Black Fungus (Mucor or Mucormycosis) Fungal Disease
Mucormycosis is also called black mold, black fungus and mucor longum.
Mucormycosis is a large genus of fungi in the Mucoridae family of the zygomycete class
Mucor. It reproduces with cyst spores and conjugative spores.
Mucormycosis exists in the environment such as soil, manure, grass
and air. It grows well under conditions of high temperature, high humidity and
poor ventilation.
The Asian name is Mucor and the western name is Mucormycosis, also known as black mold and Mucor longum.
The reproduction method uses cyst spores and zygospores to multiply.
The growth environment is high temperature, high
humidity and poor ventilation. It belongs to saprophytic fungi.
Table of Contents
1. Introduction
2. Biological traits
3. Mucor infection
4. appearance characteristics
5. Pathogenicity and immunity
6. Distribution and use
7. Microbiological examination
8. Cause disease
▪ Disease test
▪ Drug contamination
▪ Pulmonary Mucormycosis
9. Principles of Control
Introduction
Mucor and Zygomycota are widely distributed in nature. They
are saprophytic fungi with strong ability to decompose proteins and often cause
food mildew. It is a conditional pathogenic fungus, which causes disease in the
human body only when the body's immunity is low and extremely weak.
Biological Traits of Mucormycosis
Mucor is a multicellular fungus, the hypha is not separated,
the branches are at right angles, sporangia stalks grow on the mycelium, and
spherical sporangia are formed at the top, which contains a large number of
sporangia spores.
On the SDA medium, it grows rapidly at 25°C or 37°C, forming
white filamentous colonies, and the colonies become gray-brown after spore
formation. Mucor has both asexual reproduction and sexual reproduction.
Mucor infectionedit
The drug treatment of mucor infection should be amphotericin
B. If the central nervous system or sinuses are involved, surgical intervention
can be considered to reduce the mortality rate.
What are the Shape features of Mucormycosis?
The hyphae are not septal, multinucleated, branched, and can spread widely inside and outside the substrate, without false roots or creeping hyphae. Does not produce solid colonies.
Single, raceme-shaped or pseudo-axially branched cyst stems are directly produced on the mycelium.
There
is a spherical sporangia at the top of each branch, and there are cysts of
different shapes inside, but no sac holder.
A large number of spherical, oval, thin-walled, smooth cyst spores are produced in the cyst.
After the spores mature, the sporangia burst
and release the spores. Sexual reproduction uses heterogeneous or homologous
coordination to form a conjugative spore. Certain species produce
chlamydospores.
The mucor mycelium is white at the beginning, and then grayish-white to black, which indicates that the sporangia are mature in large numbers.
Mucor mycelium can extend about 3 cm per day, and the production speed
is significantly higher than that of shiitake mushroom mycelium.
Mucormycosis Pathogenicity and immunity
In patients with weakened immunity, mucor infection first occurs in the nose and ears. Mucor enters through the nasal cavity and respiratory tract, and can invade the maxillary sinus and orbit, causing necrotizing inflammation and granuloma.
It can also invade the human brain through the bloodstream. Cause meningitis.
It can also spread to the lungs,
gastrointestinal tract, etc. The disease has a rapid onset, rapid progress,
difficult diagnosis, and high mortality.
Distribution and usage
Mucor has a wide range of uses. It often appears in alcoholic medicine. It can saccharify starch and produce a small amount of ethanol, produce protease, and has the ability to decompose soybean protein. It is mostly used to make fermented bean curd and tempeh in our country.
Many Mucor molds can produce oxalic acid, lactic acid, succinic acid and glycerol, and some Mucor can produce lipase, pectinase, rennet and so on. Commonly used Mucor mainly includes Mucor rouxii and Mucor racemosus. Saprophytic, widely distributed in distiller's yeast, plant residues, decaying organic matter, animal manure and soil.
There are important industrial applications, such as
using its amylase to make koji and wine using its protease to brew fermented
bean curd, tempeh, etc. Representative species such as M. racemosus, M. mucedo,
M. rouxianus, etc.
What is Microbiology inspection for Mucormycosis?
Take pus, sputum, sinus aspirate or autopsy specimens, digest
with 10% KOH, and then microscopically examine. If you see thick hyphae with no
septum, strong refractive index, and sporangia, you can preliminarily identify
them.
What diseases can Mucormycosis cause?
Diseases caused by Mucormycosis. The main strain is M. corymbifer, which can invade blood vessel walls and cause thrombosis and tissue necrosis.
It is usually secondary to diabetes or other chronic wasting diseases, and the disease is acute; severe symptoms can be fatal.
According to clinical
manifestations:
1. Cerebral mucormycosis is caused by mucor from the nasal
cavity and paranasal sinuses to reach the brain along the small blood vessels,
causing thrombosis and necrosis.
2. Pulmonary mucormycosis is mainly manifested as bronchial
pneumonia, but also pulmonary infarction and thrombosis.
3. Mucormycosis of the gastrointestinal tract, which is more
common in the terminal ileum, cecum and colon, esophagus and stomach can also
be involved.
Whats is Mucormycosis Disease Test?
Take the diseased tissue for direct microscopic examination, it can be seen that there is no septal hyphae. Compared with Aspergillus, the hyphae are thicker, have fewer branches, and have not many spores.
The specimens are inoculated on the colonies grown on Sabol's medium, and they start to be white.
Gradient gray-black, mycelium can grow spores, with sporangia spores at the end, and sometimes conjugative spores can be seen occasionally.
