Case Report: Infective Endocarditis… Is it in the differential diagnosis of intravenous drug users with abdominal pain?

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This case was presented at the AOA National Convention, San Diego, CA, October 1, 2007.

Background

Infective endocarditis is a challenging diagnosis having many presentations ranging from an indolent infection to septicemia with life-threatening systemic embolizations.  A case of infective endocarditis presenting as abdominal pain from renal and splenic infarcts secondary to septic emboli is described. 1

Case Report

A 32 year old male presented to the emergency department with complaints of abdominal pain for one day.  Pain is described as sharp, non-radiating, located in the right upper quadrant and epigastric area, worse with movement, and began after drinking alcohol the night before.  Patient feels nauseous, but denies vomiting or diarrhea.  Patient denies fever currently, but states he had tactile fever and chills on and off for the past few days.  He has no complaints of frequency, urgency, or dysuria, denies sick contacts or recent travel, and states he has never had this pain before.  His past medical history is significant for Hepatitis C, alcohol abuse, intravenous drug use, and depression.  Patient denies any prior surgeries and has no known drug allergies.  Social history is significant for Methadone, tobacco, alcohol, and intravenous cocaine use.  The physical exam was then conducted.  Vital signs were temperature 98.6 F, heart rate 93, respirations 20, blood pressure 138/100.  Patient appeared to be in moderate distress holding his right upper quadrant area.  Significant findings included a III/VI diastolic murmur heard best at the left sternal border and abdominal exam with tenderness of right upper quadrant and epigastric area, normal bowel sounds, soft, no guarding or rebound, liver not enlarged, and no Murphy’s sign.  Old scars from intravenous drug use were found on bilateral forearms. The rest of the physical exam was within normal limits.  The patient was initially given Zantac, Reglan, and intravenous fluids and sent for an abdominal ultrasound.  The ultrasound was limited secondary to bowel gas, but showed no gallstones or pericholecystic fluid, gallbladder wall measured 4.3 mm, common bile duct was normal.  Patient still complained of severe abdominal pain, so was sent for CT with intravenous contrast of Abdomen and Pelvis.  The CT scan revealed hypodense areas in the right kidney and medial portion of the spleen, consistent with infarction.  Given the patient’s past medical history, infarction of the right kidney and spleen secondary to septic emboli from endocarditis was suspected.  Three sets of blood cultures were drawn and case was discussed with the infectious disease physician.  Patient was started on Vancomycin and Gentamicin pending culture sensitivies and admitted for an echocardiogram and long term antibiotic treatment.

All three sets of blood cultures were positive for Streptococcus Intermedius sensitive to Vancomycin.  Transthoracic echocardiogram revealed mild aortic insufficiency, but no visible vegetations.  Patient had a PICC line inserted and completed a six week course of antibiotics prior to discharge.

Summary of the Laboratory and Radiology Results

CBC: WBC 17.3/Hg 14.9/Hct 43/Pl 241

BMP:  Na 136/K 4.9/Cl 100/CO2 24/BUN 14/Cr 1/Gl 92/Ca 9.1

LFT’s:  4.5/7.7/51/102/0.8/64

Amylase: 45

Lipase: 23

PT/INR/PTT:  10/1/26.7

HBsAg: nonreactive

HBsAB: nonreactive

Anti-HCV: reactive

HIV: nonreactive

Blood Cultures x 3:  Streptococcus Intermedius

Abdominal Ultrasound:  Limited exam due to bowel gas.  Neck of the gallbladder not visualized.  No gallstones, no pericholecystic fluid, gallbladder wall measured 4.3 mm (slightly above normal), common bile duct within normal limits.  No sonographic Murphy’s sign.

CT (+) Abdomen/ Pelvis:  A wedge shaped cortically based hypodense area is noted in the interpolar region of the right kidney.  Similar linear area of hypoattenuation is seen in the medial portion of the spleen.  Provided patient’s history of fever and active IV drug use, findings most likely represent areas of infarction secondary to septic emboli from an endocarditis.  Recommend echocardiography to rule out bacterial vegetations.

Echocardiogram:  Normal aortic and mitral valves.  Normal left ventricle.  Mild aortic insufficency.  No vegetations visualized.

