Micro Practicum

A beta-hemolytic Streptococcus was isolated from a throat culture. It gave the following biochemical reactions: Bacitracin - Susceptible Bile esculin - Negative 6.5% NaCl - No growth CAMP - Negative SXT - Resistant What is the presumptive identification?

Beta hemolytic Streptococcus, Group A

What organism causes relapsing fever?

Borrelia recurrentis

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

Cefoxitin

Which of the culture media listed is selective for the isolation of Yersinia enterocolitica in stool samples?

Cefsulodin-Irgasan-Novobiocin (CIN)

In the image to the right, the letter B represents what type of endospore placement?

Central

This artifact, when seen, is indicative of intestinal inflammation and is characteristic of a number of parasitic infections is known as (a):

Charcot-Leyden crystal

Based on the reactions observed in the tubes shown in the photograph (including open and closed OF dextrose and a positive nitrate reaction only after the addition of zinc dust, as shown in the right tube of the pair labeled "Nit"), the most likely identification is:

Chryseobacterium spp

a patient diagnosed with B. anthrasis is allergic to penicillin. Which antibiotic can be given that will be therapeutically effective?

Ciprofloxacin

Review the image provided The presence of this organism tissue sample suggests

Clostridium spp

From the following organisms, which one is considered to be the LEAST pathogenic to humans?

Corynebacterium ulcerans

Agar plates on a positive blood culture are incubated for 48 hours and no growth is visible on the agar plates. The tech reviews the initial Gram stain from the blood culture bottle, which reveals tiny pleomorphic Gram-negative coccobacilli. What organism should the tech suspect and what should the tech do next?

Francisella tularensis; Sub blood culture bottle to a media with cysteine for optimal growth

Which organism is nonhemolytic on 5% sheep's blood agar but hemolytic on human blood?

G. vaginalis

Which of the following would be the most appropriate temperature for long term storage of specimens for viral culture?

-70° C

A clean catch urine specimen was streaked to a sheep blood agar plate and a MacConkey plate with one microliter (0.001 mL) loop. The images to the right demonstrate the observed growth. How would you report the colony count and growth?

103 CFU/mL of a gram-negative bacillus

Which of the following HPV types are most likely to be associated with cervical cancer?

16 & 18

When collecting specimens for viral studies, samples should be collected within how many days of the onset of symptoms for best sensitivity?

2-3 days

Media that can be used for isolating Bacillus anthrocis include:

5% sheeps blood agar

Illustrated in the image to the left are 3-day old colonies growing on blood agar. The colonies are gray and spreading, and a sweet, fruity odor is noted. Plump, Gram-negative coccobacilli are seen on Gram stain. This isolate belongs to the motile, non-fermenters with peritrichous flagella. Carbohydrate utilization is asaccharolytic. Nitrite reduction produces gas and citrate is positive. From the multiple choices, select the name of this isolate.

Alcaligenes faecalis

Binary fission is the means of reproduction for which of the following groups of parasites?

Amebae

This suspicious form was recovered from a bone marrow biopsy and measures 4 µm in length. What is the MOST likely identification of this organism?

Leishmania amastigote

Animal inoculation may be used to identify all of the following conditions except:

Malaria

This Gram stain was prepared from a lower respiratory tract specimen. How should this Gram stain be reported?

Many gram-positive cocci in pairs, many polymorphonuclear white blood cells (PMNs)

Which of the following has been compared to a hockey puck when discussing its morphology on chocolate agar?

Moraxella catarrhalis

A CLS is reading CTA sugars. The maltose and glucose tubes are positive. what organism produces acid in these two tubes

N. meningitis

Multiple ring forms in red blood cells are most frequently seen in which Plasmodium species infection?

P. falciparum

Which of the following methods combines nucleic acid amplification testing and mass spectrometry (MS) for ID of S. aureus and MRSA?

