Micro Exam 5

holy shit, chap 10-11 & 46-66

Staphylococcus aureus was isolated from a patient's surgical wound. In a disk diffusion assay, the isolate was found to be resistant to cefoxitin (30 µg disk). With which antibiotic should this patient's infection be treated?

Vancomycin

The concentrations in a broth dilution test that separate the categories of susceptible, intermediate, and resistant are called:

breakpoints

Advantages of automated susceptibility tests (e.g., Vitek 2 and Microscan Walkaway) include but are not limited to:

advanced (e.g., expert) software that recognizes and reports resistance patterns

Chromogenic cephalosporins are used to test for:

production of β-lactamase by the infecting organism

A 15-year-old male was diving in a lake when he inhaled some of the stagnate water. Five days later he was admitted to the hospital, comatose, and in critical condition. A cerebrospinal fluid (CSF) specimen was taken, and several motile amoebae were observed. The patient would most likely be diagnosed with which of the following conditions?

Primary amebic meningoencephalitis
Granulomatous amebic encephalitis
Secondary amebic encephalitis
Chronic granulomatous meningitis

Primary amebic meningoencephalitis

The CSF would reveal which of the following results in infections caused by Nagleria fowleri?

Decreased glucose, increased protein, and negative Gram stain
Increased glucose, increased protein, and positive Gram stain
Decreased glucose, decreased protein, and negative Gram stain
Increased glucose, decreased protein, and positive Gram stain

Decreased glucose, increased protein, and negative Gram stain

Tissues suspected of containing Acanthamoeba cysts can be observed using various stains. A cyst that stains black has most likely been stained with the \__________ stain.

methenamine silver
periodic acid-Schiff (PAS)
Giemsa
Wright's

methenamine silver

A 26-year-old woman has an odorous vaginal discharge, lower abdominal pain, and difficulty urinating. Vaginal secretions are collected and sent to the laboratory for examination 3 hours after collection. No motile organisms are observed on the wet preparation; however, T. vaginalis is suspected. Which one of the following statements explains this discrepancy?

The time between collection and the microscopic examination was prolonged, resulting in loss of motility
The infection is most likely bacterial; therefore a Gram stain should have been performed.
The specimen should have been refrigerated before examination; consequently, the organism was compromised.
No discrepancy is present; this organism in nonmotile

The time between collection and the microscopic examination was prolonged, resulting in loss of motility

Laboratory diagnosis of Toxoplasma gondii is confirmed by:

serologic testing
Giemsa stain
tissue culture
Western blot

serologic testing

The most common and largest roundworm encountered is:

Ascaris lumbricoides
Trichuris trichiura
Strongyloides stercoralis.
Necator americanus

Ascaris lumbricoides

A 4-year-old boy attended day care 3 days per week. He was irritable, and his parents noticed that he had persistent perianal itching. A sticky paddle was pressed against the perianal region and sent to the laboratory for testing. The eggs microscopically observed would most likely have which one of the following morphologic features?

Flat-sided, football-shaped
Bipolar plugs
Thin shell with internal granules
Long with a short buccal cavity

Flat-sided, football-shaped

Direct penetration of which of the following worms results in tissue damage at the site of attachment, blood loss, and an acute gastrointestinal phase demonstrated by an increased eosinophilia?

Hookworm
Threadworm
Pinworm
Whipworm

Hookworm

A 36-year-old man entered the emergency department with bleeding and weight loss several weeks after returning from a trip to South America. A stool sample was taken and microscopically examined. Barrel-shaped eggs with bipolar plugs were observed. The organism can be identified as:

Trichuris trichiura
Ancylostoma duodenale.
Necator americanus
Strongyloides stercoralis

Trichuris trichiura

Löffler syndrome is associated with which roundworm infection?

Ascaris lumbricoides
Strongyloides stercoralis
Ancylostoma duodenale
Trichostrongylus spp.

Ascaris lumbricoides

Humans acquire infection with Trichinella tissue nematode by ingesting undercooked meat that contains the infective encysted larvae. In which tissue do these larvae encyst?

Striated muscle
Meninges
Myocardium
Brain

Striated muscle

A definitive diagnosis can be made in a Trichinella infection on the basis of which of the following findings?

