Review Note

NON-culture-based detection: molecule diagnostic techniques

- {{c1::Nucleic acid amplification tests (NAATs)}} detect bacterial nucleic acid from either direct specimen or cultured bacterial isolates
→ provided increased {{c2::sensitivity}} of detection and decreased {{c3::time}} to detection for many bacterial pathogens

- can be highly {{c4::complex}} tests that require specialized staff or "on demand" assays that can be easily conducted

- can be particularly useful for detection and identification of {{c5::fastidious}} organisms (those that have {{c6::specialized}} growth conditions or are {{c7::slow}} or noncultivable under laboratory conditions)

- numerous molecular tests are available to identify poorly cultivable or atypical organisms:

→ Bordetella pertussis
*successful isolation of organism declines significantly beyond first 2 weeks of illness and with prior antibiotic therapy
*B. pertussis is {{c9::fastidious}} and requires 3 to 6 days of incubation to form detectable colonies by culture and often will not grow if cultures are not initiated within 48 hours of sample collection
*PCR detection of B. pertussis DNA has become increasingly available for the timely diagnosis of pertussis

→ Bartonella henselae

→ Mycoplasma pneumoniae

→ Mycobacterium tuberculosis
*poor sensitivity of standard laboratory tests for the detection of M. tuberculosis is a major obstacle → tests based on nucleic acid amplification have offered rapid turnaround time of hours or days in contrast to {{c8::weeks}} required with culture

→ Chlamydia trachomatis
→ Neisseria gonorrhoeae
*^^for both, nucleic acid amplification testing of {{c10::urine}} specimens offers {{c11::noninvasive}} sample collection, provides ability to test for both GC and CT in same specimen, and facilitates sensitive and specific screening with a limit of detection as low as a single {{c12::gene}} copy