Bacterial Pathogens FINAL EXAM A survey of Human Infectious Disease Microbial Pathogens Bacterial Pathogens Cocci of medical importance Bacilli of medical importance Miscellaneous bacteria Cocci of Medical Importance Genus Staphylococcus Gram positive Common cause of skin infections Nosocomial infections Staph contributes to all categories Staph important in many categories Pneumonia 15 20 Surgical site infections 35 Urinary tract 40 o A major cause of Nosocomial infections 15 25 of all infections Staphylococcus Relevant species Staphylococcus MRSA o Staphylococcus aureus be varalent compared to others o Methicillin Resistant Staph aureus MRSA o coagulase negative Staphylococcus CoNS potentially more dangerous comes up positive on coagulase test o S aureus strain with multiple drug resistance o Resistance to methicillin o once established in a clinical setting hard to eradicate o more virulent o special procedures needed to prevent spread Staphylococcus Coagulase negative Staphylococcus o not as pathogenic as S aureus o some species normal skin inhabitants o problems with surgical sites indwelling devices skin catheter Genus Streptococcus weaker kind of microorganism Gram Positive Fastidious they require specific growth factors nutrient or vitamin o Get growth factors from animal they are living on Sensitive to many antibiotics Dies rather quickly once in the environment Major pathogens o Streptococcus pyogenes o Streptococcus pneumoniae Streptococcus Streptococcus pyogenes puss forming o Causes wide variety of disease Skin infections Reproductive tract puerperal fever got in uterus and killed fetus Strep throat starts to grow on the back of your throat Complications Rheumatic fever damaged heart valves causes complications later on in life scarlet fever disease child would get with throat infection and produces a toxin would make a bright red rash caused a high fever glomerulonephritis kidneys infected resulting in kidney failure Streptococcus Streptococcus pneumonia upper respiratory o 5 50 of persons normal nasopharynx flora o one of the main causes of pneumonia disease of the lung caused by o Pneumococcal pneumonia 70 of all bacterial pneumonia can recover with treatment most fatalities in elderly or compromised patients Streptococcus Streptococcus pneumoniae cont o Otitis media middle ear infection most common in infants sinusitis infection of the sinus in the bones around the face upper respiratory infections common cause infants young children Otitis media hard to get to middle ear to analyze so look at the outside of the ear drum 30 45 of cases due to Strep Pneumoniae with infection inflammation occurs and blistering on the ear ossicles Penicillin derivatives amoxicillin others used for treatment o 17 resistance in S pneumonia beta lactamase production multiple rounds of antibiotics to clear Surgical treatment Cocci of Medical Importance Genus Enterococcus Intestinal tract commensals Gram positive Opportunistic pathogens Important and growing cause of nososcomial infections o 16 of nosocomial UTIs o Persist for long time in environment o Have a natural resistance to many antibiotics o VRE vancomycin resistant Enterococci Cocci of Medical Importance Genus Neisseria Gram Diplococci in pairs and bean shaped Can probably only persist when on or inside an animal Does not persist in the environment most species strict pathogens some commensals pathogens are fastidious and grow best under CO2 Important species Neisseria gonorrheoae Neisseria meningitidis Genus Neisseria Neisseria gonorrheoae Gonorrhea o most common STD 400 000 cases year USA o Symptoms Males most will develop symptoms 80 Urethritis painful urination Genus Neisseria gonohorrhea Symptoms o Females commonly asymptomatic 50 urethritis vaginitis cervicitis may lead to PID pelvic inflammatory disease Treatment Gonococcal Ophthalmia Genus Neisseria o penicillin or cephalosporin tetracycline infants born to infected mothers occurrence rare due to use of antibiotic eye drops Neisseria meningitidis o meningococcal meningitis serious infection of meninges Bacterium and or endotoxin often invades the bloodstream many persons with natural immunity children teens young adults most susceptible epidemics military personnel crowded cities Genus Neisseria Symptoms o Headache stiffneck fever delirium convulsions o Disruption of blood vessels hemorrhage 15 mortality w treatment Treatment penicillin G Prevention vaccine for high risk groups epidemics prophylactic antibiotics Bacilli of Medical Importance Gram Positive o Genus Clostridium o Genus Mycobacterium Gram Negative o Pseudomonas o E coli o Genus Salmonella o Genus Yersinia Genus Clostridium Gram anaerobic spore formers many saprophytic soils water some commensals intestinal tract active fermenters some produce potent toxins FORMS OF CLOSTRIDIUM Gas Gangrene infections of serious wounds occasionally surgical sites C septicum others wounds often deep contaminated with debri dead tissue anaerobic conditions spores germinate in tissue bacterium produce o several toxins and enzymes o produce gas Gas Gangrene Treatments subcutaneous and muscle tissue killed anaerobic conditions increased bacterial growth and more tissue destroyed o broad spectrum cephalosporins penicillin o debridement scrape out all of the dead tissue in the wound o amputation o hyperbaric oxygen therapy hyper above sooo above normal oxygen levels put person in chamber where they put in extra oxygen o clean with an antibiotic Prevention o thorough cleaning of wounds o prophylactic antibiotics Tetanus C tetani wound infection and toxicosis disease due to a toxin Pathogenesis a description of the development of the disease endospore formers look like lollipops o spores invade deep puncture wounds o vegetative cells develop an produce potent toxin o exotoxin and a neurotoxin o tetanospasmin a neurotoxin o toxin travels to spinal cord o binds to inhibitory motor neurons limit the amount of impusles that reach your skeletal muscles Symptoms o painful spastic paralysis of skeletal muscles o results in tense contractions of muscles o Neck face and limbs then respiratory muscles o difficulty swallowing breathing o death due to respiratory failure o lockjaw Treatment one of the most difficult to treat o antibiotics o passive immunization human tetanus immune globulin o respiratory support o muscle relaxives Prevention o active immunization tetanus toxoid o very effective Rare in developed countries some cases in IV drug