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- Nosocomial Pneumonia
Viral PneumoniaCMV large cells with eosinophilic inclusions / immunocompromised HSV multinucleate / ground-glass change in nucleus / cowdry A inclusions VZV looks like HSV Measles multinucleate and giant cells Adenovirus basophilic nuclear smudges / smaller cowdry A inclusions / uncommon but bad Influenza often with bacterial superinfection RSV small cowdry type A Parainfluenza immunocompromised / eosinophilic inclusions Hantavirus interstitial pneumonia / edema and effusion
Aspergillosis associate with asthmatics Histoplasma central US / oval budding yeasts Coccidioides SW US / no budding Cryptococcus pigeon droppings Blastomyces Candidiasis immunocompromised / yeasts Malassezia furfur parenteral alimentation (TPN) Torulopsis glabrata immunocompromised / smaller yeasts Pseudoallescheria boydii immunocompromised / hyphae Parasite: ascariasis, filariasis, VLM, paragonimiasis / transient infiltrates, moderate eosinophilia Nosocomial PneumoniaIncidence with mechanical ventilation 10-60% (mortality 30-70%) Prevention: semirecumbent position / continuous aspiration ventilator mechanism Use lower threshold of positive PCB culture 10e2 (not 10e3) Usual organisms: Pseudomonas, Acinetobacter, gram positives Treatment: piperacillin/tazobactam +/- cipro ceftazidime/tobramycin meropenem may need to add vancomycin if MRSA suspected Aspiration pneumonia Community acquired: anaerobes (necrosis, abscess, empyema, pyopneumothorax) Nosocomial: GNR, S. aureus
Community acquired: clindamycin or metronidazole + b-lactam Nosocomial: aminoglycoside or ciprofloxacin + antipseudomonal B-lactam or clindamycin + aztreonam Pneumococcus (see micro) ⅔ of bacteremic community-acquired pneumonias / sporadic (most in Winter) / 5 to 25% of healthy persons are carriers / > 80 serotypes (type 3 is worst) / stages: congestion red hepatization gray hepatization resolution Presentation: often preceded by a URI / sudden onset, single shaking chill; persistent chills suggest another diagnosis / fever (38-40.5° C / 100.4-105° F), pain with breathing on the affected side (pleurisy), cough, dyspnea, and sputum / pain may be referred and, with lower lobe involvement, may suggest intra-abdominal sepsis, such as appendicitis / HR 100-140 / nausea, vomiting, malaise, and myalgias / dry cough purulent, blood-streaked or rusty sputum Complications : progressive pneumonia, ARDS, sepsis contiguous infection (e.g., empyema or purulent pericarditis) pleural effusions are found in about 25% of patients by chest x-ray, but < 1% have empyema. Bacteremia septic arthritis, endocarditis, meningitis, and peritonitis (in patients with ascites) pulmonary superinfections Diagnosis: clinical, CXR, sputum Cx / definitive diagnosis Cx of pleural fluid, blood, BAL CXR often with dense consolidation of single lobe (lobar pneumonia) with typical air bronchograms Prognosis: overall mortality rate is about 10%, and treatment has minimal effect on mortality during the first 5 days of illness / poor prognosis age extremes, especially < 1 yr or > 60 yr; positive blood cultures; involvement of > 1 lobe; a peripheral WBC count < 5000/µL; presence of associated disorders (e.g., cirrhosis, heart failure, immunosuppression, agammaglobulinemia, anatomic or functional asplenia, and uremia); involvement of certain serotypes (especially 3 and 8); and development of extrapulmonary complications (e.g., meningitis or endocarditis). mildly ill usu. defervesce in 24-48 h; however, seriously ill patients, particularly those with the poor prognostic features noted above, often require ≥ 4 days to become afebrile. Therapy should not be modified if there is gradual clinical improvement and the etiology is confirmed. when patients do not improve, these factors should be considered: wrong etiologic diagnosis, adverse drug reaction, far-advanced disease (most common), superinfection, inadequate host defenses due to associated conditions, noncompliance with the drug regimen by outpatients, antibiotic resistance of the involved strain of S. pneumoniae, and complications, such as empyema requiring drainage or metastatic foci of infection requiring a higher dosage of penicillin (e.g., meningitis, endocarditis, or septic arthritis). Treatment respiratory supportive care, blood culture, antibiotics ceftriaxone or cefotaxime or cefepime levofloxacin or gatifloxicin or moxifloxicin vancomycin +/- rifampin Note: macrolides actually are active against pneumococcus, the issues is that they may be more active in tissue, and not provide adequate blood/CSF coverage (given high propensity of Pneumococcus toward bacteremia) Prevention: pneumovax Staphylococcus 2% of community-acquired pneumonias, 10-15% of nosocomial pneumonias Infants, elderly, hospitalized, debilitated patients, children, CF, bacterial superinfection (esp., influenza A and B, IVDA (Staph. tricuspid valve endocarditis embolic pneumonia)
