Procalcitonin levels in salmonella infection

Aim:

Procalcitonin (PCT) as a diagnostic marker for bacteremia and sepsis has been extensively studied. We aimed to study PCT levels in Salmonella infections whether they would serve as marker for early diagnosis in endemic areas to start empiric treatment while awaiting blood culture report.

Materials and Methods:

BACTEC blood culture was used to isolate Salmonella in suspected enteric fever patients. Serum PCT levels were estimated before starting treatment.

Results:

In 60 proven enteric fever patients, median value of serum PCT levels was 0.22 ng/ml, values ranging between 0.05 and 4 ng/ml. 95% of patients had near normal or mild increase (<0.5 ng/ml), only 5% of patients showed elevated levels. Notably, high PCT levels were found only in severe sepsis.

Conclusion:

PCT levels in Salmonella infections are near normal or minimally increased which differentiates it from other systemic Gram-negative infections. PCT cannot be used as a specific diagnostic marker of typhoid.     

mig-14 is a horizontally acquired, host-induced gene required for salmonella enterica lethal infection in the murine model of typhoid fever

We have characterized a host-induced virulence gene, mig-14, that is required for fatal infection in the mouse model of enteric fever. mig-14 is present in all Salmonella enterica subspecies I serovars and maps to a region of the chromosome that appears to have been acquired by horizontal transmission. A mig-14 mutant replicated in host tissues early after infection but was later cleared from the spleens and livers of infected animals. Bacterial clearance by the host occurred concomitantly with an increase in gamma interferon levels and recruitment of macrophages, but few neutrophils, to the infection foci. We hypothesize that the mig-14 gene product may repress immune system functions by interfering with normal cytokine expression in response to bacterial infections.     

A nosocomial outbreak of fluoroquinolone-resistant salmonella infection

BACKGROUND: Infection with fluoroquinolone-resistant strains of salmonella is rare, as is nosocomial salmonella infection. We describe the first recognized outbreak of fluoroquinolone-resistant salmonella infections in the United States, which occurred in two nursing homes and one hospital in Oregon. METHODS: We interviewed medical staff and reviewed patients' charts and death certificates. In Nursing Home A we conducted a case-control study. Patients were defined as residents of the nursing home from whom fluoroquinolone-resistant Salmonella enterica serotype Schwarzengrund was isolated between February 1996 and December 1998. Controls were residents with similar medical conditions whose cultures did not yield salmonella. We compared isolates using pulsed-field gel electrophoresis and sequence analysis. We reviewed pharmacy records to compare the use of fluoroquinolone among several nursing homes. RESULTS: Eleven patients with fluoroquinolone-resistant salmonellosis were identified at two nursing homes. The index patient had been hospitalized in the Philippines and had probably acquired the infection there. Transmission was probably direct (from patient to patient) or through contact with contaminated surfaces. Treatment with fluoroquinolones during the six months before a culture was obtained was associated with a significant risk of salmonella infection (4 of 5 patients had taken fluoroquinolones, as compared with 2 of 13 controls; odds ratio, 22.0; 95 percent confidence interval, 1.06 to 1177). The patients were not significantly more likely than the controls to have taken other antibiotics. More fluoroquinolones were used at Nursing Home A than at similar nursing homes in Oregon. The isolates from the outbreak had similar patterns on pulsed-field gel electrophoresis and the same gyrA mutations. The isolates from the outbreak were also similar to the only previous isolate of fluoroquinolone-resistant salmonella in the United States, which came from a patient in New York who had been transferred from a hospital in the Philippines. CONCLUSIONS: We describe a prolonged nosocomial outbreak of infection with fluoroquinolone-resistant S. enterica serotype Schwarzengrund. More such outbreaks are likely in institutional settings, particularly those in which there is heavy use of antimicrobial agents.     

Evidence of transmission of verocytotoxin-producing Escherichia coli O111 from a cattle stable to a child

Infections with verocytotoxigenic Escherichia coli (VTEC) other than O157 have been assumed to have the same epidemiology as those with VTEC O157, but the source of infection is rarely defined for sporadic cases. This report describes a child with VTEC O111:H- infection who was probably infected by playing in a cattle stable and/or by drinking raw milk from the cows in this stable. E. coli O111 isolates colonising the cattle were indistinguishable from the patient isolate by the use of serotyping, pulsed-field gel electrophoresis, and virulence profiling.     

The initial suppression of bacterial growth in a salmonella infection is mediated by a localized rather than a systemic response

Mice were infected intravenously with two antibiotic resistance tagged variants of the same S. typhimurium strain given in close succession, or simultaneously with strains of different virulence. The first manifestation of acquired resistance--suppression of exponential bacterial growth in liver and spleen--occurred independently for the different strains in the same individuals, implying that it is due to localized rather than systemic events. This early suppression of bacterial growth was ablated by whole body X-irradiation (800R), whereas the immediately preceding phase of exponential growth (Ity controlled innate resistance) was not affected. Transfer of spleen cell suspensions from infected mice into syngeneic recipients conferred protection by suppressing the growth of an intravenous challenge. Pre-treatment of the suspensions to deplete them of macrophages abolished their protective capacity, while depletion of T-cells did not. Mice deficient in T-cells by adult thymectomy and anti-T-cell monoclonal antibody treatment were able to suppress the growth of an intravenous challenge. Taken collectively, the present data show that the very early phase of acquired resistance to salmonellae, essential for survival, is not the result of systemically developing resistance but a localized event at the site of infection.     

