adv micro exam 2

Get a hint

hint

The best way to isolate Listeria from a mixed culture is to use:

The best way to isolate Listeria from a mixed culture is to use:

Cold enrichment at 4 C followed by subculture

Upon examination, a 7-day-old infant is found to have mucopurulent discharge from his eye. A Giemsa stained smear of his eye scraping shows intracellular inclusions in epithelial cells. The MOST probable organism is which of the following?

Chlamydia trachomatis

An infant was admitted to the hospital with symptoms of meningitis. A lumbar puncture was performed and cultures were ordered. What is the best tube to be sent to Micro for culture and susceptibility testing?

Tube 2 or 3

Clue cells are found on a direct smear of a vaginal specimen. This indicates a possible infection with:

Gardnerella vaginalis

Endemic trachoma and genital infections are caused by:

Chlamydia trachomatis

The most common type of organisms found in the normal intestinal tract is:

Bacteroides and other anaerobic gram negative rods

Which of the following organisms causes hemolytic uremic syndrome in children associated with consumption of under-cooked beef?

E. coli 0157:H7

Hyphae which has become divided into a chain of cells by the formation of transverse walls at regular intervals are described as being:

Septate

Which of the following is a sexual spore?

Ascospore

Listeria may be differentiated from Group B Beta hemolytic Streptococci by the following tests

Gram stain, catalase

A purulent CSF drawn from and 18 year old male reveals the following: WBC: 200/microliter, 98% neutrophils, protein: 80 mg/dl, Glucose: 20 mg/dl. These findings are MOST consistent with

Bacterial meningitis

Non-gonococcal urethritis (NGU) can be caused by certain species of which of the following:

Chlamydia

You have set up biochemical tests on a non-lactose fermenting colony from Hektoen agar on a stool culture. After 4 hours, the urea slant is bright pink. Select the most appropriate action:

Discard the tests, since the NLF is not Shigella or Salmonella

Which genera of the Enterobacteriaceae are known to cause diarrhea and are considered enteric pathogens?

Escherichia, Salmonella, Shigella, and Yersinia

In the study of molds it is often necessary to observe the relationship between the reproductive structures and mycelium. This is best accomplished by:

Slide culture technique

The slide culture technique is useful to:

Demonstrate undisturbed sporulating structures

The best procedure to differentiate Listeria monocytogenes from Corynebacterium species is:

Motility

The following statement BEST describes the results of a CSF from a patient with bacterial meningitis:

Decreased glucose, increased protein, increased WBCs with PMNs predominating

Soft chancre or chanchoid is due to infection with

Hemophilus ducreyi

E. coli 0157:H7:

All of the above (produces cytotoxin similar to Shigella, is acquired by heating poorly cooked beef, produces hemolytic uremic syndrome (HUS) in children, produces bloody diarrhea)

Microscopically, Vibrio appears as a:

Curved gram negative rod

The thick-walled conidia formed from a pre-existing hyphal cell which detaches from the hyphae is a(n):

Arthrospore

Fungus cultures should be incubated at which of the following temperatures for maximum recovery:

30 C

A CSF was received into your microbiology lab. Upon examining the patient information on the request from and comparing it to the information on the specimen itself, a difference in names is noted. The appropriate course of action would be to:

Phone the physician and ask for a confirmation

A colony on blood agar from a vaginal specimen looks like group B Strep. However, the colonies are catalase positive and gram stain reveals a gram positive rod. It has enhanced umbrella motility at room temperature and grows at 4°C. It probably is:

Listeria monocytogenes

"Clue cells" indicating infection with Gardnerella vaginalis may be observed in which of the following?

saline wet preparation or gram stain of vaginal discharge

Normal flora of the female genital tract (of childbearing age) includes heavy amounts of:

Lactobacillus

Which of the following tests best differentiate Shigella species from E. coli?

