Micro Exam 2 ASCP Questions

What is successful molecular identification of methicillin-resistant Staphylococcus aureus (MRSA) based upon?

The detection of the S. aureus genes (orfX, nuc, or coa) gene and the mecA gene.

A clean-catch midstream urine specimen from a 30-year-old woman was sent to the microbiology laboratory for culture. The patient had no urinary symptoms, but the urine culture grew out 100,000 cfu/mL of Escherichia coli from two cultures collected 24 hours apart. Which of the following categories would the patient be classified?

Asymptomatic bacteriuria in female patients

Enteroviruses are common etiologic agents of percarditis and myocarditis. To identify a viral infection, viral cultures or immunoassays are typically the tests of choice. However, viral nucleic acid probe testing may be most appropriate in which of the following situations?

If viral culture is too slow to grow or not possible

A tech receives a request for MRSA/MSSA colonization testing on a patient in the hospital. Which of the following is an appropriate area of the body for culture for screening?

Anterior nares

The pathogenicity of Staphylococcus aureus, as well as the frequency with which this organism produces infections, can be attributed to all of the following EXCEPT:

A porous cell wall

All of the following are collected from sterile sites, EXCEPT:

Abscess fluid

A clean-catch midstream urine specimen from a woman was sent to the microbiology laboratory for culture. The patient had a history of dysuria, frequent urination, suprapubic pain, no fever, no flank pain, or any urinary symptoms in the last 4 weeks before her current episode. The urine grew out 1,000 cfu/mL of Escherichia coli. Which of the following categories would the patient be classified?

Acute, uncomplicated UTI in women

A clean-catch midstream urine specimen from a 57-year-old woman was sent to the microbiology laboratory for culture. The patient had a history of fever, chills, and flank pain upon examiation. The urine grew out 10,000 cfu/mL of Escherichia coli. Which of the following categories would the patient be classified?

Acute, uncomplicated pyelonephritis

Which bacterial species is most likely represented by the spreading, gray-white, beta-hemolytic colonies with a "frosted glass" appearance as illustrated in the photograph?

Bacillus cereus

Which of the following is considered a normal skin flora organism?

Bacillus subtilis

A mucoid alpha hemolytic translucent colony suspected of being Streptococcus pneumoniae was isolated from a blood culture. All of the of the following are appropriate tests to make a presumptive or definitive identification of this organism EXCEPT?

Bacitracin susceptibility

All of the following are usually associated with Group A Beta Streptococci, EXCEPT?

Bacteremia

A 3-year old girl was brought to the ER with a temperature of 103ºF, lethargy, and cervical rigidity. Three tubes of cloudy CSF were delivered to the Lab, and preliminary test results showed: WBC: 4,500/µL Differential: 88% neutrophilsGlucose: 15 mg/dL 12% lymphocytesProtein: 140 mg/dLGram stain: No organisms observed From these results, what preliminary diagnosis SHOULD the physician consider?

Bacterial Meningitis

A CSF specimen is received from a patient with suspected meningitis. Positive Gram stain, along with the results shown here suggest what type of condition? Elevated WBC count Neutrophils predominant Marked protein elevation Marked glucose decrease Lactate level = 37 mg/dL

Bacterial meningitis

Streptococcus pneumoniae can BEST be differentiated from the viridans group of streptococci by which characteristic?

Bile solubility

Osteomyelitis can only be diagnosed by collection and subsequent culture of a sample collected from which source?

Bone

A cancer patient was admitted to the hospital with fever, tachycardia, and a drop in blood pressure. Due to the patient being treated for cancer, her chemotherapy had been administrated through an intravenous catheter. To rule out a catheter-related infection, the physician ordered two sets of blood cultures with one set being collected from the catheter site and the second set being collected by venipuncture. After 48 hours, the patient had positive blood cultures that grew Staphylococcus epidermidis. How will the physician know if the Staphylococcus epidermidis present is due to an infected catheter or is a contaminant?

Both blood culture sets (catheter and venipuncture) will be positive

Spinal fluid cultures on a 3-day-old infant revealed beta-hemolytic, gram-positive cocci occurring in pairs and chains. The organism was catalase-negative and bile esculin-negative. Resistance to bacitracin was noted. The other test necessary to identify this organism is a positive test by:

CAMP

The following is the primary virulence factor produced by Streptococcus pneumoniae that prevents phagocytosis:

Capsule

Which of the following test is the most useful in differentiating Listeria monocytogenes from Erysipelothrix rhusiopathiae?

