A 22 years old lady complains of sore throat for 3 days along with fever and headache. On examination, she was severely dehydrated, her BP was found to be 90/50 mm Hg and on he distal aspect of the cuff, small red spots were noted. What could the the most probable etiological agent responsible for causing these symptoms?
Ans. d. Neisseria meningitides (Ref: Harrison 19/e p995, 18/e p1215; Ananthanarayan 7/e p222-223)N. meningitides (Meningococci)Gram (-)ve, aerobic, nonmotile, lens shaped diplococciQOxidase positiveQ (key test for identifying Neisseria)Can grow both intracellularly and extracellularlyCategorized as b-proteobacteriumQ on basis of genome sequencingClassification:On the basis of capsular polysaccharide, classified into 13 serogroups5 serogrops are responsible for most meningococcal diseases (A,B,C,W,Y)QGroup A- epidemic, Group B- both epidemic and outbreak, Group C- Localized outbreakQVirulence Factors:Capsular polysaccharideOuter membrane protein (pilli)Lipoligosaccharide, LOS (endotoxin)Q NOT the lipopolysaccharide: morbidity and mortality of meningococcal bacteremia and meningitis is directly proportional to amount of circulating meningococcal endotoxinCharacteristic Features:Deficiency of terminal or alternate complement pathway C5-C9Q increases the risk of meningococcal infectionMeningitis is the result of blood borne disseminationQ and not the direct invasion Early symptoms are non-specific and suggest an influenza like illness with fever, headache, and myalgia accompanied by vomiting and abdominal pain.Rash, if present may appear to be viral early in the course, until petechie or purpuric lesions develop.Fulminant meningococcemia. most rapid lethal form of septic shock, with prominent hemorrhagic skin lesions and characteristic rashQLab Diagnosis:Diagnosis is established by recovering meningococci from sterile body fluids such as blood, CSF etcGrow best on Muller-HintonQ or chocolate agar at 350C in 5-10% CO2.Thayer-martin media is selective mediaQ used for culturing throat or nasopharyngeal specimenTreatment:3rd generation cephalosporin such as cefotaxime or ceftriaxoneQ is DOC for initial therapyProphylaxis: Rifampicin is DOC for meningococcal prophylaxisQPrevention:Vaccine- Quadrivalent vaccine Meningococcal polysaccharide vaccine (serogroup A, C, W, Y)QThere is no vaccine against serogroup BQ as its capsule is non-immunogenicVaccine is ineffective in Age < 2 yearsQ, so given after 2 years.
Brucella abortus
Chlamydia trachomatis
Brucella suis
Neisseria meningitides
Neisseria