Presence of cutaneous larvae migrans in the skin
Identification of unembryonated eggs in the feces
Presence of adult worms in the feces
Identification of encysted larvae through muscle biopsy

Identification of encysted larvae through muscle biopsy

A child is believed to have a Toxocara cati infection in his eye, which he acquired after playing with a stray cat for several weeks. A serum titer was performed, which revealed a titer of 1:8. This laboratory value can be interpreted as:

diagnostic
negative
normal
insignificant

diagnostic

Systemic involvement is rare in infection caused by Ancylostoma braziliense or Ancylostoma caninum; however, pneumonitis may occur. The antihelminthic therapy used to treat this infection is:

albendazole or diethylcarbamazine
metronidazole or thiabendazole
ivermectin or thiabendazole
mebendazole or ivermectin

ivermectin or thiabendazole

The definitive host and reservoir for Wuchereria bancrofti is:

humans
mosquito
microfilaria
tabanid fly

humans

Chyluria is a result of lymphatic rupture and fluid entering the urine. Another lymphatic condition caused by Wuchereria bancrofti is:

elephantiasis
calabar swelling
river blindness
pruritic rash

elephantiasis

A 36-year-old man who has been traveling through the orient is experiencing a tender region in the inguinal region. A blood film is made, and sheathed microfilariae with four to five subterminal nuclei and two terminal nuclei in the tail are identified using Giemsa stain. The organism is most likely:

Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti

Brugia malayi

A skin snip is performed, and microfilariae with tapered tails, no nuclei, and unsheathed are microscopically observed. The recommended therapy for this infection is:

ivermectin
diethylcarbamazine
antihistamines
mebendazole

ivermectin

The Diphyllobothrium latum tapeworm can reach up to 10 meters in length and can have more than 3000 to 4000 proglottids. The definitive host and reservoir host, respectively, are:

humans and fish
fish and copepods
crustaceans and humans
copepods and crustaceans

humans and fish

The Taenia solium organism, which causes cysticercosis and can grow to be 1.5 to 8 meters long, contains 7 to 13 lateral uterine branches along the proglottid. The intermediate host is:

dogs
cattle
cats
pigs

pigs

The Taenia solium organism, which causes cysticercosis and can grow to be 1.5 to 8 meters long, contains 7 to 13 lateral uterine branches along the proglottid. The intermediate host is:

Taenia saginata
Diphyllobothrium latum
Taenia solium
Hymenolepis nana

Hymenolepis nana

A stool specimen is examined, and the following characteristics are observed:15 to 18 lateral branches on each side, Scolex with four suckers, No hooklets, The intermediate hosts of this tapeworm are:

cats
swine
humans
cattle

cattle

The double-pored tapeworm, Diphyllobothrium caninum, consisting of many small proglottids, measures 10 to 70 cm in length as an adult. The scolex contains four suckers and an armed rostellum. The intermediate host in which infective cysticercoids develop is the:

dog
cat
human
flea

flea

Hydatid disease is associated with which tapeworm?

Spirometra mansonoides
Taenia solium
Echinococcus granulosus
Echinococcus multilocularis

Echinococcus granulosus

The Taenia multiceps tapeworm is 5 to 6 cm long and consists of 200 to 250 segments. It has four suckers in its scolex and a proboscis with 22 to 32 hooks arranged in two rows. This organism causes which condition?

Coenurosis
Sparganosis
Hydatid disease
Cysticercosis

Coenurosis

Fur trappers and veterinarians are at an increased risk for this infection by being exposed to infected animals. The intermediate hosts of the organism, Echinococcus multilocularis, are:

rodents
humans
coyotes
foxes

rodents

In Echinococcus granulosus infections, the hydatid cysts usually occur in which organ?

stomach
intestines
brain
liver

liver

Epileptic seizures, headaches, and mental disturbances all result from infection with the Taenia solium organism. The definitive diagnosis is based on:

observance of eggs in the stool
positive direct fluorescent antibody test
positive India ink stain.
identification of cysts in tissue

identification of cysts in tissue

The intermediate host of the Platyhelminthes is freshwater:

fish
cray fish
crabs
snails

snails

The life-cycle stages of the intestinal trematodes after the eggs are shed from the body via feces are best described as:

metacercariae, miracidium larva, cercariae, and redia.
metacercariae, miracidium larva, cercariae, and redia.
redia, metacercariae, cercariae, and miracidium larva.
miracidium larva, redia, cercariae, and metacercariae.

miracidium larva, redia, cercariae, and metacercariae.

