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Pathology of Bacterial Infection”

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Pathology of Bacterial Infection” “Pathology of Bacterial Infection” นายแพทย ดร.ณตพล ศุภณัฐเศรษฐกุล ภาควิชาพยาธิวิทยา คณะแพทยศาสตร มหาวิทยาลัยนเรศวร 11 กรกฎาคม พ.ศ. 2555 TOPICS Introduction Bacterial pathogenesis Classification of bacterial diseases Diseases and pathology 1 Introduction - First observed by Antonie van Leeuwenhoek in 1676 by using a single-lens microscope “animalcules” - Bacteria are prokaryotes, have a cell membrane but lack of nuclear membrane. - Classification of bacteria - Morphology - Staining - Living environment - Biochemical method - Molecular method - Pathogenicity http://cellbiology.med.unsw.edu.au/units/images/Bacterial_morphology_diagram.png 2 Gram Postive cocci in cluster Gram staining Gram negative bacilli Acid-fast staining : - Ziehl-Neelsen stain - Kinyoun stain Acid fast bacilli (AFB) http://www.ihcworld.com/royellis/gallery/images/zn.jpg 3 Introduction Living environment : Aerobic, Anaerobic, Facultative anaerobic, Microaerophilic, Obligate intracellular Biochemical method : substrate, enzyme, product Molecular method : DNA, RNA, using PCR method Pathogenicity : เชื้อประจําถิ่น (normal flora), เชื้อกอโรค (pathogen) Bacterial Pathogenesis การติดเชื้อ (Infection) หมายถึง กระบวนการที่เชื้อโรค เขาไปเจริญเติบโตอยูในเนื้อเยื่อของ host - การติดเชื้อที่ไมปรากฎอาการ (Subclinical infection) - ระยะที่เกิดอาการของโรคติดเชื้อ (Clinical illness) - การติดเชื้อแบบไมแสดงอาการ หรือ แบบแอบแฝง (Latent infection) 4 ปจจัยที่เกี่ยวของกับการเกิดโรคติดเชื้อ Pathogenicity หมายถึง ความสามารถของเชื้อที่จะทํา ใหเกิดโรคใน host Virulence factors : Exotoxin, Endotoxin, Antiphagocytic factor (capsule), Enzyme (hyaluronidase, collagenase, deoxyribonuclease, hemolysin) Host factor : Immunity, Inflammation, stress, occupation, hereditary ปจจัยอื่นที่มีผลตอการติดเชื้อ : 1. Tissue affinity 2. Microbial adherence 3. Invasion of the host 4. Infective dose 5. Portal of entry 6. Communicability via mode of transmission (direct contact, airborne, foodborne and water borne, animal vector or zoonoses) 5 Classification of Bacterial Diseases Type of bacteria : Streptococcus, Neisseria, Mycobacterium etc. Host status : Childhood, Immunocompetent, Immunocompromised, Opportunistic, Nosocomial Organs and systems involved : CVS, STD, UTI Duration of infection : Acute, Chronic, Sub-acute Mode of transmission : Vector-borne, airborne 6 Bacterial infection Classification Pyogenic gram positive cocci Bacterial infections of childhood Sexually transmitted bacterial diseases Enteropathogenic bacterial diseases Clostridial infection Bacterial infection with animal reservoirs Bacterial infection with immunocompromised host Filamentous bacterial infection Mycobacterial infection Chlamydial infection Rickettsial infection Mycoplasma infection 7 Pyogenic gram positive cocci Staphylococcus Streptococcus Staphylococcus aureus - gram-positive cocci that form grapelike clusters and cause… - skin lesions (furuncles (boils), carbuncles, impetigo, and scalded skin syndrome) - abscess, pneumonia,endocarditis,osteomyelytis, food poisoning, toxic shock syndrome, sepsis 8 - is a major cause of infection of persons with severe burns and surgical wounds. - Virulence factors, which are controlled by an autoinducing peptide, include: * surface proteins involved in adherence to host cells * Anti-phagocytosis: polysaccharide capsule 9 * enzymes that degrade host proteins, phospho- lipid membrane involved in abscess formation * toxins that lyse host cells: Exotoxins - scalded skin syndrome Enterotoxins - food poisoning Endotoxin and toxic shock syndrome toxin – hypotension (shock) with multi-organ failure especially in a woman using tampon 10 SSSS Staphylococcus Streptococcus Species Streptococci are gram-positive cocci that grow in pairs or chains 11 Streptococcal infection 3 types according to hemolytic pattern on bloody agar: - hemolytic streptococci (incomplete hemolysis) eg. S. pneumoniae, S. viridans, S. mutans - hemolytic streptococci (complete hemolysis) eg. S. pyogenes (group A), S. agalactiae (group B) - hemolytic streptococci (non-hemolytic) eg. S. faecalis (group D) S. pneumoniae is the most important -hemolytic streptococcus and is the major cause of community-acquired pneumonia (lobar pneumonia) and meningitis in adults. S. viridans causes an infective bacterial endocarditis S. pyogenes (-hemolytic streptococcus gr. A) referred to as flesh eating bacteria – cause a rapidly progressive necrotizing fasciitis. 