An analysis of a case study about cyanobacteria and the exposure pathway. The various analyses and methods to diagnose are discussed.
Descriptions about antinuclear antibodies and liver kidney antibody tests, liver histology, perl and rodamine stains were given.
Questions on cyanotoxins (microc...
INTRODUCTION
Cyanobacteria, exposure pathway, and HAB
Cyanobacteria genera, such as Microcystis, Anabaena, Oscillatoria, and Nostoc, among others,
are capable of producing a wide range of toxins, like microcystins, cylindrospermopsins,
nodularin, and anatoxins. The presence of cyanobacteria blooms in water bodies affects water
quality owing to the production of cyanotoxins and odoriferous compounds. In the La Plata basin
one of the most toxic and frequently-present cyanobacteria is Microcystis sp., often producing
microcystin-LR (MC-LR) and [D-Leu]MC-LR. These toxins are considered among the most toxic
hepatotoxins produced by cyanobacteria. Water bodies with them are commonly used for
recreational purposes or as drinking water sources.
Recreational exposure to cyanobacterial blooms mainly involves oral, dermal, and inhalation
pathways, depending on the type of activities undertaken in the water body.
“Harmful algal bloom (HAB), characterized by the exponential growth of several species of
toxin-producing Cyanobacteria, frequently occurs in summer and constitutes a sanitary and
environmental problem all around the world.” DISCUSSION
Signs and Symptoms
Adults had gastrointestinal symptoms (diarrhea) which were rapidly self-limited a few hours after
exposure. The girl continued to present gastrointestinal symptoms, such as diarrhea and
vomiting, developing fatigue and jaundice, and went to the hospital 5 days after exposure.
Lab Tests
Laboratory tests showed increased serum levels of alanine aminotransferase (ALT: 1814
UI·L−1), aspartate aminotransferase (AST: 1946 UI·L−1), total bilirubin (8.15 mg·dL−1), direct
bilirubin (4.8 mg·dL−1), and International Normalized Ratio (INR > 3).
Then girl went to a liver transplant center. From the epidemiological history during a period of
harmful algal bloom (HAB), the final diagnosis was acute liver failure related to cyanobacteria
toxicity.
https://web.brrh.com/msl/GrandRounds/2018/GrandRounds_102318_Abnormal-Liver-Enzymes/
Elevated%20Liver%20Enzymes.pdf
RESULTS
Sampling and values for bloom and foam
The predominant phytoplankton genus on the Uruguayan coast was Microcystis and, in this
season, 57% of the samples studied from Montevideo beaches corresponded to the category
“sampling with cyanobacteria presence but without foam”, surpassing for the first time since
year 2000 the “samples without bloom” (30%). The remaining 13% corresponded to the
category “sampling with cyanobacterial foam”, which were detected during the whole month of
January 2015 in several beaches of Montevideo according to the official reports given weekly by
the Montevideo authorities. On sampling under “sampling with cyanobacteria presence but
without foam” category the mean value was 17 µg·L−1 for chlorophyll-a and 2.9 µg·L−1 for
microcystins, registering maximum values of 276 µg·L−1 and 56 µg·L−1, respectively. In the
, case of those corresponding to the category “sampling with cyanobacterial foam” the mean and
maximum values were 5600 µg·L−1 and 25,700 µg·L−1 for chlorophyll-a; and 2900 µg·L−1 and
8200 µg·L−1 for microcystins.
Patient
The patient had grade II–III encephalopathy and required mechanical ventilator assistance.
Doppler ultrasonography showed hepatomegaly and echogenic images in both lobes. Brain
tomography showed cerebral edema. Laboratory features showed anemia with decreased
levels of hemoglobin (8 g·dL−1) and hematocrit (25.4%). The patient has had a coagulopathy
(INR: 3.5, PT: 26%) derived from the liver failure and serum levels of ALT (1386 IU·L−1), AST
(1268 IU·L−1), total (9.4 mg·dL−1) and direct (4.8 mg·dL−1) bilirubin still increased. Albumin
(2.7 g·dL−1) and ammonium (257 ug·dL−1) serum levels were also altered.
Serological evaluation was positive for antinuclear antibodies (ANAs: 1/320) and liver kidney
microsomal type 1 antibodies (LKM-1: 1/1280), and negative for anti–smooth muscle antibody,
hepatitis A, B, and C viruses, Epstein-Barr virus, and cytomegalovirus.
Antinuclear antibodies (ANAs) and the liver kidney microsomal type 1 antibody (LKM-1 or
CYP2D6 antibody) test is primarily used to help diagnose autoimmune hepatitis. Autoimmune
hepatitis type II was diagnosed on the basis of the positive LKM-1 result. The patient was
treated with three i.v. doses of 20 mg methylprednisolone·kg−1 and 1.5 mg cyclosporine·kg−1.
After a week of treatment, the patient continued with severe coagulopathy and
hyperammonemia, requiring hemodialysis, so they were put on waiting list for liver transplant
and accepted.
Liver Analysis
The liver external macroscopic appearance was irregular and presented cholestasis with a
coarsely nodular surface and some areas with parenchymal extinction. FIGURE 1. Note the
coarsely cholestatic nodular surface and the areas with parenchymal extinction.
H&E. 2A-Areas of hemorrhage around central veins and hepatocyte dropout. Large hepatocytes
were also observed with ballooning and multinucleation, surrounded by a proliferation zone of
small hepatocytes with an increased nucleus/cytoplasm ratio forming pseudo-acini-2B.
However, bile ducts showed conserved features and no portal inflammation was evident.
FIGURE 2.
Reticulin. Reticulin-stained sections (FIGURE 3) showed large areas of weft collapse around the
central veins, hepatocyte dropout, and signs of regeneration with a necrosis pattern consistent
with interstitial hemorrhage and parenchymal extinction. The presence of regeneration process
is evidence as a macronodular nodule with macro trabecular arrangement of two or three
hepatocytes-A. However, centrilobular fibrosis was not observed.
Despite positive LKM-1 results, the liver alterations observed were not characteristic of
autoimmune hepatitis type II.
Microcystins Analysis
Summary: LC/ESI-HRMS (liquid chromatography electrospray ionization high-resolution mass
spectrometry) analysis of MCs in the explanted liver revealed the presence of Microsytin-LR
(MC-LR) (2.4 ng·gr−1 tissue) and [D-Leu1]MC-LR (75.4 ng·gr−1 tissue), which constitute a
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