Our clinical bacterial culture and antibacterial testing service offers a comprehensive solution for identifying the sensitivity of bacteria to new substances and searching for new antibacterial substances and drugs. We employ standardized methods and correct inoculum preparation techniques, determining inoculum size, growth medium, incubation conditions, and endpoints. These factors greatly contribute to the accuracy and reliability of antibacterial tests, enabling researchers to compare results effectively.

The test fee for our service varies depending on the type of sample and test conditions requested. To provide an accurate estimate, we will generate a preliminary invoice in response to the applicant's initial email.

This method involves preparing an antibacterial solution and pouring it onto TSA or MHA medium. As the antibacterial solution gradually diffuses into the culture medium, it destroys bacteria in its surroundings, resulting in the formation of a zone of inhibition where no bacterial growth occurs. This method is useful for determining whether a substance possesses antimicrobial properties. It's important to note that sample preparation methods may vary depending on the substance or product being tested.

The agar well diffusion method is commonly employed to investigate the antimicrobial activity of various extracts. Similar to the disc diffusion method, a microbial suspension is spread evenly on the surface of an agar plate. Subsequently, under sterile conditions, a hole with a diameter of 6 to 8 mm is created in the agar, and a specific volume (100-200 μl) of the sample (extract) with a defined concentration is placed in the well. The agar plate is then incubated under appropriate conditions based on the type of microorganism being tested. The antimicrobial agent present in the sample diffuses into the agar and inhibits the growth of the tested microbial strain.

MIC determination method involves using ten test tubes, each containing 500 microliters of autoclaved TSB culture medium. Starting with tube number one, the sample is added for dilution, mixed thoroughly, and then 500 microliters of the diluted sample from tube number one is transferred to tube number two. This process is repeated until tube number seven. After shaking tube number seven, 500 microliters of the solution is discarded. Next, a specific quantity of a bacterial suspension, equal to half McFarland turbidity, is added to all seven tubes, resulting in a final bacterial concentration of approximately 5 x 105 CFU/mL. Tube number eight serves as a control with sample + TSB medium, tube number nine contains TSB medium + bacteria without the sample (positive control), and tube number ten contains only TSB medium (negative control) to assess the turbidity of the medium in the absence of bacterial growth. The MIC result is determined based on the turbidity of the culture medium and can be read using a spectrophotometer at a wavelength of 600 nm, which indicates bacterial growth.

Inhibiting bacterial growth does not necessarily indicate bacterial death. The distinction between the bacteriostatic and bactericidal effects of an antibiotic lies in the antibiotic's ability to reach its molecular target. The MBC is the minimum concentration of the sample that effectively kills bacteria. After determining the MIC, 10 microliters of each tube is plated onto TSA or MHA culture medium. These plates are then incubated at 37 °C for 24 hours. The test results are reported by counting the number of colonies that appear (ranging from one to ten colonies).

Colony-Forming Unit (CFU) Counting Method:
Each colony represents a mass of bacteria that originated from the growth of a single bacterial cell on a solid medium. Therefore, the number of colonies can be used as an estimation of the initial number of bacteria in the suspension. CFU calculation involves multiplying the average number of counted colonies from at least two plates by the dilution factor used. It is recommended to count a minimum of 30 and a maximum of 300 colonies from a properly diluted sample plate.

Laboratory Supervisor:

Dr. Mohammad Reza Nejadmoghaddam; Email: moghaddam @avicenna.ac.ir

Somayeh Najafzadeh (BSc in Laboratory Science); Email: n.najafzadeh @avicenna.ac.ir; Contact Number: +98 (21) 22432020 - Extension 106

The laboratory is situated on the ground floor of Avicenna Research Institute, located within Shahid Beheshti University.

The laboratory operates from Saturday to Wednesday, between 8:00 AM and 4:00 PM.

The cost of tests or services will vary depending on the sample type and specific testing requirements. Therefore, upon the initial inquiry, the laboratory will provide information regarding the cost of the requested test.

To ensure smooth processing, please coordinate with the laboratory assistant at least 48 hours before sending the sample.