V. A. Bacterial Diseases

Transcription

1 V. A. Bacterial Diseases A. Airborne Bacterial Diseases B. Foodborne & Waterborne Bacterial Diseases C. Soilborne Bacterial Diseases D. Arthropodborne Bacterial Diseases E. Sexually Transmitted Bacterial Diseases F. Miscellaneous Bacterial Diseases

2 V. A. Airborne Bacterial Diseases 1. Streptococcal Diseases 2. Diphtheria 3. Pertussis 4. Meningococcal Infections 5. Haemophilus influenzae Infections 6. Tuberculosis 7. Pneumococcal Pneumonia 8. Primary Atypical Pneumonia 9. Legionellosis

3 V. A. 1. Streptococcal Diseases Properties of the Genus Streptococcus General Properties Gram-positive Cocci in Chains or Pairs Catalase Negative Back to Airborne

4 V. A. 1. Streptococcal Diseases Properties of the Genus Streptococcus (cont.) Hemolytic Reactions Detected by Blood Agar Cultures Beta Hemolysis Complete Hemolysis Clear Zone Around Colonies on Blood Agar Alpha Hemolysis Incomplete Hemolysis Greenish Zone Around Colonies on Blood Agar Gamma Reaction Absence of a Hemolytic Reaction No Change Around Colonies on Blood Agar Back to Airborne

5 V. A. 1. Streptococcal Diseases Properties of the Genus Streptococcus (cont.) Lancefield Groups Based on Serological Groupings Also may be distinguished by Biochemical Testing or Antibiotic Sensitivity Group A Streptococcus pyogenes The most virulent human pathogen of the genus Beta hemolytic Often identified by rapid serological tests or by antibiotic resistance Back to Airborne

6 V. A. 1. Streptococcal Diseases Properties of the Genus Streptococcus (cont.) Lancefield Groups (cont.) Group B Streptococcus agalactiae Mildly to moderately virulent; esp. in children & elderly Usually beta or alpha hemolytic; some strains are gamma Detected biochemically Back to Airborne

7 V. A. 1. Streptococcal Diseases Properties of the Genus Streptococcus (cont.) Lancefield Groups (cont.) Group D Includes the fecal streptococci (enterococci) Normal colon flora in humans & other animals Genus Enterococcus Several species; eg. Enterococcus faecalis Occasionally pathogenic; often in urinary tract infections Usually gamma reactive Detected biochemically Back to Airborne

8 V. A. 1. Streptococcal Diseases Diseases Associated with Streptococcus pyogenes Respiratory Symptoms Upper Respiratory Tract Pharyngitis Systemic Symptoms Septicemia Internal infections Scarlet fever Due to strains that produce an erythrogenic toxin Back to Airborne

9 V. A. 1. Streptococcal Diseases Diseases Associated with Streptococcus pyogenes (cont.) Immune-Related Complications Rheumatic fever Glomerulonephritis Other Conditions/Portals of Entry Erysipelas Necrotizing fasciitis Puerperal sepsis Back to Airborne

10 V. A. 2. Diphtheria Cause: Corynebacterium diphtheriae Properties of the Genus Corynebacterium Gram-positive rods; non-sporeforming Coryneform (diphtheroid) arrangement Snapping division Metachromatic Granules Several different species Frequently found in soil & in the skin flora Only virulent strains of Corynebacterium diphtheriae are considered pathogenic Back to Airborne

11 V. A. 2. Diphtheria Cause: Corynebacterium diphtheriae Properties of Corynebacterium diphtheriae Virulent strains contain a extra gene that encodes for the diphtheria exotoxin The exotoxin is a cytotoxin that inhibits protein synthesis -- kills host cells Back to Airborne

12 V. A. 2. Diphtheria Transmission & Symptoms Airborne; contact with infected persons Upper Respiratory Infection Pseudomembrane Formation May Spread into Bloodstream Cardiovascular damage Vaccination with diphtheria toxoid vaccine Back to Airborne

