Microbiology USMLE review

Microbiology (medbullet all)

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Clostridium anerobic ( think grows in cans for botulisim)

Most Common “MOPS” strep pneumonia : 1. Meningitis adult 2. Otitis media 3. Lobar pneumonia “ community acquired” 4. Sinusitis Colon cancer endocarditis : Strep Bovis / gallolyticus GI or genital urinary surgery and then endocarditis : Enterococcus feacalis Meningitis neonate: 1. Strep agalactiae 2. E.coli 3. Listeria Monocytogenes ( why preg should avoid deli) - can lead to spontaneous abortions - granulomatosis infantiseptica Hot tube folliculitis : Pseudomonas aeruginosa Abdominal abscess : Bacteroides fragilis Osteomyelitis  Assume Staph aureus is nothing else given #1  Sickle cell : salmonella enteridis ,  Puncture foot (diabetic drug) : pseudomonas  TB : vertebral osteomyelitis ( Pott’s disease) Infectious arthritis  Neiserria gonorrhea: sexually active  Staph aureus: not sexually active or kids UTI 1. E.coli 2. Staph saprophyticus (especially for newly sexually active females) 3. Klebsiella

Information UTI  

Leukocyte esterase test = Bacterial UTI NitRITE TEST = Gram negative (convert nitrate to nitrite)

ToRCHeS  Toxoplasmosis  Others (Coxsackie B, Polio, Parvovirus B19, Listeria)  Rubella  CMV  HIV, Herpes simplex (HSV-2)  Syphilis

Rashes

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HHV-6 lace like rash Coxsackie A : palms and soles only + mouth ulcers Chicken pox : asynchronous : means not at the same stages some are vesicles, some are scabs Smallpox: was synchronous vesicles Palm and soles : “CARS” : Coxsackie A, Rickettsia, Syphilis * Rickettsia is pettichial rash, SO IS NISSERIA MENINGITIS

Special Properties Special cultures : 1. Chocolate ( have V (NAD+) and X (hemin) : haemophilus influcenza , Neisseria 2. Thayer-Martin ( Chocolate + VPN) : for N.gonorrhea select -Vancomycin: inhibit Gram (+) -Polymyxin: inhibit Gram (-) -Nystatin: fungal 3. Cholesterol: mycoplasma - Eaton’s agar: mycoplasma pneumonia 4. Salt : Staph aureus , Vibrio, Enterococci ( differentiate from strep Bovis) 5. Lowenstein-Jensen: TB slow growth 6. Bordatella Pertussis: -Regan-Lowe -Bordet- Gengou 7. Loffler’s media : Corynebacteria .diptheria ( and tellurite) 8. Thioglycolate : anerobes 9. Charcoal ( cysteine and Iron) : Legionella 10. Cysteine : Francisella, brucella, legionella, pasteurella Tick Vectors:

Ixodes tick -Borrelia burgdorferi -Babesia -Ehrlichia Dermacentor tick (dog tick) -Rickettsia -Francisella tularensis Toxins carried by Phages “COBEDS” 1. Cholera 2. Botulinum 3. DIptheria 4. Erythrogenic toxin strep pyogenes 5. Shiga toxin Definitions Viral 1. Recombination: exchange genes 2 chromosomes in homologous 2. Reassortment: segmented genomes exchanged (Influenza Pandemic) -two virsuses music infect one cell 3. Complementation: 2 viruses infect cell but one is mutated and depends on the other to replicate and survive ( Hep D depend Hep B) 4. Phenotyping mixing: two virsues infect same cells but change the coat phenotype

Weird facts         

Salmonella typhi reservoir : humans ( the gall bladder) -Salmonella enteridis : chicken and reptiles (turtles) Gardnerella vaginalis : Vaginosis , clue cell ( with bacteria around epithelial cell) Ehrlichia : similar to Rocky mountain spotted fever except here theres no rash Norcardia mimics TB but creating lung cavity too ( also acid fast stain weak, but these are BRANCHING) EHEC : shiga like toxin, no invasion BLOODY o EIEC: shiga like with invasion , BLOODY  Shigella: invasion and shiga toxin to 60S ribosome : bloody Pork + unpasteurized milk : Yersinia Beef undercooked, petting zoo : EHEC Chicken, unpasteurized milk : Campylobacter Chicken, reptiles (turtle) : Salmonella Unpasteuzied dairy : Brucella

Meningitis:  HSV-1 classic for encephalitis (temporal perivenular)  HSV-2 classic for meningitis  Aspectic meningitis is one cause by NOT BACTERIA (without stupor and meningeal irritation) STD  Chlamydia trachomatis - Have elementary body and reticular bodies (replicating) 1. Chlamydia : D-K serotypes “DKNY” 2. Lymphogranuloma Venerum : L1-L3

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HIV   

Hepititis B Gardnerella vaginalis, trichomonas vaginallis

Brain abscess : ring enhanced lesions = TOXOPLASMA Gondii Diarrhea : cryptosporiDium Eye retinitis: CMV “ cotton wool spots”

