#6 bacteria notes (1).docx
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Bacteria FSED 227 – MICROBIOLOGY IN FUNERAL SERVICE Gram positive cocci staph & strep staphylococcus aureus Most virulent species of Staph Normal flora (colonizers) of Skin Mucus membranes Routes of infection Trauma/abrasion (enter normally sterile site) Person-to-person Nosocomial Ingesti...
Bacteria FSED 227 – MICROBIOLOGY IN FUNERAL SERVICE Gram positive cocci staph & strep staphylococcus aureus Most virulent species of Staph Normal flora (colonizers) of Skin Mucus membranes Routes of infection Trauma/abrasion (enter normally sterile site) Person-to-person Nosocomial Ingestion of bacteria or toxin Staph. aureus Virulence Factors Enzymes – help infection to easily spread Cytolytic toxins – hemolysins and leucocidins Protein A – antiphagocytic Enterotoxins – heat-stable, cause diarrhea and vomiting Staph. aureus Infections Skin and wound infections are typically suppurative (puss filled) and surrounded by necrotic tissue Folliculitis – inflammation of hair follicle or oil gland Furuncles - boils, superficial Carbuncles - large more invasive lesions, develop from multipe furuncles Impetigo (blisters)– large pustules, very contagious Food poisoning Enterotoxins - pre-formed, ingested, heat-stable Nausea, vomiting, cramping begin in 1-8 hours Diarrhea and headache also common Scalded Skin Syndrome – most common in children < 5 years old Exfoliative toxin – skin peals off in sheets Distant infection, lesion Toxic Shock Syndrome TSST-1 enterotoxin – causes low blood pressure Pneumonia, septicemia, osteomyelitis Portal of entry – mouth or skin Portal of exit – saliva or skin exudates Gram Positive cocci – streptococcus pyogenes Routes of infection (transmission) Person-to-person via contaminated respiratory droplets or secretions Colonizes upper respiratory tract Carrier state NOT normal flora Clinically significant if found treat the infection Also referred to as Group A Strep Beta hemolytic Strep. Pyogenes – virulence factors M protein - antiphagocytic & aid attachment Streptolysin O (oxygen labile) – hemolysin Streptolysin S (stable in O2) – hemolysin DNase – degrades DNA Streptokinase – plasminogen to plasmin Hyaluronidase – degrades connective tissue Spreading factor Erythrogenic toxin - produces rashes Strep. Pyogenes infections Localized Acute pharyngitis/tonsillitis (strep throat) one of the most common bacterial infections acquired from inhalation On rare occasion extensive spreading occurs leading to pneumonia, meningitis, or bacteremia (Jim Henson) Major problem = nonsuppurative sequelae Erysipelas – a form of cellulitis Red raised rash Impetigo Non-suppurative sequelae – these are not infections Rheumatic fever Only follows respiratory infections with Group A Strep Fever & inflammation of joints, heart, CNS, sub-Q tissues Acute glomerulonephritis Follows respiratory or cutaneous Group A infections Edema, hypertension, hematuria, proteinuria, rarely leads to renal failure Systemic Necrotizing fasciitis (flesh-eating bacteria) Puerperal sepsis or fever – childbirth or abortion Toxin mediated Scarlet fever Streptococcal toxic shock syndrome Portal of entry – mouth or skin Portal of exit – saliva and respiratory droplets/aerosols or skin exudates Gram Positive cocci – streptococcus pneumoniae Major cause of pneumoniae & meningitis With or without bacteremia Lobar pneumonia – affects entire lobe of lung Sinusitis, otitis media Transmission: Person-to-person (colonizes nasopharynx) Aspiration into lower respiratory tract leads to pneumonia Normal flora of respiratory tract Alpha hemolytic Virulence factor Capsule – over 90 serotypes based on capsule Some more severe than others Portal of entry – nose and mouth Portal of exit – saliva respiratory droplets and aerosols Gram negative diplo cocci - Neisseria Epidemiology - Neisseria Most are normal flora of respiratory tract and urogenital tract EXCEPTIONS!! Neisseria gonorrhoeae AKA GC Neisseria meningitidis AKA MC Routes of infection Person-to-person Neisseria gonorrhoeae Only found in humans Transmitted sexually and during vaginal delivery Infects epithelial cells Urethra, endocervix, anorectal, pharynx, conjunctiva Usually remains localized, but can