Displaying publications 1 - 20 of 124 in total

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  1. Usefulness of the Widal test in diagnosing childhood typhoid fever in endemic areas
    Choo KE, Razif AR, Oppenheimer SJ, Ariffin WA, Lau J, Abraham T
    J Paediatr Child Health, 1993 Feb;29(1):36-9.
    PMID: 8461177
    Data are presented for 2382 children investigated for fever in a Malaysian hospital between 1984 and 1987 when Widal tests and blood cultures were a routine part of every fever screen. There were 145 children who were culture positive (TYP-CP) for Salmonella typhi, while 166 were culture negative but were diagnosed as having typhoid (TYP-CN). Analyses of the sensitivity and specificity of combinations of initial Widal titres in predicting a positive S. typhi culture in a febrile child (culture positive vs the rest) showed the best model to be an O- and/or H-titre of > or = 1 in 40 (sensitivity 89%; specificity 89%). While the negative predictive value of the model was high (99.2%) the positive predictive value remained below 50% even for very high titres of O and H (> 1 in 640), at which point the specificity was 98.5%, supporting the clinical view that a high proportion of the TYP-CN patients really were typhoid but were missed by culture. The TYP-CN patients showed a very similar clinical and age profile to TYP-CP patients. The length of history of fever did not affect the initial Widal titre in culture positive cases. The Widal test in children remains a sensitive and specific 'fever screen' for typhoid although it will not identify all cases. In children, lower cut-off points for O- and H-titres should be used than are generally recommended.
    Matched MeSH terms: Typhoid Fever/blood; Typhoid Fever/diagnosis*; Typhoid Fever/immunology; Typhoid Fever/microbiology; Typhoid Fever/epidemiology
  2. Criteria for confirming typhoid fever
    Ross I, Abraham T
    Med J Malaysia, 1986 Mar;41(1):51-2.
    PMID: 3796350
    Matched MeSH terms: Typhoid Fever/diagnosis*
  3. Predicting enteric fever without bacteriological culture results
    Ross IN, Abraham T
    Trans R Soc Trop Med Hyg, 1987;81(3):374-7.
    PMID: 3686631
    We used Bayes' theorem to calculate the probability of enteric fever in 260 patients presenting with undiagnosed fever, without recourse to blood or stool culture results. These individuals were divided into 110 patients with enteric fever (63 culture positive, 47 culture negative) and 150 patients with other causes of fever. Comparison of the frequencies of occurrence of 19 clinical and laboratory events, said to be helpful in the diagnosis of enteric fever, in the two groups revealed that only 8 events were significantly more frequent in enteric fever. These were: a positive Widal test at a screening dilution of 1:40; a peak temperature greater than = 39 degrees C; previous treatment for the fever; a white blood cell count less than 9 X 10(6)/litre; a polymorphonuclear leucocyte count less than 3.5 X 10(6)/litre; splenomegaly; fever duration greater than 7 d; and hepatomegaly. When the probability of enteric fever was determined prospectively in 110 patients, using only 6 of these discriminating events, the probability of patients with a positive prediction having enteric fever (diagnostic specificity) was 0.80 (95% confidence interval: 0.68 to 0.91) and the probability of those with a negative prediction not having enteric fever (diagnostic sensitivity) was 0.92 (0.85 to 0.99). Using all 19 events did not alter the diagnostic specificity or diagnostic sensitivity. This study shows that a small number of clinical and laboratory features can objectively discriminate enteric fever from other causes of fever in the majority of patients. Calculating the probability of enteric fever can aid in diagnosis, when culturing for salmonella is either unavailable or is negative.
    Matched MeSH terms: Typhoid Fever/diagnosis*
  4. Spectrum of flood-related diseases encountered during flood disaster in Johore, Malaysia
    Badrul Hisham, A.S., Nor Azian Shaharom, C.M.D., Marzukhi, M.I., Norli, R., Fatimah, O., Kee, KF, et al.
    Malaysian Journal of Community Health, 2009;15(3):15-23.
