macrolide resistance in BC
Since mid-1997 British Columbia has
experienced an outbreak of syphilis,
initially in heterosexuals and more re-
cently among men who have sex with
men (MSM). Starting in 1999, primarily
in patients presenting to the sexually
transmitted diseases clinic at the BC
Centre for Disease Control (BCCDC),
moist lesions of primary and secondary
syphilis were swabbed for polymerase
chain reaction (PCR) testing for
. The PCR method
used was polA gene amplification us-
ing a CDC protocol.
When the question of azithromycin
resistance arose in 2004, specimens
were examined retrospectively for the
mutation in the
gene in collaboration with investigators
from the University of Washington.
From 2000–2003, 1 of 47 positive
PCRs showed resistance in a travel-
acquired heterosexual case. In 2004, 4
of 9 positive PCRs showed the resistant
gene, all in MSM.
The 23sRNA gene correlated with
clinical resistance to azithromycin in
Dublin and San Francisco.
All of the BC patients received peni-
cillin G benzathine or doxycycline;
therefore, treatment failure with
azithromycin was not tested.
Treatment of choice in BC for early
syphilis is one dose of penicillin G
benzathine (2.4 MU intramuscularly).
Oral doxycycline therapy (100 mg twice
daily for 2 weeks)
is a second-line
treatment, with oral azithromycin ther
apy (one 2-g dose) as a third-line treat-
ent, especially in noncompliant pa-
tients who refuse injections. This se-
quence is in compliance with the
Canadian and US STD treatment
In a recent study in Africa, a 2-g oral
dose of azithromycin was as effective as
a 2.4-MU intramuscular dose of peni-
cillin G benzathine.
However, in devel-
oped countries, because of resistance
trends, azithromycin should be re-
served as a third-line treatment for
early syphilis, and patients thus treated
should be followed closely, both sero-
logically and clinically.
Muhammad G. Morshed
Hugh D. Jones
BC Centre for Disease Control
University of British Columbia Centre
for Disease Control
Department of Pathology and
University of British Columbia
1. Hsi L, Rodes B, Chen CY, et al. New tests for
syphilis: rational design of a PCR method for de-
in clinical speci-
mens using unique regions of the DNA polymerase
J Clin Microbiol
2. Lukehart SA, Godornes C, Molini MS, et al.
Macrolide resistance in
United States and Ireland.
N Engl J Med
3. Health Canada.
Canadian STD Guidelines
4. US Centers for Disease Control and Prevention.
Sexually transmitted diseases treatment guidelines
MMWR Recomm Rep
5. Riedner G, Rusizoka M, Todd J, et al. Single-dose
azithromycin versus penicillin G benzathine for
the treatment of early syphilis.
N Engl J Med
Competing interests: None declared.
In an article by Michelle Graham and
an attempt was made to
determine optimal catheterization rates
by detecting the population rate of car
diac catheterization beyond which the
yield of high-risk coronary artery dis-
ase does not rise. However, some is-
sues are not quite clear. First, the au-
thors did not explain why they expected
to identify such a phenomenon in
Canada, a country with medium
catheterization rates, when they did not
mention any plateau effect in countries
with higher catheterization rates.
Second, the authors suggest that the
highest regional average catheteriza-
tion rates for men (638 per 100 000
population) and women (314 per
100 000 population) are lower than op-
timal catheterization rates. However,
higher rates of catheterization have al-
ready been reached in several regions
considered in this study for men and
for women (Fig. 3 and Fig. 4 in the arti-
and there are reportedly no signs
of a plateau effect. It is not clear why
those higher values were not consid-
ered as the rates that are also lower
than optimal catheterization rates, be-
cause that would be in accordance with
the applied method of detecting an op-
timal rate of catheterization.
Department of Biophysics
University School of Medicine
Graham MM, Ghali WA, Faris PD, et al. Population
rates of cardiac catheterization and yield of high-
risk coronary disease.
[The authors respond:]
We thank Milorad Letic for his interest
in our paper. We embarked upon this
research because the concept of a
plateau in detection of high-risk coro-
nary disease is only theoretical, and no
previous studies have determined
whether a plateau actually exists. We
chose to use regional catheterization
rates from Alberta because of the avail-
ability of rich population-based data to
perform this analysis. The highest re
gional average rates that were used in
CMAJ • January 31, 2006 • 174(3) | 349
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