Antimicrobial Susceptibility of Commensal E. coli Isolated from Wild Birds in Umbria (Central Italy).

The role of wildlife, including birds, in antimicrobial resistance is nowadays a speculative topic for the scientific community as they could be spreaders/sources of antimicrobial resistance genes. In this respect, we aimed to investigate the antimicrobial susceptibility of 100 commensal Escherichia coli strains, isolated from wild birds from an Umbrian rescue centre and admitted to the Veterinary Teaching Hospital of Perugia (Central Italy) mainly for traumatic injuries. The possible presence of Salmonella spp. and ESBL-producing E. coli was also estimated. The highest prevalence of resistance was observed for ampicillin (85%) and amoxicillin/clavulanic acid (47%), probably due to their extensive use in human and veterinary medicine. Seventeen out of the one hundred E. coli isolates (17%) displayed a multidrug-resistance profile, including the beta-lactam category, with the most common resistance patterns to three or four classes of antibiotics. Resistance to ciprofloxacin, cefotaxime and ceftazidime exhibited values of 18%, 17% and 15%, respectively. Eight out of the hundred E. coli isolates (8%) were ESBL and seven showed multidrug resistance profiles. Salmonella spp. was not isolated. Resistance to third-generation cephalosporins, also detected in long-distance migratory birds, suggests the need for monitoring studies to define the role of wild birds in antimicrobial resistance circuits.

mcr-1-Mediated Colistin Resistance and Genomic Characterization of Antimicrobial Resistance in ESBL-Producing Salmonella Infantis Strains from a Broiler Meat Production Chain in Italy.

This work aimed to evaluate phenotypically and genotypically the colistin susceptibility of 85 Salmonella Infantis strains isolated in Italy from the broiler production chain, and to apply a whole-genome approach for the determination of genes conferring antimicrobial resistance (AMR). All isolates were tested by the broth microdilution method to evaluate the colistin minimum inhibitory concentrations (MICs). A multiplex PCR was performed in all isolates for the screening of mcr-1, mcr-2, mcr-3 mcr-4, mcr-5 genes and whole-genome sequencing (WGS) of six S. Infantis was applied. Three out of 85 (3.5%) S. Infantis strains were colistin resistant (MIC values ranged from 4 to 8 mg/L) and mcr-1 positive. The mcr-1.1 and mcr-1.2 variants located on the IncX4 plasmid were detected in three different colistin-resistant isolates. The two allelic variants showed identical sequences. All six isolates harbored blaCTXM-1, aac(6')-Iaa and gyrA/parC genes, mediating, respectively, beta-lactam, aminoglycoside and quinolone resistance. The pESI-megaplasmid carrying tet(A) (tetracycline resistance), dfrA1, (trimethoprim resistance) sul1, (sulfonamide resistance) and qacE (quaternary ammonium resistance) genes was found in all isolates. To our knowledge, this is the first report of the mcr-1.2 variant described in S. Infantis isolated from broilers chickens. Our results also showed a low prevalence of colistin- resistance, probably due to a reduction in colistin use in poultry. This might suggest an optimization of biosecurity control both on farms and in slaughterhouses.

Antimicrobial Susceptibility of Escherichia coli and ESBL-Producing Escherichia coli Diffusion in Conventional, Organic and Antibiotic-Free Meat Chickens at Slaughter.

As a result of public health concerns regarding antimicrobial resistance in animal-based food products, conventional poultry companies have turned to 'raised without antibiotics' (ABF) and organic farming systems. In this work, we evaluated the influence of rearing systems on antimicrobial susceptibility in E. coli and extended-spectrum ß-lactamase (ESLB) E. coli diffusion in conventional (C), organic (O) and antibiotic free (ABF) chicken samples collected from cloacal swabs and skin samples in slaughterhouse. The E. coli isolates from conventional (135), antibiotic-free (131) and organic (140) samples were submitted to the Kirby-Bauer method and ESBL E. coli were analyzed by the microdilution test. Conventional samples showed the highest number of strains resistant to ampicillin (89.6%; p < 0.01), cefotaxime (43.7%; p < 0.01), nalidixic acid (57.8%; p < 0.01), ciprofloxacin (44.4%; p < 0.001), and trimethoprim/sulfamethoxazole (62.2%; p < 0.01), with patterns of multi-resistance to three (35.1%) and to four antimicrobials (31.3%), whereas most of the E. coli isolated from antibiotic-free and organic chicken samples revealed a co-resistance pattern (29.2% and 39%, respectively). The highest number of ESBL E. coli was observed in conventional, in both cloacal and skin samples and the lowest in organic (p < 0.001). Our results are consistent with the effect of conventional farming practices on E. coli antimicrobial resistance and ESBL E. coli number, due to the use of antimicrobials and close contact with litter for most of the production cycle.

