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Fungal Diseases of the Lung (Des Jardins) Cheat Sheet by

Fungal Diseases of the Lung (Des Jardins)

Anatomic Altera­tions of the Lungs

Chronic restri­ctive pulmonary disorder
When fungal spores are inhaled, they may reach the lungs and germinate.
The spores produce a frothy, yeast-like substance that leads to an inflam­matory response.
Polymo­rph­onu­clear leukocytes and macrop­hages move into the infected area and engulf the fungal spores.
The pulmonary capill­aries dilate, the inters­titium fills with fluid, and the alveolar epithelium swells with edema fluid.
Regional lymph node involv­ement commonly occurs during this period.
Because of the inflam­matory reaction, the alveoli in the infected area eventually become consol­idated.
Airway secretions may also develop at this time.
In severe cases, tissue necrosis, granulomas, and cavity formation may be seen.
During the healing process, fibrosis and calcif­ication of the lung parenchyma ultimately replace the granul­omas.
In response to the fibrosis and occasional calcif­ica­tion, the lung tissue retracts and becomes firm.
The apical and posterior segments of the upper lobes are most commonly involved.
Anatomic changes are similar to those seen in TB.
Major pathologic or structural changes
• Alveolar consol­idation
• Alveol­ar-­cap­illary destru­ction
• Caseous tubercles or granulomas
• Cavity formation
• Fibrosis and secondary calcif­ication of the lung parenchyma
• Bronchial secretions

Etiology and Epidem­iology

Fungal spores of various types are widely distri­buted throughout the air, soil, fomites, and animals, and even exist in the normal flora of humans.
300 fungal species may be linked to disease in animals
In plants
fungal disease is the most common cause of death and destru­ction
In humans
most exposures to fungal pathogens do not lead to overt infection because humans have a relatively high resistance to them
Human fungal disease
mycotic disease or mycosis
caused by primary or “true” fungal pathogens that exhibit some degree of virulence or by opport­unistic
or secondary pathogens that take advantage of a weakened immune defense system

Primary Pathogens [Histo­pla­smosis]

Ohio Valley Fever
• most common fungal infection in the United States
• dimorphic fungus Histop­lasma capsulatum
• prevalence of histop­las­mosis is especially high along the major river valleys of the Midwest and South (e.g., in Ohio, Michigan, Illinois, Missis­sippi, Missouri, Kentucky, Tennessee, Georgia, and Arkansas)
• On the basis of skin test surveys it is estimated that 80% to 90% of the population throughout these areas shows signs of previous infection
H. capsulatum
• commonly found in soils enriched with bird excreta, such as the soil near chicken houses, pigeon lofts, barns, and trees where starlings and blackbirds roost
• may be carried by bats
• an individual acquires the infection by inhaling the fungal spores that are released when the soil from an infected area is disturbed
• incubation period for the infection is approx­imately 17 days
When the H. capsulatum organism reaches the alveoli at body temper­ature, it converts from its mycelial form (mold) to a parasitic yeast form.
Only about 40% of those infected demons­trate symptoms, and only about 10% of these patients are ill enough to consult a physician.
Depending on the indivi­dual’s immune system, the disease may take one of the following forms:
asympt­omatic primary histop­las­mosis
acute sympto­matic pulmonary histop­las­mosis
chronic histop­las­mosis
dissem­inated histop­las­mosis
Asympt­omatic histop­las­mosis
• most common form of histop­las­mosis
• Normally it produces no signs or symptoms in otherwise healthy indivi­duals who become infected.
• The only residual sign of infection may be a small, healed lesion of the lung parenchyma or calcified hilar lymph nodes.
• patient will have a positive histop­lasmin skin test result
Acute sympto­matic pulmonary histop­las­mosis
• occur in otherwise healthy indivi­duals who have had an intense exposure to H. capsulatum
• Depending on the number of spores inhaled, the individual signs and symptoms may range from mild to serious illness.
• Mild signs and symptoms include fever, muscle and joint pain, headache, dry hacking cough, chills, chest pain, weight loss, and sweats.
• People who have inhaled a large number of spores may develop a severe acute pulmonary syndrome, a potent­ially life-t­hre­atening condition in which the individual becomes extremely short of breath.
• This is often referred to as spelun­ker’s lung because it frequently develops after excessive exposure to bat excrement stirred up by indivi­duals exploring caves.
• During this phase of the disease, the patient’s chest radiograph generally shows single or multiple infection sites resembling those associated with pneumonia.
Chronic pulmonary histop­las­mosis
• Infilt­ration and cavity formation in the upper lobes of one or both lungs.
• often affects people with an underlying lung disease such as emphysema
• most commonly seen in middle­-aged white men who smoke
Signs and symptoms include fatigue, fever, night sweats, weight loss, productive cough, and hemopt­ysi­s—s­imilar to signs and symptoms of tuberc­ulosis.
• Often the infection is self-l­imi­ting.
• In some patients, however, progre­ssive destru­ction of lung tissue and dissem­ination of the infection may occur.
Dissem­inated histop­las­mosis
• either self-l­imited histop­las­mosis or chronic histop­las­mosis
• most often seen in very young or very old patients with compro­mised immune systems
• Even though the macrop­hages can remove the fungi from the bloods­tream, they are unable to kill the fungal organisms.
• As a result, dissem­inated histop­las­mosis can affect nearly any part of the body, including eyes, liver, bone marrow, skin, adrenal glands, and intestinal tract.
• Depending on which body organs are affected, the patient may develop anemia, pneumonia, perica­rditis, mening­itis, or adrenal insuff­iciency and ulcers of the mouth, tongue, or intestinal tract.
• If untreated, dissem­inated histop­las­mosis is usually fatal.
Screening and Diagnosis
Fungal culture
• gold standard for detecting histop­las­mosis
• A small amount of blood, sputum, or tissue from a lymph node, lung, or bone marrow is cultured.
• The disadv­antage of this test is that it takes time for the fungus to grow—4 weeks or longer.
• not the test of choice in cases of dissem­inated histop­las­mosis
• Treatment delays in patients may prove fatal.
Fungal stain
• a tissue sample, which may be obtained from sputum, bone marrow, lungs, or a skin lesion, is stained with dye and examined under a microscope for H. capsulatum
• A positive test result is 100% accurate.
• e. The disadv­antage of this test is that obtaining a sputum sample can be difficult, and obtaining a sample from other sites requires invasive proced­ures.
• checks blood serum for antigens and antibodies
• When an individual is exposed to histop­las­mosis spores (antig­ens), the body’s immune system produces antibodies (proteins) to react to the histop­las­mosis antigens.
• Tests that check for histop­las­mosis antigen and antibody reactions are relatively fast and fairly accurate.
• False-­neg­ative results, however, may occur in people who have compro­mised immune systems or who are infected with other types of fungi.

