Pg 25 - Flashcards
(1) Normal flora of the mouth, throat, large intestine, vagina, skin
(2) Causes mild, opportunistic infections in patients with “mild” metabolic or hormonal disorders (e.g. diabetes, pregnancy, prolonged antibiotic treatment, chronic alcoholism) or those with more extreme moist skin conditions
(3) Can produce life-threatening infections in immunocompromised patients by invading deeper tissues
Candida albicans
Etiological agent of various opportunistic infections – Overgrowth due to reduction of normal flora resulting from antibiotics, hormones, or metabolic disorders
Candida albicans
White, patchy lesions in the mouth; most common in infants
(a) Pseudomembrane covers tongue, soft palate, buccal mucosa & other surfaces
(b) Patches of pseudomembrane often crumble & have the appearance of milk curds
Oral thrush - candida albicans
In oral thrush, _____ covers tongue, soft palate, buccal mucosa & other surfaces
Patches of ___ often crumble & have the appearance of milk curds
pseudomembrane (candida albicans)
Especially in diabetics and pregnant women (due to chemical/hormone changes)
May resemble thrush
vaginitis (candida albicans)
Thrush found in axilla, groin, mammary folds, interdigital spaces – may produce inflammation such as diaper rash
cutaneous thrush (candida albicans)
(a) Nails become hardened, thickened, brownish and discolored
(b) Nail plate is striated or grooved
(c) Mimics tinea u nguim or ringworm of the nails caused by dermatophytes
onychomycosis (candida albicans)
If candida albicans goes systemic, what we got?
infrequent (almost all in immunocompromised or severely debilitated)
(a) Bronchial and pulmonary
(b) Septicemia
(c) Meningitis
(d) Endocarditis
a. Emerging serious global health threat (684 cases as of 14 June 2019)
b. Causes severe INVASIVE infections of blood, heart, brain, eyes, bones
candida auris
c. Often multi-drug resistant
d. Difficult to identify with standard laboratory methods, i.e. misidentification leads to inappropriate medication
e. Causes outbreaks in healthcare settings. Need to rapidly and accurately identify
candida auris
Yeast with thick capsule
Cryptococcus neoformans
(1) Infection in human is almost always pulmonary following inhalation of this yeast; usually subclinical and transitory; may arise as a complication of other diseases in debilitated patients and become rapidly systemic or even fulminant
(2) Central nervous system - meningitis – predilection (affinity) for brain and meninges (more common in AIDS patients)
Cryptococcus neoformans
Laboratory diagnosis
(1) India ink preparation of CSF
(2) Immunodiagnostic test
Cryptococcus neoformans
a. Dermatophytic molds
b. Cause tinea capitis (“ringworm” of scalp), tinea pedis (athlete’s foot), tinea corporis, tinea cruis (jock itch), and toenail fungal infection
c. Diagnosis – KOH wet prep; generally no samples sent to the lab
Microsporum, Trichophyton, and Epidermophyton
tinea capitis (“ringworm” of scalp)
tinea pedis (athlete’s foot)
tinea corporis
tinea cruis (jock itch)
toenail fungal infection
Microsporum, Trichophyton, and Epidermophyton
Fastest fungi growth timelines?
And more importantly, what is the takeaway with fungi growth timelines?
~1 week (many take longer)
Fungus takes much longer to grow/incubate than viruses & bacteria.
So?
Lab growth (and subsequent diagnosis might take time).
Furthermore, antimicrobial efforts also take longer (e.g., toenail fungus can takes up to year)
a. Subcutaneous mold: fungal infection involving the skin and subcutaneous tissue, generally without dissemination to the internal organs of the body.
b. Source - soil, wood, or vegetation – Usually enters through trauma e.g. rose thorns, wood splinters
Sporothrix schenckii
1) Primary lesion - about three weeks after injury
(a) Begins as a small, non-tender, subcutaneous nodule
(b) Nodule ulcerates causing tissue necrosis and infection of nearby lymph channels
(2) Secondary lesions
(a) Develops multiple subcutaneous nodules along lymph channels; may ulcerate
(b) May spontaneously heal but often become chronic, especially if untreated
Clinical presentation of sporothrichosis (Sporothrix schenckii)
Sporothrichosis is commonly called ____ This disease process is an occupational hazard to farmers, nursery workers, florists, forest rangers, and mine workers.
“rose gardener’s disease”
a. Systemic mold pathogen
b. Transmitted via inhalation of spores –often from bird droppings in warm, moist soil
Histoplasma capsulatum
c. Endemic to Ohio River and Mississippi River valleys; also occurs in Africa & Asia
Histoplasma capsulatum
Inhaled as a spore?
Histoplasma capsulatum
coccidioides immitis
Aspergillus fumigatus
Common around Ohio and Mississippi Rivers?
Histoplasma capsulatum
(1) Localized lesions in the lungs – flu-like symptoms (cough, fever) – ~99% of cases
(2) Organism disseminates throughout the body while inside macrophages (inadequate immune response) – < 1% of cases
Histoplasma capsulatum
(a) Cell Mediated Immune response is too weak and lesions develop in major organs.
(b) Acute or chronic infection may develop (pneumonia, hepatitis, meningitis) – usually fatal without treatment
systemic infection from histoplasma capsulatum
a. Systemic mold pathogen
b. Transmitted via inhalation of spores; especially after dust producing event
c. Endemic to semi-arid climate areas of southwestern USA, northern Mexico, and South America – hot, dry, alkaline soil
Coccidioides immitis
Inhaled spores in southwestern USA? Especially after a dust-producing event
Coccidioides immitis
Clinical presentation:
(1) Causes pulmonary lesions and flu-like symptoms – 99% of cases
(2) Disseminates to other organs (central nervous system, bone, cutaneous) when CMI is weak – < 1% of cases. High mortality rate.
Coccidioides immitis
Yes, the same as histoplama capsulatum
But different organisms (i.e., look differently under the ‘scope) and different geography
San Joaquin Valley Fever, Valley Fever, Desert Fever
Coccidioides immitis
A. fumigatus (and other species)
A. flavus
Aspergillus
non-pathogens except in immunocompromised persons, and are found worldwide
A. fumigatus
(1) Transmission – inhalation of airborne spores
(2) Clinical presentation - Usually sinus infection, pulmonary/bronchial mass; sometimes invasive causing multi-organ disease
A. fumigatus
non-pathogens except in immunocompromised persons, and are found worldwide
Aflatoxin when growing in improperly stored (damp) nuts, grains, seeds, and other foods
A. flavus
(1) Transmitted by ingestion of toxin
(2) Clinical presentation – liver damage, often severe
A. flavus (from the aflatoxin)
(1) Attacks interstitial, fibrous tissue of the lungs leading to significant hypoxia
(2) Non-productive cough, shortness of breath, night sweats, fever
(3) Risk increases when CD4 cells are less than 200 cells/uL (immunocompromised)
Pneumocystis jirovecii pneumonia (PCP)
Causes pneumonia in immunocompromised persons, e.g. cancer, chemotherapy, HIV/AIDS – low frequency
Pneumocystis jirovecii pneumonia (PCP)
One of the less common molds that may grow inside buildings where moisture is present; and may produce mycotoxins and pose increased risk of allergy and asthma.
Stachybotrys chartarum
“black mold”
Stachybotrys chartarum
CDC recommends a common-sense approach to prevent and remove mold growth in the home
There is no test that proves an association between Stachybotrys chartarum (Stachybotrys atra) and particular health symptoms
Stachybotrys chartarum