13 V. A. 3. Pertussis Cause: Bordetella pertussis Gram-negative aerobic rod Found among the respiratory flora of humans & other animals Transmission and Symptoms Airborne contact with infected persons Upper respiratory tract infection; may be severe in children & elderly Difficulty breathing; staccato cough ( whooping cough ) Usually does not spread into bloodstream Back to Airborne

14 V. A. 4. Meningococcal Infections Cause: Neiserria meningitidis Properties of the Genus Neiserria Gram-negative cocci in pairs Several species; some of which are normal colon flora Fastidious nutritional requirements Grow best on chocolate agar Notable pathogenic species Neiserria meningitidis Neiserria gonorrhoeae Back to Airborne

15 V. A. 4. Meningococcal Infections Transmission & Symptoms Airborne contact with infected persons Often associated with children & with persons in close or crowded quarters eg. schools, daycare, etc. Upper respiratory tract symptoms Septicemia Meningitis Headache and stiff neck Listlessness; dizziness; disorientation Seizures; coma; death Back to Airborne

16 V. A. 5. Haemophilus influenzae Infections Cause: Haemophilus influenzae Properties of the genus Haemophilus Gram-negative rod Facultatively anaerobic Fastidious -- requires chocolate agar for growth Several species; common among the respiratory flora Back to Airborne

17 V. A. 5. Haemophilus influenzae Infections Cause: Haemophilus influenzae (cont.) Notable species Haemophilus influenzae: Several strains; common in the upper respiratory tract. Type b is associated with some cases of bacterial meningitis; type III is sometimes the cause of certain eye infections Haemophilus ducreyii: Causative agent of chanchroid Back to Airborne

18 V. A. 5. Haemophilus influenzae Infections Transmission & Symptoms Infections most frequently associated with the virulent strain, type b Upper respiratory tract symptoms Rhinitis and Sinusitis Otitis media Epiglottitis Septicemia and Meningitis Prevented by HIB vaccine Back to Airborne

19 V. A. 6. Tuberculosis Cause: Mycobacterium tuberculosis Properties of the genus Mycobacterium Acid-fast rods Grow slowly; some species are difficult to culture Several species; some found in soil and among skin flora Major pathogenic species: Mycobacterium tuberculosis Mycobacterium avium-intracellulare Mycobacterium cheloni Mycobacterium scrofulaceum Mycobacterium leprae Back to Airborne

20 V. A. 6. Tuberculosis Transmission & Symptoms Transmission Airborne Contact Prolonged Exposure Occasionally via skin contact or wounds Back to Airborne

21 V. A. 6. Tuberculosis Transmission & Symptoms (cont.) Symptoms Lung Infection Destruction of alveoli Cough; sputum Tubercle Formation May remain dormant for years and then become active again May spread to other areas of the body: Miliary TB Back to Airborne

22 V. A. 6. Tuberculosis Transmission & Symptoms (cont.) Detection: Microscopic examination Chest X-Ray Culture Tuberculin Skin Test TB Vaccination Back to Airborne

23 V. A. 7. Pneumococcal Pneumonia Cause: Streptococcus pneumoniae Properties of the Genus -- See Earlier Notes Formerly Known as Diplococcus pneumoniae No Lancefield classification Gram-positive diplococci; virulent strains are encapsulated Alpha Hemolytic A common cause of secondary bacterial pneumonia Back to Airborne

24 V. A. 7. Pneumococcal Pneumonia Transmission & Symptoms A frequent cause of secondary bacterial pneumonia Airborne transmission Lower Respiratory Tract Infection Pneumonia Fluid Buildup in Lung Back to Airborne

25 V. A. 8. Primary Atypical Pneumonia Cause: Mycoplasma pneumoniae Properties of the Genus Mycoplasma Small, irregular cells Naturally cell wall deficient Several species Common among respiratory flora in humans & other animals Back to Airborne

