2016.1.Microbiology

An aerobic gram negative coccobacillus was isolated from a nasopharyngeal swab 48 hours after culture from a 6 month old with the following culture characteristics on Bordet-Gengou agar: Small zones of beta-hemolysis Urease: positive Oxidase: negative Motility: negative The MOST probable identification of this isolate is:

Bordetella parapertussis

A gram-negative coccobacillus produced small gray colony surrounded by a zone of hemolysis on potato-blood-glycerol agar. The organism also grew on chocolate agar but NOT on sheep blood agar. The organism is MOST likely:

Bordetella pertussis

A 33 year old farmer, native of central Illinois, gave a one month history of diurnal fever, peaking at in the evening and during the night, but subsiding during the daytime. He also complained of muscle aches and easy fatigability. After several negative blood cultures, an organism was finally recovered after 9 days incubation. The colonies shown in the upper photograph appeared on chocolate agar after 48 hours incubation in CO2. Growth was poor on blood agar. The microscopic morphology of a gram stain prepared from one of the colonies is shown in the lower photomicrograph. The most likely identification is:

Brucella abortis

Match the names of the Corynebacterium species listed with its most likely associated infection or clinical syndrome.

C. xerosis/striatum complex - Acanthamoeba-associated contact lens keratitis C. minitissmum - Erythrasma C. ulcerans - Toxic diphtheria-like pharyngitis C. pseudotuberculosis - Suppurative granulomatous lymphadenitis

Polymerase chain reaction (PCR) copies DNA through repeated cycles of three basic steps. What is the correct order of these steps? (Choose the BEST answer)

Denaturation, annealing, and synthesis at 72°C

Asaccharolytic use of glucose would be indicated by which reaction in OF glucose tubes:

Green in both tubes with a little blue at the top of the open tube

A 30 year old man with chronic persistent hepatitis developed an abscess in the right hepatic lobe. A needle aspiration revealed purulent material. The small colonies shown in the upper photograph were isolated after 36 hours incubation at 35°C. They emitted a butter scotch odor. The lower photomicrograph reveals the gram stain features. The antigen most likely carried by this isolate is:

Group F

Way down under in Brazil, Fever and rash I cause at will.

Haemophilus aegyptius

Look, oh look at the little red dot, Tell me, O tell me, who I am not.

Haemophilus influenzae

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)

A mixture of Gram positive and Gram negative bacteria may be present within the same field of a slide.

True

Streptococcus pneumoniae is the most common cause of fatal community-acquired pneumonia.

True

Illustrated in this photograph is an agar plate on which an unknown species has been inoculated. A 5ug novobiocin disk, a 100ug furazolidone disk, and a 0.04ug bacitracin ("A") disk had been applied immediately after inoculation of the plate. Based on the pattern of the zones of inhibition to these three antibiotics, the most likely identification is:

Micrococcus luteus

A patient with an upper respiratory infection submits a sputum for culture. A Gram stain performed on the sputum specimen reveals gram-negative diplococci. Oxidase testing is positive and carbohydrate degradation tests are inactive. The organism may presumptively be identified as:

Moraxella catarrhalis

Match the name of the Mycobacterium species listed with its most likely associated disease presentation as illustrated in the photographs.

Mycobacterium avium/intracellulare - Upper Left (GI biopsy) Mycobacterium marinum - Upper Right (subcutaneous skin infections) Mycobacterium tuberculosis - Lower Left (upper lobes of lungs) Mycobacterium scrofulaceum - Lower Right (cervical lymph nodes)

Match the names of each of the fungi listed with its appropriate category indicating the degree of pathogenicity.

