Microbiology II Test I Quiz 3

S. agalactiae

A technologist observes large, beta hemolytic colonies growing on the blood agar plate of a vaginal culture on a pregnant woman.  The colonies are translucent with a small zone of beta hemolysis.  A gram stain of the bacteria reveals they are gram positive cocci.  These organisms have the following biochemical characteristics:

catalase = negative hippurate hydrolysis = positive PYR hydrolysis = negative

arginine hydrolysis = positive ribose fermentation = positive Voges-Proskauer = positive

The identity of these organisms is most likely

peptidoglycan and teichoic acids

Which of the following cell wall components is associated with the ability of gram positive bacteria to retain the primary dye (crystal violet) during the Gram staining procedure

S. pneumonia

Which of the following must be placed in a CO₂ incubator or candle jar because it requires increased CO₂ for best growth (organisms exhibiting this behavior are referred to as being capnophilic)

Staphylococcus epidermidis

Gram positive cocci are the predominant organisms isolated from a decubitus ulcer (bed sore).  These gram positive cocci, which colonize moist areas of the skin, have the following biochemical characteristics:

catalase = positive coagulase = negative urease = positive

mannitol fermentation = negative arginine  dihydrolase = positive beta-galactosidase = negative

This organism is most likely

S. agalactiae (group B)

Which of the following is an important cause of neonatal sepsis (as a result of colonization of the vaginal tract of pregnant women)

Coagulase

By definition, all strains of Staphylococcus aureus produce an enzyme capable of clotting plasma.  This enzyme, which is called  ?  differentiates S. aureus from the other Staphylococcus species

Enterococcus faecalis

Numerous large, gray, non-hemolytic, translucent colonies are isolated from the blood agar plate of a urine culture.  Biochemical tests performed on these catalase negative, gram positive cocci give the following results:

Hippurate hydrolysis = positive Esculin hydrolysis = positive PYR hydrolysis = positive

Voges-Proskauer = positive Arginine dihydrolase = positive Ribose fermentation = positive

This organism is most likely

Streptococcus pneumonia

The gram stain of a rusty colored sputum sample revealed numerous gram positive cocci in pairs and numerous polymorphonuclear WBC's.  The gram positive cocci are encapsulated and lancet-shaped.  This organism is most likely

S. epidermidis

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

Staphylococcus aureus

Gram positive cocci are isolated from a wound culture exuding yellowish-colored pus.  These organisms have the following biochemical characteristics:

Catalase = positive Coagulase = positive Urease = positive

Mannitol fermentation = positive Arginine dihydrolase = negative Beta-galactosidase = negative

This organism is most likely

Shigella

Which one of the following genera is among the least biochemically reactive members of the Enterobacteriaceae

Beta-lactamase

Penicillin resistance in Neisseria gonorrhoeae can be due to the organism producing

Salmonella typhi

What is the etiologic (causative) agent of typhoid fever? Humans are the only reservoir

Moraxella catarrhalis

Moderate growth of oxidase positive, gram negative cocci are isolated from nasopharyngeal and throat cultures on a 7 y/o girl with otitis media (ear infection).  Biochemical tests produced the following results:

glucose utilization =  negative maltose utilization =  negative lactose utilization =  negative sucrose utilization =  negative

Growth on nutrient agar at 37° C no growth on Thayer-Martin agar nitrate reduction =  positive DNase production = positive

This organism is most likely

Ornithodoros species (soft bodied ticks)

The arthropod vector for endemic (or tickborne) relapsing fever is

Leptospira species

Which organism grows in a dense ring below the surface of Fletcher's media

Helicobacter pylori

The cause of gastritis and gastric ulcers

Neisseria meningitides

An 18-year-old boy is admitted to the hospital with suspected meningitis.  He is lethargic and presents with a rigid neck.  He has not had most of the recommended vaccines from childhood to now.  Gram stain of his spinal fluid shows many PMNs with intra and extra cellular Gram-negative diplococci.  The suspected pathogen is

