MI3.1-9 | Bloodstream & Cardiovascular Infections — Glossary

Normocytic normochromic anaemia in prolonged infection — caused by hepcidin-driven iron sequestration in macrophages, suppressed EPO, and shortened RBC survival

Hookworm endemic in India and South Asia; adult attaches to jejunum and ingests 0.15 mL blood/worm/day; more virulent than Necator americanus

Modified macrophage with 'caterpillar chromatin', found in Aschoff bodies in rheumatic fever

Antibody against streptococcal DNase B; more sensitive than ASO for confirming preceding GABHS infection, especially with skin strains

Antibody against streptolysin O produced by GABHS; elevated titre indicates recent streptococcal pharyngitis

Sudden, severe fall in haemoglobin in a patient with pre-existing haemolytic anaemia, caused by parvovirus B19 transiently halting erythropoiesis

Pathognomonic granuloma of rheumatic fever — perivascular, with central fibrinoid necrosis and Anitschkow cells

Antistreptolysin O titre — significant if >200 Todd units (adults) or >333 Todd units (children <5 years)

Automated continuous blood culture monitoring systems using CO₂ detection to signal positive bottles

Complication of severe P. falciparum malaria — massive intravascular haemolysis causing haemoglobinuria (dark urine) and acute renal failure

IE with repeatedly negative blood cultures — caused by prior antibiotics or fastidious organisms (Coxiella, Bartonella, Brucella)

Culture of bone marrow aspirate — gold standard for enteric fever diagnosis at ANY stage; 90% sensitivity even after antibiotic initiation

Individual who excretes S. Typhi in faeces/bile for >1 year; reservoir for typhoid; often associated with chronic cholecystitis; identified by Vi agglutination + stool cultures

Diagnostic criteria for IE: 2 major, or 1 major + 3 minor, or 5 minor criteria

Ineffective or disordered red cell production in the bone marrow, resulting in fewer functional RBCs entering the circulation

Systemic febrile illness caused by Salmonella Typhi (typhoid) or Paratyphi A/B/C, transmitted via faeco-oral route

Transmembrane iron exporter on enterocytes and macrophages; blocked by hepcidin in ACI, trapping iron within cells

Flagellar antigen of Salmonella; H antibodies persist for months to years — indicate past infection or immunisation

Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella — slow-growing Gram-negative rods causing 5–10% of IE; need extended incubation

Anaemia caused by premature destruction of red blood cells, characterised by elevated bilirubin, reticulocytosis, elevated LDH, and low haptoglobin

Liver-produced peptide hormone stimulated by IL-6; inhibits ferroportin, blocking iron export from intestinal enterocytes and macrophages

Ancylostoma duodenale and Necator americanus — intestinal nematodes that attach to jejunal mucosa and cause chronic blood loss leading to iron deficiency anaemia

Excessive destruction of blood cells by an enlarged spleen, causing pancytopenia — seen in kala-azar and other causes of splenomegaly

Microbial infection of the cardiac endothelium (usually valves) producing fibrin-platelet-organism vegetations

Microcytic hypochromic anaemia with low serum iron, low ferritin, high TIBC — commonest type of anaemia worldwide; commonest infective cause is hookworm

Non-tender haemorrhagic macule on palms/soles in IE — embolic in nature, associated with S. aureus

Diagnostic criteria for rheumatic fever — 2 major, or 1 major + 2 minor criteria, with evidence of preceding GABHS infection

International serotyping scheme for Salmonella based on somatic O antigens, flagellar H antigens, and Vi capsular antigen

Intracellular protozoan causing visceral leishmaniasis (kala-azar) — infects macrophages in bone marrow, liver, spleen; causes pancytopenia via hypersplenism and marrow infiltration

Specialised epithelial cells overlying Peyer's patches that transcytose antigens and pathogens into the lymphoid tissue — entry portal for S. Typhi