Usually not pathogenic Alternaria species Usually pathogenic Fonsecaea pedrosoi Usually pathogenic Phialophora verrucosa Usually not pathogenic Bipolaris species

The end product of the fermentative metabolism that characterizes members of the Enterobacteriaceae is:

Various mixed acids

Which one of the following tests would be positive in the presence of Klebsiella:

Voges-Proskauer test

This isolate is a catalase negative, gram positive coccus on sheep blood agar. The P disk has 5µg of optochin and the zone around it is 16 mm. It has been streaked perpendicular to a beta lysine-producing Staphylococcus aureus. The presumptive identification is:

Streptococcus pneumoniae

Select the morphologic structure that identifies Candida albicans and distinguishes it from most other Candida species.

chlamydospore

Which of the following shapes can be used to describe cocci?

ovoid lancet round

Which of the following is not considered a potentially infectious body fluid for transmitting HIV?

sweat

Moving forward, important strategies for dealing with MRSA strains will include the following:

1. Antimicrobial stewardship to guide the use of both existing alternatives and newer drugs. 2. Identification of MRSA strains in all settings (inpatient as well as outpatient). 3. Possible development of vaccines. All of the above.

Match the illustrations with their correct description:

A- Monotrichous B- Peritrichous C- Amphitrichous

Which two of the following tests are helpful for documenting previous Streptococcal throat and skin infections:

ASO titer Anti-DNase B

A 40 year old man with a prosthetic valve developed intermittent bouts of low grade fever. A changing cardiac murmur suggested the possibility of endocarditis; however, repeat blood cultures over a two week period were all negative. Bacteria resembling those seen in the lower photomicrograph were finally seen in gram stain of a positive bottle. Colonies were recovered when broth was subcultured to a blood agar plate with a staph streak, as shown in the upper photograph. The most likely bacterial species is:

Abiotrophia defectiva

A 36-year old woman is a known intravenous drug abuser, and gives a history of "several previous episodes of hepatitis". The laboratory workup is as follows: HBsAg- Reactive anti-HBs- Negative anti-HBc- Total Positive anti-HBc IgM- Negative anti-HAV- Total Positive anti-HCV- Positive anti-HAV IgM- Negative Which of the following diagnoses can be excluded based on laboratory data and current symptoms and history?

Acute hepatitis A

Which nitrogenous base would bind with thymine in forming double-stranded DNA?

Adenine

The colonies growing on the surface of this 5% sheep blood agar plate were recovered from a throat swab of a 19 year old girl with acute pharyngitis. The visual identification was Streptococcus pyogenes. Surprise! Gram stain revealed club-shaped gram positive bacilli with rudimentary branching. Of the bacterial species listed, the most probably identification is:

Arcanobacterium hemolyticum

Orthonitrophenyl-b-D-galactopyranosidase (ONPG) is produced by several bacterial species. It acts by cleaving the beta galactosidase bond of certain disaccharides, such as lactose. An ONPG-positive bacterial species, however, may appear as a "late lactose user" because of the absence of:

B-galactoside permease

The name of the rapid test seen in the image, often used to differentiate S. pneumoniae from viridans streptococci, in which a drop of 10% deoxycholate was placed on an area of growth, is:

Bile solubility

Each of the following bacterial species are commonly associated with wound infections following a dog bite except:

Bordetella bronchicanis

Match the names of the bacterial species listed into Bucket A if it produces only a small amount of H2S along the streak line in an SIM tube; or into Bucket B if it produces large amounts of H2S, turning the butt a diffuse black.

Bucket A - Salmonella typhi Bucket B - Proteus mirabilis Bucket B - Salmonella typhimurium Bucket A - Erysipelothrix rhusiopathiae

Surprise! Animals are not the only creatures infected with bacteria. The bacterial species causing onion rot is:

Burkholderia cepacia

Which of the following organisms causes thrush:

Candida albicans

Various methods have been employed for detection of C. difficile disease: cultivation of the organism, cell cytotoxin neutralization assays, and enzyme immunoassays have all been among the staples of diagnostic approaches. Which statements are accurate characterizations of these assays?

Cell culture based cytotoxin neutralization assays provide definitive detection of toxin-producing C. difficile strains. Enzyme immunoassays detecting both Toxin A and Toxin B allow the detection of more strains of C. difficile and are therefore preferred over assays that detect only Toxin A.