    MyJurnal
    The state of Johore, Malaysia had been hit by the worst flood in the Malaysian modern history on the 19th December 2006 (first wave) and the 12th January 2007 (second wave) affecting all the eight districts. A total number of 157,018 and 155,368 Johore population had been displaced by the first and the second wave event respectively. The Johore State Health Department activated the Flood Action Plan which include mobilising medical teams to conduct daily clinical examinations on the flood victims and health teams to inspect flood relief centres, food premises and homes at flood-hit areas with regard to prevent and control communicable diseases. The spreadsheet format was used to collect data on diseases, injury and death throughout the Johore flood disaster period starting from the 19th December 2006 until 19th February 2007. Analyses showed that 19,670 flood victims (36.3%) had communicable diseases and 34,530 (67.0%) had non-communicable diseases. As for the communicable diseases and symptoms/syndromes related to communicable disease, 41.3% were acute respiratory infections (ARI) followed by 25.9% skin infections, 19.1% fever, 10.1% acute gastroenteritis (AGE) and 3.0% acute conjunctivitis. Other infectious diseases include 61 notifiable diseases (46 food poisoning, 14 dengue fever and one tuberculosis), 20 leptospirosis (with two deaths), 20 chicken pox and two melioidosis cases. The Batu Pahat district had the highest incidence for the majority of the communicable diseases because of the prolonged flooding period. No cholera, typhoid, malaria, measles or hand-foot-mouth disease (HFMD) cases were detected among the Johore flood victims. Trends of disease incidence follow the number of evacuees placed in the relief centres corresponding to respective wave. A total of 507 flood victims had physical injuries related to flood mostly due to fall onto wet floor at the relief centres. Fifteen deaths due to drowning were mainly caused by accidental fall into the flood water. The incidence of communicable diseases encountered had been appropriately anticipated and managed attributed to enhanced public health control programmes augmented by syndromic and laboratory surveillance on potentialy fatal infectious diseases. Equal emphasis should be given to the surveillance and control of chronic diseases.
    Matched MeSH terms: Typhoid Fever
  5. Fulltext Genome sequencing and analysis of Salmonella enterica serovar Typhi strain CR0063 representing a carrier individual during an outbreak of typhoid fever in Kelantan, Malaysia
    Baddam R, Kumar N, Shaik S, Suma T, Ngoi ST, Thong KL, et al.
    Gut Pathog, 2012;4(1):20.
    PMID: 23234298 DOI: 10.1186/1757-4749-4-20
    Salmonella Typhi is a human restricted pathogen with a significant number of individuals as asymptomatic carriers of the bacterium. Salmonella infection can be effectively controlled if a reliable method for identification of these carriers is developed. In this context, the availability of whole genomes of carrier strains through high- throughput sequencing and further downstream analysis by comparative genomics approaches is very promising. Herein we describe the genome sequence of a Salmonella Typhi isolate representing an asymptomatic carrier individual during a prolonged outbreak of typhoid fever in Kelantan, Malaysia. Putative genomic coordinates relevant in pathogenesis and persistence of this carrier strain are identified and discussed.
    Matched MeSH terms: Typhoid Fever
  6. Fulltext Genetic fine structure of a Salmonella enterica serovar Typhi strain associated with the 2005 outbreak of typhoid fever in Kelantan, Malaysia
    Baddam R, Kumar N, Thong KL, Ngoi ST, Teh CS, Yap KP, et al.
    J Bacteriol, 2012 Jul;194(13):3565-6.
    PMID: 22689247 DOI: 10.1128/JB.00581-12
    Among enteric pathogens, Salmonella enterica serovar Typhi is responsible for the largest number of food-borne outbreaks and fatalities. The ability of the pathogen to cause systemic infection for extended durations leads to a high cost of disease control. Chronic carriers play important roles in the evolution of Salmonella Typhi; therefore, identification and in-depth characterization of isolates from clinical cases and carriers, especially those from zones of endemicity where the pathogen has not been extensively studied, are necessary. Here, we describe the genome sequence of the highly virulent Salmonella Typhi strain BL196/05 isolated during the outbreak of typhoid in Kelantan, Malaysia, in 2005. The whole-genome sequence and comparative genomics of this strain should enable us to understand the virulence mechanisms and evolutionary dynamics of this pathogen in Malaysia and elsewhere.
    Matched MeSH terms: Typhoid Fever/microbiology; Typhoid Fever/epidemiology
  7. Extensively drug-resistant typhoid fever in Pakistan
    Rasheed MK, Hasan SS, Babar ZU, Ahmed SI
    Lancet Infect Dis, 2019 03;19(3):242-243.
    PMID: 30833059 DOI: 10.1016/S1473-3099(19)30051-9
    Matched MeSH terms: Typhoid Fever/epidemiology*
  8. Analysis and construction of pathogenicity island regulatory pathways in Salmonella enterica serovar Typhi
    Ong SY, Ng FL, Badai SS, Yuryev A, Alam M
    J Integr Bioinform, 2010;7(1).
