bacterial meningitis


Also found in: Dictionary, Thesaurus, Encyclopedia.
Related to bacterial meningitis: Viral meningitis

meningitis

 [men″in-ji´tis] (pl. meningi´tides)
inflammation of the meninges, usually by either a bacterium (bacterial m.) or a virus (viral m.). When it affects the dura mater it is termed pachymeningitis; when the arachnoid and pia mater are involved, it is called leptomeningitis. The term meningitis does not refer to a specific disease entity but rather to the pathologic condition of inflammation of the tissues of the meninges. The etiologic agent can be anything that activates an inflammatory response, including both pathogenic and nonpathogenic organisms, such as bacteria, viruses, and fungi; chemical toxins such as lead and arsenic; contrast media used in myelography; and metastatic malignant cells. Enteroviruses are the most common causes of aseptic meningitis.
Bacterial Meningitis. This form occurs when pathogenic bacteria enter the subarachnoid space and cause a pyogenic inflammatory response. The most common causes are Streptococcus pneumoniae (pneumococcus), Neisseria meningitidis (meningococcus), and Haemophilus influenzae, which are responsible for approximately 70 per cent of all cases. The incidence is age-related. In adults, S. pneumoniae and N. meningitidis cause most of the cases; in children aged 1 month to 15 years, N. meningitidis and H. influenzae predominate; in neonates less than 1 month old, the disease is usually a nosocomial infection with gram-negative enteric bacilli.

Almost all bacterial infections of the meninges enter the nervous system after having invaded and infected another region of the body and then are spread by local extension, as from the sinuses, or through the blood, as in septicemia. The organisms gain access to the ventriculosubarachnoid spaces and the cerebrospinal fluid where they cause irritation of the tissues bathed by the fluid.

Bacterial meningitis typically begins with headache, nausea and vomiting, stiff neck (nuchal rigidity), and chills and fever. Irritability and confusion occur early in the course of the disease, and convulsive seizures occur in about 25 per cent of patients. As the disease progresses the patient becomes less rational, has decreasing levels of consciousness, and lapses into coma. Inability to straighten the knee when the hip is flexed (a positive kernig's sign) and involuntary flexing of the hip and knee when the neck is flexed forward (a positive brudzinski's sign) are indicative of meningeal irritation.

A diagnosis of bacterial meningitis is verified by isolation of the organism from a specimen of cerebrospinal fluid obtained by lumbar puncture. Treatment with the appropriate antibacterial agent is begun at once to reduce the numbers of proliferating bacteria attacking the central nervous system. Supportive measures include rest, maintenance of fluid and electrolyte balance, and prevention or control of convulsions with anticonvulsant drugs.

The prognosis is generally good, especially for meningococcal meningitis in which residual neurologic deficits and persistent convulsive seizures are rare. Pneumococcal meningitis and meningitis due to Haemophilus influenzae are more likely to be complicated by these sequelae as well as by septic shock and hydrocephalus.
Benign Viral Meningitis. This term encompasses a group of disorders in which there is some meningeal irritation but no pyogenic organism can be found in the cerebrospinal fluid. It is, therefore, called also aseptic meningitis complex, which is somewhat misleading because the meningeal irritation often follows infection with the mumps virus or with one of the picornaviruses.

The patient with this disorder typically complains of headache and signs characteristic of meningeal irritation, intolerance to light, and pain when the eyes are moved from side to side. Most of the symptoms are mild, and treatment is largely supportive and symptomatic; the disease is self-limiting.
Patient Care. Assessment of the patient with meningitis includes monitoring vital signs, neurologic status, and fluid and electrolyte status. The plan of care should include provisions for rest and relief from discomfort, a quiet and nonstimulating environment, protection from injury during convulsions, control of elevated body temperature, and isolation precautions as indicated by the specific causative organism. In general, enteric precautions are indicated for patients with aseptic meningitis caused by an enterovirus. Fungal and meningococcal meningitis require respiratory precautions. Antibiotics must be given precisely as ordered so as to avoid further damage to the central nervous system. Early signs of increased intracranial pressure from brain edema are reported promptly so that measures to reduce pressure can be taken as soon as possible. During the acute phase and convalescence the patient is watched for signs of complications such as septic shock, vascular collapse, and hydrocephalus. Nutritional status must be maintained throughout the course of illness to reinforce the patient's natural resources for combating infection and recovering from its deleterious effects.
Portals of entry resulting in meningitis, meningoencephalitis, and intracranial mass lesions. From Mahon and Manuselis, 2000.
aseptic meningitis any of several mild types of meningitis, most of which are caused by viruses; see viral meningitis.
bacterial meningitis meningitis caused by bacteria; common pathogens are Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, and Mycobacterium tuberculosis. Some types may be serious, acute, or even fulminating. See also viral meningitis.
cerebrospinal meningitis an inflammation of the brain and spinal cord; it may be caused by any of numerous different organisms.
epidemic cerebrospinal meningitis an acute infectious disease with seropurulent inflammation of the membranes of the brain and spinal cord, due to infection by Neisseria meningitidis (meningococcus). It usually occurs in epidemics, and symptoms are those of acute cerebral and spinal meningitis. There is also usually an eruption of erythematous, herpetic, or hemorrhagic spots on the skin. The fulminating or malignant form is known as Waterhouse-Friderichsen syndrome.
spinal meningitis inflammation of the meninges of the spinal cord.
viral meningitis meningitis due to any of various viruses, such as a coxsackievirus or the mumps virus, with lymphocytes in the cerebrospinal fluid. It usually has a short uncomplicated course characterized by malaise, fever, headache, stiffness of neck and back, and nausea. See also aseptic meningitis.

