Medmicro Raw Notes PDF

**MEDMICRO RAW NOTES** **Sept 20 \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--** Mircrobiome -- total collection of all genetic material of microbiota. Microbiota -- collection of all living microorganism in a particular body...

**MEDMICRO RAW NOTES** **Sept 20 \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--** Mircrobiome -- total collection of all genetic material of microbiota. Microbiota -- collection of all living microorganism in a particular body site. Group according to site. The site pertains to tissue/organs of animals where microbes are isolated. - Skin - Gastrointestinal (Gut) - Vaginal - Oral DERTO CHED -- projection -- BASILIO (Bacterial assemblage....) Lahat ng bacillus species ruminnats. The most colonized are: - Likod ng tenga - Nostril -- the portal of enrt of COVID is nasalepithelium - Mouth -- oral cavity is like mini zoo. High diversity. Bacteria (cocci, bacilli, spirali -- treponema) to fungi (yeast-candida) - Gut / colon -- bacteria are mostly facultative anerobes. The methanogens (methane producing) are colonizers of gut (archaea- small perent) - Vagina -- bacteria (lactobacilli, yeast -- candida, STRATIFIED SQUAMOES NON KERATINIZED, HALOS SAME SA MOUTH - Once ppl got older DYSBIOSIS -- imbalance of pathogenic and commensal. Pathogens \> commensal (aka normal microflora). There should be balance in healthy individuals. - Causes VAGINITIS -- inflammation of vagination - Trichomoniasis -- t. vaginalis Ideally, there should be NO PROTOZOA inside the body BUT - Entamoeba coli -- commensal. - Trichomonas tenax, entamoeba gingivalis. 10\^10 and 10\^14 times more microorganism than human cell Gene sequence -- pa isa isa Metagonimic -- kukuha ng saliva, lahat ng doon isesquence sabay sabay Skin -- Propionibacterium most in skin - Propionic acid - S. arues, epidermitis - Acne Saliva -- streptoccous mutans, salivarius, Pasterurella pestis Prevotella oris -- aasociated with periodontitis Pregnancy with severe periodontis underweight, premature aby. Dz with RA (systemic dz is associated with periodontitis) Veillonella -- gram (-) cocci Actinomycetes -- fungus like Urogenital -- lactobacilli, prevotella. Bacteriodided furmicutes F:B ratio - Furmicutes;bacteriodides - 90% Predominant phyla in gut - Use stool sample to check - Need normal ratio homeostatsti - Dysbiosis : - F\>B obesity - B\>F inflammatio in colon (IBD) inflammatory bowel dz - Kapag sumsakit tyan after kumain - Lactobacillus is notable for modifying tatio and treating obesity and IBD GUT-BRAIN AXIS - Healthy gut = healthy brain - Aytism, mentally unsrtable, they have gut dysbiosos - That's why probiotic are important - Susuceptibility diabeteic metillus - Obesity 10-100 trillion -- of microbes inside the body 10,000 species 10x many of micorbes than human cell. BALANCE GUT MIROBIOTTA - Probiotics (1 sepcesi) - Prebiotics - Synbiotic -- synergistics action of prebiotics and probiotics - Phage theraphy - Fecal transpalantion - Bacterial consortium transplantion - Consirutm -- healthy bacteria wil be administers. Nakaidentify na yung needed mo ng probiotics. Colon colonizers -- Stomach to intestine -- mas dumadami pag dumating sa colon 10\^4 10\^8 10\^12 S SI LI (colon) Cancer and ulcer is multifactorial (gene and environment) - Molecular technique to find to which genes are turned on MICROARRAY **Facultative/obligate anaerobes in colon -- WHYYYYY** **QUIZ ON MONDAY -- MICROBIAL PHYSIO (METABOLISM)** - Give chemical reaction - Identify enzyme - What pathway - Give reactant and product **September 27, 2024 \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--** ***Staphylococcus aureus*** - S. aureus -- 5^th^ implicated with nosocomial infection (1^st^ is P. aureginosa) - **Gram + cocci in cluster** - Specimen -- swab on skin, acne, boils, nasal, pimple - MSA -- mannitol salt agar - 1.5 to 2% agar for solid media - 0.4% for SIM test (gelatin like) - Phenol red = pH indicator - Review! - If sugar is fermented acid + gas - Red yellow (acid) - Red red (alkaline) - In MSA, s. aureus are yellow colonies surrounded with yellow zone. - With 7.5 NaCl - Can be used to differentiate pathogenic to non-pathogenic - Used in identification of s. aureus and enumeration (or bacterial count) from food and dairy products - Included in the BAM for detection of staphylococcal contaminants of cosmetic formulations - Bacteriological examination of water from the swimming pools and spas - Coagulase positive - Uses fresh rabbit plasma - Plasma has fibrogen which is lacking in serum - Colonies + rabbit plasma. 4hrs incubation = gel, clumping - Catalase positive -- preliminary test to differentiate strepto and staphylo - Reagent: hydrogen peroxide (use applicator stick) - Positive result: bubble formation within 2 secs - DNAse test positive - DNAse agar -- methyl green indicator - May DNA, s. aureus can release exotoxins (DNAse, type of exoenzyme) hydroluze DNA once DNA is hydrolyze, it can easily penetrate to cell wall (bacterial transformation) - From MSA colony, streak to DNAse agar positive result is clearing in DNAse Agar plate - 2 types of S. aureus - MSSA -- sensitive - MRSA -- resistance - MRSA -- methicillin resistant staph aureus - Methicillin -- type of beta-lactams - Penicillin -- oldest antibiotic (beta lactams that target the final cross bridging in newly divided cell) - Low incidence of MRSA in pH, prescribe diff antibiotic s/a vancomycin - Overdose of vancomycin: **red man syndrome** (may scalding, pamumula ng balat) - This happens bc the therapeutic and toxic dose level are close - TDM(therapeutic drug monitoring) -- taking blood sample and testing to monitor drug concentration in blood - Antibiotic stewardship -- NO OTC of antibiotic. **Disease-associated with *S. aureus*** - Impetigo (sugat na naglalangib (yellow crust) - Food poisoning - TSS -- in menstruating, associated with the use of tampon - Sudden drop of BP - Septic shock -- toxin drop of BP by bacteria - Give IV infused, 100% bioavailable - Nakaampule (glass) contains gentamycin (aminoglycoside that targets 50s ribosomes) - Walang first pass hepatic unlike yung oral **October 7, 2024 \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--** Staphylo and sptrpto -- both hemolytic Streptococcus -- Lancefield classification. Based on bacterial typing on polysaccharide component of bacteria. - It uses bacterial antigen and reacted with homologous antibody - A to S. - Most important: - Group a -- s. pyogenes. Tonsilitis, post streptocoglumeronephritis, rheumatic fever - Group B -- s. agalactiase - Group C -- zoonotic. S. equi (horses) - D -- in stool. Part of flora of large bowel other than ecoli. - Enterobacter aerogines -- enterbacteriaceae -- lactose fermenters. Gram (-) - Enterococcus faecalis-- (gram+) - F,G & L = S. anginosus - G = S. dysgalactiae - H = S. sanguis - K = S. salivanus - L = S. dysgalactiae - M & O = S. mitis - N -- Lactococcus lactis - R & S = S. suis (swine) **S. pyogenes -- group A** \- facultative anaerobe \- gram positive cocci in chain; catalase negative, coagulase negative Virulence 1. M protein -- anti-phagocytic. Cover the cell. Contradicts opsonization. 