State-of-the-art MALDI-TOF Technology at WVDL Identifies Emerging Bacterial Pathogens
WVDL Microbiologist Maureen Peterson
The Microbiology Section at WVDL has been using a MALDI-TOF machine to rapidly and accurately identify bacterial pathogens for several months now, starting in the spring of 2014. MALDI-TOF is a matrix-assisted laser desorption ionization/mass spectrometry machine that identifies bacteria based on their unique signature. Along with the usual pathogens the MALDI-TOF unit has been identifying several emerging bacterial mastitis pathogens, such as Lactococcus garvieae, which is aiding bovine veterinarians to improve milk quality and profitability on Wisconsin Dairies.
Contact the WVDL if you receive a culture result with a microbial species that is new to your practice for more information.
The following is a recent article from Veterinary Microbiology highlighting the MALDI-TOF’s ability to speciate hard to identify Corynebacterium spp.
Corynebacterium species (spp.) are among the most frequently isolated pathogens associated with subclinical mastitis in dairy cows. However, simple, fast, and reliable methods for the identification of species of the genus Corynebacterium are not currently available. This study aimed to evaluate the usefulness of matrix-assisted laser desorption ionization/mass spectrometry (MALDI-TOF MS) for identifying Corynebacterium spp. isolated from the mammary glands of dairy cows. Corynebacterium spp. were isolated from milk samples via microbiological culture (n=180) and were analyzed by MALDI-TOF MS and 16S rRNA gene sequencing. Using MALDI-TOF MS methodology, 161 Corynebacterium spp. isolates (89.4%) were correctly identified at the species level, whereas 12 isolates (6.7%) were identified at the genus level. Most isolates that were identified at the species level with 16 S rRNA gene sequencing were identified as Corynebacterium bovis (n=156; 86.7%) were also identified as C. bovis with MALDI-TOF MS. Five Corynebacterium spp. isolates (2.8%) were not correctly identified at the species level with MALDI-TOF MS and 2 isolates (1.1%) were considered unidentified because despite having MALDI-TOF MS scores >2, only the genus level was correctly identified. Therefore, MALDI-TOF MS could serve as an alternative method for species-level diagnoses of bovine intramammary infections caused by Corynebacterium spp.
Did you know that the WVDL tests for Chronic Wasting Disease (CWD) in wild deer from Wisconsin and from five other states and farmed deer from 13 other states? The TSE (transmissible spongiform encephalopathy) laboratory at the WVDL was formed in 2002 in response to the discovery of CWD in Wisconsin. In 2013, WVDL tested 6,592 CWD samples for the Wisconsin Department of Natural Resources (356 were test positive).
In addition to CWD, other types of TSE such as bovine spongiform encephalopathy (BSE/mad cow disease) and scrapie (a disease of sheep) are tested at WVDL as part of national surveillance programs.
As mentioned previously, the WVDL does CWD testing for many states around the country, including Arkansas. The Razorback state recently posted this article regarding CWD in its state deer population.
EHV-1 can cause respiratory disease, abortions and occasionally neurological disease in horses as well. There are strain variants, one of which is more strongly associated with neurologic disease (neuroparalytic strain); however at least 25% of horses with neurologic disease do not have the neurologic strain.
Recently, horses in Minnesota and Wisconsin have developed hind limb paralysis and have tested positive by real time PCR for EHV-1. The WVDL offers a real time PCR for EHV-1, and it has the capability to differentiate between the wild type and the neurotropic strains of EHV-1. Veterinarians should submit nasal swabs that are placed in viral transport media or in 1 ml of sterile saline from acutely affected horses to the WVDL for testing. Samples should be sent over-night to the Madison laboratory with a sufficient number of ice-packs to keep the samples cold during shipment to the laboratory. Do not use cotton tipped swabs or swabs with wooden shafts because they contain bleach which may interfere with the PCR assay and cause a false negative test. Results are available within 1-3 business days after receipt of the samples. Veterinarians can order swabs and viral transport media from the WVDL. Please call 1-800-608-8387 and ask for the supply room.