Immuno- and glyco-histochemistry as a tool to evaluate the oregano supplemented feed effects in pig gut.

Among oregano properties, its antioxidant and antibacterial effects are particularly interesting. Oregano is also able to induce a higher glycoconjugate production in gut, creating a physical barrier against microorganisms. This study evaluated the effects of adding an aqueous extract of oregano (OAE) to the diet of two homogenous groups of pigs during the finisher phase. The diets were as follows: control commercial diet (CTR group) and CTR diet supplemented (2 g/kg) with OAE (O group). Samples of ileum and caecum from the two groups were examined by conventional histochemistry to analyze complex carbohydrates and by immunohistochemistry to detect Bcl-2 Associate X protein (BAX), an indicator of oxidative stress. Glyco-histochemistry showed significant differences between the two groups. Immunohistochemistry revealed a lower presence of BAX in O group. The OAE supplementation improved the production of glycoconjugates, able to enhance in pig the protection of intestinal mucosa by means of direct and indirect defense actions. The reduced BAX immunostaining observed in O group may be an indicator of enhanced antioxidant action promoted by oregano. The results of this study can be used in further research to identify ways to improve endogenous defence ability, with the aim of reducing antibiotic use and preventing antimicrobial resistance.

The Prophylactic Use of Bovine Colostrum in a Murine Model of TNBS-Induced Colitis.

This study investigated the effects of a short-term administration of bovine colostrum (BC) in a TNBS model of induced colitis. Colitis was induced by TNBS treatment after seven days of BC (BC group, n = 12) or saline (control group, n = 12) administration in mice. Clinical signs, histopathological characteristics, expression levels of Toll-like receptor 4 (TLR4), pro- and anti-inflammatory cytokines, and microbial composition were assessed. BC was well tolerated and did not induce any histological damage or clinical symptoms. After TNBS treatment, the BC group showed a reduction in body weight (BW) loss compared to Control (p < 0.05). Moreover, expression levels of TLR4 (p < 0.01), Interleukin-1ß (IL-1ß; p < 0.001), Interleukin-8 (IL-8; p < 0.001), and Interleukin-10 (IL-10; p < 0.001) were lower in mice administered with BC. Finally, Escherichia coli were higher (p < 0.05), while Enterococci (p < 0.001), Lactobacillus spp. (p < 0.001), and Bifidobacterium spp. (p < 0.05) were lower in Control than BC group. This study confirms that pre-treatment with BC modulates the expression of genes and the count of microbes involved in the etiopathogenesis of colitis.

Beta-lactam resistance in Campylobacter coli and Campylobacter jejuni chicken isolates and the association between blaOXA-61 gene expression and the action of ß-lactamase inhibitors.

The objectives of this work were to evaluate ß-lactamase-mediated ß-lactam resistance in Campylobacter coli and Campylobacter jejuni isolates obtained from broiler chickens, expression of the blaOXA-61 gene in relation to ß-lactamase production, and the possible association between blaOXA-61 gene expression and the action of inhibitors when combined with ß-lactams. All strains were tested by disk diffusion and nitrocefin methods to assess antibiotic susceptibility and ß-lactamase production, respectively. PCR and qPCR amplification were performed to evaluate qualitative and quantitative blaOXA-61 expression. Campylobacter spp. showed a high level of resistance to the most of antimicrobials tested. C. coli strains were ampicillin resistant and blaOXA-61 positive, and 59 out of 60 isolates were positive in the nitrocefin test. Twenty C. jejuni isolates were positive for blaOXA-61 and the nitrocefin test, although two isolates were ampicillin sensitive. Amoxicillin/clavulanic acid and ticarcillin/clavulanic acid do not seem to be active against C. coli, as 73.3 %, and 88.3 % of isolates were resistant to amoxicillin/clavulanic acid and ticarcillin/clavulanic acid, respectively. C. jejuni was not susceptible to amoxicillin/clavulanic acid, with 90 % of the strains showing resistance, whereas ticarcillin associated with clavulanic acid was significantly more efficient than ticarcillin alone (P < 0.01), with 90 % of the strains found to be susceptible. An association between blaOXA-61 expression and amoxicillin/clavulanic acid and ticarcillin/clavulanic acid resistance (P = 0.0001) was seen in C. coli, as well as in C. jejuni for ampicillin/sulbactam (P = 0.0001). Our results suggest that the clavulanic acid only shows an inhibitory effect on C. jejuni when combined with ticarcillin and that the inhibitors action is lower if the blaOXA-61 gene is highly expressed.

