Basic Science - Microbiology

  1. Autoclave 2073/7

    Define Sterilization .Describe the importance of MRSA and its prevention in the hospiatal 2070/5

    Define Sterilization . Describe the method of sterilization of operation time 2072
  2. Define sterilization and disinfection.
    • Sterilization - It is a process by which  the surface, medium or articles are completely freed of all the vegetative or spore state by denaturation of the protoplasmic proteins. 
    • Spores of Bacilus thermophilus are used to assess the completeness of steriliation. 

    Disinfection - It is the process of removing or destroying all pathogenic organisms or all those organisms which are capable enough to give rise to infection.
  3. Methods of sterilization?
    • A. Physical methods
    • 1. Sunlight 
    • 2. Drying 
    • 3. Heat 
    • - Dry heat - Flaming, incineration, hot air oven (1600C for 2 hours)
    • - Moist heat - Pasteruriation (720C for 15-20 min, 630C for 36 minutes), Boiling, Autoclave
    • 4. Filtration 
    • - Cellulose membrane filters 
    • - Seitz filters 
    • 5. Radiation - mercury vapour lamps, cathode rays
    • 6. Ultrasonic and sonic vibrators. 

    • B. Chemical methods
    • - Alcohol - ethyl and isopropyl alcohol
    • - Aldehyde - Formaldehyde, 2% gluteraldehyde (cidex)
    • - Dyes - Aniline dyes, Malachite green, acridine dyes 
    • - Halogens - Iodine, Hypochlorite
    • - Phenol 
    • - Gases - Ethylene oxide, Formaldehyde gas
  4. Use of cidex?
    • 2% glutaraldehyde is also called as Cidex 
    • For steriliation, immersion for 4  hours 
    • For disinfection, immersion for 15-20 minutes 

    It is used for disinfection of cystoscope, laparoscope
  5. Autoclave
    • 1210C at 15 lb/inch2
    • 15 minutes for rubber goods 
    • 30 minutes for metalic
  6. Gas oxide?
    • Ethylene oxide gas for 12 hours 
    • Formaldehyde gas for 1 hour
  7. MOA of betadine?
    Release iodine slowly and provide longer duration of antiseptic effect.
  8. Choice of steriliation?
    • Metalic and rubber objects - autoclave 
    • Glasses - hot air oven
    • Sharp and plastic instruments cannot be sterilied by autoclave and boiling. Sharp objects sterilied by gluteraldehyde.
  9. Opportunistic Infection. [TU 2073/7] 

    Role of infection control committee to control hospital associated infection. [TU 2073/7] 

    Short note on Nosocomial infections. [TU 2056]

    Define nosocomial infection.Name the organisms commonly associated with hospital acquired infections. Describe the control measures of this infection. 2054

    What are the sources of infections in the hospital and how it can be controlled ? 2072
    A hospital-acquired infection (HAI), also known as a nosocomial infection, is an infection that is acquired in a hospital or other health care facility, and not present or at incubation period at the time of admission. To emphasize both hospital and nonhospital settings, it is sometimes instead called a health care–associated infection (HAI or HCAI). 

    Infection is spread to the susceptible patient in the clinical setting by various means. Health care staff can spread infection, in addition to contaminated equipment, bed linens, or air droplets. The infection can originate from the outside environment, another infected patient, staff that may be infected, or in some cases, the source of the infection cannot be determined.

    • Types
    • Hospital-acquired pneumonia
    • - Ventilator-associated pneumonia
    • Urinary tract infection
    • Gastroenteritis
    • Puerperal fever

    • Organisms
    • Staphylococcus aureus
    • Methicillin resistant Staphylococcus aureus
    • Candida albicans
    • Pseudomonas aeruginosa

    • Main routes of transmission
    • Contact transmission - The most important and frequent mode of transmission
    • Droplet transmission - by coughing, sneezing, and talking, and during the performance of certain procedures, such as bronchoscopy
    • Airborne transmission - Legionella, Mycobacterium tuberculosis and the rubeola and varicella viruses
    • Common vehicle transmission - contaminated items, such as food, water, medications, devices, and equipment
    • Vector borne transmission - vectors such as mosquitoes, flies, rats, and other vermin transmit microorganisms

    • Prevention -
    • Sterilization
    • Isolation
    • Handwashing
    • Gloves
    • Surface sanitation
    • Antimicrobial surfaces
  10. What is MRSA. Write in short its importance in nosocomial infection. [TU 2066,68,73/2]
    • Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for several difficult-to-treat infections in humans.
    • MRSA is any strain of Staphylococcus aureus that has developed, through horizontal gene transfer and natural selection, multi- resistance to beta-lactam antibiotics, which include the penicillins (methicillin, dicloxacillin, nafcillin, oxacillin, etc.) and the cephalosporins.

