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Nursing Case Study Bacterial Meningitis


Case 1

A six month old male presents to the emergency department with a history of lethargy. He was seen 3 days ago with fever and URI symptoms, diagnosed with otitis media and treated with oral amoxicillin. This morning he had become irritable and was less active than usual. He has vomited three times and his urine output is noticeably decreased. He has no diarrhea.

Exam: VS T 40.0, P 90, R 30 (irregular), BP 120/90, weight 8kg. He is lethargic and arousable only to painful stimuli. His anterior fontanel is full and tense, and he has questionable neck rigidity. His TMs are red and bulging. His pupils are reactive, but his eyes do not focus well on his parents. His heart, lungs and abdomen are normal. His color and perfusion are good. He has no petechiae. He moves all his extremities weakly and his DTRs are hyperactive.

A CBC, blood culture and chemistry panel are drawn. An IV is started. Since an increased ICP (intracranial pressure) is suspected, a lumbar puncture (LP) is initially delayed and he is immediately given 500 mg of ceftriaxone IV. A stat CT scan of the brain is normal, so an LP is done and the CSF (cerebrospinal fluid) is visibly hazy. An infectious disease consultant is called to inquire about IV dexamethasone and vancomycin. Both are recommended and given. The CSF results return 1 hour later showing 450 WBCs, 95% segs, 5% monos, total protein 75, glucose 25 mg/dl. Gram stain of the CSF shows many WBCs with few gram positive cocci. He is admitted to the pediatric ICU.


The clinical presentation of this patient, with a very rapidly evolving febrile illness, changes in sensorium and evidence of increased intracranial pressure, is very compatible with a diagnosis of CNS (central nervous system) infection. Bacterial meningitis occurs more frequently between the ages of 2 months and two years. Acquisition of infected aerosolized particles, with initial colonization of the nasopharynx, is followed by subsequent replication in the regional lymph nodes, invasion, septicemia and CNS infection. The lack of anticapsular antibodies increases the risk of invasion. Rarely, the infection is due to spread from a contiguous focus such as the sinuses, the middle ear, or the mastoids. Bacterial meningitis secondary to otitis media is an uncommon phenomenon, but when it does occur, it is usually septicemic in origin, rather than due to direct extension.

Manifestations of bacterial meningitis are variable and depend upon the child's age and the duration of illness. In young infants, evidence of meningeal inflammation may be minimal and only irritability and poor feeding may be present. Body movements of infants with meningitis result in pain, accordingly a strong suspicion of CNS infection is aroused when the child does not wish to be handled but prefers to remain motionless. Such paradoxical irritability (which worsens when the child is carried, rocked or gently bounced), is highly suggestive of meningitis.

The older child will present with more clinical findings, such as nuchal rigidity, vomiting, lethargy and photophobia. Most cases of meningitis will be either of bacterial or viral etiology. Common bacterial causes in this age group include Streptococcus pneumonia (pneumococcus) and Neisseria meningitidis (meningococcus). The advent of a very efficacious vaccine against H. influenzae type B, has resulted in an almost complete disappearance of meningitis due to this etiological agent. Prior to this vaccine, this was the most common cause of bacterial meningitis.

An LP is indicated in patients with clinical findings compatible with meningitis. Strong consideration should be given to delaying the LP in patients with clinical findings of increased intracranial pressure. However, antibiotic administration should not be delayed by this. Antibiotics must still be given immediately once bacterial meningitis is suspected. The patient in our case has evidence of increased intracranial pressure since he has decreased sensorium, a bulging tense fontanel, hyperactive reflexes and changes in the vital signs such as a decreased pulse rate, hypertension and irregular respirations (Cushing's triad). Accordingly, caution should be taken before performing the LP due to the possibility of precipitating herniation. A CT scan of the head is a very rapid and accurate means to confirm increased intracranial pressure and if present, measures such as the administration of mannitol and hyperventilation, after rapid sequence intubation, should be instituted before the LP is done. Analysis of the CSF is usually very useful in confirming the diagnosis of bacterial meningitis. Acute bacterial meningitis is characterized by an elevated CSF white count with a predominance of polymorphonuclear cells (neutrophils), a decreased CSF glucose level, an increased protein value and a positive gram strain and culture. Administration of oral antibiotics prior to the LP, do not greatly modify the LP results, except for a slight decrease in the rate of identifying the organism on gram strain and cultures.