Primary Pathogens [Cocci­dio­ido­myc­osis]

• caused by inhalation of the spores of Coccid­ioides immitis, which are spherical fungi carried by wind-borne dust particles
• endemic in hot, dry regions
• .In the United States, coccid­ioi­dom­ycosis is especially prevalent in Califo­rnia, Arizona, Nevada, New Mexico, Texas, and Utah.
• About 80% of the people in the San Joaquin Valley have positive coccid­ioidin skin-test results.
• “California fever,” “Desert rheumatism,” “San Joaquin Valley Disease,” and “Valley Fever.”
• isolated in these regions from soils, plants, and a large number of verteb­rates
• When C. immitis spores are inhaled, they settle in the lungs, begin to germinate, and form round, thin-w­alled cells called spherules.
• The spherules, in turn, contain endospores that make more spherules (the spheru­le-­end­ospore phase).
• The disease usually takes the form of an acute, primary, selfl­imiting pulmonary infection with or without systemic involv­ement.
• Some cases, however, progress to dissem­inated disease.
Clinical manife­sta­tions
• absent in about 60% of the people who have a positive skin-test result
• 40%: cold-like symptoms such as fever, chest pain, cough, headaches, and malaise are often present.
• In uncomp­licated cases, patients generally recover completely and enjoy lifelong immunity.
• In approx­imately 1:200 cases, however, the primary infection does not resolve and progresses with varied clinical manife­sta­tions.
• Chronic progre­ssive pulmonary disease is charac­terized by nodular growths called fungomas and cavity formation in the lungs.
• Dissem­inated coccid­ioi­dom­ycosis occurs in about 1:6000 exposed persons.
• When this condition exists, the lymph nodes, meninges, spleen, liver, kidney, skin, and adrenals may be involved.
• The skin lesions (e.g., bumps on the face and chest) are commonly accomp­anied by arthralgia or arthritis, especially in the ankles and knees. This condition is commonly called “desert bumps,” “desert arthritis,” or “desert rheumatism.”
Screening and Diagnosis
• The diagnosis of coccid­ioi­dom­ycosis can be made by direct visual­ization of distin­ctive spherules in microscopy of the patient’s sputum, tissue exudates, biopsies, or spinal fluid.
• The diagnosis can be further supported by blood tests that detect antibodies to the fungus or from a culture of the organism from infected fluid or tissue.

