Diagnosis of infectious diseases

What are smears and bacterial inoculations? What is PCR-diagnosis? Why do we need enzyme immunodetection?
Methods for infectious diseases diagnosis can be divided into two groups: identification of pathogens (bacteria and viruses) and identification of antibodies to them.

Moreover, each method has a unique approach to various infections. Accuracy of diagnosis and correctness of a chosen method depend on a doctor's skills. Each new result of a laboratory study opens the next layer in the disease pattern, allowing choosing individual and optimal treatment.

What are smears and bacterial inoculations?

Smear is the most common method of laboratory diagnosis. Analysis is performed using a light microscope, so it is the oldest one in medicine. Gynecological analysis of scraping from urethra or vagina helps determining: the number of white blood cells (their increase speaks of infection, however, healthy women have a small number of leukocytes present in flora), the number of red blood cells (the main indicator of inflammation with increased number); flora composition (it depends on menstrual cycle, but cells activity indicates microflora disease), presence of Trichomonas, gonococci, fungus - the main objective to identify infectious agents; presence of lactobacilli (their absence speaks of broken microflora). Smear also determines the degree of vagina purity: 1 and 2 degree - typical for a healthy flora, and 3 and 4 - identify coleitis inflammation. Before any smear, it is better to refrain from urinating; otherwise the analysis pattern will not be clear.

Bacterial inoculation is a method of microbes’ cultivation on the basis of scraping, placed in a positive environment. It is the gold standard in infection determining, since detects not only a virus, but also its activity.

Bacterial inoculation allows receiving antibiogram helping the doctor prescribing an exact treatment. Bacterial inoculation is most frequently used to diagnose ureaplasmosis, mycoplasmosis, trichomoniasis, chlamydia, various forms of candidiasis.

Terms of bacterial inoculation analysis: do not squirt one day before, do not use vaginal suppositories, abstain from sexual intercourse a day before the analysis; stop taking antibiotics a week before, do not empty the bladder 1,5-2 hours before.

What is PCR-diagnosis?

PCR diagnosis or polymerase chain reaction, aimed at identifying specific nucleotide sequence of DNA site of an infectious agent. That is, inside the cell; and this cannot be achieved through a smear or bacterial inoculation.

PCR diagnosis indicates presence of virus in scraping of vagina, urethra, or urine most accurately.

DNA analysis is often used to identify: chlamydia, ureaplasmosis, mycoplasmosis, genital herpes, gonorrhea, trichomoniasis.

PCR diagnosis is indispensable for identification of viral hepatitis and HIV infection.

Even if infection is latent and sluggish, this method can identify the pathogen even at the stage of incubation period. However, it does not show viral activity.

Rules of PCR diagnostics are the same as when bacterial inoculation.

Why do we need enzyme immunodetection?

In contrast to smears, bacterial inoculation and PCR, enzyme immunodetection deals with blood, which contains antigens to alien organisms, such as viruses and bacteria.

Antigen - a protein-immunoglobulin derived from the body strictly for a certain microorganism. Presence of antigen indicates the type of pathogen, and the number - stage of infection development.

The system antigen-antibody is introduced an enzyme, which binds with certain substances and dyes. Study of color allows drawing conclusions.

EIA allows diagnosing: viral infections - hepatitis, HIV, herpes virus, rubella, cytomegalovirus, bacterial infections - tuberculosis, Lyme disease, syphilis, other diseases - giardiasis and toxoplasmosis.

This blood test is necessary to determine the stage of disease, evaluate effectiveness of treatment, and get information about previous diseases.

IgG - antibodies indicate past infectious disease.

IgM - antibodies indicate the presence of an acute infectious process.

Drugs associated with Infectious diseases - Tetracycline, Terramycin, Erythromycin, Ampicillin, Zyvox, Vantin, Keftab, Chloromycetin, Noroxin.