The treatment of meningitis is directed at reducing the damage produced by the inflammatory response by maintaining adequate cerebral perfusion with the use of adequate amounts of intravenous fluids and agents that reduce intracranial pressure and by treating the infection. The use of a third generation cephalosporin such as cefotaxime (50 mg/kg dose every 6 hours) or ceftriaxone (100 mg/kg day in one dose) provides coverage for most of the agents responsible (pneumococcus, meningococcus, H. influenzae type B) for meningitis except for penicillin-resistant pneumococcus which require the addition of vancomycin. Antibiotics used to treat meningitis must reliably penetrate the blood brain barrier in addition to reliably cover the organisms involved. The duration of treatment is dictated mostly by the clinical course but usually is 5 to 7 days for meningococcal infections and 10 days for infections due to pneumococcus. Neonatal meningitis has a different group of etiologic bacteria and antibiotics which are covered in the chapter on neonatal sepsis.

The survival of patients with bacterial meningitis has improved but it still remains a disease with high morbidity. Approximately half of those with S. pneumoniae and 15 percent of those with H. influenzae meningitis will develop neurological sequela. Cerebral infarction occurs in 5 to 20 percent of the patients as a result of localized inadequate perfusion due to local thrombosis, arteriolar vasculitis and phlebitis secondary to the inflammatory response. Sensorineural hearing loss is the most common sequela occurring in approximately 15 percent of cases. The hearing loss is usually severe, bilateral and permanent, and it occurs during the first few days of the infection. Penetration of bacteria through the internal auditory canal results in inflammation and destruction of the auditory nerve. Reduction in the incidence of hearing loss was reported with the use of corticosteroids (dexamethasone) for cases of H. influenzae meningitis, but proof supporting the benefit of corticosteroids with other causes of bacterial meningitis is not as evident. The use of corticosteroids is currently controversial due to the decrease in cases of H. influenzae meningitis (due to routine H. influenzae vaccine) and the fact that most cases of bacterial meningitis are now caused by pneumococcus and meningococcus, for which the benefit of corticosteroids is less proven.

Primary prevention of meningitis is accomplished by the administration of H. influenzae type B and S. pneumoniae vaccines to infants. Meningococcal vaccine is also available, but it is not routinely recommended, except adolescents and adults residing in dormitories or military barracks. Secondary prevention, with antibiotics such as rifampin is recommended for close contacts of patients with invasive H. influenzae type B and N. meningitis disease (but not for pneumococcal meningitis).


Case 2

A three year old female presents to the emergency department with a two day history of headache, nausea, vomiting and fever. She was seen by a physician two days ago who diagnosed otitis media and prescribed amoxicillin. She has taken six doses. Her immunizations are up to date. She is conscious, alert and complains of pain over the neck area. On examination she has pain on flexion of the neck. An LP showed 453 WBCs with 75% neutrophils and a glucose of 50 mg% (blood glucose 90 mg%) and a protein value of 55 mg%. A gram strain is negative for bacteria. Her headache improves and she appears less ill following the LP. She is admitted to the hospital with the diagnosis of viral meningitis. A repeat LP done 20 hours after the initial LP, shows 315 WBCs with 83% lymphocytes and a glucose value of 75 mg%, blood glucose of 89 mg%, and protein of 30 mg%. She is largely asymptomatic following the second LP. CSF cultures remain negative. A CSF PCR for enterovirus is positive.


Aseptic meningitis is characterized by lymphocytic/monocytic predominance of the CSF differential. The CSF protein is not as high and the glucose is not as low, compared to bacterial meningitis. Aseptic meningitis is almost always due to viral etiologies; however the rare case of tuberculous and fungal meningitis will present as an aseptic meningitis as well. Patients with viral meningitis can have all of the signs and symptoms of patients with bacterial meningitis; however, their findings are less severe. The classic patient with bacterial meningitis is toxic in appearance, irritable, and/or lethargic, possibly with other signs of sepsis. The typical patient with viral meningitis is alert and cooperative, but uncomfortable and mildly ill. Young infants are the most difficult to assess. Older cooperative children who can speak and express their symptoms are easier to evaluate. A lumbar puncture has two advantages in cases of viral meningitis in that it will usually ascertain a firm diagnosis and it will usually provide some degree of headache relief.

