Helicobacter pylori infection and typhoid fever in Jakarta, Indonesia

Influence of Physicochemical Properties of Iron Oxide Nanoparticles on Their Antibacterial Activity

The increasing occurrence of infectious diseases caused by antimicrobial resistance organisms urged the necessity to develop more potent, selective, and safe antimicrobial agents. The unique magnetic and tunable properties of iron oxide nanoparticles (IONPs) make them a promising candidate for different theragnostic applications, including antimicrobial agents. Though IONPs act as a nonspecific antimicrobial agent, their antimicrobial activities are directly or indirectly linked with their synthesis methods, synthesizing precursors, size, shapes, concentration, and surface modifications. Alteration of these parameters could accelerate or decelerate the production of reactive oxygen species (ROS). An increase in ROS role production disrupts bacterial cell walls, cell membranes, alters major biomolecules (e.g., lipids, proteins, nucleic acids), and affects metabolic processes (e.g., Krebs cycle, fatty acid synthesis, ATP synthesis, glycolysis, and mitophagy). In this review, we will investigate the antibacterial activity of bare and surface-modified IONPs and the influence of physiochemical parameters on their antibacterial activity. Additionally, we will report the potential mechanism of IONPs' action in driving this antimicrobial activity.

Pre-existing Helicobacter pylori serum IgG enhances the vibriocidal antibody response to CVD 103-HgR live oral cholera vaccine in Malian adults

Accumulating evidence indicates that persistent Helicobacter pylori gastric infection influences immune responses to oral enteric vaccines. We studied the association between pre-existing H. pylori serum IgG and serum pepsinogens levels (PGs) as markers of gastric inflammation and the immune response to single-dose live oral cholera vaccine CVD 103-HgR in Malian adults. Baseline sera obtained during a phase 2 safety/immunogenicity clinical trial of cholera vaccine CVD 103-HgR among 93 healthy Malian adults were tested for H. pylori IgG antibodies and PGI and PGII levels using enzyme linked immunosorbent assays. Overall 74/93 (80%) vaccine recipients were H. pylori IgG seropositive at baseline. Vibriocidal antibody seroconversion (≥ fourfold increase 14 days following administration of CVD 103-HgR compared to baseline) among vaccine recipients was 56%. However, vibriocidal antibody seroconversion was markedly higher among H. pylori seropositives than seronegatives 64% vs. 26% (p = 0.004); adjusted relative risk: 2.20 (95% confidence intervals 1.00–4.80; p = 0.049). Among H. pylori seropositive vaccine recipients, there were no significant associations between PGI, PGII and PGI:PGII levels and vibriocidal seroconversion. The enhanced seroconversion to oral cholera vaccine CVD 103-HgR among H. pylori seropositive African adults provides further evidence of the immunomodulating impact of H. pylori on oral vaccine immunogenicity.

Homologous and heterologous re-challenge with Salmonella Typhi and Salmonella Paratyphi A in a randomised controlled human infection model