N. gonorrhoeae

Purulent discharge from a newborn with conjunctivitis yields oxidase positive, gram negative diplococci from a subculture to a chocolate agar plate.  Biochemical tests provide the following results:

glucose utilization= positive maltose utilization= negative lactose utilization= negative sucrose utilization = negative

no growth on nutrient agar Growth on Thayer-Martin agar nitrate reduction = negative DNase production = negative

This organism is most likely

Legionnaires’ disease

A febrile and pneumonic illness first named in 1976 by scientists at the Centers for Disease Control and Prevention (CDC) who were investigating an epidemic of pneumonia among Pennsylvania State American Legion members attending a convention in Philadelphia is known as

Dogs   

The native hosts of Leptospira interrogans ss. canicola are

Borrelia burgdorferi

The appearance of the classic erythema migrans lesion is associated with which of the following

Ixodes species (hard bodied tick)

The vector for Lyme disease is

Chocolate and modified Thayer-Martin agars

A male urethral discharge specimen submitted for culture should be inoculated to

Escherichia coli

An organism gave the following reactions:
TSI:                               acid slant, acid butt, no H₂S, gas produced
Indole:                        positive
Motility:    positive
Citrate:                       negative
Lysine decarboxylase:     positive
Urea:                           negative
VP:                                negative
 
This organism most likely is

infectious jaundice

interrogans ss canicola is the causative agent of

Thiosulfate citrate bile salts (TCBS) agar

Vibrio parahaemolyticus is best isolated from feces on

Treponema carateum

The etiologic (causative) agent of pinta is

Borrelia recurrentis

Relapsing fever in humans is caused by

epidemic (louseborne) relapsing fever

Borrelia recurrentis, whose vector is the human body louse, is the causative agent of

H₂S production

Which feature distinguishes Erysipelothrix rhusiopathieae from other clinically significant non spore-forming, Gram-positive, facultatively anaerobic bacilli

Gardnerella vaginalis

A wet mount of vaginal fluid is examined microscopically and large squamous epithelial cells are seen with gram-variable bacilli clustered on the cell edges “clue cells”.  The pH of the fluid is 5.0.  The most likely pathogen is

Regan-Lowe agar

The best medium for culture of Bordetella pertussis is

demonstrate immunity to the diphtheria toxin

In the Schick test small amounts of toxin are injected under the skin to demonstrate the presence of neutralizing antibody (antitoxin).  The purpose if this test is to

Pseudomonas aeruginosa

An organism isolated from the surface of a skin burn is found to produce a diffusible green pigment (pyocyanin) on a blood agar plate.  Further studies of the organism would most likely show the organism to be

Bacillus anthracis

Purulent material is received from a finger lesion (a black, crusted, ulcerative lesion).  A Gram stain of purulent material revealed large, gram positive rods in chains.  After 18-24 hours of incubation in a CO2 incubator, examination of the blood agar plate reveals large, rough, non-hemolytic, colonies with swirling projections.  This organism is catalase positive, non-motile, and forms spores.  It is most likely

Nocardia

A braching Gram-positive, partially acid-fast organism is isolated from a bronchial washing on a 63-year-old woman receiving chemotherapy.  The organism does not hydrolyze casein, tyrosine, or xanthine.  The most likely genus causing the infection is

administration of tetanus antitoxin

A 23 year old victim of a motorcycle accident begins to experience muscle spasms in his right leg which had sustained a compound fracture.  The area around the traumatic wound is red and swollen.  Gram stain of the exudate reveals numerous pus cells, gram positive cocci, gram negative rods and large, gram positive bacilli. Aerobic cultures yield organisms normally found on the skin. An anaerobic organism is isolated on the anaerobic culture.  It is a gram positive rod with terminal spores.  Immediate treatment should include

M. leprae 

Which of the following species of Mycobacterium causes a chronic disease of the skin, mucous membranes, and nerve tissue but has not yet been cultivated in vitro

moderately obligate anaerobes

Most pathogenic anaerobic species isolated from clinical specimens are classified as

M. avium complex (MAC)

Due to decreased cellular immunity, AIDS patients in the U.S. are very susceptible to infections due to NTM (nontuberculous mycobacteria) bacilli, particularly

Mycoplasma pneumoniae

Which of the following requires sterols for growth? [A condition met by incorporating horse serum (cholesterol) into the growth medium.]

