Objective: To understand the epidemiological and molecular characteristics of typhoid and paratyphoid in China from 2009 to 2013, and provide evidence for the prevention and control of typhoid and paratyphoid, the development and improvement of surveillance strategies. Methods: Epidemiological analysis was conducted on the incidence data of typhoid and paratyphoid, and related public health emergencies in China during 2009-2013. Pathogen isolation and culture, serologic test were conducted for the typhoid and paratyphoid cases from 13 national surveillance sites. The isolates were subjected to antimicrobial susceptibility testing. Pulsed-field gel electrophoresis (PFGE) was performed for the molecular typing of these isolates. Results: The average incidence of typhoid and paratyphoid in China during this period was 1.03/100 000. The reported case number and incidence decreased with year. The provinces reporting high case numbers were Yunnan, Guizhou, Guangxi, Hunan, Zhejiang, Guangdong and Xinjiang. The incidence of age group 0-4 years was highest. The proportion of farmers and children outside child care settings showed an increasing tendency over time. The annual incidence peak was during July-August. Twenty five outbreaks occurred during 2009-2013. The results of pathogen isolation and culture showed that the positive rate was 3.00% (940/31 322), among the positive isolates, the proportion of Salmonella paratyphi A accounted for higher proportion (68.19%, 641/940) compared with Salmonella typhi (31.60%, 297/940). The drug resistances of Salmonella typhi and Salmonella paratyphi varied, but their resistances to nalidixic acid were highest (50.22% and 85.33%) respectively. A certain amount of Salmonella typhi isolates showed the resistance to the 3rd generation cephalosporins. PFGE analysis showed divergent patterns of Salmonella typhi compared with limited patterns of Salmonella paratyphi A. Conclusion: The epidemic level of typhoid and paratyphoid in China was relatively low, but the outbreak occurred occasionally. It is necessary to enhance the laboratory-based surveillance, particularly the capability of etiological diagnosis, outbreak investigation, response and antibiotic resistance monitoring, and conduct risk factor investigation in provinces with high incidences in recent years.
Child ; Child, Preschool ; China/epidemiology* ; Disease Outbreaks ; Drug Resistance, Bacterial/genetics* ; Electrophoresis, Gel, Pulsed-Field ; Epidemics ; Farmers ; Humans ; Incidence ; Infant ; Molecular Typing ; Paratyphoid Fever/microbiology* ; Population Surveillance ; Salmonella paratyphi A/isolation & purification* ; Salmonella typhi/isolation & purification* ; Typhoid Fever/microbiology*

INTRODUCTIONEnteric fever is a multisystemic infection which largely affects children. This study aimed to analyse the epidemiology, clinical presentation, treatment and outcome of paediatric enteric fever in Singapore.

MATERIALS AND METHODSA retrospective review of children diagnosed with enteric fever in a tertiary paediatric hospital in Singapore was conducted from January 2006 to January 2012. Patients with positive blood cultures for Salmonella typhi or paratyphi were identified from the microbiology laboratory information system. Data was extracted from their case records.

RESULTSOf 50 enteric fever cases, 86% were due to Salmonella typhi, with 16.3% being multidrug resistant (MDR) strains. Sixty-two percent of S. typhi isolates were of decreased ciprofloxacin susceptibility (DCS). Five cases were both MDR and DCS. The remaining 14% were Salmonella paratyphi A. There were only 3 indigenous cases. Ninety-four percent had travelled to typhoid-endemic countries, 70.2% to the Indian subcontinent and the rest to Indonesia and Malaysia. All patients infected with MDR strains had travelled to the Indian subcontinent. Anaemia was a significant finding in children with typhoid, as compared to paratyphoid fever (P = 0.04). Although all children were previously well, 14% suffered severe complications including shock, pericardial effusion and enterocolitis. None had typhoid vaccination prior to their travel to developing countries.

CONCLUSIONEnteric fever is largely an imported disease in Singapore and has contributed to significant morbidity in children. The use of typhoid vaccine, as well as education on food and water hygiene to children travelling to developing countries, needs to be emphasised.

