Gram Positives Bacterias Flashcards
Bacilli
Aerobic: listeria, bacillus, corynebacterium
Anaerobic: clostridium
Cocci
Catalase +: staphylococcus
Catalase -: streptococcus
Staphylococcus
Coagulase
- positive: S. Aureus : B hemolytic
- negative : Novobiocin sensitivity :
- positive: s. Epidermidis
- negative: S. Saprophyticus
Streptococcus
HEMOLYSIS TYPE:
Alfa (partial hemolysis) : optochin sensitive: S. Pneumoniae
Resistance: S. mutans
Beta (complete) : bacitracin: sensitive: S. pyogenes (group A)
Resistance: S. agalactiae ( group B)
Gamma (no hemolysis): growth in 6.5% NaCl : group D ( enterococcus) : E.faecium, E. Faecalis
Branching filaments
Nocardia: aerobic, acid fast
Actinomycetes: anaerobic, not acid fast
Listeria monocytogenes
Bacilli gram +, intracellular rod
Acquired: deli foods , transplacenta, vaginal during delivery.
Disease: neonatal meningitis, meningitis in inmunocompromised patients, mild self limited gastroenteritis in healthy individuals.
Treatment: ampicillin + gentamicin
Dx: cold growth, blood or CSF culture.
Bacillus anthracis
Spore forming rod, gram +, anthrax toxin Types: -Cutaneous anthrax -Pulmonary anthrax Transmission: contact Diagnosis: serology+ PCR Tx: Ciprofloxacine
Cutaneous anthrax
Papule-ulcer with black eschar
Painless
Surrounded by vesicles
Pulmonary anthrax
Transmission: inhalation of spores
Flu-like symptoms that rapidly progress to fever, hemorrhage, shock
“Woolsorter’ disease”
Bacillus cereus
Fried rice , Chinese
Emetic within 1-5 hrs
Diarrheawithin 8 hrs: watery, no blood, GI pain
Corynebacterium diphtheriae
Diphtheria:
- pseudomembranous pharyngitis, lymphadenopathy , bull neck,myocarditis, arrhytmias, recurrent laryngeal nerve palsy, polyneuritis.
-Dx: Elek test +
- exotoxin: B- prophage : inhibits protein synthesis by adding ADP- ribose to eEF-2
Tx: erythromicine + antitoxin
Complications: obstruction of the airway
Clostridium tetani
TETANUS
Blocks release of GABA.
Cause: spastic paralysis, trismus, risks sardonicus.
Tx: antitoxin, diazepam and wound debridement.
Prevent: vaccination
Clostridium botulinum
Botulismo
Inhibits ACh release at the neuromuscular junction.
Causing descending flaccid paralysis.
Tx: antitoxin
Note: local Botox is used to treat dystonias, Achalasia and muscles spams. Facial wrinkles.
Clostridium perfringens
Produce Alfa toxin (lecithinase)
Myonecrosis and hemolysis due to NAGLER REACTION
Transmitted by food poisoning.
High mortality
Clostridium difficile
Pseudomembranous colitis
Often due to antibiotic use (clindamycin, ampicillin)
Cause diarrhea
Tx: metronidazole
Most common cause of neonatal sepsis
Streptococcus agalactiae (group B)
Hyppurate test +
PYR -
Bacitracin resistant
Colonize the vagina, transmitter by vaginal delivery
Tx: ampicillin with aminoglycoside
Complications of strep throat
Acute rheumatic fever
Acute glomerulonephritis
Streptococcus group A: S. Pyogenes: gram +, catalase -, bacitracin sensitive, B-hemolytic, PYR (+)
Can grow in 6.5% NaCl and bile
Enterococci
Gram positive
Case UTI, Biliary tract infections, subacute endocarditis
PYR +
Variable hemolysis
Mycobacterium tuberculosis
Primary and secondary tuberculosis
High risk patients: poverty, HIV, IV drug user
Symptoms: fever, night sweats, weight loss, chronic cough, hemoptysis.
Obligate aerobe, ACID FAST ROD, facultative intracellular, produce niacin and are catalase negative on 68C.
