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| Journal of the New Zealand Medical Association,
26-September-2003, Vol 116 No 1182
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Pre-hospital antibiotic treatment of meningococcal disease:
scope for improvement
Tania Riddell and Chris Bullen
New Zealand is in its twelfth year of a serogroup B
meningococcal disease epidemic. In 2002, the epidemic showed no sign of abating
and trials aimed at controlling it by using a strain-specific vaccine began.
However, it could be another two years before national mass vaccination begins.
Even with a vaccine, pre-hospital antibiotic treatment of suspected cases of
meningococcal disease is essential. The case fatality rate for patients seen by
a doctor and given antibiotic treatment prior to hospitalisation is
significantly lower than for patients who do not see a doctor and do not receive
parenteral antibiotics.1–3 In New
Zealand, pre-hospital antibiotic treatment is given to only about one quarter of
suspected meningococcal disease cases.4 This
study aimed to determine the extent to which Auckland GPs follow Ministry of
Health guidelines that advise them to administer parenteral antibiotics
to:
MethodsRetrospective audit of all
cases of meningococcal disease in Auckland for the 12-month period 1 May 2001 to
30 April 2002.
Cases were identified through EpiSurv – the
national database for notifiable diseases.
Figure 1 gives the case definition for meningococcal
disease.
Figure 1. Definition of case of meningococcal
disease
PCR = polymerase chain reaction; CSF = cerebrospinal
fluid
All notified Auckland meningococcal disease cases (both
confirmed and probable) were included in the study. The audit included those
cases who were referred by a GP to hospital and subsequently diagnosed with
meningococcal disease. Cases were classified as ‘eligible’ to have
received pre-hospital parenteral antibiotics if they met with Ministry of Health
guideline criteria.
Auckland Regional Public Health Service records were
used to obtain case details. Permission to review records was obtained from
supervising consultants and the Auckland Ethics Committee determined that ethics
approval was not required.
A standard ‘proforma’ was used to extract
the following information:
Practice nurses were contacted by
telephone and asked if the travel time from their practice to the nearest
appropriate hospital was greater than 30 minutes.
A rate ratio was calculated for the variables: age,
sex, ethnicity, presence of a rash and general practice greater than 30 minutes
away from the admitting hospital. Adjustment for possible confounding factors
was carried out using the Mantel–Haenszel method. Cases for which the
relevant data were unknown were excluded from analysis. Statistical analysis was
carried out using EpiInfo 2000.5
ResultsOver the 12-month study period, 214
cases were recorded on EpiSurv as having been admitted to Auckland hospitals
with meningococcal disease. About two thirds of these cases (n = 142) were
referred to hospital by a GP. One hundred and eleven (78%) cases were eligible
for pre-hospital antibiotics according to Ministry of Health guideline
criteria.
The median age of the GP-referred cases was six years (range
28 days to 67 years) with over half of cases (55%) under five years old. Eighty
three cases (58%) were male. There were 58 (41%) Pacific Islands people, 40
(28%) Europeans, 36 (25%) Maori, and eight (6%) of ‘Other’ ethnic
groups.
Of the 111 eligible cases, 33 (30%) were given parenteral
antibiotics by their attending GP. Of the 79 cases (56% of all the cases
referred) reported to have a rash, only 31 (39%) received antibiotic treatment.
Thirty two (28%) of the eligible cases were referred from practices where the
delay to assessment in hospital was estimated to be greater than 30 minutes. Of
these, only nine (28%) received pre-hospital antibiotic treatment.
Cases with a rash were twice as likely as those without a
rash to have received pre-hospital antibiotic treatment (RR 2.1; 95% CI
1.7–2.7). In fact, of the 33 cases overall who were administered
antibiotics, 31 (94%) had a rash. There was no difference in antibiotic
administration by age, sex, ethnicity or distance of general practice from
hospital.
DiscussionThis study suggests there is scope
for improvement to the pre-hospital management of suspected cases of
meningococcal disease in Auckland. Despite regular advice urging the
administration of parenteral antibiotics prior to hospital
admission,7–9 this study found that in
Auckland only one third of eligible patients were given treatment by an
attending GP. Furthermore, parenteral antibiotics were rarely given in the
absence of a rash, even for those in whom the delay to assessment in hospital
was likely to be greater than 30 minutes.