12 S. pyogenes also causes : Pharyngitis Scarlet fever (most common in children 3 -15 years old) Erysipelas (rapidly spreading erythematous cutaneous swelling skin lesion) Rheumatic fever Poststreptococcal glomerulonephritis Acute pharyngitis and tonsillitis Erysipelas 13 Scarlet fever strawberry tongue circumoral pallor Pathogenesis of RHD 14 Figure 11-20 Infective (bacterial) endocarditis. A, Endocarditis of mitral valve (subacute, caused by Streptococcus viridans). The large, friable vegetations are denoted by arrows. B, Acute endocarditis of congenitally bicuspid aortic valve (caused by Staphylococcus aureus) with extensive cuspal destruction and ring abscess (arrow). Downloaded from: StudentConsult (on 22 December 2009 03:19 AM) © 2005 Elsevier เชื้อที่เปนสาเหตุของ Bacterial meningitis Streptococcus pneumoniae 50% Neisseria meningitidis 25% Group B streptococci 15% Listeria monocytogenes 10% Haemophilus influenzae <10% (type b) From Harrison ed. 16th 15 Bacterial infection of Childhood Diphtheria Pertussis Haemophilus influenza infection Diphtheria - is caused by gram-positive rod with clubbed ends Corynebacterium diphtheriae and is prevented by immunization with a formalin-fixed toxoid in the DPT vaccine. 16 Tracheal colonization may lead to - Diphtheria toxin (exotoxin) - Mucosal erosion - Formation of a suffocating pharyngeal fibrinosuppurative exudate (pseudomembrane) obstruct airway - Toxin-mediated damage to the heart, nerves, liver, or kidneys Diphtheria 17 Whooping Cough (Pertussis) - is caused by the gram-negative coccobacillus Bordetella pertussis - Acute, highly communicable illness with violent coughing followed by a loud inspiratory “whoop” - Laryngotracheobronchitis may include mucosal erosion, hyperemia, and copious mucopurulent exudates - pertussis toxin (exotoxin) paralyzes the cilia, impair pulmonary defense Haemophilus influenzae - is a gram-negative coccobacilli, which is a major cause of life-threatening epiglottitis, laryngotracheobronchitis, pneumonia and meningitis in young children. 18 Sexually Transmitted Diseases (STDs) Gonorrhea Chancroid Syphilis Neisseria gonorrhoeae - is an encapsulated, gram-negative diplococcus that causes urethritis, pharyngitis, or proctitis, depending on sexual practices. - Cause arthritis in reproductive age - may cause urethral strictures and chronic infections of the epididymis, prostate, and seminal vesicles. 19 - may infect the fallopian tubes (salpingitis), resulting in tubo-ovarian abscesses and scars, sterility, and ectopic pregnancy. - Perinatal ophthalmic infection was a major cause of blindness before prophylactic administration of silver nitrate to neonates became routine. 20 Chancroid (soft chancre) Haemophilus ducreyi (gram negative bacilli) Clinical feature: - Painful multiple genital ulcer and dirty-based ulcer - 50% inguinal lymphadenitis 21 Chancroid (soft chancre) Treponema pallidum (Syphilis) - is a microaerophilic spirochete with an axial periplasmic flagella wound around a slender, helical protoplasm, all of which is covered by an outer membrane. 22 -Primary syphilis: occurs approximately 3 weeks after contact with an infected individual, features a single firm, non-tender, raised, red lesion (chancre) located at the site of treponemal invasion on the penis, cervix, vaginal wall, or anus. - Secondary syphilis: occurs 2 to 10 weeks after the primary chancre, is characterized by a diffuse rash, particularly of the palms and soles, that may be accompanied by white oral lesions, fever, lymphadenopathy, headache, arthritis. 23 24 - Tertiary syphilis: occurs years after the primary lesion, is characterized by 1. Active inflammatory lesions of the aorta, heart (syphilitic aortitis with aneurysm), and central nervous system (neurosyphilis with paralysis and seizure) 2. Quiescent lesions (gummas) involving the liver, bones, brain and skin ลักษณะรอยโรคเปนจุดขาว และนิ่ม เรียกวา gummas - Congenital syphilis : Trans-placental to fetus 25 Tertiary syphilis syphilitic aortitis with aneurysm Enteropathogenic Bacterial infection Salmonella Shigella Cholera E. coli 26 SALMONELLA SPECIES S. enteritidis - contaminated chicken and beef are important causes of food poisoning. S. typhi, gram negative bacilli, is spread from person-to-person via the fecal-oral route, causes Typhoid fever (systemic infectious disease) Salmonella typhi (Typhoid fever) - septicemia, fever, abdominal pain - bacterial replication in macrophages of Peyer patches of terminal ileum nodule - ulcer along the intestine mucous bloody diarrhea shock 27 Shigella ทําใหเกิดกลุมอาการ “บิด” (Dysentery) : cramping, tenemus, mucus bloody diarrhea Shigella boydii, S. flexneri, S. dysenteriae Shiga toxin Fecal – oral route VIBRIO CHOLERAE - Gram negative, comma shape with flagella - is a non-invasive, toxin- producing bacteria that causes severe watery diarrhea - Cholera toxin increase levels of intracellular cAMP, and cause massive secretion of chloride, sodium, and water. 28 Mechanism of cholera Escherichia coli Gram negative bacilli Normal flora in lower intestines (colon) Cause several intestinal and extra-intestinal
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