Catalase production

A rapid urine screening test that can be performed to detect the presence of Staphylococcus species is which of the following tests?

Catalase test

Methicillin resistant Staphylococcus aureus (MRSA) is a serious health concern in the hospital environment and also in the community for patients who have had no contact with the healthcare setting. In order to control the spread of MRSA and prevent infection with the organism, it is recommended to screen patients for MRSA prior to being admitted to a healthcare setting. Which of the following antimicrobials is best to use when testing for methicillin resistance?

Cefoxitin

A Gram stain of drainage from an open wound revealed gram-positive bacilli with spores. This description would commonly rule out which one of the following organisms? (Choose the BEST response.)

Clostridium perfringens

The following organism is an anaerobic organism that produces spores and a double-zone of beta-hemolysis.

Clostridium perfringens

Which of the following organisms is most likely to be associated with gas gangrene:

Clostridium perfringens

Which of the following organisms produces a double zone of hemolysis on blood agar?

Clostridium perfringens

A 25-year-old man was experiencing some difficulty in chewing and swallowing food. He had incurred a deep laceration of the lower leg in a lawn mower incident one week before. The wound was healing but signs of infection persisted. The image shows the Gram stain of a spreading, gray colony isolated from an aspirate of the wound, incubated under anaerobic conditions. Three additional bacterial species were recovered on blood agar incubated aerobically. What is the most likely identification of this anaerobic organism?

Clostridium tetani

_______________ is predominantly associated with skin and soft tissue infections (SSTIs), such as abscesses, cellulitis, folliculitis and impetigo.

Community-acquired MRSA

An alpha-hemolytic streptococcus isolated from a urine culture is resistant to optochin and bactracin, grows in 6.5% NaCI broth, and is PYR positive. The organism is MOST likely:

Enterococcus species

Which Enterobacteriaceae is the most common cause of uncomplicated urinary tract infections (UTIs)?

Escherichia coli

When vitreous fluid is collected, it must be transported to the laboratory within 15 minutes and set up immediately for culture. This specimen type must be handled with care as this specimen type is not easy to obtain. What body site is this specimen collected from?

Eye

Each of the following characteristics will differentiate between Listeria monocytogenes and Erysipelothrix rhusiopathiae except:

Fermentation of glucose

Blood specimens are typically sterile; however, if an organism is suspected, a peptide nucleic acid probe (PNA) FISH can be used to identify the organism directly from the specimen. Which of the following microscopes can be used to exam PNA FISH slides?

Fluorescent microscope

Which of the following conditions is associated with a typical Bacillus cereus infection?

Food borne enteritis

Which of the following statements represents alpha hemolysis on 5% sheep blood agar?

Green area around bacteria; incomplete hemolysis

Which one of the following organisms is sensitive to bacitracin:

Group A Streptococcus

A positive CAMP reaction and hippurate hydrolysis are key in identifying which beta-hemolytic streptococci?

Group B

A ß-hemolytic isolate on SBA revealed a Gram-positive cocci arranged in chains. The isolate was catalase negative, PYR negative, bacitracin resistant, and positive for CAMP and hippurate hydrolysis. What is the presumptive identification of this isolate?

Group B streptococci

All of the following statements about blood cultures are correct EXCEPT?

If two separate sets (two bottles each set) of blood cultures are requested, draw them both from the same site at the same time.

Procedures that may enhance the recovery of Streptococcus pyogenes from throat cultures include:

Incorporation of sulfamethoxazole and trimethoprim in the culture media

Corynebacterium jeikeium is often associated with which of the following conditions?

Infected indwelling devices in AIDS patients

Streptococcus pneumoniae can be isolated from peritoneal fluid and identified by molecular testing. One method of testing used to identify Streptococcus pneumoniae is molecular hybridization. All of the following steps must be followed to ensure that false positive results do not occur when testing for Streptococcus pneumoniae EXCEPT?

Inhibitors must be removed

A beta-hemolytic gram-positive cocci, isolated from the CSF of an infant, grew on sheep blood agar under aerobic conditions and was resistant to a bacitracin disc. Which of the following tests should be performed for the presumptive identification of the organism?