A number of reasons have been postulated to explain the
failure to start early treatment for suspected meningococcal disease in the
primary care setting. These include diagnostic uncertainty, concern about
interference with hospital tests, the belief that patients will be treated
promptly once in hospital, fears of administering unnecessary treatment or
causing an anaphylactic reaction, and unproven
benefit.10
Diagnostic uncertainty is common in general practice where
many diseases are encountered at early stages when signs and symptoms are often
non-specific.11 The diagnosis of meningococcal
disease is largely a clinical one as highlighted by the case definition (Figure
1). The petechial or purpuric rash of meningococcal septicaemia is a physical
sign that can assist early suspicion of
infection.12 In this study, the presence of a
rash was the most important factor that led to administration of antibiotic
treatment prior to hospital admission. This supports the findings of other
studies.11–13 However, as only about half
of the patients in this study were reported to have a rash, the tendency to
focus on overt physical signs may be inappropriate. General practitioners who
suspect meningococcal infection should not be deterred from starting antibiotic
treatment,11 particularly when there are early
signs and symptoms of septic shock such as excessive tachycardia.
Interference with hospital tests and fear of rendering
cultures sterile is misguided if the consequence of delayed treatment is
death.13 Treating a potentially fatal condition
is more important than eliciting a precise diagnosis. Importantly,
species-specific polymerase chain reaction (PCR) testing is now available and is
a powerful diagnostic tool that is more sensitive than culture and less affected
by antibiotics. PCR tests may prove positive three days after initiating
treatment.4
General practitioners cannot assume that patients will be
treated quickly once admitted to hospital. Patients suspected of having
meningococcal disease may wait some considerable time in hospital before
treatment is started.14 Since parenteral
antibiotics interrupt growth of meningococci, and the build up of endotoxins and
cytokines in the plasma, the management of meningococcal disease cases is time
critical. How quickly treatment is initiated is the key issue, not who initiates
it.
The fear of administering inappropriate antibiotics should
not discourage pre-hospital treatment. Minimal harm can be expected if an
antibiotic is given and meningococcal disease is not
confirmed.13 It has been recommended in New
Zealand that any patient with a known allergy to penicillin is urgently
transferred to hospital without antibiotics.15
However, it is known that only a minority of those with a history of penicillin
allergy are subsequently confirmed as genuinely
allergic.16
Finally, despite the use of pre-hospital antibiotic
treatment in meningococcal disease being
questioned,17 it is generally agreed that
meningococcal infection should be treated with parenteral antibiotics as soon as
is possible.10 The current consensus is that it
is the most effective way of controlling life-threatening infection from
meningococcal disease.18 A reduction in case
fatality rates from the administration of pre-hospital antibiotics has been
observed in New Zealand3 and
elsewhere.1,2,13
There are a number of limitations to this study. First,
information regarding preliminary diagnosis, as assessed by the attending GP,
was unavailable. Second, some of the case notes were incomplete, which hindered
determination of the estimated distance of general practice from hospital.
Third, clinical condition of the patient at presentation was a potential
confounding factor. We could not exclude the possibility that cases who
presented to a GP with a rash were already well advanced in their illness and
were therefore more likely to receive antibiotics before being transferred to
hospital. Finally, differences by ethnicity, for example, may have remained
undetected due to small numbers. Similarly, some cases in this study died, but
we did not analyse outcome data because numbers were too small to make unbiased
comment. A prospective study that is large enough to stratify by known
confounders, and have adequate explanatory power to compare risk factors and
outcome data, is needed.
It is with great hope that we look to mass immunisation to
terminate the current and prolonged serogroup B epidemic in New Zealand. In the
interim, early and aggressive treatment of suspected cases of meningococcal
disease by GPs in the community setting is essential. A higher index of
suspicion and lower threshold for treatment are needed. Further effort to
encourage early diagnosis and treatment is necessary.
Author information:
Tania Riddell, Public Health Registrar; Chris Bullen, Public Health Physician,
Auckland Regional Public Health Service, Auckland
Acknowledgements:
This study was funded by the Auckland Regional Public Health Service, Auckland
District Health Board. Phillip Hill assisted with the original concept of the
study and its design.
Correspondence: Dr
Tania Riddell, P O Box 147 094, Ponsonby, Auckland. Fax: (09) 376 3238; email:
taniar@nhf.org.nz
References:
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