The adult form of the fluke, Fasciolopsis buski, is elongated in shape and ranges from 20 to 75 mm long and 8 to 20 mm wide with an oral sucker at the anterior and a ventral sucker approximately midway to the posterior. The reservoir host for the fluke is:

birds
rodents
dogs
fish

dogs

The Heterophyes heterophyes worm, which has a genital sucker that surrounds the genital pore, has a variety of reservoir hosts including dogs, cats, and birds and a second intermediate host of freshwater:

snails
fish
crabs
shrimps

fish

Which second intermediate host ingests the cercariae of Clonorchis and Opisthorchis?

freshwater fish
crustacean
copepod
snail

freshwater fish

Charcot-Leyden crystals are often observed in specimens infected with which one of the following trematodes?

Paragonimus westermani
Opisthorchis viverrini
Fasciola hepatica
Clonorchis (Opisthorchis) sinensis

Paragonimus westermani

The eggs of Paragonimus mexicanus measure approximately 80 µm by 40 µm, are unembryonated and operculated, and have thick shells that are brownish-yellow. An individual with this infection has most likely traveled to which endemic area?

South America
New Guinea
Africa
Japan

South America

Match the following parasites to common names

Lung fluke
Chinese liver fluke
Southeast Asian liver fluke
Sheep liver fluke

Paragonimus westermani
Clonorchis (Opisthorchis) sinensis
O. viverrini
Fasciola hepatica

Lung fluke - Paragonimus westermani
Chinese liver fluke - Clonorchis (Opisthorchis) sinensis
Southeast Asian liver fluke - O. viverrini
Sheep liver fluke - Fasciola hepatica

The eggs of the blood fluke Schistosoma haematobium range from 110 to 170 µm long by 40 to 70 µm wide and have a sharp, pointed terminal spine. In which specimen is this organism most likely found?

urine
bile
sputum
ascites fluid

urine

A large lateral spine is characteristic of which Schistosoma egg?

Schistosoma haematobium
Schistosoma japonicum
Schistosoma mekongi
Schistosoma mansoni

Schistosoma mansoni

An egg of the organism of Schistosoma mansoni is isolated from the feces of an adult man who has been traveling in Africa. An unoperculated egg with a large lateral spine is recovered. The patient is administered the standard dose of praziquantel; however, his infection does not improve. Which one of the following statements explains this discrepancy?

Steroids should have been initially administered.
Bilarcil is the drug of choice for this type of infection.
Metrifonate should have been administered.
A larger dose may be required to be effective against this organism

A larger dose may be required to be effective against this organism

The only intermediate host required in the life cycle of blood flukes is a:

freshwater snail
crustecean
freshwater fish
copepod

freshwater snail

Fungal infections are generally acquired via which route?

nasocomial
vector
inhalation of spores
person to person

inhalation of spores

An example of a dimorphic fungus is

Candida albicans
Aspergillus fumigatus
Cryptococcus neoformans
Coccidioides immitis

Coccidioides immitis

A 16-year-old male teenager is diagnosed with a fungal infection of his foot, which he acquired at the gym. This infection would most likely be classified as a(n) \_______ mycosis.

systemic
opportunistic
subcutaneous
superficial

superficial

A 59-year-old patient with cancer who was receiving high doses of chemotherapy developed a secondary lung infection that was identified as a fungus. The organism disseminated, which ultimately was fatal to the patient. The organism isolated from sputum exhibited septate hyphae that were dichotomous. The organism is most likely which of the following?

Aspergillus
Zygomycetes
Candida
Cryptococcus

Aspergillus

The optimal temperature and length of time to incubate a sample suspected of containing a dermatophyte is \_____°C for \_____ days.

30; 21
30; 72
5; 14
25; 10

30; 21

Which genus is involved in infections of the skin and nails only?

