A new predilection site of Mycoplasma bovis: Postsurgical seromas in beef cattle

Bacterial Contamination of the Surgical Site at the Time of Elective Caesarean Section in Belgian Blue Cows-Part 2: Identified by 16Sr DNA Amplicon Sequencing

This study aimed to describe the bacterial composition of the surgical site during elective caesarean sections (CSs) using the 16Sr DNA amplicon sequencing performed in parallel to bacterial culture. The study involved 13 Belgian blue cows of a previous dataset of 76 animals. Bacteriology was performed on swabs sampled from visceral and parietal peritoneum during the CS. Amplicon sequencing was performed in six samples chosen randomly among the swabs positive for bacteriology and seven among the culture-negative swabs. A total of 2542 bacterial operational taxonomic units belonging to 567 genera were identified. The most often identified genus and species were Mycoplasma (44%) and Mycoplasma wenyonii (36%), respectively. Results showed no difference in microbiota composition between the culture-positive and -negative samples. However, a difference was observed between the bacteriology and amplicon sequencing results. Indeed, seven out of nine cultured strains were not identified by amplicon sequencing in the samples in which they were cultured. In contrast to bacteriology, amplicon sequencing unveiled the presence of bacterial DNA in all elective CSs. The most identified DNA is most likely derived from the haematogenous spread of bacteria to the surgical site. Furthermore, the cultured bacteria were not the dominant species in the sample from which they were cultured.

Blood Inflammatory, Hydro-Electrolytes and Acid-Base Changes in Belgian Blue Cows Developing Parietal Fibrinous Peritonitis or Generalised Peritonitis after Caesarean Section

This study aimed to describe the inflammation, hydro-electrolyte and acid-base imbalances caused by generalised peritonitis (GP) and parietal fibrinous peritonitis (PFP) after caesarean section. After clinical examination, blood was sampled from 11 cows with PFP, 30 with GP and 14 healthy cows. Serum and plasma refractometry and glutaraldehyde tests were used to evaluate the inflammation level, while hydro-electrolytes and acid-base parameters were assessed using an EPOC® device. In addition to clinical signs of dehydration (>10%), blood analysis showed a high fibrinogen concentration (PFP: 8.64 ± 8.82 g/L; GP: 7.83 ± 2.45 g/L) and fast glutaraldehyde coagulation (<3 min) indicative of severe inflammation in both diseases compared to the control group (p < 0.05). Moreover, a severe decrease in electrolytes concentration (Na+: 126.93 ± 5.79 mmol/L; K+: 3.7 ± 1.3 mmol/L; Ca++: 0.89 ± 0.12 mmol/L; Cl−: 82.38 ± 6.45 mmol/L) and a significant increase in bicarbonate (30.87 ± 8.16 mmol/L), base excess (5.71 ± 7.42 mmol/l), L-lactate (8.1 ± 4.85 mmol/L) and creatinine (3.53 ± 2.30 mg/dL) were observed in cows with GP compared to the control group (p < 0.05). In contrast, few major perturbations were noticed in PFP, where only K+ (3.64 ± 0.25 mmol/L) and Ca++ (1.06 ± 0.09 mmol/L) were significantly modified (p < 0.05). In conclusion, a high dehydration and severe inflammation are induced by PFP and GP. Nevertheless, GP causes more electrolytes and acid-base disturbances than PFP.

Antimicrobial Susceptibility Profile of Several Bacteria Species Identified in the Peritoneal Exudate of Cows Affected by Parietal Fibrinous Peritonitis after Caesarean Section

