PMLS#20-21

• Pathogen is a microorganism that is capable of causing disease in the body
• Normal flora (resident bacteria present in certain areas of the body)
• Specimen collection

  • collect the sample from the area of infection
  • bacterial culture specimens should be collected before antibiotics are introduced
  • use the correct collection and transportation methods
  • always collect a sufficient quantity of sample for testing
  • appropriately labeled
  • use sterile supplies
• Personnel

  • all personnel participating in the collection, processing, or testing of microbiological specimens must be appropriately trained in all procedures
  • should participate regularly in competency testing
  • wear appropriate personal protective equipment(PPE)
• Media

  • provides nutrition for microorganisms when grown in the laboratory environment
  • cannot be allowed to dry out or become contaminated
  • verify that the correct medium is used for each type of specimen collection
  • medium performance should be verified on a regular basis
• Stains

  • All products used for staining microorganisms have expiration dates provided by the manufacturer, after which the stains must be discarded. Stain performance should be verified on a regular basis by staining microorganisms with predictable staining characteristics to observe staining patterns.
• Type of Media

  Culture media is classified into categories based on whether the medium enriches the growth of all bacteria or selective inhibits growth of certain bacteria.
• Type of Media

  Selective media have additives that prevent the growth of certain types of bacteria while promoting the growth of other select species.
• Type of Media

  Differential media allow for different types of bacteria to be identified based on an indicator.
• Type of Media

  Enriched media include nutrients that allow for a wide variety of organisms to grow.
• Solid gel is provided in a tube (called a slant) or in a Petri dish. Liquid medium ( usually called nutrient broth) comes in a tightly sealed tube.
• Sequela is a serious secondary complication or infection that follows as a result of the primary bacterial infection.
• Throat samples are used most commonly to test for streptococcal infections with a group A strep screen rapid test completed in the physician office.
• The most common cause of streptococcal throat infection

  Group A streptococcus
• Sputum is the substance produced from a deep cough or from aspiration caused by inserting a tube down the patient's throat.
• Urine samples for culture must be collected in a manner that reduces potential contamination by non-pathogenic microorganisms.
• Mycobacterium tuberculosis, the causative agent of tuberculosis infection
• Blood Culture Collection

  • Health-care providers order blood culture collections when they suspect that the patient may have pathogenic bacteria in the bloodstream, a condition known as septicema.
• Cerebrospinal fluid (CSF) samples are used to help diagnose various diseases of the central nervous system.
• Genital Samples

  • Another common infection of the genitals is trichomoniasis, which is a sexually transmitted disease caused by the parasite Trichomonas vaginalis.
• Wound cultures may be ordered when a patient has redness, swelling, drainage, or heat in or around a wound.
• Wound Cultures

  • If exudate (fluid from the blood vessels in the area of the infection) or pus is present, the health-care provider may culture this drainage.
• Wound Cultures

  • A Gram stain is often performed from the original collection swab at the same time the culture is set up.
• Stool Specimens

  • Sometimes the physician may also ask for a specimen to be collected to check for the presence of parasites in the gastrointestinal (GI) tract. This is known as an ova and parasite examination (O&P). Stool specimens for bacterial cultures are collected in a sterile cup.
• Nasopharyngeal specimen are usually collected by entering the pharynx through the nose, but they may also be collected by going through the mouth and "sweeping" the area of the pharynx that is above the uvula.
• Eye Cultures

  • Samples from the eye may be taken from the conjunctiva
  • less commonly are obtained as corneal scrapings or an aspirate from the eyeball
• Ear Cultures

  • Otitis media is the common type of ear infection, and usually develops as a result as a result of blockage of the eustachian tube.
• Ear Cultures

  • A procedure called tympanocentesis may be formed, in which the health-care provider inserts a needle through the tympanic membrane and aspirates a sample of the fluid that is built up in the middle ear.
  • Another procedure that may allow access to the fluid is a myringotomy, in which a tiny incision is made into the eardrum to allow for drainage of the infected fluid.
• Ear Cultures

  • Otitis externa is condition that is often known as a swimmer's ear.