PCR/ESI-MS

A 38-year-old male presented to the E.R. complaining of severe cough, chest pain, shortness of breath, and fatigue. Microscopic examination of a bloody sputum specimen revealed this suspicious form. The patient is most likely suffering from:

Paragonimus westermani

The picture best represents which of the following:

Plasmodium ring form

This suspicious form was seen on a peripheral blood smear. The most likely identification is:

Plasmodium schizont

Parasitized animals that may serve as a source of infection for humans are called:

Reservoir hosts

Which laboratory method is recommended for confirmation of an Influenza A H1N1 subtype infection?

Reverse transcriptase-polymerase chain reaction (RT-PCR)

Common colds are most often associated with which agent?

Rhinovirus

The specimen of Staphylococcus, which is one of the most important human pathogens, is:

S aureus

the bacterial species that can be described as able to hydrolyze Hippurate, is B-hemolytic, is a major cause of neonatal meningitis and sepsis, and is a producer of the Christie, Adkins, Munch-Peterson (CAMP) factor is:

S. agalactiae

Erythrogenic toxin, hyaluronidase enzyme and hemolytic S and O are extracellular products of:

S. pyogenes

Which species of bacteria is responsible for causing diseases such as rheumatic fever, glomerulonephritis and exudative pharyngitis?

S. pyogenes

An infected intravenous (IV) catheter tip grew out gram-positive cocci, which were catalase positive and coagulase negative. The zone size of the novobiocin disk measured 18 mm. The most likely organism causing infection is:

S. saprophyticus

Which of the following is the ideal method for processing wound swab specimens for a Gram stain and culture?

Specimen should be collected on a single swab that will be placed in 1.0 mL of saline and vortexed. The saline solution should then be used to inoculate all media and prepare the smear.

In a HPV infection, where does the viral DNA replicate?

Squamous epithelial cells

The tech in microbiology receives a call from the outpatient center where the doctor wants to test a patient's wound to determine if is caused by cutaneous anthrax. What should the tech indicate is a proper specimen for collection to detect cutaneous anthrax?

Swab under the edge of the skin

All of the following pose a significant risk of transmitting bloodborne pathogens, EXCEPT?

Sweat

Illustrated in this image is a single proglottid representative of one of the cestode tapeworms. This proglottid is longer than wide and has well over 13 lateral uterine branches. Select the presumptive identification of this tapeworm.

Taenia saginata

Sulfonamides, such as sulfamethoxazole (SMZ), and trimethoprim (TMP), work by targeting:

Tetrahydrofolate synthesis; preventing bacterial DNA synthesis

At an outpatient clinic, a patient comes in with an order for stool ova and parasites (O & P). How should this specimen be collected and transported for the best test results?

The specimen should be immediately placed in recipients containing polyvinyl alcohol (PVA) or formalin and transported to the laboratory.

All of the following are true about all members of the Enterobacteriaceae, EXCEPT:

They are all oxidase positive

A small gram-negative rod isolated from an eye grows on chocolate agar and it produces satellite growth around staphylococci colonies on sheep blood agar. The organism requires:

X and V factor

A Gram negative rod exhibiting bipolar staining was isolated from sheep blood agar after 24 hours of incubation. Oxidase-Negative Urease-Negative Catalase-Positive Indole-Negative Which of the following species is most probable?

Yersinia pestis

A chronic, granulomatous infection of subcutaneous tissues, which is caused by aerobic actinomycetes resulting in tissue swelling and draining sinus tract, is referred to as:

actinomycetoma

A pharyngeal specimen is inoculated on cystine-tellurite blood agar, modified Tinsdale agar and MacConkey agar. After 48 hrs of incubation, black colonies with a brown growth is observed on the MacConkey agar. What explains the discrepancy?

no discrepancy present. this organism does not grow on MacConkey

What is one of the BIGGEST challenges with isolating Francisella?

organism is slow to grow

All of the following patients may submit an urine specimen from an indwelling catheter EXCEPT?

patient seen for annual physical

A tube coagulase test was performed on catalase positive, gram positive cocci that were B-hemolytic and grew on mannitol salt agar. The tube was checked after overnight incubation and was negative. What explains this discrepancy

the test should have been read in 1-4 hours in case any hemolysins are present

All of the following choices are acceptable specimens for anaerobic culture, EXCEPT?