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

Charcoal and yeast extract

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

Chocolate agar

The tendency for the mycobacterial cells of M. tuberculosis to assemble in linear aggregates as seen in this photomicrograph of an acid-fast stained preparation is caused by production of:

Cording factor

This member of the Enterobacteriaceae was isolated from a stool specimen and gave the following biochemical reactions: TSIA . .. . . . . . .K/A, no gas, no H2S Citrate . . . . . . . Positive Lysine . . . . . . . .Negative Ornithine. . . . . . .Positive Indole. . . . . . . . . Negative This organism agglutinated in Group D Shigella antiserum. Which biochemical result is NOT consistent with this identification?

Citrate

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

Clostridium perfringens

Although care should be taken when working with all fungus cultures in the laboratory, personnel are particularly prone to develop laboratory acquired infections from the inhalation of airborne species of:

Coccidioides immitis

The ingredient added to culture media to enhance the recovery of the dimorphic fungi by preventing the overgrowth of more rapidly growing, saprophytic molds is:

Cycloheximide

The historical medium of choice for isolation of Francisella is:

Cysteine Blood Glucose Agar

The diagnosis of diphtheria must be confirmed by:

Determining that a culture isolate is a toxin producing strain

Loeffler's serum medium is useful in making the presumptive identification of isolates suspicious for Corynebacterium diphtheriae recovered from oropharyngeal cultures because it:

Enhances granule formation as seen in methylene blue stains

I measure 15 micro meters and am found in stool.

Entamoeba histolytica cyst

Match the viruses below with their associated diseases.

Epstein-Barr - Infectious mononucleosis Varicella-Zoster - Chicken pox Rhabdovirus - Rabies Picornavirus - Polio

Among the gram-positive bacilli, the unique species producing H2S as seen in the Kligler Iron Agar slant illustrated in this photograph is:

Erysipelothrix rhusiopathiae

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

Exfoliative toxin and enterotoxins Natural colonization/reservoir for infection Hyaluronidase

Which of the following is a confirmatory test for syphilis:

FTA-ABS

A 25-year-old female presented in the emergency room with an acute urethral discharge of two days duration. The image to the right shows the Gram stained smear that was obtained. Many polymorphonuclear leukocytes and intracellular and extracellular gram-negative diplococci were observed. Based on the clinical history and the Gram stain observation, a diagnosis of gonorrhea can be made.

False

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

Fermentation of glucose

Extraction of the inoculated and incubated tryptophane broth with xylene and the use of Ehrlich's reagent are necessary steps in the detection of indole production by:

Flavobacterium (Chryseobacterium) indologenes

Which one of the following would NOT be suitable for identification of bacterial antigens?

Gram Stain Reactions

Large, one-celled, smooth-to-tuberculate macroconidia, and smooth or echinulate microconidia are typical of mycelial phase growth of which organism?

Histoplasma capsulatum

Of the dimorphic fungal species that are listed below, the one with the longest time of recovery in primary culture is:

Histoplasma capsulatum

Which one of the following statements about blood cultures is NOT correct?

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

The bacterial species commonly causing bronchopneumonia in foals, that can cause a slowly progressive tuberculosis-like pulmonary infection in humans is:

Rhodococcus equi

The colonies growing on the surface of a thiosulfate citrate bile sucrose (TCBS) agar plate (the green color indicates lack of sucrose fermentation) were identified as Vibrio vulnificus. The serious complication of infections with this bacterial species is:

Life-threatening septicemia

What is the MOST likely identification of an acid-fast bacillus that demonstrates the following characteristics? slow growth cream to tan colored colonies when grown in the dark development of yellow pigment upon exposure to light

Mycobacterium kansasii

What is the MOST likely identity of an acid-fast bacilli that showed buff colored, dry, heaped colonies; niacin, nitrate, and urease positive; and took 23 days at 35ºC to grow?

Mycobacterium tuberculosis

The growth seen here on PPLO agar is most likely caused by:

Mycoplasma

A cell wall deficient bacterium that commonly causes atypical or "walking pneumonia" is:

Mycoplasma pneumoniae

Image: The streptococci and related organisms can cause a variety of infections. Match each of the clinical manifestations of streptococcal diseases listed with the corresponding photograph that illustrates the identifying characteristic of the associated bacterial agent for each.