Scopulariopsis
Epidermophyton
Trichophyton
Microsporum

Epidermophyton

The term used to describe ringworm of the nail is:

Tinea capitis
Tinea pedis
Tinea unguium
Tinea cruris

Tinea unguium

The slow-growing organism Trichophyton rubrum produces a flat or heaped-up colony, generally white to reddish with a cottony or velvety surface. The cherry-red color is best observed on the reverse side of the colony. This organism is capable of infecting which of the following?

Hair and skin
Skin, and nails
Hair and nails
Hair, skin, and nails

Hair, skin, and nails

A hair perforation test is performed using Trichophyton mentagrophytes and T. rubrum. The expected results are:

negative for Trichophyton mentagrophytes and positive for Trichophyton rubrum
positive for Trichophyton mentagrophytes and positive for Trichophyton rubrum
negative for Trichophyton mentagrophytes and negative for Trichophyton rubrum
positive for Trichophyton mentagrophytes and negative for Trichophyton rubrum

positive for Trichophyton mentagrophytes and negative for Trichophyton rubrum

Which dermatophyte usually fluoresces yellow-green under a Wood's lamp?

Microsporum audouinii
Trichophyton verrucosum
Microsporum gypseum

Microsporum audouinii

Mycetoma is a subcutaneous infection that involves the lower extremities but may also occur in any part of the body. Swelling, purplish discoloration, and tumorlike deformities of the subcutaneous tissue are all symptoms associated with mycetoma. Which organism can cause this disease?

Pseudallescheria boydii
Bipolaris spp
Exserohilum spp.
Exophiala dermatitidis

Pseudallescheria boydii

An agricultural worker is punctured by a tool used in the field. An infection, characterized by the development of a papule that is similar to a cauliflower appearance, develops. The worker is most likely suffering from which type of infection?

Chromoblastomycosis
Mycetoma
Black piedra
Tinea nigra

Chromoblastomycosis

Which dematiaceous fungus causes a condition known as chromoblastomycosis?

Exophiala jeanselmei
Pseudallescheria boydii
Hortaea werneckii
Phialophora spp.

Phialophora spp.

Macroscopic examination of granules from lesions of mycetoma reveals them to be white to yellow and 0.2 to 2 mm in diameter. Microscopically, the granules consist of loosely arranged, intertwined septate hyaline hyphae cemented together. Which organism can cause a mycetoma infection?

Pseudallescheria boydii
Exophiala dermatitidis
Cladosporium spp.
Fonsecaea spp.

Pseudallescheria boydii

Which form is considered diagnostic in the life cycle of Pneumocystis jirovecii?

cyst
bradyzoite
trophozoite
sporocyte

cyst

Which therapy has decreased the incident of pneumocystis infection in patients with human immunodeficiency virus or acquired immunodeficiency syndrome (HIV/AIDS)?

Aminoglycosides with fluconazole
Metronidazole
Trimethoprim-sulfamethoxazole combination
Highly active antiretroviral therapy (HAART)

Highly active antiretroviral therapy (HAART)

In patients who do not have HIV, which underlying condition is considered a risk factor for acquiring PCP?

Cytomegalovirus
Malaria
Myasthenia gravis
Cystic fibrosis

Cystic fibrosis

Which type of molecular assay has been developed to identify P. jirovecii?

Nucleic acid sequence-based amplification (NASBA)
Strand displacement amplification (SDA)
Transcription-mediated amplification (TMA)
Real-time polymerase chain reaction (PCR)

Real-time polymerase chain reaction (PCR)

The cell membrane of P. jirovecii contains \_______ rather than \_______, which differentiates it from other fungi.

sterols; cholesterol
sitosterol; sterols
ergosterol; sterols
cholesterol; ergosterol

cholesterol; ergosterol

In general, yeast reproduces asexually by the formation of:

blastoconidia
arthroconidia
ascospores
basidiospores

blastoconidia

The most commonly isolated yeast in clinical specimens is:

Candida albicans
Candida tropicalis
Candida dubliniensis
Candida krusei

Candida albicans

Cryptococcus neoformans is widely distributed in nature, and aerosolization is a prerequisite to most infections. This organism is most often associated with exposure to:

pigeon excreta
contaminated soil
contaminated food
rat excreta

pigeon excreta

A patient with diabetes is experiencing creamy patches on his tongue and mucous membranes. Cultures are performed, and yeast is recovered. His diagnosis is most likely:

thrush
candidemia
paronychia
onychomycosis

thrush

A patient with leukemia is diagnosed with a Candida infection after receiving several doses of chemotherapy. The most likely yeast causing the infection is:

Candida tropicalis
Candida parapsilosis
Candida albicans
Candida metapsilosis

Candida tropicalis

Determining urease activity and growth on niger seed agar is helpful in determining which type of yeast?

