Aerobic – Anaerobic Microorganisms
Microorganisms, usually bacteria, are often detected in biological fluids, which in some cases, can become pathogenic. Bacteria are prokaryotic organisms that come in many forms and shapes. Microorganisms are divided into aerobic, which need oxygen to live, and anaerobic, which are killed if oxygen is present in their environment.
Detection of microorganisms is commonly done on semen or urine samples by culture. The sample to be tested is spread on the petri dish, that contains nutrients such as blood agar, Mc Conkey and Sabouraud agar. Pathogenic microbes such as Escherichia coli, Proteus, Pseudomonas, Klebsiella, Staphylococcus aureus, Enterococcus, Staphylococcus epidermididis can be detected, which will be considered potentially pathogenic if they exhibit great growth in culture.
In cases of positive culture, in other words when a microorganism grows in culture and forms many colonies, another test, the antibiogram, must follow. At the antibiogram different antibiotics are tested to determine which is the most effective. The doctor relies on the antibiogram in order to choose the right medication.
MYCOPLASMA – UREAPLASMA
Mycoplasma (Mycoplasma hominis) and ureaplasma (Ureaplasma urealyticum) are two bacteria that belong to the mycoplasma family and are present in the reproductive system of a large percentage of sexually active people. In men, these microorganisms are also isolated in prostatic secretions.
Both of these microorganisms are also sexually transmitted and can cause a variety of clinical syndromes such as urethritis and prostatitis, pain and stinging when urinating, as well as swelling and pain of the epididymis. In most cases, however, mycoplasma or ureaplasma infections are asymptomatic.
Mycoplasma and ureaplasma are usually detected by a biochemical semi-quantitative method. In this method the semen sample is incubated with a reagent containing arginine and urea. If the test sample is contaminated with mycoplasma and ureaplasma, then the urea and arginine are broken down and the solution changes color. If the amount of mycoplasma or ureaplasma exceeds the concentration of 104 CFU / ml within 24 hours, the test isconsidered positive. The method does not have high specificity and has a high percentage of false positive result.
Both mycoplasma and ureaplasma are more reliably detected by culture in the specific and selective growth medium A7. The culture, according to protocol, should be incubated for 3-5 days. This culture detects Mycoplasma Hominis and Ureaplasma Urealitycum as well as Mycoplasma Fermentans which develops after 5 days of incubation.
Culture in this case can be considered a good choice because an antibiogram can be performed. The antibiogram in this case makes use of a special plate of adsorbed antibiotics in different concentrations, specific for the specific microorganisms. Choosing the right antibiotic, as already discussed, is important information for the doctor to determine the right treatment.
However, the method of detection of mycoplasma and ureaplasma that presents with the greatest reliability in the molecular method, the Polymerase Chain Reaction (PCR), which detects the genetic material of microorganisms. All types of mycoplasma, Mycoplasma Hominis as well as Mycoplasma Genitalium and all types of ureaplasma, Ureaplasma Urealyticum and Ureaplasma Parvun can be detected by PCR with great sensitivity and specificity.
Chlamydia (Chlamydia trachomatis) are bacteria that infect the reproductive system. Chlamydia is generally a “silent disease” as 50% of infected men have no symptoms. It is the most common sexually transmitted infection and the World Health Organization (WHO) had announced that there were 92 million people with chlamydia in the world for 2001 and 127 million for the year 2016 !!! World Health Organization. (2001)
In men, chlamydia cause symptoms similar to those of gonorrhea and they appear in one to three weeks. Occasionally there may be some unusual discharge from the penis (milky white or yellow liquid) or a burning sensation when urinating. Rarely, there may be pain or swelling in one or both testes.
Chlamydial infection adversely affects sperm function resulting in infertility or miscarriage. It is important that the laboratory method be able to detect chlamydia so that targeted treatment can fight the infection and optimize both natural conception or attempts with assisted reproduction.
There are many methods for detecting chlamydia, the most common being a) the latex pellet method and b) direct immunofluorescence, which uses fluorescein-bound monoclonal antibodies (FITC) against a specific chlamydial protein. These methods detect chlamydia, but with little sensitivity.
In contrast, molecular methods such as the polymerase chain reaction (PCR) method are sensitive and therefore reliable. The PCR method is based on the detection of chlamydial genetic material (DNA) that may be present in a sample.
Initially, the genetic material is amplified and thus chlamydia can be detected even in samples with a small amount. Although a very small percentage of sperm samples may have polymerase inhibitors – the enzyme used in the PCR method – which can be responsible for faulse negative results, PCR detection is by far the most reliable method of determining chlamydia.
In recent years, chlamydia has also been detected with the SPI ™ (SpermPathogen Immunophenotyping) test. The spermatozoa are first fixed, holes are made on their membrane and then a special treatment follows. They are then incubated with antibodies – specific to the pathogen – and finally the intracellular expression of the microorganisms is analyzed and evaluated by flow cytometry, in a large cell population.
In the sperm sample the SPI Test ™ is used to detect not only chlamydia but also other viruses (cytomegalovirus and herpes) and it has the following advantages :
- High sensitivity
- Ability to accurately locate microbes inside or on the membrane of spermatozoa, as well as the type of cell in which the microorganism is detected, ie spermatozoon or other cell type
- Cheaper price
- Possibility of sending the sample to be tested, after consultation with the laboratory.
The SPI Test™ is protected by copyright legislation and is provided exclusively at Locus Medicus medical centre and Zeginiadou-Andrology laboratory.
Methods for the detection of microorganisms
Detection of HPV, HSV, CMV viruses