Enteric fever is a systemic infection caused by Salmonella Typhi or Paratyphi A. In many endemic areas, these serovars co-circulate and can cause multiple infection-episodes in childhood. Prior exposure is thought to confer partial, but incomplete, protection against subsequent attacks of enteric fever. Empirical data to support this hypothesis are limited, and there are few studies describing the occurrence of heterologous-protection between these closely related serovars. We performed a challenge-re-challenge study using a controlled human infection model (CHIM) to investigate the extent of infection-derived immunity to Salmonella Typhi or Paratyphi A infection. We recruited healthy volunteers into two groups: naïve volunteers with no prior exposure to Salmonella Typhi/Paratyphi A and volunteers previously-exposed to Salmonella Typhi or Paratyphi A in earlier CHIM studies. Within each group, participants were randomised 1:1 to oral challenge with either Salmonella Typhi (104 CFU) or Paratyphi A (103 CFU). The primary objective was to compare the attack rate between naïve and previously challenged individuals, defined as the proportion of participants per group meeting the diagnostic criteria of temperature of ≥38°C persisting for ≥12 hours and/or S. Typhi/Paratyphi bacteraemia up to day 14 post challenge. The attack-rate in participants who underwent homologous re-challenge with Salmonella Typhi was reduced compared with challenged naïve controls, although this reduction was not statistically significant (12/27[44%] vs. 12/19[63%]; Relative risk 0.70; 95% CI 0.41-1.21; p = 0.24). Homologous re-challenge with Salmonella Paratyphi A also resulted in a lower attack-rate than was seen in challenged naïve controls (3/12[25%] vs. 10/18[56%]; RR0.45; 95% CI 0.16-1.30; p = 0.14). Evidence of protection was supported by a post hoc analysis in which previous exposure was associated with an approximately 36% and 57% reduced risk of typhoid or paratyphoid disease respectively on re-challenge. Individuals who did not develop enteric fever on primary exposure were significantly more likely to be protected on re-challenge, compared with individuals who developed disease on primary exposure. Heterologous re-challenge with Salmonella Typhi or Salmonella Paratyphi A was not associated with a reduced attack rate following challenge. Within the context of the model, prior exposure was not associated with reduced disease severity, altered microbiological profile or boosting of humoral immune responses. We conclude that prior Salmonella Typhi and Paratyphi A exposure may confer partial but incomplete protection against subsequent infection, but with a comparable clinical and microbiological phenotype. There is no demonstrable cross-protection between these serovars, consistent with the co-circulation of Salmonella Typhi and Paratyphi A. Collectively, these data are consistent with surveillance and modelling studies that indicate multiple infections can occur in high transmission settings, supporting the need for vaccines to reduce the burden of disease in childhood and achieve disease control. Trial registration NCT02192008; clinicaltrials.gov.

Helicobacter pylori infection and risk of salmonella infection

Helicobacter pylori (H pylori) infection is the most frequent infection worldwide and it has been postulated that it predisposes to multiple enteric pathogens and diarrheal diseases. Salmonella infection is common in tropical and under developed communities and is associated with wide range of diseases from gastroenteritis to typhoid fever. This study aimed at detecting the impact of H pylori infection on the incidence of salmonella infections.The study participants were sampled from cohorts of patients in four university hospitals in different Egyptian Governorates. Their age ranged from 20 to 59 years and followed up for a rising Widal test. Case patients (n = 109) were subjects who visited the outpatient clinic because of diarrhea and typhoid like illness. They were either positive for H pylori stool antigen (n = 53) or negative to it (n = 56). All patients were subjected to thorough history taking, clinical examination, routine laboratory investigations, abdominal ultrasonography, H pylori stool antigen detection, and serial Widal test assay.The proportion of salmonella-infected subjects was lower among case patients with H pylori infection (22.6%) than among those negative for H pylori (33.9%) albeit not statistically significant (adjusted odds ratio [OR], 0.57; 95% confidence interval [CI], 0.24-1.33; P = .21). The association persisted nonsignificant after adjusting for sociodemographic variables (adjusted OR, 0.5; 95% CI, 0.18-1.39; P = .18). In a multivariate analysis that adjusted for sex, dietary habits, socioeconomic status, and educational level subjects who eat outdoors were associated with a significantly greater risk of salmonella typhi infection.Our findings suggest that there is no association between H pylori infection and salmonella infection in patients presented with typhoid fever or typhoid like illness.

Does Helicobacter pylori Infection Play a Role in Susceptibility to Brucellosis?