disseminate (severe disease) Transmitted by close contact or congenital Virulence Factors Capsule – inhibits phagocytosis Pili – aids attachment Gonorrhea: Infection Male Male urethritis Purulent discharge Dysuria Complications: Prostatitis Epididymitis Female Vaginal discharge, bleeding Dysuria, lower abdominal pain 50% may be asymptomatic Untreated – PID, sterility, ectopic pregnancy Gonorrhea: Disseminated Infections Via blood 1% of infections Purulent arthritis Gonorrhea : Infant Infections Ophthalmia neonatorium Eye infection Can lead to blindness Every newborn’s eyes treated w/in 1 hr of birth Required by law in U.S. Usually erythromycin Portal of entry – eyes, genitals or any mucus membrane Portal of exit – vaginal secretions, semen, exudates Neisseria meningitidis Can be found in oro/nasopharynx of 3-30% asymptomatic individuals (carriers) Major cause of fatal bacterial meningitis in young adults Epidemics – dormitories, barracks Less common cause of s epticemia (meningococcemia), conjunctivitis, pneumonia Virulence Factors Pili (adherence) Capsule (inhibits phagocytosis) Encapsulated strains associated with epidemics Endotoxin (fever, shock) Transmitted via airborne respiratory droplets Meningitis = Abrupt onset of frontal headache, stiff neck, and sometimes fever Meningococcemia May occur with or without meningitis 25% mortality even with treatment Petechiae, septic shock, DIC, death Waterhouse-Friderichsen syndrome Hemorrhaging into adrenal glands Portal of entry – mouth and nose Portal of exit – respiratory droplet and aerosols Family Enterobacteriaceae – gram negative rods A.K.A. enterics Most are normal inhabitants of the GI tract Exceptions: Salmonella, Shigella, Yersinia, and certain strains of E. coli These are never considered normal flora Most are motile and have a __________________ Exceptions: Klebsiella, Shigella, Yersinia @ body temp Virulence Factors Hemolysins – some strains produce proteins that lyse RBC’s (b-hemolysis on BA) Capsules – (esp. Klebsiella) antiphagocytic Pili – allow attachment to epithelial cells Toxins Endotoxin – part of cell wall DIC, fever Exotoxin/enterotoxin - secreted as organism grows Are generally associated with gram+ Exotoxins of enteric Gram-’s are classified as enterotoxins because they are directed against the GI tract salmonella Currently only 2 species divided into over 1700 subspecies and serotypes S. enterica & S. bongori Cause infection in man & animals Animals may serve as reservoir esp fowl and cold-blooded animals Spread person to person, fecal-oral, contaminated food and water Virulence Factors Enterotoxin Resist stomach acid Can disseminate High infective dose Salmonella Enterocolitis – Inflammation of mm of small and large intestine Most common form of Salmonella disease referred to as food poisoning Associated with strains found in animals Organisms invade mucosa of small & large intestine – usually remain localized 8 – 36 hours after ingestion = nausea, headache, vomiting, profuse diarrhea, low grade fever Self-limiting 2 – 7 days Salmonella - Bacteremia Caused by non-typhoidal Salmonella that spread from GI tract Prolonged fever with intermittent bacteremia May result in metastatic infection of bones, joints, meninges, or cardiovascular system Salmonella – Enteric Fevers Most commonly caused by S. Typhi Typhoid fever No known animal reservoir Other types similar but less severe Begin as inflammation of intestine followed by invasion of lymph nodes – lymphatic system – blood – organs & tissues Multiplication in skin = rose spots Fever, headache, loss of appetite, weakness, splenomegaly, abdominal pain Life threatening disease Organisms eventually invade gall bladder Salmonella –Carrier State Follows enteric fever or septicemic forms Organisms become lodged in biliary tract and gall bladder Resistant to bile No symptoms but excrete organism is stool for weeks to years Prolonged carrier state – remove G.B. (Cholecystectomy) Portal of entry – mouth Portal of exit – feces Shigella True intestinal pathogen No animal reservoir – man only source Person-to-person, fecal oral 4 species all non-motal S. flexneri – S. sonnei – most common US isolate S. boydii S. dysenteriae – most severe 1000X more Shiga toxin All cause