Lecture №Infections of the central nervous and locomotor systems
Infections of the central nervous systemcaused by: trauma leading to breach of integuments ofC.N.S. via blood from infective focus.Meningitis inflammation of the membranes( meninges ) that cover the brain and spinalcord.Bacterial meningitis (pyogenic)More sever than viral type.Clinical features. Symptoms of sever headache,fever, vomiting, photophobia and convulsionsleading to unconsciousness.Signs of meningeal irritation ,i.e. neck andspinal stiffness, and kernig ‘s sign ( pain and
The common causative agents of bacterial meningitis Neisseria meningitidis - common in childrenand young adults. Haemophilus influenzae - meningitis mostlyseen in children between 1 months and 4 yearsold. Streptococcus pneumoniae – in old patients. Mycobacterium tuberculosis.Meningitis spread quickly in close householdcontacts.Avoiding overcrowding in living and workingconditions.Chemoprophylaxis with antibiotics e.g.
Rarely causing meningitis organisms:Listeria monocytogenes, Leptospira interrogansand Cryptococcus neoformans.Laboratory diagnosis:Examination of C.S.F (lumbar puncture).C.S.F centrifuged and the deposit Gram-stainedand cultured.Treatment: dictated by the causative organismand its sensivity; empirical therapy with two orthree antibiotic drugs is given immediately.
Viral meningitis (aseptic meningitis) Benign, self-limited, resolves in 1-2 weeks and requires only symptomatic treatment. The major route of entry are respiratory and gastrointestinal tracts and from these ports spread to C.N.S by direct migration via olfactory nerves or indirectly via blood.The major causes of viral meningitis ( aseptic meningitis) and/or encephalitis1. Mumps virus 2. Coxsackievirus3. Herpes simplex virus 4. Adenovirus5. Measles virus 6. Influenza virus7. Varicella-zoster virusSusceptible persons (the most affected) : Children
Encephalitis Infection of the brain substance and patientoften show signs and symptoms of meningitisand encephalitis at the same time. Occurs after childhood illness such asmeasles, chickenpox and rubella, and rarelyafter immunization with vaccines such aspertussis. Patients often die or have debilitatingsequelae. Very serious disease needs prompt andintravenous antiviral treatment.
Poliomyelitis Caused by poliovirus types 1-3. The port of entry – mouth and the virus multiply in lymphoid tissue of the pharynx and intestine. Then enters the blood stream and causes viraemia, spread into C.N.S and causes neurological disease. The disease is an influenza-like illness, with meningitis and encephalitis. In some, damage of the anterior horn cells of the spinal cord leads to: 1. respiratory failure. 2. or permanent lower neuron weakness and paralytic poliomyelitis. Two types of Polio
Cerebral abscess infection reach the brain through blood or bydirect extension of sinus infection caused byoral bacteria or, rarely, as complication of acuteor chronic dental infection. also flow traumatic injury to the maxillofacialregion. infection mostly polymicrobial (mixed) -streptococci, staphylococci, anaerobic cocciand coliforms. treatment is surgical.
Tetanus Clostridium tetani (drum-stick bacillus).After I.P. (5-15 days) exotoxins cause severpainful muscle spasm:masseter muscles - lockjawfacial muscles – risus sardonicus (facialgrimace)Extensor muscles - opisthotonos (arched body)PathogenesisContamination of wound with spores from dust,soil or rusty objects results in sporegermination and release of tetanospasmin andtetanolysin.The bacteria remain localized at the site ofinfection, but the exotoxins absorbed at themotor nerve endings, diffuse towards the
EpidemiologyMain source is animal faeces.Tetanus is commonly associated with deep penetrating wounds, but it can result from superficial abrasions e.g. thorn pricks.Infection of umbilical stump - neonatal tetanus.DiagnosisMainly clinical.Treatment1. Supportive: muscle relaxants, sedation and artificial ventilation.2. Antitoxin: I.V in large dose.3.Antibiotics: penicillin or tetracycline to prevent further toxin production.4. Debridement: excision and cleaning of the wound.
PreventionActive immunization with toxoid in childhood, duringthe first year of life and before school entry.
Prophylaxis of wounded patients If the patient is immune, a booster dose oftoxoid should be given if the primary course(or booster dose) was given more than 10 yearspreviously, and human antitetanusimmunoglobulin (ATS) should be given if thewound is dirty and more than 24 h old. If the patient non-immune, human antitetanusimmunoglobulin should be given, followed by afull course of tetanus toxoid by injection. Penicillin – to prevent tetanus and to avoidpyogenic infection. Booster doses of toxoid 10 years after primarycourse and again 10 years later maintain
Infection of the locomotor system (bones and joints)Natural defenses1. macrophages in synovial membranes of joints.2. mononuclear cells, complement and lysozyme of synovial fluid.Acute septic arthritisCan be caused by S. aureus, H. influenzae, S.pneumoniae and other streptococci, N. gonorrhoeaeand non-sporing anaerobes such as Bacteroids spp.Others infrequent agents are M.tuberculosis,
Acute septic arthritis may result from:1. Traumatic injury through the joint capsule.2. Haematogenous spread, usually as a complicationof septicaemia.3. Extension of osteomyelitis or spread of infectionfrom an adjacent septic focus.4. Infection of joint prosthesis. source of infectionfor artificial joints may patient, operating team ortheatre air.Clinical features:Limitation of movement, swelling, redness and
Reactive arthritis Acute arthritis mediated by immunologicalmechanism. Genetic predisposition present. Affecting one or more joints. Develops 1-4 weeks after infection of genital(post-sexual reactive arthritis) orgastrointestinal tract (post-dysenteric arthritis). Post-sexual reactive arthritis caused byChlamydia trachomatis and almost all patientsare men. Post-dysenteric arthritis follow infection withSalmonella, Shigella, Yersinia orCampylobacter.
OsteomyelitisAcute osteomyelitis• usually occurs in children under 10 years old.• mostly caused by S. aureus ; H. influenzae, S.pyogenes, S. pneumoniae, Salmonella,Brucella, and non-sporing anaerobes.Chronic osteomyelitis• common in adults.• mostly caused by S. aureus. Salmonella,Brucella, Mycobacterium tuberculosis.
Osteomyelitis of the jaws• uncommon due to high vascularity of the jaws,especially maxilla.• Predisposing factors such as bone diseasesuch as osteopetrosis, bone tumors andirradiation.Laboratory diagnosisBlood culture, culture of pus from the bonyfocus – pus obtained by needle aspiration or byopen surgery and by specimens from theinfective focus e.g. “ cold abscess ” pus intuberculosis.Treatment