26 V. A. 8. Primary Atypical Pneumonia Transmission & Symptoms Airborne Transmission May be opportunistic Frequently causes mild cases of primary pneumonia Mycoplasma pneumoniae may also cause severe secondary pneumonia in immunocompromised patients Back to Airborne

27 V. A. 9. Legionellosis Cause: Legionella pneumophila Properties of the genus Legionella Gram-negative rods Strictly aerobic Found in highly aerated, moist environments eg. streams May parasitize certain aquatic protozoa Can contaminate building ventilation systems, air filters, etc. Back to Airborne

28 V. A. 9. Legionellosis Transmission & Symptoms Airborne Contact with infected persons or environments Mild to Moderate Pneumonia Back to Airborne

29 V. B. Foodborne & Waterborne Bacterial Diseases 1. Foodborne Intoxications vs Infections 2. Botulism 3. Staphylococcal Food Poisoning 4. Clostridial Food Poisoning 5. Typhoid Fever 6. Salmonellosis 7. Shigellosis 8. Cholera 9. Diseases associated with Escherichia coli 10. Camphylobacteriosis and Helicobacteriosis

30 V. B. 1. Foodborne Intoxications vs Infections Foodborne intoxications: Caused by the exotoxin secreted by bacteria in contaminated food Foodborne infections: Caused by the ingestion of live bacteria that colonize the digestive tract Back to Food- and Waterborne

31 V. B. 2. Botulism Cause: Clostridium botulinum Properties of the genus Clostridium Gram-positive rod Strictly anaerobic Spore-former Widely distributed, especially in soil Important species: Clostridium botulinum Clostridium perfringins Clostridium tetani Back to Food- and Waterborne

32 V. B. 2. Botulism Transmission & Symptoms Transmitted via contaminated food Botulinum toxin: A neurotoxic exotoxin Heat sensitive Inhibits synaptic transmission at motor neuron end plates Causes flaccid paralysis Very deadly: Death due to respiratory & cardiac failure Treatment: Administration of antitoxin Back to Food- and Waterborne

33 V. B. 2. Botulism Transmission & Symptoms (cont.) Other mechanisms of transmission: Wound botulism Animal botulism Infant botulism Back to Food- and Waterborne

34 V. B. 3. Staphylococcal Food Poisoning Cause: Staphylococcus aureus Properties of the genus Staphylococcus Gram positive coccus in clusters Catalase positive Two major species Staph. aureus is more virulent & is coagulase positive Staph epidermidis is more common & is coagulase negative Both are common skin & upper RT flora Back to Food- and Waterborne

35 V. B. 3. Staphylococcal Food Poisoning Transmission & Symptoms Certain strains of Staph. aureus: Produce staphylococcal enterotoxin Toxin is secreted in contaminated food Causes abdominal pain, nausea, diarrhea, for a few hours Staph. aureus enterotoxin is unusually heat-resistant Back to Food- and Waterborne

36 V. B. 4. Clostridial Food Poisoning Cause: Clostridium perfringins Certain strains secrete an enterotoxic exotoxin Transmission & Symptoms Similar to staphylococcal food poisoning, except that the clostridial enterotoxin is not as heat-stable Back to Food- and Waterborne

37 V. B. 5. Typhoid Fever Cause: Salmonella typhi Properties of the genus Salmonella A member of the family Enterobacteriaceae Colon flora; sometimes carried asymptomatically Gram negative rods Facultatively anaerobic Salmonella typhi Most virulent member of the genus Back to Food- and Waterborne

38 V. B. 5. Typhoid Fever Transmission & Symptoms Transmission via oral route often associated with contact with infected persons, either symptomatic or carriers sewage flies Back to Food- and Waterborne

39 V. B. 5. Typhoid Fever Transmission & Symptoms Invades intestinal epithelium tissue ulceration bloody stools but little diarrhea Blood invasion fever; delirium blood vessel hemorrhaging rose-colored spots on the abdomen bowel perforation gall-bladder infection Back to Food- and Waterborne

