to survive, multiply, and colonize. Patients with uncontrolled diabetes have high sugar content in their sweat and connective tissues, which can become a perfect energy source for bacterial colonization and subsequent infection. To make matters worse, diabetic patients also frequently have immunosuppression and microvasculopathy.”
Systemic infection with any microbe can present with nonspecific features of fever, tachycardia, leukocytosis, altered mental status, etc. As infection progresses, patients can start looking sicker, and develop decompensation in various organ systems, as following:
aOther penicillins (such as Penicillin V or G, amoxicillin, ampicillin) are good against the Streptococcus group (S. viridans, S. pneumoniae, S. pyogenes) but not against staph, as staph usually have B-lactamases which deactivate penicillins.
1 Cephalosporins can be given in patients with mild penicillin allergy (e.g., rash), but are contraindicated in patients with severe penicillin allergy (e.g., anaphylaxis, Stevens-Johnson syndrome, allergic interstitial nephritis).
cIV forms are ceftriaxone, cefotaxime, and ceftazidime. Oral forms are cefpodoxime and cefdinir. These drugs have good Streptococcus/Staphylococcus coverage as well, but not as good as 1st generation cephalosporins or B-lactamase resistant narrow-spectrum penicillins.1
2 Meropenem or imipenem may be the right answer in a patient with prolonged hospitalization and evidence of active gram-negative infection who does not improve despite adequate antibiotic therapy. The only difference of coverage in between (meropenem, doripenem, imipenem) and ertapenem, is that ertapenem does not cover Pseudomonas.
fThe old dictum of treating above-diaphragm infection (e.g., lung abscess) with clindamycin and below-diaphragm infection (e.g., intestinal infection or perforation) with metronidazole no longer applies. Clindamycin is no longer preferred due to increased risk of C. difficile. The preferred antibiotics for treatment of aspiration pneumonia now are amoxicillin-clavulanate, or third-generation cephalosporin + metronidazole.
Cellulitis without MRSA risk factorsa
Ceftriaxoneb + metronidazole
Infections with risk factor for Pseudomonasc
a MRSA risk factors: IVDA (intravenous drug abuse), human immunodeficiency virus (HIV) positive, recent prior antimicrobial therapy, hemodialysis, recent hospitalization, residence in long-term care facility such as nursing homes, etc.
Potential autoimmune complication of strep infection (e.g., erysipelas, cellulitis, strep throat) is Rheumatic fever and postinfectious glomerulonephritis (glomerulonephritis can also occur with staph infection).
MRSA risk factora
aRisk factors for MRSA include – IVDA (intravenous drug abuse), HIV positive status, recent prior antimicrobial therapy, hemodialysis, recent hospitalization, residence in long-term facilities such as nursing homes, etc.
High risk population for Infective endocarditisa
aExamples of high risk conditions include prosthetic cardiac valve (including bioprosthetic heart valve), previous infective endocarditis, unrepaired cyanotic congenital heart disease, etc. Please refer to infective endocarditis section discussed later in this chapter.
The following severe soft tissue infections usually have signs of systemic toxicity (Toxic shock syndrome is included in this table as sometimes cellulitis can lead to toxic shock syndrome and cause severe systemic toxicity).
Staph, aureus a
One broad spectrum antibiotic (meropenem or piperacillin/tazobactam or ampicillin-sulbactam) +
aThis is due to colonization or infection with Staph. aureus that produces toxic-shock-syndrome-toxin (TSST). This toxin is unique in that it non-specifically activates T-helper cells, which release excess inflammatory mediators into the bloodstream causing SIRS, sepsis and even death.
+ Stiff neck or other signs of meningismusa
aSigns of meningeal inflammation include photophobia, Kernig’s sign (inability to straighten the leg when hip is flexed), and Brudzinski’s sign (neck flexion causes reflexive flexion of hips and knees).
aIf there is a suspicion for space-occupying lesion, perform computed tomography (CT) scan prior to lumbar puncture as lumbar puncture can precipitate brainstem herniation in patients with elevated intracranial pressure (ICP). Also give antibiotics, as diagnostic workup should not delay life-saving antibiotic therapy.
Empiric IV antibiotics of choicea
Vancomycin b + Ceftriaxone or cefotaxime
aConsider adding dexamethasone (except in neonates < 6 weeks old). In children, the greatest benefit of dexamethasone is in suspected H. influenzae meningitis; in adults in pneumococcal meningitis. It should be given concurrently with or immediately before the first dose of antibiotics, there’s probably no benefit if the corticosteroid is given after antibiotics are initiated. It reduces inflammation and decreases risk of neurologic complications, such as hearing loss.
Close contacts of N. meningitis patients—all household members, childcare center, military recruits in training center, and roommates/dorm mates. (Note: classmates or coworkers are not automatically considered as close contact.)
Rickettsia causing Rocky Mountain spotted fever (RMSF)a
Usually presents with acute confusion and personality changes, thus CT scan is done prior to lumbar puncture. CT scan may reveal unilateral or bitemporal lobe abnormalities or hemorrhage. With clinical and/or CT findings suggestive of HSV-1; NSIM is IV acyclovir.
NSIM is lumbar puncture with HSV-1 PCR (most accurate test). CSF fluid typically shows increased lymphocytes + increased RBCs. After that, brain magnetic resonance imaging (MRI) is recommended to assess temporal lobe involvement.
A 25-year-old male presents to the hospital with fever and seizures. Patient is diagnosed with herpes viral encephalitis. After few days, patient develops hypersexuality and is seemingly very apathetic to other issues. He is also found to be putting things in his mouth a lot (hyperorality, which is tendency to examine objects by mouth).
May be presentd
May be presente
Presentation: Fever, myalgias (generalized muscle pain), headache, and upper respiratory symptoms, such as runny nose and nonproductive cough (due to the postnasal drip). Chest X-ray (CXR) may show increased interstitial marking due to viral bronchitis.
Rx: Antivirals (Oseltamivir or Zanamivir). Indication for antiviral treatment has been broadened. The only group that might not be treated is healthy patients < 65 years of age with uncomplicated influenza who present after >48 hours of symptoms, or who are already feeling better or pediatric population.
eLobar pneumonia with multiple air bronchograms and absence of significant tracheal deviation (If there was lung opacity similar to this but with tracheal deviation to the same side and no air bronchogram, the diagnosis would be more likely atelectasis).
fLung abscess is commonly a sequelae of aspiration (look for risk factors of aspiration, e.g., advanced dementia, alcoholism). NSIM is sputum gram stain/culture and CT thorax to rule out obstructive pathology. Empiric antibiotics should cover anaerobes (e.g., amoxicilin-clavulanate). Antibiotics is continued until chest imaging is clear (might take weeks).
gIf you think the patient is sick (e.g., septic, hypoxemic, and/or immunocompromised), then NSIM is to hospitalize the patient and give IV antibiotics (after taking blood cultures). There is a CURB-65 criteria to help you make that decision too.