Module 9 2.Patho: Describes the four main classes of infectious microorganism: Fungus

Question 1

What are fungi?

Answer 1

Fungi are relatively large eukaryotic microorganisms with thick walls.

Question 2

What are the two basic structures of fungi?

Answer 2

What are the two basic structures of fungi?

Question 3

What are fungi that can exist in both yeast and mould forms called?

Answer 3

Fungi that can exist in both yeast and mould forms are known as dimorphic fungi.

Question 4

What are fungal cell walls made of, and how do they differ from bacterial cell walls?

Answer 4

Fungal cell walls are made of rigid, multilayered polysaccharides, which are different from bacterial peptidoglycans.

Question 5

How do fungal cell walls’ composition affect their resistance to antibiotics?

Answer 5

The absence of peptidoglycans in fungal cell walls allows them to resist antibiotics like penicillin and cephalosporin.

Question 6

What are the typical oxygen requirements for moulds and yeasts?

Answer 6

Moulds are aerobic, and yeasts are facultative anaerobes, which means they can adapt to anaerobic conditions.

Question 7

How do fungi usually reproduce?

Answer 7

Fungi typically reproduce through simple division or budding.

Question 8

What are mycoses, and what are the three main categories of mycoses?

Answer 8

Mycoses are diseases caused by fungi. They can be categorized as superficial, deep, or opportunistic mycoses.

Question 9

Where do superficial mycoses typically occur, and what is the nature of the diseases they produce?

Answer 9

Superficial mycoses usually occur on or near the skin or mucous membranes and produce mild and superficial diseases.

Question 10

What are dermatophytes, and what diseases do they cause?

Answer 10

Dermatophytes are fungi that invade the skin, hair, or nails. They cause diseases like tineas (ringworm), such as tinea capitis (scalp), tinea pedis (feet), and tinea cruris (groin).

Question 11

How do pathological fungi cause disease?

Answer 11

Pathological fungi cause disease by adapting to the host environment, which may involve digesting host tissues, thriving in diverse temperature ranges, or suppressing host immune defenses.

Question 12

What is the role of phagocytes and T cells in controlling fungal infections?

Answer 12

Phagocytes and T cells play essential roles in controlling fungal infections by eliminating the invading fungi and coordinating immune responses.

Question 13

Why are low white blood cell counts a concern in fungal infections?

Answer 13

Low white blood cell counts can increase susceptibility to fungal infections, especially in immunosuppressed individuals, making infection control crucial.

Question 14

What are some diseases caused by superficial fungi like Malassezia furfur, and what symptoms may they produce?

Answer 14

Superficial fungi can cause tinea versicolor, seborrheic dermatitis, and dandruff. Symptoms may include a red rash on the body.

Question 15

What are the primary diseases associated with cutaneous fungal infections by dermatophytes, and what symptoms can occur?

Answer 15

Dermatophytes cause conditions like athlete’s foot (tinea pedis), jock itch (tinea cruris), and ringworm (tinea corporis). Symptoms include scaling, fissures, pruritus, rashes, and raised borders.

Question 16

Which fungus is responsible for cutaneous candidiasis, and what are some symptoms of this condition?

Answer 16

Cutaneous candidiasis, caused by Candida albicans, leads to lesions on various skin areas, mucous membranes, thrush, and vaginal infections.

Question 17

Which subcutaneous fungus can lead to sporotrichosis, and what are common symptoms associated with this disease?

Answer 17

Sporothrix schenckii causes sporotrichosis, leading to ulcers or abscesses on the skin and other organ systems.

Question 18

Name some systemic fungi that can cause diseases in healthy individuals and describe their respective diseases and symptoms.

Answer 18

Systemic fungi like Stachybotrys chartarum, Coccidioides immitis, Histoplasma capsulatum, and Blastomyces dermatitidis cause diseases with flulike symptoms, lung involvement, chest pains, and dissemination to multiple organs.

Question 19

What are some examples of opportunistic systemic fungi, and what diseases can they cause in individuals?

Answer 19

Opportunistic systemic fungi, including Aspergillus species, Pneumocystis jiroveci, Cryptococcus neoformans, and Candida albicans, may lead to various systemic infections such as pneumonia, pneumonialike illness, skin lesions, sepsis, endocarditis, and meningitis.