Neonatal meningitis A Lobar pneumonia B Acute pharyngitis C Acute cystitis D

Nitrate reduction is the process by which nitrate is reduced to nitrite; in denitrification, nitrate is completely reduced to nitrogen gas. Match the name of each of the bacterial species listed below into the appropriate bucket indicating whether it reduces or denitrifies nitrate.

Nitrate reduction - Yersinia enterocolitica Denitrification - Pseudomonas aeruginosa Nitrate reduction - Citrobacter amelonaticus Denitrification - Pseudomonas stutzeri

For each of the laboratory tests listed, match the name of the chemical reagent listed that is responsible for the positive end color reaction.

Nitrate reduction - alpha naphthalamine Voges Proskauer - alpha naphthol Indole - dimenthylaminobenzaldehyde Phenylalanine deaminase - ferric chloride

A sputum sample from a patient with pulmonary abscesses is received in the laboratory, and after several days of incubation the following are noted: Yellow, irregular colonies grow on BAP under aerobic conditions. Acid-fast stain shows that the organisms are partially acid-fast. Which of the following organisms should be suspected?

Nocardia asteroides

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

Propionibacterium acnes

The definitions listed below define terms that are used in molecular testing. Match each definition to the term from the drop-down box that it defines.

Oligonucleotide - A short synthetic strand of nucleic acid Probe - A fragment of nucleic acid that is complementary to another nucleic acid sequence; it is labeled and used to identify the complementary sequence. Target - A specific region of DNA or RNA unique to the organism, mutation, or disease that is detected by the molecular testing method

The photograph is of a 5% sheep blood agar plate inoculated with a throat culture. It is common practice to stab the agar with the inoculating needle, as seen at the tip of the arrow, in order to detect or accentuate the reaction of:

Oxygen labile hemolysin

Match the names of the organisms listed below in the appropriate bucket indicating whether each more commonly causes gastrointestinal or pulmonary infection.

Pulmonary infection Moraxella catarrhalis Gastrointestinal infection Campylobacter jejuni Pulmonary infection Nocardia asteroides Gastrointestinal infection Aeromonas hydrophila

Which of the following is NOT a possible cause of cell death after HIV infection?

Penetration of the membrane by the HIV spike

The dematiaceous colony illustrated here grew to a diameter of 3 - 4 cm in 5 days. The dematiaceous fungus that can be ruled out is:

Phialophora verrucosum

Which animal was involved in the reassortment of influenza A viruses that led to the 2009 novel influenza A H1N1 virus?

Pigs

The condition most likely to predispose a person to septicemia by viridans streptococci is:

Poor oral hygiene

The bacterial species producing the swarming on the surface of the 5% sheep blood agar plate shown in the photograph was indole negative. The most likely identification is:

Proteus mirabilis

On sheep blood agar Haemophilus influenzae may exhibit satellite formation around all but which of the following organisms:

Pseudomonas

This Gram-positive coccus is catalase positive. The tests below are a tube coagulase test where rabbit plasma is inoculated with the isolate and a plate containing 4% NaCl and 6µg/mL of oxacillin. A 0.5 McFarland standardized inoculums of the isolate is inoculated to the plate. What step should you take next?

Report the isolate as methicillin resistant Staphylococcus aureus.

Which of these laboratory methods are recommended for confirmation of influenza A H1N1 subtype infection?

Reverse transcriptase-polymerase chain reaction (RT-PCR)

Anthrax, tuberculosis, and cholera, Years and years of toil and bother, Royal reception by the Chancellor, Forever acclaimed the "Bacillus Father".

Robert Koch

Public health guidelines recommend that laboratory specimens for influenza testing must be manipulated using which of the following safety precautions?

Safety cabinet

Match the names of each of the bacterial species listed with the creatures listed that may serve as a reservoir for potential infections in humans.

Salmonella enteritidis - Poultry Escherichia blattae - Cockroaches Edwardsiella tarda - Reptiles Yersinia pestis - Rats and other rodents

This member of the Enterobacteriaceae is shown on triple sugar iron agar, lysine iron agar, urea agar, citrate agar , phenylanine deaminase agar, and motility indole ornithine agar. It should be identified as:

Salmonella spp.

