A reader forwarded me a study and some of it was interesting hints on this issue.
In vitro experimental results show a potent inhibitory effect (greater than 90%) of chloroquine, a historical antimalarial active ingredient, and clavulanic acid, a β-lactam antibiotic widely used in combination with amoxicillin . A significant inhibition of the enzymatic activity has also been observed with the antihypertensive drug verapamil and the histamine H2 receptor antagonist cimetidine, although the clinical use of the latter is currently anecdotalHistamine Intolerance: The Current State of the Art 
My idea is to examine which bacteria these items impact and see if there is a pattern.
The full list is below
|Diclofenac||Analgesic and anti-inflammatory|
|Cimetidine||Antihistamine (H2 antagonist)|
|Prometazina||Antihistamine (H1 antagonist)|
|Ascorbic acid||Vitamin C|
We have 14 items that we have data on.
At the family level, the following at the commonly impacted — all were decreased.
- Bacteroidaceae – 14
- Desulfovibrionaceae -14
- Enterobacteriaceae -13
- Clostridiaceae -13
- Peptostreptococcaceae -13
At the genus level we have these all at 14 matches and decreasing
There are no clear smoking guns. When we include Special Study: Histamine or Mast Cell Issues we see that histamine issues are associated with lower levels of many bacteria (where as the above are those implicated in higher levels). We also looked at histamines in Exploration: Salicylate Sensitivity And the Microbiome, where we see under detection usually being the characteristic for histamine issues (except for Rothia mucilaginosa.
Doing cross checking, we find that the following are not reported impacted by the above AND are low in the other studies:
- Methanobacteriaceae (family) – none
- Heliobacteriaceae (family) – none
- Anaeroplasmataceae (family) – none
- Desulfocella (genus) – none
- Spirosomaceae (family) – none
- Rhodocyclaceae (family) – none
- Cytophagaceae (family) – none
- Ezakiella (genus) – none
- Halobacteroidaceae (family) – none
- Burkholderiaceae – only 1 impacts
- Limosilactobacillus – only 10 impacts
All of the “none” are most likely due to this family or genus not be measured in the studies used. This leaves one bacteria of interest: Burkholderiaceae.
We have no clear pattern. The drugs at the top likely makes room for bacteria that are low in frequency and amount to grow. Our attempt to find the bacteria ignored by the drugs above AND which are seen at low levels only turned up one candidate with a manual review: Burkholderiaceae.
Writing code to drill deeper may find more — stay tune.