Cryptococcus neoformans
Candida albicans
Trichosporon
Malassezia furfur

Cryptococcus neoformans

Blood cultures are drawn on a patient suspected of having a fungemia. Positive cultures reveal the presence of chlamydoconidia on cornmeal agar. In addition, the yeast is germ tube positive. The most likely identification of the fungal agent is:

Candida albicans
Candida tropicalis
Candida glabrata
Cryptococcus neoformans

Candida albicans

Which yeast identification system uses chromogenic substrates to assess specific enzyme activity usually detected within 4 hours?

MicroScan
API-20C AUX
Vitek
Uni-Yeast-Tek

MicroScan

Encapsulated yeast is identified in the cerebrospinal fluid (CSF) of a patient with AIDS is mostly likely:

Cryptococcus neoformans
Candida albicans
Candida glabrata
Candida auris

Cryptococcus neoformans

Tinea versicolor is a skin infection characterized by superficial brownish scaly areas most often on the trunk, arms, or shoulders. Which type of replacement therapy places patients at risk for developing this type of skin infection?

Lipid
Hormone
Saccharide
Gene

Lipid

The agency that provides documents and sets standards for antifungal susceptibility testing is the:

Association of Specialized and Cooperative Library Agencies (ASCLS)
Clinical Laboratory Standards Institute (CLSI)
College of American Pathologists (CAP)
National Accrediting Agency for Clinical Library Sciences (NAACLS)

Clinical Laboratory Standards Institute (CLSI)

The Reference Method for Broth Dilution Antifungal Susceptibility Testing of Filamentous Fungi; Approved Standard (M38-A2) describes the guidelines for antifungal susceptibility testing for molds. The suspension must be standardized with a spectrophotometer. Susceptibility testing is determined by which method?

Microdilution
Disk diffusion
Broth dilution
Immunodiffusion

Microdilution

A patient is diagnosed with an invasive Aspergillosis infection. The antifungal therapy that should be administered is:

amphotericin B
griseofulvin
fluconazole
nystatin

amphotericin B

A patient who is positive for the human immunodeficiency virus (HIV) is diagnosed with a Cryptococcus neoformans infection. The attending resident prescribed Griseofulvin; however, the patient's condition did not seem to improve. Which one of the following statements explains this discrepancy?

- The dose should be increased to penetrate the blood-brain barrier.
- Nystatin, which would have been more effective, should have been prescribed.
- Potassium iodide is the therapy of choice, not griseofulvin.
- Griseofulvin is not effective against Cryptococcus neoformans; therefore the therapy should be changed

Griseofulvin is not effective against Cryptococcus neoformans; therefore the therapy should be changed

If Negri bodies are identified in brain tissue through cytologic means, then the virus is identified as a(n):

rabies virus
parvovirus
adenovirus
varicella virus

rabies virus

Amie's, Leibovitz-Emory, and Stuart's are all types of:

transport media
cell lines
cell culture media
automated systems

transport media

The appropriate temperature in which to store specimens for viral isolation is \____°C.

4
25
30
37

4

A 2-year-old girl is suspected of having a rotavirus infection. The specimen of choice to collect to identify the agent is:

stool
blood
urine
throat

stool

The specimen of choice to collect in suspected cases of respiratory syncytial virus (RSV) is:

nasopharyngeal
sputum
throat
buccal mucosa

nasopharyngeal

Which type of swab is not suitable for the collection of a viral specimen as a result of its ability to interfere with certain tests?

Calcium alginate
Dacron
Cotton
Rayon

Calcium alginate

Some viruses have the ability to stimulate uncontrolled growth of the host cells, resulting in cancer. Which virus has oncogenic properties?