Erhlichia chaffeensis

Etiological agent for Human Monocytic Erhlichiosis (HME)

Listeria monocytogenes

Which of the following is a catalase positive, gram positive rod which is known to cause a mild, flu‑like illness in healthy adults but neonatal sepsis or meningitis in infants under one month of age?  This organism can be isolated from the gastrointestinal (GI) tract of many animal species and can be acquired by ingestion of foods associated with animal products (dairy foods for example) as well as contaminated fruits and vegetables

Mycoplasma pneumoniae

The major etiologic agent of primary atypical pneumonia is

growth rate and colonial pigmentation

The Runyon system of classification is based on

Growth at 42^o C

A characteristic that is helpful in separating Pseudomonas aeruginosa from other members of the Pseudomonas family is

Tinsdale 

On which of the following media does Corynebacterium diphtheriae produce black colonies with brown halos?  Diphtheroids may produce black colonies but they do not produce brown halos

HIV epidemic

The recent emergence of epidemic multidrug-resistant strains of M. tuberculosis, in conjunction with the end of the downward trend of reported cases of tuberculosis in the United States, has been largely attributed to

M. tuberculosis

A Mycobacterium species, with the following biochemical characteristics, is isolated from a sputum culture:

rate of growth = 14 to 28 days pigment in the dark = no pigment enhanced by light = no niacin test = positive nitrate reduction = positive

catalase reaction = negative tween 80 hydrolysis = negative arylsulfatase = negative urease production = positive tellurite reduction = negative

This organism is most likely

often carrying an antiphagocytic capsule

S. pneumoniae can be described as

glycoprotein

The chemical composition of bacterial capsules is most often

viridans streptococci

Small alpha hemolytic colonies are seen on the blood agar plate for a throat culture.  These organisms commonly colonize the upper respiratory tract.  Some species are associated with dental caries and can be a significant cause of subacute bacterial endocarditis following oral surgery.  These organisms are most likely

S. pneumonia

A physician suspects that a 5 y/o male patient is suffering from recurrent otitis media (inner ear infection).  He sends an ear swab to the lab for culture and susceptibility testing. After 18-24 hours alpha hemolytic, mucoid, convex colonies are seen on the blood agar plate.  After 48 hours the colonies are umbilicate (depressed centers).  The isolates are identified as catalase negative, gram positive cocci with the following biochemical characteristics:

hippurate hydrolysis = negative esculin hydrolysis = negative PYR hydrolysis = negative

optochin = positive (sensitive) arginine dihydrolase = positive trehalose fermentation = positive

The identity of these organisms is most likely

acute glomerulonephritis

Which of the following is a life-threatening, non-suppurative (no pus production) and non-invasive condition associated with S. pyogenes infection which can lead to kidney failure

Proteus vulgaris

The swarming gram-negative bacillus that can be presumptively identified on the basis of a positive indole test is

multiple resistance to antibiotics

The virulence of Serratia marcescens is associated with

Klebsiella pneumoniae

An organism isolated from a sputum specimen is seen as large, mucoid colonies on the blood and MacConkey agar plates.  On the MacConkey agar plate the colonies are pink to red indicating this organism is a lactose-fermenter.  This oxidase-negative, encapsulated, gram negative rod is most likely

Weil's disease

Leptospira interrogans ss.
icterohaemorrhagiae is the etiological agent of

Syphilis

Granulomatous lesions called gumma (which affect the skin, mucous membranes, soft tissue, bone, CNS, and the cardiovascular system) are seen in the tertiary stage of   ?  , a sexually transmitted disease

