A case of liver abscess co-infected with Desulfovibrio desulfuricans and Escherichia coli and review of the literature.

A 73-year-old woman was admitted with consciousness disturbance following a fever. Abdominal computed tomography revealed a large liver abscess with which the presence of Desulfovibrio desulfuricans and Escherichia coli was confirmed by thorough blood and abscess content culture. Empiric meropenem treatment was switched to cefoperazone/sulbactam, followed by ampicillin/sulbactam based on susceptibility testing. Desulfovibrio desulfuricans is a common bacterium that rarely causes liver abscess and may be overlooked during co-infection due to overgrowth of the accompanying bacteria. Clinicians should bear Desulfovibrio desulfuricans in mind and select the appropriate antibiotics according to susceptibility testing when anaerobic bacteria are detected in a liver abscess.

Lawsonia intracellularis in the feces of wild rodents and stray cats captured around equine farms.

BACKGROUND: Proliferative enteropathy is a global enteric disease of particular importance in pigs. The causative bacterium, Lawsonia intracellularis, has a wide range of susceptible host species. Recently, L. intracellularis has been recognized as an etiologic agent of an emerging enteric disease in foals called equine proliferative enteropathy (EPE). The presence of L. intracellularis in nonruminant wildlife has raised questions regarding the role of these species in EPE transmission. RESULTS: This study investigated exposure to L. intracellularis in wild rodents and feral cats from eight farms with confirmed EPE. Serum (42) and fecal (40) samples from resident foals and fecal samples (131), intestinal mucosa tissues (14), and mesenteric lymph nodes (14) from wild and feral animals were collected for the evaluation of the farm status and the molecular detection of L. intracellularis following the diagnosis of EPE in index cases. Fresh feces from wild rodents and feral cats were collected from the ground while walking the premises or after trapping the animals using live traps. A total of 3 brown rats, 7 house mice, 1 striped field mouse, 2 grey red-backed voles, and 3 feral cats showed evidence of prior exposure to L. intracellularis. CONCLUSIONS: Our data add to increasing evidence demonstrating the potential for L. intracellularis transmission and infection in wild rodents and feral cats and provide possible evidence of interspecies transmission. The exposure of wild rodents and feral cats provides potential evidence for the spillover of L. intracellularis to wildlife species and raises the question of spillback to horses. Additionally, these animals may represent an indicator of environmental exposure or may be actively involved in the transmission of L. intracellularis to foals by acting as potential reservoir/amplifier hosts. This study is the first to demonstrate the magnitude of L. intracellularis shedding in the feces of wild rodents and feral cats and to indicate the significant infection risk that wild rodents and feral cats pose to naïve horses in South Korea.

Serological profile, seroprevalence and risk factors related to Lawsonia intracellularis infection in swine herds from Minas Gerais State, Brazil.

BACKGROUND: Lawsonia intracellularis is the etiologic agent of proliferative enteropathy, which causes diarrhea in several animal species, including swine. Serology can be used both to determine the prevalence of antibodies against a specific pathogen in a herd and to obtain the serological profile, which is used to determine the dynamics of infection in the herd. The objective of this study was to determine the serological profile and seroprevalence of anti-L. intracellularis antibodies in swine herds from intensive production regions of Minas Gerais, Brazil, and to identify the risk factors related to the herd-level seropositivity. RESULTS: A total of 2999 serum samples were collected for this cross-sectional study in the four major regions of intensive swine production in Minas Gerais, Brazil. To obtain better estimates and increase the external validity of the seroprevalence, the sample data were weighted based on the pig population of each herd, the stratum in which the herd was classified and the swine population of the region where each herd was located. A questionnaire was used to identify potential risk factors related to this herd-level seropositivity. The overall weighted prevalence in Minas Gerais was 34.7% (95% confidence interval: 32.12 - 37.20%), and there was no significant difference among the sampled regions, with the seroprevalence rates ranging between 32.06 and 37.66%. Finishing pigs were the most prevalent among the sampled categories. Among the evaluated risk factors, "cleaning before disinfecting" had a negative impact in the seroprevalence (p < 0.05) and was considered a protective factor. CONCLUSIONS: The anti-L. intracellularis antibodies were detected in all of the investigated herds in Minas Gerais, which indicated a wide distribution of the agent in the state. The predominant serological profile was consistent with the dynamics of infection previously observed in pig herds in other countries with similar antimicrobial usage, in which the nursery pigs usually show the lowest seroprevalence and the finishing pigs exhibit the highest. Herds that adopt the practice of "cleaning before disinfection" can decrease their L. intracellularis antibody seropositivity.

Seroprevalence of porcine proliferative enteropathy among wild boars in the Republic of Korea.

