Bacteria Important in Human Health PDF

BACTERIA IMPORTANT IN HUMAN HEALTH Prof. Dr. Emrah Ruh NEU Faculty of Medicine Department of Medical Microbiology and Clinical Microbiology Role of bacteria in human health ◻ Protective Microbiota (normal flora of human body) ◻ Disease causing Pathogenic bacteria Opportunistic...

BACTERIA IMPORTANT IN HUMAN HEALTH Prof. Dr. Emrah Ruh NEU Faculty of Medicine Department of Medical Microbiology and Clinical Microbiology Role of bacteria in human health ◻ Protective Microbiota (normal flora of human body) ◻ Disease causing Pathogenic bacteria Opportunistic bacteria Microbiota (Normal flora of human body) ◻ Microorganisms begin colonization in and on the surface of the body soon after birth ◻ Microorganisms that establish permanent colonies inside or on the body and do not generally produce disease make up the normal microbiota ◻ Transient microbiota are microbes that are present for various periods and then disappear Microbiota (Normal flora of human body) ◻ Relationship between normal microbiata and the host: Symbiosis (mutualism) ◻ From the host; normal flora members derive nutrients, environment and protection ◻ From the normal flora members; the host gains protection against the pathogenic microorganisms and obtain digestive benefits Microbiota (Normal flora of human body) ◻ Parts of the human body that contains normal flora: Skin Eyes (conjunctiva) Nose and throat (upper respiratory system) Mouth Gastrointestinal tract Genitourinary tract Microbiota (Normal flora of human body) Microbiota (Normal flora of human body) ◻ Normal flora contains many microorganisms ◻ The most important members are summarized in the next slides...  Microbiota (Normal flora of human body) ◻ Skin: Staphylococcus epidermidis Gram-positive cocci Facultative anaerobic  Microbiota (Normal flora of human body) ◻ Mouth: Streptococcus mutans Gram-positive cocci Facultative anaerobic Cause tooth decays  Microbiota (Normal flora of human body) ◻ Gastrointestinal tract: Enterobacteriaceae (enteric bacteria such as Escherichia coli) Gram-negative bacilli Facultative anaerobic  Microbiota (Normal flora of human body) ◻ Genitourinary tract: Vagina: Lactobacillus Gram-positive bacilli Facultative anaerobic or strictly anaerobic Low pH of the vagina Role of bacteria in human health ◻ Protective Microbiota (normal flora of human body) ◻ Disease causing Pathogenic bacteria Opportunistic bacteria Disease causing bacteria ◻ Pathogenic bacteria Capable of causing disease ◻ Opportunistic bacteria Capable of causing disease only when the host’s immune system is impaired May include some of the normal flora members (catheters, surgical operations,...) Disease causing bacteria ◻ Infection Multiplication of an infectious agent within the body ◻ Infectious disease Clinically evident illness (characteristic medical signs and/or symptoms of disease) resulting from infection Transmission: Portals of entry of pathogenic bacteria into the body ◻ Respiratory tract (upper and lower airways) ◻ Gastrointestinal tract (primarily mouth) ◻ Genital and urinary tracts ◻ Capillary ◻ Skin ◻ Eyes ◻ Ears Transmission: Routes of entry of pathogenic bacteria into the body ◻ Ingestion ◻ Inhalation ◻ Trauma ◻ Needlestick ◻ Arthropod bite ◻ Sexual transmission Transmission – Ingestion Transmission – Inhalation Transmission – Trauma Transmission – Needlestick Transmission – Arthropod bite Transmission – Sexual Disease causing bacteria ◻ A detailed information will be given during the “Infectious Diseases Committee” in the third year ◻ This lecture will summarize distinct bacteriological features and significant clinical diseases of several important bacteria only Staphylococcus aureus Important bacteriological features ◻ Gram-positive cocci ◻ Cocci form grape-like clusters ◻ Facultative anaerobic ◻ β-hemolytic ◻ Toxin production (+) ◻ MRSA (methicillin-resistant Staphylococcus aureus) Staphylococcus aureus Important clinical diseases ◻ Skin and soft tissue infections ◻ Gastroenteritis ◻ Toxic shock syndrome in tampon use Staphylococcus epidermidis Important bacteriological features ◻ Gram-positive cocci ◻ Cocci form grape-like clusters ◻ Facultative anaerobic ◻ Non-hemolytic ◻ Normal flora of the skin ◻ Wound infections, catheter and prosthetic device infections Streptococcus pyogenes Important bacteriological features ◻ Gram-positive cocci ◻ Cocci form chains ◻ Group A β-hemolytic streptococci (GABHS) ◻ Facultative anaerobic ◻ β-hemolytic ◻ Toxin production (+) Streptococcus pyogenes Important clinical diseases ◻ Skin and soft tissue infections ◻ Streptococcal sore throat (pharyngitis) (the most common infection caused by S. pyogenes) Streptococcus pyogenes Important clinical diseases ◻ Scarlet fever The toxin is introduced by a lysogenic phage Rash Strawberry tongue Streptococcus pneumoniae Important bacteriological features ◻ Gram-positive diplococci ◻ α-hemolytic ◻ Polysaccharide capsule (+) Streptococcus pneumoniae Important clinical diseases ◻ Pneumonia ◻ Sinusitis and otitis media ◻ Meningitis  Corynebacterium diphtheriae Important bacteriological features ◻ Gram-positive bacilli ◻ Metachromatic granules (+) ◻ Toxin production (+) Corynebacterium diphtheriae Clinical disease ◻ Diphtheria The toxin is introduced by a lysogenic phage  Bacillus anthracis Important bacteriological features ◻ Gram-positive bacilli ◻ Centrally located spores (+) ◻ Capsule (+) Polypeptide (poly-D-glutamic acid) ◻ Toxin production (+) Bacillus anthracis Clinical disease ◻ Anthrax Inhalation anthrax (biological weapons) Cutaneous anthrax Mycobacterium tuberculosis Important bacteriological features ◻ Gram-positive cell wall ◻ Aerobic rods ◻ Can not be stained with Gram ◻ Lipid-rich cell wall Contain mycolic acids ◻ Intracellular  Mycobacterium tuberculosis Clinical disease ◻ Tuberculosis (TB) Pulmonary TB (cavity formation in the lungs) Disseminated TB Black arrows: Cavity formation Legionella pneumophila Important bacteriological features ◻ Pleomorphic, Gram-negative, aerobic rods ◻ Intracellular ◻ Can live in lakes and streams, air conditioning systems, water systems (showers, etc.), amoeba, etc. Legionella pneumophila Clinical diseases ◻ Pontiac fever (influenza-like illness) ◻ Legionnaires’ disease (severe form of pneumonia) Clostridium tetani Important bacteriological features ◻ Gram-positive rods ◻ Anaerobic ◻ Terminal spores (+) ◻ Toxin production (+) Clostridium tetani Clinical disease ◻ Tetanus Muscle contractions Clostridium botulinum Important bacteriological features ◻ Gram-positive rods ◻ Anaerobic ◻ Subterminal spores (+) ◻ Toxin production (+) ◻ Botox…  Clostridium botulinum Clinical disease ◻ Botulism Lack of muscle contraction (decreased muscle tone) Foodborne, wound, infant botulism… Children younger than 1 year should not eat honey  Pseudomonas aeruginosa Important bacteriological features ◻ Gram-negative bacilli ◻ Aerobic ◻ Toxin production (+) ◻ Diffusible pigments (+)  Pseudomonas aeruginosa Important clinical diseases ◻ Pulmonary infections Patients with cystic fibrosis ◻ Infections of burn wounds  Bordetella pertussis Important bacteriological features ◻ Gram-negative coccobacilli ◻ Aerobic ◻ Toxin production (+) Bordetella pertussis Clinical disease ◻ Pertussis (whooping cough) Neisseria species Important bacteriological features ◻ Gram-negative diplococci ◻ Aerobic ◻ Intracellular ◻ Neisseria meningitidis: Polysaccharide capsule (+) Neisseria species Important clinical diseases ◻ Neisseria meningitidis: meningitis in infants and children ◻ Neisseria gonorrhoeae: urogenital infections (gonorrhea)  Treponema pallidum Important bacteriological features ◻ Gram-negative spiral bacilli ◻ Spirochetes ◻ Can not stained with Gram Dark-field microscopy ◻ Can not be cultured Treponema pallidum Clinical disease ◻ Syphilis Typical “chancre” formation (primary syphilis) Chlamydia trachomatis Important bacteriological features ◻ Gram-negative bacteria ◻ Lack rigid peptidoglycan ◻ Can not be stained with Gram ◻ Cultivated in cell cultures only Chlamydia trachomatis Important clinical diseases ◻ Ocular infections (trachoma, conjunctivitis) ◻ Urogenital infections Rickettsia species Important bacteriological features ◻ Gram-negative rods ◻ Aerobic ◻ Intracellular ◻ Can not be stained with Gram ◻ Cultivated in cell cultures only ◻ Transmitted by arthropod vectors Rickettsia species Important clinical diseases ◻ Spotted fever ◻ Typhus Spotted fever Enterobacteriaceae Important bacteriological features ◻ Gram-negative bacilli ◻ Facultative anaerobic Enterobacteriaceae Important bacteriological features ◻ Some bacteria (eg, Escherichia coli) are normal flora members (opportunistic infections) ◻ Some bacteria (eg, Salmonella, Shigella,…) are always associated with disease ◻ Some bacteria (eg, Escherichia coli) produce toxins (exotoxins) ◻ Endotoxin is an important virulence factor  Enterobacteriaceae Important bacteriological features ◻ Definitive identification requires special growth media and biochemical tests (eg, oxidase test, catalase test, fermentation tests,…) Lactose fermentation test Enterobacteriaceae Important clinical diseases ◻ Many parts of the body can be affected (gastrointestinal tract, urinary tract, bloodstream, central nervous system and lower respiratory tract) ◻ Salmonella typhi: Enteric fever (typhoid fever) ◻ Shigella sonnei, Shigella flexneri and Shigella dysenteriae: Bacillary dysentery (shigellosis)  Vibrio cholerae Important bacteriological features ◻ Gram-negative curved rods ◻ Vibrio shaped bacilli ◻ Halotolerant ◻ Can grow at high pH (6.5-9.0) ◻ Toxin production (+) Vibrio cholerae Important clinical diseases ◻ Cholera Electrolyte-rich diarrhea Helicobacter pylori Important bacteriological features ◻ Gram-negative spiral rods ◻ Multiple flagella at one pole ◻ Microaerophilic ◻ Urease (+) Survival in acidic environment and colonization to gastric mucus layer Helicobacter pylori Important clinical diseases ◻ Gastritis ◻ Ulcer ◻ Stomach cancers Brucella species Important bacteriological features ◻ Gram-negative coccobacilli ◻ Aerobic ◻ Intracellular  Brucella species Clinical disease ◻ Brucellosis Ingestion of the contaminated food products of animals (goats, sheep,…) Undulant fever