Microbiology, discusses shape, structure, metabolism and all features of the organisms, and also consider relations of the diseases with this organisms.
This part of lab, has equipped with specific and modern technologies. And also has a part for taking samples from wounds, and skin lesions, nose, eyes and other parts of the body in a sterile condition.
Microbiology part of the lab also has sections such as, Microbial culture, enzymes, incubation and sterilization. Main aim of this part is to consider insanitary factors and sensitivity to them.
Such as other parts, this part has daily qualitative program, based on the health reference and standard of the laboratory, which controls by its responsible.
Doing accurate and daily qualitative control, having skillful personnel, using high and standard material along with using various microbial cultivate, offer the best diagnosis and treatment.
Following tests are done in microbiology part:
- Urine Culture & Sensitivity
- Throat Smear
- Sputum Smear (gram Stain)
- Sputum AFB Direct Smear
- Urethral (C+S)
- Urethral Smear (gram Stain)
- Vaginal Wet Prep (Direct smear)
- Vaginal discharge (C+S)
- Wound Direct smear
- Wound (Skin) (C+S)
- Wound AFB
- Breast discharge Direct smear
- Breast discharge (C+S)
This test is used to diagnose urinary tract infection in patients with dysuria, repetition and urge excretion. In men and women, urinary tract infection may be asymptomatic, acute or chronic. Infectious agent is in most cases intestinal bacilli, especially E. coli, proteus and enterococci. In 10% of infections, two bacteria may be the cause of infection. Existence of more than three types of bacteria in the culture indicates that the sample is not properly collected and contaminated.
Urine sample is better for morning urine culture.
The urine sample should be collected in a sterile loose leaf.
Before sampling, the urine pore should be washed with water and soap and after the first part of the urine, remove the urine and collect the middle part of the urine in a special container.
The urine sample should be cultured within two hours. If not possible, the crop can be stored for up to 18 hours in the refrigerator.
If a urine specimen is prepared at home, it should be transmitted promptly (within 30 minutes) to the laboratory.Sample contamination with feces, vaginal discharge, hands or clothing results in false positive results.
The use of antibiotics affects the outcome of the test.
- Calibrated loop is used for urine culture.
- Insert the loop vertically into the urethra and cultivate it as a lane in the middle of the agglutination and mechanization environment, and then spread it. After the culture of the urine environment for the clock.
- Then count the colonies on each of the plates and multiply it in the loop volume factor.
- Check the cultures after 24 hours. Incubate for 24 hours if there is no obvious growth or growth to identify very young.
- In the urine of ladies and gentlemen with a clonal number between 10 and 100 thousand tests should be repeated and if the number of colonies was the same again, an antibiogram should be performed.
- In men, 100,000 clones, even in the presence of low anti-biochemical leukocyte count, should be performed in women after antibiogram repeat testing.
Stool cultures are prescribed for patients with severe diarrhea, fever and abdominal distension. Naturally, stool contains a lot of bacteria and fungi. But bacteria such as Salmonella, Shigella, Campylobacter, Yersinia, Escherichia coli, and Staphylococcus are pathogens for the pathogenic bowel.
Use gloves when sampling and transporting feces.
Use a suitable container to collect the sample.
Transfer the fecal specimen immediately to the lab.
Urine can prevent the growth of bacteria. For this reason, stool samples should not be mixed with urine.
- The specimen should be tested and cultivated for a maximum of 2 hours after receiving the stool sample.
- If the temperature is too high and the temperature of the sample cools down, it will be reduced to pH and thus prevent the growth of many types of Shigella and Salmonella in the culture medium.
- When the stool specimen can not be tested quickly, it should be transported to the transport environment.
- To isolate the intestinal pathogenic bacteria, use appropriate selection and differential environments.
- After incubation, the growth rate, color and shape of the colonies are examined and recorded.
When the bacterial reproduction rate reaches the to level that the reticulovantothelial system can not remove them from the body, bacteremia develops. The keters are mainly from the extravascular regions and through the blood vessels through the lymphatic vessels. Naturally, fixed liver and spleen macrophages remove bacteria from the blood stream for a few minutes to a few hours, and sometimes the number of bacteria exceeds the ability of the system and septicemia occurs. Blood counts can help in the treatment of these fatal infections.