    PMID: 20861532 DOI: 10.2390/biecoll-jib-2010-145
    Signal transduction through protein-protein interactions and protein modifications are the main mechanisms controlling many biological processes. Here we described the implementation of MedScan information extraction technology and Pathway Studio software (Ariadne Genomics Inc.) to create a Salmonella specific molecular interaction database. Using the database, we have constructed several signal transduction pathways in Salmonella enterica serovar Typhi which causes Typhoid Fever, a major health threat especially in developing countries. S. Typhi has several pathogenicity islands that control rapid switching between different phenotypes including adhesion and colonization, invasion, intracellular survival, proliferation, and biofilm formation in response to environmental changes. Understanding of the detailed mechanism for S. Typhi survival in host cells is necessary for development of efficient detection and treatment of this pathogen. The constructed pathways were validated using publically available gene expression microarray data for Salmonella.
    Matched MeSH terms: Typhoid Fever/genetics
  9. Ribotyping of Salmonella enterica serovar Typhi isolates from Papua New Guinea over the period 1977 to 1996
    Combs BG, Passey M, Michael A, Pang T, Lightfoot D, Alpers MP
    P N G Med J, 2005 Sep-Dec;48(3-4):158-67.
    PMID: 17212062
    The prevalence of typhoid in the Papua New Guinea (PNG) highlands region increased rapidly in the mid-1980s, and now remains endemic. In this study ribotyping has been used to examine the number and types of Salmonella enterica serovar Typhi strains present during the 1977-1996 period. The ribotyping banding pattern results were based on Cla I and Eco RV digests. The 57 PNG isolates were divided into 11 different ribotypes. Comparison of ribotypes using coefficient of similarity values revealed a diverse group of ribotypes. Several strains appear to be endemic in PNG For instance, ribotypes 1, 2 and 3 were most commonly found among PNG isolates and isolates with these ribotypes have been cultured over a period of at least 11 years (1985-1996). Ribotype 3 was also observed in isolates from Malaysia and Thailand. Also found in PNG were ribotypes 4, 5, 6, 7, 8, 9, 16 and 17. The ribotyping suggests that serovar Typhi strains present in PNG include unique strains of serovar Typhi and also strains that are common to other countries.
    Matched MeSH terms: Typhoid Fever/microbiology; Typhoid Fever/epidemiology*
  10. Fulltext Food poisoning outbreak in UiTM, Dungun, Terengganu, 1999.
    Faizan, G., Balkis, A.K., Kasemani, E., Che Mohd Shabri, A., Amirullah, M.A.
    Malaysian Journal of Public Health Medicine, 2002;2(1):50-53.
    MyJurnal
    Food poisoning is still a major problem in the state of Terengganu. The study was conducted during an episode of food poisoning outbreak which occurred in October, 1999, at Universiti Tekonologi Mara (UiTJ1rO, Dungun to determine the etiology, mode of transmission, source and the risk factors of the outbreak and hence to take appropriate remedial actions and preventive measures. A retrospective cohort study was conducted amongst 925 students using a standard questionnaire as well as environmental investigation and bacterial subtyping. All the samples were Malay females, age ranging jrom /9 — 22 years. It was found that majority ofthe victims (72 %) presented with abdominal cramp, 68.5% headache, 60.0% diarrhea, 55.2% fever, 45.0% nausea, 39.0% muscle
    ache and 3]. 7% vomiting. The epidemic curve suggested of a common source of infection and the most probable food that has been contaminated was taken during lunch hour on October 20'I'1999, Statistical analysis showed that spices jiied chicken and "nasi minyak" were significantly associated with the illness (p < 0. 05). The most likely causative organism was Salmonella spp as supported by the clinical presentation and incubation period of the disease, identdication of contaminated food, bacterial subtyping result and environmental findings. Following the outbreaks, several remedial actions were taken including immediate close—up ofthe canteen for I4 days, treatment for the cases and health examination and typhoid immunization for all food handlers.
    Matched MeSH terms: Typhoid Fever
  11. Fulltext The burden of typhoid fever in Klang Valley, Malaysia, 2011-2015
    Muhammad EN, Abdul Mutalip MH, Hasim MH, Paiwai F, Pan S, Mahmud MAF, et al.
    BMC Infect Dis, 2020 Nov 16;20(1):843.
