Agents of Yeast Infections Flashcards
These are the three major of agents:
Candida
Cryptococcus
Pneumocystis
It is considered as the fourth most common cause of blood borne infection in United States and accounting 10% - 15% of hospital-acquired septicemia cases.
Candida albicans
Yeast fungi can be classified into two groups:
Yeast
Yeastlike
Isolates that reproduce sexually, by forming either ascospores or basidiospores, are truly ___
yeasts
isolates that are not capable of sexual reproduction or whose sexual state has not yet been discovered
yeastlike fungi
Macroscopic characteristics:.
Color:
Texture:
Color – white to cream or tan, with a few species forming pink- to salmon-colored colonies.
Texture – mucoid (Cryptococcus spp.), butter-like, velvety to wrinkled
Some yeast isolates, referred to as _____ are darkly pigmented because of melanin in their cell walls
phaeoid yeasts,
most notorious agents of yeast infection
Clinical disease ranges from superficial skin infections to disseminated disease
Candida
- the premier cause of yeast infection in the world.
- recovered as normal biota from a variety of sites, including skin, the oral mucosa, the digestive tract, and the vagina.
C. albicans
One of the most widely recognized manifestations of C. albicans infection is _____ (oropharyngeal candidiasis), an infection of the oral mucosa and recognized as an indicator of immunosuppression.
thrush
- common Candida species that causes disease and may account for 21% of all urinary yeast isolates.
- Infections associated with this tend to be aggressive in patients with multiple comorbidities and may be difficult to treat with traditional antifungal therapy.
C. glabrata
- multidrug-resistant yeast linked to high mortality rates associated with hospital-acquired infections worldwide.
- likely transmitted from patient to patient in health care settings and has caused several outbreaks in
numerous countries.
C. auris
Other notable species of Candida include______, _______
C. krusei and C. tropicalis.
It has become a major cause of outbreaks of nosocomial infections. These isolates are identified by the differences in their carbohydrate assimilation patterns and other secondary testing procedures.
C. parapsilosis
important causes of meningitis, pulmonary disease, and septicemia
Cryptococcus
it is the most notable pathogen in this Cryptococcus genus, is a major cause of opportunistic infection in patients with AIDS.
C. neoformans
commonly found in soil contaminated with pigeon droppings and is most likely acquired by inhalation
Cryptococcus
It is an emerging pathogen, particularly in the Pacific Northwest of the United States, similar to those caused by C. neoformans, targeting primarily immunocompromised patients. It an also cause disease in immunocompetent hosts
C. gattii
used primarily to examine cerebrospinal fluid for the presence of the encapsulated yeast Cryptococcus neoformans
India ink or nigrosine
The use of India ink preparation is being replaced by use of _________because of the former’s low sensitivity and an easy-to-use lateral-flow assay, are recommended for routine use in clinical microbiology laboratories.
cryptococcal antigen tests
The cryptococcal antigen assays detect ___ and ____ in CSF and serum
C. neoformans and C. gattii
are noted for producing blastoconidia only, without producing true hyphae or pseudohyphae on cornmeal agar
cryptococcus
All species of the Cryptococcus genus are urease ____, and the nitrate reaction differs
positive
Production of _____ is a feature differentiating C. neoformans from many other Cryptococcus spp.
phenol oxidase
A key laboratory characteristic is that C. gattii uses ___ as a sole carbon and nitrogen source in the presence of canavanine, whereas C. neoformans does not.
glycine
________ is commercially available and can be used to differentiate between C. neoformans and C. gattii.
Canavanine glycine bromothymol blue agar
noted for their bright salmon pink color.
They resemble the cryptococci because they bear a capsule and are urease positive
Rhodotula
They resemble the cryptococci because they bear a capsule and are urease positive. And some species are nitrate positive
Rhodotula
They are not common agents of disease but have been known to cause opportunistic infections.
Rhodotula
inhabit the lungs of many mammals
Pneumocystis
_______was originally classified with the protozoa, but nucleic acid sequencing showed conclusively that the organism is a fungus.
Pneumocystis carinii
_________is the species most commonly found in rats,
P. carinii
is the species most often recovered from humans.
P. jirovecii
acquired early in life; serologic studies have shown that most humans have antibodies or antigens by ____
2 to 4 years of age.
it was initially identified as the causative agent in interstitial plasma cell pneumonia seen in malnourished or premature infants.
pneumocystis
Since the early 1980s, it has remained one of the primary opportunistic infections found in patients with AIDS
pneumocystis
Patients infected with ______ may have nonproductive cough, difficulty breathing, and a low-grade fever
Pneumocystis
nonfilamentous fungus.
pneumocystis
The life cycle (3) three stages:
Trophozoite – 1 to 5 µm in size and is irregularly shaped
Pre-cyst – 5 to 8 µm
Cyst – thick-walled sphere of about 8 µm containing up to eight intracystic bodies.
MOT: respiratory route – cyst (infective stage)
The spores or _____ are released from the cyst in the lung, and these trophic forms multiply asexually by binary fission on the surface of the epithelial cells (pneumocyte) lining the lung.
intracystic bodies
Sexual reproduction by trophozoites also occurs, first producing a precyst and then the cyst containing spores or intracystic bodies.
True
Diagnosis was made by finding the cyst or trophozoite in tissue obtained through open lung biopsy.
Specimens:
o bronchoalveolar lavage (BAL) fluid o transbronchial biopsy o tracheal aspirate o pleural fluid o induced sputum – least productive specimen
Lavage and sputum specimens are often prepared using a _______
cytocentrifuge
Histologic stains, such as ____ and ________
Giemsa and Gomori methenamine silver stains
With the ______, the cyst wall stains black.
methenamine silver stain
often have a punched-out ping-pong ball appearance.
cyst
With the _____, the organism appears round, and the cyst wall is barely visible.
Giemsa stain
_____ can be used to screen specimens for Pneumocystis and other fungi. This stain detects any organism that contains chitin in its cell wall.
Calcofluor white
Fungi, yeasts, and Pneumocystisspp. will fluoresce with a _______color when stained and viewed microscopically with ultraviolet light.
blue-white
