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Streptococcus pneumoniae, N. meningitidis, Esche
richia coli K1, and S. agalactiae (Group B strep). CSF
Cryptococcal antigen and India ink stain should be
considered in patients who have HIV disease or HIV
risk factors.
III.Treatment of acute bacterial meningitis
Antibiotic Choice Based on Age and Comorbid
Medical Illness
Age Organism Antibiotic
Neonate E. coli, Group B Ampicillin and
strep, Listeria ceftriaxone or
monocytogenes cefotaxime
1-3 months S. pneumoniae, Ceftriaxone or
N. meningitidis, cefotaxime and
H. influenzae, S. vancomycin
agalactiae, Liste
ria, E. coli
3 months to 18 N. meningitidis, S. Ceftriaxone or
years pneumoniae, H. cefotaxime and
influenzae vancomycin
18-50 years S. pneumoniae, Ceftriaxone or
N. meningitidis cefotaxime and
vancomycin
Older than 50 N. meningitidis, S. Ampicillin and
years pneumoniae ceftriaxone or
Gram-negative cefotaxime and
bacilli, Listeria, vancomycin
Group B strep
Neurosur S. aureus, S. Vancomycin and
gery/head in epidermidis Ceftazidime
jury Diphtheroids,
Gram-negative
bacilli
Immunosuppr Listeria, Gram Ampicillin and
ession negative bacilli, S. Ceftazidime (con
pneumoniae, N. sider adding
meningitidis Vancomycin)
CSF shunt S. aureus, Gram Vancomycin and
negative bacilli Ceftazidime
Antibiotic Choice Based on Gram s Stain
Stain Results Organism Antibiotic
Gram's (+) S. pneumoniae Vancomycin and
cocci S. aureus, S. ceftriaxone or
agalactiae (Group cefotaxime
B)
Gram's (-) N. meningitidis Penicillin G or
cocci chloramphenicol
Gram's (-) H. influenzae Third-generation
coccobacilli cephalosporin
Gram's (+) Listeria Ampicillin, Penicil
bacilli monocytogenes lin G + IV
Gentamicin ±
intrathecal
gentamicin
Gram's (-) ba E. coli, Klebsiella Ceftazidime +/
cilli Serratia, Pseudo aminoglycoside
monas
Recommended Dosages of Antibiotics
Antibiotic Dosage
Ampicillin 2 g IV q4h
Cefotaxime 2 g IV q4-6h
Ceftazidime 2 g IV q8h
Ceftriaxone 2 g IV q12h
Chloramphenicol 0.5-1.0 gm IV q6h
Gentamicin Load 2.0 mg/kg IV, then 1.5
mg/kg q8h
Nafcillin/Oxacillin 2 g IV q4h
Penicillin G 4 million units IV q4h
Rifampin 600 mg PO q24h
Trimethoprim 15 mg/kg IV q6h
sulfamethoxazole
Vancomycin 1.0-1.5 g IV q12h
A.In areas characterized by high resistance to penicil
lin, vancomycin plus a third-generation cephalosporin
should be the first-line therapy. H. influenzae is usually
adequately covered by a third-generation cephalo
sporin. The drug of choice for N. meningitidis is penicil
lin or ampicillin. Chloramphenicol should be used if the
patient is allergic to penicillin. Aztreonam may be used
for gram-negative bacilli, and trimethoprim
sulfamethoxazole may be used for Listeria.
B.In patients who are at risk for Listeria meningitis,
ampicillin must be added to the regimen. S. agalactiae
(Group B) is covered by ampicillin, and adding an
aminoglycoside provides synergy. Pseudomonas and
other Gram-negative bacilli should be treated with a
broad spectrum third-generation cephalosporin
(ceftazidime) plus an aminoglycoside. S. aureus may
be covered by nafcillin or oxacillin. High-dose
vancomycin (peak 35-40 mcg/mL) may be needed if the
patient is at risk for methicillin-resistant S. aureus.
C.Corticosteroids. Audiologic and neurological
sequelae in infants older than two months of age are
markedly reduced by early administration of dexameth
asone in patients with H. influenzae meningitis. Dexa
methasone should be given at a dose of 0.15 mg/kg
q6h IV for 2-4 days to children with suspected H.
influenzae or pneumococcal meningitis. The dose
should be given just prior to or with the initiation of
antibiotics.
Pneumonia
Community-acquired pneumonia is the leading infectious
cause of death and is the sixth-leading cause of death
overall.
