CONTROL OF MICROBES

1. CONTROL OF MICROBES

2. Microbicidal agents kill microbes Microbistatic agents inhibit microbes. Germicidal = microbicidal We can further divide these chemicals: bactericidal or bacteristatic, fungicidal or fungistatic, and virucidal or virustatic.

3. Some mechanisms of microbial control

4. the elimination of all forms of the life cycles of microbes (e.g., vegetative cells, spores). Toxins and prions however, are not necessarily removed. Sterilization

5. -the reduction of the vegetative forms of most potentially hazardous and pathogenic microbes from inanimate objects. Disinfection

6. a supplemental disinfection by cleaning that is used for food preparation equipment. Sanitization

7. the inhibition or destruction of microbes on the surfaces of living organisms. Antisepsis

8. -the inactivation or removal of both toxins and microbes. Decontamination

9. – the process that delays spoilage (food and other perishables). Preservation

10. -decreasing the number of microbes in an area. Degerming

11. The ideal disinfectant: Would be fast acting Would be broadspectrum w/o causing damage to the person Would easily penetrate material to be disinfected without damaging it. Would be easy to prepare, and would be stable despite exposure to light, heat, and other environmental factors Would be cost efficient and easy to obtain and use Would not have an unpleasant odor

12. Factors that affect the activity of antimicrobial agents includes types of microbes number of microbes concentration of the antimicrobial time of exposure risk of infection environmental conditions

13. PHYSICAL WAYS TO CONTROL MICROBES

14. HEAT

15. - the use of mild heat for relatively long periods of time or the use of high heat for very short periods of time. Pasteurization

16. for 10 minutes at 100 C eliminates most vegetative cells. Boiling

17. is a common method of sterilization. It is the use of steam under pressure. The pressure increases the boiling point of water and thus increases the temperature to which water can be heated. Autoclaving

18. Dry heat involves three methods: flaming, incinerating, or baking. Dry Heat: Incinerator

19. RADIATION

20. Ionizing radiation (e.g., gamma rays, X-rays) involves rays that have such high energy that they cause biologically active molecules to lose electrons. High doses kill every organism they strike. It can be used for sterilization

21. causes the formation of pyrimidine dimers. UV radiation

22. OTHER METHODS

23. Filtration For example, filtration is used as one of the methods for water treatment

24. The Surgical Scrub This type of handwashing is used to prevent contamination of patients. It takes longer and has more steps than normal handwashing

25. Cold temperatures slow microbial growth Cold temperatures

26. (drying out) is effective against many vegetative cells Dessication

27. is a relatively new way of pasteurizing foods High Pressure processing

28. CHEMICAL METHODS OF CONTROLLING MICROBES

29. Chemicals that sterilize Very few chemicals are recommended for sterilization. These include: ethylene oxide, hydrogen peroxide, formaldehyde, and gluteraldehyde Disinfectants and Antiseptics Chemical preservatives

30. ANTIBIOTICS

31. Considerations for choosing an antibiotic 1. The antibiotic must be soluble in body fluids to be transported 2. Selective toxicity is a critically important property of abs. The therapeutic index is the dose per kg of body wt./the minimum dose per kg of body wt. that will cure the disease (the higher the TI, the better). The Therapeutic index is the highest dose a patient can tolerate without toxic effects, divided by the dose required to control a microbial infection. 3. Interactions with other substances 4. Allergic reactions 5. Stability 6. There should be minimal resistance to the drug 7. Long shelf life 8. Affordable.

32. Drugs for other infections • Antivirals • Antifungals • Antiparasitic • etc

33. INFECTIONS OF THE SKIN

34. SKIN The intact skin is part of the First Line of Defense. It functions as a physical or mechanical barrier to disease causing organisms. In addition, it secretes chemicals that destroy disease causing organisms.

35. NORMAL FLORA The normal “flora” of the skin also help prevent infection by outcompeting disease causing organisms. Examples include: • Staphylococci • Diptheroids • Fungi

36. Folliculitis (infections of hair follicles; pimples) furuncles (AKA boils, infection of has spread to adjacent tissue), and Carbuncles (a group of boils). Causative organism(s) - Staphylococcus aureus Not always limited to the cutaneous and subcutaneous tissues and can lead to very serious conditions such as septicemia (blood poisoning). DX - the presence of the infected tissues TX - drainage of the pus and antibiotics (topical or systemic) prevention - difficult because of the ubiquitous nature of S. aureus

37. Staphylococcal Scalded Skin Syndrome Part I Causative organism- S. aureus (5% of strains) A painful red flush over the body (covering 20-100%) which blisters and then sloughs. Also malaise, irritability, and fever. Very serious and mortality may be 40%. Newborns, the elderly, and the immunocompromised are more susceptible and secondary infections are possible.