Preventive effects of bovine colostrum supplementation in TNBS-induced colitis in mice.

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder for which the current medical therapy is not completely effective. Bovine colostrum (BC) is a biological fluid rich in bioactive molecules that may have beneficial effects on several gastrointestinal disorders. The objectives of this study were to assess the preventive effects of BC supplementation in a mouse model of 2,4,6 trinitrobenzene sulfonic acid (TNBS)-induced colitis using a multidisciplinary approach. Specifically, the following parameters were evaluated: (i) disease activity index (DAI), (ii) histological score, (iii) expression levels of TLR4, anti- and pro-inflammatory cytokines, and (iv) count of some bacterial species of the intestinal microbiota. Mice received a daily suspension of BC (BC group, n = 12) or saline solution (control, CN group, n = 12) for 21 days before the intrarectal inoculation with 1% of TNBS solution. BC was well tolerated and did not induce any histological damage or clinical symptoms. After TNBS treatment, BC group showed a reduction of body weight (BW) loss (P<0.01) and histological score (P<0.05) compared to CN. Moreover, the expression levels of TLR4 (P<0.05), IL-1ß (P<0.001), IL-8 (P<0.001), and IL-10 (P<0.001) were lower in mice administered with BC, while the concentrations of TNF-α did not show any differences between groups. Finally, the supplementation with BC resulted in a differential response to TNBS treatment in the bacterial count. In CN group, E. coli and Enterococci increased (P<0.001), while Anaerobes (P<0.01), Lactobacilli, and Bifidobacteria (P<0.001) reduced. Conversely, no significant changes in bacterial load were found after the inoculation of TNBS in BC pre-treated mice. This study confirms that TNBS-induced colitis model in mice is useful for studying the mechanisms involved in IBD pathogenesis and shows that pre-treatment with BC reduces the intestinal damages and clinical signs of the colitis. Molecular mechanisms and intestinal microflora could be involved in the protective effect of colostrum.

Clinical, virological and epidemiological characterization of an outbreak of Testudinid Herpesvirus 3 in a chelonian captive breeding facility: Lessons learned and first evidence of TeHV3 vertical transmission.

Testudinid herpesviruses (TeHVs) have a worldwide distribution among tortoises. However, information such as risk factors promoting the occurrence or the recrudescence of the associated disease and the mid-term sequelae of an outbreak comprising the extent and dynamic of the viral shedding have been only minimally investigated. Critical management information is also lacking or anecdotal. Furthermore, major aspects of the viral pathogenesis including the likelihood of vertical transmission of the virus are virtually unknown. The present study describes the occurrence and the management of an outbreak of Testudinid herpesvirus genotype 3 (TeHV3) in a large, private collection of chelonians. Clinical, pathological, molecular and serological characterization of the outbreak were carried out. Seventy-five percent of the infected tortoises died. Complementation of molecular and serological testing was a critical point for successful management implementations. A case-control study was performed to analyze possible risk factors associated with the infection. Furthermore, a subgroup of six asymptomatic infected tortoises was monitored for two consecutive seasons after the outbreak: all the infected tortoises were determined to be intermittent shedders, except one, which was a persistent shedder. Post-hibernation was associated with the highest number of shedders. Finally, evidence of the most likely vertical transmission of the virus was obtained for the first time.

Evidence for a primate origin of zoonotic Helicobacter suis colonizing domesticated pigs.

Helicobacter suis is the second most prevalent Helicobacter species in the stomach of humans suffering from gastric disease. This bacterium mainly inhabits the stomach of domesticated pigs, in which it causes gastric disease, but it appears to be absent in wild boars. Interestingly, it also colonizes the stomach of asymptomatic rhesus and cynomolgus monkeys. The origin of modern human-, pig- or non-human primate-associated H. suis strains in these respective host populations was hitherto unknown. Here we show that H. suis in pigs possibly originates from non-human primates. Our data suggest that a host jump from macaques to pigs happened between 100 000 and 15 000 years ago and that pig domestication has had a significant impact on the spread of H. suis in the pig population, from where this pathogen occasionally infects humans. Thus, in contrast to our expectations, H. suis appears to have evolved in its main host in a completely different way than its close relative Helicobacter pylori in humans.

Investigation of the antibiotic resistance and biofilm formation of Staphylococcus pseudintermedius strains isolated from canine pyoderma.

The aim of the present study was to investigate the antibiotic resistance and bio lm formation among a collection of 51 clinical isolates of Staphylococcus pseudintermedius collected from canine pyoderma. All isolates were tested for the susceptibility to a panel of 14 antimicrobial agents by the disk di usion method in Müeller-Hinton agar. Oxacillin resistance was detected by subculture on oxacillin screening agar base. Bio lm formation was investigated by the Microtitre Plate test (MtP) and for some strains by transmission electron microscopy (TEM). Antibiotic resistance pro ling demonstrated that 45/51 S. pseudintermedius isolates had a multi drug resistant (MDR) phenotype, exhibiting simultaneous resistance to at least 3 antibiotics categories; whereas 6 isolates showed a non-MDR phenotype. Thirty strains (59%) were resistant in oxacillin resistant screening agar, the same strains were also positive for mecA by PCR assay. All S. pseudintermedius isolates showed bio lm production by MtP method. Seventeen out of 51 isolates were classi ed as weakly adherent, 26 as moderately adherent, and 8 as strongly adherent. Moreover, no di erence in bio lm formation between meticillin-resistant S. pseudintermedius (MRSP) and meticillin-suscebtible S. pseudintermedius (MSSP) (P value > 0.05) was noted. The antimicrobial resistance mechanisms and bio lm formation could explain the di culty in treating S. pseudintermedius canine infections, chemotherapeutic failure, and consequently persistent infections.

Potential benefits of colostrum in gastrointestinal diseases.

This paper reviews the composition of colostrum and the potential preventive and therapeutic use of this "first milk" for treating various gastrointestinal disorders in humans. Colostrum is a complex biological liquid that is richer in antimicrobial peptides, immune-regulating compounds and growth factors than the subsequent mature milk. The main functions of colostrum are to provide essential nutritional components, strengthen the natural defense system, modulate immune response, balance intestinal microbiota and enhance the growth and repair of several tissues. Several studies and clinical trials carried out both in vitro and in vivo on humans and animals suggest the clinical benefits of bovine colostrum (BC) supplementation in gastro-intestinal diseases. Despite the encouraging results, further well-designed studies are required in order to confirm these effects, the dose and duration of treatment. Colostrum is safe since there are no contraindications regarding high dose levels and few side effects of clinical relevance have been reported. In conclusion, in the near future, colostrum-based supplements may play a complementary role to synthetic drugs in the prevention and treatment of various gastrointestinal disorders.

Phenotypic and genotypic characterization of canine pyoderma isolates of Staphylococcus pseudintermedius for biofilm formation.

Biofilm-forming ability is increasingly being recognized as an important virulence factor in several Staphylococcus species. This study evaluated the biofilm-forming ability of sixty canine derived clinical isolates of S. pseudintermedius, using three phenotypic methods, microtiter plate test (MtP), Congo red agar method (CRA) and tube adherence test, and the presence and impact of biofilm-associated genes (icaA and icaD). The results showed that icaA and icaD genes were detected concomitantly in 55 (91.7%) of 60 isolates. A majority (88.3%) of the strains screened had matching results by the tube adherence test, MtP and PCR analysis. Better agreement (95%) was found between the PCR-based analysis and the CRA. Results of the icaA and icaD gene PCRs showed good agreement with CRA results, with a kappa of 0.7. Comparing the phenotypic methods, the statistical analysis showed that the agreement among the phenotypical tests using categorical data was generally good. Considering two classes (biofilm producer and biofilm non-producer), the percentage of matching results between the CRA method and the tube adherence test and between the CRA method and the MtP was 93.3%. A concordance of 100% was revealed between the MtP and the tube adherence test. The results indicate a high prevalence of the ica genes within S. pseudintermedius isolates, and their presence is associated with in vitro formation of a biofilm. A combination of phenotypic and genotypic tests is recommended for investigating biofilm formation in S. pseudintermedius.