The aim of this study was to identify the species and antimicrobial susceptibility of bacteria involved in parietal fibrinous peritonitis (PFP). We studied 156 peritoneal fluid samples from cows presenting PFP after caesarean section. Bacteria were cultured in selective media and their antimicrobial susceptibility was tested by disk diffusion assay. Bacteria were isolated in the majority (129/156; 83%) of samples. The majority (82/129; 63%) of positive samples contained one dominant species, while two or more species were cultured in 47/129 (36%) samples. Trueperella pyogenes (T. Pyogenes) (107 strains) was the most identified species, followed by Escherichia coli (E. coli) (38 strains), Proteus mirabilis (P. mirabilis) (6 strains), and Clostridium perfringens (C. perfringens) (6 strains). Several other species were sporadically identified. Antimicrobial susceptibility was tested in 59/185 strains, predominantly E. coli (38 strains) and P. mirabilis (6 strains). Antibiotic resistance, including resistance to molecules of critical importance, was commonly observed; strains were classified as weakly drug resistant (22/59; 37%), multidrug resistant (24/59; 41%), extensively drug resistant (12/59; 20%), or pan-drug resistant (1/59; 2%). In conclusion, extensive antibiotic resistance in the isolated germs might contribute to treatment failure. Ideally, antimicrobial therapy of PFP should be based upon bacterial culture and susceptibility testing.

Parietal fibrinous peritonitis in cattle: A literature review

BACKGROUND

Parietal fibrinous peritonitis (PFP) is a complication of laparotomy in cattle, consisting of fluid and fibrin accumulation within a fibrous capsule between the parietal peritoneum and the abdominal muscles. Since scientific information on PFP is scarce, we aim to collect available information to help practitioners in its diagnosis and treatment, and to formulate research perspectives.

METHODS

PubMed and GoogleScholar databases were scanned using "cattle" or "bovine", and one of the following keywords: "seroma", "parietal fibrinous peritonitis", "retroperitoneal abscess", or "wound infection".

RESULTS

Although scientific information is often anecdotal, two recent larger studies shed more light on PFP symptoms, diagnosis and treatment. Symptoms vary according to the cavity's localisation and size, and include anorexia, weight loss and an inflammatory status. Rectal palpation is strongly indicative, but the definitive diagnosis is made by ultrasound. Trueperella pyogenes and Escherichia coli are frequently isolated germs, although it remains unclear whether they are primary or secondary agents. Good survival rates were reported after surgical drainage.

CONCLUSION

Although the diagnosis and treatment seem clear, the exact pathogenesis of PFP should be the focus of ongoing research. This can be achieved by epidemiological data analysis focusing on risk factors like surgery technique, housing and ration.

Multi-locus sequence typing of Mycoplasma bovis to assess its genetic diversity from 2009 to 2018 in Ningxia Hui Autonomous Region, China

Background

Mycoplasma bovis (M. bovis) is a highly contagious cattle pathogen spreading worldwide and especially in Ningxia Hui Autonomous Region in China.

Results

Two types of ST, ST10and ST134, were identified in Ningxia Hui Autonomous Region. Thirty-seven strains belonged to ST10 and 28 strains belonged to ST134. ST134 was a new ST and first found in 2009 and was only widely distributed in Ningxia Hui Autonomous Region at present. The M. bovis ST10 was widely spread in many provinces in China and was widespread in Ningxia Hui Autonomous Region since 2010. It is speculated that the prevalence of M. bovis ST10 in Ningxia Hui Autonomous Region began in 2010.

Conclusions

This study is the first report on the genetic diversity of M. bovis from 2009 to 2018 in Ningxia Hui Autonomous Region and provides the epidemiological information. These results may help further our understanding of the evolution of M. bovis and provide information that may be useful for the development of novel vaccines.

