Mycology

Question 1

Opportunistic mycoses includ ?

Answer 1

Candida
Cryptococcus
Aspergillus 
Mucor , rhizopus 
Pneumocystis

Question 2

Pneumocystis jiroveci classified as ?

Answer 2

Classified as yeast on the basis of molecular analysis , but it has many characteristics of a protozoan

Question 3

Taxonomists renamed the human species of pneumocystis as ?

Answer 3

Pneumocystis jiroveci

Question 4

Taxonomists recommended that P.carnii be used only to describe

Answer 4

The rat species of pneumocystis

Question 5

Pneumocystis is acquired by ?

Answer 5

inhalation of airborne organisms into the lung

Question 6

When inhalat pneumocystis what happan ?

Answer 6

1- Inflammatory exudate composed primarly of plasma cells
2- oxygen exchange is reduced
3- dyspnea occurs

Question 7

Who predispose to pneumonia ?

Answer 7

Areduced number of CD4- postive T lymphocytes ,such as occurs in AIDS

Question 8

Most immunocompetent people

Answer 8

Have asymptomatic pneumocystis infections

Question 9

What is clinical findings of pneumocystis pneumonia ?

Answer 9

Fever 
Nonproductive cough 
dyspnea 
Rales (حشرجه )are heard bilaterally 
Chest X-ray shows a " ground- glass " pattern

Question 10

Mortality rate of untreated pneumocystis pneumonia?

Answer 10

Approximately 100%

Question 11

The dignosis is typically made by ?

Answer 11

Finding the cysts of pneumocystis in bronchial lavage (غسيل )specimens . fluorescent antibody stains or tissue stains , such as methenamine silver or Giemsa , are used to identify the organism . PCR - based tests are also used.

Question 12

Serologic test are useful in pneumocystis ?

Answer 12

No

Question 13

Drag of pneumocystis?

Answer 13

Choice
1- trimethoprim - sulfamethoxazole
2- aerosolized pentamidine :- can be used for prophylaxis in patients with CD4 count below 200

Question 14

Opportunistic fungi

Answer 14

fail to induce disease in most immunocompetent persons but can do so in those with impaired host defenses

Question 15

Candida albicans causes ?

Answer 15

thrush 
vaginitis 
esohagitis 
diaper rash 
chronic mucocutaneous candidiasis

Question 16

Disseminated candida infections causes ?

Answer 16

1- Right - sided endocarditis (especially in intravenous drug users )
2- bloodstream infections (candidemia )
3- endophthalmitis
4- infections related to indwelling intravenous and urinary catheters are also important

Question 17

What is second most common candida ?

Answer 17

Candida glabrata cause of disseminated candidal infections and is more drug resistant than C.albicans

Question 18

Whanlt is candida causes serious bloodstream infections and is highly antibiotic resistant ?

Answer 18

Candida auris

Question 19

How can differentiate cadida albicans from othee species ( C.tropicalis , C.parapsilosis ,C.krusei and C.glabrata) ?

Answer 19

Carbohydrate fermentation reactions

Question 20

Candidia dubliniensis is closely related to C.albicans .it also causes opportunistic infections in immunocompromised patients especially AIDS ,how we differentiate it ?

Answer 20

Both species form chlamydospores , but C.albicans grows at 42C , whereas C.dubliniensis does not

Question 21

Transmission of C.albicans?

Answer 21

As a member of the normal flora is already present on skin , mucous membranes , found throughout GIT (especially the mouth and esophagus ) and vagina . Thrush in newborn is result of passage through abirth canal heavily colonized by the organism ,The presence of albicans on the skin predisposes to infections involving instruments that penetrate the skin , such as needles ( intravenous drug use ) and indwelling catheters . it is often found in the urine of patients with indwelling urinary ( foley ) catheters

Question 22

Immunity against albicans?

Answer 22

The first line of Defense is intact skin and mucous membranes . the second line is cell-mediated immunity, especially Th-1 cells producing gamma - interferon that activates efficient killing by macrophages .Neutrophils are also important as evidenced by the finding that neutropenia predisposes to disseminated Candida infections

Question 23

Candida albicans?

Answer 23

Oval yeast with a sigle bud , it is part of normal flora of skin ,mucous membranes of upper respiratory ,GIT , female genital .
In tissues ,it appears most often as yeasts or as pseudohyphae ( are elongated yeasts that visually resemble hyphae but are not true hyphae .true hyphae are also formed when C.albicans invades tissues

Question 24

Candida ?