40 V. B. 6. Salmonellosis Cause: Salmonella serotypes Serotypes of the genus Salmonella other than S. typhi Hundreds of serotypes; species names exist but are often not reported Examples Salmonella enteriditis Salmonella gallinarum Salmonella typhimurum Back to Food- and Waterborne

41 V. B. 6. Salmonellosis Transmission & Symptoms Contaminated food Meat Poultry products Dairy products Gastroenteritis Cramps Nausea Vomiting Diarrhea Back to Food- and Waterborne

42 V. B. 7. Shigellosis Cause: Shigella species Genus Shigella Species A member of the family Enterobacteriaceae Colon flora; sometimes carried asymptomatically Gram negative rods Facultatively anaerobic Shigella sonnei Shigella dysenteriae Shigella flexneri Shigella boydii Back to Food- and Waterborne

43 V. B. 7. Shigellosis Transmission & Symptoms Transmission: Similar to salmonellosis Gastroenteritis Often with watery diarrhea Sometimes with bloody stools: Dysentery Back to Food- and Waterborne

44 V. B. 8. Cholera Cause: Vibrio cholerae Genus Vibrio Gram-negative curved bacteria comma-shaped facultatively anaerobic Normal flora in many animals Notable Pathogenic Species Vibrio cholerae Vibrio parahaemolyticus Back to Food- and Waterborne

45 V. B. 8. Cholera Transmission & Symptoms Transmission: Contaminated food shellfish vermin livestock Back to Food- and Waterborne

46 V. B. 8. Cholera Transmission & Symptoms (cont.) Gastroenteritis with extensive severe diarrhea Cholera enterotoxin Toxin blocks water reabsorption by inhibiting the anion active transport mechanism in large intestinal epithelium Rice water stools Dehydration & death Recent epidemic due to spread of new drugresistant strain Back to Food- and Waterborne

47 V. B. 9. Diseases associated with Escherichia coli Cause: Escherichia coli Family Enterobacteriaceae Gram-negative rods Facultatively anaerobic Widely distributed among humans & animals Normal colon flora Used as indicator of water & food contamination Back to Food- and Waterborne

48 V. B. 9. Diseases associated with Escherichia coli Transmission & Symptoms Oral route Extremely common normal flora Different strains in different geographical regions Colonize gut in infancy Infantile diarrhea Traveler's diarrhea Back to Food- and Waterborne

49 V. B. 9. Diseases associated with Escherichia coli Transmission & Symptoms (cont.) E. coli strain O157:H7 A rare, particular virulent & deadly strain Hemorrhagic E. coli disease Kidney damage in children Back to Food- and Waterborne

50 V. B. 10. Camphylobacteriosis and Helicobacteriosis Camphylobacter jejuni Gram-negative spirillum Microaerophilic Normal flora of colon Common cause of mild to moderate gastroenteritis Back to Food- and Waterborne

51 V. B. 10. Camphylobacteriosis and Helicobacteriosis Helicobacter pylori Gram-negative spirillum Microaerophilic Can colonize the stomach lining underneath the protective mucous layer Stomach irritation and ulcers Back to Food- and Waterborne

52 V. C. Soilborne Bacterial Diseases 1. Anthrax 2. Tetanus 3. Gas Gangrene 4. Leptospirosis 5. Listeriosis

53 V. C. 1. Anthrax Cause: Bacillus anthracis Genus Bacillus Gram-positive rods Facultatively anaerobic Spore-forming Widely distributed in soil Many species; Bacillus anthracis is the most important human pathogen of the group Back to Soilborne

54 V. C. 1. Anthrax Transmission & Symptoms Transmission Contact with contaminated soil Livestock Through skin; wounds; abrasions Also through oral route or airborne Skin anthrax Intestinal anthrax Pulmonary anthrax; Woolsorter s disease Back to Soilborne

