Hemolytic anemia and Bacillus cereus septicemia in a patient with thalassemia intermedia Dr Grace Lam April 2010

Thalassemia intermedia Splenectomy as a child Refused iron chelation therapy Cord compression due to extramedullary hematopoiesis Clinical admission x Ix of bilateral exudative pleural effusion

Developed fever, respiratory failure & shock Blood cultures Bacillus species, then –ve ETA Candida species Urine Legionella Ag –ve Mycoplasma Ab <10 Bilateral pleural fluid: not suggestive of empyema CT abd & pelvis: possible early liver abscess Leptospira IgM –ve Widal test <1:50

Intravascular haemolysis ↑ Plasma Hb 1900.4mg/L (<50) ↓ Haptoglobin <0.06 (0.36 - 1.95g/L) ↑ LDH 457 Direct antiglobulin test +ve Anti-IgG +ve Anti-C3d –ve Indirect antiglobulin test –ve Malaria –ve

Waived Treatment Continued to deteriorate despite treatment Tienam + Anidulafungin + Doxycycline Drainage of bilateral pleural effusion CVVH High dose vasopressor Continued to deteriorate despite treatment Δ Septicemia with background thalassemia Waived

Haemolytic anaemia Intravascular haemolysis RBCs lysed in circulation Released free Hb: Bound by serum haptoglobin Excreted by liver Filtered into urine Reabsorbed by renal tubules (Urine haemosiderin) Haemoglobinuria Extravascular haemolysis RBCs phagocytosed by macrophages in liver & spleen Hb broken down & recycled: Heme → Unconjugated bilirubin Conjugated in liver Excreted into GI tract as stercobilinogen

Haemolytic anaemia or normal

Intravascular haemolysis Mechanisms Mechanical trauma Prosthetic heart valves Microangiopathic HA (TTP, HUS, DIC, HELLP) March Complement fixation Autoimmune hemolytic anaemia - Cold Drugs (complement-fixing immune complex) e.g. quinine Paroxysmal nocturnal haemoglobinuria Transfusion reactions Toxic damage

Intravascular haemolysis Toxic damage Infections Clostridium perfringens Malaria Babesiosis Bacillus cereus Thermal injury Snake venom Severe G6PD deficiency

Intravascular haemolysis Possible cause of intravascular haemolysis in our patient: +ve Coombs test: Immune-mediated haemolytic anaemia Toxic damage by infection Microangiopathic haemolytic anaemia

Autoimmune haemolytic anaemia AIHA Warm Ab active at 37oC Usually IgG Anti-IgG +ve Lympho-proliferative disease (CLL, NHL) Autoimmune diseases (RF, SLE) Drugs (Methyldopa) Idiopathic (60%) Cold Ab active <30oC Complement-fixing IgM Anti-C3d +ve Lymphoma Mycoplasma, Infectious mononucleosis Paroxysmal cold haemoglobinuria AIHA causes extravascular hemolysis (in which the Ab-coated RBC membrane is removed bit by bit in the spleen). If the Ab fixed complement, it will result in intravascular hemolysis. Cold AIHA (also called cold aglutinin disease). Could also occur with influenza, rubella, measles, adenovirus and psittacosis infections. Donath-Landsteiner test: Biphasic hemolysin pattern in paroxysmal nocturnal hemoglobinuria. Occurs transiently in children as a result of viral infection, associated with syphillus, chronic form in older patients. ?IgG

Direct antiglobulin test Direct Coombs test Detects abnormal Ab attached to RBCs Patient’s RBCs incubated with anti-human antiserum: Antiserum: Anti-IgG or Anti-C3d (detects complement fixation) -ve = + +ve

Indirect antiglobulin test Indirect Coombs test Detects free Ab vs RBCs in serum Step 1: Incubate patient serum with normal group O RBCs Step 2: Perform direct antiglobulin test +ve

Coombs test interpretation Indirect antiglobulin test –ve Direct antiglobulin test +ve Anti-IgG +ve Anti-C3d –ve Warm AIHA Unlikely the cause of intravascular haemolysis without evidence of complement fixation

Coombs test interpretation Haematopathologist Strength of +ve Coombs test Rated on a 4-point scale in PYNEH: + weakest → ++++ strongest Ag-specificity test on red cell elucidate Specific red cell Ab: past transfusion Broad-spectrum Ab: AIHA Simple bystander as a result of past blood transfusions Check strength of the positive coombs test + Ag specificity test on red cell elucidate (specific RBC Ab as a result of past transfusion or broad-spectrum Ab in AIHA)

Bacillus cereus A gram +ve or gram-variable bacillus Produces toxins: Enterotoxin, Hemolysin, Phospholipase C & Emetic toxin Disease spectrum Food poisoning in Immunocompetent Opthalmitis: Post-traumatic, IV drug abuse Fulminant septicemia in Immunocompromised: MOF, massive intravascular hemolysis, rapid death

Bacillus cereus septicemia

Bacillus cereus septicemia β-lactamase producing Resistant to Penicillin & Cephalosporin Carbapenems or Vancomycin Progressive clinical course despite appropriate antibiotics ∵ Toxin production Bacillus circulans – 1 case report on endocarditis Microbiologist: Bacillus circulans (commercial kit) In 1 blood culture only Likely a contaminant

Microangiopathic haemolytic anaemia Deranged clotting Platelet DIC – Contribution to intravascular haemolysis

Conclusion Septicemia in thalassemic patient Intravascular haemolysis Contributed by DIC Positive Coomb’s test Bystander as a result of past blood transfusions