Infectious Diseases PDF

Infectious Diseases Dr. Mohamed Roshdi ,MD Associate Prof. Internal medicine  Learning Objectives Knowledge Relate pathophysiological basics and etiology of important infectious diseases Describe epidemiology, manifestations, complications and management of important infectious diseases...

Infectious Diseases Dr. Mohamed Roshdi ,MD Associate Prof. Internal medicine  Learning Objectives Knowledge Relate pathophysiological basics and etiology of important infectious diseases Describe epidemiology, manifestations, complications and management of important infectious diseases Skills Interpret clinical manifestations and investigations of important infectious diseases to formulate reasonable diagnosis. Apply evidence-based management plan for important infectious diseases Distinguish patients in emergency situations to formulate a comprehensive management plan; ensuring keeping patients in normal homeostasis Aetiological Classification: ❖ Bacterial:  Gram(+ve): streptococci, staphylococci  Gram(-ve): Klebsiella, pseudomonas, Haemophilus influenza  Anaerobic bacteria: bacteroids ❖ Mycobacterial: TB, Leprosy ❖ Spirochetal: syphilis, leptospirosis ❖ Rickettsia: typhus ❖ Chlamydia ❖ Viral: Dengue, influenza, HSV, HZV, CMV, EBV, Measles, mumps, rubella ❖ Protozoal: malaria, ameobiasis, Bilharziasis, giardiasis ❖ Fungal: candida albicans, Aspergillus Niger ❑ Normal body core temperature is 36.5 – 37.2 °c - Oral: 35.2 - 38.2 °c - Rectal: 34.4 - 37.8 °c - Axillary: 35.5 - 37 °c ❑ Fever (pyrexia): increase body temperature more than the upper limit of normal ❑Hyperpyrexia: increase body temperature > 40º c Types of Fever: ❖ Sustained fever: daily fluctuations of fever is less than 1º c ❖ Remittent fever: daily fluctuations of fever is more than 1º c ❖ Hectic fever: body temperature falls to normal level once or more during the day. ❖ Relapsing fever: days of fever intercepted by days of normal temperature  Typhoid Fever Aetiology: ❖ Causative organism: Salmonella typhi & paratyphi A & B ❖ Mode of infection: Feco-oral transmission. Clinical picture: ❖ Clinical manifestations : 1st week: Fever (step-ladder), Headache, Relative bradycardia, Constipation, Rash ( rose spots ) 2nd week: fever (continuous), tachycardia, diarrhea, splenomegaly (No rash) 3rd week: Convalescence begins ❖ Complications: intestinal bleeding , peritonitis, Meningitis , encephalitis, convulsions, pyelonephritis ❖ Investigations: CBC: Leucopenia with relative lymphocytosis. Widal test: It is +ve from 2nd week (prognostic rather than diagnostic) Culture: Blood culture is +ve in 1st week, Stool culture is +ve in 2nd week & Urine culture is +ve in 3rd week. (the best diagnostic investigation) ❖ Treatment: - Ciprofloxacin , Co-trimoxazole ( septrin ), ceftriaxone  BRUCELLOSIS (Malta fever, undulant fever ) Etiology: ❖ Causative organism: Brucella (melitenesis, abortus or suis) ❖ Mode of infection: contaminated milk or remnants of aborted animals Clinical picture : ❖ Bone & muscle pain, vomiting, constipation ❖ Relapsing fever: fever for 10 days then apyrexia for 10 days, then fever and so on. ❖ Hepatosplenomegaly & Lymph node enlargement. Complications : Relapse. Infective endocarditis Orchitis. Paraplegia due to transverse myelitis. Abortion. Investigations : ❖ CBC: Lymphocytosis ❖ Blood Culture: +ve during fever spike. ❖Serological tests: Brucella agglutination test. (the best diagnostic test) Treatment: doxycycline or rifampicin for 6 weeks  Acquired immunodeficiency syndrome (AIDS) ❖ Aetiology: Infection with human immunodeficiency virus (HIV). ❖ Modes of infection: parenteral, Sexual & vertical ❖ Pathogenesis: The virus infects T-Lymphocytes mainly & may inhibit B- lymphocytes → suppression of both cellular & humoral immunity. When the T-Lymphocytes fall below 200 cells / dl, the patient develops opportunistic diseases (infections & malignancy) ❖ Clinical picture: ❑ Asymptomatic: may last up to 10 years ❑ Acute HIV syndrome: fever, rigors, arthralgia & rash for 2 weeks ❑ Symptomatic syndromes: Generalized LN enlargement. Constitutional Disease: persistent fever, loss of weight, diarrhea. Neurological Disease: Encephalitis, Neuropathy, Myopathy. Opportunistic Infections: CMV, HSV, TB & Pneumocystis carinii pneumonia. Secondary Neoplasms: Kaposi sarcoma, Non-Hodgkin's lymphoma Investigations: HIV- antibodies: for screening, appear within 2 weeks of infection. HIV-RNA by PCR : the best diagnostic test Treatment: Anti-Retroviral (HAART) Zidovudine 600 mg / day orally.  FEVER OF UNKNOWN ORIGEN (FUO) Definition: Persistent elevation of body temperature over 38.5° C for 3 weeks without Specific diagnosis after at least one week of inpatient investigations. Causes: ❑ Infections: ❖ Bacterial: TB, infective endocarditis, Typhoid fever, Brucellosis, Lung abscess, Pyelonephritis ❖ Viral: EBV, CMV, HIV, Hepatitis ❖ Protozoa: Malaria, Ameobiasis ❑ Malignancy: Hematologic: Lymphoma, Leukemia Non hematologic: Hypernephroma, Hepatoma, Bronchogenic carcinoma ❑ Collagen disease: Rheumatic fever, PAN, SLE, RA ❑ Others: inflammatory bowel disease, hemolysis, cerebral hemorrhage ❑ Undiagnosed Investigations : ❖ Laboratory: ESR > 100: in TB , collagen, malignancy CBC: leukemia, lymphoma, anemia Liver , kidney function test. Serology: Widal test , ANA & Anti-Ds-DNA. Culture: blood, urine, stool, sputum, CSF ❖ Imaging: X-ray: chest , bone. U/S: Heart, Abdomen, Pelvis. ❖ Endoscopy: upper GIT & lower GIT. ❖ Biopsy: LN, Bone marrow ❖ Therapeutic tests: Metronidazole (amoeba), Chloroquine (malaria), Aspirin (RF)  Chronic infection of the lung caused by mycobacterium tuberculosis bacilli aerobic non motile bacillus - Immunocomprimised (by disease or drug): AIDS, DM, leukemia, steroids Night fever, sweating, loss of weight & appetite Of thick mucoid or mucopurulent coin shaped sputum  Apical cavities and fibrosis or fluffy cotton appearance Markedly elevated Staining by hrs Used in combination for long period of time : only INH & rifampicin Summary References 1. Step-up to medicine 5th edition. ISBN-13: 978-1975103613 2. Davidson’s Principles & Practice of Medicine 23rd edition ISBN-13: 978-0702070280 Thank You