Blood samples from the patient may be taken prior to prescribing antibiotics, and the best time for blood sampling is when the patient shows signs of fever and chills.
It’s better 2 blood samples are taken at intervals of one hour from the patient and cultured.
The prepared blood culture should be immediately transferred to the laboratory and placed in an incubator (37 °).
Disinfection of the blood collection site, considering the sterile conditions during blood collection, and direct blood inoculation into the blood culture bottle, can greatly prevent contamination of blood cultures. Though, with these guidelines and in the best possible conditions, Up to 5% of the blood cultures are exposed to contamination, which can lead to skin or environmental contamination.
- Blood culture environments are available in liquid and in sealed vials. This anticoagulant medium is used to prevent clotting.
- To do culture, you must first disinfect the cap of blood culture bottles before blood transfusion. Then inject the blood into the bottle and put the blood culture bottles in a degree for about an hour.
- The bottle of blood culture should be checked regularly. Sterile cultivation is usually characterized by a layer of red blood cells that is covered by a transparent culture medium.
- Whenever the growth of the bacterium is evident in the bottle, it should be put into an aspirate bottle using a syringe and warm staining and passage are carried out on suitable environments.
- In normal cases, blood counts up to many days. But in case of suspicion of brucellosis or other hard-growing microbes, endodontic treatment or antibiotic use, the growth medium should be kept more (after weeks). After a long time, we will examine the culture media for the growth of colonies.
- Some bacteria grow unopposed, so after 24 hours and after 7 days, even without seeing the turbidity of the subculter.
- Since the rapid report of the outcome of blood cultures can be written, any results at any stages should be immediately reported to the doctor.
Sputum culture is performed to determine the presence of pathogenic bacteria in respiratory infections such as pneumonia.
The best time to do this test is at morning.
The sample for culture should be collected before starting antimicrobial treatment.
The prepared specimen should be thrown into the mouth container and kept at a refrigerated temperature and sent to the laboratory as soon as possible. Excessive sampling of the sputum out of the laboratory affects the test result.
At all stages of sampling, a disposable gloves should be used.
- Gram stain is the first phase of phlegm microbial analysis. The bacterial staining is divided into two gram positive and negative groups. This method may be used until the completion of the culture experiment to determine drug therapy.
- After culture of sputum on appropriate media and during incubation time, antibiogram is performed to identify the most appropriate antimicrobial drug treatment.
- The completion of the crop experiment requires at least 48 hours. Fungal culture and Mycobacterium tuberculosis may last for 10 to 6 weeks.
Wound culture is performed to detect the presence of pathogens in patients with suspected wound infections. Wound infections are often caused by infected organisms, which may be bacterial, fungal, or parasitic.
Prepare all necessary equipment before sampling. Devices should be sterile or disposable.
All cultures should be done before starting an antibiotic treatment.
Clean surface of the sample with 70% cotton and alcohol, remove the pus from the aspirate wound or cut it off. Then transfer the specimen into a sterile cap tube.
For swab sampling, first insert a sterile cotton swab into the aseptic wound. Then place the swab in a sterile capillary tube. (The cultivation of the sample from the skin’s edges is less accurate than the culture of purulent secretions).
For soft tissue samples and deep wounds, the wound surface should be treated with 70% alcohol and then disinfected with 2% tincture. Then, with aspiration, take the deepest part of the lesion, or pass the swab to the depth of the lesion or the edge of the lesion, and then transfer the specimen to a sterile cap tube.
If an anaerobic organism is suspected, an anaerobic culture tube should be considered. The best method is sampling, aspiration from the closed wound and direct transfer of pus to the anaerobic culture tube.
If the scarring should be taken from a disease that requires wound healing, do the sampling before wounding the wound.
- Samples of wound culture are often sent to the lab in a swab inside sterile tubes containing physiological saline. Suction sprays of the patient’s sample by flame, remove the tube and culture on appropriate media.
- If a smear is requested, a separate swap should be sent to the laboratory. If a specimen was submitted in a tube without a swab, a sterile swab for sample sampling could be used.
- After doing wound culture on suitable environments and during incubation, antibiogram is performed to identify the most appropriate antimicrobial drug treatment.
- Many wound infections contain more than one type of organism.
- Most organisms need about 24 hours to grow in the growth medium, and a preliminary report is prepared after this period. Occasionally, 48 to 72 hours are needed to grow and diagnose the organism.