routes of a meningeal infection
Hematogenous spread: entry into the subarachnoid space via the bloodstream, most common route is the meninges
- direct spread from the ear, sinus, or brain abscess ( anaerobes and viridans)
- anatomic defect of CNS due to trauma, surgery, congenital abnormality ( spina bifida), implants(shunt)
- intra-neural travel: hiv, rabies, * less common*
meningitis
inflammation of the miningies
- increased wbc in csf,
- fever
- headache
- nausea
- vomiting
- stiff neck
- rash
- bacterial is the increase in PMS (acute inflammatory exudates) and bacteria
- aseptic is most common and a viral infections
aseptic meningitidis
increase WBC with no bacteria
- most commonly assocaited with viruses ( enterovirus)
- less common are fungi, spirochetes, medications, maligncies
- most are self limiting without therapy
bacterial meningitis
- increased polys, decreased glucose, increased proteins, positive direct smear
- headache, fever, rash, stiff neck, nausea, vomiting, neurological abnormalities, change in mental status
- respiratory tract is the most common source
- -age and underlying factors may increase risk of infection
Predisposing risk of Meningitis
- alcoholism
- splenectomy
- diabetes
- prosthetic devices
- decrease in immunocompetence
possible agents of meningitis
Haemophilus influenzae type b
- streptococcus pneumoniae
- Niesseria meningitidis
- strep. agalactiae
- Listeria Monocytogens
- fungal (Crytococcus Neoformans, and immitis)
- Viruses: Entrovirus, herpes, West Nile, Mumps, Varicella
- Parasitic: Free-living amebae, Toxoplasma gondii
- TB rare
- Spirochetes Borellia burgdorheria, syphilis
antibiotics used to treat meningitis
Cross only with inflammed meninges: - Penicillin - Ampicillin -Cefurozime - ceftriaxone - ceftrazidime - Vancomycin -Cefotaxime Cross Blood Brain Barrier - Chloramphenicol - sulfonamides - SXT - rifammpin
N. Meningitidis
5% of population carry in the oropharynx
- transmitted through respiratory secretions, URT establish then enters blood stream
- DIC
- Rash is a common symptom
causes highest number of laboratory deaths, work in hood
S. Agalactiae
GBS
- treat with cephlasporins
- GCP
- narrow B hemolysis
- Cat -, CAMP +
Listeria monocytogenes
GPR
- small translucent colony with narrow B hemolysis
- umbrella motility on semisolid media
- Cat +, Esculin +, CAMP +
looks like GBS on plate so be very careful
- early infections of a baby is less than 7 days and they got it from mom
- later is within 2-3 months: family member aquired
Fungal agents
insidious onset for a month or longer
- Cryptoneoformans: encapsulated, india ink, urease +, test with cryptococcal antigen
- Cocciodies immitis: most common of fungal meningitis, , inhaled and spread. HIV pts.