CSF neutrophil predominance can be initially seen in up to two thirds of cases of meningitis due to enterovirus and a slight decrease in the CSF blood glucose ratio occurs in one fourth of pediatric enteroviral meningitis. The low protein value and the relative low WBC are also indicative of a viral etiology. Enteroviruses are the leading cause of aseptic meningitis and account for 90 percent of all cases in which a pathogen is identified. Infants and children are most commonly affected and the prognosis is generally excellent. A CSF PCR for enterovirus is highly accurate in making an etiological diagnosis and will be positive in the great majority of cases. The repeated LP done 12 to 24 hours after the first will show a rapid shift in the CSF differential count from neutrophils to mononuclear predominance.


Questions

1. A three year old male presents with a bad headache, nausea, photophobia and fever (temp 38 degrees). His immunizations are up to date. He is not toxic in appearance. He is alert and cooperative. He has mild photophobia and mild nuchal discomfort without rigidity. He can speak and ambulate normally. The remainder of his exam is unremarkable. If this patient has meningitis, does he/she have bacterial or viral meningitis? What factors suggest one or the other?

2. An LP is done on the patient in question #1. The results show the following: 3 RBCs, 200 WBCs, 70% segs, 10% lymphs, 20 % monos, total protein 45, glucose 50. Gram stain of the CSF shows many WBCs and no organisms seen. Is this CSF analysis consistent with bacterial or viral meningitis? Which factors suggest one or the other?

3. What are the three most common bacteria that cause meningitis and what antibiotic covers them with close to 100% certainty?

4. Match the CSF results with the diagnosis (normal CSF, viral meningitis, bacterial meningitis). Validate your answer. Assume that the patient is 6 months old.


References

Dodge PR. Neurological Sequela of acute bacterial meningitis. Pediatr Ann 1994;23:101-106.

Wubbel L, McCracken CH. Management of bacterial meningitis. Pediatr in Rev 1998;19:78-84.

Schuchat A, Robinson K, Wengor JD, et al. Bacterial meningitis in the United States, 1995. N Engl J Med 1997;337:970-976.

Feigin RD, Shackelford PG. Value of repeat lumbar puncture in the diagnosis of meningitis. N Engl J Med 1973;289:571-574.


Answers to questions

1. This is most likely a viral meningitis. He is older, so his risk of bacterial meningitis is lower. He has been fully immunized, which presumably means that he has had H. influenzae, type B vaccine. He has probably had pneumococcal vaccine, but this can't be automatically assumed. He is alert, ambulatory, and not toxic in appearance, which all suggest that he does not have an overwhelming infection such as bacterial meningitis.

2. This is most consistent with viral meningitis. Although he has a high percentage of segs, this is still consistent with early viral meningitis. Cases of bacterial meningitis which have not been pre-treated with antibiotics almost always have more than 90% segs. The gram stain does not show any organisms which makes bacterial meningitis less likely. This laboratory analysis of his CSF suggesting viral meningitis, is consistent with his clinical appearance which also suggests viral meningitis (see the answer to #1 above).

3. Pneumococcus, meningococcus and Haemophilus influenzae type B. Pneumococcus is usually sensitive to penicillins and cephalosporins, but some resistance has emerged so vancomycin should be given in addition to cefotaxime or ceftriaxone. Meningococcus is sensitive to penicillin so cefotaxime or ceftriaxone provides sufficient coverage. H. influenzae type B is sensitive to cefotaxime and ceftriaxone, but this organism is not a common cause of bacterial meningitis due to widespread immunization against this organism.

4. CSF 1 shows bacterial meningitis. The increased number of cells in the CSF with a predominant number of neutrophils makes this a strong likelihood possibility. In addition, he also has a very low glucose CSF level (CSF, blood glucose ratio of 25%) and an increased protein value sometimes. Cases of early viral meningitis can present with an increased number of cells and neutrophils but usually the CSF glucose is normal or not lower than 40% of the blood CSF value.

4. CSF 2 is normal. The normal number of WBCs in the CSF depends upon the age of the patient. The younger and more immature the infant is, the higher the value is. CSF glucose value depends upon the value of glucose in the blood and upon the integrity of the blood brain barrier. In patients with normal meninges the CSF value is usually about 75% of the blood level. When the meninges become inflamed, the active transport of glucose across the blood brain barrier becomes altered and the ratio drops proportionately to the degree of inflammation. Most viral meningitis produce less changes than bacterial meningitis accordingly CSF glucose values are lower in bacterial meningitis.

4. CSF 3 shows viral meningitis. Most cases of viral meningitis will present with a moderate increase in the number of white cells and a percentage of neutrophils not higher than 60-70%.

4. CSF 4 is inconclusive. The high percentage of neutrophils indicates that bacterial meningitis is possible. It would be wise to administer antibiotics until more information can be obtained. The gram stain result will be helpful. If it is positive for organisms, then this indicates bacterial meningitis. If the gram stain is negative, bacterial meningitis still cannot be totally ruled out. The child's clinical condition is not part of this table, but in reality, a child who is alert, active and playful is more likely to have viral meningitis, as opposed to a lethargic, toxic child who is more likely to have bacterial meningitis. This will probably turn out to be a case of viral meningitis despite the high percentage of neutrophils, since an early viral meningitis will often have high neutrophil percentages. A repeat LP 12 to 24 hours from the first LP will be helpful. A repeat LP which demonstrates a clear shift toward mononuclear cells, is consistent with viral meningitis, while no shift, or only a slight shift would suggest bacterial meningitis. Culture of the CSF will be most definitive if it is positive, but this result will not be available for at least 24 hours.






Case Study
D.F. is a 65-year-old male who has brain cancer. He is admitted to a private room in a community hospital for adjustment of anti-seizure medication and to receive chemotherapy. Within 48 hours of admission D.F. develops a rash and fever. Initially, the rash is considered a drug reaction to the anti-seizure medicine and the fever is considered a reaction to the chemotherapy. D.F. complains of a severe headache. An infectious disease physician evaluates him. The differential includes meningitis and tumor. A lumbar puncture is performed to obtain cerebrospinal fluid (CSF) for analysis. The CSF analysis shows elevated opening pressure, elevated protein, low glucose (hypoglycorrhachia), cloudy fluid and a positive Gram stain. Bacterial meningitis is the presumptive diagnosis. Broad-spectrum empiric antibiotic therapy is initiated.

Meningitis
Meningitis is an anxiety-provoking topic for many health care workers who often have common misperceptions about meningitis. These inaccuracies include that meningitis is always infectious; that the agents causing meningitis can be easily transmitted from person to person; that people diagnosed with meningitis are highly infectious; and that meningitis is always associated with severe complications (e.g., death). Nurses play an important role in providing accurate information to dispel these misperceptions and decrease fear and anxiety in patients, family, staff and the public.

Although some types of bacterial meningitis can be catastrophic, the reality is that meningitis is a complex group of diseases with varying severities and epidemiologies. The etiology of meningitis can be either infectious (bacteria or viral) or noninfectious (such as tumor, trauma, brain abscess, subdural empyema or pharmacologic reaction).

Since viral meningitis is often a self-limited disease, it is probably fair to assume that many cases of viral meningitis go undiagnosed and/or do not have a specific etiologic agent identified. The most common pathogens associated with meningitis are listed in Table 1.

A lumbar puncture is the usual procedure performed from which a diagnosis of bacterial vs. viral meningitis can be established. CSF obtained from the lumbar puncture is examined directly and cultured, and the results of these analyses are critical to diagnose either bacterial or viral meningitis. Table 2 summarizes the most common CSF findings associated with bacterial or viral meningitis. Severe complications can result from bacterial meningitis but are not very common from viral meningitis.