throat swab

This microscopic field is representative of other fields that were observed on a Gram-stained smear. Which of the following describes the quality of the smear?

under-decolorized; poor quality

The urease reaction seen in the Christensen's urea agar slant on the far right indicates:

weak activity

All of the following are examples of preanalytic errors, EXCEPT:

wrong test performed

A microbiologist performed a Gram stain procedure on a sputum specimen and was unable to determine if what was seen on the smear were tiny, Gram-negative organisms or stain debris. Which of the following stains would help the microbiologist make a correct determination?

Acridine orange

Which statement about bacterial culture for Clostridioides (Clostridium) difficile is TRUE?

Culture on appropriate media provides an effective means of recovering the organism.

An anaerobe was recovered from a blood culture after 92 hours of incubation. A gram stain of the isolate is illustrated in the photomicrograph. The most likely identification is:

Cutibacterium (propionibacterium) acnes

Illustrated in the upper image is an H & E stained section of a cyst of the brain observed in an autopsy case. Shown is the thin cyst lining from which secondary cysts, called "brood capsules", are derived. Upon maturation, small oval buds develop within the brood capsules and produce protoscolices known as "hydatid sand" as illustrated in the lower image. These are the anlagen of the adult Taenia solium tapeworm. From the multiple-choice list, select the clinical disease represented by this developing cyst.

Cysticercosis

All of the following are roles of a sentinel microbiology laboratory, EXCEPT?

Determine that a bioterrorist event has occurred.

All of the following parasites may typically survive human stomach juices except:

Entamoeba gingivalis trophozoite

This cestode is commonly associated with dogs and cats but may also be transmitted to humans through the ingestion of dog and cat fleas that contain the cysticercoid stage of the parasite. Laboratory diagnosis may be made by observing groups of egg packets, as seen in the diagram, in the stool

Dipylidium caninum

Which of the following statements is true regarding the various non-molecular methods used for influenza testing?

Direct fluorescent antibody (DFA) staining on specimen smears can provide rapid results but are dependent on the availability of trained personnel to accurately interpret the smears.

Acceptable sources for urine culture from a patient with suspected urinary tract infection include all EXCEPT:

Drainage bag from nephrostomy catheter

The Carba NP confirmatory test is used to detect all of the following carbapenemases EXCEPT?

ESBL (Extended Spectrum Beta-Lactamase)

What cestode, pictured here, resides in multiple tissues of the human body

Echinococcus granulosus

The term "hydatid sand" is used in reference to which of the following tapeworms?

Echinococcus species

The 6 µm in diameter trichrome-stained cyst illustrated in this photomicrograph was inadvertently observed in a stool specimen that was being examined for reasons not clinically related to parasitic diseases. Further history revealed that the patient for whom the stool examination was being performed, had only rare bouts of mild diarrhea. Based on the characteristics in the illustration and the patient information, the most likely identification is:

Entamoeba hartmanni

This trichrome-stained organism measuring 15 µm was found in a stool sample. What is the identification of this parasite?

Entamoeba histolytica

Which of the following viruses requires a complex lymphoblastoid cell culture, and is rarely, if ever, diagnosed by culture?

Epstein-Barr Virus

Illustrated in this image is a large adult trematode averaging 3 - 7 cm. This fluke resides primarily in the small intestine. Characteristic is the rounded cephalic end, the convoluted uterus in the anterior half of the fluke, and delicate branching testes in the posterior half. Humans become infected by ingesting metacercaria contaminated water vegetables. Select the presumptive identification

Fasciolopsis/Fasciola species

The adult form that produces this 140 µm x 75 µm egg, typically inhabits the small intestine or bile ducts. What is the identification of this organism(s)?

Fasciolopsis/Fasciola species

The staining reaction for yeast is:

Gram positive

What is a major reason why there is no viable HIV vaccine available on the market?

