Hello Readers! I'm back after some busy weeks and an overseas holiday, and am pleased to announce that I have a guest author for this and next week's post, Mr. Jacob Rattin. Our case for this week was donated by Dr. Susan Butler-Wu, Dr. Ria Vergara, and Lowel Ordono. They noticed this intriguing findings in a wet preparation of BAL specimen from an immunocompromised patient and worsening respiratory status. The specimen had been stored refrigerate for >24 hours. Identification?
11 comments:
I think it is a ciliated respiratory epithelium cell, but I am not an expert by any means.
Lophomonas blattarum
My guess would be that we aren't seeing a parasite or even an environmental microbe in this specimen, but rather a detached epithelial cell with cilia.
At first thought, it may seem to be a ciliated epithelial cell. However, these cells have a columnar morphology and the cilia are quite short. The object in the picture is rather spherical with definite flagella. Thank you the identification of the crested protozoan found in the gut of roaches. Now we have an EID to learn about.
Florida Fan
So after reading more about Lophomonas blattarum and it's differences to ciliated epithelial cells under light microscopy, I'm inclined to change my answer to Lophomonas blattarum.
Table 1 within the following article describes some helpful key differences:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7365494/#!po=28.8462
Cytociliophthoria, possible morphology effect of viral infection or other inflammatory condition
This is a ciliated respiratory epithelial cell. In reasonably fresh specimens the cilia show this kind of motility. The identifications of "Lophomonas blattarum" (a flagellate protozoan of cockroaches) from human respiratory specimens are spurious. I note that most cases of this "parasite" in the literature are from bronchoalveolar lavage specimens which, by nature, will often contain ciliated respiratory epithelial cells.
One paper (Fakhar, et al. 2021) has described PCR positives for L. blattarum from human respiratory specimens. Some would see this "molecular evidence" as convincing.
I reviewed the PCR primers used in these papers. The forward and reverse PCR primers in a standard “all-sequences on Genbank” BLAST showed the first series of hits to flagellates of various forms (L. blattarum and a lot of different trichomonads), all at 100% identity for both primers. This does raise the possibility that the positives they identified were actually Trichomonas tenax, which is normal oropharyngeal flora, or another unidentified commensal trichomonad of the oral cavity.
I also BLASted four Genbank sequences from two papers describing PCR positives for L. blattarum in human respiratory specimens, these sequences were; MN243135, MN243135, MZ093070, and MN243135. These were all 100% identity to other "human pulmonary L, blattarum" cases identified using the same primers,. All but one from the same group (one was from an unpublished "case" in Thailand using the same PCR primers). This becomes a circular argument, "we have Lophomonas sequences, because when we BLAST our L. blattarum PCR product sequences we have 100% identity to other Lophomonas sequences which we have deposited on GenBank after using our PCR." All of these tested Genbank sequences also had >98% identity with assorted other trichomonad sequences.
I would like to see a confirmed Lophomonas blattarum from a cockroach sequenced and that sequence compared to those "human cases" deposited on GenBank. I owuld also like to see the PCR being used validated against cockroach Lophomonas DNA extracts and human trichomonads.
In summary, I do not believe that Lophomonas blattarum, a parasite of cockroaches, causes human infection in any form. Based on morphology and the available molecular evidence, I do not believe that the various reports appearing in the literature of human pulmonary L. blattarum infection are correct. In my opinion, the current evidence supports these all being morphological misidentifications of ciliated respiratory epithelial cells and PCR cross-priming with commensal trichomonads of the human oral cavity.
Excellent discussion. The patient is immunocompromised, but I would have to have had a Pathologist review because there's reported motility which I would have likely not have even considered anything other than ciliated columnar bronchial cells. I'd agree some direct sequencing would be wise from a cockroach gut with inclusion in Genbank, with a good study published as research. A wrong dx. here could result in inappropriate tx. for the patient. This was a good case study, but I can't really see the motility on the video as resolution and contrast was a little less than what I'm comfortable.
Certainly an opinion divider this week! I'm looking forward to the answer!
Although there are some reports referring that Lophomonas blattarum was identified in BAL specimens, i think that is very unlikely. I agree with detached ciliated epithelial cells.
If it does turn out to be ciliated epithelial cells as many people believe, I am curious what the mechanism or cause is for their detachment? Unless it was a part of the means by which they were acquired, I'm guessing it's related to the patient's respiratory status?
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