2. Hyaluronidase -- spreading factor 3. Streptodornase -- liquefy the pus, minimize abscess formation a. If may abscess, papaingest in streptokinase, dornase para lumabnaw at maging effective yung antibiotic 4. Streptokinase -- liquefy the clot b. Used as a drug for acute mycocardial infection which dissolves clot in heart and BV c. Minsan asipirin ginagamit para maging more fluid ang dugo 5. Streptolysin Oand S - O is more antigenic (used in ASO test) d. Lysis of RBC = clear zone 6. Erythrogenic/pyrogenic toxin -- carried by bacteriophage. e. If s. pyogenes is infected with phage can produce this toxin f. Erythrogenic = pamumula ng balat g. Pyrogenic = lalagnatin (pyro=fever) h. Responsible for cardinal feature of **scarlet fever**. i. Pyogenic -- pus producing. S. aureus is pyogenic laging may abscess, nana, pus. j. While s. pyogenes, it is fever producing i. When look at the tongue, strawberry olor and texture **Exotoxins of S. pyogenes** - Associated with TSS (exotoxin) - Using tampon - Asspciated w/ scarlet fever (erythrogenic toxin) **Other dz** - Pharyngitis/tonsilitis - rheumatic fever -- class 1 s. pyogenes - post streptococcal glomerulonephritis -- late consequence of infection -- class 2 s. pyogenes - Myositis -- inflammation of muscle bc of hyaluronidase - Necrotizing fasciitis - Sepsis or septicemia - Impetigo -- skin infection, yellow crust, natutuyo/nambabaalt Scarlet fever susceptibility test DICK TEST - But SHCIK TEST for C. diptheriae - Mantoux for m.tb Blood agar, - 5% sheep - Lysis of RBC is called hemolysis and is catalyzed by enzymes hemolysins - Beta hemolytic: group A and Group B (S. agalactiae. (agent of mastitis in ruminants) - Inflammation of mammary glands - CAMP TEST -- christie Atkins Much Peterson to identify group B beta hemolytic streptocci (s. agalctiae) - BA -- vertical streak (s.aureas) horizontal (uknown) 18 - Makakita ng arrowhead (positive since enhanced hemolysis)  - Alpha hemolytic -- viridians streptococci, s. pneumoniae - Optochin resistance -- viridans. Non encapsulated. - Optochin sensitive -- pneumoniae. - Optochin is antibiotic. Lagay sa gitna ng culture - NUEFELD QUELLAUNG TEST - For capsular swelling - Bile solubility -- gram+. Hydrolyze bile while viridans will not hydrolyze. - S. mutans -- tooth decay, dental plaque, periodontitis - S. mitis -- commensal of oral cavity - Gamma hemolytic -- group D (enterococcus) BILE ESCULIN HYDROLYSIS TEST -- diffentiates group d enterococci from the other grp streptocci Use Bil Esculin Agar - Blackening is positive result - Sodium azide -- inhibits growth of gram negative - Bile -- inhibit of gram (+) except enterococcus Ilagay ang antibiotic after autoclave ***Haemophilus spp*** - gram-negative coccobacilli, microaerophile  - Blood loving bacteria - Need growth factors. factor X and V - **X factor (hemin)** -- paghemolyse. needed for synthesis of cytochrome C and other iron-containing respiratory enzymes - **V factor -- NAD +** (required for reduction-oxidation (redox) processes in the cell metabolism). Produced from *S. aureus* - Grow sa chocolate agar but not on blood agar Haemophilus influenzae \| Medical Laboratories *Haemophilus spp.* Factors ------------------------ --------- *H. influenzae* X, V *H. ducreyi* X *H. aphrophilus* X *H. aegyptius* X *H. parahemolyticus* V *H. parainfluenzae* V *H. hemoglobinophilus* X - *H. influenzae* -- wrongly identify caused of flue. **Cause of meningitis in neonates in US.** - Pfeiffer's Bacillus or Bacillus influenzae - Capnophile - Facultative anaerobe - *H. ducreyi* -- soft chancre - *H*. parainfluenzae -- low pathogenicity. endocarditis, meningitis, and pneumonia and has also been recognized as a rare cause of nongonococcal urethritis - *H*. *aphrophilus* -- low pathogenicity - *H.  aegyptius* -- sore eyes, pinkeye (conjunctivitis),Brazilian purpuric fever - Sore eyes are usually viral - Pag nagmumuta, bacterial - Pag naghuhula, makati, mapula viral - If nagstart sa para = V factors - If famous na medically important = x and v. influenzae - If nalysed yung RBC ng *S. aureus* don magagrow yung *Haemophilus influenzae* - Satellitism test s one of the biochemical tests used to distinguish *Haemophilus influenzae* from other *Haemophilus spp.