Bacterial Meningitis
Worldwide, bacterial meningitis is a common disease, with 75 percent-80 percent of all cases associated with three pathogens: Haemophilis influenzae, Neisseria meningitidis and Streptococcus pneumoniae. In the United States, as of the late 1990s-more than 10 years after licensure of the H. influenzae serotype b vaccine (Hib)-the most common agents are N. meningitidis and S. pneumoniae. During the early 1990s, approximately 25,000 cases occurred annually in the United States, with 70 percent identified among children age 5 or younger. Each year more than 2,000 deaths were attributed to bacterial meningitis.

The predominant organisms responsible for bacterial meningitis vary, depending on the age of the patient (see Table 3). Epidemics of bacterial meningitis do occur and are always associated with N. meningitidis.

Bacterial meningitis in adults is characterized by abrupt onset. Symptoms can include sudden fever, intense headache and meningismus. Signs of meningeal irritation associated with acute febrile illness or dehydration without actual infection of the meninges may be subtle or acute; may or may not be accompanied by Kernig’s sign (inability to extend the leg fully when in a sitting position or when the thigh is flexed upon the abdomen), or Brudzinski’s sign (flexion of the neck resulting in flexion of the hip and knee, or with passive flexion of the lower limb on one side a similar movement occurs on the opposite side). Other signs of cerebral dysfunction (confusion, delirium, declining level of consciousness) may be present. Constitution signs can include nausea, vomiting, rigors, myalgia, weakness and diaphoresis. Seizures occur in up to 40 percent of cases.

A petechial rash may develop in association with N. meningitidis meningitis. However, neonates with bacterial meningitis often do not manifest fever or meningismus-the clinical symptoms may be nonspecific (e.g., irritability, high-pitched crying, listlessness, refusal to feed). Elderly patients may have no fever and the main clinical symptoms may be lethargy/obtundation with variable signs of meningismus.

Bacterial meningitis is diagnosed by CSF examination. Typical findings are: elevated opening pressure, elevated protein and hypoglycorrhachia. The fluid appearance may be cloudy or turbid. The CSF leukocyte concentration is usually elevated with a neutrophilic pleocytosis. CSF Gram stain examination is associated with rapid and accurate organism identification in up to 90 percent of bacterial meningitis cases.

Emergent empirical broad spectrum antimicrobial therapy, based on age, underlying disease status and medical history, should be initiated as soon as a diagnosis of bacterial meningitis is likely even if no bacteria are visualized by Gram stain.

Upon identification of the bacterial pathogen, antimicrobial therapy can be modified based on susceptibility results. Therapy should be individualized and based on the patient’s clinical response. Neurologic sequelae (e.g., hearing loss, seizures and behavioral problems) are associated in about 33 percent -50 percent of bacterial meningitis survivors.

Infection control recommendations for patients with bacterial meningitis-with two important exceptions-are the practice of Standard Precautions, with strict attention to meticulous hand washing. The two exceptions are bacterial meningitis due to either N. meningitidis (meningococcal) or H. influenzae.

Infection Control Precautions
For meningitis caused by either of these two organisms, additional infection control strategies are indicated since transmission can occur by the droplet/close contact route-for up to 24 hours even after starting effective antibiotic therapy.

The Centers for Disease Control and Prevention (CDC) recommends droplet precautions in addition to Standard Precautions for bacterial meningitis caused by either N. meningitidis or H. influenzae. Precautions may be discontinued 24 hours after initiation of effective therapy. When droplet precautions are initiated, the risk for transmission is much lower. The local health department should be notified to arrange for follow-up of household and community contacts.

Meningococcal Meningitis
Because of the potential for an adverse outcome, concern and anxiety are common whenever a meningococcal infection (N. meningitidis) is suspected or diagnosed. The incubation period from exposure to the disease can be 2-10 days, but usually is 3-4 days.

Transmission is by droplet/direct contact with respiratory secretions or contact with laboratory cultures. It is not by aerosols, and thus the risk for transmission from casual or brief contact with infected patients is minimal. In a health care setting, spread of the infection is uncommon.

Health care workers at risk for transmission are those with intense direct contact, e.g., mouth-to-mouth resuscitation, intubation or nasotracheal suctioning without the use of protective barriers, or lab personnel who handle cultures without protection. Only these staff will require chemoprophylaxis.

General exposure guidelines for household contacts and child care contacts are at least 4 hours close contact during the week before the illness onset or mouth-to mouth kissing.

