Resistome is a cluster of microbial genes encoding proteins with necessary functions to resist the action of antibiotics. Resistome governs essential and separate biological functions to develop resistance against antibiotics. The widespread clinical and nonclinical uses of antibiotics over the years have combined to select antibiotic-resistant determinants and develop resistome in bacteria. At present, the emergence of drug resistance because of resistome is a significant problem faced by clinicians for the treatment of Salmonella infection. Antibiotic resistome is a dynamic and ever-expanding component in Salmonella. The foundation of resistome in Salmonella is laid long before; therefore, the antibiotic resistome of Salmonella is reviewed, discussed, and summarized. We have searched the literature using PubMed, MEDLINE, and Google Scholar with related key terms (resistome, Salmonella, antibiotics, drug resistance) and prepared this review. In this review, we summarize the status of resistance against antibiotics in S. typhi, highlight the seminal work in the resistome of S. typhi and the genes involved in the antibiotic resistance, and discuss the various methods to identify S. typhi resistome for the proactive identification of this infection and quick diagnosis of the disease.
Anti-Bacterial Agents/pharmacology* ; Drug Resistance ; Humans ; Microbial Sensitivity Tests ; Salmonella ; Salmonella typhi/genetics*

Neuroretinitis (NR) is an inflammation of the optic nerve and the neural retina. NR is diagnosed clinically, and it is characterized by blurring of vision (BOV), optic disc swelling, and macular star exudates. Spontaneous resolution of NR is possible, but corticosteroids help in hastening recovery. Rarely, Salmonella typhi infection may produce an immune-mediated reaction that can cause NR. Immune-mediated retinitis occurs 3 to 6 weeks after the febrile period of a typhoid infection. We present the case of a 55-year-old female with a two-week history of painless, unilateral BOV occurring five weeks after the initial febrile episode of a typhoid infection. A diagnosis of NR was made after fundus examination on the affected eye showed optic disc edema and macular star exudates. An eight-week course of corticosteroid treatment afforded partial resolution of the disc edema and significant reduction in the macular exudates, and improved the patient’s vision after six months.
Salmonella typhi ; Tomography, Optical Coherence

Background: Salmonella enterica ser. Typhi and Salmonella enterica ser. Paratyphi are agents of typhoid fever, a severe systemic disease, which remains to be a public health concern in the Philippines. Infection due to non-typhoidal Salmonella (NTS), on the other hand, most often results in a self-limiting acute gastroenteritis but may result in invasive disease in some cases. There is scarcity of information on the Salmonella serotypes in the Philippines which limits understanding of the distribution, transmission and antimicrobial resistance of these bacteria. Objective: This study describes the serotype distribution and antimicrobial resistance of Salmonella in the Philippines over a 15-year period. Methodolgy: Salmonella isolates were collected through the Philippine Department of Health-Antimicrobial Resistance Surveillance Program (DOH-ARSP) from January 1, 2004 to December 31, 2018. The isolates were serotyped using Sven Gard method for slide agglutination using antigens from Denka Seiken (Japan), and S and A serotest (Thailand). Antigenic formula obtained were classified according to White-Kauffmann-LeMinor scheme. Antimicrobial susceptibility testing for ampicillin, ceftriaxone, cefotaxime, chloramphenicol, ciprofloxacin, and trimethoprim-sulfamethoxazole, were performed using both automated and conventional methods (Kirby Bauer disk diffusion and gradient diffusion method). Antimicrobial susceptibility results were interpreted using Clinical and Laboratory Standards Institute (CLSI) 2018 interpretive criteria (M100Ed28E). Results: A total of 2,387 isolates were collected from human specimens during the 15-year study period. There were 69 serotypes of Salmonella identified with the most common being Salmonella enterica ser. Typhi: n=1895 (79.39%), Salmonella enterica ser. Enteritidis: n=182 (7.62%), Salmonella enterica ser. Typhimurium: n=87 (3.64%), Salmonella enterica ser. Weltevreden: n=24 (1.00%), Salmonella enterica ser. Paratyphi A: n=17 (0.71%), Salmonella enterica ser. Stanley: n=17 (0.71%), Salmonella enterica ser. Anatum: n=13 (0.54%), Salmonella enterica ser. Heidelberg: n=12 (0.50%), Salmonella enterica ser. Choleraesuis var. Kunzendorf: n=9 (0.38%). The multidrug resistant Salmonella serotypes reported in this study were mostly resistant to ampicillin, cefotaxime, ciprofloxacin combinations. Conclusion This present study showed that prevailing Salmonella serotypes in the Philippines were similar with Salmonella serotypes reported from other Asian countries. Typhoidal isolates were high among 6-17 years old and were mostly from males. The antimicrobial resistance rates for typhoidal Salmonella isolates to ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, ciprofloxacin, ceftriaxone and cefotaxime were lower compared with the antimicrobial resistance rates for non-typhoidal Salmonella isolates. Multidrug resistance for both Salmonella Typhi and NTS were relatively low. Continued and enhanced surveillance is needed to monitor the rising levels of antimicrobial resistance, determine risk factors and exposures associated with Salmonella Typhi and NTS infection to guide prevention and control measures.
Salmonella typhi ; Drug Resistance, Multiple

