lOWER rESPIRATORY
When performing quantitative cultures from protected brush specimens, which of the following colony forming units per milliliter indicates a true bacterial pneumonia?
>103 colony forming units/mL
When performing quantitative cultures from bronchoalveolar lavage specimens, which of the following colony forming units per milliliter indicates a true bacterial pneumonia?
>104 colony forming units/mL
The upper photomicrograph illustrates a Gram stain of sputum obtained from a 55-year-old man with symptoms of bacterial pneumonia. The lower photograph represents the growth of an inoculum from the specimen on 5% sheep blood agar, on which had been placed an optochin ("P") and a 1 µg oxacillin disk. After 18 hours incubation at 37°C in 5% CO2, the zone around the optochin disk is 18 mm and around the OX disk is 8 mm. The interpretation is that the organism is most likely:
A pneumococcus, penicillin resistant
The bacterial species growing on the surface of the MacConkey agar plate shown in this photograph, a coccobacillary non-fermenter and a common cause of nosocomial hospital-acquired pneumonia, can be presumptively identified as:
Acinetobacter baumannii
The organism Acinetobacter baumannii is known to have caused which of the following outbreaks?
Afghanistan and Iraq U.S. soldiers outbreak*
A 70-year-old man who three days previously had incurred a cerebral vascular accident was semi-comatose and having difficulty breathing. He developed sudden fever overnight and was found to have pneumonia. The Gram stain shown in this photomicrograph was obtained from purulent material obtained through the intubation tube.What is the most likely type of pneumonia?
Aspiration pneumonia*
Which of the following is the primary virulence factor in Streptococcus pneumoniae?
Capsular polysaccharide
The following is the primary virulence factor produced by Streptococcus pneumoniae that prevents phagocytosis:
Capsule
A physician called the microbiology laboratory and asked what he needed to order to diagnose Bordetella pertussis from a child who had what appeared to be having whooping cough. Which of the following should the physician be told to order?
Both direct fluorescent antibody (DFA) test and culture
The best clinical specimen for the recovery of Legionella pneumophilia is:
Bronchial washings
A patient with cystic fibrosis is admitted with a fulminant lung infection. A sputum culture grows a non-lactose fermenting, oxidase positive, Gram-negative bacilli. It is pyocyanin negative, nitrate reduction variable, and it is arginine dihydrolase negative.
Burkholderia cepacia
Bacteria may be the agents of infections in plants as well as in animals. This organism is the agent of onion bulb rot in plants, but is also an important agent of hospital-acquired infections in humans.
Burkholderia cepacia
The following is a non-fermenting, oxidase positive, motile, opportunistic pathogen that most commonly causes respiratory infections associated with chronic granulomatous disease and cystic fibrosis. On sheep blood agar, the organism is described as being small, entire, gray-yellow colonies. On MacConkey, it may appear light pink as shown in the photograph. Identification tests that assist in the identification include Alk/Non-reactive on TSI, lysine decarboxylase positive, oxidation of glucose, lactose, and xylose. It also does not produce gas from nitrate reduction. Which of the following organisms matches the description?
Burkholderia cepacia*
What organism produced outside a bioterrorism event causes glanders disease?
Burkholderia mallei
Direct detection methods are available for Bordetella pertussis from nasopharyngeal specimens; however, caution should be used when collecting the specimen because inhibition can occur based on the type of swab that is used. Which of the following swabs have an inhibitory effect on PCR testing for Bordetella pertussis?
Calcium-alginate swabs on wire shaft
Which of the following organisms causes Q fever?
Coxiella burnetii
The small beta hemolytic bacterial colonies growing on blood agar as shown in the upper photograph were recovered from an induced sputum specimen from a young child with pneumonia. The colonies were slow growing, small, entire and show soft beta hemolysis. Plump, Gram-negative coccobacilli, lying singly, in pairs and short chains, are seen on gram stain as illustrated in the lower photomicrograph. Most strains are chemically non-reactive except for a positive oxidase reaction and acid produced from dextrose and maltose. What is the name of the isolate?
Kingella kingae
A sputum specimen submitted for culture is brick red in color. The organism causing this sputum color, also has a distinct polysaccharide capsule and is non motile. What organism can be associated with this sputum?
Klebsiella
A 42-year-old chain smoker experienced an increase in cough, sputum production, and intermittent shortness of breath for over one week. A diagnosis of chronic bronchitis with acute exacerbation was made. The image shows a Gram stain of an early morning, spontaneously expectorated sputum. Based on the pleomorphic coccobacilli shown in the Gram stain, what is the most likely cause of the exacerbation?
Haemophilus influenzae
Which of the following anthrax infections is also known as "woolsorter's disease"?
Inhalation anthrax
All of the following statements about Coxiella burnetii are true, EXCEPT:
It is best diagnosed by culture of the organism
A culture from a sputum specimen grew a mucoid, lactose fermenting organism. Biochemical testing on this isolate gave the following key reactions: VP: positive; Indole: negative; Urea: 1+, Motility: nonmotile, Citrate: positive. What is the most likely organism given the site of isolation and biochemical reactions?
Klebsiella pneumoniae
The distinctly large, spreading, mucoid colonies seen on blood agar in the upper left image, and the display of lactose fermentation on MacConkey agar in the upper right image provide for a presumptive organism identification. This species is most commonly recovered from respiratory specimens of patients with pneumonia. Observing absence of motility, a weak reaction for urea, and strong reactions for citrate and Voges-Proskauer confirm the presumptive identification. From the multiple choices, select the name of the isolate presented here.
