Fungi and Urine

What are the main categories of fungi?

"Yeast, yeast-like fungi, and moulds."

What is a fungus?

"A non-motile eukaryotic organism with definite cell walls, lacking chlorophyll, reproducing sexually and/or asexually."

What is the most frequently isolated fungus in clinical microbiology?

Yeasts.

What is the difference between yeast and yeast-like fungi?

Yeasts reproduce sexually and asexually; yeast-like fungi reproduce asexually (blastoconidia only).

What is the asexual reproductive structure produced by budding yeasts?

Blastoconidia.

What are pseudohyphae?

Elongated budding yeast cells that remain attached after incomplete separation.

Which dimorphic fungi have a yeast phase in vivo?

Blastomyces dermatitidis and Histoplasma capsulatum.

What specimens commonly yield yeasts?

"Respiratory, tissue, vaginal, urine, blood, CSF, skin/nails, bone, and corneal specimens."

Why should direct fungal examination be performed?

To support diagnosis and provide early clues to fungal identity.

Do most yeast cultures require special handling precautions?

"No, except respiratory specimens should be handled carefully due to possible dimorphic pathogens."

Typical appearance of yeast colonies?

"White/cream, pasty, dry, bacteria-like colonies."

What test rapidly identifies Candida albicans and Candida dubliniensis?

Germ tube test.

How long should the germ tube test be incubated?

2-3 hours at 37C (maximum 3 hours).

What media are commonly used for yeast workup?

"Colorex Candida Plus, Mycobiotic agar, and Inhibitory Mold Agar (IMA)."

What technology is now commonly used for rapid yeast identification?

MALDI-TOF mass spectrometry.

What score is generally acceptable for MALDI-TOF yeast identification?

‚>2.00.

What molecular methods can identify clinically significant yeasts?

PCR amplification and sequencing of 26S rRNA and ITS regions.

What are the key features of Candida albicans?

"Germ tube positive, green-blue Chromagar colonies, chlamydospores, cycloheximide resistant."

What differentiates Candida dubliniensis from C. albicans?

Clustered chlamydospores and dark green Chromagar colonies.

What are the key features of Candida glabrata?

"Germ tube negative, mauve colonies, no pseudohyphae or chlamydospores."

What are the key features of Candida tropicalis?

Metallic blue colonies and vigorous pseudohyphal growth.

Which Cryptococcus species commonly infects healthy individuals?

Cryptococcus gattii.

What confirmatory tests are positive for Cryptococcus?

Urease positive and caffeic acid positive.

How are Cryptococcus neoformans and C. gattii differentiated?

"CGB agar: C. gattii positive, C. neoformans negative."

Why is Candida auris clinically important?

"Multidrug-resistant, healthcare-associated spread, high mortality, and reportable."

What antifungal susceptibility test is commonly used for yeasts?

Sensititre YeastOne.

What percentage of hospital-acquired infections are UTIs?

Approximately 30-40%.

What is the most common route of UTI infection?

Ascending infection.

Why are UTIs more common in women?

Shorter urethra and proximity to the anus.

What are symptoms of pyelonephritis?

"Dysuria, flank pain, CVA tenderness, fever, chills, malaise."

What are symptoms of cystitis?

"Dysuria, frequency, urgency, suprapubic pain."

What are examples of complicated UTI risk factors?

"Pregnancy, catheters, diabetes, urologic abnormalities, immunosuppression."

Name major host defenses against UTIs.

"Urine flow, low pH, urea, epithelial shedding, immunity."

What virulence factor helps bacteria adhere in the urinary tract?

Fimbriae.

Which organism is the most common cause of UTI?

Escherichia coli.

Which organism commonly causes UTIs in young women and is nitrite negative?

Staphylococcus saprophyticus.

How should a clean-catch urine specimen be collected?

"Clean genital area, discard initial stream, collect midstream urine."

How quickly should urine be processed?

Within 2 hours or refrigerated at 4C.

What preservative may be used for urine transport?

Boric acid/sodium borate-formate.

Name two unacceptable urine culture specimens.

Urine collection bag specimens and Foley catheter tips.

What urinalysis marker indicates pyuria?

Leukocyte esterase.

Which urine test detects nitrate-reducing gram-negative bacteria?

Nitrite test.

What media are routinely used for urine cultures?

"Blood agar, MacConkey agar, and Orientation agar."

"Using a 0.001 mL loop

one colony represents how many CFU/mL?","1,000 CFU/mL."

What colony count traditionally indicates significant bacteriuria?

"‚100,000 CFU/mL (10^5 CFU/mL)."

How are cultures with ‚â•3 potential uropathogens usually reported?

Mixed flora.

Name common normal urogenital flora.

"Lactobacillus, viridans streptococci, Corynebacterium, Micrococcus, Gardnerella."

Which uncommon gram-positive UTI pathogen resembles viridans streptococci?

Aerococcus urinae.

Which urease-positive diphtheroid can cause UTIs?

Corynebacterium urealyticum.

Which antibiotics are considered urine-specific agents?

Nitrofurantoin and fosfomycin.

What resistant Enterobacterales mechanism commonly affects cephalosporin therapy?

ESBL production.

What does VRE stand for?

Vancomycin-resistant Enterococcus.