Thiosulfate citrate bile salts sucrose for Vibrio species (TCBS)

A community hospital microbiology laboratory is processing significant numbers of stool cultures because of an outbreak of diarrhea following heavy rains and flooding in the county. A media that should be incorporated in the plating protocol is

E. coli O157:H7 (STEC)

Which of the following is the causative agent of hemolytic uremic syndrome (HUS) and hemorrhagic colitis

Escherichia coli

A gram negative rod which normally resides in the colon is a major cause of nosocomial urinary tract infections.  It is oxidase negative, but indole, lysine, ornithine, and motility positive.  It characteristically forms beta hemolytic colonies on sheep blood agar and is also a lactose fermenter.  What is the name of this organism

Legionella pneumophila

The causative agent of pneumonic legionellosis (Legionnaire’s disease) is

Campylobacter jejuni

The leading cause of bacterial diarrhea worldwide

Borrelia burgdorferi

The most common vector-borne disease in North America and Europe transmitted by the bite of Ixodes ticks is caused by

Bacillus anthracis

Fluid from a cutaneous black lesion was submitted for routine bacterial culture.  After 18 hours of incubation at 35^oC there was no growth on MacConkey agar, but 3+ growth on sheep blood agar.  The colonies were nonhemolytic, nonmotile, 4-5 mm in diameter and off-white with a ground glass appearance.  Each colony has an irregular edge with comma-shaped outgrowths that stood up like “beaten egg whites” when gently lifted with an inoculating needle.  A Gram stain of typical colony showed large, Gram-positive rectangular bacilli.  The organism is most likely

The medium contains whole eggs, salts, potato flour, and malachite green (to inhibit contaminants)

Choose the statement which is CORRECT
concerning Lowenstein-Jensen slants which are used to isolate Mycobacterium
species

The beta-lactamase enzyme

Haemophilus influenzae becomes resistant to ampicillin when the organism produces

Coxiella burnetii

Etiological agent of Q fever

Bacteroides fraglis

The presence of 20% bile in agar will allow growth of

Prevotella melaninogenica

An anaerobic, gram negative coccobacillus is isolated from a pelvic abscess.  The organism possesses the following biochemical characteristics:

Catalase = negative Indole = negative Esculin hydrolysis = negative

Lipase = negative Black pigment on anaerobic blood agar Major acids = succinic and acetic

This organism is most likely

media with cysteine such as buffered charcoal yeast extract agar

Appropriate culture requirements for a specimen from a patient suspected of having tularemia include

8 weeks

Because acid fast bacilli are slow growing organisms, cultures for Mycobacterium species should be held for  ?  before reporting out as negative (no growth)

Klebsiella granulomatis

?  is the cause of granuloma inguinale.  This organism can not be cultivated on routine laboratory media.  Diagnosis is based on symptomology and observing Donovan bodies within large mononuclear cells.  The Giemsa stain is used to stain smears of tissue from granulomatous lesions in the genital region

Pseudomonas aeruginosa

The predominant organism growing on a sputum culture is a beta hemolytic, oxidase positive, long, thin, gram negative rod which produces flat, spreading colonies.  These organisms exhibited the following biochemical characteristics:

glucose oxidation = positive xylose oxidation = positive maltose oxidation = negative

Fluorescein = positive Pyocyanin production = positive arginine dihydrolase = positive

In addition, this organism produced a greenish pigment.  This organism is most likely

C. perfringens

Which Clostridium species is most often recovered from a wound infection with gas gangrene

Hemin synthesis

The porphyrin test was devised to detect strains of Haemophilus capable of

Mycoplasma hominis

Which of the following is associated with nongonococcal urethritis and pelvic inflammatory disease?  Colonies on agar based media are said to have a “fried egg” appearance and range in size from 50-500μm in size

Streptococcus pyogenes (gp A)