Questions 

Leigonella: diagnosed by urine antigen test , culture on charcoal agar ( with cysteine and iron) - suspect if high fever + WATERY DIAHREA + neutropenia  Haemophilus influenza - epiglottitis - PRP capsule : polyribosyl-ribitol-phosphate  Bacillus anthracis; malignant pustule (painless ulcer with black center and local edema) -capsule made of PROTEIN instead of polysaccharide ( D-glutamate)  Give vaccine strep pneumonia to 1. HIV 2. Asplenic 3. COPD 4. Immunosuppressed  Hepatitis B vaccine : RECOMBINANT surface protein  Inactivated toxin vaccine : DTP : diphtheria, tetanus, Pertussis  Aspergillus Fumigatus : cause allergic bronchopulmoary aspergilliosis : high IgE and eosinophils 1. Colonizing aspergillosis: old lung cavities, form fungal balls in people with TB, emphysema sarcoidosis 2. Hypersensitivity: allergic bronchopulomary aspergillosis in people with asthma 3. Invasive Aspergillosis: immunosuppressed and neutropenic patients

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EBV:

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-Heterophil antibiodies SPECIFIC (monospot test) -EBV encode oncogenes cause high proliferation B cells (still secrete Ig) Tzank Smear : HSV-1 and 2, and 3( varicella) Staph makes yellow pigment

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Most common source E.coli bacteremia is catheter Receptors bind to 1. CMV : Integrins 2. EBV : CD21 3. HIV CD4 + CCR5 and CXCR4 4. Rabies: nicotinic acetylcholine 5. Rhinovirus : ICAM1 (CD54) Toxoplasmosis:  Hydrocephalus, calcifications intracranial, chorioretinits  Part of Torches therefore go across placenta ( in-utero infection) Intrapartum (during birth) -HSV -chlamydia and gonorrhea: neonatal conjunctivitis -strep agalactiae Neisseria are facultative intracellular therefore can be seen in PMN Arthritis  Septic: asymmetric polyarthralgia ( N.gonorrhea)  Rheumatic fever : migratory polyarthritis Cryptococcus neoformans  Acquired via inhalation  Yeast form only : narrow based buds  Pigeon dropping  Diagnose: , latex agglutination CSF CNS lymphoma are B cell origin Lyme disease : bells palsy bilateral Haemophilus without capsule , vaccine wont work Rubella : POSTAURICULAR AND OCCIPITAL LYMPHADENOPATHY Exanthem subitum/ roseola infantum Clostridium perfringens : causes 1) gas damage tissue 2) food poisoning watery Candida normal part of flora in the mouth and GI. Mycoplasma causes the immune system to also attack own RBC causing anemia . these cross react with RBC : leading to cold agglutinin Intracellular : chlamydia, rickettsia, gonorrhea, Salmonella Transduction

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1) Generalized: during LYTIC, random bacterial genes accidentally packaged 2) Specialized: during LYSOGENIC , select bacterial genes The (+) ss RNA does the polycistronic to monocystronic by POLYPROTEIN CLEAVED BY PROTEASE Campylobacter cant survive in alkaline whereas vibrio can GI infection NO WBC IF DON’T INVADE MUCOSA Phospholipase C/ lecithinase is degraded by clostridium perfrigens No 3’-5’ proof reading in viruses Cold agglutinin: mycoplasma, EBV, and blood malignancy Catalase (+) : serratia, nocardia, aspergillus o PLACESS o Pseudomonas o Listeria o Aspergillus o Candida o Enterobacteriacea o Staph aureus o Serratia EHEC DOESN’T FERMENT SORBITOL (ONLY ONE) PYR ( pyrrolidonyl arylamidase) + is strep pyogenes Rotavirus has 10-11 segments therefore can undergo genetic reassortment like influenza Clostridium difficle does damage by CYTOSKELETON DAMAGE Mucormycosis: mucor, Rhizopus, Absidia Serpetile growth of TB is due to CORD FACTOR which correlated with virulence by inhibiting PMN , mitochondria destruction and release TNF Neonatal rubella: 1. Cataract 2. Microcephally mental retardation 3. Deafness 4. PDA or pulmonary stenosis Fungi 1. Immune low: candida, aspergillosis, mucormycosis 2. Antibiotic use: Candida oral and vagina 3. Animal: microsporum canis= tinea capitis 4. Bats or pigeon near Ohio and Mississippi: Histoplamosis capsulatum 5. Thorn prick: sporothix schenckii Necrotizing Fasciitis : 1. Strep pyogenes 2. Staph aureus 3. Clostridium perfringens E.coli Virulence factor

Mechanisim

Presentation

LPS K1 capsular polysaccharide Verotoxin/ shiga like Head stable/liable enterotoxin P fimbriae

IL-1, 6 and TNF-alpha release from macrophage Prevent phago and complement Inactivate 60S Fluid and electrolyte sectetion Allow adhesion to urothelium

Bacteremia and shock Neonatal meningitis Gastroenteritis bloody Gastroenteritis watery UTI