Match the names of each of the bacterial species listed with its most likely appearance on the agar plates illustrated in the photographs. Image A is xylose-lysine- deoxycholate (XLD) agar, Images B and C are Hektoen Enteric (HE) agar, and Image D is DNA agar.

Salmonella typhimurium A Morganella morganii B Enterobacter cloaecae C Serratia marcescens D

Match the name of each of the bacterial species listed with its most likely gram staining features as illustrated in the photographs.

Staphylococcus epidermidis A Viridans streptococcus B Streptococcus pneumoniae C Enterococcus faecalis D

A 30 year old laboratory worker doing extensive research on laboratory mice developed sudden onset of fever, chills, headache and muscle aches. He remembered being bitten by one of the mice about a week previously, although the skin wound healed without incidence. The gram stain preparation illustrated in the photomicrograph is representative of the organism recovered from blood cultures.

Streptobacillus moniliformis

The ability of streptococci to spread within the tissues and cause rapidly advancing cellulitis is due to the production of several virulence factors. Match each of the virulence factors with its specific manifestation.

Streptokinase - Hydrolysis of fibrin clots Streptolysin S - Leucotoxic killing of phagocytes Pyrogenic exotoxins - Scarlet fever rash Hyaluronidase - Depolymerization of ground substance in connective tissue

The bacterial species most likely giving the reactions seen in the casein (A), tyrosine (B) urase (C) and xanthine (D) agar segments of this quadrant plate is:

Streptomyces griseus

Nocardia farcinica has been distinguished from other members of the Nocardia asteroides complex because most strains are resistant to erythromycin and other antibiotics commonly used to treat nocardia infections, and are more commonly recovered from patients with severe underlying illness. Characteristics that are helpful in the preliminary identification of this species include:

The ability to grow at 45°C A white opacity around colonies on Middlebrook agar

Humans become infected with sylvatic plague by:

The bites of rat fleas

What is the source of the HIV envelope?

The host cell membrane

Match the names of the organisms listed with the appropriate bucket indicating whether each more commonly causes clinical disease via toxin production or via direct invasion.

Toxic infection Clostridium botulinum Toxic infection Vibrio cholerae Invasive infection Yersinia enterocolitica Toxic infection Shigella sonnei

What organism causes White Piedra which infects hairs on the face, scalp, and body areas?

Trichosporon beigelii

Match the differential/ selective enteric medium with its characteristic indicator, fermentable, and bacteriostatic.

Xylose-lysine-deoxycholate - phenol red, lactose, bile salts Eosin methylene blue - eosin Y and methylene blue, lactose, eosin Y and methylene blue Bismuth sulfite - bismuth sulfite, glucose, brilliant green Salmonella-shigella - neutral red, lactose, bile salts

A small portion of colonial growth of an unknown bacterial species was inoculated to the surface of a filter paper strip impregnated with cytochrome oxidase reagent (dimethyl-p-phenylenediamine dihydrochloride). The family of bacteria ruled out by the reaction seen in the photograph is the:

Enterobacteriaceae

A D test is performed on Gram-positive cocci to determine inducible resistance to clindamycin when the isolate is resistant to:

Erythromycin

Which one of the following organisms is typically urease negative:

Escherichia

A 21 year old female developed painful swelling of the left knee associated with low grade fever. The knee was painful to palpation, an effusion was evident and the overlying skin was slightly erythematous. Fluid was aspirated and a direct gram stain was performed (see photomicrograph). Based on the gram stain morphology, each of the following bacterial species could serve as the etiologic agent in the case described except:

Haemophilus influenzae

Match the names of the Mycobacterium species listed with the appropriate bucket indicating whether it is a photochromogen or a scotochromogen.

Scotochromogen - Mycobacterium scrofulaceum Photochromogen - Mycobacterium marinum Photochromogen - Mycobacterium kansasii Scotochromogen - Mycobacterium flavescens