Postexposure chemoprophylaxis can be either rifampin, ciprofloxacin or ceftriaxone. Ciprofloxacin should not be administered to children or pregnant women. Rifampin turns urine, saliva and tears an orange color. Also, it has been associated with nausea, vomiting and rash.

To promote adequate absorption, rifampin should be taken on an empty stomach. Lab staff who have been exposed percutaneously require penicillin prophylaxis. Immunization of health care staff after chemoprophylaxis for sporadic exposure is not indicated.

Vaccine for High-Risk Groups
Meningococcal vaccine, although not routinely recommended, should be given to certain risk groups over 2 years of age-e.g., asplenic people-and is used as a control measure during community and college outbreaks. Additional risk groups susceptible to serious meningococcal infections include persons with terminal complement deficiencies and laboratory personnel who are routinely exposed to N. meningitidis in solutions that may be aerosolized.

Administration of meningococcal vaccine is not indicated for hematopoietic stem cell transplant (HSCT) recipients, but administration of the vaccine should be evaluated for HSCT recipients who live in endemic areas or are experiencing outbreaks.

Bacterial meningitis can be very serious; children are usually hospitalized. Most types of bacterial meningitis will not be spread person-to-person; for the types that can be spread, good hygiene, especially handwashing and environmental cleanliness, are important preventative measures.

Immediate contact with the local health department is very important for the management of bacterial meningitis. Responsibilities of the health department include communicating with the patient’s physician, making recommendations to prevent infection transmission and working with local health care workers and the community to reduce the risk for transmission.

In the school and child care setting, parents of exposed children should receive information about meningitis, recommendations for antibiotics and instructions about what to do if their child develops any symptoms of concern (such as fever, headache, rash) during the incubation period.

H. Ibfluenzae Meningitis
In health care settings, transmission of the bacteria H. influenzae from a patient with the infection is exceedingly rare. Because of widespread use of the Hib vaccine, people are usually not unduly anxious or concerned about this disease. Some people-such as those who live in the same household, attend the same day care or are members of the same classroom-may have more than brief or casual contact with the infected person.

General guidelines to identify persons who may have had more than brief or casual contact are those who were:

  • living with the infected person or had at least 4 hours of exposure to the infected person in the childcare setting or the classroom; or
  • attending the same child care as the infected person for 5-7 days before infection onset.

Rifampin is the agent of choice for chemoprophylaxis, but contraindications (e.g., pregnancy, liver disease, drug interactions) must be considered. Children who have H. influenzae should have their hearing tested after recovery.

Viral Meningitis
Viral meningitis (aseptic meningitis), although common in occurrence, is rarely life threatening. Viral meningitis is generally not a reportable disease (depending on whether a reportable etiologic agent-such as mumps-is identified). For this reason, the actual incidence of viral meningitis is not known. However, seasonal increases occur in late summer and early autumn and are mainly attributed to arbovirus and enterovirus activity.

Seasonal predilection occurs with lymphocytic choriomeningitis virus (fall and winter) and mumps (winter and spring). Identification of the viral agent is challenging-under ideal circumstances, serologic and virology isolation methodology may yield a specific etiologic agent identification for about half of the cases diagnosed.

Viral meningitis symptoms are similar to those for bacterial meningitis and include fever, headache (often described as being frontal or retro-orbital), photophobia, pain upon moving the eyes, meningismus and sometimes a vesicular/petechial rash (rubella-like if echoviruses and coxsackieviruses are causative).

Constitutional symptoms-e.g., malaise, myalgia, anorexia, nausea, abdominal pain, diarrhea-may accompany fever. Mild lethargy is common. Occurrence of stupor, marked confusion or coma is rare, and these symptoms generally are not indicative of a meningitis with a viral cause. Gastrointestinal and respiratory symptoms may occur when infection is caused by enteroviruses.

The CSF profile is abnormal in viral meningitis. Characteristics include usually normal opening pressure, slightly increased protein and normal glucose (glucose is below normal for bacterial meningitis). The CSF leukocyte concentration is elevated with lymphocytic pleocytosis (polymorphonuclear neutrophils may predominate during the first 48 hours of meningitis, especially in some enteroviral infections). Bacteria are absent on Gram stain.