Detection of Equid herpesvirus type 2 and 5 DNA in uterine flushings of mares with reproductive disorders.

In recent years, there has been increasing evidence of the potential pathogenic significance of equine gammaherpesviruses in the horse. In humans, cattle and mice, gammaherpesviruses have already been associated with uterine infection. The aim of the present study was to investigate the presence of gammaherpesviruses in uterine flushings of mares with reproductive problems and to evaluate if there was a possible statistical association with clinical and laboratory findings in these cases. A total of 80 uterine flushings were collected from 61 mares with different reproductive problems and these were tested for equine herpesviruses (EHV) 1-5 by PCR. In the case of each mare in the study, the age, history of infertility, presence of anatomical defects in the reproductive tract, presence of systemic or local disease at time of sampling, phase in the oestrous cycle, post-partum interval, nature of uterine lavage performed (low versus large volume lavage), cytological and bacteriological examination results from the uterine flushing, and PCR herpesvirus results were recorded. Univariate analysis and multivariable logistic regression models were used to identify possible statistical associations and risk factors. Nine out of 61 mares (14.7%) had EHV-5 DNA in their uterine flushings. Co-infections with EHV-1 and EHV-2 were present in two cases. Of all the variables analyzed, only the cytological examination findings were associated with EHV-5 PCR positive results, both on univariate and multivariable analysis, especially in cases with an inflammation score of 3. It is postulated that presence of EHV-5 infection in the non-pregnant uterus may have a role to play in reproductive dysfunction and have a negative consequence on the pregnant uterus. Additional studies involving both healthy mares and mares with reproductive problems need to be performed, however, to elucidate whatever role equine gammaherpesviruses may play in the reproductive tract. This would be very worthwhile, since reproductive problems can have a significant impact on the equine breeding industry. Gaining a greater understanding of its causes could lead to new approaches for prevention and treatment.

A case of Candida guilliermondii abortion in an Arab mare.

Ascending infections of equine uterus frequently result in placentitis and abortions; most of these infections are bacterial and are less commonly due to fungi. This report describes an abortion case in an Arab mare due to Candida guilliermondii that was diagnosed via cytological, histological, cultural and biomolecular assays. The histological lesions found were severe necrotizing placentitis associated with fetal pneumonia. To our knowledge this is the first case of C. guilliermondii abortion reported in equine species.

Is the horse a reservoir or an indicator of Coxiella burnetii infection? Systematic review and biomolecular investigation.

The role of the horse in Coxiella burnetii infection has not been defined. Accordingly, a twofold approach was taken to further our knowledge on this topic: (1) conduct a systematic review of the literature to establish available evidence of C. burnetii infection in the horse; (2) undertake a biomolecular investigation of 122 cases of equine abortion, stillbirth and neonatal foal death, for the presence of C. burnetii using a PCR test targeting the IS1111 gene of C. burnetii. A review of the literature turned up seven studies that identified C. burnetii DNA in equine specimens, especially aborted fetuses, while an additional 34 studies sought to determine seroprevalence of the infection in the horse. A meta-analytical approach was taken to calculate a pooled mean seroprevalence in equines based on published studies. A seroprevalence of 15.8% (95% confidence interval: 9.6-23.0%) was obtained. This figure is comparable to those previously reported in other species, especially ruminants. None of the 122 cases of equine abortion, stillbirth or neonatal foal death were positive for C. burnetii DNA. C. burnetii has rarely been looked for in equine specimens in previous studies. Cases of equine abortion should be comprehensively investigated to assess the risk of abortion in a pregnant mare infected with C. burnetii. Consideration should also be given to the possible role of the horse as a source of the organism for other animal species including humans.

Role of equine herpesviruses as co-infecting agents in cases of abortion, placental disease and neonatal foal mortality.

