Diagnosis and treatment of meningitis in children

Catherine McCabe looks at current developments in the improved diagnosis and treatment of children with meningococcal meningitis

Catherine McCabe looks at current developments in the improved diagnosis and treatment of children with meningococcal meningitis Ireland has experienced an increase in the most common form of meningitis infection every year since 1994. While the number of deaths from meningitis is decreasing all the time, Ireland has a higher rate of infection than other European countries.

Meningococcal meningitis is the most common type of meningitis in all age groups. It is most prevalent in children under five and in late adolescence.

Approximately 50% of children with meningococcal meningitis develop meningococcal septicaemia. This is known as meningococcal disease and when it occurs, the mortality rate rises from 10%-50%.1 

Clinical manifestations of meningococcal meningitis 3

The organism which causes the infection is neisseria meningitidis of which there are seven serogroups (A, B, C, W135, X, Y, 29E). Serogroups B and C are the most common with group B causing 58% of cases and group C causing 40% of cases in Ireland.

Meningococcal infection is endemic in Northern Europe, with a general rate of 2.5 cases per 100,000 of the population. However, it is considered to be hyperendemic in Ireland, due to consistently high rates of infection since 1994. In 1997, 243 cases were reported. This rose to 365 in 1998 and the upward trend is continuing in 1999.2 Improved diagnostic procedures and the establishment of a national meningococcal reference laboratory at the Childrens Hospital, Temple Street have resulted in definitive diagnosis, recording and monitoring of all cases of meningococcal infections in Ireland. This may explain why the number of cases appears to be rising.

Diagnosis

Diagnosis is based on a nursing and medical assessment of the child, and on laboratory investigations. The initial nursing assessment requires a detailed history from the parents or carer of the childs activities and illness in the previous 10 days, and a neurological assessment using the paediatric version of the Glasgow Coma Scale (GCS). 

Clinical manifestations vary with age. Children over two years may present with fever, vomiting, rash, photophobia, headache, neck rigidity, positive Brudzinskis and Kernigs sign. 

Children under two years present with vague symptoms such as anorexia, poor sucking or feeding, altered sleep pattern and irritability. Other more significant symptoms in this age group are fever, vomiting, rash, bulging fontanel and altered level of consciousness.3

A neurological assessment is conducted by the nurse using the GCS. This scale was originally designed as a tool for head-injured patients and has been criticised as inadequate as a neurological assessment tool for patients with meningitis.4 These patients may be drowsy but obey commands and have a GCS of 14, yet may be in the early stages of acute increased intracranial pressure. 

However, as it is currently the neurological assessment tool used by nurses in most hospitals in Ireland, and in order to ensure accuracy and consistency, the neurological assessment of a child should be conducted by the same nurse on a shift and always in the presence of one or both parents. Parents know their child best and can indicate to a nurse what is normal and abnormal behaviour. In addition, it is important that nursing staff be aware that children under 10 years of age are neurologically immature. This needs to be taken into account when interpreting and documenting the findings of a neurological assessment.5

The assessment and frequent monitoring of a childs cardiovascular status is essential for children with meningococcal disease as they decompensate very rapidly when bacteraemia and septic shock are present. Cardiovascular, respiratory and renal function need to be monitored continuously in order to prevent and manage multi-system failure.6

Laboratory diagnosis is made using culture and non-culture methods on samples of blood, cerebrospinal fluid and from skin scrapings. Since 1996 non-culture methods of diagnosis have been available at the meningococcal reference laboratory. Minute quantities of bacterial or viral DNA can now be detected in CSF or blood. 

Using polymerase chain reaction (PCR) a high number of these gene copies are generated. As a result a definitive diagnosis can be made within 24-48 hours regardless of previous antibiotic treatment.7

Treatment

Treatment commences prior to identification of the causative organism. If a GP suspects that a child has a meningococcal infection, benzylpenicillin should be administered immediately. Following admission, ampicillin and cefotaxime are the drug of choice for children under three months. Penicillin and cefotaxime are given to children over three months of age. If the child is known to be allergic to these drugs, chloramphenicol can be used. These children are also given rifampicin which is also given prophylactically to known contacts to eradicate nasal and respiratory tract carriage of the causative organism.3

Maintaining cardiovascular function will require fluid replacement, volume expanders (Albumin) and INOtropic support with continuous assessment and re-assessment. Elective intubation and ventilation can be used routinely to support respiratory function although not all consultants will do this unless respiratory function is compromised.

Renal function should be maintained at an output of 0.5-2ml/kg/hr (depending on the childs age and hydration status). Dexamethasone is a controversial treatment and is not used by all consultants to treat children with meningococcal disease. However, one study has found it to be useful in reducing cerebral irritation.8

Irish study

A small (n = 12) Irish study found that in addition to conventional therapies, treatment using continuous veno-venous haemofiltration in conjunction with protein C supplements and heparin is successful in reducing mortality and morbidity rates in people with meningococcal disease. Continuous veno-venous haemofiltration is effective in removing proinflammatory cytokines, maintaining fluid balance and temperature regulation. 

Protein C is a natural anticoagulant and anti-inflammatory agent and normal levels seem to be greatly reduced in people with meningococcal disease. Protein C concentrate is now available in Ireland through the Blood Transfusion Service Board. Treatment with protein C should commence within four hours of admission using a recommended protocol.

Heparin was also used in this study and is recommended for patients with a rash, disseminated intravascular coagulation (DIC) or gangrene. If this treatment is unsuitable due to hypofibrINOgenaemia and thrombocytopenia secondary to DIC, then fresh frozen plasma and platelet transfusions are necessary. This study did not compare the findings with patients with meningococcal disease who did not receive this treatment. However, it recommends a double-blind, randomised, controlled multi-centre trial to confirm these results.

Prevention

Chemprophylaxis should be


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