Papilloma
Measles
Retroviruses
Influenza

Papilloma

The function of the glycoprotein spike on some viruses is to:

stabilize attachment for the lipid envelope
prevent drying out and the destruction of the virus.
protect the nucleic acid.
allow viral entry into the host cell

stabilize attachment for the lipid envelope

If a virus is referred to as naked, it means it lacks which structure?

Envelope
Capsid
Nucleocapsid
Protein coat

Envelope

The cytomegalovirus (CMV) produces cytopathic effects (CPE) in diploid fibroblast cells in an average of 7 days. The results are available within 16 hours using which type of assay?

Shell vial
Paired sera
Western blot
Conventional cell culture

Shell vial

Adenoviruses are responsible for causing diseases such as keratoconjunctivitis, pneumonia, hemorrhagic cystitis, and gastroenteritis in children. Transmission is usually via:

contact with rodent urine
respiratory secretions
sexual contact
arthropod vector

respiratory secretions

Lymphocytic choriomeningitis (LCM) and Lassa fever are considered which type of virus?

Picornavirus
Arenavirus
Adenovirus
Papillomavirus

Arenavirus

Hantavirus classified in the Bunyaviridae family is transmitted via:

sandfly vector
fecal-oral route
mosquito vector
rodent excreta

rodent excreta

A 45-year-old man living in the western United States begins experiencing headache, fever, and body aches, which he attributes to the flu. His symptoms, however, become worse, and he later develops kidney disease and acute respiratory failure. He is most likely infected with which virus?

Hantavirus
Rabies virus
Adenovirus
Norovirus

Hantavirus

A 36-year-old woman is on a cruise ship and later develops nausea, abdominal pain, vomiting, and diarrhea. She is most likely suffering from which virus?

Hantavirus
Rotavirus
Norovirus
Torovirus

Norovirus

Severe acute respiratory syndrome (SARS) has what characteristic structures when visualized under an electron microscope?

Crownlike surface projections
Glycoprotein spikes
Filamentous structures
Shepherd's hook

Crownlike surface projections

One of the most pathogenic hemorrhagic fever viruses belongs to the \_________ family.

Filoviridae
Picornaviridae
Flaviviridae
Papovaviridae

Filoviridae

This hemorrhagic fever causes disease in humans and nonhuman primates such as chimpanzees, gorillas, and monkeys. It is identified in the laboratory using which type of assay?

Immunodiffusion
Reverse-transcriptase polymerase chain reaction (PCR)
Peptide nucleic acid fluorescence in situ hybridization (PNA-FISH)
Transcription-mediated amplification (TMA)

Reverse-transcriptase polymerase chain reaction (PCR)

A 37-year-old man traveling through South America has a sudden onset of fever, severe headache, and chills. A macropapular rash develops on his trunk, which then spreads to his face and extremities. The vector transmitting this disease is most likely:

mosquitoes
sandflies
ticks
lice

mosquitoes

An 8-month-old female infant is admitted to the emergency department in respiratory distress on Christmas Eve. A nasopharyngeal aspirate is obtained and sent to the laboratory on ice for analysis. The most probable organism that would be isolated is:

coxsackievirus
rotavirus
varicella-zoster virus
respiratory syncytial virus (RSV)

respiratory syncytial virus (RSV)

Mycoplasmas are organisms without cell walls. Which antimicrobial agents would be ineffective in treating infections involving this bacterium?

Penicillin
Tetracycline
Rifampin
Aminoglycosides

Penicillin

Staphylococcus aureus is a gram-positive organism that produces the enzyme β-lactamase, which renders certain types of antibiotics inactive. The mode of action that is prevented in certain antibiotics sensitive to this enzyme is:

deoxyribonucleic acid (DNA) synthesis.
protein synthesis to the 50S ribosomal subunit.
protein synthesis to the 30S ribosomal subunit.
cell wall synthesis.

cell wall synthesis.

Antimicrobial resistance resulting from the normal genetic, structural, or physiologic state of a microorganism is referred to as \________ resistance.

intrinsic
clinical
microorganism-mediated
inherent

intrinsic