BAPA IS OFFICIAL BRUCELLOSIS SCREENING TEST AT WVDL
Rap Test No Longer Offered
The BAPA test is now the official Brucellosis screening test used at the WVDL. The RAP test will no longer be offered. Discontinuation of the RAP at the WVDL should not pose any difficulty for our submitters. Use of the BAPA will meet all the requirements for an official Brucellosis screening test for B abortis, B suis, and B mellitensis. Please note that the BAPA test is not suitable for serologic screening for Brucella ovis or B canis. Testing for these two organisms requires alternate tests.
Brucellosis screening can be requested by using the Serology & Multiple Test Submission Form (available on the WVDL website: www.wvdl.wisc.edu). Mark the box selecting “Bruc/BAPA.” Additional information on the BAPA test is available on our website.
Please note that the Standard Tube Test (STT) and Standard Plate Test are (SPT) are not screening tests for Brucellosis. These tests should only be requested if they are a specified test requirement.
Please contact us if you have questions or concerns.
Dr. Bell Travels to India for Veterinary Pathology Congress
Dr. Bell presents an overview of her trip to the staff at WVDL.
Dr. Cindy Bell of WVDL, with funding from CL-Davis Foundation, attended the Veterinary Pathology Congress-2013 held in India. The Congress included the 30th Annual Conference of Indian Association of Veterinary Pathologists (IAVP), the 4th Annual Meeting of Indian College of Veterinary Pathologists (ICVP), and the 8th C.L. Davis Satellite Seminar presented in India. Dr. Bell was invited to present the C.L. Davis Seminar. The seminar focused on avian pathology, including avian diseases, avian wildlife, and pet birds. After the Congress, Dr. Bell toured small poultry operations, where she was invited to perform diagnostic gross examinations. Once home from India, Dr. Bell gave a presentation at WVDL to share the details of her trip.
Low Temperatures and Negative Energy Balance in Calves
– Don Sockett and Melissa Behr, WVDL; Tom Earleywine, Land O’Lakes
The WVDL is seeing an exceptional number of dairy calves (≤ 6 weeks of age) with no white fat in the coronary groove of the heart, mesentery, and perirenal tissues which is consistent with the calves not receiving enough feed. This problem usually begins in January or February, but emaciated calves began showing up at WVDL in late November 2013. Many of these calves had a prior illness such as calf scours. Demand for nutrients increases during illness; in particular the demand increases for protein, energy and fat-soluble vitamins. These nutrients are needed for maintenance, tissue repair, immune function, and to provide body heat. Optimizing nutrition of sick calves can make the difference between a dead and a healthy calf.
When the ambient temperature drops to 15 °F, feeding 3 quarts of milk (12.5% total solids) or its equivalent in milk replacer (MR) twice a day will provide an 88 lb. calf with enough nutrition for 0.5-0.75 lbs/hd/day of growth. However, if the calf is stressed further (draft, wet or dirty hair coat, develops scours, pneumonia etc.) there is insufficient energy and protein in the diet to meet the needs of the calf and it will begin losing weight. Since calves are born with only 3-4% of body weight as fat, they can become emaciated and die if energy balance is negative for > 3-5 days. Since calf scours is a common problem on US dairy operations, winter feeding programs should be formulated to take into account the increased protein and energy demands caused by calf scours. Also, calves should be provided with a jacket and kept in a dry, draft-free environment that is bedded with straw that is deep enough to cover its legs when lying down. Calves should be offered a highly palatable calf starter that is high in protein (18-22%) and energy beginning at 2-3 days of age, and have access to free-choice warm water within 30 minutes of being fed milk or MR.
Winter Feeding Program
Since ruminants do not metabolize fat as efficiently as non-ruminants, just providing more fat in the diet is the least satisfactory way of providing additional nutrition to the calf. The diet must have enough energy and protein so the calf can have efficient, lean growth, adequate immune function, and healing of damaged tissue caused by events like scours or pneumonia.
The dairy producer has 3 options available:
Continue to feed the calves 3 quarts of milk or MR twice a day but increase the total solids content from 12.5 to 15%. To avoid problems, producers need to work closely with their dairy calf nutritionist if they choose this option.
Continue feeding the calves twice a day but increase the volume of milk or MR fed per feeding from 3 to 4 quarts.
Feed the calves 3 quarts of milk or MR three times a day instead of twice a day. There should be at least a 13-14 hour interval between the first and third feeding. This is the best option because calves do better when they are fed three times a day instead of twice a day.