* - **SATELLITE PHENOMENON** -- naggogrow sa clear zone of hemolysis ng *S. aureus* in BA. - May dew point satellite colonies na naka surround sa *S. aureus*.  **Typabale *H. influenzae*** - classified on the basis of seven antigenically distinct capsular polysaccharides - "a" through "f" subtypes - The most familiar and predominant form **in H. influenzae type b (Hib)** which infects mostly children and immunocompromised - Major cause of meningitis in infants and frequently deafness and mental retardation - Type a, e and f are less common and ty c and d are rarely identified - The **Hib conjugate vaccine** is effective for protection against capsular polysaccharide type 'b' and has decreased the rate of Hib infections to a greater extent. - Meningitis, epiglottitis, cellulitis, septic arthritis, and even empyema and bacteremia. **Non typable *H. influenzae*** - Lacking polysaccharides, non-encapsulated - pneumonia, bronchitis, endocarditis, otitis media, sinusitis in patients **Tx:** resistant to beta lactam. Respond well in co -amoxiclav - Claviolanic acid -- beta lactamse inhibito - Amoxiciilin - Combination of claviolanic acid + amoxicillin ***Legionella pneumophila*** - Gram negative coccobacilli, aerobe - waterborne pathogen whose transmission was originally linked to aerosols from evaporative cooling devices - Tumutulo na tubig sa aircon, spread sa room - *L. pneumophila* can be eliminated from water supplies by hyperchlorination or by heating water to greater than 63°C. - BCYE -- buffered charcoal yeast extract **Neisseriaceae** - produce acid from CHO by oxidation Virulence factors - type IV pilin for strong attachement tissue - if N. gonorrhoeae -- urogenital - if N. meningiditis -- nasal epithelium - acquisition of iron -- utilize iron. res - resist intracellular oxidative killing - may catalase enxyme to detoxify ROS - Neisseraia resistant sa ROS dahil siya ay catalase and superoxol positive ***N. gonorrhoeae*** -- red stain coffee bean shaped, kidney shaped cocci - aka gonococcus - STD - gram negative obligate aerobe diplococcus - **causes ophthalmia neonatorum** -- blindness (be careful in culturing, if tumalsik sa mata) - PID, sterility - In oviduct, cause scarring possibility of ectopic - Fertilized egg travels to oviduct (that was previously infected) pwedeng matrap don sa scar or don sa peklat don magdedevelop - Epididymitis, prostatitis - neonates when passed thru infected birth canal - Obligate human pathogen - Inside the neutrophil or PMN pus cells. Presumptive identification. - Culture in nonselective and selective chocolate agar. - Increase of CO2 bc they are capnophile 3-7%. **USE CANDLE JAR** - Carbon dioxide generating tablet. - Another presumptive is **catalase test** - 3% h2o2 or superoxol (30% h2o2) strong bubble formation within 1-2 secs. - **OXIDASE POSITIVE -- deep purple within 10 secs** - **Bactidrop. Lagyan ng colony yung filter paper. add drop deep purple** - But Enterobacteriaceae ay OXIDASE NEGATIVE ***Neisseria meningitidis*** - diplocci gram negative encapsulated - AKA memningococcus - Cause of meningitis (but mas common pa rin ang *H. influenzae*) - Encapsulated - Healthy adults carry it on their throats and pharynx - Cultured in BA and CA with or w/o antibiotics - Ferment glucose and maltose - **WHILE *S. pneumoniae* gram positive diploccoci** - **Causes meningococcemia Waterhouse--Friderichsen syndrome** - when the bacteria *N. meningitidis* invades the blood stream. - Severe headache, stiff neck (meninges is inflamed) **Test for *N. gonorrhoeae*** - Prelim -- direct gram stain - Positive red stain in PMN - Grown non selective chocolate gar - Selective choc agar -- with antimicrobials: - **Vancomycin** -- inhibit gram + - **Colistin** -- inhibits