    PMID: 33198646 DOI: 10.1186/s12879-020-05500-x
    BACKGROUND: Typhoid fever causes global morbidity and mortality and is a significant health burden, particularly in low- and middle-income countries. The direct fecal-oral route is the main transmission mode, but indirect environmental transmission could occur, particularly in urban settings. This study aimed to investigate the burden and trend of typhoid fever, reporting the coverage system between government and private practice and pattern of multidrug-resistant (MDR) typhoid cases in the urban Klang Valley area from 2011 to 2015.

    METHODS: The data from a cross-sectional study retrieved from the e-Notifikasi System, a national reporting system for communicable diseases provided by the Disease Control Division, Ministry of Health Malaysia and secondary data of all the typhoid cases were obtained from the public and private hospitals and laboratories in Klang Valley. Descriptive analysis was performed to examine the sociodemographic characteristics, spatial mapping was conducted to examine trends, and the crude incidence rates of confirmed typhoid cases and percentage of reporting coverage were calculated. Significant differences between MDR and non-MDR Salmonella typhi were determined in the patient's sociodemographic characteristics, which were analyzed using χ2 test. P values typhoid fever cases were reported in Klang Valley; however, only 265 cases were confirmed by culture tests. The crude incidence rates of confirmed cases were between 0.5 to 0.7 but peaked at 1.42 per 100,000 population in 2015. Most typhoid fever cases were observed among men (55.6%), individuals aged 21 to 30 years (27.6%), Malaysians (86.3%) and individuals of Malay ethnicity (52.1%). The reporting coverage of confirmed cases was 78.9% and non-reporting coverage of unconfirmed typhoid cases was 79.5%. The predictive value positive (PVP) was 89.3, and 7.5% were detected as MDR Salmonella typhi. Statistical significance was found in gender, citizenship and ethnicity regarding MDR Salmonella typhi (p = 0.004, p = 0.008 and p = 0.034, respectively).

    CONCLUSIONS: The local transmission of typhoid is still prevalent in the Klang Valley despite rapid urbanization and development in recent years. These findings are essential for policy makers to plan and implement focused and effective preventative activities to curb typhoid infection in urban areas.

    Matched MeSH terms: Typhoid Fever/drug therapy; Typhoid Fever/microbiology; Typhoid Fever/epidemiology*; Typhoid Fever/transmission
  12. Fulltext Genome Sequence of Salmonella enterica subsp. enterica Serovar Typhi Isolate PM016/13 from Untreated Well Water Associated with a Typhoid Outbreak in Pasir Mas, Kelantan, Malaysia
    Muhamad Harish S, Sim KS, Najimudin N, Aziah I
    Genome Announc, 2015;3(6).
    PMID: 26564032 DOI: 10.1128/genomeA.01261-15
    Salmonella enterica subsp. enterica serovar Typhi is a human-restricted pathogen that causes typhoid fever. Even though it is a human-restricted pathogen, the bacterium is also isolated from environments such as groundwater and pond water. Here, we describe the genome sequence of the Salmonella enterica subsp. enterica serovar Typhi PM016/13 which was isolated from well water during a typhoid outbreak in Kelantan, Malaysia, in 2013.
    Matched MeSH terms: Typhoid Fever
  13. Fulltext Complete Genome Sequence of Salmonella enterica subsp. enterica Serovar Typhi Isolate B/SF/13/03/195 Associated with a Typhoid Carrier in Pasir Mas, Kelantan, Malaysia
    Muhamad Harish S, Sim KS, Mohd Nor F, Mat Hussin H, Hamzah WM, Najimudin N, et al.
    Genome Announc, 2015;3(6).
    PMID: 26564035 DOI: 10.1128/genomeA.01285-15
    We report here the complete genome sequence of Salmonella enterica subsp. enterica serovar Typhi B/SF/13/03/195 obtained from a typhoid carrier, who is a food handler in Pasir Mas, Kelantan.
    Matched MeSH terms: Typhoid Fever
  14. Fulltext The worst flood in 100 years : Johore experience
    Marzukhi, M.I., Daud, A.R., Badrul Hisham, A.S.
    Malaysian Journal of Community Health, 2009;15(3):1-14.
