We evaluated the association between typhoid fever and Helicobacter pylori infection, as the latter microorganism may influence gastric acid secretion and consequently increase susceptibility to Salmonella typhi infection. Anti-H. pylori IgG and IgA antibody titres (ELISA) and gastrin concentration (RIA) were determined in the plasma of 87 blood culture-confirmed typhoid fever cases (collected after clinical recovery) and 232 random healthy controls without a history of typhoid fever, in the Jatinegara district, Jakarta. Patients with typhoid fever more often than controls were seropositive for H. pylori IgG (67% vs. 50%, P<0·008), when antibody titres were dichotomized around median titres observed in controls. H. pylori IgA seropositivity was not associated with typhoid fever. Plasma gastrin concentrations indicative of hypochlorhydria (i.e. gastrin ⩾25 or ⩾100 ng/l) were not significantly elevated in typhoid fever cases compared to controls (P=0·54 and P=0·27 respectively). In a multivariate analysis, typhoid fever was independently associated with young age (<33 years, median age of the controls) [odds ratio (OR) 7·93, 95% confidence interval (CI) 3·90–16·10], and H. pylori IgG seropositivity (OR 1·93, 95% CI 1·10–3·40). Typhoid fever was independently associated with H. pylori IgG seropositivity, but not with elevated gastrin concentration. Therefore, the association suggests a common risk of environmental exposure to both bacteria, e.g. poor hygiene, rather than a causal relationship via reduced gastric acid production.

A total of 1873 strains from human origin and 4283 strains from non-human origin of Salmonella enterica serotypes Typhimurium, Enteritidis, Heidelberg, Hadar and Virchow, collected over three years 1993, 1997 and 2000, were examined in order to determine the rate of antimicrobial resistance to 12 antimicrobial drugs. The objective of the study was to describe and to compare the evolution of the main resistance types in human and non-human isolates, focusing on the poultry sector. The evolution and the rates of antimicrobial resistances for the five serotypes, with the exception of Virchow, were almost comparable in strains isolated from human and non-human sources over the period studied. The most striking result concerning single resistance was the spectacular increase of the resistance frequency to nalidixic acid for the strains belonging to serotypes Hadar and Virchow, especially in the poultry food sector (14% in 1993 vs. 72% in 2000 for Salmonella Virchow, 4% in 1993 vs. 70% in 2000 for Salmonella Hadar) and also in human isolates (24% in 1997 vs. 48% in 2000 for S. Virchow, 31% in 1997 vs. 78% in 2000 for S. Hadar). In addition to the classical resistance to ampicillin, streptomycin, sulphonamide, chloramphenicol and tetracycline (ASSuCT resistance type), which stabilized between 1997 and 2000, the emergence of a new resistance type was observed.

Fifty-seven Salmonella Typhimurium strains isolated from poultry, swine and animal feed in Poland during the years 1979–1998 and 2000–2002 were analysed with conventional and molecular techniques. Antimicrobial resistance as well as multiresistance was found, respectively, in 80·1% and 56·1% of the isolates and most frequently among isolates from 2000–2002. Of several phage types noted, DT104 was prevalent among poultry, swine and feed isolates. DT104, U302 and non-typable strains had a multiple resistant profile (ACSSuT) due to the presence of class I integrons. Pulse-field gel electrophoresis of XbaI and BlnI digest showed high genomic similarity between the strains and confirmed clonal spread of S. Typhimurium infections. Plasmid profiling allowed further differentiation of the strains. We have, therefore, confirmed the appearance of S. Typhimurium DT104 showing genome integrated integron-mediated antimicrobial resistance in Poland. These findings are significant for public and animal health risks and document the dissemination of DT104 epidemic strains into new geographical regions.

For epidemiological investigations of the most common and non-host-adapted Salmonella serotypes, such as Typhimurium, highly discriminatory approaches are essential. In the present study, we evaluated three genotyping methods; amplified fragment length polymorphism (AFLP), pulsed-field gel electrophoresis (PFGE) and repetitive palindromic extragenic–PCR (Rep–PCR) using 40 isolates. AFLP showed the highest discriminatory index (0·939), resolution and throughput. To determine clonality of Salmonella Typhimurium isolates and epidemiological relatedness in different commercial pig production units, we employed AFLP in combination with antimicrobial resistance pattern and phage typing. Salmonella serovar Typhimurium isolates (n=196) obtained from a longitudinal study of 18 pig farms over a 3-year period were studied. Using this approach, 16 distinct clonal types were identified. We found two common multidrug- resistant patterns including AmCmStSuTe and AmKmStSuTe. Two commonly multidrug- resistant phage types that are of known public health importance, DT104 and DT193, were also common. AFLP differentiated distinct clones within DT104, a phage type previously reported to be clonal. Fourteen of the clonal types were unique to one of the two production systems, showing diversity between independent commercial pig production systems located in the same geographical area. Clonal types obtained from nursery farms and corresponding finishing units were, however, similar.

This study tested the hypothesis of airborne transmission of Salmonella Agona (Trial I) and Salmonella Typhimurium (Trial II) in weaned pigs. The trials were performed using stainless-steel/glass isolation cabinets connected by air ducts to permit an unidirectional airflow from cabinet 1 (two control pigs) to cabinet 3 (two sentinel pigs), passing through cabinet 2 (two inoculated pigs). Air samples, pooled faecal samples from the floor and rectal swabs were collected daily and assessed by culture and PCR. A fumigation chamber and rubber gloves coupled to the cabinets allowed sampling without opening the system. Trials I and II lasted 15 and 19 days respectively. The recovery of S. Agona and S. Typhimurium and detection of seroconversion in sentinel pigs indicate that airborne Salmonella transmission in weaned pigs over short distances is possible. Further studies on the role of aerosols in the epidemiology of Salmonella in intensive pig production should be performed.