Klebsiella pneumoniae
The Gram stain of a sputum is unremarkable but the culture reveals many small gram-negative rods that are able to grow only on charcoal yeast extract agar. What is the MOST likely diagnosis?
Legionnaire's disease
Performing quantitative cultures on bronchoalveolar lavage and protected brush specimens are better than performing routine semi-quantitative cultures because in quantitative cultures there should be which of the following?
Low numbers of contaminating normal respiratory flora and colonizing organisms and higher numbers of potential pathogens.
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)
Two sputum specimens were submitted to the Microbiology laboratory for culture. A Gram stained smear was evaluated for each specimen prior to culturing. The fields that are shown in these images are representative of the 20 - 30 low power fields (lpf) that were examined. Which one of the two results represents a sputum specimen that is acceptable for culturing?
gRAM STAIN a
A gram negative, oxidase-positive diplococcus was the predominant isolate from a sputum specimen of a patient with chronic obstructive pulmonary disease (COPD). Based on the reactions seen in the Quad-FERM system shown in the photograph, the most likely identification is:
Moraxella catarrhalis
The purulent exudate and the intracellular bacteria (shown by the arrows) as illustrated in this photograph to the right was observed in a direct sputum gram stain of a 70 year-old patient with chronic obstructive pulmonary disease. Which bacterial species most likely grew out in culture?
Moraxella catarrhalis
Which organism is a cell wall deficient bacterium that commonly causes primary atypical or "walking pneumonia?
Mycoplasma pneumoniae
The colonies observed in the upper image on the right are non-pigmented and dry to chalky. They were recovered from an expectorated sputum sample of an immunocompromised 70-year-old man with pneumonia. The Gram stain shown in the lower image to the right depicts delicate, branching bacilli. Based on this information, what is the most likely identification of this pathogen?
Nocardia asteroides
The antiphagocytic capsule of Streptococcus pneumoniae is composed of:
Polysaccharides
What virulence factor is not inherent to bacterium?
Production of opsonins
What bacterial species is rarely part of normal microbiota of healthy humans?
Pseudomonas aeruginosa
Which Pseudomonas species produces pyocyanin (bright bluish pigment on Mueller-Hinton agar)?
Pseudomonas aeruginosa
The granular, wrinkled, yellow-pigmented colonies shown in the upper photograph were recovered on chocolate agar after 48 hours of incubation from a respiratory specimen collected from a patient with cystic fibrosis. Note in the lower composite photograph that colonies on the surface of blood agar are flat, granular, and only slightly wrinkled. On MacConkey agar the colonies lack lactose fermentation and lack pyocyanin production. The spot oxidase test is positive, and nitrates are reduced. With these observations, select the presumptive identification of this isolate.
Pseudomonas stutzeri
A protected brush specimen was received into the microbiology laboratory from an ICU patient and cultured using a 0.001-mL loop. The culture grew 3 colonies of Pseudomonas aeruginosa. Which of the following is the correct way to report out the organism?
Report out 3,000 CFU/mL of Pseudomonas aeruginosa
On a plate growing Streptococcus pneumoniae, the zone of inhibition around the disk shown in the image has been measured at 23 mm. Based on this result, you should:
Report oxacillin-susceptible
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.
A suspected nocardioform bacterial species was recovered from sputum. The isolate produced mucoid colonies with pink pigment after 4 days on SBA, as shown in the associated image. Staining demonstrated diphtheroid, Gram positive rods with a few branching filaments. It also stained partially acid fast. The most likely identification is:
Rhodococcus equi
All of the following organisms have capsular material as a defense mechanism EXCEPT:
Staphylococcus saprophyticus
A 67-year-old man was seen in the emergency room complaining of cough, fever, and piercing right posterior chest pain. X-ray of the chest revealed consolidation of the right middle lobe of the lung. A sputum culture grew the bacterial species shown in the upper photograph. The lower photomicrograph illustrates a gram-stain of the sputum specimen. The most likely cause of the pneumonia is:
Streptococcus pneumoniae
A catalase-negative, a-hemolytic, gram-positive diplococci was isolated from a sputum specimen. The image shown here demonstrates a zone of growth inhibition around the "P disk," indicating optochin susceptibility. What is the identification of this isolate?
Streptococcus pneumoniae
A patient was admitted to the hospital recently with an obvious infection. A sputum specimen was submitted and the microbiologist inoculated it to sheep's blood agar. Based on the colony morphology and the alpha hemolysis seen in the image to the right, the most likely identification is:
Streptococcus pneumoniae
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 microscopic image shown here is a direct Gram stain of sputum obtained from a 70-year-old man complaining of cough, sputum production, and chest pain. This organism was alpha-hemolytic on blood agar, catalase negative, optochin ("P disk") susceptible, and bile soluble. What is the identity of this organism?
Streptococcus pneumoniae
The microscopic view of a Gram stained sputum specimen reveals lancet-shaped, Gram positive diplococci. What presumptive identification may be made?
Streptococcus pneumoniae
The optochin (ethylhydrocupreine hydrochloride) disk is most often used for the identification of which organism?
Streptococcus pneumoniae
The organism in the attached photos was isolated from a sputum specimen. The blood agar plates were incubated at 37° C. The upper photo shows 24 hour incubation and the lower photo shows 48 hour incubation. The Gram stain showed lancet-shaped Gram positive cocci in pairs. What is the most likely identification of this organism?
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
All of the organisms listed below are matched with the most likely clinical condition found in patients with that organism, EXCEPT:
Streptococcus pneumoniae - cellulitis
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.
