Assist Prof Microbiology College of Medicine, Majmaah University TETANUS Assist Prof Microbiology College of Medicine, Majmaah University

LEARNING OBJECTIVES Explain etiology, pathogenesis and mechanism of transmission Discuss the mechanism of action of tetanus toxin Discuss the role of immunization in primary and secondary prevention of tetanus

TETANUS-ETIOLOGY Tetanus is caused by Clostridium tetani Gram positive anaerobic bacillus One of two genera that form spores Two forms: vegetative form and spore form Vegetative form: actively secretes toxin and cause disease Spore form: Dormant and metabolically inert, important in disease transmission

TETANUS-ETIOLOGY Spores present in soil, dust, manure, dirty metallic objects e.g. nails, sharp rusted metallic objects, wood pieces, etc. Spores excreted in feces of horse, sheep, chicken and other animals Soil mixed with feces-spores remain in soil for long time Non communicable disease

VIDEO TETANUS INTRODUCTION

TETANUS-TRANSMISSION Non invasive disease C. tetani remains localized to devitalized tissue Spores (& not Vegetative form) are important in disease transmission Spores enter body through cuts, lacerations, deep wounds, puncture wound etc. Neonatal tetanus-contaminated equipments to cut umbilical cord African nation-ritual of putting animal dung on umbilical stump

TETANUS-TRANSMISSION The spore can get into the body through broken skin -injuries from contaminated objects. Breaks in skin more likely to get infected Wounds contaminated with dirt, feces, spit (saliva) Puncture wounds- nail, needle, thorn Burns Crush injuries Injuries with dead tissue Rare ways of transmission Clean superficial wounds, surgical procedures, insect/ animal bites, compound fractures, I/V drug users

TETANUS-PATHOGENESIS Incubation Period- 3-21 days(1day-several months) Average IP 10 days Spores carried deep inside wound Anaerobic atmosphere: dead tissue, deep in tissue, foreign body, co-infection with aerobic organisms Spores germinate into vegetative form

TETANUS-PATHOGENESIS Vegetative form remain localized to wound Secrete toxin Tetanospasmin Active fragment binds to pre-synaptic motor neurons Retrograde axonal transport- to spinal cord and brain stem Toxin diffuses to inhibitory cells-Glycinergic and GABAergic neurons Toxin degrades Synaptobrevin-docking protein of pre-synaptic vesicles

TETANUS-PATHOGENESIS Release of inhibitory neurotransmitters Glycine & GABA is blocked Uninhibited spastic contraction of muscles Hyper-reflexia, spastic paralysis of muscles Lock jaw, trismus, neck stiffness, difficulty swallowing Opisthotonus

NEUROTRANSMISSION VIDEO

TETANUS-PATHOGENESIS COMPLICATIONS Laryngospasm Fractures Hospital-acquired infections Pulmonary embolism Aspiration pneumonia Breathing difficulty, possibly leading to death (10-20% of cases are fatal especially very young and old)

VIDEO NEONATAL TETANUS

TETANUS PREVENTION PRIMARY PREVENTION PREGNANT LADIES NEWBORNS Tdap between 27 & 36 weeks NEWBORNS DTaP -2,3,4 months PRE-SCHOOL (3-5 years) DTaP booster ADULTS(13-18 years) Single Td booster ADULTS >19 Years not received Tdap & PERSON >65 Years-should get Tdap

TETANUS PREVENTION SECONDARY PREVENTION NOT IMMUNIZED OR INCOMPLETE FULLY IMMUNIZED IMMUNIZATION STATUS Active immunization with tetanus toxoid No immunization Minor wound Tetanus toxoid & TIG Tetanus Immunoglobulins (TIG) single dose Tetanus prone wound

TETANUS TREATMENT Wound debridement Antimicrobial therapy: Metronidazole preferred over Penicillin G Penicillin G -structurally similar to GABA and competitively antagonizes this neurotransmitter Management of clinical tetanus: Human tetanus immunolobulin (TIG) General supportive management e.g. airway management, physiotherapy etc. Spasmolytics

MCQ Tetanus Is caused by Clostridium botulinum Causative organism secretes toxin tetanolysin Has an average incubation period of 3 days Is not a contagious disease Vegetative form is important in disease transmission

MCQ A 21-years-young boy met RTA and sustained multiple deep penetrating wounds on body. He has never been vaccinated for any disease in his life. Regarding secondary prevention of tetanus for this man, which of the following vaccination protocol should be followed? Tetanus toxoid only Tetanus toxoid and TIG TIG only Neither Tetanus toxoid nor TIG

MCQ A 39-years-old lady is brought to ER with clinical diagnosis of tetanus after a penetrating wound sole 15 days back. Regarding management of tetanus, what should be line of action? Inquire about her immunization status of tetanus Give tetanus toxoid irrespective of her immune status Give her TIG as a management protocol Reassure the relative as she does not need any immunization at present

MCQ What causes the major symptoms of tetanus? Multiplication of the organisms at the site of infection Production of botulin toxin Super-infection due to antibiotic therapy Bacteria multiplying in the bloodstream Production of tetanospasmin