Mycoplasma hominis, Molecular Detection, PCR
Rapid, sensitive, and specific identification of Mycoplasma hominis from synovial fluid, genitourinary, reproductive, lower respiratory sources, pleural/chest fluid, pericardial fluid, and wound specimens
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Mycoplasma hominis has been associated with a number of clinically significant infections, although it is also part of the normal genital flora.
M hominis may be found in the respiratory specimens and spinal fluid of neonates. Although the clinical significance of such findings is often unclear, as spontaneous clinical recovery may occur without specific treatment, in premature infants, clinical manifestations of meningoencephalitis have been reported.
M hominis may play a role in some cases of pelvic inflammatory disease, usually in combination with other organisms. M hominis may be isolated from amniotic fluid of women with preterm labor, premature rupture of membranes, spontaneous term labor, or chorioamnionitis; there is evidence that it may be involved in postpartum fever or fever following abortion, usually as a complication of endometritis.
M hominis has rarely been associated with septic arthritis (including prosthetic joint infection), pyelonephritis, intraabdominal infection, wound infection, endocarditis, central nervous system infection (including meningoencephalitis, brain abscess, central nervous system shunt infection and subdural empyema), pneumonia, and infected pleural and pericardial effusions. Extragenital infection typically occurs in those with hypogammaglobulinemia or depressed cell-mediated immunity; in lung transplant recipients in particular, M hominis has been associated with pleuritis and mediastinitis. Recent evidence implicates donor transmission in some cases of Mycoplasma hominis infection in lung transplant recipients.
PCR detection of M hominis is sensitive, specific, and provides same-day results. Although this organism can occasionally be detected in routine plate cultures, this is neither a rapid nor a sensitive approach to detection. Specialized cultures are more time consuming than the described PCR assay. The described PCR assay has replaced conventional culture for M hominis at Mayo Medical Laboratories due to its speed and equivalent performance to culture.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
A positive PCR result for the presence of a specific sequence found within the Mycoplasma hominis tuf gene indicates the presence of M hominis DNA in the specimen.
A negative PCR result indicates the absence of detectable M hominis DNA in the specimen, but does not rule-out infection as falsely negative results may occur due to inhibition of PCR, sequence variability underlying the primers and probes, or the presence of M hominis in quantities less than the limit of detection of the assay.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Interfering substances may affect the accuracy of this assay; results should always be interpreted in conjunction with clinical and epidemiological findings
Since Mycoplasma hominis may be part of the normal flora, results should be interpreted accordingly.
This test does not detect other mycoplasmas or ureaplasmas (including Mycoplasma pneumoniae, a common cause of community acquired pneumonia).
This assay was clinically validated in a blinded manner using 292 archived specimens submitted for Mycoplasma hominis culture, 281 of which were in M4, M5, or Universal Transport Media (UTM). The specimens consisted of 251 genitourinary, 32 reproductive fluids or tissues, and 9 respiratory specimens. Compared to culture, PCR had 90.7% (39/43) sensitivity and 99.2% (245/247) specificity (p=0.41). Discordant results on the archived specimens (n=6) were tested by PCR by Dr. Kathleen A Stellrecht at the Albany Medical Center.(1) Dr. Stellrecht found both of the PCR-positive/culture-negative specimens to be PCR positive, and 3 of 4 specimens that were PCR negative/culture positive to be PCR negative. The limit of detection of the assay is 100 targets/mcL for all validated sources. Out of 178 bronchoalveolar lavage fluid specimens from immunocompromised hosts tested using the assay, none were positive.