Lysine, indole, ONPG, and motility

A mass of threadlike filaments, branched or composing a network, which constitute the vegetative structure of a fungus is:

Mycelia

In the study of molds it is often necessary to observe the relationship between the reproductive structures and mycelium. This is best accomplished by:

slide culture technique

A woman who had recently returned from a vacation in Mexico was admitted to the hospital. She was febrile and complained of flu-like symptoms. Her case history revealed that she had eaten cheese that had been made from unpasteurized milk while on vacation. The most likely etiologic agent in this case would be:

Listeria monocytogenes

The MOST common cause of bacterial meningitis in newborns is:

Gp B strep and E. coli

Bacterial pathogens for newborns, which are always looked for on a routine genital culture from the mother, are:

Group B Beta hemolytic Strep, Listeria

When examining stool cultures for Enterohemorrhagic E. coli 0:157 H7, select the media used and colony characteristics of this organism:

MAC Sorbitol: negative– colorless colony

A lactophenol cotton blue tease prep is prepared on a fungal colony. Upon examination no intact sporulating structures can be found. Select the most appropriate technique which will easily show intact sporulating structures.

Modified slide culture

The most appropriate step to visualize intact sporulating structures on a fungus would be:

Prepare a slide culture with PDA

Small, milky white, beta hemolytic colonies that are catalase negative grow from the CSF of a one-week-old baby. Select the most appropriate work-up:

Camp test or hippurate test

Which virus is associated with genital warts and produce lesions of skin and mucous membranes?

Human Papillomavirus

A small, beta-hemolytic, catalase positive colony has been isolated from a vaginal culture. Gram stain shows gram positive rods and umbrella motility in semi-solid agar. This is most descriptive of:

Listeria monocytogenes

Safety practices in Mycology include

using a biological safety hood

The MOST common pathogens causing meningitis in older children and adults are:

Streptococcus pneumoniae and Neisseria meningitidis

Which of the following are characteristics of Listeria monocytogenes:

causes septicemia and meningitis primarily in neonates and the immunocompromised, umbrella motility at 25°C

Corn meal agar is most useful in:

Stimulating sporulation for identification

Select the method used to screen for E. coli 0157:H7 in stool specimens:

MacConkey containing sorbitol

Which of the following is/are characteristic of Chlamydia trachomatis

Produces inclusion bodies in the cytoplasm of infected cells

A fecal specimen is inoculated with Hektoen enteric agar. Blue-green colonies are isolated. Biochemical screening produces the following key characteristics. TSI: K/A no gas Motility: Non motile Lysine Decarboxylase: Negative Urease: Negative The isolate MOST probably belongs to which of the following genera?

Shigella

In working up a stool culture you carefully pick up four different suspicious colony types and inoculate them to TSI, LIA, and urea. The next day the following results are noted. Which should be worked up further as a possible Salmonella or Shigella?

TSI: K/A/H2S LIA: K/ K H2S Urea: =

Treatment of Vibrio cholera is imperative because of:

Rapid and intensive loss of fluids and electrolytes

A stool pathogen, which requires a media with increased salt such as TCBS, is:

Vibrio

Streptococcus agalactiae is most noted as a cause of:

Neonatal disease

A stool specimen was received in the lab and the clinical history of the patient indicated possible infection with Vibrio. Which additional medium should be inoculated

TCBS (thiosulfate citrate bile salts sucrose) agar

A purulent CSF drawn from and 18 year old male reveals the following:WBC:200/μl, 98% neutrophils Protein: 80 mg/dl Glucose:20 mg/dl These findings are MOST consistent with:

Bacterial meningitis

The organism, which may be confused with Corynebacterium species (diphtheroids) on a Gram stain smear, is:

Listeria monocytogenes

An opportunistic yeast, which never forms mycelia or pseudohyphae, does not have a capsule, and assimilates only glucose and trehalose is most likely

Candida glabrata

The specific type of conidium produced by asexually reproducing yeast is the:

Blastospore

Serious infection by yeast may occur in diabetics, young children, or infants and the immunosuppressed host. What is the most probable causative agent?