gram - - **Nystatin** -- antifungal - **Anisomycin** -- inhibit eukaryotes - **Trimethoprim Sulfamethoxazole** -- inhibit gram (-) bacilli (bactrin na gamot na inoom pag UTI) - Kuha ng colony -- repeat gram stin - Media: Thayer-Martin, Marin-Lewis, NYC agar. - Confirmatory test - Catalase - Oxidase - PCR - Carbohydrate test -- Cystine Trypticase Agar. 1% sugar. - May series of test tubes na ibat ibang sugar - ***N. gonorrhoeae and N. meningitiditis* can ferment MALTOSE**  **Storage** - Frozen: Brain heart infusion broth 20% glycerol (cryoprotectant) - Lyophilization: 2% skim milk, liquid nitrogen. Revive for 6 years for subculturing. **Specimens** - Swab -- dacron. - Sensitivity -- 90% in urethral discharge. Urine test na unang tulo need. - Rectal swab -- yung sugat **Tx:** - **Combination therapy** - **3^rd^ gen cephalosporin** - **4^th^ gen cephalosporin** ***Kingella kinge*** - Gram negative cocci kapamilya ng nesseria - Causes endocarditis of prosthetic vavles - Frequent colonizers of young children's throaot - Septic arthritis and osteomyelitis in children +-----------------------------------------------------------------------+ | HACEK | | | | H -- Hemophilus | | | | A -- Actinobacillus | | | | C -- Cardiobacterium | | | | E -- Eikenella | | | | K - Kingella | +-----------------------------------------------------------------------+ ***Moraxella (Branhamella) catarrhalis*** - **gram-negative diplococcus that causes ear and upper and lower respiratory infections.** - Otitis media -- infection of middle ear - 30% - *S. pneumoniae* - 25% - *H. influenzae* - 15-20% - *M. catarrhalis* Comparison of *H. influenzae* and *N. meningitidis* HI NM ------------------ ---------------------------------------- -------------------- Cause meningitis Most common Less common Gram stain Gm (-) coccobacilli Gm(-) diplococci Capsule polysaccharide lipopolysaccharide **Neufeld quelling reaction positive** Three major causative agents of meningitis 1. *H. influenzae* 2. *N. meningitidis* 3. *S. pneumoniae* (implicated with otitis media) **October 9, 2024 \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--** October 14, Monday, online **Rickettsia** -- microorganism that are smaller than bacteria, size like myxovirus - **WEIL-FELIX TEST** - Usually non motile - Arthropod borne -- transmitted by insects - **Small, gram (-) coccobacilli**, not culturable on ordinary media. Need monolayer cell culture. Or embryonated egg. - WHO does not encourage cultivation of this in lab - Need lvl 2 or higher specialist - Obligate intracellular parasites. Live inside the cell (cytosol) - W/o cell they will die - In between bacteria and viruses - Two major groups - **Typhus** - **Spotted fever group** **Typhus group** - R. peowazekki - Causes epidemic typhus. - Louse-borne (human body louse) - Blood meal, then defecates, mangngati ulo scratch papasok - Same with kissing bug sa t. cruzi (chaggas dz) - Reservoid hose: humans and flying squirrel - Vector: human louse, squirrel louse/flea - **Brill-zinsser Dz** -- recrudescent typhus -- it can occur. reactivation of louse-borne typhus. - Distribution -- Africa, central and south America - Risk factor -- poor sanitation, highly populated area - Sx: high fever, pagkabigay ng antibiotic ggagaling agad. - ***R. typhi*** - If typhus -- rickettsia pero in PH context, salmonella - Zoonotic agents that causes murine or endemic typhus - Motile - Vector -- oriental rat flea - Rat / cat flea: reservoir - Sx: high fever **Spotted** - ***R. rickettsii*** -- rocky mountain spotted fever, most common and most severe - Gram negative intracellular pathogen - Organoheterotroph - Transmitted by tick bites - Humans acquire thru bites of infected tick - Lives in warm environment - Incubation -- 7 days - Sx: headache, high