Adolescent ; Anemia ; epidemiology ; Anti-Bacterial Agents ; therapeutic use ; Child ; Child, Preschool ; Drinking Water ; Drug Resistance, Multiple, Bacterial ; physiology ; Enterocolitis ; epidemiology ; Female ; Food Contamination ; Health Education ; Hospitals, Pediatric ; Humans ; India ; Indonesia ; Infant ; Malaysia ; Male ; Paratyphoid Fever ; drug therapy ; epidemiology ; microbiology ; Pericardial Effusion ; epidemiology ; Retrospective Studies ; Salmonella paratyphi A ; physiology ; Salmonella typhi ; physiology ; Shock ; epidemiology ; Singapore ; epidemiology ; Tertiary Care Centers ; Travel ; Typhoid Fever ; drug therapy ; epidemiology ; microbiology ; prevention & control ; Typhoid-Paratyphoid Vaccines ; therapeutic use

A 48-year-old woman was presented to our clinic with some fever and neck pains for about one month. Based on the symptoms and results of image, an empirical diagnosis of tuberculous cervical spondylitis was made. The pain was not significantly decreased after anti-tuberculosis therapy. And, 3 weeks later, she was re-admitted to our hospital for the unbearable pain. An exploration of the C4/5 by the anterior medial approach was recommended to evaluate the germ and debridement. Bacteriological tests showed that the pathogen was Salmonella Enteritidis. The pain was relieved significantly after operation and sensitive antibiotic treatments. Infections with Salmonella Typhi or Salmonella Paratyphi have been well-documented, while there are few reports of cervical spondylitis caused by Salmonella Enteritidis. We reported a case of a healthy woman with whom pyogenic cervical spondylitis of Salmonella Enteritidis was corroborated and treated and reviewed according to previous reports about spondylitis caused by Salmonella Enteritidis in the literature.
Cervical Vertebrae ; Debridement ; Diagnosis ; Female ; Fever ; Humans ; Middle Aged ; Neck Pain ; Salmonella enteritidis* ; Salmonella paratyphi A ; Salmonella typhi ; Salmonella* ; Spondylitis*

OBJECTIVETo determine the distribution and sequence conservation of pagC gene in Salmonella paratyphi A isolates, and the immunogenicity and immunoprotection of its recombinant expression products (rPagC).

METHODSThe distribution of pagC gene in Salmonella paratyphi A isolates and its sequence conservation were examined by PCR and sequencing. A prokaryotic expression system of pagC gene was constructed and the expressed rPagC was extracted by Ni-NTA affinity chromatography. SDS-PAGE and Bio-Rad Gel Image Analyzer were applied to examine the expression and yield of rPagC. The antigenicity and immunoreactivity of rPagC were detected by immunodiffusion test, ELISA and Western Blot assay. The immunoprotective effect of rPagC against infection of Salmonella paratyphi A in mice was determined, while the agglutinative effect of sera from rPagC-immunized mice was measured by micro-Widal's test.

RESULTSAll the Salmonella paratyphi A isolates tested had the pagC gene, the similarity of nucleotide and amino acid sequences was 99.1 %-100 % and 98.4 %-100 %, respectively. The constructed prokaryotic expression system expressed rPagC with high efficiency. The rPagC immunized rabbit produced a high level antibody and it also combined with antiserum against whole cell of S. paratyphi A to generate a positive Western hybridization signal. ELISA results indicated that 97.1 % (66/68) paratyphoid patients infected with Salmonella paratyphi A were positive for rPagC antibody in their serum specimens. When mice were immunized with 100 μg or 200 μg rPagC, the immunoprotective rates were 73.3 % (11/15) or 86.7 % (13/15), respectively. The sera from rPagC-immunized mice offered 1:10-1:40 agglutination titers with the H antigens of Salmonella paratyphi A and Salmonella typhi.

CONCLUSIONPagC gene has an extensive distribution in Salmonella paratyphi A isolates. rPagC can be used as the candidate antigen in genetic engineering vaccine due to its fine immunogenicity and powerful immunoprotective effect.

Agglutination Tests ; Animals ; Antibodies, Bacterial ; blood ; Antigens, Bacterial ; genetics ; immunology ; Bacterial Proteins ; genetics ; immunology ; Bacterial Vaccines ; Membrane Proteins ; genetics ; immunology ; Mice ; Rabbits ; Recombinant Proteins ; genetics ; immunology ; Salmonella paratyphi A ; genetics ; immunology ; Sequence Homology, Amino Acid ; Sequence Homology, Nucleic Acid

INTRODUCTIONEnteric fever is a common infection in endemic areas; however, there are few reports describing the computed tomography (CT) manifestations of enteric fever. We aim to describe and illustrate CT findings in enteric fever in this study.

