known risk factors such as ingestion of contaminated food and water, direct contact with infected animals and outdoor swimming could at most only explain half the recorded cases.

Discussion

We put forward the hypothesis that flies play a more important role in the transmission of the bacteria, than has previously been recognized. Factors supporting this hypothesis are: 1) the low infective dose of Campylobacter; 2) the ability of flies to function as mechanical vectors; 3) a ubiquitous presence of the bacteria in the environment; 4) a seasonality of the disease with summer peaks in temperate regions and a more evenly distribution over the year in the tropics; 5) an age pattern for campylobacteriosis in western travellers to the tropics suggesting other routes of transmission than food or water; and finally 6) very few family clusters.

Summary

All the evidence in favour of the fly hypothesis is circumstantial and there may be alternative explanations to each of the findings supporting the hypothesis. However, in the absence of alternative explanations that could give better clues to the evasive epidemiology of Campylobacter infection, we believe it would be unwise to rule out flies as important mechanical vectors also of this disease.