Phylogenomic analysis of Mycoplasma bovis from Belgian veal, dairy and beef herds

M. bovis is one of the leading causes of respiratory disease and antimicrobial use in cattle. The pathogen is widespread in different cattle industries worldwide, but highest prevalence is found in the veal industry. Knowledge on M. bovis strain distribution over the dairy, beef and veal industries is crucial for the design of effective control and prevention programs, but currently undocumented. Therefore, the present study evaluated the molecular epidemiology and genetic relatedness of M. bovis isolates obtained from Belgian beef, dairy and veal farms, and how these relate to M. bovis strains obtained worldwide. Full genomes of one hundred Belgian M. bovis isolates collected over a 5-year period (2014–2019), obtained from 27 dairy, 38 beef and 29 veal farms, were sequenced by long-read nanopore sequencing. Consensus sequences were used to generate a phylogenetic tree in order to associate genetic clusters with cattle sector, geographical area and year of isolation. The phylogenetic analysis of the Belgian M. bovis isolates resulted in 5 major clusters and 1 outlier. No sector-specific M. bovis clustering was identified. On a world scale, Belgian isolates clustered with Israeli, European and American strains. Different M. bovis clusters circulated for at least 1.5 consecutive years throughout the country, affecting all observed industries. Therefore, the high prevalence in the veal industry is more likely the consequence of frequent purchase from the dairy and beef industry, than that a reservoir of veal specific strains on farm would exist. These results emphasize the importance of biosecurity in M. bovis control and prevention.

Infectious Agents Identified by Real-Time PCR, Serology and Bacteriology in Blood and Peritoneal Exudate Samples of Cows Affected by Parietal Fibrinous Peritonitis after Caesarean Section

The aim of this study was to identify the pathogens potentially involved in parietal fibrinous peritonitis (PFP). PFP is a complication of laparotomy in cattle, characterized by an accumulation of exudate inside a fibrinous capsule. We have studied 72 cases of PFP in Belgian blue cows, confirmed by a standard diagnostic protocol. Blood was collected to evaluate the presence of antibodies for Mycoplasma bovis(M. bovis), Coxiella burnetii(C. burnetii) and Bovine Herpesvirus 4(BoHV4) by enzyme-linked immunosorbent assays. Peritoneal exudate was obtained from the PFP cavity to perform bacteriological culture, and to identify the DNA of M. bovis, C. burnetii and BoHV4 using real time polymerase chain reaction (qPCR). Bacteriological culture was positive in most peritoneal samples (59/72); Trueperella pyogenes (T. pyogenes) (51/72) and Escherichia coli (E. coli) (20/72) were the most frequently identified. For BoHV4, the majority of cows showed positive serology and qPCR (56/72 and 49/72, respectively). Contrariwise, M. bovis (17/72 and 6/72, respectively) and C. burnetii (15/72 and 6/72, respectively) were less frequently detected (p < 0.0001). Our study proves that PFP can no longer be qualified as a sterile inflammation. Moreover, we herein describe the first identification of BoHV4 and C. burnetii in cows affected by PFP.

Comparison between generalised peritonitis and parietal fibrinous peritonitis in cows after caesarean section

BACKGROUND

Parietal fibrinous peritonitis (PFP) and generalised peritonitis (GP) are two postoperative complications in cows, characterised by fluid and fibrin accumulation throughout the peritoneum (GP) or in an encapsulated cavity (PFP). Unlike GP, PFP is scarcely documented.

METHODS

Twenty-one GP cases and 12 PFP cases were confirmed by ultrasound in cows referred to the Veterinary Clinic (Liège University) for complications after caesarean section. All cows underwent a standardised examination protocol. Blood samples were analysed for metabolic and inflammatory markers. Bacteriology was performed on peritoneal fluid samples. Treatment consisted of surgical drainage of the abdominal cavity (GP) or the encapsulated cavity (PFP). Variables concerning anamnesis, clinical findings and treatment outcomes were compared.

RESULTS

Perioperative complications had occurred in 9/21 GP cows but 0/12 PFP cows (P<0.05). Biochemical analysis indicated pronounced inflammation and did not differ between groups. Peritoneal fluid samples of both groups were contaminated and contained similar bacteria (Trueperella pyogenes and Escherichia coli). While 11/12 PFP cows were discharged, all patients with GP died or were euthanased (P<0.05).

CONCLUSIONS

We hypothesise that PFP and GP are two different manifestations of perioperative peritoneal contamination. The severity and spread of the contamination determine the clinical presentation and the prognosis.