Answer 24

Is genes of yeasts and is the most common cause of fungal infection wide ( yeast like funga )
150 plus species , six are frequently associated with human infections
Candida albicans:- is most common species to cause yeast infection . responsible for about 50% of all candida infection
Candida glabrata :- cause infection in ICU pt associate with low survival rate
Candida tropicalis - candida parapsilosis - candida krusei - candida lusitaniae

Question 25

Morphology of candida?

Answer 25

Yeast like - round , oval or elongated , Aerobic and facultative anaerobes

Question 26

Reproduce of candida?

Answer 26

By budding ( blastospores or buds  ) sometimes form pseudomycelia or true mycelia 
Its part of Normal flora , may be found in soil, food and hospital enviroment

Question 27

Source of infection of candida ?

Answer 27

Endogenous
Exogenous
Transmitted sexually from infected female to her partner

Question 28

Predisposes factor of candida albicans?

Answer 28

1- physiological : pregnancy , very young, ( prematuer baby 37 week ,old age
2- immunosupressed pt
3- trauma ( burns ) { Normal flora of skin}
4 - haematological : leukaemia , lymphoma
5- endocrinological : DM , addison , hypoparathyrodism
6- prolonged antibiotic : chronic dirra or steroid therapy contracepptive
7- others : malnutration decreased cellular immunity have decreased resistance to fungal infections
8- invasive procedures : cardiac surgery and indwelling catheters, produce alterations in host physiology

Question 29

Clinical feature of candida albicans?

Answer 29

Superficial infection - Deep infection
1- Oral thrush : painfull small creamy ulcer covered by white pseudomembrane common in neonates , debletating children and adult - extantion to esophagas - fibrosis
2- candida vaginitis : itching ,vaginal discharge common in on pregnant , diaberic , those on contraceptive pills , use of antibiotic suppess the normal flora lactobacillus
3-candida vulvovaginitis : lower abdominal pain,yellowish- white thich oderless vaginal discharge , red and edematous labia minora / in male : candida palanitis : small papules and macules over penis ,become vasicular ,rupture and heal spontaneusly in healthy male
4- intertrigenous candidosis : moist skin ( axillae ,umbilicus area ,intergluteal region ,creases of abdomin and neck in obese people , lesions are red ,irregular margin covered by macerated skin, highly pruritic
5- nail infection: candida paronychia : soft tissue around the nails are affected
6- candida onychia : only nails are affected ; lusterless with discoloration of nail to greenish or brown.
Nail separate from the nail bed, remains hanging ,no accumelation of deberis
6- Esophagitis : retrosternal pain, difficulty inswallowing (AIDS pt and children with chronic mucocutaneous candidosis) ,accompanied by involvement of stomach and small intestine ( pt with leukemia lymphoma)
8- candida enteritis :water diarrheoa
9- UTI
10- meningitis
11- endocarditis
12- endopthalmitis
13- subcutaneaus nodules ( neutropenic pt )

Question 30

Laboratory diagnosis ?

Answer 30

1- specimens : oral& vaginal swabs , sputum,urine , stool ,csf ,skin scarping , nail clipping ..etc
2- Direct microscopy : wet preparation with 10% KOH
3- yeast cells + pseudomycelia = pathognomic
4- stain with gram & methylene blue
5- culture : one blood ager & sabouraud’s with chloramphenicol
6- fungal antigen detection : 1-2 beta d glucan candia mannan assay
7- sensitivity test : ١- germ tube test GTT subculture aerobically in human or horse serum at 37c for 2 hrs microse . germ tube + ve ( candida albicans) ٢- chlamidospore formation : in corn meal agar + tween 80 at 37c for48 - 96 h
٣ - sugar feementation test : zymogram ٤- auxanogram ٥- animal pathogenicity test
8- polymerase chain reaction (PCR ) : detect DNA
9-matrix- assisted laser desorption infection zatiob - time of flight [ MALDI- TOFI] : detect protein

Question 31

Treatment of candida?

Answer 31

1- skin infection and oral thrush consists of tropical antifungl drugs ( clotrimzole or nystatin)
2- vaginal candidosis: tropical ( nystatin or clotrimazole ) or short course of oral fluconazole .
3- nail infection: oral antifungl: itraconazol or ketoconazole tropical antifungl clotrimazole continue for 6-12 months
4- for systemic deep infections: Amphotericin B ,fluconazole, itraconazole