In this Energy Code Deep Dive, we review a real-world, high-stakes study that sounds like sci-fi: using methylene blue + a specific wavelength of light to kill antibiotic-resistant bacteria. The clinical backdrop is pediatric perforated appendicitis, where bacteria can leak into the abdomen and lead to serious infections, long hospital stays, and heavy IV antibiotic use.

The paper tests photodynamic therapy (PDT): add a light-sensitive dye (methylene blue), shine 665nm light, and generate reactive oxygen species that inflict broad oxidative damage on microbes—often regardless of classic antibiotic resistance mechanisms. The results are striking for several major pathogens, with huge log reductions for E. coli and Streptococcus anginosus group, and more variable results for Pseudomonas aeruginosa.

We also keep it grounded: it’s in vitro, not yet a clinical protocol, and it didn’t test everything you’d want (biofilms, polymicrobial mixtures, anaerobes). But as a proof-of-concept, it’s a strong argument that light can be a precise medical tool—when parameters are engineered, not guessed.

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Article Discussed in Episode:

Photodynamic therapy with methylene blue effectively kills antibiotic resistant bacteria from pediatric patients with perforated appendicitis

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Key Quotes From Dr. Mike:

“Photodynamic therapy doesn’t rely on the same mechanisms as antibiotics, so it can work even when bacteria are resistant.”

“You take a dye that’s light sensitive… add it to the bacteria, then you shine a specific wavelength of light.”

“Methylene blue is the match, the light is the strike.”

“A 6-log reduction is a millionfold reduction… basically a wipeout in this kind of lab setup.”

“The key takeaway is resistance didn’t protect bacteria from this approach in most cases.”

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The study targets a big clinical problem: perforated appendicitis in kids → intra-abdominal infection risk, long hospitalization, heavy antibiotic exposure.

The intervention is photodynamic therapy (PDT): methylene blue + 665nm light → reactive oxygen species that damage bacteria.

PDT doesn’t rely on standard antibiotic mechanisms, so it can work even when bacteria are antibiotic-resistant.

Methods: bacteria isolated from peritoneal fluid samples (30 patients) and tested under 4 conditions: control, dye-only, light-only, dye+light.

Parameters matter: 665nm laser via fiber optic; low fluence rate (4 mW/cm²), total fluence 7.2 J/cm², 30 min; methylene blue 300 mcg/mL.

Most prevalent organisms included E. coli, Strep anginosus group, Bacteroides fragilis, Pseudomonas aeruginosa; polymicrobial infections were common.

Results: ~5.86–5.91 log₁₀ reductions for E. coli and Strep anginosus group (massive kill); Pseudomonas showed smaller, variable reductions (~2.23 log₁₀).

Limitations: in vitro, planktonic monocultures (not biofilms/mixed communities), anaerobes not tested in PDT setup, and parameter optimization still needed—yet the proof-of-concept is very promising for a localized surgical adjunct.

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0:19 — Intro sting + welcome back

0:32 — Topic hook: methylene blue + light vs antibiotic-resistant bacteria

1:06 — Clinical context: pediatric perforated appendicitis → infections, IV antibiotics, long stays

1:49 — PDT explained simply (dye + light → ROS; works beyond antibiotic resistance)

2:39 — Study design: 30 patient samples; isolate bacteria; 4 test conditions

3:13 — Technical parameters: 665nm laser/fiber optics; dosing details; why specs matter

3:50 — What bacteria were found; polymicrobial reality + resistance common

4:36 — Results: major kills for E. coli & Strep; Pseudomonas more variable

5:13 — Quick “log reduction” translation for normal humans

6:16 — Resistant vs susceptible strains: resistance didn’t protect (most cases)

6:54 — Big vision: localized surgical adjunct via laparoscopic illumination

7:24 — Limitations: in vitro, monocultures, no biofilms/mixed species, anaerobes not tested, optimization needed

8:19 — BioLight tie-in (light as precise tool; don’t wing it; specs matter)

9:29 — One-sentence takeaway

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