Bacterial Pneumonia 1

Question 1

P. aeruginosa bacteriology

Answer 1

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

Question 2

P. aeruginosa pathogenesis

Answer 2

environmentally ubiquitous. nosocomial pathogen. vulnerable people are ppl with extensive burn patients, immunosuppressed, chronic respiratory disease, long term cath, IVs, neonates

Question 3

community acquired ways to get p. aeruginosa

Answer 3

endocarditis in IV drug users, otitis externa/folliculitis in underchlorinated hot tubs. osteochondritis in puncture wounds through sneakers. corneal infection in contact lens wearers

Question 4

virulence factors for P. aeruginosa

Answer 4

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

Question 5

p. aeruginosa exam

Answer 5

can infect anywhere, predominantly nonsocomial UTI, CF pneumonia, burns. if immunosuppressed, can progress to sepsis: pneumonia, endocarditis, meningitis, ecthyma gangrenosum

Question 6

p. aeruginosa nonbacteremic vs bacteremic pneumonia chest x-ray

Answer 6

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

Question 7

p. aeruginosa lab

Answer 7

aerobic and anaerobic cultures. culture from relevant fluids. nonfermenting, oxidase +. metallic sheen on trile sugar iron agar. green color on nutrient agar. fruity aroma.

Question 8

p. aeruginosa treatment

Answer 8

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

Question 9

p. aeruginosa prevention

Answer 9

keep neutrophil count up. remove/change catheters/IVs. burn unit precautions. handwashing. experimental vaccines are available to CF patients.

Question 10

B. cepacia bacteriology/pathogenesis

Answer 10

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

Question 11

B. cepacia and cystic fibrosis

Answer 11

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

Question 12

B. cepacia diagnosis and treatment

Answer 12

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

Question 13

b. pseudomallei bacteriology

Answer 13

melioidosis. transmission by direct contact with contaminated water and soil. motile gram - rod. rare human to human transmission. Few cases in US per year

Question 14

B. pseudomallei pathogenesis

Answer 14

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.

Question 15

b. pseudomallei diagnosis/treatment

Answer 15

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.

Question 16

b. mallei bacteriology

Answer 16

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.

Question 17

b. mallei pathogenesis

Answer 17

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

Question 18

b. mallei diagnosis and treatment

Answer 18

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!

Question 19

chlamydia pneumonia history/presentation for c. pneumoniae

Answer 19

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.

Question 20

chlamydia pneumonia history/presentation for c. psittaci

Answer 20

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

Question 21

chlamydia pneumonia history/presentation for c. trachomatis

Answer 21

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

Question 22

diagnostics for c. pneumoniae

Answer 22

microimmunofluorescence antibody tests, serology. cell culture impractical. chest radiograph: single subsegmental infiltrate mainly in the lower lobes.

Question 23

diagnostics for c. psittaci

Answer 23

complement fixing or MIF antibody tests. serology. cell culture is hazardous. radiograph: consolidation in single lower lobe.

Question 24

diagnostics for c. trachomatis

Answer 24

culture or hybridization like genital chlamydia. radiograph: bilateral interstitial infiltrates with hyperinflation.

Question 25

treatment for c. pneumoniae

Answer 25

doxycycline. most cases are mild.

Question 26

treatment for c. psittaci

Answer 26

tetracycline or doxycycline. usually curable in 7-14 days.

Question 27

treatment for c. trachomatis

Answer 27

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.