55 V. C. 2. Tetanus Cause: Clostridium tetani Genus properties: See Botulism Transmission & Symptoms Wounds; esp. deep or puncture wounds Tetanospasmin: A neurotoxic exotoxin Acts as a cholinesterase inhibitor Short-circuits nerve synapses; esp. in the central nervous system Causes rigid paralysis Treatment: Antitoxins plus muscle relaxants Prevention: Vaccination with tetanus toxoid Back to Soilborne

56 V. C. 3. Gas Gangrene Often caused by Clostridium perfringins Genus properties: See Botulism Transmission & Symptoms Wounds; esp. deep wounds Gangrene: Tissue death due to reduced oxygen to tissue Gas or moist gangrene: Gangrene accompanied by bacterial infection Swelling; tissue death; blackish discoloration Back to Soilborne

57 V. C. 4. Leptospirosis Cause: Leptospira interrogans A spirochete Found in soil contaminated with animal waste Transmission & Symptoms Contact with contaminated soil or animals Often enters through the feet Spreads to several organs, including liver, kidney, meninges Jaundice may be present May have bloody vomit Back to Soilborne

58 V. C. 5. Listeriosis Cause: Listeria monocytogenes Genus Listeria Small Gram-positive rods Non-sporeforming Found in soil; esp in soil contaminated with animal waste Back to Soilborne

59 V. C. 5. Listeriosis Transmission & Symptoms Contact with contaminated soil Also possibly transmitted via contaminated food Listeric meningitis Blood infection with high white count Uterine infections; miscarriage or congenital damage Back to Soilborne

60 V. D. Arthropodborne Bacterial Diseases 1. Plague 2. Lyme Disease 3. Rocky Mt. Spotted Fever 4. Epidemic Typhus 5. Endemic Typhus

61 V. D. 1. Plague Cause: Yersinia pestis Gram-negative, facultatively anaerobic rods in Family Enterobactereaceae; however, not normally found in colon Characterized by bipolar staining Back to Arthropodborne

62 V. D. 1. Plague Transmission & Symptoms Vector: Fleas, esp. rodent fleas Bubonic plague: Infection of lymph node tissue; swelling; hemorrhaging; buboes Septicemic plague Pneumonic plague Cases of airborne transmission among humans have been noted Back to Arthropodborne

63 V. D. 2. Lyme Disease Cause: Borrelia burgdorferi A spirochete Transmitted by deer ticks First noted in Northeastern US Back to Arthropodborne

64 V. D. 2. Lyme Disease Transmission & Symptoms Vector: Ticks of the genus Ixodes (deer ticks); may be transmitted by both immature & mature ticks Incubation period of several weeks Initial symptoms Flu-like symptoms Rash: Erythema chronicum migrans (ECM) Several weeks/months later Joint pain/swelling Arthritis-like symptoms Cardiovascular & nervous system damage Back to Arthropodborne

65 V. D. 3. Rocky Mt. Spotted Fever Cause: Rickettsia rickettsii A rickettsia: Small, gram-negative bacterium Obligately intracellular parasite Detected by serological testing, eg. the Weil-Felix test (Reaction of serum to Proteus OX19) Transmission & Symptoms Vector: Ticks Macropapipular rash begins on palms & soles then spreads to other parts of the body High fever & other flu-like symptoms Back to Arthropodborne

66 V. D. 4. Epidemic Typhus Cause: Rickettsia prowasekii Genus properties: See Rocky Mt. Spotted Fever Transmission & Symptoms Vector: Human Louse Epidemics; often in areas with reduced sanitation High fever; high fatality rate Rash begins on trunk of body & spreads to extremities Back to Arthropodborne

67 V. D. 5. Endemic Typhus Cause: Rickettsia typhi Genus properties: See Rocky Mt. Spotted Fever Transmission & Symptoms Vector: Fleas; esp. rodent fleas Endemic in many areas Often with mild or no symptoms Back to Arthropodborne

