Cardiac Tamponade as Manifestation of Rickettsial Infection

Abstract

INTRODUCTION: Rapidly fatal septic shock is well known with rickettsiae that do not grow on routine cultures and require different antibiotics. We describe here a case of septic and obstructive shock due to rickettsial infection that manifested with an atypical presentation (without rash). CASE PRESENTATION: A 68 year old male with nonsignificant past medical history was transferred from outside hospital with worsening hemodynamic status, intubated, on mechanical ventilation and pressor support. Patient had presented with a history of high grade fevers, and non-productive cough for a week. Physical examination was then remarkable for crepitations at the base of the left lung. Patient had received ceftriaxone, and azithromycin as empiric coverage for presumptive diagnosis of community acquired pneumonia. Laboratory data on presentation revealed leukocytosis, thrombocytopenia, hyponatremia, a high anion gap metabolic acidosis and acute renal failure. Patient had an APACHE II score of 37 on presentation, and was admitted to the intensive care unit for escalation of care, and drotrecogin infusion. Cultures were sent, and empiric antibiotic therapy initiated with cefepime, vancomycin, azithromycin, and metronidazole. On day 4 of hospitalization, patient developed new onset hemodynamically unstable rapid atrial fibrillation converted to normal sinus rhythm by direct current cardioversion. EKG showed electrical alternans. 2 D echocardiogram revealed pericardial effusion with tamponade physiology. Subxiphoid pericardiocentesis drained 600 cc hemorrhagic fluid. Analysis revealed 1740000 red blood cells per cu.mm, consistent with hemopericardium. Serologic titers for rickettsia were sent, and doxycycline added to the regimen. Fluid cultures were negative for bacteria and acid fast bacilli (AFB). Rickettsial serologies revealed positive RMSF IgM (1:128), IgG (1:512), Ehrlichia IgG (>1:2048), and R typhi IgG (1:256). DISCUSSIONS: Rickettsial diseases have a case-fatality rate of 23% unless treated early and appropriately. Early diagnosis remains a challenge due secondary to difficulty staining with ordinary bacterial stains. It is also difficult to be cultivated in cell-free medium, and growth requires living host cells (1). Epidemiological trends show fall in incidence in 1949 secondary to introduction of tetracycline antibiotics, with increased incidence lately due to a decline in use of tetracycline antibiotics as first line agents in many other infections. Rocky mountain "spotless" fever occurs more often in older and black patients. Pulmonary involvement is suggested by cough, and radiologic evidence of alveolar infiltrates, interstitial pneumonia, and pleural effusion. Pulmonary edema with impairment of ventilation, and adult respiratory distress syndrome (ARDS) requires oxygen therapy, and mechanical ventilation. Cardiac complications are seen in 5-25% of patients including hypotension due to shock, myocarditis and arrhythmias (2). Pericardial effusion has been reported as a manifestation of scrub typhus, with 58% incidence of pericarditis by autopsy in this rickettsial infection. Endothelial cell invasion by rickettsia during infection causes vasculitis, which may lead to hemorrhagic pericardial effusion. Early clinical diagnosis is key. Serology is the usual method for confirmation of diagnosis. The diagnostic titer is 1:64 for indirect immunofluorescence assay, the most sensitive, and specific test. CONCLUSION: We saw severe hemorrhagic pericardial effusion causing tamponade in severe rickettsial sepsis. Cross-reactivity within the spotted fever or typhus group precludes speciation of rickettsiae. It is important to recheck for a change in the IgM titer 7-14 days after the initial specimen.