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Microbial Ecology – study of numerous Parasitism – a symbiotic relationship that is of interrelationships between microorganisms and benefit to one party (the parasite) at the expense the world around them. of the other party (the host). m...

Microbial Ecology – study of numerous Parasitism – a symbiotic relationship that is of interrelationships between microorganisms and benefit to one party (the parasite) at the expense the world around them. of the other party (the host). microbes – microbes Parasites – organisms that live on or in other microbes – organisms organisms (host) at whose expense they gain some microbes – nonliving world around them advantage. Host – living organism that harbors another living ❑ Ectoparasites – parasites that live on the organism. exterior of its host. Symbiosis – living together or close association of ❑ Endoparasites – parasites that live in the two dissimilar organisms. internal organs or tissues of its host. Neutralism – neither symbiont is affected by the 2 Types of Parasites: relationship. 1. Facultative Parasite – organisms that can Commensalism – beneficial to one symbiont and be parasitic but do not have to live as a of no consequence to the other. parasite. In other words, it can live an Parasitism – beneficial to one symbiont and independent life, apart from a host. detrimental to the other symbiont. Ex. Free-living amebae (Naegleriasis) – can cause Mutualism – beneficial to both symbionts. keratoconjunctivitis and Primary Amebic Meningoencephalitis. Indigenous Microbiota “normal flora” - includes 2. Obligate Parasite – has no choice; to all the microbes that reside on and within that survive, it must be a parasite. person. - Most parasites that infect humans are Bacteria, Fungi, Protozoa, Viruses obligate parasites. Key Notes: Parasitic Protozoa is classified taxonomically by ▫ The body is constantly exposed to their mode of locomotion: microorganisms. o Pseudopodia – move by “false feet” ▫ A fetus has no indigenous microflora. o Flagellates – move by whiplike flagella ▫ Destruction of the resident microflora o Ciliates – move by hairlike cilia disturbs the delicate balance established  Sporozoa (sporozoans) – have no between the host and its microorganisms. pseudopodia, flagella, or cilia, and therefore ▫ When the number of usual resident exhibit no motility. microbes is greatly reduced, opportunistic invaders can more easily establish Common Protozoal Infections of Humans themselves within those areas. Gastrointestinal Tract ▫ Such an overgrowth or population Amebiasis – may be asymptomatic, mild, or severe explosion of an organism usually present in and is often accompanied by dysentery, fever, low numbers is called superinfection. chills, bloody or mucoid diarrhea, and colitis. Parasite: Entamoeba Hystolytica Microflora of the SKIN M.O.T: - The resident microflora of the skin consists ▪ Ingestion of fecally contaminated food or primarily of bacteria and fungi – as many as water 300 different species, depending on the ▪ Flies transporting cysts to food anatomical location. The number of diff. ▪ Via fecally soiled hands of infected food types of microbes varies greatly from body handlers part – body part and from person – person. ▪ Oral–anal sexual contact Most common bacteria: (anaerobes) ▪ Anal intercourse involving multiple sex + Staphylococcus partners + Corynebacterium Patient Care: use standard precaution + Propionibacterium Factors: Genitourinary Tract  Anatomical location Trichomoniasis – sexually transmitted which can  Amount of moisture present cause vaginitis in women with a profuse, thin,  PH foamy, malodorous, greenish–yellowish discharge  Temperature Parasite: Trichomonas vaginalis  Salinity M.O.T:  Presence of Chemical Wastes (urea & fatty ▪ Direct contact with vaginal and urethral acids) discharge during sexual intercourse  Presence of other Microbes, which may be Patient Care: use standard precaution producing toxic substances Key Points: Circulatory System Moist, warm conditions where there are Malaria – systemic sporozoan infection with many sweat and oil glands; stimulate the malaise, fever, chills, sweating, headache, and growth of many different microorganisms. nausea. The surface of the skin near mucosal - It may be accompanied by cough, diarrhea, openings of the body is inhabited by respiratory distress, shock, renal and liver  bacteria present in various excretions and failure, pulmonary and cerebral edema, secretions. coma, and death. Frequent washing with soap and water Parasite: Plasmodium vivax; Plasmodium removes most of the potentially harmful falciparum (most deadly); Plasmodium