Primary Pathogens [Blast­omy­cosis]

• “Chicago disease,” Gilchr­ist’s disease, and North American blasto­mycosis
• caused by Blasto­myces dermat­itidis
• occurs in people living in the south-­central and midwestern United States and in Canada
• The infection occurs in 1 to 2 of every 100,000 people in these areas.
• Cases also have been reported in Central America, South America, Africa, and the Middle East.
B. dermat­itidis inhabits areas high in organic matter, such as forest soil, decaying wood, animal manure, and abandoned buildings.
• most common among pregnant women and middle­-aged Africa­n-A­merican men
• The disease also is found in dogs, cats, and horses.
• Primary portal of entry of B. dermat­itidis is the lungs.
• The acute clinical manife­sta­tions resemble those of acute histop­las­mosis, including fever, cough, hoarse­ness, joint and muscle aches, and, in some cases, pleuritic pain.
• Unlike in histop­las­mosis infection, however, the cough is frequently productive, and the sputum is purulent.
• Acute pulmonary infections may be self-l­imiting or progre­ssive.
• When the condition is progre­ssive, nodules and abscesses develop in the lungs.
• Extrap­ulm­onary lesions commonly involve the skin, bones, reprod­uctive tract, spleen, liver, kidney, or prostate gland.
• The skin lesions may, in fact, be the first signs of the disease.
• It often begins on the face, hands, wrists, or legs as subcut­aneous nodules that erode to the skin surface.
Yeast dissem­ination also may cause arthritis and osteom­yel­itis, and involv­ement of the central nervous system causes headache, convul­sions, coma, and mental confusion.
• Standa­rdized serologic testing procedures for blasto­mycosis are not available, and neither is an accurate blasto­mycin skin test.
• The diagnosis of blasto­mycosis can be made from direct visual­ization of the yeast in sputum smears, or the fungus can be cultured.

Opport­unistic Pathogens

Opport­unistic yeast pathogens such as Candida albicans, Crypto­coccus neoformans, and Asperg­illus* also are associated with lung infections in certain patients.
C. albicans
• Occurs as normal flora in the oral cavity, genitalia, and large intestine.
• infection of the mouth, or thrush, is charac­terized by a white, adherent, patchy infection of the mouth, gums, cheeks, and throat.
• In patients with HIV infection, C. albicans often causes infection of the mouth, pharynx, vagina, skin, and lungs
C. neoformans
• Prolif­erates in the high nitrogen content of pigeon droppings and is readily scattered into the air and dust.
• Today, Crypto­coccus is most often seen in patients with HIV infection and persons undergoing steroid therapy
most pervasive of all fungi
• found in soil, vegeta­tion, leaf detritus, food, and compost heaps
• Persons breathing the air of granaries, barns, and silos are at greatest risk.
• usually occurs in the lungs where it may present in the form of allergic bronch­opu­lmonary asperg­illosis, a form of asthma.
• It is almost always an opport­unistic infection and poses a serious threat to patients with HIV infection.


The Physical Examin­ation
Vital Signs
Increased Respir­atory Rate (Tachy­pnea)
• Stimul­ation of peripheral chemor­ece­ptors
• Decreased lung compli­anc­e–i­ncr­eased ventil­atory rate relati­onship
• Pain, anxiety, fever
Increased Heart Rate (Pulse) and Blood Pressure
Chest Pain, Decreased Chest Expansion
Digital Clubbing
Peripheral Edema and Venous Distention
Because polycy­themia and cor pulmonale are associated with severe fungal disease of the lungs, the following may be seen:
• Distended neck veins
• Pitting edema
• Enlarged and tender liver
Cough, Sputum Produc­tion, and Hemoptysis
Chest Assessment Findings
• Increased tactile and vocal fremitus
• Dull percussion note
• Bronchial breath sounds
• Crackles, wheezing
• Pleural friction rub (if process extends to pleural surface)
• Whispered pector­iloquy

General Management of Fungal Disease

Amphot­ericin B
• treatment of choice for most fungal infections
• However, because of the high incidence of nephro­tox­icity associated with amphot­ericin B, the azole antifungal agents now serve as an excellent altern­ative.
Although ketoco­nazole was the first agent in this class, it has largely been replaced with flucon­azole and itraco­nazole.
In addition, a new class of antifu­ngals known as the echino­candins is now available.
Respir­atory Care Treatment Protocols
Oxygen Therapy Protocol
• used to treat hypoxemia, decrease the work of breathing, and decrease myocardial work
• Because of the hypoxemia associated with the fungal pulmonary condition, supple­mental oxygen may be required.
• Because of the alveolar consol­idation produced by a fungal disorder, capillary shunting may be present.
• Hypoxemia caused by capillary shunting is often refractory to oxygen therapy.
Bronch­opu­lmonary Hygiene Therapy Protocol
• Because of the excessive production and accumu­lation of mucus sometimes associated with fungal disease, a number of bronchial hygiene treatment modalities may be used to enhance the mobili­zation of bronchial secret­ions.
Mechanical Ventil­ation Protocol
• may be necessary to provide and support alveolar gas exchange and eventually return the patient to sponta­neous breathing
• Because acute ventil­atory failure is occasi­onally seen in patients with severe fungal disease, continuous mechanical ventil­ation may be required.
• Continuous mechanical ventil­ation is justified when the acute ventil­atory failure is thought to be revers­ible.


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