Question 20

What is the primary site of infection and disease associated with Malassezia furfur, and what are the symptoms?

Answer 20

Malassezia furfur primarily causes superficial infections, leading to tinea versicolor, seborrheic dermatitis, and dandruff, with symptoms like a red rash on the body.

Question 21

What types of fungal infections are considered cutaneous, and what are some common dermatophytes causing these infections?

Answer 21

Cutaneous infections are characterized by no tissue invasion but an inflammatory response. Dermatophytes, such as Trichophyton mentagrophytes, Trichophyton rubrum, and Microsporum canis, lead to conditions like athlete’s foot, jock itch, and ringworm. Symptoms include scaling, fissures, pruritus, rashes, raised borders, and pruritus.

Question 22

Which fungus causes cutaneous candidiasis, and what symptoms can occur with this infection?

Answer 22

Cutaneous candidiasis is caused by Candida albicans and can lead to lesions in various skin areas, mucous membranes, thrush, and vaginal infections.

Question 23

Name a subcutaneous fungus and the primary disease it causes, along with common symptoms.

Answer 23

Sporothrix schenckii is responsible for sporotrichosis, leading to ulcers or abscesses on the skin and other organ systems.

Question 24

What types of fungal infections are categorized as systemic, and provide examples of dimorphic systemic fungi and their associated symptoms.

Answer 24

Systemic fungal infections can be dimorphic or opportunistic. Dimorphic fungi like Stachybotrys chartarum, Coccidioides immitis, Histoplasma capsulatum, and Blastomyces dermatitidis cause diseases with symptoms like rashes, headaches, nausea, pain, valley fever, flulike symptoms, lung involvement, chest pains, and dissemination to multiple organs.

Question 25

What are some examples of opportunistic systemic fungi, and what diseases can they cause in individuals?

Answer 25

Opportunistic systemic fungi, including Aspergillus species, Pneumocystis jiroveci, Cryptococcus neoformans, and Candida albicans, may lead to various systemic infections such as pneumonia, pneumonialike illness, skin lesions, sepsis, endocarditis, and meningitis.

Question 26

What is the most common cause of fungal infections in humans?

Answer 26

Candida albicans is the most common cause of fungal infections in humans.

Question 27

Is Candida albicans a commensal organism in the human body, and where can it normally be found?

Answer 27

Yes, Candida albicans is a commensal inhabitant in the normal microbiome of many healthy individuals. It can be found in the skin, gastrointestinal tract, mouth (in 30 to 55% of healthy individuals), and vagina (in 20% of healthy women).

Question 28

How is Candida albicans normally controlled in healthy individuals?

Answer 28

Candida albicans is normally under the control of local defense mechanisms, including the bacterial microbiome that produces antifungal agents.

Question 29

What can happen when antibiotic therapy is administered to healthy individuals?

Answer 29

Antibiotic therapy may diminish the microbiome, which can disrupt the balance of microorganisms. This may lead to Candida overgrowth and localized infections, such as vaginitis or oropharyngeal infection (thrush).

Question 30

Who is at risk of disseminated Candida infection?

Answer 30

Immunocompromised individuals, particularly those with diminished neutrophil levels (neutropenia), are at risk of disseminated Candida infection.

Question 31

What is the most common fungal infection in people with conditions like cancer, transplantation, and HIV/AIDS?

Answer 31

Candida is the most common fungal infection in individuals with conditions such as cancer (especially acute leukemia and other hematological cancers), transplantation (bone marrow and solid organ), and HIV/AIDS.

Question 32

What are potential sources of invasive candidiasis?

Answer 32

Invasive candidiasis may be associated with indwelling catheters, intravenous lines, or peritoneal dialysis, which provide direct access to the bloodstream.

Question 33

What are the characteristics and symptoms of disseminated candidiasis?

Answer 33

Disseminated candidiasis involves deep infections in internal organs, with symptoms such as persistent or recurrent fever, Gram-negative shock-like symptoms (hypotension, tachycardia), and disseminated intravascular coagulation (DIC).

Question 34

What are the death rates associated with septic or disseminated candidiasis?

Answer 34

Death rates for septic or disseminated candidiasis typically range from 30 to 40%.