Bacterial Pneumonia 1 Flashcards
P. aeruginosa bacteriology
gram - rods. strict aerobes. non-fermenters. oxidase pos. makes pyocyanin and pyoverdin. has an anti-phagocytic slime layer (glycocalyx). minimal growth requirements. resistant to detergents and disinfectants. extremely Ab resistant
P. aeruginosa pathogenesis
environmentally ubiquitous. nosocomial pathogen. vulnerable people are ppl with extensive burn patients, immunosuppressed, chronic respiratory disease, long term cath, IVs, neonates
community acquired ways to get p. aeruginosa
endocarditis in IV drug users, otitis externa/folliculitis in underchlorinated hot tubs. osteochondritis in puncture wounds through sneakers. corneal infection in contact lens wearers
virulence factors for P. aeruginosa
endotoxin: cell wall component. Exotoxins: exoA, type 3 secretion sys, exoS. Enzymes: elastase, protease. pyocyanin (messes with electron transfer system). glycocalyx (antiphagocytic). efflux pumps: toss antibiotics back out of cell
p. aeruginosa exam
can infect anywhere, predominantly nonsocomial UTI, CF pneumonia, burns. if immunosuppressed, can progress to sepsis: pneumonia, endocarditis, meningitis, ecthyma gangrenosum
p. aeruginosa nonbacteremic vs bacteremic pneumonia chest x-ray
nonbacteremic: resembles S. aureus, diffuse bronchopneumonia (distinct nodules and small areas of radiolucency) and pleural effusions
bacteremic: rapid progression, poorly defined hemorrhagic, often subpleural, nodular areas with a small central area of necrosis. multiple umbilicated nodules with hemorrhagic parenchyma
p. aeruginosa lab
aerobic and anaerobic cultures. culture from relevant fluids. nonfermenting, oxidase +. metallic sheen on trile sugar iron agar. green color on nutrient agar. fruity aroma.
p. aeruginosa treatment
remove/change catheters/IVs. Give Abs but also check for Ab sensitivity. UTIs: ciprofloxacin. everything else: piperacillin/tazobactam or ticarcillin/clavulanate plus gentamicin of amikacin
p. aeruginosa prevention
keep neutrophil count up. remove/change catheters/IVs. burn unit precautions. handwashing. experimental vaccines are available to CF patients.
B. cepacia bacteriology/pathogenesis
grows easily in IV fluid/irrigation solutions. very limited ability to infect otherwise healthy patients, may be considered colonizing rather than infecting. Found in people with CF, pneumonia, UTIs from caths, IV septicemia, and foot rot
B. cepacia and cystic fibrosis
CF/ cepacia pneumonia experience has become more common as CF longevity has improved. Cepacia in CF centers forms outbreaks. Cepacia syndrome: accelerated pulmonary course with rapidly fatal bacteremia
B. cepacia diagnosis and treatment
no pyocyanin. no treatment required in healthy patient. if CF, cancer, HIV: treat with trimethoprin sulfamethoxazole, alternate 3rd gen cephalo, ciproflox, ampicillin, chloramphen, meropenem. experimental vaccines available for CF people
b. pseudomallei bacteriology
melioidosis. transmission by direct contact with contaminated water and soil. motile gram - rod. rare human to human transmission. Few cases in US per year
B. pseudomallei pathogenesis
initial symptoms flulike, muscle tightness, light sensitivity. range of severity: acute local to septicemia with abscesses. septicemia can lead to cyanosis, flushing, pustular eruptions. risk factors: diabetes, renal dysfunction, chronic pulmonary disease. milder infections may resolve then reactivate. resembles TB in lungs.
b. pseudomallei diagnosis/treatment
diagnose from history and culture/gramstain. PCR and immunofluorescence assays exist. imaging studies helpful: multiple small abscesses in liver and spleen. treat with ceftazidime or combi w/ trimeth sulf or amoxicillin.
b. mallei bacteriology
nonmotile. used as a biowarfare agent. could be used against humans. rare zoonosis, assumed infected discharge passes through broken skin. maintained in animal reservoirs, not soil or water.
b. mallei pathogenesis
human to human transmission rare. flulike symptoms. acute localized: nodule at infection site. acute pulmonary: bronchitis-> pneumonia. acute septicemic: fulminant, multiorgan involvement. facry = chronic form of infection
b. mallei diagnosis and treatment
use history, culture and gram stain. PCR and immunofluorescence exists. long term Ab treatment with amoxicillin and clavulanate. inform CDC if no evidence of animal occupational exposure!
chlamydia pneumonia history/presentation for c. pneumoniae
3-4 week incubation. infection common, often asymptomatic. fever more often present in first few days, absent by exam. rhonchi and rales present in mild disease. headache, sinus percussion tenderness. symptoms may be prolonged.
chlamydia pneumonia history/presentation for c. psittaci
exposure to sick birds. incubation 5-14 days. abrupt onset. asymptomatic to severe pneumonia. nonproductive cough, chest pain, splenomagaly. fever most common symptom. horder spots: erythematous, blanching, maculopapular rash. severe cases may progress to meningitis, encephalitis, endocarditis
chlamydia pneumonia history/presentation for c. trachomatis
12000 cases from infected mothers. nasal obstruction and discharge, cough, tachypnea, inclusion conjunctivitis, middle ear abnormality, scattered crackles on sounds. most patients afebrile and only moderately ill. may also present in a severely immunocompromised adult
diagnostics for c. pneumoniae
microimmunofluorescence antibody tests, serology. cell culture impractical. chest radiograph: single subsegmental infiltrate mainly in the lower lobes.
diagnostics for c. psittaci
complement fixing or MIF antibody tests. serology. cell culture is hazardous. radiograph: consolidation in single lower lobe.
diagnostics for c. trachomatis
culture or hybridization like genital chlamydia. radiograph: bilateral interstitial infiltrates with hyperinflation.
treatment for c. pneumoniae
doxycycline. most cases are mild.
treatment for c. psittaci
tetracycline or doxycycline. usually curable in 7-14 days.
treatment for c. trachomatis
treat infants with erythromycin. if prophylactic, use oral erythromycin, not just eye ointment, as this prevents progression to pneumonia. most patients respond to appropriate antibiotics.
