Gram positive cocci - IRS Batch – 17 Remya

The pneumococcus causes all of the following diseases, EXCEPT? A. Pneumonia. B. Otitis media. C. Sinusitis. D. Meningitis. E. Necrotizing fasciitis.

Gram staining appearance: G+ve cocci in pair/ diplococci G+ve cocci in pair/ diplococci Culture – Blood agar: α hemolysis (partial- green color)- mucoid α hemolysis (partial- green color)- mucoid Biochemical - Catalase: Negative NegativeOptochin: Sensitive Sensitive

A box of ham sandwiches with mayonnaise prepared by a person with a boil on his neck was left out of the refrigerator for the on-call interns. Three doctors became violently ill approximately 2 h after eating the sandwiches. The most likely cause is a. S. aureus enterotoxin b. Coagulase from S. aureus in the ham c. S. aureus leukocidin d. C. perfringens toxin e. Penicillinase given to inactivate penicillin in the pork

Certain strains of staphylococci elaborate an enterotoxin that is frequently responsible for food poisoning. Typically, the toxin is produced when staphylococci grow on foods rich in carbohydrates and is present in the food when it is consumed. The resulting gastroenteritis is dependent only on the ingestion of toxin and not on bacterial multiplication in the gastrointestinal tract. Characteristic symptoms are nausea, vomiting, abdominal cramps, and explosive diarrhea. The illness rarely lasts more than 24 h.

Gram staining appearance: G+ve cocci in cluster G+ve cocci in cluster Culture – Nutrient agar/ Blood agar: Golden yellow colonies Golden yellow colonies MSA: Media turns to yellow in color MSA: Media turns to yellow in color Biochemical - Catalase: Positive PositiveCoagulase: Positive* Positive*

“Honeymooner's" UTI Gram staining appearance: G+ve cocci in cluster G+ve cocci in cluster Culture – Nutrient agar/ Blood agar: Non hemolytic Non hemolytic MSA: Media wont change in color MSA: Media wont change in color Biochemical - Catalase: Positive PositiveCoagulase: Negative NegativeNovobiocin: Resistant* - S. saprophyticus Resistant* - S. saprophyticus

A 28-year-old menstruating woman appeared in the emergency room with the following signs and symptoms: fever, F (40 0 C); WBC, 16,000/μL; blood pressure, 90/65 mmHg; a scarlat uniform rash on her trunk, palms and soles; extreme fatigue; vomiting; and diarrhea.

A. Scalded skin syndrome. B. Toxic shock syndrome. C. Carbunculosis. D. Erysipelas. E. Impetigo. Staph or Strep ? Strep : Mainly in Strep : Mainly in immunocompromised patients

Scalded skin syndrome. FALSE: the clinical presentation and age of the patient are incorrect. Toxic shock syndrome. TRUE: the clinical presentation of TSS is an erythematous rash covering the whole body including the palms and the soles. Carbunculosis. FALSE: carbuncles present as a coalescence of furuncles and draining sinuses usually in the nape of the neck or the buttocks. Erysipelas. FALSE: erysipelas is an acute infection of the skin caused by Streptococcus pyogenes. The involved skin is inflamed and raised and clearly demarcated from the surrounding unaffected skin. Impetigo. FALSE: the clinical presentation of impetigo is one of pus-filled vesicles on an erythematous base that occur primarily on the face and limbs. The vesicles burst and are covered with a honey-colored crust.

Protein A, a determinant of pathogenesis for _______ bacteria is? A. Required for attachment to epithelial tissue. B. A superantigen. C. Binds to the Fc portion of immunoglobulin G. D. A cytotoxin. E. An exo-enzyme that aids in spreading of bacteria through tissue. Staph

A. Required for attachment to epithelial tissue. FALSE: S. aureus binds to extracellular matrix molecules using surface components recognizing adhesive matrix molecules (MSCRAMMs). B. A superantigen. FALSE: protein A is not a superantigen. C. Binds to the Fc portion of immunoglobulin G. TRUE: protein A binds to the Fc region of IgG. As a consequence the bound immunoglobulin cannot act as an opsonin, cannot fix complement, and acts to mask the bacterium. D. A cytotoxin. FALSE: protein A is not a cytotoxin. E. An exo-enzyme that aids in spreading of bacteria through tissue. FALSE: protein A is not a spreading factor like hyaluronidase.

