Starch agar contains high molecular weight starch molecules (soluable starch). When Iodine is added it reacts with starch to produces a dark brown/purple color. A zone of clearing forms around organisms that produce the exoenzyme amylase after addition of iodine. This plate was incubated for ... Read More
Growth of Streptococcus mitis on blood agar demonstrating alpha hemolysis seen as a greenish color around the growing colonies due to a reduction of the hemoglobin to methemoglobin in the surrounding agar. Image taken using transmitted light. Read More
This episode: Bacteria are important for a good immune response to unadjuvanted influenza vaccines!
(14.6 MB, 16 minutes)
Picture carefully taken with my iphone under a dissecting microscope. Read More
Mannitol Salt Agar (MSA)
•Important Ingredients: Phenol red, mannitol (sugar), 7.5% NaCl
•Differential: between pathogenic S. aureus and S. epidermidis
•Selective: NaCl inhibits non-halophilic organisms. Organism that can grow are halophilic.
•Mannitol Fermentors: fermentation of acid cau... Read More
Many air travelers are concerned about the risks of catching a disease from other passengers given the long time spent in crowded air cabins. New research shows disease-causing bacteria can linger on surfaces commonly found in airplane cabins for days, even up to a week. Participants discuss ... Read More
Three organisms inoculated in TSB to look at tube morphology. From left to right:
Staphylococcus aureus: flocculent growth/turbid, growth throughout the tube.
Mycobacterium smegmatis: pellicle, growth at the top of the tube. M. smegmatis tends to stick to the tube and grow up the side.
Ba... Read More
Unknown organism isolated from a swab taken off the bottom of a shoe. Students were asked to swab something in the classroom. One swab was done on the bottom of a shoe and incubated on a TSA plate for 48 hrs at 37 degree’s C. The organism was difficult to scrape so a small chunk of the organis... Read More
The following picture shows the isolated black colonies of Salmonella on Salmonella-Shigella (S-S) Agar. S-S Agar is used as a selective and differential medium for the isolation of Salmonella and some Shigella species. The inclusion of bile salts is to inhibit gram-positive organisms. Ferric ci... Read More
Nocardia asteroides isolation from blood specimen. On culture, chalky white colonies were seen on blood agar. Image courtesy MicrobeWorld user Kyriakos Zaragkoulias, Specialty Registrar (StR) in Medical Microbiology at General Hospital of Thessaloniki “G. Papanikolaou”, Greece.
Bacitracin test done on a lawn of Streptococcus pyogenes grown on blood agar. The zone of inhibition around the bacitracin disc, approx 14mm measuring the entire length of the zone, indicates sensitivity. The zone of inhibition is red because the red blood cells did not lyse. Grown for 24 hr... Read More
A streak plate of Strep pyogenes on blood agar, stock culture used for class, was kept at room temp for 1 month. Before disposal a contaminant, presumably environmental, was seen on the plate. The pigment was opaque tan/yellow and with a mucoid surface. Lobate marigins with raised irregular-rh... Read More
Methyl Red/Vogoes-Proskauer (MR-VP)
One medium used for two separate but related tests, identifying butanediol (VP) or acidic fermentation products (MR) as part of the IMViC test used in the identification of Enterobacteriaceae.
•Methyl Red (MR): detects the ability of an organism to produc... Read More
Streak plate isolation showing colonial morphology of Bacillus subtilis on trypticase soy agar (TSA) incubated for 24 hours at 37oC. Note the rough and dry/matte texture characteristic of this organism’s growth. Read More
Gram stain of B. subtilis showing characteristic G +streptobacillus morphology. Read More
Kirby-Bauer disk diffusion susceptibility test on coagulase-negative Staphylococcus aureus and E.coli grown on Mueller-Hinton agar with tetracycline (30 µg), cephalothin (30 µg), erythromycin (15 µg), chloramphenicol (30 µg), vancomycin (30 µg), penicillin (10 µg), streptomycin (10 µg), and novo... Read More
The campaign is called "Kick Back Ebola." But the posters pack a punch.
Sierra Leone has reported over 700 suspected Ebola cases, more than any other country this year. To help stop the outbreak, health workers have put up Ebola awareness signs all over Sierra Leone's seaside capital of Freet... Read More
Some holiday fun from last winter composed of different collected plate contaminants. Based on colony morphology and wet mounts, these bacteria are likely to be: Staphylococcus sp. (white), Serratia marcescens (dark orange), and Micrococcus luteus (creamy yellow). The design was incubated for 5-... Read More