Greetings my Little Gang of Nasties 😈😜 Today we’re breaking down the basics of Gram-positives vs Gram-negatives in Microbiology. Attached, you’ll find two flow charts: use these as much as you can when answering your practice questions. The more you use them, the faster it’ll become second nature when you see those bacteria show up on your exam. 🦠 Gram-Positives (Purple!) • Cell wall: Thick peptidoglycan layer → holds onto crystal violet stain. • Examples: Staphylococcus, Streptococcus, Bacillus, Clostridium, Listeria. • Biochemicals you’ll use a lot: Catalase, Coagulase, Hemolysis patterns, Bile esculin, 6.5% NaCl, Optochin & bacitracin sensitivity 👉 TSI Slant for Gram-Positive Rods (like Bacillus or Listeria): usually A/A (acid slant/acid butt), but Clostridium can be variable depending on species. 🦠 Gram-Negatives (Lactose and Non-Lactose Fermenters) • Cell wall: Thin peptidoglycan layer + outer membrane with LPS. • Examples: Enterobacteriaceae (E. coli, Salmonella, Shigella, Klebsiella), Pseudomonas, Neisseria, etc. • Biochemicals to remember: Oxidase, Indole, Urease, Citrate, H2S production. 👉 TSI Slant for Gram-Negative Rods: • E. coli: A/A (acid slant/acid butt), gas, no H2S • Salmonella: K/A (alkaline slant/acid butt), H2S positive • Shigella: K/A, no H2S • Klebsiella: A/A, gas • Pseudomonas: K/K (alkaline slant/alkaline butt) = non-fermenter 🔑 Tip: Your flow charts and TSI reactions are your cheat codes. Use them over and over until you don’t even need to think… you’ll just know the answer. Now go run through some practice questions using the charts. The more you do, the more this sticks, and the faster you’ll dominate your exam. -Marilyn 🧪✨ Interested in studying with other students for your ASCP exam? Weekly study session available in the Inner Circle of Microscope Views. Click here to join now, or book a 1:1 call with me to assess your needs! https://www.skool.com/microscopeviews/about?ref=badbb26c40a147eea94634972a25414a

👋🏾 Hello, my little Gang of Nasties! I’m really glad you’re here. This space was made specifically for students and future lab professionals who are trying to study smarter, stay motivated, and finally pass the ASCP exam without losing their minds. Whether you’re still in school, prepping for boards, or coming back after a break—this is your space. 👇 Introduce yourself to our FREE Community: 1. What’s your name? 2. Where are you in your lab journey (Student? Graduated already?) 3. Which department is your biggest struggle? 4. Which department is your favorite? I’ll go first… My name is Marilyn, aka @marilynthescientist 👩🏾‍🔬 I’m a Clinical/Medical Laboratory Scientist with 10 years of experience in the field. 💉 I’ve worked everywhere—from tiny Critical Access Hospitals to busy Level 1 Trauma Centers. 🧳 6 of those years were spent traveling across the U.S. 🩸 Currently, I’m holding it down as a Blood Bank Supervisor in California. This space is here for us to learn, laugh, rant, and master the lab world together. No dumb questions, EVER! 📲 Follow me on socials if you want extra lab tips, rants, and ratchet breakdowns: Instagram | TikTok 🧬 If you ever have questions—even the “silly” ones—DM me or post them in the group. 😤💅🏾