malariae; transient microorganisms. Plasmodium ovale M.O.T: Microflora of the EARS ▪ Injection of sporozoites into the Middle and inner ear are sterile bloodstream by an infected female The outer ear and auditory canal have Anopheles mosquito while taking a blood normal flora meal. Microorganism presents are same we see ▪ Blood transfusion; blood–contaminated on skin needles/syringes Patient Care: use standard precaution Microflora of the EYES The external surface of the eye is lubricated, Helminths Infections of Human cleansed, and protected by tears, mucus, Helminths – “parasitic worm”; multicellular, and sebum. eucaryotic microorganism. Tears and the presence of the enzyme 2 Major Divisions: lysozyme and other antimicrobial 1. Nematodes – round worms; cylindrical, substances found in tears greatly reduce elongated bodies that taper at both ends. the numbers of indigenous microflora 2. Flat Worms – flattened ribbon-like. organisms found on the eye surfaces. ❖ Cestodes (tapeworms) – segmented body with a head (scolex) that attaches Microflora of the RESPIRATORY TRACT to host’s intestines. It is divided into two parts: upper and ❖ Trematodes (flukes) – leaf-shaped lower respiratory tract. body, can be found in liver, lungs, or Many microorganisms found in the healthy blood of their host. nose and throat are harmless but are Anatomical Location: opportunistic microorganisms. Skin Healthy carriers – harbor virulent (disease- Disease: Onchocerciasis “river blindness” causing) pathogens in their nasal passages Helminth: Onchocerca volvulus – microfilariae or throats, but do not have the diseases (tiny pre-larval stages of these helminths are found associated with them. in the skin. The lower respiratory tract is usually sterile Muscle because the mucous membranes and lungs Disease: Trichinosis Helminth: Trichinella spiralis have defense mechanisms. Subcutaneous Tissues Disease: Dracunculiasis Microflora of the ORAL CAVITY Helminth: Dracunculus medinensis; also known as Anaerobic microorganisms flourish in gum the guinea worm. margins, crevices between the teeth, and Eyes deep folds (crypts) on the surface of the Disease: Onchocerciasis tonsils. Loiasis Neglect in dental hygiene allows growth of Helminths: Onchocerca volvulus – microfilariae bacteria, with development of dental enter the eyes, causing an intense inflammatory carries (tooth decay), gingivitis (gum reaction. disease), and more severe periodontal Loa loa – also known as “African diseases. eyeworm”. The most common organisms in the Respiratory System indigenous microflora of the mouth are Disease: Paragonimiasis various species of alpha-hemolytic Helminth: Paragonimus westermani – the lung streptococci. fluke. Common bacteria are gram (-) and (+) Microflora of the GASTROINTESTINAL TRACT Gastric enzymes and acidic pH of the stomach usually prevent growth of indigenous microflora, and most transient microbes. Few microflora usually exist in the duodenum, because bile inhibits their growth, but many are found in the lower parts of jejunum and ileum. Many of the microflora of the colon are opportunists, causing disease only when  they gain access to other areas of the body – like Escherichia coli. Microflora of the URINARY TRACT The healthy kidney, ureters, and urinary bladder are sterile. Distal urethra and external urethra harbor many microorganisms. Recurring UTIs often develop when there is an obstruction/narrowing of the urethra and allows invasive organisms to multiply. Microflora of the REPRODUCTIVE SYSTEM The reproductive systems of both men and women are usually sterile, except for the vagina. Women vagina during pubescent and menopausal period become alkaline – supporting the growth of microorganism. During childbearing age – the vagina is acidic. Acidic vagina supports the growth of lactobacilli. Lactobacilli byproduct is lactic acid that inhibits the production of opportunistic microorganisms that may result in bacterial vaginosis and yeast infection. NOSE AND G.I G.U SKIN MOUTH OROPHARYNX NASOPHRAYNX TRACT TRACT Anaerobic Gram-negative cocci - + - - - - Anaerobic Gram-positive cocci - + - + + + Bacteroides spp. ± + - + + + Candida spp. + ± - - - + Clostridium spp. + - - - + + Diphtheroids + - + + - + Enterobacteriaceae - - - - + ± Enterococcus spp. - ± ± - + + Fusobacterium spp. - ± ± + + - Haemophilus spp. - - + + - - Lactobacillus spp. + + - - - + Micrococcus spp. + - - - - - Neisseria meningitidis - - ± ± - - Prevotella/Porphyromonas spp. - + - + - - Staphylococcus spp. + + + + + + Streptococcus spp. ± + + + - - (+) commonly present; (±) less commonly present; (-) absent Sometimes referred to as enteric bacilli (includes Escherichia, Klebsiella, Proteus spp.)