I.Clinical diagnosis
A.Symptoms of pneumonia may include fever, chills,
malaise and cough. Patients also may have pleurisy,
dyspnea, or hemoptysis. Eighty percent of patients are
febrile.
B.Physical exam findings may include tachypnea,
tachycardia, rales, rhonchi, bronchial breath sounds,
and dullness to percussion over the involved area of
lung.
C.Chest radiograph usually shows infiltrates. The
chest radiograph may reveal multilobar infiltrates,
volume loss, or pleural effusion. The chest radiograph
may be negative very early in the illness because of
dehydration or severe neutropenia.
D.Additional testing may include a complete blood
count, pulse oximetry or arterial blood gas analysis.
II.Laboratory evaluation
A.Sputum for Gram stain and culture should be
obtained in hospitalized patients. In a patient who has
had no prior antibiotic therapy, a high-quality specimen
(>25 white blood cells and
help to direct initial therapy.
B.Blood cultures are positive in 11% of cases, and
cultures may identify a specific etiologic agent.
C.Serologic testing for HIV is recommended in
hospitalized patients between the ages of 15 and 54
years. Urine antigen testing for legionella is indicated
in endemic areas for patients with serious pneumonia.
III.Indications for hospitalization
A.Age >65years
B.Unstable vital signs (heart rate >140 beats per
minute, systolic blood pressure
rate >30 beats per minute)
C.Altered mental status
D.Hypoxemia (PO2
E.Severe underlying disease (lung disease, diabetes
mellitus, liver disease, heart failure, renal failure)
F.Immune compromise (HIV infection, cancer,
corticosteroid use)
G.Complicated pneumonia (extrapulmonary infection,
meningitis, cavitation, multilobar involvement, sepsis,
abscess, empyema, pleural effusion)
H.Severe electrolyte, hematologic or metabolic abnor
mality (ie, sodium
absolute neutrophil count
> 2.5 mg/dL)
I.Failure to respond to outpatient treatment within 48 to
72 hours.
Pathogens Causing Community-Acquired Pneu-
monia
More Common Less Common
Streptococcus pneumoniae Staphylococcus aureus
Haemophilus influenzae Gram-negative bacilli
Moraxella catarrhalis Pneumocystis carinii
Mycoplasma pneumoniae Mycobacterium tuberculosis
Chlamydia pneumoniae
Legionella species
Viruses
Anaerobes (especially with
aspiration)
IV.Treatment of community-acquired pneumonia
Recommended Empiric Drug Therapy for Pa-
tients with Community-Acquired Pneumonia
Clinical Situa- Primary Treat- Alternative(s)
tion ment
Younger (
yr) outpatients biotics doxycycline
without under- (azithromycin,
lying disease clarithromycin,
dirithromycin,
or
erythromycin)
Older (>60 yr) Levofloxacin or Beta-lactamase in
outpatients cefuroxime or hibitor (with
with underlying Trimethoprim- macrolide if
disease sulfa- legionella infection
methoxazole suspected)
Add
vancomycin in
severe, life
threatening
pneumonias
Gross aspira- Clindamycin IV Cefotetan,
tion suspected ampicillin/sulbactam
A.Younger, otherwise healthy outpatients
1.The most commonly identified organisms in this
group are S pneumoniae, M pneumoniae, C
pneumoniae, and respiratory viruses.
2.Erythromycin has excellent activity against most of
the causal organisms in this group except H
influenzae.
3.The newer macrolides, active against H influenzae
(azithromycin [Zithromax] and clarithromycin
[Biaxin]), are effective as empirical monotherapy for
younger adults without underlying disease.
B.Older outpatients with underlying disease
1.The most common pathogens in this group are S
pneumoniae, H influenzae, respiratory viruses,
aerobic gram-negative bacilli, and S aureus. Agents
such as M pneumoniae and C pneumoniae are not
usually found in this group. Pseudomonas
aeruginosa is rarely identified.
2.A second-generation cephalosporin (eg,
cefuroxime [Ceftin]) is recommended for initial
empirical treatment. Trimethoprim-sulfamethoxazole
is an inexpensive alternative where pneumococcal
resistance to not prevalent.
3.When legionella infection is suspected, initial
therapy should include treatment with a macrolide
antibiotic in addition to a beta-lactam/beta
lactamase inhibitor (amoxicillin clavulanate).
C.Moderately ill, hospitalized patients
1.In addition to S pneumoniae and H influenzae,
more virulent pathogens, such as S aureus,
Legionella species, aerobic gram-negative bacilli
(including P aeruginosa, and anaerobes), should be
considered in patients requiring hospitalization.
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