In the Literature

PENGUINS, ANTARCTICA, AND HISTOPLASMA CAPSULATUM

Moreira LM, Meyer W, Chame M, et al. Molecular detection of Histoplasma capsulatum in Antarctica. Emerg Infect Dis 2022; 28:2100–4.

It is often stated that Histoplasma capsulatum has worldwide distribution—and now that it has been identified in Antarctica, this assertion is confirmed.

Moreira and colleagues examined environmental samples collected in the Antarctic Special Protected Area on Antarctica's King George Island for the presence of H capsulatum DNA by polymerase chain reaction (PCR). This site is heavily used by bird species during the summer, serving as a host to bird colonies as well as to many plant species, and is a site for mammal breeding—all making its soil conducive to fungal growth.

The samples included 9 of penguin excreta, 3 of fur seal feces, and 8 of superficial soil. Amplicons were sequenced with identification of H capsulatum in 2 of the 8 soil samples and 3 of 9 samples of penguin excreta. All 5 detected Histoplasma were found to be most closely associated with known South American lineages.

Thus, Histoplasma is truly cosmopolitan. Its detection in Antarctica is not necessarily surprising since the continent has, over the last 2 centuries at least, been subject to innumerable alien invaders of all sorts, including of microorganisms, and its ornithogenic soil provides the conditions for growth of many fungi, including Histoplasma [1, 2]. In fact, de Sousa and colleagues previously recovered 481 fungal isolates, including 368 filamentous fungi and 113 yeasts, from such soils with incubation at 15°C, although only 50 were able to grow at 37°C [2]. Four hundred eighty-one fungal isolates (including 368 filamentous fungi and 113 yeasts) from ornithogenic soils of bird species were obtained after incubation at 15°C in different culture media. Among the organisms isolated were Aspergillus fumigatus, Rhizopus oryzae, Penicillium, Talaromyces, Rhodotorula, and Cryptococcus laurentii.

It is important to recognize that Moreira and colleagues did not attempt to cultivate Histoplasma, so it remains uncertain whether the organisms detected by PCR were viable. At the same time, since warming is occurring at a significantly faster rate in Antarctica than the global average, resulting environmental conditions are likely to make the continent more hospitable to many fungal species.

References

NEUROLEPTOSPIROSIS

Bismaya K, Dev P, Favas TT, Pathak A. Neuro-leptospirosis: experience from a tertiary center of north India [manuscript published online ahead of print 22 September 2022]. Rev Neurol (Paris) 2022. https://doi.org/10.1016/j.neurol.2022.06.009

Leptospirosis has been associated with a broad range of neurological manifestations. While aseptic meningitis is the most common syndrome, other manifestations include encephalitis, myelitis, acute flaccid paralysis, stroke, cranial nerve palsies, mononeuritis, and movement disorders.

Bismaya and colleagues in Varanasi, India, reviewed their institutional experience with 7 patients with neuroleptospirosis. They ranged in age from 14 to 55 years; 4 were male. All had fever and headache and 4 had vomiting. Two patients had seizures and 3 had altered sensorium. One patient, who proved to have a subcortical ischemic stroke, had hemiparesis on presentation. Six had neck stiffness and 2 patients had a cranial nerve palsy. All 7 had a positive polymerase chain reaction result for Leptospira as well as immunoglobulin M antibody to the organism.

Peripheral white blood cell (WBC) count ranged from 9800 to 11 800 cells/mm³. In all patients, serum transaminases were mildly elevated, whereas serum bilirubin and serum creatinine were normal. Cerebrospinal fluid (CSF) opening pressure was normal in all patients, whereas the WBC count was modestly elevated with lymphocytic predominance. Protein was modestly elevated in all but glucose was apparently normal. Brain magnetic resonance imaging was performed in all 7 patients and was abnormal in 2, with a few T2/fluid-attenuated inversion recovery hyperintensities of subcortical white matter in 1 patient; the patient with hemiparesis had an acute infarct in the right corona radiata. All were treated with ceftriaxone for 7 days and doxycycline for 10 days and at the time of discharge, all were improved and 1 patient partially improved.

Nabity and colleagues in Salvador, Bahia, Brazil, previously described leptospirosis as the cause of aseptic meningitis in 5 of 295 (1.7%) patients [1]. However, they only performed diagnostic microagglutination testing on patients with epidemiological risk factors for leptospirosis and, among the 22 tested, 5 (23%) had this infection. CSF findings were similar to those found by Bismaya and colleagues. Alanine aminotransferase was very modestly elevated in 1 of 4, while serum creatinine was elevated (1.8 mg/dL) in 1 of 5. Three of the patients received antibiotic therapy (ceftriaxone in 2 and amoxicillin in 1), but this was not initiated until 4, 8, or 29 days after illness onset. The outcomes were not reported.

Van Samkar and colleagues retrospectively identified 19 patients with leptospirosis who had been admitted to a tertiary care center in the Netherlands, 4 of whom were found to have associated meningitis [2]. They also identified 366 patients with leptospirosis-associated meningitis in the literature and found that the median CSF WBC count was 206 leukocytes/mm³ with lymphocyte predominance. The mortality rate was 3%, and 5% had neurological sequelae.

The diagnosis of leptospirosis in patients with aseptic meningitis in the absence of classical systemic illness, as is the case in many patients, is difficult. Perhaps the best example of this difficulty is the case of a patient with prolonged meningitis that defied diagnosis until the application of next-generation sequencing to the patient's CSF led to the detection of Leptospira santarosai [3].

References

CASE VIGNETTE: PANCOLITIS DUE TO SYPHILIS

Chang H, Tang TY, Kuo CF. Syphilitic pancolitis: a case report with literature review. Int J STD AIDS 2022; 33:618–21.

A 64-year-old bisexual Taiwanese man presented with an 8-kg weight loss over the previous 2 months and, for the last 1 month, watery diarrhea and tenesmus. He reported having had a single episode of receptive anal intercourse 2 months before presentation.

Physical examination was unremarkable and his white blood cell count was normal, whereas his hemoglobin level was 10.2 g/dL, albumin was 2.4 g/dL, potassium was 3.0 mEq/L, and C-reactive protein was 3.1 mg/dL. Occult blood was detected in the patient's stool, but culture for enteric pathogens was negative as was an acid-fast stain, and Amoeba spp were not seen on smear.

Colonoscopy identified diffuse ulcers with mucus coating involving the entire colon, while the terminal ileum was normal appearing. Examination of biopsy specimens from the sigmoid and cecum revealed focal cryptitis and crypt abscess with lymphoplasmacytic infiltrate in the lamina propria. Spiral-shaped organisms were seen with immunohistochemical staining for Treponema pallidum.

His rapid plasma reagin (RPR) was positive at a 1:4 dilution (no confirmatory test is reported) and he was discovered to be human immunodeficiency virus positive with a CD4⁺ T-cell count of 409 cells µL and viral load of 4.53 log copies/mL. He was treated with 3 once weekly intramuscular doses of benzathine penicillin G and initiated on antiretroviral therapy. At 1 month, he was asymptomatic while his RPR remained at 1:4.

In an examination of the literature, Chang and colleagues identified 3 additional cases of syphilitic colitis and, like their case, 2 had no cutaneous manifestations of the infection, although 1 had recent onset of hearing impairment.

Treponema pallidum infection of the gastrointestinal tract has been reported to cause gastritis in addition to colitis and proctitis [1]. In a recent review of lower gastrointestinal syphilis, the most frequent findings among the 52 cases with endoscopy results recorded were anorectal mass in 22 (42%) and anorectal ulcer in 18 (35%) [2]. Endoscopic findings were described, without further description, as proctitis in 4 (8%), sigmoiditis in 1 (2%), and colitis in 3 (6%).

The authors note that the immunohistochemical stain used to detect the organism is not specific to T pallidum since it can cross-react with Brachyspira spp, which are associated with intestinal spirochetosis. Treponema pallidum, however, is unlikely to be visualized with hematoxylin and eosin stain. Brachyspira, in contrast, does take up this stain and also has a characteristic appearance on light microscopy that has been described as a “false brush border.” This is caused by the alignment of the organisms adhering to the surface of the mucosal epithelium without invasion and without a significant inflammatory response.

References