Pathogenesis and Virulence of Mycoplasma bovis

Mycoplasma bovis is an important component of the bovine respiratory disease complex and recent reports identified that other species are also affected by M bovis. Control of the disease caused by M bovis has been unsuccessful owing to many factors, including the capacity of M bovis to evade and modulate the immune system of the host; the lack of known virulence factors; the absence of a cell wall, which renders antibiotics targeting cell-wall synthesis unusable; and the failure of vaccines to control disease on the field. The current knowledge on virulence and pathogenesis is presented in this review.

Gap analysis of Mycoplasma bovis disease, diagnosis and control: An aid to identify future development requirements

There is a worldwide problem of disease caused by Mycoplasma (M.) bovis in cattle; it has a significant detrimental economic and animal welfare impact on cattle rearing. Infection can manifest as a plethora of clinical signs including mastitis, pneumonia, arthritis, keratoconjunctivitis, otitis media and genital disorders that may result in infertility and abortion. Current diagnosis and control information are reviewed and analysed to identify gaps in knowledge of the causative organism in respect of the disease pathology, diagnosis and control methods. The main considerations are as follows: no vaccines are commercially available; antimicrobial resistance is increasing; diagnostic and antimicrobial sensitivity testing needs to be improved; and a pen-side test would facilitate more rapid diagnosis and implementation of treatment with antimicrobials. More data on host susceptibility, stress factors, immune response and infectious dose levels are required. The impact of asymptomatic carriers, M. bovis survival in the environment and the role of wildlife in transmitting the disease also needs investigation. To facilitate development of vaccines, further analysis of more M. bovis genomes, its pathogenic mechanisms, including variable surface proteins, is required, along with reproducible disease models.

Short communication: Effect of freezer storage time and thawing method on the recovery of Mycoplasma bovis from bovine colostrum

Mycoplasma bovis is an important cause of mastitis in dairy cattle, and pneumonia, arthritis, and otitis in calves. Milk and colostrum are considered important sources of infection for calves. knowledge on the effect of on-farm freezing (-18°C) and thawing methods on the recovery of M. bovis from colostrum samples is missing. In this study, 2 separate experiments were performed. The first experiment consisted of a longitudinal study examining the survival [as measured by log(10) reduction] of 2 M. bovis strains in frozen colostrum over 14 wk. The second experiment examined the effect of different thawing temperatures (45 and 20°C), thawing frequencies (once or twice), and initial colostrum titer (10⁴ or 10⁶ cfu/mL) on M. bovis survival. A single freeze-thaw cycle led to an approximate 1 log reduction of M. bovis titer, independent of the thawing temperature. Freezing for 14 wk did not significantly further reduce the titer of bacteria compared with freezing for 2 wk. A second freeze-thaw cycle further reduced the M. bovis count by approximately 0.5 log compared with a single freeze-thaw cycle. Thawing temperature and initial bacterial concentration did not significantly affect M. bovis reduction. In conclusion, storage of colostrum samples in the freezer at -18°C during epidemiological studies, herd monitoring, or test and cull programs will probably have little influence on qualitative bacteriological test results for M. bovis. The epidemiological or clinical relevance of an approximate 1 log reduction of M. bovis in colostrum is currently unclear.

Status of the development of a vaccine against Mycoplasma bovis

Mycoplasma bovis is an important pathogen of cattle and, despite numerous efforts an effective vaccine for control of the disease it causes remains elusive. Although we now know more about the biology of this pathogen, information is lacking about appropriate protective antigens, the type of immune response that confers protection and adjuvants selection. The use of conserved recombinant proteins, selected using in silico approaches, as components of a vaccine may be a better choice over bacterin-based vaccines due to the limited protection afforded by them and adverse reactions caused by them. More studies are needed on the characterization of host-pathogen interactions and to elucidate M. bovis products modulating these interactions. These products could be the basis for development of vaccines to control M. bovis infections in dairy farms and feedlots.