MICROPARA

• Ecology


  The systematic study of the interrelationships that exist between organisms and their environment
• Microbial Ecology


  The study of the numerous interrelationships between microbes with other microbes, with non-microbial organisms, and with the non-living world around them
• Symbiosis


  The living together or close association of two dissimilar organisms
• Symbionts


  The organisms in a symbiotic relationship
• Normal Flora


  Also referred to as indigenous microbiota, includes all the microbes (bacteria, fungi, protozoa, and viruses) that reside on and within a person, sometimes referred to as the human microbiome
• Resident Flora


  Microbes that permanently reside in specific anatomical sites of the human body
• Transient Flora


  Microbes that are temporarily harbored on the superficial surface of the body
• Areas of the body where most of the indigenous microbiota reside

  • Ears and eyes
  • Mouth and upper respiratory tract
  • Skin
  • GIT
  • GUT
• Acquisition of normal microbiota

  1. Fetus is devoid of microbiota

  2. Microbiome begins to develop when amniotic membrane ruptures and microorganisms come in contact with newborn during birth

  3. Microbes enter mouth and nose during passage through birth canal

  4. First breath is loaded with microorganisms

  5. First meals provide progenitors of resident microbiota for the colon

  6. Staphylococcus and other microbes are transferred from skin of medical staff and other people
• Skin


  • It is the most exposed to microorganisms
  • Factors that eliminate non-resident flora from the skin include lysozyme, acidic pH, free fatty acids, and constant sloughing
• Resident microbiota of the skin

  • Bacteria
  • Fungi
• Skin regions and their microbiota

  • Axilla, perineum, and toe webs - higher moisture, temperature and surface levels, inhabited by more microbes, predominantly Gram-negative bacteria
  • Face and trunk - high density of sebaceous glands, encourage growth of lipophilic organisms like Propionibacterium spp. and Malassezia spp.
  • Upper arms and legs - relatively drier and exposed to variable surface temperature, harbor fewer and more diverse microbes than other areas
• The middle ear and the inner ear are usually free of microbes
• The outer ear and the auditory canal contain the same microbes as on the skin
• The eyes are lubricated and cleansed by tears, mucus, and sebum, so few microbes are present
• The nose is cooler than the rest of the respiratory system and has some unique microbiota
• The microbiota of the trachea and bronchi are sparse compared to those of the nose and mouth
• The alveoli of the lungs have no natural microbiota
• Carriers harbor virulent pathogens in their nasal passages or throats, but do not have the diseases usually caused by these pathogens, e.g. diphtheria, pneumonia, meningitis, and whooping cough
• The lower respiratory tract is usually free of microbes
• The oral cavity affords a shelter for numerous anaerobic and aerobic bacteria
• Careless dental hygiene may cause dental caries, gingivitis, and periodontitis
• Oral bacteria


  • Streptococci
  • Lactobacilli
  • Staphylococci
  • Corynebacterial, with a great number of anaerobes, especially bacteroides
• There are minimal microbes in the stomach because of its acidic content
• Helicobacter pylori


  Produces urease, which increases gastric pH, and enables it to colonize the stomach
• The colon (large intestine) contains the largest number and variety of microbes of any colonized area of the body: an estimated 500 to 600 different species—primarily bacteria
• The colon is anaerobic; bacteria in colon are mostly obligate (95-99%), aerotolerant, and facultative anaerobes
• Many members of the colon microbiota are opportunists
• Common microbes in the colon

  • Bacteroides fragilis (most common)
  • Bifidobacterium bifidum (Lactobacillus bifidus) (predominant in breast-fed infants)
  • Lactobacillus acidophilus (predominant in bottle-fed infants)
  • E.coli and other Enterobacteriaceae (predominant facultative anaerobe)
• Kidney, ureters, and urinary bladder are usually sterile
• The distal urethra and its external opening harbor many microbes, including bacteria, yeasts, and viruses
• The most frequent causes of urethral infections include Chlamydia trachomatis, Neisseria gonorrhoeae, and mycoplasmas
• The male and female reproductive systems are usually sterile, except for the vagina
• Beneficial roles of normal flora

  • Synthesis of vitamins K and B12
  • Microbial antagonism
• Microbial antagonism


  Microbes versus microbes, they prevent other microbes from becoming established
• Opportunistic pathogens


  Microbes that "hang around", waiting for the opportunity to cause infection
• The delicate balance of the indigenous microbiota can be upset by antibiotics, other types of chemotherapy, and changes in pH
• Biofilms


  Complex communities of assorted organisms, consisting of a variety of different species of bacteria plus a sticky polysaccharide that the bacteria secrete, very resistant to antibiotics and disinfectants

  
• Biofilms are medically significant because they form on urinary catheters and medical equipment and can cause diseases like endocarditis
• Blood agar


  Contains general nutrients with blood added to the agar, certain Gram-positive bacteria produce exotoxins that hemolyze (rupture) the RBC in the agar