How to Reduce Ineffective Meningitis
They are three membranes which surrounds brain and spinal cord, which from the outside inwards are the dura mater, the arachnoid mater and the pia mater. Between the middle membrane and the inner membrane, in the subarachnoid space, is found the cerebrospinal fluid (CSF).
This fluid circulates from the ventricles via communicating apertures passing through the subarachnoid space, after which it flows over the surface of the brain and the spinal cord. Infective meningitis is a condition which is associated with inflammation of the arachnoid and pia mater with the presence of bacteria, viruses, fungi or protozoa in the CSF.
Meningitis is one of the most emotive of infectious diseases, and for good reason: even today, infective meningitis is associated with significant mortality and risk of serious sequelae in survivors.
Causes Of Inffective Meningitis
In the UK, more than 1500 cases of meningitis are notified annually. The most common cause of meningitis is recorded as viruses, and are often less serious than bacterial or fungal forms of the disease.
Bacterial meningitis is seen in all age groups, it majorly seen in young children, with 40–50% of all cases occurring in the first 4 years of life. They are two bacterias, N. meningitidis and S. pneumoniae which account for about 75% of cases. However, the pattern of micro-organisms causing meningitis is related to the age of the patient and the presence of underlying disease.
Human enteroviruses such as echoviruses and Coxsackie viruses account for about 70% of cases of viral meningitis in the UK. Herpes virus as well as varicella zoster viruses account for most other cases.
Candida species are rare cause of shunt-associated meningitis. Cryptococcus neoformans is regarded as an important cause of meningitis in patients with late-stage HIV infection and other severe defects of T-cell function.
Signs And Symptoms Of Inffective Meningitis
- Acute bacterial meningitis the patient suffers from sudden-onset headache, neck stiffness, photophobia, fever and vomiting.
On examination, Kernig’s sign may be positive. This is resistance to extension of the leg when the hip is flexed, due to meningeal irritation in the lumbar area.
- If the patient suffers from septicaemia with meningitis, there may be septic shock.
- The presence of a haemorrhagic skin rash is highly suggestive, but not pathognomonic, of meningococcal infection.
Patients not treated with bacterial meningitis deteriorate rapidly, with development of seizures, focal cerebral signs and cranial nerve palsies.
- In infants with meningitis, the early appearance of signs are usually nonspecific which include fever, diarrhoea, lethargy, feeding difficulties and respiratory distress.
- Focal signs of the disorder such as seizures or a bulging fontanelle occur at a late stage.
- Viral meningitis usually presents with acute onset of low grade fever, headache, photophobia and neck stiffness.
The most common diagnosis of meningitis is done by detection of the causative organism and/or demonstration of biochemical changes and a response of cells in Cerebrospinal Fluid.
CSF is collected with help of lumbar puncture, where a needle is inserted between the posterior space of the third and fourth lumbar vertebrae into the subarachnoid space. Before performing this procedure, the possibility of precipitating or aggravating existing brain herniation in patients with intracranial hypertension must be considered.
A CT scan must be performed before undertaking this procedure of lumbar puncture if any neurological abnormalities are present.
Acute bacterial meningitis is an emergency condition that requires urgent administration of antibiotics. In other forms of meningitis they may be use of adjunctive therapy such as steroids, and the administration of antibiotics to prevent secondary cases.
Empirical antimicrobial therapy have to be prescribed before the identity of the causative organism or its antibiotic sensitivities are known. The epidemiological features of the case, together with microscopic examination of the CSF is considered which is often helpful in identifying the likely pathogen.
Selection of empiric antimicrobial therapy, depends upon the four categories:
- Neonates and infants aged below 3 months;
- Immunocompetent older infants, children and adults;
- Immunocompromised patients; and
- Those with ventricular shunts.
Prevention of person-to-person transmission
- Patients with meningitis may be infectious to others.
- Neonates with meningitis usually have generalised infections, and the causative organisms can often be isolated from body fluids and faeces.
- Babies with meningitis should therefore be isolated to prevent infection spreading to other patients.
- Patients with meningococcal or Hib meningitis should be isolated until after at least 48h of antibiotic therapy.
- Contacts of these patients may be asymptomatic carriers and potentially infectious to others and/or at risk of developing invasive infection themselves.
- Chemoprophylaxis and vaccination can reduce these risks (see earlier).
- Patients with most other types of meningitis do not represent a significant infectious hazard, and enhanced infection control precautions are not usually necessary