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list reasons for performing molecular microbiology testing in place of traditional microbiology cultures.

1. Microorganisms not easily cultured (legionella)
2. Slow growing microorganisms (M. tuberculosis)
3. low volume tests added little to the lab budget or workload
4. tests that make money and save money? (outpatient)
5. high/low volume tests


List mycobacterial species identified by DNA probe technology- Gen-probe Accuprobes.

Mycobacterium tuberculosis complex (tuberculosis, bovis, africanum);
mycobacterium avium complex (avium and intracellulare);
mycobacterium gordonae and kanasaii.


List the mycobacterial species identified by DNA probe technology- Cepheid (GenExpert)

M. tuberculosis and Rifampin susceptibility


Indicate the color of fluorescence of the Candida species - albicans, tropicalis, glabrata when detected by PNA-FISH

C. albicans - green
C. trophicalis- Yellow
C. glabrata/krusei- red


For the BD GeneOhm MRSA assay, indicate which part of the staphylococcal chromosome must be detected to definitely identify MRSA.

DNA detection of the SCCmec-orfX junction found only in MRSA provides definitive identification of MRSA.


This method requires isolated colonies or high bacterial concentrations, and does identification only. Instrument is expensive and reagents can be cheap.



This method does direct Identification from patient specimens and detection of resistance genes. cheap instrument/expensive reagents.

Molecular methods


explain why enrichment broth is required for optimal screening for maternal colonization by streptococcus agalactiae.

Allows organism to grow overnight with enough copies of the organism


List sexually transmitted diseases commonly detected by molecular methods.

GC, CT, TV, and HPV


explain how HIV-1 viral load predicts clinical course in HIV/AIDS

the viral load levels as low as possible for as long as possible decreases the complications of HIV disease, slows the progression from HIV infection to AIDS, and prolongs life. So, increase in viral load in HIV-1 leads to AIDS. CD4 <200 = AIDS + HIV


Discuss the importance of HIV-1 genotyping in patient management.

Examine the HIV genome for resistance associated mutations in the PR and RT regions; because the virus multiplies too fast


Enzyme used in Transcription mediated amplification (TMA)

RT and RNA polymerase.


Temperature of reaction in TMA

Isothermal reaction (no thermocycler), room temperature


Indicate which analytes are most commonly detected by the TMA method in the U.S.

Neisseria gonorrhoeae and Chlamydia trachomatis (also detects TV and HPV high risk)


List the types of clinical specimens useful for molecular detection of GC, CT, TV and HPV.

Urine, urethral/cervical swab, and Pap smear sample


List several different methods for identifying bacteria and yeast directly in blood cultures.

AccuProbe, PNA FISH< QuickFISH, real time PCR (cepheid and BD), and Multiplex PCR (biofire, Verigene)