Studied by 1 person
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
Note
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