MATERIALS AND METHODSA retrospective search of medical records in our institute for patients with positive blood cultures for Salmonella typhi, and Salmonella paratyphi organisms yielded 39 cases. Among these patients, 12 had undergone a CT study of the abdomen. The CT images, laboratory and clinical findings of these 12 patients were reviewed.

RESULTSThe most common clinical presentation was fever (100%). Typical features of gastroenteritis were present in only over half of the patients. Liver function tests were abnormal in all patients. The most common abdominal manifestations on CT were the presence of mesenteric lymphadenopathy and splenomegaly (75%). Other features were circumferential small bowel wall thickening (58.3%) and free intraperitoneal fluid (50%). Three patients were found to have complications; one with bleeding from terminal ileal ulceration, another with an ileal perforation and the third with renal abscess formation.

CONCLUSIONCT is useful in evaluating enteric fever in patients with severe forms of presentation, a longer clinical course or less specific symptoms. Although the imaging features overlap with other abdominal infections, when combined with clinical features, travel history to endemic areas and presence of transaminitis, the diagnosis of enteric fever should be considered. CT in particular, is useful for the detection of complications such as perforation, bleeding and abscess formation.

Abscess ; diagnostic imaging ; Adolescent ; Adult ; Aged ; Ascitic Fluid ; diagnostic imaging ; Child ; Child, Preschool ; Female ; Humans ; Intestine, Small ; diagnostic imaging ; Lymphatic Diseases ; diagnostic imaging ; Male ; Middle Aged ; Paratyphoid Fever ; diagnostic imaging ; Radiography, Abdominal ; Retrospective Studies ; Salmonella paratyphi A ; Salmonella paratyphi B ; Salmonella typhi ; Splenomegaly ; diagnostic imaging ; Tomography, X-Ray Computed ; Typhoid Fever ; diagnostic imaging

OBJECTIVETo analyze molecular and evolution characteristics of Salmonella Paratyphi A isolates from 2000 to 2008, China.

METHODSUsing pulsed-field gel electrophoresis (PFGE) method with SpeI restriction enzyme, and multilocus sequence typing (MLST) method based on housekeeping genes (aroC, thrA, hisD, purE, sucA, dnaN, hemD, adk, and purA), the genomic variations of 118 Salmonella Paratyphi A isolates from 10 regions during 2000 to 2008 were analyzed.

RESULTSUsing PFGE method, 118 Salmonella Paratyphi A isolates were clustered into 32 PFGE patterns, and 5 patterns were predominant (5 isolates or above). However, only 2 MLST types were identified for all isolates with MLST method. Among all Salmonella Paratyphi A isolates, the sequences of housekeeping genes were highly conservative and showed a high degree of cloning.

CONCLUSIONFor Chinese epidemic Salmonella Paratyphi A isolates during 2000 - 2008, MLST method showed low discrimination power and the MLST method should not be applied to outbreak and epidemiological surveillance of Salmonella Paratyphi A. Currently, nationwide paratyphoid fever epidemics is caused by highly clonal isolates in China. As the time changes, these isolates also accumulate sporadic mutations.

Bacterial Typing Techniques ; China ; DNA, Bacterial ; genetics ; Electrophoresis, Gel, Pulsed-Field ; methods ; Humans ; Multilocus Sequence Typing ; Paratyphoid Fever ; epidemiology ; microbiology ; Salmonella paratyphi A ; classification ; genetics ; isolation & purification ; Sequence Analysis, DNA ; Serotyping

OBJECTIVETo study the immunogenicity and immunoprotection of the recombinant expressing product (rSpaO) of S. paratyphi A spaO gene, and to demonstrate the frequencies of spaO gene carrying and expressing in S. paratyphi A isolates.

METHODSThe spaO gene of a clinical S. paratyphi A strain JH01 was amplified and then cloned. After sequencing of the cloned spaO gene, a prokaryotic expression system of the gene was constructed. SDS-PAGE were applied to examine the rSpaO expression. Ni-NTA affinity chromatography was performed to collect rSpaO. Immunogenicity of rSpaO was determined by Western blot assay. A PCR assay and an ELISA were established to respectively detect the carrying and expressing frequencies of the spaO genes in 98 S. paratyphi A isolates. The immunoprotective effects of rSpaO in S. paratyphi A strain 50001 infected mice were observed.