AURAMINE RHODAMINE STAINING
GHON COMPLEX
Transmission: respiratory droplets
Complications: miliary TB
DX: microscopy of sputum: AURAMINE RHODAMINE stain
PPD skin test
Quantiferon-TB gold standard
Slow growing (2-3 weeks) on lowestein-Jensen medium
Hansen disease
Leprosy by Mycobacterium leprosae
Acid fast rod, obligate aerobe, facultative intracellular
Immigrant patient with sensory loss in extremities
Reservoir: armadillos in Texas and lousiana
Transmission: nasal discharge
Affect skin, mucous membranes, peripheral nerves
Forms of leprosy: lepromatous and tuberculoid and borderline
Dx: punch biopsy or nasal scrapings.
Lepromine test
No cultures
Treatment: dapsone and rifampin. Dapsone profilactic for the members of family
Acid fast organisms
Mycobacteria
That means pink rods
Streptococcus of group A.
Streptococcus pyogenes
PYOGENIC: pharyngitis, cellulitis, impetigo, erysipelas.
TOXIGENIC: scarlet fever, toxic shock like syndrome, necrotizing fasciitis
INMUNO: rheumatic fever, glomerulonephritis.
GRAM +, BACITRACIN SENSITIVE, B-HEMOLYTIC, PYR (+)
Diagnosis: ASO levels /ELISA
TX: b-Lactamicos, macrolides
Most common causal agent for neonatal sepsis
Streptococcus agalactiae
GRAM (+), Bacitracin resistant, PYR (-), HIPPURATE TEST
Cause : PNEUMONIA, MENINGITIS AND SEPSIS IN BABIES DUE TO IS A NORMAL FLORA OF THE VAGINA.
TX: ampicillin + aminoglycoside
Staphylococcal toxic shock syndrome
Fever
Vomiting
Desquamation due to a scalded skin syndrome
End organ failure: hepatic failure high ast, alt, Bil,
Associated with prolonged use of vaginal tampons or nasal packing.
Rheumatic fever
Nonsuppurative sequela that occurs two to four weeks following group A pharyngitis.
Consist: migrate polyarthritis, carditis (pancarditis), chorea, erythema marginatum, subcutaneous nodules.
Jones criteria
Joint pain during 4 weeks
NAGLER reaction Or lecithinase test
Used it for diagnosis of microorganism which produce lecithinase, like clostridium perfringens.
Clostridium perfringens
High mortality
- MYONECROSIS (gas grangrene) due to Alfa toxin (lecithinase) . Dx: NAGLER reaction.
- Food poisoning due to spores which survive in undercooked food: watery diarrhea self-limiting
Clostridium difficile
Pseudomembranous colitis Toxin A and B Secondary to antibiotic use (ampicillin and clindamycin) Dx: PCR, Toxin in stools Tx: vancomycin or metronidazole
Listeria monocytogenes
- Gram + rod, aerobic, intracellular , COLD GROWTH, rocket tails
- Acquire: principal: deli foods, unpasteurized dairy products and cold deli meats . Secondary: transplacental or during birth
- cause: neonatal meningitis
- Dx: cold growth in culture agar of blood or CSF
- tx: ampicillin + gentamicin
Corynebacterium diphtheriae
- Gram+ rod, aerobic.
- Pathogenesis of Diphtheria via exotoxin encoded by beta-prophage, this exotoxin inhibits protein synthesis via ADP- ribosylation of EF-2
- Symptoms: pseudomembranous pharyngitis , lymphadenopathy, myocarditis and arrhythmias, causing bull neck and respiratory obstruction.
- Dx: + Elek test for toxin, culture in cystine- tellurite agar ( black colonies)
- Tx: Erythromicine plus antitoxin
- prevention: toxoid vaccine
Nocardia
Gram +, branching filaments , resembling fungi.
Aerobic
Acid fast
Found in soil
Cause NOCARDOSIS pulmonary infections in inmunocompromised . Cutaneous infections after trauma in inmunocompetent (cellulitis with mycetomas)
Tx: TMX-SMX
Complication: may spread to brain: multi focal abscesses.
Actinomyces
Gram +, branching filaments, anaerobic
Not acid fast
Found in normal oral, reproductive and GI flora.
Causes oral/ facial abscesses , forms yellow sulfur granules and drainage through the sinus tract.
Tx: penicillin