38. Staphylococcal Scalded Skin Syndrome Part II DX - Gram stain and culture from the primary site of infection or from blood, skin, or nose (but not the blister fluid) TX - antibiotics, and removal of dead tissue. prevention – no prevention except` isolation of patient

39. Streptococcal impetigo Part I Causative organisms -Streptococcus pyogenes ( but also can be caused by S. aureus) Pyodermas are characterized by pus production; the most common type is impetigo. Impetigo can result from infection of an insect bite, burn, scrape or other wound. It is characterized by the formation of blisters which open and weep causing a buildup of yellow crusts. Generally not too serious, but are very contagious person to person or by fomites, however, a rare but very serious sequel can occur: Acute Glomerulonephritis

40. Streptococcal impetigo Part II DX- culture of fluid from lesions or lesions TX - oral or topical antibiotic, anti-itch creams prevention- good hygiene, prompt cleaning of wounds and avoiding people with pyodermas.

41. Rheumatic Fever can damage the heart Acute Glomerulonephritis can cause kidney failure Scarlet Fever the rash is caused by a toxin produced by S. pyogenes Sequelae of Strep Infections

42. Rocky Mountain Spotted Tick Fever Part I Causative organism - Rickettsia rickettsia (Gram negative coccobacillus), vector: ticks of the genus Dermacentor. Note the tick is note to scale- it can be very small.

43. Rocky Mountain Spotted Tick Fever Part II This disease is actually systemic but the rash is distinctive. It is a zoonosis characterized by a serious headache, muscle and joint pain, and fever, then a spotted rash develops starting on the wrists and ankles & moving to the arms & legs & eventually covering the entire body. In severe untreated cases, gangrene may develop, as well as cardiovascular disruption, delirium, convulsions, deafness, DIC, and coma. This disease can be rapidly fatal. Mortality without treatment is @ 20% but with early treatment it is reduced to less than 5%.

44. Rocky Mountain Spotted Tick Fever Part III DX - fluorescent antibody staining, serological methods, DNA probe, or sometime early biopsies. It is hard to grow and moreover it is dangerous to culture. TX – early antibiotics (even without confirmation) Prevention - avoidance of ticks, using repellents, wearing protective clothing, carefully inspecting the body for ticks and carefully removing any that are found (without crushing them). No vaccination is available but one is under development

45. Lyme disease Part I Causative organism - Borrelia burgdorferi, vector- tick (genus Ixodes) Not normally fatal but can be disabling. Zoonosis The first phase - a rash at the site of the bite erythema chronicum migrans that looks like a bull’s eye (present in 2/3s of the cases), and flu-like symtoms: fever, enlarged lymph nodes, headache, joint and muscle pains, and stiff neck.

46. Lyme disease Part II The second phase - neurological and cardiovascular involvement (due to impairment of the conduction system and thus sometimes requiring a pace maker temporarily) and may be characterized by dizziness and fainting and one or more of the following: paralysis of the face, severe headache, pain on moving the eye, emotional instability, concentration problems, fatigue, and impairment of nerves of the arms and legs.

47. Lyme disease Part III The third phase, if it develops involves joint pain, arthritis, swelling and tenderness about 6 months after the ECM. In 60% of cases, chronic nervous system impairments occur (localized pain, paralysis, and depression)

48. Lyme disease Part IV DX - Serological testing, also erythema chronicummigrans is diagnostic when present TX - early treatment with antibiotics Prevention – prevention of tick bites. One way is to shove your pants into your socks so that ticks can not get to your skin.

49. Hunter with Lyme Disease

50. Chicken pox or varicella Part I Causative organism - Varicella-zoster virus Chicken pox is usually mild but more serious in adults and characterized by the presence of a rash [beginning as small, red macules (spots), papules (bumps), and vesicles (blisters)] that itch. In adults the symptoms are more severe and pneumonia may develop (in about 20% of cases). In addition, if a pregnant woman gets chicken pox five prior to and up to two days after birth, the newborn may have serious complications (congenital varicella syndrome). The incidence of chicken pox was previously as high as 3.7 million cases/year, but has decreased since the vaccine became available. Humans are the only reservoirs.