Like S. pneumo plus rigors, necrosis/abscess, pneumatoceles (esp. infants/children), a fulminant course / empyema is common, esp. postthoracotomy, chest tubes after trauma Diagnosis: positive sputum, blood cultures, empyema fluid, BAL CXR: bronchopneumonia (+/- abscess, effusion); lobar consolidation is uncommon / pneumatoceles strongly suggest staphylococcus / embolic staphylococcal pneumonia is characterized by multiple infiltrates that occur at discontiguous sites and tend to cavitate; this pattern suggests an endovascular source (e.g., right-sided endocarditis or septic thrombophlebitis). Treatment: MRSA occurs in 30-40% of nosocomially acquired (and community-acquired MRSA is on the rise) / consider vancomycin / otherwise, use bacteriocidal agents: oxacillin or nafcillin or cephalothin or cefamandole / clindamycin and some quinolones have activity Prognosis: mortality generally 30 to 40%, in part due to the serious associated conditions most patients have / sometimes even in normal adults / response to antibiotics slow; convalescence is prolonged Group A Strep relatively rare cause of pneumonia / epidemic > sporadic / sometimes in associations with measles, chickenpox, pertussis, influenza, streptococcal pharyngitis, scarlet fever, or toxic shock syndrome Presentation: similar to S. pneumo, but maybe less bacteremic symptoms CXR: bronchopneumonia with large pleural effusion / lobular pneumonia / abscess Labs: may see significant increase in the ASO titer with serial tests Prognosis: response to therapy tends to be slow, but overall mortality is very low Treatment: Penicillin G or cephalosporins, erythromycin, clindamycin / large pleural effusions are usually managed with repeated thoracentesis or closed catheter drainage / purulent collections and loculated effusions should be drained by tube thoracostomy GNR Only 2% of CAP but most nosocomial pneumonias / infants, the elderly, alcoholics, and debilitated or immunocompromised hosts (esp. neutropenia) / happens because sick patients’ oropharynx are colonized with GNR and then all they have to do is microaspirate Organisms: Klebsiella 1st, Pseudomonas, E. coli, Enterobacter, Proteus, Serratia, Acinetobacter Presentation: similar to other pneumonias except more rapid decline, abscess formation Diagnosis: clinical context (neutropenia, nosocomial pneumonia) / false positives from upper airway colonizers a problem (esp. if already received antibiotics then “sputum superinfection” must be distinguished from “patient superinfection”) / positive cultures from blood, pleural fluid, or BAL Treatment: cephalosporin (cefepime, Fortaz?) or imipenem or ciprofloxacin (or levaquin?) or Zosyn or Timentin +/- AG H Influenza Treatment: 30% of H. influenzae strains produce ß-lactamase and are resistant to ampicillin Bactrim 1 or 2 DS 160/800 mg bid or cefuroxime 0.25 to 1 g IV q 6 h or cefaclor 500 mg po q 6 h for adults or doxycycline 100 mg po bid / fluoroquinolones and azithromycin also active Vaccine: H. influenzae type b (Hib) conjugate Chlamydia (see micro) Presentation: similar to mycoplasmal pneumonia (pharyngitis, bronchitis, pneumonitis, cough, fever, sputum production but are not seriously ill) C. pneumoniae has been found in 5 to 10% of older adults with community-acquired pneumonia and often produces disease severe enough to require hospitalization. This organism has also been implicated in 5 to 10% of cases of nosocomial pneumonia, but relatively little is known about its epidemiology. C. trachomatis is a common cause of pneumonia in infants aged 3 to 8 wk but is not an important cause of pneumonia in older children or adults. Diagnosis: clinical but can culture, direct IF, PCR, serological Treatment: macrolide or tetracycline x 10-21 days Course: response is slower than mycoplasmal pneumonia; symptoms recur if therapy is discontinued prematurely; young adults do well, but mortality in the elderly is 5-10% Psittacosis (micro) Viral Pneumonia Children: RSV, parainfluenza virus, influenza A and B Adult: influenza A and B > adenovirus > VZV, EBV< coxsackievirus, Hantavirus Elderly: influenza, parainfluenza, RSV Immunocompromised: same as above plus CMV Presentation: bronchitis, bronchiolitis, pneumonia; usu. headache, fever, myalgia, cough, may have mucopurulent sputum Diagnosis: clinical and/or epidemiological (during flu season, associated exanthems, etc.) CXR: interstitial pneumonia or peribronchial thickening; lobar consolidation and pleural effusions uncommon (unless bacterial superinfection) Labs: WBC can be low or elevated Treatment: depends on suspected cause (anti-HSV meds, VZV, CMV (?add CMV-Ig), influenza); also must cover if suspected superimposed bacterial (usu. staph and strep) Pneumocystis carinii (PCP) (see micro) Compromised Host Ddx for non-infectious causes: pulmonary hemorrhage, pulmonary edema, radiation injury, pulmonary toxicity due to cytotoxic drugs, and tumor infiltrates Localized: bacteria, mycobacteria, fungi, or Nocardia sp Diffuse interstitial: viral, PCP, drug or radiation injury, pulmonary edema Diffuse nodular lesions: mycobacteria, Nocardia sp, fungi, or tumor Cavitary: mycobacteria, Nocardia sp, fungi, bacteria Transplant recipients with bilateral interstitial pneumonia: CMV Pleura-based consolidation: aspergillosis Post-Op Pneumonia More with thoracic or abdominal surgery / usual pathogen in empyema after chest surgery is Staphylococcus aureus. About 40% of posttraumatic pneumonias are complications of fractured ribs or chest trauma; the rest are divided about equally among skull fractures or other head injuries, other fractures, burns, and major contusions / only about 10% of such infections follow operations performed under local or IV anesthesia Causes: GNR, S. aureus, pneumococci, Haemophilus influenzae, or combinations of these.
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