Latex agglutination test

In an urinalysis, tests are performed that serve as a method of screening for urinary tract infections. Which of following tests detects the presence of inflammatory cells?

Leukocyte esterase test

A tech is interpreting a urine culture from a catheter as the source. There is 1 colony of Staphylococcus epidermidis present on the blood agar which was streaked with a 0.001 loop. What should the tech do next?

List S. epidermidis as a possible contaminant

An organism isolated from the spinal fluid of a newborn produced small, grayish, slightly translucent beta-hemolytic colonies on sheep blood agar. A Gram stain of the colony showed small Gram-positive rods that look like diphtheroids. The organism is MOST likely:

Listeria monocytogenes

Which of the following substances produced by Group A Streptococci is responsible for producing type specific immunity?

M antigen

All of the following are virulence factors utilized by Streptococcus pneumoniae to evade host defenses when causing meningitis, EXCEPT:

M protein

Pericarditis may occur as a complication from endocarditis caused by Staphylococcus aureus. Virulence mechanisms attributed to the spread of this organism include all of the following EXCEPT:

M protein

Beyond direct detection, what molecular method listed below is being widely used in clinical laboratories across the United States and allows for rapid detection of a bacteria from an isolated colony?

MALDI-TOF

An organism grew out of a spinal shunt. The protocol for growth of this organism is to notify infection control and the public health department. In addition, any health care worker who came in contact with the patient must be treated promptly with antibiotic prophylaxis. Which of the following organisms requires this type of protocol?

Neisseria meningitidis

What virulence factor is not inherent to bacterium?

Production of opsonins

An urinalysis is commonly performed to detect bacteriuria or pyuria. In an urinalysis, tests are performed that serves as a method of screening for urinary tract infections. Which of following tests detect bacteria that produces enzymes to reduce nitrate?

Nitrate reduction test

Which of the following tests would be most useful in the identification of Streptococcus pneumoniae?

Optochin

Which of the following is a rapid latex agglutination method for detecting Methicillin-Resistant Staphylococcus aureus (MRSA)?

PBP2a

Some strains of Group F Strep can carry the group A antigen, potentially leading to a false positive identification of group A, Streptococcus pyogenes. A spot test that is helpful in differentiating these two species and thus preventing a false report is:

Pyrrolidonyl-b-naphthylamide (PYR)

Examine the following test results and identify what action you would take. CAMP: Arrowhead appearance Bacitracin disk: 6mm zone of inhibition PYR: Negative Bile Esculin: Tan appearance, no darkening

Report the isolate as Streptococcus agalactiae

Gram positive cocci isolated from a catheterized urine culture on a 76-year-old male gave the following reactions: Blood agar- creamy, white, opaque colonies with are not hemolytic Catalase- positive Slide coagulase- negative Tube coagulase- negative Novobiocin- susceptible The next action that the medical laboratory professional should take is to:

Report the isolate as coagulase negative staphylococcus

An alpha hemolytic slightly concave isolate from a respiratory specimen gave a zone of inhibition of 18 mm around the optochin disk. What should the next step be?

Report this organism as Streptococcus pneumoniae.

Which of the following Streptococcus spp. exhibits a positive bile solubility test?

S. pneumoniae

A coagulase test should be performed to differentiate between which of the following?

S.aureus and coagulase negative staphylococci

All of the following are usually associated with Group A Beta Strep, EXCEPT?

Scalded Skin Syndrome

A patient is showing signs of an intravenous catheter associated infection. The physician has removed the catheter and sent the catheter tip along with a skin swab of the catheter site to the laboratory for testing. The physician ordered a Gram stain of the skin entry site and a culture of the catheter tip. On which of the following media should the catheter tip be plated?

Sheep Blood Agar and Thioglycollate Broth

Which of the following Staphylococcus species will produce yellow colonies on mannitol salt agar?

Staphylococcus aureus

Which of the following organisms is both a transient colonizer of skin, as well as the most common cause of bacterial skin infections?

Staphylococcus aureus

Which of these organisms is associated with the condition known as toxic shock syndrome?