Treatment can be amphotericin B, sometimes combined with surgical
resection or drainage.
Drug Contamination
In 2009, a number of blood cancer and lymphoma patients in Hong Kong Queen Mary Hospital died of Mucormycosis infection.
Allopurinol, a drug
produced by Eurochem Pharmaceuticals in Hong Kong to treat gout and excessive
uric acid, is suspected of being contaminated, and the content of Mucor is 100
times higher than the standard.
Pulmonary Mucormycosis
English name: pulmonary mucormycosis alias mucormycosis, mucormycosis, algae disease, zygomycosis,
phycomycosis, zygomycosis, mucormycosis.
Overview: This disease is caused by several possible
pathogens of the Mucoridae family. It often invades the blood vessel wall and
vascular cavity, and causes inflammation and thrombosis. It is often
complicated with diabetes. It is more common in burn patients.
Cause of Mucormycosis
Fungi that can cause pulmonary mucormycosis belong to
the subphylum Zygomycota, Mucor, Mucorales, Mucorales, and occasionally from
other families of Mucorales, such as Mortierellaceae, Cunninghamiaceae, caused
by Kokomyceae, Phalaenopsis, etc. Among them, Rhizopus, Mucor and Absidia are
the three most common types of fungi that cause pulmonary mucor.
Among the three types, Rhizopus is the most common type,
especially Rhizopus and Rhizopus oryzae.
Principles of prevention of Mucormycosis
There are no effective preventive measures and treatment
methods. Antifungal drugs such as amphotericin B can be used in the early
stage, and the lesion can also be surgically removed.
Clinical case: A case of Pulmonary Mucormycosis
X-ray chest radiograph shows that the left lung
field has decreased brightness, uneven density, and the mediastinum and trachea
shifted to the left.
Chest CT showed the disappearance of the left main bronchus opening, the left lung consolidation with atelectasis, the left pleural effusion, and the huge round soft tissue in the left lung.
Fiberoptic bronchoscopy showed that the left main
bronchus was completely blocked by white gelatinous material, and the carina
was white ulcers.
Clinical Information
A 48-year-old female patient with intermittent fever and hemoptysis style=color:blue> hemoptysis for 6 months, exacerbated with suffocation for 7 days.
The patient had a history of type 2 diabetes for 2 years. He developed diabetic ketoacidosis with coma 6 months ago, and developed fever 1 week later. Chest X-ray showed exudative shadow of left upper lung, chest CT showed consolidation of left upper lung with cavity formation.
The patient did
not get better after a variety of broad-spectrum antibiotics, quadruple
anti-tuberculosis and itraconazole antifungal therapy and developed hemoptysis.
Physical examination: left trachea, left lung percussively, and breath sounds disappeared; abdomen was flat and soft, no tenderness, 4 cm below liver ribs; pitting edema of both lower limbs.
Auxiliary inspection:
Peripheral blood leukocytes are 22.7×109/L, neutrophils are
84%, and hemoglobin is 50 g/L.
Multiple sputum smears and cultures were negative, and blood
cultures were negative for bacteria, fungi, and acid-fast bacilli.
The chest radiograph showed a large area of exudate from
the left lung (Figure 1). Chest CT showed consolidation of the left lung with
atelectasis, pleural effusion on the left, and large round soft tissue shadows
in the left lung (Figure 2).
Fiberoptic bronchoscopy showed that the left main bronchus
was completely blocked by a white gel mass (Figure 3). The smear of bronchial
secretions was negative for fungus and culture.
The pathology of the tumor showed a large number of hyphae in
the necrotic tissue, and its morphology suggested that it was a mucor mycelium
(Figure 4).
Diagnosis: pulmonary mucormycosis
Outcome: The patient developed massive hemoptysis (about 3000
ml) on the 7th day of hospitalization, and died after rescue.
Comment
Pulmonary mucormycosis is a severe pulmonary infection caused by some pathogenic fungi in the order Mucorales of the fungal kingdom Zygomycota. It is also called pulmonary zygomycosis (pulmonary zygomycosis).
The body's immunity is reduced (such as diabetic acidosis, hematological
malignancies, and organ transplantation or application of immunosuppressive
agents).
The most common symptoms of this disease are fever and cough. More than half of patients have hemoptysis, chest pain, and dyspnea.
Mucor has
a strong penetrating power and often erodes pulmonary arterioles, causing
pulmonary embolism and pulmonary infarction. If not treated in time, most
patients die of massive hemoptysis.
The most common imaging manifestations of this disease are progressive
and homogeneous consolidation of lung lobes or lung segments. It can also be
manifested as single or multiple pulmonary nodules or masses, more common in
the upper lobe. Holes appear in more than 40% of cases. Air half-moon sign is
less common than pulmonary aspergillosis. Its appearance suggests a tendency to
massive hemoptysis, but the prognosis of the patient is relatively good.
It should be noted that the positive rate of culture of sputum, needle aspiration and bronchoalveolar lavage fluid for pulmonary mucormycosis is <5%, and the diagnosis often depends on histopathology.
The
characteristics of the mucor hyphae are: 7-25 μm in diameter, uneven thickness,
branching at right angles, wide without separation or few separation, and thin
wall.
Once the diagnosis is confirmed, intravenous amphotericin B
should be administered immediately, and surgical resection of the lesion should
be considered for those who have not improved after 2 weeks of treatment. Other
commonly used antifungal drugs are ineffective.
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