BACKGROUND: The importance of the wild boar as a reservoir of Lawsonia intracellularis was assessed by investigating the seroprevalence of this pathogen among wild boars in the Republic of Korea. The extent of exposure to L. intracellularis among wild boars (Sus scrofa coreanus) was monitored by a country-wide serological survey using an immunoperoxidase monolayer assay. RESULTS: In this study, antibodies to L. intracellularis were observed in 165 of 716 clinically healthy wild boars tested. The overall apparent prevalence calculated directly from the sample and the true prevalence calculated based on the accuracy of the test method were 23.0% (95% confidence interval: 20.0-26.3%) and 25.6% (95% confidence interval: 23.9-27.2%), respectively. Serologically positive animals were found in all the tested provinces. CONCLUSIONS: Our results confirm that L. intracellularis is present in the wild boar population worldwide, even in Far East Asia. Despite the high seroprevalence shown in wild boars, further studies are warranted to evaluate their potential as a reservoir species because seroprevalence does not prove ongoing infection nor shedding of the bacteria in amounts sufficient to infect other animals. It should also be determined whether the wild boar, like the domestic pig, is a natural host of L. intracellularis.

Development and validation of an enzyme-linked immunosorbent assay for the diagnosis of porcine proliferative enteropathy.

The objective of this study was to develop an indirect enzyme-linked immunosorbent assay (ELISA) using a sonicated pure culture of Lawsonia intracellularis as the antigen (So-ELISA). A total of 332 serum samples, consisting of 232 experimentally infected animals and 100 animals naturally infected with L. intracellularis, were used to assess the diagnostic sensitivity. Three hundred and fifty-five sera from uninfected animals were used to determine the diagnostic specificity. The receiver operating characteristic and mean +3 standard deviation of optical density (OD) values from uninfected animals were used for selecting cut-off points. The diagnostic accuracy of So-ELISA was considered to be high as the area under the curve index was 0.991 with 0.0029 standard error. The optimal cut-off for So-ELISA was set at 0.45 OD with 89.8% sensitivity and 99.4% specificity based on a combination of good sensitivity and high specificity. No cross-reactivity was found in sera from pigs exposed to Brachyspira pilosicoli, B. hyodysenteriae, Campylobacter mucosalis, C. jejuni, or C. coli. Inter- and intracoefficient of variation of all control sera tested with So-ELISA was less than 10%. The observed agreements between So-ELISA and the immunoperoxidase monolayer assay tested with experimental challenge animals and field samples were 95.08% with 0.88 kappa and 90.65% with 0.74 kappa value, respectively. So-ELISA was able to detect the seroconversion of infected animals at 2 to 4 weeks after exposure to L. intracellularis. Based on the validation results, So-ELISA could be used as an alternative serology for proliferative enteropathy diagnosis.

Evaluation of a novel enzyme-linked immunosorbent assay for serological diagnosis of porcine proliferative enteropathy.

A specific enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to the porcine pathogen Lawsonia intracellularis was developed and evaluated using sera from naïve, naturally infected as well as experimentally infected pigs. On the basis of 37 serum samples collected from experimentally infected pigs and 62 serum samples from naturally infected pigs the sensitivity of the ELISA was calculated to 98.0%. The specificity of the test was 99.3%, calculated on the basis of 273 serum samples collected in six herds free of L. intracellularis after medicated eradication. The novel ELISA was a specific and sensitive method for detecting specific antibodies, and may be a good alternative to the existing serological tests for L. intracellularis. It may be usable for diagnosis of proliferative enteropathy and for determination of a herd's epidemiologic status.

Naturally acquired Lawsonia intracellularis infection in pigs studied from weaning to slaughter by indirect immunofluorescence antibody test and polymerase chain reaction on faeces.

The course of naturally acquired Lawsonia intracellularis infection was studied in 41 pigs by testing blood and faeces samples collected four to seven times from before weaning to slaughter 5 months old. At slaughter, a sample of ileum was taken for histopathology. In the first sampling when the pigs were 2-4 weeks old maternally derived IgG against L. intracellularis was demonstrated by immunofluorescence antibody test in nine pigs whereas the bacterium was detected by PCR in faeces from six pigs. The maternally derived antibodies did not prevent pigs from becoming infected as seven pigs later on shed and/or were seropositive for L. intracellularis. The lowest prevalence of L. intracellularis was observed in 6-13 weeks old pigs and it seemed as though L. intracellularis in early infected pigs only activates a minor antibody response. At slaughter 66% of the pigs were found positive by immunofluorescence antibody test compared to 24% by immunohistochemistry on ileal samples. Thus, applied at the time of slaughter the antibody test appeared to be a highly sensitive ante-mortem diagnostic tool for identifying L. intracellularis exposed pigs with or without current proliferative enteropathy.