Candida albicans

A white, powdery mold with brown reverse pigment is isolated on Mycosel agar in 5 days. Microscopic morphology demonstrates septate hyphae, globose microconidia in grape-like clusters and smooth pencil shaped multi celled macroconidia. Select the most appropriate techniques for definitive identification:

Hair penetration testing, urease

The hair penetration test is utilized primarily to differentiate the following organisms:

T. rubrum, T. mentagrophytes

The Dermatophytes infect which of the following:

Hair, skin, nails

Sporothrix schenckii has the following characteristic

Dimorphic

This organism was isolated from an inflammatory lesion of the skin from the scalp of a young male athlete. Pictured below is the organism on sab dex agar and a lactophenol blue mount. Based on these observations, what is the presumptive identification of the fungus?

T. tonsurans

Which of the following causes Chromomycosis:

Cladosporium species

Which of the following morphological features would correspond to Phialophora sp.?

Urn or vase-shaped phialides

Which of the following on direct exam can differentiate Eumycotic mycetoma from actinomycotic mycetoma:

Microscopic width of the hyphae compared to the width of the branching rods

The slide culture technique is useful to:

Demonstrate undisturbed sporulating structures

A definitive method to fully identify a yeast is:

Carbohydrate assimilation

This organism was collected from an immunocompromised patient with prolonged antibiotic use. The images below are from the cornmeal slide culture of this organism. What is the identification of this organism?

Candida tropicalis

Pictured below is an organism isolated from a lesion of the mouth. What is the presumptive identification of this organism?

Geotrichum candidum

The morphologic structures which identify Candida albicans and distinguish it from other Candida species are:

chlamydospores

The species of fungus causing epidemic ringworm infection in children in the US is:

Microsporum audouinii

A fungus presumptively identified as a Trichophyton is inoculated to T agars. T1 and T2 show scant growth. T3 and T4 show good growth. The organism is:

Trichophyton tonsurans

Species of Cladosporium, Phialophora, and Fonsecaea can be differentiated from each other by:

Pattern of conidial formation seen in microscopic exam from culture

Illustrated in this image is the fruiting head of one of the fungal agents of chromomycosis. Which of the following represents the type of sporulation illustrated here?

Cladosporium sporulation

The thick-walled conidia formed from a pre-existing hyphal cell which detaches from the hyphae is a(n):

Arthrospore

The yeast characterized by "giant hyphae" on cornmeal is:

Candida parapsilosis

The genus of Dermatophytes characterized by the thick-walled, echinulate, spindle shaped macroconidia is:

Microsporum

An organism, which usually causes a lymphatic infection after an initial prick with a rose thorn, is which of the following:

Sporothrix schenckii

A carnation grower in Colorado developed an ulcerated lesion on his hand. With time the infection spread up the lymphatics resulting in several lesions along his arm. The fungus most likely to be responsible for this disease is:

Sporothrix schenckii

A mass of threadlike filaments, branched or composing a network, which constitute the vegetative structure of a fungus is:

Mycelia

A yeast, which produces pink to red colonies, is:

Rhodotoruia

A yeast-like organism has been isolated from a blood culture. No mycelium was produced on corn meal agar, inositol was assimilated, and urease was produced at 35°C. This organism is:

Crytococcus neoformans

If a single budding, yeast surrounded by a wide gelatinous capsule is found in an India ink preparation of the spinal fluid, or is + by Cryptococcal Antigen EIA, the organism is most likely:

Crytococcus neoformans

A dermatophyte, which produces smooth, thin-walled macroconidia singly or in clusters and which does not produce microconidia is:

Epidermophyton floccosum

From a skin scraping culture of tinea pedis, a colony with a very white and powdery surface and patchy reddish-brown reverse pigment has grown. Microscopically, numerous microconidia (en grappe) and spiral hyphae are seen. Hair penetration test is positive. The most likely identification is:

Trichophyton mentagrophytes