Archives
CONTENTS

• The Microbiology of Ears and Other Orifices
• Antibiotics Don’t wear me out
• Christmas and New Year arrangements
• Clin Path Club
• Tail End

Ears

Samples from cases of otitis are regularly submitted to us for microbiology. Ideally swabs should be taken before treatment is tried, but this is often hard to achieve. If a period off treatment can be managed then results will be more rewarding, as antimicrobials can persist in the ear in sufficient quantities to suppress growth of bacteria in vitro, even where they appear to be useless in containing the problem in the ear. If it is necessary to swab soon after treatment, it can be helpful to submit a couple of air dried smears, made by rolling the swab along a clean slide before plunging the swab into transport medium. These slides will be stained with Gram stain and Leishman’s stain to give an indication to the nature of the infection.

Conformational problems, growths in the canal and atopy and allergy, even some behaviour can predispose to otitis. Recurrent infections may result where there is a persistent, possibly asymptomatic otitis media and a ruptured tympanic membrane, in such cases a bulla osteotomy may be required to eliminate the infection and prevent flare-ups.

Organisms which are commonly identified include Staphylococcus intermedius and Malassezia pachydermatis. Malassezia is a yeast which does not grow on routine culture medium but grows well on special media such as Sabouraud agar. It has been interesting to note the number of cases involving heavy growth of Malassezia in the late summer/early autumn period and in some areas this has been relating to flowering heather. It does emphasise the advisability of the specific yeast and fungal culture which is included in the CS+ (Full Culture and Sensitivity) code. 

Other bacteria commonly isolated include E.coli, Proteus mirabilis which can cause significant secondary infection and the dreaded Pseudomonas aeruginosa. 

We rarely see mites in samples from ears. This probably because they escape on route to the lab. Mites are visible to the naked eye of the young and vital, and with the help of a good auroscope or magnifying glass to the rest of us.

Vagina

The canine vagina is another orifice into which bacterial swabs are frequently inserted. A guarded high vaginal swab is required. The use of a suitable speculum or clean auroscope head is essential to eliminate the possibility of perineal contamination.

Swabs should be taken after the start of pro-oestral bleeding. The routine taking of pre-mating swabs is probably not essential but can be useful where there is a history of infertility or previous problems. Breeders are very keen to have the test done but they should be aware that the vagina is never sterile. Some of the organisms isolated can be found in health and disease alike and opinion varies as to whether treatment should administered. More research is needed but as in other areas the over use of antibiotics should be avoided.

Anus

Should you poke a swab into the orifice or should you submit a faeces sample for enteric pathogen investigation? The general answer is a faeces sample. There are a number of reasons why this is the preferred choice. A swab may provide insufficient sample for all the tests that have to be performed for a full microbiological investigation. This can include, routine aerobic culture, anaerobic culture, micro-aerophilic culture and selective enrichment culture for Salmonella. Anaerobes and Campylobacter are more likely to survive transportation in a universal bottle full of faeces than on a swab in transport medium. Due to the intermittent shedding of enteric pathogens 3 faeces samples taken on different days should be submitted.

This is the title of a recent publication by the Department of Health aimed at increasing the awareness of the importance of antibiotics and how bacteria become resistant to them. The publication is aimed at the medical profession and the patient in particular. There are explanations of the nature and cause of common infections and those that antibiotics can and cannot cure. Also an explanation of the difference between virus and bacterial infections and the situations in which antibiotics will not help. But how does the doctor recognise when antibiotics may be beneficial? There is no reference to the role of diagnostic microbiology. This omission has raised fears amongst microbiologists that the role of diagnostic microbiology has not been recognised. The diagnostic microbiology laboratory plays an important part in the fight against anti-microbial resistance. This includes the isolation and identification of infectious organisms and the determination of antibiotic susceptibility. 

The situation is no different in the veterinary profession where there is increasing pressure on the use and choice of antibiotics. How can the microbiologist help? The normal approach to the use of antibiotics is to treat first, and only to consider culturing if things do not go to plan. The decision whether to treat first or culture first is clouded by a number of conflicting pressures.

• The sale of antibiotics creates profit.
• Sending a sample for culture takes time.
• Will the animal deteriorate while the investigation is completed.
• How will the client react to a negative result and the refusal of antibiotic treatment?

Another potential advantage of the culture first, approach, is the antibiotic sensitivity test may reveal that a less expensive, possibly narrower spectrum antibiotic may be used instead of the usual broad spectrum preparation.
Topath Club
Christmas and New Year Holiday Arrangements

As always from the beginning of December the postal service starts to slow down. To reduce the seasonal effect, post early in the day. Use Post Office Special Delivery for time sensitive samples or request a courier collection. Separate serum or plasma where possible and send fresh smears with your haematology samples. Pack samples in accordance with the Post Office regulations.

For further information or assistance please contact Joanne Kenyon - Client Services

Christmas and New Year Holidays

The laboratory will be closed on the following dates and times:-

May we take this opportunity to say thank you for using NWL and may we wish you a very Merry Christmas and a Peaceful and Prosperous New Year

If you have an interesting case you would like to present to the meeting please contact Jane Miller MRCVS on the above number.
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Tail End

Official Opening

A government minister in Turkey was less than delighted when a ram and a calf were sacrificed in his honour during a visit to the city of Izmir.

The minister was there to open a new veterinary hospital on World Animal Day. He was too late to save the calf but he intervened in the proceedings to stop the ram getting its throat cut in the entrance to the new hospital. He observed "On a day like this, especially at the opening of an animal hospital, scenes like this are really not appropriate."

Maybe they were intended to be the first patients.

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