Figure 1: Area of hypoattenation in the medial portion of the spleen
Figure 1: Area of hypoattenation in the medial portion of the spleen
Figure 2: A wedge shaped cortically based hypodense area is noted in the interpolar region of the right kidney.
Figure 2: A wedge shaped cortically based hypodense area is noted in the interpolar region of the right kidney.

Discussion

Infective endocarditis is an infection of the endocardial surface of the heart, classically having vegetations on heart valves and causing systemic manifestations.  This disease has evolved throughout history with many new and varying causes.  Prior to antibiotics, rheumatic fever was the main cause of endocarditis. 5  With the advent of prosthetic heart valves and IV drug abuse, these have become more common causes.

The incidence of endocarditis in intravenous drug users is forty times that of the general population.  Damage to the valve is often caused mechanically by particulate matter such as talc that is mixed with the injected drug, as well as by drug-induced pulmonary hypertension, which causes turbulence. 6  While the tricuspid valve has the highest percentage of vegetations (40-70%), mitral and aortic valves also account for a significant number of cases (20-30%).  Bacterial load is also a significant risk factor in endocarditis.  Cocaine has a shorter half-life than heroin and therefore requires more frequent dosing and increases the bacterial load and therefore incidence of endocarditis. 6

Durack DT, et al proposed in 1994 new Duke Criteria for the diagnosis of infective endocarditis.

These criteria are as follows:
Clinical diagnosis requires the following:
Two major criteria or
One major and three minor criteria or
Five minor criteria

Major Criteria

  1. Positive Blood Cultures (of typical pathogens) from at least two separate cultures
  2. Evidence of endocardial involvement by echocardiography, such as the following:  endocardial vegetation, perivalvular abscess, new partial dehiscence of prosthetic valve, new valvular regurgitation

Minor Criteria

  1. Predisposition: Predisposing heart condition or IV drug use
  2. Fever: Greater than or equal to 38o C
  3. Vascular phenomena:  arterial emboli, septic pulmonary infarcts, mycotic aneurysm, conjunctival hemorrhages, or Janeway lesions
  4. Microbiologic evidence:  Single positive blood culture (except for coagulase negative staphylococcus, or an organism that does not cause endocarditis)
  5. Echocardiographic findings:  Consistent with endocarditis, but does not meet major criteria

The case presented meets the above mentioned criteria.  There were three blood cultures positive for Streptococcus Intermedius as well as a new aortic regurgitation murmur, thus fulfilling two major criteria.  In addition, this patient had a predisposition towards endocarditis since he was an intravenous drug user.  The documented vascular phenomena of renal and splenic infarcts from septic emboli further confirmed the diagnosis and gave the explanation of the initial presenting complaint of abdominal pain.

Infective endocarditis is an important consideration in the differential diagnosis for any intravenous drug abuser as it causes significant morbidity and mortality.  Although infarcts from septic emboli are a rare complication, it must be considered by emergency physicians in the differential diagnosis of abdominal pain in this patient population.

Reference

  1. Andreoli, Thomas E. et al. Infections of the Heart and Vessels. In: Cecil Essentials of Medicine. 5th ed. Philadelphia W.B. Saunders, 2001:798-804.

  2. Durack DT, Lukes AS, Bright DK. New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings: Duke Endocarditis Service, Am J Med, 1994; 96:200-209.

  3. Heiro M. Nikoskelainen J. Hartiala JJ. Saraste MK. Kotilainen PM. Diagnosis of Infective Endocarditis, Sensitivity of the Duke vs. von Reyn Criteria. Archives of Internal Medicine. 158: 18-24, 1998.

  4. Ma, O. John and Mateer, J. Cardiac. Emergency Ultrasound. McGraw Hill, 2003: Figure 5-78.

  5. Marx, John A. et al. Infective Endocarditis and Valvular Heart Disease. In: Rosen’s Emergency Medicine Concepts and Clinical Practice. 5th ed. St. Louis: Mosby, Inc., 2002: 1149-1157.

  6. Tintinalli, Judith E. et al. Injection Drug Users. Emergency Medicine, A Comprehensive Study Guide, 6th edition. McGraw-Hill, 2004:1893-1894.