HIV has a high mutation rate due to the lack of proofreading ability by reverse transcriptase

Current CDC (2014) recommendations for initial HIV screening include FDA-approved immunoassay for detection of:

HIV-1 and HIV-2 antibody, HIV-1 p24 antigen

Spirochetes compromise all the following EXCEPT?

Helicobacter

Which of the following is a DNA virus?

Hepatitis B virus

Illustrated in the photograph is a high-power view of a 70 µm ovum with a thin, smooth outer shell and an inner membrane containing a hexacanth embryo. This ovum is indigenous primarily in rats and mice and rarely found in human feces but when found, the infected person usually has minimal symptoms. With heavy infections, particularly in those who are immune-suppressed, abdominal pain, diarrhea, and anal pruritis may be experienced. What is the presumptive identification of this ovum?

Hymenolepis diminuta

This suspicious form measures 18 µm and was seen in an ova and parasite exam from a stool concentrate. The most likely identification is:

Iodamoeba butschlii

Which two intestinal protozoans lack peripheral chromatin in their cyst forms?

Iodamoeba bütschlii & Endolimax nana

Amoebae stained with this substance may be readily distinguished because it enhances nuclear and structural detail.

Iodine

A 65 y/o male with type 2 diabetes presented to ED complaining of febrile episodes following his last dialysis treatment. The microscopic examination of his urine showed numerous white blood cells and bacteria. His urine was sent to the laboratory for culture and sensitivity. Urine colony count was >100,000 CFU/mL for a single organism that was identified as Klebsiella pneumoniae. Observe the reactions of this organism on the Kirby Bauer antibiotic susceptibility plate and review the susceptibility results on the AST report form. The Hodge Test was positive. Which resistance mechanism is this organism demonstrating?

KPC - Klebsiella pneumoniae Carbapenemase

Sequence-based analysis is an alternate method used to identify bacteria and fungal isolates. This methodology uses rRNA genes (rDNA) and their intergenic regions as common target sites to identify these organisms. Which of the following rRNA gene target sites is used to identify fungal isolates?

Large Sub-unit (LSU) 28s rRNA

If a positive result for a rapid HIV test is obtained, all of the following are possible next steps EXCEPT:

No additional testing required

Which of the following is the first step in the four steps of Koch's postulates?

Observe the same organism in all cases of a given disease

Which EBV markers would be MOST likely positive for an individual who had infectious mononucleosis nine years ago?

Only anti-VCA (IgG) and anti-Epstein-Barr nuclear antigen (EBNA) are positive.

The adult flukes related to this 100 µm ovum typically inhabit the lung parenchyma; ova are most commonly found in sputum specimens. Diagnostic features for the ovum include a slightly thickened shell with a prominent shouldered operculum (as seen at the left lower end), a developing larva within the shell that is retracting from the inner margin leaving a clear space. Infections with this fluke are endemic in the orient, West Africa, South and Central America, and may be observed in patients who have traveled to one of these regions. Human infection occurs following ingestion of poorly cooked crab meat or crayfish contaminated with metacercariae. Intermittent chest pain and cough with occasional spitting up of blood (hemoptysis) may be experienced after infection. From the choices below, select the trematode species related to this ovum.

Paragonimus westermani

The presence of parasites in human blood is termed:

Parasitemia

The following are all possible causes of cell death in HIV infections, EXCEPT?

Penetration of the membrane by the HIV spike

All of the following antibiotics are used to treat mycoplasma infections EXCEPT ?

Penicillin

Which of the following organisms appear Gram-positive when using the Gram Stain?

Peptostreptococcus anaerobius

Escherichia coli: >100,000 CFU/mL Staphylococcus epidermidis: 5,000 CFU/mL How should the tech continue with the culture workup?

Perform sensitivity on E. coli and list the S. epidermidis as a contaminant

Shown here is a Kligler Iron Agar (KIA) tube with black pigmentation is confined to the butt of the tube. From the multiple choices, select the bacterial species that produces the reaction seen in the lower image of the KIA tube.

