AHA and mycoplasma haemominutum - chicken or egg?

Re: AHA and mycoplasma haemominutum - chicken or egg?

Martin Atkinson — Fri, 20 Jun 2014 14:29:13 GMT

Update on this case. The cat has recovered well no longer icteric but it remains stubbornly non-regeneratively anaemic with a HCT of 21%. Platelet count remains low at 33x10^10/l but there is evidence of platelet clumping on slide examination. It has been on doxycycline and 10mg preds daily for 2 weeks. Tested for retroviruses negative. Owner is moaning about costs, doesn't to want to start with bone marrow biopsies and probably won't want to try more expensive treatment like cyclosporin or azothyoprin (although last time I looked that is contraindicated in cats) or even supportive therapy with anabolic steroids and EPO.

I think the platelet count is an artifact although why this cat should clump its platelets on repeated sampling is a bit of a mystery. Plan is to slowly reduce the preds and monitor the HCT if it remains stable and wean down to a maintenance dose and accept 20% or so.

Any better ideas in the light of the restrictions put on me as illustrated above?

Re: AHA and mycoplasma haemominutum - chicken or egg?

Andrew Kent — Wed, 11 Jun 2014 13:03:58 GMT

No Problem.

As an aside:

[quote user="Martin Atkinson"]Whichever, even the purveyors of more expensive/sophisticated machines will admit that the QBC Autoread is the only benchtop analyser that gives an accurate platelet count or plateletocrit if you like.[/quote]

These are different things and it is both the benefit and downfall of the QBC. The QBC only measures plateletocrit (a measure of mass of platelets) which it then converts to a platelet count based on a standard platelet size. Therefore if the platelets are abnormal (or regenerative) then the platelet count will be meaningless. Unfortunately most of them are not set up to actually give you the plateletocrit which could be much more useful, especially in animals with abnormal platelets (e.g. CKCS).

So its platelet count is not accurate, especially in this kind of situation where there may well be macro platelets etc.

Andy

Re: AHA and mycoplasma haemominutum - chicken or egg?

Martin Atkinson — Wed, 11 Jun 2014 09:18:21 GMT

Thanks for that Andrew. I could have course dug that out myself but you saved me the trouble. Thanks again.

Re: AHA and mycoplasma haemominutum - chicken or egg?

Andrew Kent — Tue, 10 Jun 2014 21:34:46 GMT

The following abstract from ACVIM 2005 would suggest that M haemominutum can have some pathogenic effects:

Candidatus Mycoplasma haemominutum Infections in Client-Owned Cats

ACVIM 2005

C.A. Reynolds; M.R. Lappin

Colorado State University, Fort Collins, CO

18284230

Mycoplasma haemofelis and Candidatus Mycoplasma haemominutum are parasites of feline erythrocytes. In experimental inoculation studies performed to date, most cats inoculated IV with M. haemofelis isolates developed transient fever and severe hemolytic anemia, whereas cats inoculated IV with Candidatus M. haemominutum isolates remained clinically normal or developed mild anemia. Because only small number of isolates have been studied to date and naturally-infected cats are not likely to be inoculated IV, the pathogenic potential of different Candidatus M. haemominutum isolates is largely unknown. The purpose of this study is to report the clinical findings of a group of cats naturally infected with Candidatus M. haemominutum.

The laboratory records section of the Infectious Diseases Diagnostic Laboratory was searched for all feline cases from which samples had been submitted for Mycoplasma spp. PCR between January 2001 and June 2004. The cats were stratified into the following groups based on the results of a PCR assay capable of amplifying and differentiating DNA of the two Mycoplasma spp.: M. haemofelis alone; Candidatus M. haemominutum alone; both Mycoplasma spp.; and neither Mycoplasma spp.. The referring veterinarian of all cats that were PCR assay positive for DNA of Candidatus M. haemominutum was contacted and the complete medical record requested. The records were reviewed to determine clinical abnormalities, laboratory abnormalities, evidence of concurrent disease, treatment, and response to treatment.

Of 332 cats tested, 42 cats (12.7%) were PCR positive for DNA of Candidatus M. haemominutum alone. Complete medical records were available for 21 of the clinically ill cats. Fever, anorexia, lethargy, weight loss, and anemia were among the most common presenting abnormalities recorded by the referring veterinarians. Housing history was known for 17 cats; 16 were allowed outdoors. Anemia was a laboratory abnormality in 12 cats. Of these cats, six had evidence of other diseases that could have been the primary cause of anemia or could have activated haemoplasmosis. Those diseases included feline leukemia virus (two cats), immune-mediated myeloid and erythroid maturation arrest, lymphosarcoma, erythroid myelosis, and an unknown cause of polyarthritis. For six cats, 'Candidatus M. haemominutum' was the only recognizable cause for the anemia. Of these cats, five were treated with doxycycline or enrofloxacin with or without a glucocorticoid and the anemia and other abnormalities resolved.

The combination of anemia, detection of 'Candidatus Mycoplasma haemominutum' DNA in blood, exclusion of other causes of anemia or immune deficiency, and apparent response to therapeutic protocols that included drugs with known anti-hemoplasma activity suggests that some 'Candidatus M. haemominutum' isolates cause anemia in naturally-infected cats.

Re: AHA and mycoplasma haemominutum - chicken or egg?

Martin Atkinson — Tue, 10 Jun 2014 18:19:47 GMT

[quote user="Andrew Kent"]I thought the QBC only gave an accurate plateletocrit rather than platelet count? In which case I would be confirming manually.

[/quote] It reads it out as nx10^9/L like the WBC count rather than the haematocrit which is given as a %. Whichever, even the purveyors of more expensive/sophisticated machines will admit that the QBC Autoread is the only benchtop analyser that gives an accurate platelet count or plateletocrit if you like. IV vincristine didn't give an immediate increase in apparent platelet count which it would in a dog with autoimmune thrombocytopaenia, so although I took 2 very clean samples maybe the little devils have clumped.

Still that's not the issue really I still wonder about the role of the haemotrophic Micoplasma

Re: AHA and mycoplasma haemominutum - chicken or egg?

Andrew Kent — Tue, 10 Jun 2014 17:33:17 GMT

I thought the QBC only gave an accurate plateletocrit rather than platelet count? In which case I would be confirming manually.