Staphylococcus aureus

A Staphylococcus species recovered from a blood culture was found to produce acid from sucrose and maltose and showed alkaline phosphatase activity. The Staphylococcus was also coagulase negative. The same organism was also found in a culture from the central line tip. The most likely identification is:

Staphylococcus epidermidis

A body fluid was sent to the microbiology laboratory for culture and after 48 hours of non-CO2 incubation, a small catalase positive, coagulase negative, Gram positive cocci in clusters grew on sheep blood agar. This organism was considered to be a possible contaminate, since this organism is part of the normal skin microbiota. Which of the following organisms grew in the body fluid?

Staphylococcus epidermidis

Each of the bacterial species listed below may be associated with culture-negative endocarditis EXCEPT:

Staphylococcus epidermidis

Out of the given choices below, which one of the following bacteria is the MOST frequent cause of prosthetic heart valve infections occurring after heart surgery?

Staphylococcus epidermidis

Which of the following is the most common etiologic agent identified in prosthetic valve endocarditis?

Staphylococcus epidermidis

All of the following organisms have capsular material as a defense mechanism EXCEPT:

Staphylococcus saprophyticus

Which of the following urine specimens is a method of collection for uncontaminated urine from the bladder in uncooperative patients or patients unable to void due to physiologic conditions?

Straight Catheterized Urine

A presumptive identification of a bacterial species can often be made by observing the type of hemolysis when grown on 5% sheep blood agar. Which of the following organisms is nearly always alpha hemolytic?

Streptococcus pneumoniae

The most frequent cause of bacterial meningitis in adults and in children is:

Streptococcus pneumoniae

The optochin (ethylhydrocupreine hydrochloride) disk is most often used for the identification of which organism?

Streptococcus pneumoniae

Which of the following organisms is the leading cause of bacterial meningitis in infants, young children, and adults in the United States?

Streptococcus pneumoniae

Which of the following organisms typically produces umbilicate (depressed center, concave) colonies?

Streptococcus pneumoniae

Which organism is associated with sinusitis and otitis and is also considered a leading cause of meningitis with or without bacteremia?

Streptococcus pneumoniae

With the widespread use of the pneumococcal vaccine, there has been a decline in the incidence of community-acquired pneumonia by which of the following organisms?

Streptococcus pneumoniae

The ability of streptococci to spread within the tissues and cause rapidly advancing cellulitis is due to the production of several virulence factors. Each of the following correctly describes the effects of the specific virulence factor EXCEPT:

Streptolysin S is associated with the rash of scarlet fever and the pathogenesis of streptococcal toxic shock like syndrome.

A urine specimen, from a premature infant, was sent for culture to the microbiology laboratory and it grew out 30,000 cfu/mL of a coagulase negative staphylococcus. The physician felt that the growth was skin contamination as the urine was collected in a U-Bag that was attached around the infant's genitalia area. The physician sent a second specimen for culture and it was reported as no growth after 48 hours. Which of the following specimens is the most probable specimen type for the second specimen that was sent to the microbiology laboratory for culture?

Suprapubic Bladder Aspiration Urine

A patient came into the emergency department with a swollen knee and the physician drained 20 mL of fluid from the patient's knee. What is the name of the fluid collected?

Synovial fluid

If septic arthritis is suspected, specimens from which of the following normally sterile sites should be collected to detect the microorganism causing the condition?

Synovial fluid

An expectorated sputum specimen is received for culture at your laboratory. You are preparing to make slides and inoculate the media and are observing the gross appearance of the specimen. The specimen is a mixture of watery, bloody, and purulent material. Which area(s) of the specimen is most likely indicated for culture and slides?

The bloody and purulent areas of the specimen are most indicated for culture and slide preparation.

A urine culture and sensitivity (C&S) specimen is collected at 8 AM at an outpatient clinic and the courier will not be able to pick it up until 2 PM that same day. If refrigeration is not available, how should the specimen be stored until testing is performed?

The specimen should be placed in a container with the proper preservative.

Organisms such as coagulase-negative Staphylococcus, Corynebacterium, and alpha streptococcus species are all found on the skin and represent normal skin flora. All of the following are functions of normal skin flora EXCEPT?

They aid in the transmission of nosocomial infections

A purulent fluid was collected between the lung and the chest wall. What is the name of this fluid?

Thoracentesis fluid

A thoracentesis specimen was collected and sent to the laboratory for testing. What body area was this specimen collected?

Thorax

A methicillin-resistant Staphylococcus aureus was recovered from a wound infection. Which antibiotic would be used for treatment?

Vancomycin