Bacterial Pathogens (FINAL EXAM)A survey of Human Infectious DiseaseMicrobial PathogensBacterial PathogensCocci of medical importanceBacilli of medical importanceMiscellaneous bacteriaCocci of Medical ImportanceGenus StaphylococcusGram positiveA major cause of Nosocomial infections15-25% of all infectionsCommon cause of skin infectionsNosocomial infectionsStaph contributes to all categoriesStaph important in many categoriesPneumonia- 15-20%Surgical site infections- 35%Urinary tract-40%StaphylococcusRelevant species:Staphylococcus aureus- be varalent compared to othersMethicillin Resistant Staph. aureus (MRSA)coagulase negative Staphylococcus (CoNS)- potentially more dangerous (comes up positive on coagulase test)StaphylococcusMRSAS. aureus strain with multiple drug resistanceResistance to methicillinonce established in a clinical setting hard to eradicatemore virulentspecial procedures needed to prevent spreadStaphylococcusCoagulase negative Staphylococcusnot as pathogenic as S. aureussome species - normal skin inhabitantsproblems with:surgical sitesindwelling devices (skin catheter)Genus Streptococcus- “weaker” kind of microorganismGram PositiveFastidious- they require specific growth factors (nutrient or vitamin)Get growth factors from animal they are living onSensitive to many antibioticsDies rather quickly once in the environmentMajor pathogensStreptococcus pyogenesStreptococcus pneumoniaeStreptococcusStreptococcus pyogenes (puss forming)Causes wide variety of diseaseSkin infectionsReproductive tract (puerperal fever)- got in uterus and killed fetusStrep throat- starts to grow on the back of your throatComplicationsRheumatic 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)StreptococcusStreptococcus pneumonia upper respiratory5-50% of persons - normal nasopharynx floraone of the main causes of pneumoniadisease of the lung caused byPneumococcal pneumonia~ 70% of all bacterial pneumoniacan recover with treatmentmost fatalities in elderly or compromised patientsStreptococcusStreptococcus pneumoniae (cont.)Otitis media(middle ear infection)(most common in infants), sinusitis(infection of the sinus in the bones around the face), upper respiratory infectionscommon cause - infants, young childrenOtitis media- hard to get to middle ear to analyze so look at the outside of the ear drum30-45% of cases due to Strep. Pneumoniaewith infection- inflammation occurs, and blistering on the ear ossiclesPenicillin derivatives (amoxicillin, others) used for treatment17% resistance in S. pneumonia (beta-lactamase production)multiple rounds of antibiotics to clearSurgical treatmentCocci of Medical ImportanceGenus EnterococcusGram positiveIntestinal tract commensalsOpportunistic pathogensImportant and growing cause of nososcomial infections(~16% of nosocomial UTIs)Persist for long time in environmentHave a “natural” resistance to many antibioticsVRE (vancomycin resistant Enterococci)Cocci of Medical ImportanceGenus NeisseriaGram (-)Diplococci – (in pairs) and bean-shapedCan probably only persist when on or inside an animalDoes not persist in the environmentmost species - strict pathogens, some commensalspathogens are fastidious and grow best under CO2Important speciesNeisseria gonorrheoaeNeisseria meningitidisGenus NeisseriaNeisseria gonorrheoaeGonorrheamost common STD - 400,000 cases/year USASymptomsMales:most will develop symptoms (80%)Urethritis painful urinationGenus Neisseria (gonohorrhea)SymptomsFemalescommonly asymptomatic (50%)urethritis, vaginitis, cervicitismay lead to PID (pelvic inflammatory disease)Treatment:penicillin or cephalosporin+tetracyclineGonococcal Ophthalmiainfants born to infected mothersoccurrence rare due to use of antibiotic eye dropsGenus NeisseriaNeisseria meningitidis -meningococcal meningitisserious infection of meningesBacterium and/or endotoxin often invades the bloodstreammany persons with natural immunitychildren/teens/young adults most susceptibleepidemics - military personnel, crowded citiesGenus NeisseriaSymptomsHeadache, stiffneck, fever, delirium, convulsionsDisruption of blood vessels - hemorrhage15% mortality w/treatmentTreatment: penicillin GPrevention: vaccine for high risk groups, epidemics, prophylactic antibioticsBacilli of Medical ImportanceGram PositiveGenus ClostridiumGenus MycobacteriumGram NegativePseudomonasE. coliGenus SalmonellaGenus YersiniaGenus ClostridiumGram (+) anaerobic, spore-formersmany saprophytic; soils, watersome commensals; intestinal tractactive fermenterssome produce potent toxinsFORMS OF CLOSTRIDIUM:Gas GangreneC. septicum, othersinfections of serious wounds, occasionally surgical siteswounds often deep, contaminated with debridead tissue anaerobic conditions spores germinate in tissuebacterium produce:several toxins and enzymesproduce gasGas Gangrenesubcutaneous and muscle tissue killed anaerobic conditions increased bacterial growth and more tissue destroyedTreatmentsbroad spectrum cephalosporins, penicillindebridement- scrape out all of the dead tissue in the woundamputationhyperbaric oxygen therapy- hyper=above sooo above normal oxygen levelsput person in chamber where they put in extra oxygenclean with an antibioticPreventionthorough cleaning of woundsprophylactic antibioticsTetanusC. tetaniwound infection and toxicosis- disease due to a toxinendospore formers (look like lollipops)Pathogenesis (a description of the development of the disease)spores invade deep puncture woundsvegetative cells develop an produce potent toxinexotoxin and a neurotoxintetanospasmin - a neurotoxintoxin travels to spinal cordbinds to inhibitory motor neurons- limit the amount of impusles that reach your skeletal musclesSymptomspainful spastic paralysis of skeletal musclesresults in tense contractions of musclesNeck, face and limbs then respiratory musclesdifficulty swallowing, breathingdeath due to respiratory failure“lockjaw”Treatment- one of the most difficult to treatantibioticspassive immunization - human tetanus immune globulinrespiratory supportmuscle relaxivesPreventionactive immunization - tetanus toxoidvery effectiveRare in developed countries - some cases in IV drug usersCommon in developing nationsespecially neonatal umbilical stump infections- then the infant comes down with tetanusBotulismC.