Previously, we genetically engineered a Salmonella Typhi bacterial ghost (STG) as a novel inactivated vaccine candidate against typhoid fever. The underlying mechanism employed by the ghost in stimulating the adaptive immune response remains to be investigated. In this study, we aimed to evaluate the immunostimulatory effect of STG on mouse bone marrow-derived dendritic cells (BMDCs) and its activation of the adaptive immune response in vitro. Immature BMDCs were stimulated with STG, which efficiently stimulated maturation events in BMDCs, as indicated by upregulated expressions of CD40, CD80, and major histocompatibility complex class II molecules on CD11⁺ BMDCs. Immature BMDCs responded to STG stimulation by significantly increasing the expression of interleukin (IL)-6, which might indicate the induction of dendritic cell maturation in vivo (p < 0.05). In addition, ghost-stimulated murine BMDCs showed significant expressions of interferon gamma and IL-4, which can drive the development of Th1 and Th2 cells, respectively, in co-cultured CD4⁺ T cells in vitro. These results suggest that STG can effectively stimulate maturation of BMDCs and facilitate subsequent immune responses via potent immunomodulatory cytokine responses.
Adaptive Immunity ; Animals ; Bacteriophages ; Dendritic Cells ; Immunity, Innate ; In Vitro Techniques ; Interferons ; Interleukin-4 ; Interleukins ; Major Histocompatibility Complex ; Mice ; Salmonella typhi ; Salmonella ; T-Lymphocytes ; Th2 Cells ; Typhoid Fever

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

Non-typhoid salmonellosis is an infectious disease caused by Salmonella species other than Salmonella typhi. Although the usual clinical course of non-typhoid salmonellosis is a benign self-limiting gastroenteritis, these bacteria are especially problematic in immunocompromised individuals, including patients with malignancies, human immunodeficiency virus, or diabetes, and those receiving corticosteroids or other immunotherapy agents. In addition to enteric symptoms, Salmonella species give rise to extra-intestinal complications, including self-limiting arthritis, which appears 1 to 3 weeks after the onset of infection and lasts from a few weeks to several months. In some patients, however, this arthritis spears to be chronic in nature. We describe herein a living-donor liver transplant recipient who experienced non-typhoid Salmonella-triggered arthritis in the left hip. The patient recovered uneventfully after 6-month-long antibiotics treatment. Clinicians involved in transplantation should be aware of the possibility that transplant recipients, like other immunocompromised individuals, are at risk of salmonellosis and therefore require careful clinical and microbiological evaluation, with the goals of prevention and early recognition of infection.
Adrenal Cortex Hormones ; Anti-Bacterial Agents ; Arthritis ; Arthritis, Infectious* ; Bacteria ; Communicable Diseases ; Gastroenteritis ; Hip ; HIV ; Humans ; Immunotherapy ; Liver Transplantation ; Liver* ; Salmonella Infections ; Salmonella typhi ; Salmonella* ; Transplantation*

Typhoid fever, a serious systemic infection caused by Salmonella enterica serovar Typhi, breaks out in developing countries. However, existing vaccines only induce relatively low protective effects with humoral responses and do not stimulate secondary immune response, especially to young people. The objective of this study is to evaluate the immunogenicity of the vaccine containing virulence capsular polysaccharide (Vi) conjugated with the optimal ratios of non-toxic variant of diphtheria toxin (CRM(197)) in mice. Six-week-old BALB/c female mice were injected intraperitoneally three times at intervals of 14 days and sera were collected on days 0, 14, 28, 42 and 56 post-injection. The efficacy of the vaccine was evaluated by comparing between negative control group injected with PBS and vaccine groups injected with Vi or Vi-CRM(197) conjugate of different ratio. Vi and CRM(197)-specific antibody responses were evaluated using enzyme-linked immunosorbent assay. The result showed that Vi-CRM(197)-1 group revealed the highest and significant Vi-specific IgG immune responses among the other groups and Vi group (p < 0.01). In conclusion, Vi-CRM(197)-1 conjugate vaccine induced the highest humoral immune response in mice and may be used as an effective vaccine to replace the existing typhoid vaccine for infants under 2 years old.
Animals ; Antibody Formation ; Child, Preschool ; Developing Countries ; Diphtheria Toxin ; Enzyme-Linked Immunosorbent Assay ; Female ; Humans ; Immunity, Humoral ; Immunoglobulin G ; Infant ; Mice* ; Salmonella enterica* ; Salmonella typhi* ; Salmonella* ; Typhoid Fever ; Typhoid-Paratyphoid Vaccines ; Vaccines ; Virulence

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*

Prompt antibiotic treatment reduces the incidence of complications such as liver abscesses, pyelonephritis, and osteomyelitis in patients with typhoid fever. Renal or liver abscesses are especially rare in patients without underlying disease or predisposing factors. The occurrence of both renal and liver abscesses in a patient with typhoid fever has not been reported. Although the prevalence of typhoid fever in Korea has decreased, it is still an important disease owing to increased opportunities for the occurrence of waterborne diseases with climate warming and group feeding, and the increased numbers of tourists and foreigners visiting Korea. We present a patient with no underlying disease or predisposing factors who developed both renal and liver abscesses caused by nalidixic acid-resistant Salmonella typhi after a trip to Nepal. He was treated successfully with percutaneous drainage of the renal abscess and high-dose ciprofloxacin.
Abscess ; Ciprofloxacin ; Climate ; Drainage ; Drug Resistance ; Emigrants and Immigrants ; Humans ; Incidence ; Korea ; Liver ; Liver Abscess ; Nalidixic Acid ; Nepal ; Osteomyelitis ; Prevalence ; Pyelonephritis ; Salmonella ; Salmonella typhi ; Typhoid Fever