    MyJurnal
    Past major flooding events for the state of Johore, Malaysia were recorded in 1926, 1967, 1968 and 1971. However, major meteorological phenomena that hit Johore on the 19th December 2006 (first wave) and the 12th January 2007 (second wave) were claimed to be the worst flood disaster in Johore in a 100 years. All eight districts were affected displacing 157,018 and 155,368 population during the first and the second wave event respectively. The Johore Health Department deployed substantial number of medical and health personnel to deal with the Johore flood crisis. Flood-related data were collected on daily basis between 19th December 2006 and 19th February 2007 using spreadsheet format from Flood Operational Rooms located at respective District Health Offices. Among flood victims 34,530 were found to have non-communicable diseases and 19,670 with communicable diseases. No major food- and water-borne disease outbreaks, such as cholera and typhoid, were reported in Johore. High success of public health measures was depending on the workforce of medical and health personnel on the ground. On the other hand, voluntary services offered by non-governmental organisations (NGOs), private sector and other volunteers should be well coordinated without compromising regulatory and ethical requirements. Crisis guidelines and plan of actions shall be updated so that they would be more relevant to the crises encountered on the ground.
    Matched MeSH terms: Typhoid Fever
  15. Toll-like receptor 4 Asp299Gly and Thr399Ile polymorphisms and typhoid susceptibility in Asian Malay population in Malaysia
    Bhuvanendran S, Hussin HM, Meran LP, Anthony AA, Zhang L, Burch LH, et al.
    Microbes Infect, 2011 Sep;13(10):844-51.
    PMID: 21612766 DOI: 10.1016/j.micinf.2011.04.007
    Typhoid fever is a major health problem with frequent outbreaks in Kelantan, Malaysia. Prevalence of TLR4 gene polymorphisms varies with ethnic groups (0-20%) and predisposean individual to gram-negative infections. The prevalence rate of TLR4 Asp299Gly and Thr399lle polymorphisms in the Malay population or the influence of these on typhoid fever susceptibility is not yet reported. 250 normal and 304 susceptible Malay individuals were investigated for these polymorphisms using allele-specific PCR and analysed for its association with typhoid fever susceptibility. The total prevalence of polymorphisms in the normal population was 4.8% in comparison to 12.5% in the susceptible population (p = 0.002). An increased frequency of both polymorphisms was observed in the susceptible population (p typhoid fever in Kelantan could be attributed to the higher percentage of Malays (95%) in this state. In order to reduce the incidence of this disease, people with these polymorphisms, can be prioritised for prophylactic strategies.
    Matched MeSH terms: Typhoid Fever/genetics*; Typhoid Fever/immunology
  16. "Preliminary report of the beneficial effect of chloromycetin in the treatment of typhoid fever"--a commentary
    Basnyat B
    Wilderness Environ Med, 2004;15(3):216-7.
    PMID: 16331874
    Matched MeSH terms: Typhoid Fever/drug therapy; Typhoid Fever/history*
  17. Serum C-reactive protein concentrations in Malaysian children with enteric fever
    Choo KE, Davis TM, Henry RL, Chan LP
    J Trop Pediatr, 2001 Aug;47(4):211-4.
    PMID: 11523761
    To investigate the role of serum C-reactive protein (CRP) in the diagnosis of typhoid fever, we studied 227 febrile Malaysian children hospitalized during a 12-month period. The children were: culture-positive for Salmonella typhi (Group 1; n = 108); culture-negative but with typical clinical features of typhoid fever (Group 2; n = 60); or had non-typhoidal illness (Group 3; n = 59). Group 1 children had the highest serum CRP concentrations (geometric mean [SD range]; 43 [12-150] mg/l vs. 26 [8-85] mg/l in Group 2 and 21 [4-110] mg/l in Group 3; p < 0.001). In regression analysis, age, patient group and fever duration were independently associated with serum CRP (p < 0.05) but gender was not. In Group 1 patients, there was a significant positive association between serum CRP and Widal O and H agglutinin titres. In receiver-operator characteristic (ROC) analysis of serum CRP for Groups 1 and 2 combined, compared with Group 3, the area under the curve (AUC) was 0.65. These data show that the serum CRP is highest in culture-positive children with enteric fever and reflects the immune response to the infection in this group. Nevertheless, serum CRP had relatively low sensitivity and specificity for confirmed or clinically diagnosed typhoid fever (68 and 58 per cent, respectively at 'cut-off' concentration 30.0 mg/l), and an AUC value only moderately above that associated with no predictive power (0.5). Although of limited use as a primary diagnostic test, a raised serum CRP may still have a place as one of a range of features that facilitate assessment of a febrile child in a typhoid-endemic area.
    Matched MeSH terms: Typhoid Fever/blood*; Typhoid Fever/diagnosis
  18. Trends in the antibiotic resistance patterns of enteric Fever isolates - a three year report from a tertiary care centre
    Gupta V, Singla N, Bansal N, Kaistha N, Chander J
    Malays J Med Sci, 2013 Jul;20(4):71-5.