All of the following may result from infection with GAS, EXCEPT? A. Acute pharyngitis. B. Pyoderma. C. Necrotizing fasciitis. D. Meningitis. E. Cellulitis.

A. Acute pharyngitis. TRUE: GAS is the most common bacterial cause of acute pharyngitis. B. Pyoderma. TRUE: GAS causes impetigo; often it is a mixed infection with S. aureus. C. Necrotizing fasciitis. TRUE: GAS causes necrotizing fasciitis, but so do other bacteria. D. Meningitis. FALSE: GAS does not cause bacterial meningitis. E. Cellulitis. TRUE: GAS is a common cause of skin and soft tissue infections.

Gram staining appearance: G+ve cocci in chain G+ve cocci in chain Culture – Blood agar: β hemolysis (complete- clear halo) β hemolysis (complete- clear halo) Biochemical - Catalase: Negative NegativeBacitracin: Sensitive* Sensitive* (Resistant – St. agalactiae) (Resistant – St. agalactiae)

All of the following statements about streptococcal pyrogenic exotoxins are correct, EXCEPT? A. They are superantigens. B. They are encoded by bacteriophage. C. They are responsible for the rash of scarlet fever. D. They bind IgG via the Fc region. E. They are associated with severe infections, including shock.

All of the following statements about streptococcal pyrogenic exotoxins are correct, EXCEPT? A. They are superantigens. TRUE: they function as superantigens. B. They are encoded by bacteriophage. TRUE: they are specified by bacteriophage. C. They are responsible for the rash of scarlet fever. TRUE: they cause the rash of scarlet fever. D. They bind IgG via the Fc region. FALSE: they do not bind immunoglobulin G. E. They are associated with severe infections, including shock. TRUE: M types producing Spes and capsule are associated with severe infections.

“Flesh-eating” bacteria that spread rapidly through the tissues. This necrotizing fasciitis is usually caused by a. S. aureus b. Group A streptococci c. Micrococcus d. Bacillus cereus e. Clostridium tetani

There has been a marked increase in fatal streptococcal infections including those that are described as “necrotizing fasciitis.” The strains of group A streptococci isolated have a pyrogenic exotoxin with properties not unlike those of the toxic shock toxin of S. aureus.

Exfoliative toxin EnterotoxinS.aureusS.epidermidisS.saprophyticus Food poisoning BiofilmsUTISSSSTSS

Exfoliative toxin EnterotoxinS.aureusS.epidermidisS.saprophyticus Food poisoning BiofilmsUTISSSSTSS

M protein ASO Immune complex Antibody formation Strawberry tongue Post-strep glomerulonephritis Acute rheumatic fever Anti phagocytic Scarlet fever Antibody against strep hemolytic exotoxin

M protein ASO Immune complex Antibody formation Strawberry tongue Post-strep glomerulonephritis Acute rheumatic fever Anti phagocytic Scarlet fever Antibody against strep hemolytic exotoxin

CAMP test showing the arrow-shaped zone of enhanced hemolysis (positive result) of Streptococcus agalactiae (group B) and the negative result of Streptococcus pyogenes(group A) when tested against Staphylococcus aureus.

high content of sterols 2 lipid bilayers, no PG and muramic acid Genital Mycoplasma Diene’s stain EBRB intracellular fried egg appearance Mycoplasma sp Infectious Mycoplasma hominis Chlamydia

Rocky Mountain spotted fever non-gonoccocal urethritis Ornithosis Epidemic typhus Chlamydia psittaci R. prowazekii Chlamydia trachomatis Rickettsia rickettsii