Serological follow-up after non-typhoid salmonella infection in humans using a mixed lipopolysaccharide ELISA

In industrialized countries, non-typhoid salmonella are a frequent cause of bacterial gastroenteritis. Diagnosis is usually made by stool culture, which is labour-intensive and time-consuming. Sensitivity depends on handling of stool samples and delay from illness onset to sampling. We developed an indirect mixed enzyme-linked immunosorbent assay (ELISA) for the detection of human serum antibodies against lipopolysaccharide antigens of the two predominant serovars, Salmonella serovar Enteritidis (S. Enteritidis) and S. Typhimurium. We measured IgA, IgM and IgG in 964 sera from 302 patients with stool culture-confirmed acute salmonella gastroenteritis, in 300 sera from healthy blood donors, and in 147 sera from patients with antibodies against other bacteria. Patient sera were collected within 1 month and approximately 3, 6, and 12 months after illness onset. For sera collected ≤30 days of onset, sensitivity of the ELISA was 92% for S. Enteritidis and 86% for S. Typhimurium, with a specificity of 95% for both serovars. The mixed ELISA is a useful additional tool for the diagnosis of acute salmonella gastroenteritis. It allows rapid analysis of multiple samples, thus can be used for sero-epidemiological studies of large population-based serum collections in order to estimate the population incidence of salmonella infections. Another application is aetiological diagnostics in patients with suspected post-infectious complications such as reactive arthritis, even when faecal shedding of salmonella has ceased.     

Increased resistance of iron-deficient mice to salmonella infection.

Nutritional iron deficiency in mice attenuated Salmonella typhimurium infection compared with both iron-substituted littermates and normal diet control animals.     

Enteric salmonella infection inhibits Paneth cell antimicrobial peptide expression

Paneth cells, highly secretory epithelial cells found at the bases of small intestinal crypts, release a variety of microbicidal molecules, including alpha-defensins and lysozyme. The secretion of antimicrobials by Paneth cells is thought to be important in mucosal host defense against invasion by enteric pathogens. We explored whether enteric pathogens can interfere with this arm of defense. We found that oral inoculation of mice with wild-type Salmonella enterica serovar Typhimurium decreases the expression of alpha-defensins (called cryptdins in mice) and lysozyme. Oral inoculation with Salmonella serovar Typhimurium strains that are heat killed, lack the PhoP regulon, and lack the SPI1 type III secretion system or with Listeria monocytogenes does not have this effect. Salmonella may gain a specific survival advantage in the intestinal lumen by decreasing the expression of microbicidal peptides in Paneth cells through direct interactions between Salmonella and the small intestinal epithelium.     

Primary hepatic leiomyosarcoma in a child with the acquired immunodeficiency syndrome.

We report the first case of acquired immunodeficiency syndrome (AIDS)-related primary hepatic leiomyosarcoma in a 9-year-old girl. The pathologic diagnosis was made on a partial hepatectomy specimen and was confirmed by immunohistochemistry and electron microscopy. No human immunodeficiency virus-related nucleic acid was identified in tumor cells by in situ hybridization. Review of the AIDS-related literature reveals a rising incidence of tumors of smooth muscle origin in human immunodeficiency virus-infected patients. This case study details the eighth pediatric AIDS patient with a tumor of smooth muscle origin and represents the 20th and the youngest patient with primary hepatic leiomyosarcoma to be reported in the world literature.     

Dead cattle, lead and child health

This study was carried out as part of a larger interagency investigation in response to concerns about human health following the death of three cattle from lead poisoning in an old lead mining area in Silvermines, Tipperary. Its aim was to screen for lead toxicity in the local child population. Screening consisted of measurement of blood lead concentrations and the completion of questionnaires regarding exposure to lead and general health. Pre-school and primary school children resident in four surrounding district electoral divisions (DEDs) were specifically targeted. One out of 334 (0.3%) children screened had an elevated blood lead concentration. The geometric mean lead concentration was 2.6 microg/dl which is below the intervention lead concentration of 10 microg/dl recommended by the CDC. The mean lead concentration in those aged under three years was statistically significantly higher than in those aged three years and over (3.4 microg/dl vs 2.5 microg/dl; p=0.000581). No specific health problems were identified by the questionnaires. This study concluded that the elevated environmental lead levels which were demonstrated by other agencies involved in this investigation are not currently being transferred to children. It recommends further blood screening of children in the area and ongoing education to minimise the risk of lead toxicity in the area in the future.     

Antimicrobial susceptibilities of salmonella strains isolated from humans,cattle, pigs,and chickens in the Netherlands from 1984 to 2001

We monitored antimicrobial susceptibility data for Salmonella strains isolated from humans, cattle, pigs, and chickens in The Netherlands from 1984 to 2001 in order to provide insight into the dynamics of resistance over time. The strains were tested for their susceptibilities to seven antimicrobial agents by the agar diffusion method. Resistance was most common in Salmonella enterica subsp. enterica serovar Typhimurium. Among the strains from humans, pigs, and chickens, it was found that the level of resistance of serovar Typhimurium strains to tetracycline, ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole increased from 1984 to 2001. This increase could be attributed to the emergence of multidrug-resistant serovar Typhimurium DT 104. Among the strains from cattle, it was found that the level of resistance of serovar Typhimurium strains, which was already very high in the 1980s, declined during the study period to the same levels as those for the strains from the other species from 1996 to 2001. Serovar Enteritidis isolates remained susceptible during the entire survey period. Among serovar Paratyphi B variation Java strains isolated from chickens, resistance to furazolidone, flumequine, trimethoprim-sulfamethoxazole, and ampicillin emerged, although furazolidone was not used after 1990. Together, the data indicate that the levels and patterns of resistance differed considerably between Salmonella serovars isolated from one host species.