Multi-drug resistant Salmonella Typhi — resistant to chloramphenicol, ampicillin, and co-trimoxazole (the traditional first-line agents)

Cross-reactivity between microbial antigens (GABHS M-protein) and host tissue antigens (cardiac myosin, valve endothelium), driving autoimmune damage

Sterile platelet-fibrin thrombus on damaged endocardium — the nidus that allows bacterial colonisation in IE

Somatic lipopolysaccharide antigen of Gram-negative bacteria; O antibodies rise early and fall rapidly — indicate acute/recent infection

Painful nodule on finger pulps in IE — immune complex-mediated vasculitis

DNA virus that infects erythroid progenitors via globoside (P antigen) receptor; causes fifth disease in children and aplastic crisis in haemolytic anaemia patients

Lymphoid aggregates in the lamina propria of the terminal ileum; primary site of S. Typhi invasion via M-cells

Fever >38.3°C on several occasions, duration >3 weeks, no diagnosis after 1 week of thorough inpatient investigation (Petersdorf-Beeson definition)

Paradoxically slow pulse despite high fever in typhoid — caused by S. Typhi endotoxin affecting cardiac conduction; also called Faget's sign

Abnormally low reticulocyte count in the setting of anaemia, indicating failure of bone marrow to produce compensatory RBCs — suggests marrow suppression (parvovirus B19, HIV, kala-azar)

Non-suppurative, delayed inflammatory complication of pharyngeal GABHS infection, mediated by molecular mimicry

IE affecting the tricuspid valve, typically in IV drug users; caused by S. aureus; presents with septic pulmonary emboli rather than systemic emboli

Faint pink maculopapular lesions (2–4 mm) on the trunk in typhoid fever; represent microemboli of bacteria; appear in Week 2

Oval retinal haemorrhage with white centre in IE — immune complex deposition

Genomic regions in Salmonella encoding effector proteins that manipulate host cell biology — SPI-1 mediates invasion, SPI-2 enables intracellular survival

Gram-negative, facultative intracellular rod in group D of Kauffmann-White scheme (O:9,12; H:d; Vi antigen); sole reservoir is humans

Monthly benzathine penicillin injections given to prevent recurrent GABHS pharyngitis and further rheumatic valve damage

Enrichment broth that selectively inhibits coliforms while allowing Salmonella/Shigella to multiply; used before plating on selective media for stool culture

Life-threatening organ dysfunction caused by a dysregulated host response to infection (Sepsis-3 definition)

Linear subungual haemorrhage in IE — microemboli in nail bed capillaries

Involuntary, irregular movements caused by GABHS antibodies cross-reacting with basal ganglia — a major Jones criterion

Killed whole-cell vaccine against Typhoid, Paratyphoid A and B — stimulates H antibodies predominantly; confounds Widal H titre interpretation

Measure of transferrin's capacity to bind iron; elevated in iron deficiency anaemia (increased transferrin production), low/normal in ACI

Colorimetric assay detecting anti-O9 antibodies specific to S. Typhi; rapid alternative to Widal in endemic areas

Detects IgM antibodies against 50 kDa outer membrane protein of S. Typhi; IgM-specific test reduces false positives from residual IgG in endemic populations

Friable mass of fibrin, platelets, red cells, and microorganisms on the valve leaflet in IE

Polysaccharide virulence capsule of S. Typhi that inhibits phagocytosis and complement activation; marker for carrier detection (Vi agglutination)

Alpha-haemolytic oral streptococci (S. sanguinis, S. mutans, etc.) — commonest cause of subacute IE on damaged valves

Tube or slide agglutination test detecting antibodies against O and H antigens of Salmonella; most useful in Week 3 of illness using paired sera

Highly selective medium for S. Typhi — colonies appear black with metallic sheen due to H₂S production in iron-containing medium

Extensively drug resistant Salmonella Typhi — additionally resistant to fluoroquinolones and 3rd-generation cephalosporins; only azithromycin/carbapenems effective