Mainstay of Treatment
Antimicrobial therapy is not effective for most viral agents; symptomatic therapy is the mainstay for treatment of most cases of viral meningitis. Hospitalization generally is not required, with case-specific exceptions, e.g., patients with deficient humoral immunity. Duration of illness is generally 10 days or less. Sequelae to viral meningitis, lasting a year or more, may include weakness, muscle spasm, insomnia and personality changes; paralysis is unusual although transient paresis and encephalitic manifestations may occur. Recovery from viral meningitis is usually complete for adults. The prognosis for infants and neonates is not as good-learning disabilities, hearing loss and other neurologic sequelae have been reported.

Because agent identification is often not done, difficult to determine or not available until after recovery, infection control is an important consideration. Enteroviruses are transmitted by the fecal-oral route and are among the more common causes of viral meningitis. The CDC recommends contact isolation in addition to Standard Precautions for neonates and young children diagnosed with enterovirus infection, including enteroviral meningitis. The National Institutes of Health Clinical Center practices a more conservative approach for management of meningitis with unclear etiology: Contact isolation is practiced for the duration of the illness for each patient diagnosed with aseptic meningitis. If a nonenteroviral diagnosis is established, infection control guidelines are then modified per the specific infectious agent identified. Generally, investigation of contacts or a source of infection is not indicated.

Case Study
Pending identification of the bacteria, D.F. is placed on droplet precautions and responds quickly to broad-spectrum antibiotic therapy. Droplet precautions are discontinued after 24 hours of antibiotic therapy and Standard Precautions alone are resumed. Culture results are positive for L. monocytogenes, a bacteria that is not transmitted person-to-person and for which antibiotic prophylaxis of contacts is not indicated. D.F. continues a speedy recovery.

Barbara Fahey is a nurse consultant with the Hospital Epidemiology Service, Office of the Director, Clinical Center, National Institutes of Health, Bethesda, MD.

Table 1: Most Common Agents Associated With Meningitis
Bacteria
Escherichia coli**Neisseria meningitidis*
Group B streptococciPseudomonas species**
Haemophilus influenzae*Streptococcus pneumoniae*
Listeria monocytogenes*
Virus***
AdenovirusEchovirus
Herpes simplexLymphocytic choriomeningitis virus
Arbovirus
Measles
Enteroviruses (picornaviruses)
Mumps
CoxsackievirusVaricella-zoster
* Can be normal oral pharyngeal flora. Conditions such as sinusitis, otitis media, upper respiratory tract infection, lower respiratory tract infection and trauma to the ears, nose or sinuses may predispose to nasopharyngeal epithelial cell infection, which in turn may result in bacteremia (transient or persistent), which in turn may result in bacteria traversing the blood-brain barrier into the CSF.
** Can be normal gastrointestinal flora. Entry into the central nervous system facilitated by trauma, neurosurgical procedures, lumbar puncture and spinal anesthesia.
*** Entry to body occurs via oral, oral-fecal or respiratory route. Virus replicates and spreads to brain via bloodstream.

 

Table 2: Cerebrospinal Fluid Analysis Findings
CSF CharacteristicNormal RangeSuggestive of Bacterial MeningitisSuggestive of Viral Meningitis
ColorClearCloudyCloudy
Red blood cell countNoneNoneNone
Gram stainNegativeUsually PositiveUsually Negative (60%-90%)
PressureLess than 200 mm H2OAbove normalNormal
Protein15-45 mg/dLAbove normalAbove normal
Glucose50-75 mg/dLBelow normalUsually normal or below normal
Lymphocytic pleocytosisNonePositive with neutrophilic pleocytosisPositive with lymphocytic pleocytosis

 

Table 3: Predominant Bacterial Pathogens Causing Meningitis by Age Group
Age GroupBacterial Pathogen
NeonatesEnteric bacteria
Gram-negative bacilli
Group B streptococci
Pseudomonas species
Listeria monocytogenes
Children
(> 1 month)
Haemophilis influenzae
Neisseria meningitidis
Adults bacilli*Meningococci species
Pneumococci species
Aerobic gram-negative
* Not as common as meningococci and pneumococci but identified with increasing frequency, especially among the elderly.

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