fever (39-40), hypotension (shock), DIC (disseminated intravascular coagulation) - Presence of minute or small clot distributed in BV. Kumakalat yung blood. (related to aneusym) - Give aspirin to liquefy the blood) - Before mycardial infection, may DIC muna before blockage of artery. - Atherosclerosis -- kakapal yung BV and brittle stiffening of artery when blood passes the passage is narrower bc of fatty deposits hypertension nawawala elasticity ng collagen puputok yung BV (before pumutok may hypertension) - Addition Sx: spotted rash are some effects with more severe cases resulting in organ damage and coma. - Rashes kasi namumuo yung dugo - Tx: doxycycline, azithromycin, treat agad after - R. conorii - R. japonica - R. akari - R. felis ***Ricketssia tsutsugamushi*** (***Orientia tsutsugamushi***) - First reported in japan by Hakuju Hashimoto in 1810 - Causes scrub typhus - Mite-borne bacterial infection - Scrub typhus occurs when infected mite larvae (chiggers) accidentally bite humans - Sx: scar-like scab **(eschar)** - An obligate intracellular parasite - Fatal if prompt doxycyline therapy is not started - Distribution -- Tsutsugamushi triangle -- Russian far east (north), Japan (east), northern Australia (south) and Afghanistan (west) DO SEROLOGICAL TEST (bacterial agglutination test) - ASO -- identify anti-streptolysin O. rheumatic fever. 1 drop serum, 1 reagent, 1-2 mins wait. Do not let dry out. - Agglutination is polystyrene bead, coated with streptolysin O. - Carrier and for better visualization - Widal -- significant titer is 80. - **Weil-felix - REVIEWWWWW** - O -- somatic form rickettsia - X = number of times subculturing was done - Ox2 - Ox19 - OxK Cultivate -- strepto, staphylo 1. subculture to NA or NB or Brain heart infusion. 2. Gram stain -- a. Gram positive cocci b. Grow in MSA (yellow colony pinhead), BA (to know hemolytic pattern) i. Catalase + - staph coagualase test ii. \- = strepto. Grow in BA (small colony pinpoint) 1. Pyogenes -- beta hemolytic 2. Agalactiae -- do CAMP test 3. Gram negatice c. EMB -- greenish ecoli. Dark center d. MCA -- pink dark, ecoli e. Klebsiella -- mucoidal, EMB, MCA f. If colorless -- IMVIC If yeast mallaki, parang grm positive but no stain B. subtulis -- malalaki na colony, Maliliit -- enteric **Chlamydia** - **C*.*** *trachomatis* - **Gram (-) cocci** - MOST COMMON STD IN REPORDUCTIVE WOMEN - Don't have signs and sx - Transmitted - Unprotected sex - Multiple partners - Transmission during pregnancy - Blood transfusion - Sx - Abdominal pain - Painful urination - Discharge - Testicular pain male - Bleeding between periods and after sexual contact - Complications - Reactive arthritis (inflamed, eyes, joints, urethra) - **Pelvic inflammatory disease ** - Sterility - Ectopic pregnancy - bc of scar on oviduct **TRACHOMA** - Chronic keratoconjunctivitis that may result blindness - Begins with normal eyes intense inflammation eyelid scarring and corneal clouding - Transmitted by droplets, touching the contaminated surface and rubbing eyes with contaminated surface - Maybe transmitted transplacentally ***C. psittaci*** - parrot fever/ornithosis - zoonotic infection - rose spot -- bacterial emboil on the skin - similar to typhoid fever (salmonella masakit tyan, 40C. same na may febrile dz) - Flat red spot on the skin - Rash of flat rose-colored spots appear on 7^th^ -12^th^ day of infection - Occur in groups of five to ten lesion on the lower chest and upper abdomen and they mor numerous following paratyphoid infection. Rose spots typically last three to four days - Sever lung infection - Meningitis - Splenomegaly -- Malaki tyan. Spleen also is an important immune organ. - High fevers, headaches, cough, dyspnea - Xray at that stage show patchy infiltrates - Cell wall less cocci - Urease (+) -- acts on urea on agar. Cherry red. Cell wall less - STD - PID - Cattle and human - Resembles *mycoplasma pneumoniae*, *m. hominis*, - Eatons agent - Urease (-) - Cattle and human - Pleuro pneumonia-like organism - Fried egg on agar - *M. pneumoniae* - low grade fever - treat with macrolides - Environmental may trigger the disappearance of cell wall ------------------- **BROCK'S NOTES** ------------------- ***Staphylococcus aureus infections*** - Staphylococci are nonsporulating, gram-positive cocci about 0.5--1.5 μm in diameter that divide in multiple planes to form irregular clumps of cell - Resistant to drying and telrate high concentration of salt (up to 10% NaCl) when grown on artificial media - Readily disperesred thru air and surfaces - Two medically important species: - S. epidermidis -- non pigmented species usually found on the skin ot mucous membrane - S. aureus -- yello pigmented - Both are present in normal microbiota of the upper respiratory tract - Staphylococcal diseases include acne, boils, pimples, impetigo, pneumonia, osteomyelitis, carditis, meningitis, and arthritis. - Many pas **PYOGENIC** (pus forming) - Virulence factors - Coagulase -- KEY VIRULENCE FACTOR. enzyme that converts fibrin to fibrinogen, forming a localized clot - Leucocidin - protein that destroys white blood cell - Certain strains cause TSS - characterized by high fever, rash, vomiting, diarrhea, and death. - The symptoms of TSS result from an exotoxin called toxic shock syndrome toxin-1. This very potent toxin is a superantigen - MSA -- selective and differential medium - 7.5% NaCl -- inhibits the growth of nonhalotorelant bacteria while allowing staphylococci to grow - Mannitol - S. aureus ferments mannitol, it generates acidity and changes the medium from red to yellow; other staphylococci, such as S. epidermidis, do not - Phenol red -- pH indicator - MRSA - Used PCR for specific identification to identify the gene mecA - gene that encodes methicillin resistance in MRSA strains **Streptococcal Syndromes** - transmitted by airborne droplets or by direct contact - are nonsporulating, homo fermentative but aerotolerant gram-positive cocci - 2 medically important: - S. pyogenes - typically grow in elongated chains - S. pneumoniae - grow in pairs or short chains, and virulent strains produce an extensive polysaccharide capsule - S. pyogenes - major species in the group A streptococci (isolated from upper respiratory tract) - M protein -- major virulence factor - streptococcal pharyngitis -- strep throat - severe sore throat with enlarged tonsils and red spots on the soft palate - tender cervical lymph nodes; and a mild fever and feeling of general malaise. - beta-hemolys -- lyses RBC - otitis media -- infection of middle ear - mastitis -- infection of mammary gland - impetigo -- infection of superficial layer of skin - Certain strains of group A streptococci carry a lysogenic bacteriophage that encodes streptococcal **pyrogenic exotoxin A** (SpeA), SpeB, SpeC, and SpeF. - These exotoxins are responsible for **streptococcal pyrogenic** **exotoxins** and **scarlet fever** - **Streptococcal pyrogenic exotoxins --** superantigens - **Scarlet fever --** **severe sore throat, fever and rash** - **Necrotizing fasciitis -** a rapid and progressive disease resulting in extensive destruction of subcutaneous tissue, muscle, and fat - **Rheumatic fever --** (autoimmune) antibodies directed against streptococcal antigens cross-react with heart valve and joint antigens, causing inflammation and tissue destruction - S. pneumoniae - Invasive lung infection - Encapsulated (s strain) s. pneumonia are very invasive - can then spread from the focus of infection as a bacteremia, sometimes infecting the bones, middle ear, and heart valves (endocarditis)