RESULTSIn comparison with the reported corresponding sequences, the nucleotide and putative amino acid sequence homologies of the cloned spaO gene were 99.45%-99.89% and 99.01%-100%, respectively. The expression output of rSpaO was approximately 75% of the total bacterial proteins. S. paratyphi A antiserum could recognize as well as combine with rSpaO. rSpaO could efficiently induce rabbits to produce specific antibody. 94.9% (93/98) of the S. paratyphi A isolates had spaO gene and 91.4% (85/93) of the spaO+ strains could express SpaO. 58.3% and 50.0% of the mice that oral-taken or subcutaneous injected with 500 microg of rSpaO for immunization were survival after challenged by lethal dose of S. paratyphi A strain 50001. When co-immunized with 5 microg rLTB, the survival rates of the mice increased to 88.3% and 75.0%, respectively.

CONCLUSIONThe S. paratyphi isolates had relatively high carrying and expressing frequencies of spaO gene. rSpaO showed a fine immunogenicity and a certain immunoprotective effect, which could be used as an antigen candidate for developing genetic engineering vaccine of S. paratyphi.

Animals ; Antibody Formation ; Bacterial Proteins ; genetics ; immunology ; Cloning, Molecular ; Electrophoresis, Polyacrylamide Gel ; Enzyme-Linked Immunosorbent Assay ; Gene Expression Regulation, Bacterial ; Genetic Engineering ; Membrane Proteins ; genetics ; immunology ; Mice ; Polymerase Chain Reaction ; Recombinant Proteins ; Salmonella Vaccines ; immunology ; Salmonella paratyphi A ; genetics

OBJECTIVETo analyze the molecular types of Salmonella paratyphi A strains isolated in the recent years, and to construct the standard S. paratyphi A databank in the laboratory surveillance network PulseNet China.

METHODSS. paratyphi A isolates from 4 provinces were analyzed with the standard pulsed-field gel electrophoresis (PFGE) protocol used in PulseNet and their patterns compared. The databank was constructed with BioNumerics.

RESULTSEleven PFGE patterns were obtained, in which 3 predominant patterns were identifies with a similarity coefficient of 96.3%. The strains of these patterns, accounted for 86.5% of the analyzed strains, appeared in different provinces and years.

CONCLUSIONThe databank of S. paratyphi A was constructed and could be used in laboratory surveillance of S. paratyphi A in PulseNet China. From the analyses on molecular typing of the isolates, data suggested that the predominant strains might cause the epidemics in different regions.

China ; Electrophoresis, Gel, Pulsed-Field ; Salmonella paratyphi A ; classification ; genetics ; isolation & purification

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Azithromycin ; pharmacology ; Bacteremia ; microbiology ; Child ; Child, Preschool ; Culture Media ; Drug Resistance, Bacterial ; Drug Resistance, Multiple, Bacterial ; Escherichia coli ; drug effects ; isolation & purification ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Methicillin Resistance ; Middle Aged ; Penicillin G ; pharmacology ; Salmonella paratyphi A ; drug effects ; isolation & purification ; Staphylococcus aureus ; drug effects ; isolation & purification ; Staphylococcus epidermidis ; drug effects ; isolation & purification

Salmonellae cause a number of characteristic clinical infections in humans, including gastroenteritis, enteric fever, bacteremia, focal metastatic infection and an asymptomatic chronic carrier state. We report a case of large hepatic cyst infected with Salmonella paratyphi A. A 47-year-old woman was admitted, because of abdominal complains (fullness and pain) and fever. On physical examination, a mass was palpated on right upper quadrant of the abdomen. The computerized tomography of the abdomen showed a large hepatic cyst, but not cystic infection. Aspiration and percutaneous drainage of the hepatic cyst were perfomed for the therapeutic decompression under fluoroscopic guidance. Cultures of the cyst fluid revealed growth of Salmonella paratyphi A. Radiologic contrast media after draining of the cyst fluid revealed no communication between the cyst and bile ducts. Infected hepatic cyst appeared to result from hematogenic seeding. One month later, the patient improved and was discharged without any complication.
Abdomen ; Bacteremia ; Bile Ducts ; Carrier State ; Contrast Media ; Cyst Fluid ; Decompression ; Drainage ; Female ; Fever ; Gastroenteritis ; Humans ; Middle Aged ; Physical Examination ; Salmonella paratyphi A* ; Salmonella* ; Typhoid Fever