HARR-Aerobic Gram-Positive Rods, Spirochetes, Mycoplasmas and Ureaplasmas, and Chlamydiae

Flashcards covering aerobic gram-positive rods, spirochetes, mycoplasmas, ureaplasmas, and chlamydiae.

Bacillus spp.

Large, gram-positive, spore-forming rods growing on blood agar as large, raised, β- hemolytic colonies that spread and appear as frosted green-gray glass.

Motility and β-hemolysis

The best tests to differentiate Bacillus anthracis and Bacillus cereus on a blood agar plate.

B. cereus

β-hemolytic and motile, but B. anthracis is neither.

Suspected food

The specimen of choice for proof of food poisoning by B. cereus.

Penicillin (10-unit) susceptibility test

The test that should be performed next on a suspected B. anthracis culture obtained from a wound specimen that produced colonies that had many outgrowths (Medusa-head appearance) but were not β-hemolytic on sheep blood agar.

Gram stain, motility at room temperature, catalase

The tests that should be performed for initial differentiation of L. monocytogenes from group B streptococci.

Erysipelothrix rhusiopathiae

Catalase negative, produces H2S, non-motile at room temperature, and shows bottle-brush growth in gel media at 22°C, and is obtained from a finger wound specimen from a meat packer.

Lactobacillus spp.

Nonspore-forming, slender, gram-positive rods forming palisades and chains recovered from a vaginal culture and grows well on tomato juice agar.

Exotoxin, pseudomembrane of the oropharynx, Gray-black colonies with a brown halo on Tinsdale agar

Conditions where Corynebacterium species recovered from a throat culture are considered a pathogen.

Oxidase and catalase tests, Pleomorphic bacilli heavily colonized on vaginal epithelium, Hippurate hydrolysis test

Findings that can be used to make a presumptive diagnosis of Gardnerella vaginalis.

Nocardia spp.

A gram-positive branching filamentous organism recovered from a sputum specimen that was found to be positive with a modified acid-fast stain method.

Serological analysis

Routine laboratory testing for Treponema pallidum.

Borrelia spp.

Spirochetes often detected in the hematology laboratory while scanning a blood film, even before the physician suspects the infection.

Borrelia burgdorferi

The cause of Lyme disease.

Serology

The diagnostic method most commonly used for the identification of Lyme disease.

Mycoplasma pneumoniae

The cause of primary atypical pneumonia.

Mycoplasma hominis

Organism that typically produces “fried egg” colonies on agar within 1 to 5 days of culture obtained from a genital specimen.

Ureaplasma urealyticum

The organism for which the manganous chloride–urea test is used for identification.

Nocardia spp.

A gram-positive (gram-variable), beaded organism with delicate branching recovered from the sputum of a 20-year-old patient with leukemia that produced orange, glabrous, waxy colonies on Middlebrook agar that showed partial acid-fast staining with the modified Kinyoun stain.

Corynebacterium spp.

A direct smear from a nasopharyngeal swab stained with Loeffler methylene blue stain showed various letter shapes and deep blue, metachromatic granules.

10% KOH test

The best, rapid, nonculture test to perform when G. vaginalis is suspected in a patient with vaginosis.

PCR molecular testing

The test of choice for the confirmation of Chlamydia trachomatis infection in urine.

EIA testing and direct antigen testing

The most reliable test for the detection of M. pneumonia in serum and for the confirmation of diagnosis.

Chlamydia (Chlamydophila) psittaci–fecal swab

The bacterium–specimen pairing that is mismatched (specimen not appropriate for isolation).

Ehrlichia and Anaplasma spp.

The organisms are transmitted to animals and humans after a tick bite.

Blood, CSF, skin biopsy

The specimen(s) should be obtained to establish a diagnosis of Lyme borreliosis after a young male noted a tick on his ankle and subsequently noticed a circular, “bull’s eye” rash at the site of the bite.

Rhodococcus equi

The most likely presumptive identification of partially acid-fast, gram-positive, filamentous-branching bacteria that fragmented into rods and cocci seen in a sputum sample from a patient with HIV infection.

Culture

The category of testing that should not be utilized to establish a final identification of Mycoplasma genitalium in an asymptomatic 25-year-old female patient with persistent nongonococcal urethritis (NGC) and pelvic inflammatory disease (PID).