Herpesviral infections frequently occur in horses. The objective of this study was to investigate the possible association of equine herpesviruses (EHV-1, EHV-2, EHV-3, EHV-4, EHV-5) with other causes of abortion, neonatal mortality or placental disorder. Sixty-seven abortions, 22 stillbirths, 14 cases of neonatal foal mortality and 3 cases of placental disease were investigated for infectious and non-infectious causes. Type-specific nested PCR assays and virus isolation were performed to detect EHV infections. A cause of fetal loss or placental disease was reached in 68 out 116 (58.7%) cases. Twenty-seven cases were positive for EHV, and 22/27 (81.5%) were positive for EHV-1 (16 neuropathogenic and 6 non-neuropathogenic strains), 4 (14.8%) for EHV-2 and 3 (11.1%) for EHV-5. The association between EHV infections and other etiological agents was statistically significant (two sided P = 0.002). The odds ratio of EHV DNA associated with other diagnoses, especially with bacterial infection and premature placental separation, was 10.88 (95% confidence interval: 2.15-55.16). EHV-1 was the main viral cause of pregnancy loss in this study, also associated with other etiological agents, including EHV-2 and EHV-5. The latter viruses in particular need to be more fully investigated to elucidate what role either or both may play as co-infecting agents with other established infectious causes of reproductive disease.

Pulmonary rhodococcosis in a cat.

Feline Rhodococcus equi infection is rare, despite the bacteria is widespread in the environment. R equi infection is typically observed in equine species but the infection has also been reported in dogs, cats and other domestic animals. There are a few reports regarding pulmonary R equi infection in cats and the disease appears to be limited to the skin and the subcutaneous tissue. This report describes the pathological, microbiological and the virulence features associated with an acute necrosuppurative pneumonia in a cat. To the best of our knowledge, this is the first report of feline pulmonary R equi infection in Italy.

Detection of Helicobacter spp. in gastric, fecal and saliva samples from swine affected by gastric ulceration.

The aim of this study was to evaluate the presence of Helicobacter (H.) spp. in swine affected by gastric ulceration. Stomachs from 400 regularly slaughtered swine were subjected to gross pathological examination to evaluate the presence of gastric ulcers. Sixty-five samples collected from ulcerated pars esophagea and 15 samples from non-ulcerated pyloric portions were submitted to histopathological and molecular analyses, to detect Helicobacter spp., H. suis and H. pylori by PCR. Feces and saliva swabs were also collected from 25 animals in order to detect in vivo the presence of Helicobacter spp.. Gastric ulcers were detected in 373 cases (93%). The presence of ulcers in association with inflammatory processes was further confirmed by histological examination. Forty-nine percent (32/65) of the ulcerated esophageal portions as well as 53% (8/15) of the non-ulcerated pyloric portions were positive for Helicobacter spp. by PCR. The Helicobacter spp. positive samples were also positive for H. suis, while H. pylori was not detected. These results were confirmed by restriction enzyme analysis. With regard to feces and saliva samples, 15/25 (60%) and 16/25 (64%) were positive for Helicobacter spp. PCR, respectively but all were negative in H. suis and H. pylori specific PCR.

Characterization of genes encoding virulence determinants and toxins in Staphylococcus aureus from bovine milk in Central Italy.

The aim of this study was to evaluate the genotypic characteristics of Staphylococcus aureus isolates (n=170) from bovine milk collected from seven dairy farms in Italy. On the basis of cultural and biochemical properties and by amplification of the 23S rRNA specific to S. aureus, all isolates were identified as S. aureus. To genotypically characterize S. aureus isolates, genes encoding virulence determinants (nuc, clfA, spa-IgG-binding, spa-X-region, fnbA and fnbB, cap5 and cap8) and staphylococcal enterotoxins (sea, seb, sec, sed, see, seg, seh, sei, sej) were investigated using a PCR technique. The results showed that the isolates of S. aureus in each farm had the same genotypic characteristics, while the isolates genotipically differed between the different farms. The present study might help to understand the distribution of prevalent S. aureus strains in dairy farms.

Hafnia alvei infection in pullets in Italy.

This paper describes an outbreak of disease caused by Hafnia alvei in pullets. Cloudy swelling and the fatty degeneration of liver associated with splenic lymphocytic depletion were the most preminent lesions. The organism was identified by biochemical tests and by a Hafnia-specific bacteriophage test. Laying hens and pullets were infected experimentally with the organism by the oral and intraperitoneal route, and the clinical and pathological effects were similar to those observed in naturally infected subjects. The use of more sensitive diagnostic tests is suggested to avoid the possibility of a misdiagnosis due to similarities between this organism and Salmonella species.