120
There is, however, one feature of the Vi curve in typhoid which seemed
to distinguish it from the non-specific Vi curves not infrequently encountered
in other diseases. The true Vi curve usually showed a definite rise and fall,
though the peak may not have been very high: whereas the non-specific
curve may be high to start with, but in subsequent tests showed a gradual or
rapid fall—there was no ascending to a peak. This characteristic was parti
-cularly noticeable in cases of typhus, where a relatively high Vi titre was
frequently noted in the initial stages of the fever.
Investigations on the above lines are being continued and it is again
pointed out that any conclusions drawn from the above are only tentative.
Isolation of Enteric Group organisms from blood culture.—A total of 4,642
blood cultures were taken during the year from cases suspected to be suffer
- i n g f r o m e n t e r i c g r o u p i n f e c t i o n s . T h e f o l l o w i n g i s a s u m m a r y o f s u c c e s s f u l
isolations. B. Typhosum 79, B. paratyphosum A 34, B. paratyphosu M B 3,
and B. paratyphosum C 1. The average day of isolation was the 6th day after
the onset of the disease.
Of the total cultures 11 per cent were found to be contaminated which
is a marked reduction from last year when the percentage was 16.
In last year's report it was explained that sodium taurocholate medium
containing gentian violet in a dilution of 1—16,000 had been recommended
for use by all laboratories as a means of reducing the number of contamina
-tions. The results on the whole have been most satisfactory. In one labora-
tory percentage of contaminations was only 1 . 7 when gentian violet was em
- p l o y e d , w h e r e a s i n t h e c a s e o f p a r a l l e l c u l t u r e s t a k e n w i t h o u t t h e a d d i t i o n
of the dye, the percentage was 14 . 4. Another laboratory adopted the practice
of testing blood cultures first, and then, if found to be contaminated sufficient
Gentian Violet was added so as to obtain the necessary concentration of the
dye. Employing this method B. typhosum was isolated five times from blood
cultures found to have been contaminated by a staphylococcus. One labora
-tory which did not use gentian violet was rewarded with a contamination rate
of 20 per cent which markedly increased the all-India percentage.
It has been pointed out to all officers commanding laboratories that media
containing gentian violet is only suitable for use in cases of suspected enteric
group infection, and that, as a routine, blood should also be inoculated into
glucose broth or some similar medium.
The reduction of contaminations by 5 per cent during the year under
review is mainly attributed to the use of this dye.
Isolation of Enteric Group organisms from faeces and urine .—The isolations
of enteric group bacilli from faeces were 46 (B. typhosum 28, B. paratyphosum
A 16, and B. paratyphosum B 2). This figure is smaller than last year when
there was a total of 61 isolations and also a greater number of isolations from
blood culture. It is still felt however that apart from any defective technique
in the collection of specimens in hospitals for despatch to laboratories, it is
difficult to isolate organisms from heavily inoculated individuals who may be
suffering from the disease.
All British troops diagnosed Enteric Group of infection during the year
were again automatically sent to the Enteric Fever Convalescent Depot,
Kasauli, for examination and test for a carrier condition, as, during last year
in no case was any pathological organism isolated from any of these convales
- c e n t s .