No. c.c. of 1 per cent. Formamint00.10.30.50.71.01.52.03.0
Count1603339261512200

Another experiment was made thus: One loopful of a twenty-four-hour plain agar culture of Strepto­coccus lacticus was mixed with a tube of North medium. One loopful from the inoculated tube was mixed with a second tube of North medium. Both tubes were poured into Petri dishes and allowed to cool. One half of each plate was well smeared with a 10 per cent. solution of Formamint in saliva. After twenty-four hours’ incubation at 37 C., only a few colonies appeared on the side to which the Formamint had been applied, while the other half was thickly covered with colonies.

This work so far corroborates that reported in the literature quoted by the manufacturers. But the fact that a compound is a germicide when brought into intimate contact with bacteria in a solution or medium in a test tube or flask does not prove that it will be effective when used in the human throat.

THE ALLEGED GERMICIDAL ACTION

An attempt was made to discover whether or not the claims advanced by the manufacturers as to the perfect germicidal action of Formamint in all the nooks and crannies of the mouth and throat could be confirmed.

The first step in attacking this problem was to make comparative counts of the number of bacteria in the throat before and after the use of Formamint. The methods employed were as follows: The throat was gargled with 50 c.c. of sterile 0.85 per cent. sodium chlorid solution. In each case the same length of time, as far as possible, was used in the process. The liquid was collected in a sterile flask. The gargling in a series of experiments was begun not less than two hours after a meal. After some preliminary work the following dilutions of the 50 c.c. of salt solution were found sufficient: 1:1,000, 1:10,000 and 1:100,000. Plates were made in duplicate from each dilution and incubated seventy-two hours at 37 C. The counts were made on plates containing less than 200 colonies. Except where otherwise noted standard agar was used. The mediums were always prepared in the same way.

All the work was carried out under conditions as nearly natural as possible. The Formamint was taken according to the directions accompanying the trade package. Every opportunity was given the Formamint to penetrate all the crypts and recesses about the mouth and throat. The tablet was allowed to dissolve as slowly as possible, the time usually being five to six minutes, and saliva was thoroughly forced around the mouth before being swallowed. Plating was always done immediately after gargling so that no growth could occur in the salt solution. The results are given in Table 3. The numbers are average counts from several plates and calculated to show the number of bacteria washed out by the 50 c.c. of salt solution.

TABLE 3.—SHOWING THAT FORMAMINT DOES NOT GREATLY DECREASE THE NUMBER
OF BACTERIA IN THE THROAT

Conditions of Test
 		Time Since
Preceding
Test		Amount of
Formamint
Used		No. Found
in Throat
Before Use of
Formamint		No. Found
in Throat
After Use of
Formamint
Normal...015,600,000...
Normal1 hour038,500,000...
Normal1 hour030,500,000...
Normal...012,500,000...
Normal1 hour014,500,000...
1 hour023,500,000...
Tablet dissolved in mouth and throat gargled one hour later6 days1 tablet...15,000,000
Throat again gargled two hours after Formamint was used1 hour0...10,050,000
Normal7 days062,000,000...
Normal1 hour072,500,000...
Normal......61,000,000...
Tablets were taken, one per hour, and throat gargled one hour after last tablet was taken2 days12...39,100,000
Throat was again gargled 2 hours after taking last tablet1 hour0...59,000,000
Normal5 days035,000,000...
Normal1 hour062,000,000...
Normal1 hour072,000,000...
One tablet was taken each half hour for twelve hours consecutively. Throat was gargled one hour after last tablet was taken4 days  24 tablets  ...175,000,000
Throat was again gargled two hours after last tablet was taken1 hour0...168,750,000
Normal3 days0129,600,000...
Normal1 hour0177,000,000...
Normal1 hour0147,000,000...
Normal3 days079,000,000...
One tablet was taken immediately after preced­ing gargle. Throat was again gargled at end of one hour1 hour1...83,200,000
Throat was again gargled two hours after tablet was taken1 hour0...134,750,000
Normal conditions except that mouth and teeth were throughly washed with soap just before gargling  19 days032,600,000...
Same as above1 hour033,125,000...
Same as above1 hour040,375,000...
Teeth were not washed. Otherwise normal conditions2 days033,500,000...
Same as above1 hour043,330,000...
Same as above1 hour054,000,000...
Same as above1 hour050,000,000...
Same as above1 hour067,000,000...
Mouth and teeth thoroughly washed with soap just before throat was gargled2 days05,270,000...
Same as above1 hour010,916,000...
Same as above1 hour08,275,000...
Normal conditions, but 1 c.c. of sterile rabbit’s blood was added to each plate3 days0228,750,000...
Count from the same gargle as above. No blood used in the plates0060,625,000...
Normal conditions, but count was made on blood agar1 hour0 431,250,000...
Count from the same gargle as above. No blood used in the plates0059,625,000...
Normal conditions, count was made on blood agar2 days0  683,300,000...
Same gargle as above, but count was made on plain agar0058,500,000...
One tablet was taken just after preceding gargle. After one hour throat was again gargled. Count on blood agar1 hour1 tablet...558,300,000
Same gargle as above, but count was made on plain agar01 tablet...55,875,000
Normal conditions2 days079,125,000...
One tablet was taken just ten minutes before gargle was made1 hour
16 min.		1 tablet...56,250,000
Normal conditions2 days046,750,000...
One tablet was taken just ten minutes before throat was gargled1 hour1 tablet...38,500,000
Teeth and mouth were thoroughly washed with soap just before gargle was made5 days047,370,000...
Teeth washed as above and one tablet taken ten minutes before gargle was made1 hour1 tablet...21,225,000