From the Guidelines
To check for a current cytomegalovirus (CMV) infection, the most appropriate laboratory test is CMV PCR (polymerase chain reaction) due to its high sensitivity and ability to detect viral DNA in various samples. This is supported by the study 1, which highlights the advantages of PCR, including rapid results, high sensitivity, and the potential for qualitative and quantitative testing. The study also notes that PCR can detect CMV DNA in a wide range of samples, making it a versatile and effective diagnostic tool.
When considering the diagnosis of CMV infection, it's essential to note that serology has limited value due to the high seroprevalence of CMV in the adult population 1. However, detection of CMV-specific antibodies, such as CMV IgM and IgG, can be useful in diagnosing recent infection or past exposure. CMV IgM antibodies suggest recent infection, while IgG indicates past exposure 1.
In addition to PCR, CMV antigenemia assay can also be used to detect active viral replication 1. This assay detects CMV pp65 antigen in white blood cells and can be useful in monitoring infection and antiviral treatment in immunocompromised patients. However, it's essential to note that antigenemia assays are only semiquantitative and may not provide a complete picture of the infection.
Other diagnostic methods, such as conventional viral culture and shell vial culture, are available but have limitations, including long incubation times and lower sensitivity compared to PCR and antigenemia assays 1. Histopathology combined with immunohistochemistry can also be used to verify CMV infection in tissue or biopsies, but this method may not be as readily available or practical for routine diagnosis.
In summary, CMV PCR is the most appropriate laboratory test for diagnosing current CMV infection, due to its high sensitivity, rapid results, and versatility in detecting viral DNA in various samples 1. This test should be combined with CMV IgM and IgG antibody testing to provide a comprehensive assessment of the infection. In immunocompromised patients, viral load monitoring through quantitative PCR is essential to guide treatment decisions 1.
From the Research
Lab Tests for Current CMV Infection
To check for a current CMV infection, several lab tests can be utilized, including:
- Culture: This involves taking a sample from the patient, such as urine, blood, or genital secretions, and attempting to grow the virus in a laboratory setting 2.
- Cytology: This involves examining cells from the patient for signs of CMV infection, such as the presence of CMV inclusions 2.
- Serology: This involves measuring the levels of CMV-specific antibodies, such as IgG and IgM, in the patient's blood 2, 3, 4.
- Detection of CMV antigens and/or nucleic acids: This involves using techniques such as PCR to detect the presence of CMV DNA or antigens in the patient's samples, such as blood, urine, or cerebrospinal fluid 2, 4.
Sample Types for CMV-DNA Detection
The detection of CMV-DNA can be performed on various sample types, including:
- Blood: This is a common sample type used for CMV-DNA detection, and the positive rate of CMV-DNA in blood samples has been reported to be around 26.01% 4.
- Urine: This is another common sample type used for CMV-DNA detection, and the positive rate of CMV-DNA in urine samples has been reported to be around 25.27% 4.
- Cerebrospinal fluid (CSF): This sample type is less commonly used for CMV-DNA detection, but can be useful in certain cases, such as when CMV infection of the central nervous system is suspected 4.
Diagnostic Values of CMV-DNA Detection
The detection of CMV-DNA has been shown to be a valuable tool for diagnosing CMV infection, particularly in immunocompromised patients such as those with HIV/AIDS 4. The use of real-time fluorescence quantitative PCR for detecting CMV-DNA in urine or plasma samples has been reported to be highly valuable in screening for CMV infection in HIV/AIDS patients 4. However, the detection of blood CMV IgG and CMV IgM levels has been reported to have limited clinical value 4.