Humoral responses in cattle to commercial vaccines containing Clostridium perfringens epsilon toxoid and C. botulinum types C and D toxoids last less than a-year.

The aim of this study was to evaluate the titers of neutralizing antibodies in cattle inoculated with multivalent commercial clostridial vaccines containing C. botulinum type C (BoNTC), C. botulinum type D (BoNTD), and C. perfringens epsilon (ETX) toxoids for a period of one year. Cattle (Bos taurus), aged 4-6 months and not previously immunized, were vaccinated under four different protocols at days 0 and 30 and followed over one year. Individual serum titration was performed by a serum neutralization test in mice or in MDCK cells. The number of animals with detectable neutralizing antibodies ranged from 40.6% to 78.1%, but only 12.5% of animals showed neutralizing antibodies against all tested antigens. Neutralizing antibodies were found only until 60 days for ETX, 120 days for BoNTC, and 180 days for BoNTD. The absence of detectable neutralizing antibodies against the three antigens before 360 days, suggests that cattle remained unprotected for a long period before the recommended booster vaccination.

Molecular epidemiology of Clostridioides (previously Clostridium) difficile isolates from a university hospital in Minas Gerais, Brazil.

The molecular epidemiology of 38 non-duplicate toxigenic Clostridioides (previously Clostridium) difficile isolates from inpatients from a hospital in Brazil during a 6-year period (2012-2017) were investigated by multilocus sequence typing (MLST) and ribotyping. These isolates were classified into 20 sequence types (ST), six (30%) of which were novel, revealing a high diversity in a single hospital. Classic hypervirulent strains ST1/RT027 and ST11/RT078 were not identified, while ST42 (almost all RT106) was the most common type, being detected in 11 (28.9%) strains. Noteworthy, six (15.8%) isolates were classified into five STs from clade 2, four of which were new ST and RT. Our study suggests that possible hypervirulent strains other than ST1/RT027 might be inadvertently circulating in Brazilian hospitals and highlights the importance of permanent surveillance on circulating strains in a national scale.

The non-toxigenic strain of Clostridioides difficile Z31 can prevent infection by C. difficile in experimental model piglets.

One of the main challenges associated with Clostridioides difficile infection (CDI) in humans and domestic animals is the lack of an effective preventive strategy. One strategy with promising results is the oral administration of non-toxigenic strains of C. difficile (NTCD). Recently, Z31, a NTCD strain isolated from a healthy dog, showed promising results to prevent CDI in hamsters. Thus, the present study aimed to evaluate the capacity of Z31 to prevent CDI in piglets using an experimental model. Twenty neonatal piglets were randomly distributed in three groups: G1 - 106 spores of Z31 followed by 107 spores of a toxigenic C. difficile strain (n = 7), G2 (positive control) - 107 spores of a toxigenic C. difficile strain (n = 7), and G3 (negative control) - no biological inoculum (n = 6). All animals were kept in individual insulators and observed for 60 h. Data regarding clinical signs, macro and microscopic lesions, toxigenic culture of C. difficile, and detection of A/B toxins in the feces were evaluated. All evaluated parameters were significantly lower in animals that received Z31 compared to the positive control. Thus, oral administration of Z31 was able to prevent CDI in piglets in an experimental model.

Clinical epidemiology of Clostridium difficile infection among hospitalized patients with antibiotic-associated diarrhea in a university hospital of Brazil.

A cohort of 110 adult individuals was analyzed to compare clinical characteristics of hospitalized patients who received antibiotics and developed Clostridium difficile infection (CDI) with those who received antibiotics and did not develop the disease in a university Hospital in Brazil. CDI was diagnosed by toxigenic culture and C. difficile isolates were characterized by PCR ribotyping. Stool samples were also screened for Clostridium perfringens, methicillin-resistant Staphylococcus aureus (MRSA) and Klebsiella oxytoca. The prevalence of CDI among patients with AAD was 31.8%. C. difficile diarrhea was significantly associated with the severity of underlying comorbidities at admission (OR = 1.21; 95% CI, 1.04-1.40) and with the number of antibiotics used during hospitalization (OR = 1.43; 95% CI, 1.07-1.92). Diabetes mellitus was markedly associated with a higher risk of death in patients with AAD (OR = 6.38; 95% CI, 1.33-30.7). PCR ribotypes 014/020 and 106 (20.6% each) were the most common among the isolates. Binary toxin-encoding gene (cdtB) was detected in six samples, but previously described hypervirulent ribotypes 027 and 078 were not found. K. oxytoca and enterotoxigenic C. perfringens were not detected, while only one patient (0.9%) was positive for MRSA. Our results indicate that comorbidity severity and the number of antibiotics used during hospitalization are strong independent predictors of nosocomial C. difficile diarrhea. Diabetes was associated with a higher mortality among patients with AAD. A huge diversity of C. difficile ribotypes was observed in our study, although classical hypervirulent strains were not observed.

Acute necrotizing colitis with pneumatosis intestinalis in an Amazonian manatee calf.

On 25 January 2014, a 1 mo old female Amazonian manatee Trichechus inunguis calf weighing 12 kg was rescued by air transport in Guajará, Brazil, and transferred to Mamirauá Institute's Community-based Amazonian Manatee Rehabilitation Center. The calf presented piercing/cutting lesions on the back, neck, and head, in addition to dehydration and intermittent involuntary buoyancy. X-ray analysis revealed a large amount of gases in the gastrointestinal tract. Daily procedures included wound cleaning and dressing, clinical and laboratory monitoring, treatment for intestinal tympanism, and artificial feeding. Adaptation to the nursing formula included 2 kinds of whole milk. Up to 20 d post-rescue the calf presented appetite, was active, and gained weight progressively. Past this period the calf started losing weight and presented constant involuntary buoyancy and died after 41 d in rehabilitation. The major findings at necropsy were pneumatosis intestinalis in cecum and colon, pulmonary edema, and hepatomegaly. The microscopic examination revealed pyogranulomatous and necrohemohrragic colitis with multinucleated giant cells, acute multifocal lymphadenitis with lymphoid depletion in cortical and paramedullary regions of mesenteric lymph nodes, and diffuse severe acinar atrophy of the pancreas. Anaerobic cultures of fragments of cecum and colon revealed colonies genotyped as Clostridium perfringens type A. We speculate that compromised immunity, thermoregulatory failure, and intolerance to artificial diet may have been contributing factors to the infection, leading to enterotoxemia and death.

Antimicrobial susceptibility of Clostridium perfringens isolated from piglets with or without diarrhea in Brazil.

The minimum inhibitory concentration (MIC) was determined for 13 antibiotics against Clostridium perfringens isolated from Brazilian piglets. The collection of isolates was performed in June to October 2010. All isolates were susceptible to amoxicillin and ceftiofur, whereas most were resistant to tetracycline and lincomycin. Avilamycin and narasin were more effective against isolates from non-diarrheic than from diarrheic piglets. The other antimicrobials were less active in need of high concentrations to inhibit the growth of the C. perfringens type A. These results suggest the need for further studies evaluating molecular factors related to the antimicrobial resistance of C. perfringens.