The FDA has recently released an official product safety report on chicken jerky pet treats. Warnings have been issued since 2007 against the use of these products due to their apparent correlation with renal failure, yet as of September 2013 over 3000 complaints have been filed.
During 2007, FDA noted a number of adverse event consumer complaints associated with consumption of jerky pet treats. Product testing did not identify a causative agent, thus FDA issued a cautionary warning regarding chicken jerky products to consumers in 2007 and a Preliminary Animal Health Notification in 2008. There were fewer complaints during 2009 and 2010, but increasing numbers in 2011 generated a third FDA warning in November of the same year. As of September 24, 2013, FDA has received approximately 3000 reports of pet illnesses which may be related to consumption of the jerky treats.
Vet-LIRN became actively involved in pet jerky treats investigation at the end of 2011. We obtain medical histories of pets that have been seen by a veterinarian, and based on the case profile, we plan and organize testing of treats collected from the consumer. Testing is performed by FDA laboratories and other animal health diagnostic laboratories in our network. Vet-LIRN also coordinates collection and testing of diagnostic material and tissues from affected animals. Our cooperation with experts from government and veterinary diagnostic laboratories across the country will provide a high level of professional expertise to provide greater insight into pet jerky treats related illness. The most recent document describing the Investigation Rationale and Results was posted October 22, 2013.
PCR Assays developed at WVDL help identify cause of death of bison
Dr. Scott Jones Diagnostic Pathologist and Supervisor, Barron Lab DVM, Michigan State Univ., 1978
The cause of death of a bison at the Irvine Park Zoo in Chippewa Falls was recently solved by Dr. Jones by using one of the diagnostic PCR assays developed at WVDL. Blood from the bison tested positive for malignant catarrhal fever (MCF) an uncommon but deadly disease in bison. Read more about the incident here:
Epizootic Hemorrhagic Disease (EHD) confirmed in Wisconsin cattle
MADISON –Animal health officials are urging cattle farmers to take preventive measures against Epizootic Hemorrhagic Disease (EHD) in cattle in light of two recent confirmed illnesses. The Wisconsin State Veterinarian encourages the use of insect control to eliminate biting midges and black flies, which are common carriers of the disease that primarily affects deer, but can also infect cattle and other ruminants.
“We already have reports of EHD in Wisconsin cattle, and until we have a hard freeze to kill the midges and flies, the virus will continue to be a threat to our cattle population,” said Dr. Paul McGraw, State Veterinarian.
EHD in cattle is rare, but can happen when environmental conditions support insect growth. Signs include fever, ulcers in the mouth and gums, swollen tongue, excessive salivation, and lameness or stiffness when walking. Death loss is uncommon in cattle. There is no evidence that the EHD virus can infect humans or that it is transmitted between animals.
“The symptoms of EHD are similar to those of Foot and Mouth Disease. So, farmers who notice signs of illness in cattle are encouraged to immediately contact their veterinarian to rule out a possible foreign animal disease,” McGraw said.
On Friday, Sept. 20, Dr. Donald Sockett gave a poster presentation on bovine respiratory disease (BRD) at the American Association of Bovine Practitioners (AABP) Annual Conference in Milwaukee. The most interesting findings of this study follow. The link to view Sockett’s poster is included below.
Dr. Donald Sockett Veterinary Microbiologist DVM, Univ. of Guelph, 1981 PhD, Univ. of Wisconsin, 1991 Diplomate, A.C.V.I.M.
Mycoplasma bovis and bovine respiratory corona virus were found in a high number of calves (≥ 50%) with BRD.
Treated calves with BRD consumed less dry feed (calf starter) and had poorer feed-to-gain ratios than calves that did not have BRD.
There was no difference in milk replacer consumption between calves with BRD (even if treated) and calves that did not have BRD, thus indicating that a reduction in liquid feed ( milk or milk replacer) intake is not a reliable metric to use for early detection of BRD.
Even if treated, calves with BRD weighed less at weaning time than calves that did not have BRD.
Pre-weaned calves that had a bout of BRD severe enough to require treatment with antimicrobial drugs should be fed milk or milk replacer for a longer period of time than calves that have not had BRD. The longer feeding time will give the BRD affected calves the time they need to catch up (growth) with the calves that did not have BRD.