    PMID: 24043999
    BACKGROUND: The incidence of multidrug resistant enteric fever is increasing alarmingly. This study was planned to determine the rate of isolation of Salmonella spp. and to compare the isolates for their epidemiological parameters and antimicrobial susceptibility patterns at our center.

    METHODS: The study was conducted over a span of three years with a total of 8142, 8134, and 8114 blood culture samples processed for the years 2008, 2009, and 2010 respectively. The minimum inhibitory concentration (MIC) for ciprofloxacin and chloramphenicol was determined using an agar dilution method. The MIC for ciprofloxacin was also confirmed by Epsilon-test (E -test) strips.

    RESULTS: Of the total 302 Salmonella spp. isolated, 257 were Salmonella enterica serotype Typhi (85.1%) and 45 (14.9%) were S. enterica serotype Paratyphi A. The majority of the isolates recovered were from the pediatric age group (54.6%) and males (60.6%). Complete susceptibility was observed to chloramphenicol, cefotaxime, ceftriaxone, and azithromycin over the last two years (2009 and 2010), with an increase in resistance to nalidixic acid (100%) and ciprofloxacin (13.6%).

    CONCLUSION: In our study, we found augmentation of resistance to nalidixic acid and fluoroquinolones and complete sensitivity to ceftriaxone along with reemergence of chloramphenicol sensitivity for Salmonella isolates. This report emphasises the necessity of continuous surveillance of antibiograms of enteric fever isolates in an area.

    Matched MeSH terms: Typhoid Fever
  19. Fulltext An outbreak of typhoid from a wedding party in Bachok district, Kelantan, 2003
    Wan Mansor, W.H., Hamizah, M.S., Wan Sulaili, W.S., Jeriah, I., Che Nok @ Nawi, I., Noraini, I., et al.
    Malaysian Journal of Public Health Medicine, 2003;3(2):53-57.
    MyJurnal
    On March 17, 2003 the Kelantan Health Department was notihed about a possible typhoid outbreak following a wedding party. An investigation was carried out to identiy the source and recommend control measures. Active case detection, yield investigation and case»control study were conducted. Cases were symptomatic attendees with a stool or blood culture positive for Salmonella
    typhii. Each control had a negative culture and denied symptoms. Of the more than 1 OOO guests, 477 experienced fever; 152 met the case definition. The party hostess was found to be an Salmonelb typhii carrier. Syrup prepared with untreated well water was identified as the most likely source for this outbreak, with an odds ratio 14.0 (95% C1: 2.9, 104.1). This was a common source
    outbreak of typhoid. We recommend that all food handlers at large parties be screened for typhoid and other foodborne diseases and samples of higherisk foods should be kept for few days after each event in case they are needed for testing.
    Matched MeSH terms: Typhoid Fever
  20. Fulltext Crystal structure of an antigenic outer-membrane protein from Salmonella Typhi suggests a potential antigenic loop and an efflux mechanism
    Guan HH, Yoshimura M, Chuankhayan P, Lin CC, Chen NC, Yang MC, et al.
    Sci Rep, 2015 Nov 13;5:16441.
    PMID: 26563565 DOI: 10.1038/srep16441
    ST50, an outer-membrane component of the multi-drug efflux system from Salmonella enterica serovar Typhi, is an obligatory diagnostic antigen for typhoid fever. ST50 is an excellent and unique diagnostic antigen with 95% specificity and 90% sensitivity and is used in the commercial diagnosis test kit (TYPHIDOT(TM)). The crystal structure of ST50 at a resolution of 2.98 Å reveals a trimer that forms an α-helical tunnel and a β-barrel transmembrane channel traversing the periplasmic space and outer membrane. Structural investigations suggest significant conformational variations in the extracellular loop regions, especially extracellular loop 2. This is the location of the most plausible antibody-binding domain that could be used to target the design of new antigenic epitopes for the development of better diagnostics or drugs for the treatment of typhoid fever. A molecule of the detergent n-octyl-β-D-glucoside is observed in the D-cage, which comprises three sets of Asp361 and Asp371 residues at the periplasmic entrance. These structural insights suggest a possible substrate transport mechanism in which the substrate first binds at the periplasmic entrance of ST50 and subsequently, via iris-like structural movements to open the periplasmic end, penetrates the periplasmic domain for efflux pumping of molecules, including poisonous metabolites or xenobiotics, for excretion outside the pathogen.
    Matched MeSH terms: Typhoid Fever/diagnosis; Typhoid Fever/microbiology*
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