    • Signs and symptoms -
    • S. aureus most commonly colonizes under the anterior nares (the nostrils). The rest of the respiratory tract, open wounds, intravenous catheters, and the urinary tract are also potential sites for infection.
    • Healthy individuals may carry MRSA asymptomatically for periods ranging from a few weeks to many years.
    • The initial presentation of MRSA is small red bumps that resemble pimples, spider bites, or boils; they may be accompanied by fever and, occasionally, rashes. Within a few days, the bumps become larger and more painful; they eventually open into deep, pus-filled boils.
    • About 75 percent of community-associated (CA-) MRSA infections are localized to skin and soft tissue and usually can be treated effectively. They can affect vital organs and lead to widespread infection (sepsis), toxic shock syndrome, and necrotizing pneumonia.
    • The most common manifestations of CA-MRSA are simple skin infections, such as impetigo, boils, abscesses, folliculitis, and cellulitis. Rarer, but more serious, manifestations can occur, such as necrotizing fasciitis and pyomyositis (most commonly found in the tropics), necrotizing pneumonia, and infective endocarditis (which affects the valves of the heart), and bone (osteomyelitis) and joint infections.

    • Risk Factors -
    • • People who are frequently in crowded places, especially with shared equipment and skin-to-skin contact
    • • People with weak immune systems (HIV/AIDS, lupus, or cancer sufferers; transplant recipients, severe asthmatics, etc.)
    • • Diabetics
    • • Intravenous drug users
    • • Users of quinolone antibiotics
    • • The elderly
    • • School children sharing sports and other equipment

    • Prevention -
    • Screening programs
    • Surface sanitizing
    • Hand Wahsing
    • Proper disposal of hospital gowns
    • Isolation
    • Restricting antibiotics use - Glycopeptides, cephalosporins, and, in particular, quinolones are associated with an increased risk of colonisation of MRSA.

    • Treatment -
    • Drug of choice for treating CA-MRSA - Vancomycin
    • Newer drugs, such as linezolid (belonging to the newer oxazolidinones class) and daptomycin, are effective against both CA-MRSA and HA-MRSA.
  11. Plasma sterilization?
    • Ionized H2O2 
    • <60 C - low temperature sterilization 

    OPA - Orthopaldehyde
  12. Oncogenic viruses
    • Papovavirus - Papilloma
    • Herpes 
    • - HSV 16,18 - Ca Cervix 
    • - Cytomegalovirus - salivary gland tumor 
    • - EBV
    • Hepatitis virus - HBV, HCV
    • RNA virus - HTLV
  13. Diseases caused by EBV?
    • Oral hairy leukoplakia
    • Burkitt lymphoma 
    • Infectious mononucleosis 
    • Nasopharyngeal carcinoma 
    • Lymphoma (Hodgkins and B-cell) [@ Osama BIN Laden]
  14. Describe the methods of transport of specimen for anaerobic bacterial culture. [TU 2064,70/5]

    Methods of collection, transportation and cultivation of anaerobic bacteria 2067/2

    Laboratory diagnosis of deep seated wound infection 2064/12
    • A. Sampling for anaerobic culture 
    • - Aspirate using needle and syringe
    • - If no pus or fluid comes on aspiration, inject sterile saline subcutaneously and resample 
    • - The last and least way  is to use deep swab and rapidly transfer to anaerobic transport media. 
    • - Rapidly transfer to anaerobic transport media 
    • - Do not refrigerate 
    • - Should reach the lab in less than 2 hours
    • - If delay id expected, use transport kit 

    • B. Culture methods 
    • 1. Use of media containing reducing substances (Robertson Cooked Meat broth or Thioglycolate broth).
    • 2. Culture away from O2 (Deep agar tubes).
    • 3. Chemical exclusion of O2 (anaerobic Gas Pak system).
    • 4. Mechanical exclusion of O2 (anaerobic incubator).
    • Image Upload 1

    Avoid exposure to cold - anaerobes are sensitive to cold. Avoid drying of sample.
  15. What is anaerobiosis?
    • It refers to life in oxygen free atmosphere. Anaerobiosis can be established by 
    • - Displacement of oxygen - culture in vacuum in a vacuum dissicator, displacement of oxygen by inert gas. 
    • - Absorption of oxygen by chemicals - Gas-pak, mixture of powdered chromium and sulfuric acid, pyrogallic acid
    • - By displacement and combustion of oxygen
    • - By biological methods 
    • - By incorporating reducing agents in culture media
  16. Explain the significance of thyroid function test in a chronically ill patient . 2070/12
    • Write difference between cellular and humoral immunity. 2068/5
    • Describe the principle of antimicrobial therapy 2070/5
    • Discuss how would you reduce surgical wound infection 2070/5
    • Describe principles of antibiotic therapy 2067/2
    • How does cellular immunity differ from humeral immunity. 2066/6
    • Enumerate the types of immunoglobulin. 2056/2
    • Sketch a diagram of IgG and label its different parts clearly. 2056
    • Compare and contrast between IgG and IgM. 2056
    • Write short notes on any three:
    • Value of western Blot to diagnose HIV infections 2056
    • Pathogenic and nonpathogenic micro-organisms 2056
    • Widal test 2056
    • Describe the etiopathogenesis of AIDS. 2054
    • Short notes in Hep C infection 2068/2
Card Set
Basic Science - Microbiology