Small beta hemolytic colonies are seen on the blood agar plate for a throat culture (performed to identify the cause of pharyngitis).  They are transparent with large zones of beta hemolysis.  They are susceptible to bacitracin (positive) and PYR hydrolysis positive.  These colonies are most likely

phenylethanol agar                                                

Which of the following media is selective for gram positive bacteria (inhibits the growth of gram negative bacteria)?  This medium is used to isolate gram positive cocci such as staphylococci and streptococci from specimens taken from areas colonized by other microbes

lipopolysaccharides

Which of the following cell wall components contains the toxic component of gram negative cell walls (lipid A)

Campylobacter fetus

Isolated from the blood of immunosuppressed patients

Aeromonas hydrophila

An oxidase positive,  gram negative rod isolated from a stool culture has the following biochemical characteristics:

lactose fermentation = negative sucrose fermentation = positive DNase production = positive gelatin hydrolysis = positive

no growth in 3% NaCl ornithine decarboxylase = positive lysine decarboxylase = negative arginine dihydrolase = positive

This organism is most likely

N. meningitidis

Oxidase positive, gram negative diplococci (g-dc) are isolated from a blood culture on a nine month old infant.   Suspected diagnosis: septicemia.  The following biochemical characteristics are found:

glucose utilization = positive maltose utilization = positive lactose utilization = negative sucrose utilization = negative

no growth on nutrient agar growth on Thayer-Martin agar nitrate reduction = negative DNase production = negative

This organism is most likely

Cholera toxin (CT)

Profuse watery diarrhea (i.e., “rice water stools”), leading to dramatic fluid loss, severe dehydration, and hypotension that frequently leads to death, is the hallmark of which toxin activity

Yersinia pestis

A 32 year old male from Arizona has a fever of unknown origin.  Lymph nodes in his groin were swollen (buboes).  The patient had been hunting and came across a dead ground squirrel which he moved aside with his foot.  A lymph node aspirate is gram stained revealing gram negative rods exhibiting bipolar staining ("closed safety pins").  This organism, transmitted by flea bites, is known as

Culture on buffered charcoal yeast extract agar with antibiotics (BCYE)

A bronchoscopy sample with the request for culture of Legionella is sent to the laboratory.  The correct plating protocol is

was all of these

E. coli is capable of causing

Escherichia coli

Infection of the urinary tract is most frequently associated with

demonstrate exposure to Mycobacterium species and seroconversion

The PPD (purified protein derivative) or Mantoux skin test is used to

Haemophilus influenzae       

An ear swab from a 5 y/o with recurrent ear infections is sent to the lab.  The isolate grows luxuriantly on the chocolate agar plate (producing a “mousy” odor).  It appears as small colonies satelliting the Staphylococcus epidermidis colonies growing on the blood agar plate.  A gram stain reveals the organisms are pleomorphic, gram negative coccobacilli.  A porphyrin test reveals the organism is X-dependent (cannot synthesis hemin from delta aminolevulinic acid.  This organism is most likely

Clostridium tetani

A strict anaerobe that produces terminal spores “tennis racquet” is

Haemophilus influenza

An organism that exhibits the satellite phenomenon around colonies of Staphylococcus aureus is

An exotoxin producer

The etiologic agent of botulism is

Pseudomonas aeruginosa

What oxidase positive, non-fermenting, gram negative rod is a particular problem for cystic fibrosis patients?  Most isolates are encapsulated and form mucoid colonies

Middlebrook 7H10 and 7H11

Which of the following is a clear, chemically defined, agar-based medium used to isolate acid fast bacilli

C. difficile

Which Clostridium spp. Causes pseudomembranous colitis or antibiotic-associated colitis

plasmid

Extrachromosal DNA which is capable of transferring antibiotic resistance is known as a

Contact with cold-blooded animals such as reptiles and fish

The source of human infection (gastroenteritis) caused by Edwardsiella tarda is