Gram positive diplococci in CSF which grew strep. pneumo
Today we discussed meningitis, a serious infection that requires prompt initiation of life or neurological function-saving therapy before confirming the diagnosis. Although the discussant was, well, substandard, some important points still came across
(for those not there, the discussant was me, so no emails necessary)
Some issues that came up:
Common sources of infection in nursing home patients:
1) Urinary tract
2) Pneumonia (would be 'healthcare associated'- different abx coverage)
3) Skin
Reasons for a patient not to improve despite appropriate abx for an infection:
1) Not receiving therapy (non-adherence, vomiting, etc)
2) Resistant organism
3) Wrong diagnosis
4) Source not being penetrated (e.g. underdosed, abscess)
5) Persistent source not dealt with (e.g. osteomyelitis, sacral ulcer)
Common organisms in meningitis:
1) St. pneumo
2) N. meningitidis
3) H. flu
4) Listeria
Order depends on patient; listeria more common in older, immunocompromised. Think of unusual causes in right setting (e.g. cryptococcus, TB). Even though cryptococcal meningitis (which may present subacutely) comes to mind in HIV, invasive st. pneumo infections are far more common in HIV than in the general population.
Important risk factors to ask about:
Travel, contacts, HIV RFs, sinus or ear infections, injection drugs, head trauma.
The lack of all of fever, altered mental status, or neck stiffness virtually rules out meningitis
Some physical exam points:
1) Kernig's and Brudzinski's signs were described a century ago in patients with end-stage TB meningitis. They have low sensitivity, but high specificity.
2) Jolt accentuation (i.e. patient turns own head horizontally at 2-3 /second) is 100% sensitive, but very non-specific. Therefore, lack of it essentially rules out the diagnosis (although the JAMA article excluded immunocompromised patients, so be careful)
Empiric treatment (i.e. before CT scan, before LP. Ideally after blood cultures)
1) ceftriaxone 2g (for NM)
2) vancomycin 1g (for SP- there is pen-resistant SP in the community)
3) ampicillin 2g (if suspect listeria)
4) dexamethasone 10mg (with antibiotics)- see references
5) +/- acyclovir if suspect HSV encephalitis (rash, sz, focal deficits)- need to hydrate aggressively
Tailor Abx once culture result back +/- HSV PCR is back
LP is mandatory! Even though Abx are started, you need a diagnosis.
Causes of very low CSF glucose
1) Bacterial meningitis
2) TB
3) Fungal
4) HSV encephalitis
Some references:
