Internal Medicine

0521779407-10 CUNY1086/Karliner 0 521 77940 7 June 6, 2007 17:44

Laxative Abuse Legionella Infections 887

■For those with underlying psychological factors or altered self-image,

prognosis depends on the success of psychiatric treatment

■For those who progress to cathartic colon, chronic constipation

refractory to medical therapy may occur

LEGIONELLA INFECTIONS

RICHARD A. JACOBS, MD, PhD

history & physical

History

■Legionella are small, fastidious (grow on charcoal yeast extract, but

not routine culture media), slow-growing (3–5 days for culture to

turn positive), aerobic, Gram-negative bacilli.

■Over 40 species and 60 serogroups, but most human infections

caused by L. pneumophila serogroups 1, 4, and 6

■Other species that less commonly cause human infection include L.

micdadei, L. bozmonii. L. dumoffi, L. longbeachae and L. wadswor-

thii.

■Natural habitat of Legionella is water; low numbers of organisms in

natural bodies of water (lakes, rivers); larger numbers in reservoirs

(water towers, water condensers, potable water distribution systems)

■Transmission by aerosolization and inhalation of contaminated

water or aspiration after colonization of the upper airways

■Risk factors include immunosuppression, chronic lung disease,

smoking and older age.

Signs & Symptoms

■Pneumonia most common clinical syndrome; manifestations simi-

lar to other causes of pneumonia; cough productive of small amounts

of sputum; fever almost always present (25% with temperatures

above 40◦C); GI symptoms (abdominal pain, nausea, vomiting) com-

mon, with diarrhea in up to 50%; headache and confusion also

common; exam frequently reveals rales or consolidation

■Extrapulmonary infection uncommon and results from hematoge-

nous spread from lungs; cardiac involvement (myocarditis, peri-

carditis, endocarditis) most common extrapulmonary site; other

sites (skin, pyelonephritis, peritonitis, dialysis shunts, wounds)

described, particularly in the immunosuppressed patient