Following a myocardial infarction, major illness, surgery or trauma the concentration of serum cholesterol, triglycerides and HDL-cholesterol change significantly and cannot be used for diagnosis of lipid disorders. Serum cholesterol and HDL will drop significantly, whereas levels of serum triglycerides increase and will remain elevated for several weeks.

The concentrations of cholesterol, triglycerides and HDL do not change significantly within the first 24 hours after a major event and can be measured during this time. If this is not done lipids can be measured 3 months after a major event when they have returned to equilibrium.

A steady decrease in the susceptibility of N. meningitidis to penicillin has been seen over the last five years, both in Australia and overseas. As yet, true resistance has not been a problem, however, approximately 75% of invasive isolates are considered "less sensitive" (MIC 0.06 – 0.5 mg/L) to penicillin. Penicillin, in appropriate doses, remains effective for the treatment of disease due to these "less sensitive" strains.

The hallmarks of meningococcal disease are fever and a petechial rash. The development of vomiting and drowsiness is suggestive of meningitis. Early in the disease, a less distinctive maculopapular rash may develop that appears more typical of a viral infection. The major problems with early diagnosis of the disease are the nonspecific symptoms and signs and, in sporadic cases, the lack of community and medical awareness. The glass test, used to demonstrate non-blanching petechia, is promoted for parents in England but not in Australia.

Depending on the clinical circumstance, the specimens suitable for microbiological confirmation of meningococcal disease include blood, cerebrospinal fluid (CSF), synovial fluid, skin lesion aspirate, and throat swab. Blood cultures are positive in about 50% of cases overall but are more likely to be positive in meningococcaemia compared to meningitis. In about half of patients with systemic disease, meningococci can be isolated from a throat swab with a 97% phenotypic correlation to the invasive isolate. In up to two thirds of cases with a petechial rash, either the microscopy or culture of a skin lesion aspirate will be positive. Some laboratories also offer latex particle agglutination (LPA) testing for blood and CSF, however, this is not performed at PathCentre due to problems of sensitivity and specificity. Gram stain microscopy of CSF and other sterile sites demonstrating Gram negative diplococci can give a presumptive diagnosis.

The current NH&MRC guidelines for the control of meningococcal disease recommend that either parenteral penicillin or a third generation cephalosporin be administered prior to referral to hospital for suspected cases. Although this has been reported to improve the clinical outcome, it will reduce the frequency of positive cultures, particularly from blood. One study demonstrated a reduction in isolation rate from 50% to 5%. Cerebrospinal fluid and skin aspirates are likely to remain culture positive for longer, and a throat swab culture will be unaffected by penicillin therapy. The NH&MRC guidelines state that throat swabs should be reserved for outbreak situations in patients with suspected meningococcal disease, especially if they have received prior antibiotics. The role of lumbar puncture in meningococcal disease has been debated for some time. Although sensitive (89-94%) in meningitis cases, the main concern is the rare occurrence of brainstem herniation due to raised intracranial pressure. In addition, there is a high frequency of negative CSF findings (8%) early in meningococcal meningitis which may mislead clinicians into withholding antibiotics prior to culture results.

The trend to preadmission administration of antibiotics, together with an increasing reluctance to perform lumbar punctures, will reduce the number of culture proven cases and increase the proportion of presumptive cases. Polymerase chain reaction (PCR) of meningococcal DNA is a sensitive and specific method for diagnosis that can be performed on EDTA blood, CSF, and specimens from other sterile sites. PathCentre has introduced a diagnostic PCR for meningococcal disease. PCR screening in England and Wales has shown this technique to be very sensitive and specific. Recommendations for the use of PCR are shown in the Table. Complementary to the diagnostic PCR, PathCentre is also developing a PCR system for serogroup confirmation from meningococcal cases without a positive culture. This distinction is important due to the availability of a polysaccharide vaccine against serogroup C, but not serogroup B. This vaccine can be used in the control of serogroup C meningococcal outbreaks. A more efficacious conjugate serogroup C vaccine able may be available in Australia soon. This will make case ascertainment and serogroup information of greater importance in the future.

TABLE. Recommendations for the use of diagnostic PCR for meningococcal disease.

• Cases of bacterial meningitis when lumbar puncture is not performed
• Cases of suspected bacterial meningitis or meningococcaemia when antibiotics are given prior to presentation
• Cases of suspected bacterial meningitis with a negative CSF culture
• Autopsy cases when the cause of death is suspected to be bacterial meningitis or meningococcaemia

For further information contact Dr David Speers, Clinical Microbiologist, PathCentre on (08) 9346 3122.

A Multi-Disciplinary Thyroid Clinic has been established at the Sir Charles Gairdner Hospital. This clinic will expedite the investigation and management of patients with thyroid disease, with a special emphasis on thyroid nodules and cancers. The clinic has the services of SCGH surgeons, endocrinologists, nuclear medicine physicians, radiologists and PathCentre pathologists who are available for consultation on the day of the clinic.

Patients may be booked into the clinic by telephoning 9346 3632 at SCGH or by sending a SCGH referral form for an outpatients appointment and specifying the ‘Multi-Disciplinary Thyroid Clinic’. Patients will be seen by an endocrine surgeon or endocrinologist, who will decide on the need for further testing, which will generally be done the same day. Test results will be included in the letter of reply to referring practitioners.

Services provided by PathCentre pathologists will include immediate reporting of direct or image-guided fine needle aspiration (FNA) of thyroid lesions, and rapid routine thyroid function testing.

FNA of palpable thyroid lesions and thyroid function testing will remain available to individual practitioners through the usual direct referral to PathCentre.

Our efforts in changing PathCentre into a modern laboratory system in place of our three separate predecessors has been recognised in the Premier’s Awards for excellence in management. We gained the distinction of being "Highly Commended", ahead of the many other entrants and finalists in the category of "Change Management". Everyone at PathCentre is proud of this achievement which acknowledges the endeavours of our entire staff.