The document discusses microbiology cultures and antibiotic sensitivity testing. Cultures can detect microorganisms causing infections in different body parts, and sensitivity tests identify the most effective antibiotic. Various sample types can be cultured on different media like blood agar or MacConkey agar. The procedure involves collecting samples, culturing on media, and incubating to observe growth. Sensitivity testing involves spreading bacteria on nutrient agar, placing antibiotic disks, and measuring inhibition zones to determine antibiotic effectiveness.

1. Microbiology partition Prepared by Mostafa Salah El- Din Biochemistry division Cultures and Sensitivity

2. 1) The cultures : can be used to detect the microorganisms Which cause an infection in any part of the body such as ; urinary tract , throat, GIT, ear, eye and the respiratory tract; etc . 2) The sensitivity test : can be used to detect the most effective antibiotic against the microorganism that cause a certain infection.

3. 1) Urine culture. 2) Stool (Fecal) culture. 3) Blood culture. 4) Sputum culture. 5) CSF culture. 6) Pus (Wound) culture. Types of cultures

4. 7) Semen culture. 8) Prostatic culture. 9) Vaginal culture (swab). 10) Cervical culture. 11) Nasal culture (swab). 12) Eye culture (swab). 13) Ear culture (swab). 14) Throat culture (swab).

8. 4) Mackonkey medium : a) 12.8 g of Mackonkey powder dissolved in 250 ml distilled water. b) Boiling in an oven or on a hot plate. c) Leave it for cooling in the air. d) After cooling, store in the refrigerator for use.

10. c) Any of other samples can be cultured on the following 3 media : 1) Blood agar medium. 2) Chocolate agar medium. 3) Mackonkey medium.

11. 1) Sample collection ( from the part where the infection occur) in a sterile container. 2) Pour the suitable previously media in sterile Petri dishes. Example : If the sample is stool, SS agar medium and Mackonkey medium should be poured in Petri dishes. 3) Leave the dishes for 10 minutes to make the media solidified. Steps of culturing

12. 4) Immerse a sterile swab in the container which containing the specimen, then roll the swab on the surface of a solid medium And spread the specimen in a corner of the dish by the swab, pull the specimen in 3 lines on the surface of the medium by the swab, then pull the 3 lines into another 3 lines (perpendicular to the previous 3 lines), finally draw a zigzag line by the swab on the medium( See Fig.1) . 5) Incubate the cultures at 37 C° for 24-48 hours in an incubator. 6) Observe the results :

13. a) If the growth occur on all media; hence the sample was infected with a gram positive bacteria. b) If the growth occur on Mackonkey medium only; hence the sample was infected with a gram negative bacteria . Notes : 1) All the above steps must be performed under sterile conditions ( near to the flame). 2) Don't pour the medium in the dish until cooling and before solidification. 3) Don't speak during the culture.

14. Figure 1 : Fourth-way streak method

16. 2) Then by the swab, spread the loop on a nutrient agar medium in 3 direction to ensure confluence 3) By using a dispenser, antibiotic-impregnated disks are placed onto agar surface ( See fig. 2). 4) As the bacteria on the lawn grow, they are inhibited to varying degrees by the antibiotic diffusion from the disk. 5) It has been determined that zones of inhibition of a certain diameter ( varies for antibiotic and to a lesser extent, bacterial species) correlate with sensitivity or resistance to the antibiotic tested.

17. Figure 2

18. 6) Incubate the culture at 37C° for 24 hour in an incubator. 7) Observe the results. Note : the larger the inhibition zone, the more the sensitivity the antibiotic (See fig. 3) Figure 3