dysentery Necrosis, ulceration, & inflammation of large intestine; watery diarrhea with mucus, blood, pus; cramps. Shigella Dysentery #1 organisms attach to mucosal surface #2 they penetrate intestinal epithelial cells #3 they multiply elaborating shiga toxin that kills absorptive cells Result=inflammation, shedding of intestinal lining, and ulcer formation Symptoms=high fever, chills, abdominal cramps Inflammation response of PMN’s and macarophages resulting in the mucopurulent stool Highly contagious Low infective dose Rarely penetrate and disseminate Severe complications Escherichia coli Most commonly isolated Enterobacteriaceae Normal flora of GI Gastrointestinal infections Ingestion of contaminated food/water (fecal/oral) Ingestion of undercooked beef, raw milk Extraintestinal infections Endogenous spread Person-to-person (nosocomial) Escherichia coli intestinal infections Enteropathogenic (EPEC) Associated with children under 2 Day care centers and hospital nurseries Disease production poorly understood Fever, malaise, vomitting, diarrhea w/mucus but no blood Enterotoxigenic (ETEC) Traveler’s Diarrhea High infective dose – 106 – 1010 organisms Self-limiting with watery diarrhea, nausea, abdominal cramps, low-grade fever No mucosal penetration Eneroinvasive (EIEC) Illness caused similar to Shigella Dysentery with penetration, invasion, and destruction of intestinal mucosa and stools may contain blood and mucus. Enterohemorrhagic (EHEC) – O157:H7 Undercooked beef, raw milk, apple cider, and bean sprouts have all been implicated Hemorrhagic diarrhea & colitis Produces toxin Identical to Shigella Escherichia coli extra-intestinal infections UTI – one of most common causes Pili allow adherence to urinary tract even when urine is flowing Common nosocomial Meningitis – newborn/ encapsulated strain K1 capsular antigen identical to N. mening Gp B Most common cause of gram- sepsis Klebsiella pneumoniae Normal flora in intestine Does NOT produce intestinal disease Opportunistic pathogens – compromised host Capsule often present in virulent strains Most common infections: UTI & pneumonia 3% bacterial pneumonia due to K. pneumoniae Commonly nosocomial infections Klebsiella normal in upper resp tract of 5% of population Proteus spp. Normal intestinal flora – opportunistic pathogen Nosocomial infection Common cause of UTI and wound infection Proteus produces swarming colonies – film of confluent growth Most common isoloates P. mirabilis & P. vulgaris Yersinia pestis Causes plague Transmitted via Rat flea bites Airborne droplets (pneumonic plague) Ingestion of contaminated animal tissue Highly virulent organism Antiphagocytic capsule Exotoxins, coagulase, fibrinolysin On A list of bioterrorism agents Report recovery of Y. pestis to public health authorities Optimal growth @ 25 – 30 degreesC Not motile at 35 degreesC Most are motile at room temp 25 degreesC Bubonic plague Acute febrile disease Lesion in lymph node that drains; painful buboes develope Septicemia develops (3-6 days) Mortality nearly 100% (Streptomycin = drug of choice) Pneumonic plague Transmitted by infectious droplets Sneezing, coughing Malaise and pulmonary signs Rapidly fatal (Streptomycin = drug of choice) Other gram-negative rods Vibrio cholerae Curved gram-negative rod Found in water NOT normal flora Transmission Ingestion of contaminated water/seafood Exposure of broken skin/mm to water Mild gastroenteritis to cholera Simple wound infections to fatal septicemia Associated with Recent consumption of raw seafood (oysters) Recent immigration or foreign travel Accidental trauma during contact with fresh or salt water (fishhooks, shellfish) Toxigenic strains O1 and O139 Associated with epidemics and pandemics of cholera Spread mainly by contaminated water or improperly prepared food (fecal/oral) Acute, severe gastroenteritis, vomiting, profuse watery diarrhea; 10-30 rice water stools per day Cholera toxin (choleragen) Causes mucosal cells to hyper secrete water and electrolytes = severe dehydration and death Organism does not penetrate mucosal barrier (no inflammatory cells seen; unlike dysentery Non 01and 0139 Produces no toxin Milder form of gastroenteritis Extraintestinal infections Ear infections Cellulitis Septicemia
