Gram Positives Bacterias

Question 1

Bacilli

Answer 1

Aerobic: listeria, bacillus, corynebacterium

Anaerobic: clostridium

Question 2

Cocci

Answer 2

Catalase +: staphylococcus

Catalase -: streptococcus

Question 3

Staphylococcus

Answer 3

Coagulase

• positive: S. Aureus : B hemolytic
• negative : Novobiocin sensitivity :
  - positive: s. Epidermidis
  - negative: S. Saprophyticus

Question 4

Streptococcus

Answer 4

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

Question 5

Branching filaments

Answer 5

Nocardia: aerobic, acid fast

Actinomycetes: anaerobic, not acid fast

Question 6

Listeria monocytogenes

Answer 6

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.

Question 7

Bacillus anthracis

Answer 7

Spore forming rod, gram +, anthrax toxin 
Types: 
-Cutaneous anthrax 
-Pulmonary anthrax 
Transmission: contact
Diagnosis: serology+ PCR
Tx: Ciprofloxacine

Question 8

Cutaneous anthrax

Answer 8

Papule-ulcer with black eschar
Painless
Surrounded by vesicles

Question 9

Pulmonary anthrax

Answer 9

Transmission: inhalation of spores
Flu-like symptoms that rapidly progress to fever, hemorrhage, shock
“Woolsorter’ disease”

Question 10

Bacillus cereus

Answer 10

Fried rice , Chinese

Emetic within 1-5 hrs
Diarrheawithin 8 hrs: watery, no blood, GI pain

Question 11

Corynebacterium diphtheriae

Answer 11

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

Question 12

Clostridium tetani

Answer 12

TETANUS

Blocks release of GABA.

Cause: spastic paralysis, trismus, risks sardonicus.
Tx: antitoxin, diazepam and wound debridement.
Prevent: vaccination

Question 13

Clostridium botulinum

Answer 13

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.

Question 14

Clostridium perfringens

Answer 14

Produce Alfa toxin (lecithinase)
Myonecrosis and hemolysis due to NAGLER REACTION
Transmitted by food poisoning.

High mortality

Question 15

Clostridium difficile

Answer 15

Pseudomembranous colitis

Often due to antibiotic use (clindamycin, ampicillin)
Cause diarrhea
Tx: metronidazole

Question 16

Most common cause of neonatal sepsis

Answer 16

Streptococcus agalactiae (group B)

Hyppurate test +
PYR -
Bacitracin resistant

Colonize the vagina, transmitter by vaginal delivery

Tx: ampicillin with aminoglycoside

Question 17

Complications of strep throat

Answer 17

Acute rheumatic fever

Acute glomerulonephritis

Streptococcus group A: S. Pyogenes: gram +, catalase -, bacitracin sensitive, B-hemolytic, PYR (+)

Question 18

Can grow in 6.5% NaCl and bile

Answer 18

Enterococci

Gram positive
Case UTI, Biliary tract infections, subacute endocarditis
PYR +
Variable hemolysis

Question 19

Mycobacterium tuberculosis

Answer 19

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

Question 20

Hansen disease

Answer 20

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

Question 21

Acid fast organisms

Answer 21

Mycobacteria

That means pink rods

Question 22

Streptococcus of group A.

Streptococcus pyogenes

Answer 22

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

Question 23

Most common causal agent for neonatal sepsis

Answer 23

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

Question 24

Staphylococcal toxic shock syndrome

Answer 24

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.

Question 25

Rheumatic fever

Answer 25

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

Question 26

NAGLER reaction Or lecithinase test

Answer 26

Used it for diagnosis of microorganism which produce lecithinase, like clostridium perfringens.

Question 27

Clostridium perfringens

Answer 27

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

Question 28

Clostridium difficile

Answer 28

``` Pseudomembranous colitis Toxin A and B Secondary to antibiotic use (ampicillin and clindamycin) Dx: PCR, Toxin in stools Tx: vancomycin or metronidazole ```

Question 29

Listeria monocytogenes

Answer 29

* 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

Question 30

Corynebacterium diphtheriae

Answer 30

* 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

Question 31

Nocardia

Answer 31

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.

Question 32

Actinomyces

Answer 32

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