bacterial meningitis

Meningeal inflammation caused by bacteria which, if untreated, is often fatal, or associated with significant sequelae.
 
Epidemiology
60% are community acquired (C), 40% nosocomial (N); predisposing factors:
• Recent neurosurgery/use of neurosurgical devices—60% N;
• Immune dysfunction—20.5% N, 7.5% C;
• CSF leak—8.6% N, 3% C;
• Head injury—8.6% N, 3.5% C;
• Acute or chronic otitis media—< 1% N, 10% C;
• Others—Sinusitis, pneumonia, endocarditis, diabetes, alcoholism.

Microbiology
Haemophilus influenzae > Streptococcus pneumoniae > Neisseria meningitidis.

Management
Antibiotics and dexamethasone.

Mortality
± 25%; highest in those > age 60, obtunded at presentation or with seizures in past 24 hours.

bacterial meningitis

Acute bacterial meningitis Neurology Meningeal inflammation caused by bacteria which, if untreated, is often fatal, or associated with significant sequelae Epidemiology 60% are community-acquired–CM, 40% nosocomial–NM Predisposing factors Recent neurosurgery/use of neurosurgical devices–60% NM, immune dysfunction–20.5% NM; 7.5% CM, CSF leak–8.6% NM, 3% CM, head injury–8.6% NM, 3.5% CM,–acute or chronic otitis media–< 1% NM, 10% CM, sinusitis, pneumonia, endocarditis, DM, alcoholism Clinical Fever–95% at presentation, nuchal rigidity–88% at presentation, neurologic signs—confusion, lethargy, seizures, papilledema Microbiology H influenzae > S pneumoniae > N meningitidis Management Antibiotics and dexamethasone Mortality ± 25%, highest in those > age 60, obtunded at presentation, or with seizures in past 24 hrs

bacterial meningitis

See MENINGITIS.

Patient discussion about bacterial meningitis

Q. i have been in contact with someone whose in contact with bacterial meningitis. is this dangerous?

A. bacterial meningitis is one of the most lethal infections known. when people get infected by it they get a __ load of antibiotics and so are their families. but it all depends on what stage you had contact, and how close contact. in any way- he is probably under treatment now, no? if so, contact the doctors where he is hospitalized and ask them what is the protocol.

Q. What Causes Meningitis? I was told that meningitis is a very infectious disese. What causes meningitis?

A. Most cases of meningitis are caused by microorganisms, such as viruses, bacteria, fungi, or parasites, that spread into the blood and into the cerebrospinal fluid (CSF). Non-infectious causes include cancers, certain drugs and more. The most common cause of meningitis is viral, that is usually less severe. Bacterial meningitis is the second most frequent type and can be serious and life-threatening. Bacterial meningitis is a medical emergency.

More discussions about bacterial meningitis
References in periodicals archive ?
Emily Hannah King with her daughter Marina who has recovered from bacterial meningitis
Pathophysiology of Bacterial Meningitis: Mechanism(s) of Neuronal Injury.
The vaccines available protect against the three major causes of bacterial meningitis, meningococcal disease, pneumococcal meningitis and Haemophilus Influenzae Type b.
Apart from that, adults who were prone to overconsumption of alcohol, sustained head injury or had pneumococcal pneumonia were also more susceptible to bacterial meningitis.
We analyzed outcomes of 175 children admitted with diagnosis of acute bacterial meningitis. Of 175 children 102 (58%) were males and 73 (42%) were females.
Acute bacterial meningitis has high mortality and morbidity despite widespread availability of antimicrobial and adjunctive therapy, due to its atypical presentation and failure to be recognized early.
About the affects she said that although we often think of meningitis as being a particular risk to the very young, children only account for 55 per cent of cases and both viral and bacterial meningitis can occur at any age.About the viral meningitis, Dr.Salma Shaikh said that viral meningitis tends to appear in winter epidemics and is usually less severe and most of the people recover fully, often without specific treatment.
Typical CSF findings for bacterial meningitis are an elevated white blood cell count (WCC), with polymorph predominance, decreased glucose and increased protein.
The comments from the Meningitis Research Foundation (MRF) come after a new study found that classic symptoms of bacterial meningitis were uncommon among babies with the deadly illness.
The mortality rate among patients with bacterial meningitis and the frequency of neurological sequelae among those who survive are high, despite major progress in intensive care and effective antimicrobial chemotherapy.