Brucellosis is endemic in Iran. Several studies have shown that brucellosis is associated with other infectious diseases. This study aimed to determine the relationship between Helicobacter pylori (HP) and brucellosis. In this case-control study, 100 patients with brucellosis as cases and 200 participants without brucellosis as controls were evaluated. To compare the prevalence of HP in the 2 groups, odds ratios and confidence intervals for every variable were analyzed using logistic regression models after adjustment for confounding factors. The results obtained in patients with brucellosis showed that fever, sweating, and joint pain were the most prevalent clinical symptoms. In addition, compared with the control group, there was a significant relationship between the IgM antibody to HP and brucellosis infection (estimated odds ratio 2.74; 95% CI: 1.5-4.9) (p = 0.001). Acute infection with HP was associated with brucellosis and increased the risk of brucellosis infection.

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

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

Helicobacter pylori infection affects immune responses following vaccination of typhoid-naive U.S. adults with attenuated Salmonella typhi oral vaccine CVD 908-htrA

BACKGROUND

 We examined the association between Helicobacter pylori infection and the immune response following oral immunization of US adults with attenuated Salmonella Typhi vaccine CVD 908-htrA.

METHODS

 Baseline sera from 74 volunteers without a history of typhoid fever who were immunized orally with CVD 908-htrA were tested by enzyme-linked immunosorbent assay for immunoglobin G (IgG) antibodies to H. pylori, hepatitis A antibodies (a marker of low socioeconomic status and exposure to enteric infections), and pepsinogen (PG) I and II levels (measures of gastric inflammation). IgG against S. Typhi lipopolysaccharide (LPS) O and flagella was measured before and 28 days following immunization; a ≥4-fold increase in titer from baseline constituted seroconversion.

RESULTS

 Seroconversion of S. Typhi IgG LPS antibodies was significantly higher among vaccinees infected with H. pylori versus uninfected subjects: adjusted odds ratio (OR) 3.8, 95% confidence interval (CI), 1.1-12.6 (P = .03). A low PG I:PG II ratio (<5), indicating more advanced corpus gastritis, increased the odds of seroconversion of IgG S. Typhi flagella antibody (adjusted OR 6.4, 95% CI, 1.3-31.4; P = .02). Hepatitis A infection did not influence the immune response to CVD 908-htrA.

CONCLUSIONS

 H. pylori infection and gastric inflammation may enhance humoral immunity to oral attenuated S. Typhi vaccine.

Unintended consequences of Helicobacter pylori infection in children in developing countries: iron deficiency, diarrhea, and growth retardation

Helicobacter pylori infection is predominantly acquired early in life. The prevalence of the infection in childhood is low in developed countries, whereas in developing countries most children are infected by 10 y of age. In poor resource settings, where malnutrition, parasitic/enteropathogen and H. pylori infection co-exist in young children, H. pylori might have potentially more diverse clinical outcomes. This paper reviews the impact of childhood H. pylori infection in developing countries that should now be the urgent focus of future research. The extra-gastric manifestations in early H. pylori infection in infants in poor resource settings might be a consequence of the infection associated initial hypochlorhydria. The potential role of H. pylori infection on iron deficiency, growth impairment, diarrheal disease, malabsorption and cognitive function is discussed in this review.

Childhood hygienic practice and family education status determine the prevalence of Helicobacter pylori infection in Iran

BACKGROUND

Management of Helicobacter pylori, a causative agent of gastrointestinal diseases is an important health problem in most countries. The main reasons include poorly defined epidemiological status and unrecognized mode of bacterial transmission. Our objective was to investigate the prevalence of H. pylori infection in a representative population of Iran and to evaluate possible risk factors for the H. pylori infection.

MATERIALS AND METHODS

In this cross-sectional study, 2561 healthy individuals aged 18-65 years (mean age, 35.5 years) were selected out of 12,100,000 inhabitants of Tehran province by cluster sampling. Infection with H. pylori was evaluated by detection of anti-H. pylori IgG antibody in serum. Sociodemographic status of each subject was determined by filling up a questionnaire.