68 V. E. Sexually Transmitted Bacterial Diseases 1. Syphilis 2. Gonorrhea 3. Chlamydia 4. Chanchroid

69 V. E. 1. Syphilis Cause: Treponema pallidum A spirochete Cannot be cultured on lab medium Detected microscopically or serologically Back to STD

70 V. E. 1. Syphilis Transmission & Symptoms Transmission: Sexual contact or congenitally Primary Syphilis Few days after contact Hard Chancre Secondary Syphilis Several weeks after chancre disappears Fever; flu-like symptoms Rash Back to STD

71 V. E. 1. Syphilis Transmission & Symptoms (cont.) Tertiary Syphilis Months or years later Gummae: Lesions on skin & mucous membranes Damage to internal organs Cardiovascular & central nervous system damage Back to STD

72 V. E. 2. Gonorrhea Cause: Neiserria gonorrhoeae Genus Properties: See Neiserria meningitidis Transmission & Symptoms Transmission: Sexual contact or congenital Urinary Tract Symptoms Urethritis: Burning sensation; discharge Cystitis; kidney infection Male Reproductive Tract Symptoms Prostatitis Inflammation of epididymis & testes; sometimes sterility Back to STD

73 V. E. 2. Gonorrhea Transmission & Symptoms (cont.) Female Reproductive Tract Symptoms Uterine Infections Fallopian Tube inflammation; blockage; occasional sterility Pelvic Inflammatory Disease Other Infections Gonococcal Eye Infections Respiratory Tract Infections Back to STD

74 V. E. 3. Chlamydia Cause: Chlamydia trachomatis Genus Properties A small, Gram-negative bacterium Obligately intracellular parasite; similar to Rickettsia Occasionally carried subclinically as part of the normal vaginal flora Back to STD

75 V. E. 3. Chlamydia Transmission & Symptoms Very similar to gonorrhea: Often mistaken for gonorrhea Important to distinguish because the treatment is different from gonorrhea Identified by serological testing Transmission: Sexual contact or congenital Urinary and Reproductive Tract Symptoms Respiratory Tract and Eye Infections Back to STD

76 V. E. 4. Chanchroid Cause: Haemophilus ducreyii Genus Properties: See Haemophilus influenzae Haemophilus ducreyii is occasionally found among the vaginal flora or under the prepuce in males Transmission & Symptoms Transmission: Sexual contact Symptoms Painful soft chancre; sometimes mistaken for syphilis Urethritis; occasional pelvic inflammation Back to STD

77 V. F. Miscellaneous Bacterial Diseases 1. Leprosy 2. Staphylococcal Infections 3. Pseudomonas aeruginosa Infections

78 V. F. 1. Leprosy Cause: Mycobacterium leprae Genus Properties: See Tuberculosis Cannot be cultured; detected by skin biopsy Transmission & Symptoms Skin contact; not particularly contagious Whitish skin lesions Loss of sensation due to nerve damage Disfiguration Back to Miscellaneous

79 V. F. 2. Staphylococcal Infections Cause: Staphylococcus aureus Genus Properties: See Staph. Food Poisoning Transmission & Symptoms Skin contact; opportunistic Skin Infections Acne; boils; pimples Abscesses; carbuncles Impetigo Scalded Skin Syndrome Toxic Shock Syndrome Septicemia & High fever Back to Miscellaneous

80 V. F. 3. Pseudomonas aeruginosa Infections Cause: Pseudomonas aeruginosa Genus Pseudomonas Gram-negative rods Nonfermentative metabolism Most species are strictly aerobic Widely distributed in aquatic & moist soil environments Can contaminate moist aerated surfaces: water faucets; respiration equipment Back to Miscellaneous

81 V. F. 3. Pseudomonas aeruginosa Infections Transmission & Symptoms Frequently an opportunistic or a nosocomial infection Respiratory tract infections Urinary tract infections Infections in burn patients Back to Miscellaneous