Proteus mirabilis

A tech is working on a urine culture and finds the following isolates: Escherichia coli: >100,000 CFU/mL Enterococcus faecalis: 50,000 CFU/mL Klebsiella pneumoniae: 30,000 CFU/mL How should the tech continue with the culture workup?

Quantitate culture and report as mixed urethral flora/contaminants

The core (genome) of the HIV virion contains:

RNA

HIV is known as a retrovirus because

RNA is used as the template for DNA synthesis

HIV is known as a retrovirus because:

RNA is used as the template for DNA synthesis.

Select from the multiple choices the specimen that is inadequate for the recovery of anaerobes and should be summarily rejected upon receipt in the microbiology laboratory.

Uterine cervical swab in Cary-Blair transport medium

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

Vancomycin

All of the following viral causative agent and associated disease state combinations are correct EXCEPT:

Variola Virus: Polio

A cerebrospinal (CSF) cell count is 1000 cells/µL. The cells on differential are predominantly lymphocytes. CSF protein is moderately elevated and the glucose is normal. No microorganisms were observed on a Gram stain smear of the CSF sediment. What is the MOST likely condition?

Viral meningitis

The major etiologic agent of bacterial endocarditis in the united states is:

Viridans streptococcus

From the viruses listed below, select the one that is transmitted from birds to humans through a mosquito vector.

West Nile virus

Illustrated in this photomicrograph is the tail portion of an adult filarial nematode. Human infections with this nematode are more commonly found among those living in Southeast Asia but may be observed in recent travelers there and to surrounding regions. These adult worms measure up to 300 µm, occupy lymphatic channels, and may cause lymphatic obstruction. Varying degrees of fever and chills may be experienced. The species indicated in this exercise by the orientation of nuclei within the tail section (arrows), more commonly involves the lymphatics of the genital tract resulting in orchitis and hydrocele. From the nematodes listed below, indicate the most likely identification.

Wuchereria bancrofti

All of the following are considered a potentially infectious body fluid or a route of transmission for HIV, EXCEPT?

airborne transmission

Which of the following antibiotics inhibits protein synthesis by binding to the 30S ribosomal subunits and provides coverage against Gram-positive and Gram-negative aerobes?

aminoglycosides

The best clinical specimen for the recovery of Legionella pneumophilia is:

bronchial washing

A tech is working with a small Gram-negative coccobacillus that may be Francisella tularensis. Which of the following tests could the tech use to rule out this organism?

catalase negative

The media used to isolate Legionella pneumophilia should contain which of the following additives?

charcoal and yeast extract

Which age group has been most affected by the H1N1 virus?

children

Which of the following media contains the X and V factors necessary for the growth of Haemophilus influenzae?

chocolate agar

The dimorphic molds exist in both mold and yeast forms depending on the temperature of incubation. In the laboratory, when cultures are incubated at 30o C, all of the dimorphic fungi will produce mold colonies, usually within 10 - 14 days. When cultures are incubated at 35o - 37o C, yeast colonies develop usually within 3 - 5 days, with the exception of one of the dimorphic species. From the options shown below, select the genus that does not produce yeast colonies when cultures are incubated at a higher temperature.

coccidioides immitis

Infections with all of the following viruses could cause malignant disease, except:

cytomegalovirus (CMV)

How does the modified acid-fast stain differ from the conventional acid-fast stain?

detergent

When transporting specimens for Mycoplasma culture to the laboratory, extreme care must be taken so that the specimen does not:

dry out

After 48hrs of incubatuon, black colonies with a dark brown halo atr observed on Tinsdale-agar. What type of toxin does this organism

exotoxin

How should the organisms that are indicated by the arrows be reported?

intracellular gram-negative diplococci

Carbapenemases are produced by various organisms such as Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter species. Detecting the presence of carbapenemase activity in these organisms is important to prevent the spreading of resistant organisms. Which of the following methods is used to detect the presence of carbapenemase-producing organisms?

mCIM