RESULTS

Prevalence of H. pylori infection was 69% and was correlated with increasing age. The highest infection rate (79.2%) was seen in individuals 46-55 years old. No association was detected between H. pylori positivity and gender. Low education of the study subjects; low father's and mother's education; poor tooth brushing habit; crowded families in childhood; and lack of household bath, hygienic drinking water, and swage disposal facility in childhood were determined as possible risk factors.

CONCLUSIONS

The rate of prevalence of H. pylori infection was higher than developed countries. Low socioeconomic status, poor sanitary indications, and crowded families in childhood were related to high prevalence of H. pylori infection in Iran. Accordingly, fecal-oral and oral-oral routes could be considered as the main pathways of transmission of H. pylori.

A new model for the transmission of Helicobacter pylori: role of environmental reservoirs as gene pools to increase strain diversity

Twenty-five years after the first successful cultivation and isolation of Helicobacter pylori, the scientific community is still struggling to understand the way(s) this bacterium is transmitted among the human population. Here, both epidemiologic and microbiologic evidence addressing this matter is reviewed and explored to conclude that most H. pylori successful colonizations are derived from direct person-to-person contact and that even though exposure of humans to H. pylori from environmental sources is a very common event, in most occasions the host is able to fight off infection. In addition, under a new model developed here, we propose that the near elimination of environmental reservoirs is the main responsible for the lower prevalence observed in the more industrialized countries by acting on two levels: by decreasing the number of direct infections and by diminishing the number of intraspecies recombination events for producing strain variation within H. pylori.

Childhood Helicobacter pylori infection and growth impairment in developing countries: a vicious cycle?

We hypothesize that infection with the gastric pathogen Helicobacter pylori in children in developing countries is the initiator of a vicious cycle of events that result ultimately in malnutrition and growth impairment. Acute infection with H. pylori is accompanied by hypochlorhydria, which facilitates the acquisition of other enteropathogens because of removal of the gastric acid barrier, which then results in diarrheal disease and iron-deficiency anemia. This is likely to occur most frequently in developing regions where the prevalence of H. pylori infection is disproportionately high and multiple enteric coinfections are common. The consequent synergistic impact of diarrheal disease and micronutrient deficiency on growth and cognitive function in children has significant public health implications for socioeconomic development in these countries.

Low prevalence of Helicobacter pylori infection in young children in the Netherlands

AIM OF THE STUDY

To investigate the seroprevalence of Helicobacter pylori infection in young children from the general population in The Netherlands.

METHODS

Determination of IgG antibodies against H. pylori, using an enzyme-linked immunosorbent assay technique [cutoff 0.32 Absorption Index (AI)], in serum from 1258 children who were 2-4 years of age. The serum was obtained from a serum bank of 6127 children who attended the community child healthcare centers in the Dutch province of Zuid-Holland.

RESULTS

In general, we found a seroprevalence of 1.2% of H. pylori infection, with a significant difference between the children with parents who were both Dutch (0.5%), and the children with at least one non-Dutch parent (2.6%) (P<0.001).

CONCLUSIONS

The prevalence of H. pylori infection in young infants in the general population in The Netherlands is low. Children with at least one non-Dutch parent form a risk group, however, for H. pylori infection in The Netherlands.

Epidemiology of Helicobacter pylori infection

Differences may occur in the mode of transmission of Helicobacter pylori between developed and developing countries: direct human-to-human contacts have been suggested as the primary route in the former while the fecal-oral route, also, through contaminated water, in the latter. Data on intrafamilial transmission of H. pylori among children continue to be produced. The importance of low socioeconomic conditions on the acquisition of H. pylori infection has been confirmed in a number of population-based studies. Due to the improvement of living standards, the prevalence of the infection has fallen dramatically in many countries. It varies from 8.9 to 72.8% among children from developed and developing countries, respectively, the re-infection rate being also significantly higher in the latter. Conflicting data have been reported on the effect of breastfeeding against H. pylori colonization in infancy as well as on the occupational risk for acquiring H. pylori. This review summarizes recent results from the literature on these topics.