الفصل الثاني

Question 1

What are the staph. aureus disease?

Answer 1

1. Surgical wound’s infection, the abscesses in many organs
2. Endocarditis
3. Gastroenteritis (food poisoning).

Question 2

What are the Characteristics of staph. Aureus ?

Answer 2

Gram-positive cocci arranged in clusters, some single cells, pairs and
short chains , non- flagellated , non -motile and non -spore forming,
aerobic and facultative anaerobic .

Question 3

What are the virulence factors of the staph . Aureus ?

Answer 3

 Produce catalase and coagulase enzymes.
 Potent toxins including (Alpha, beta, gamma and dalta) toxins act
on host cell membrane, and produce enterotoxins.

Question 4

What are the treatments used for staph.aureus disease?

Answer 4

-penicillin and cephalosporins

 In beta –lactamases “penicillinase “ producing strains ( resist to
penicillin ), (Methicillin, Nafcillin ,Oxacillin )

Question 5

What Are the stap.epidermids diseases ?

Answer 5

 Endocarditis on prosthetic heart valve
 Prosthetic hip infection and
 Neonatal sepsis.

Question 6

What are the Characteristics of the staph. Epidermids ?

Answer 6

Gram-positive cocci arranged in clusters, some single cells, pairs and
short chains , non- flagellated , non -motile and non -spore forming,
aerobic and facultative anaerobic . And coagulase negative.

Question 7

What are the virulence factors of the staph. Epidermids?

Answer 7

 Produce biofilm which enhance organism adhesion to the surface
of the foreign body and to multiply there. This biofilm completely
cover the bacteria and protect it from the antimicrobial agent and the host defence mechanism

Question 8

What are the treatments used for staph. Epidermids diseases ?

Answer 8

Vancomycin plus either rifampin or an aminoglycoside.

Question 9

What are the diseases that caused by strept. Pyogens?

Answer 9

Streptococcal infections may be localized i.e. acute pharyngitis and
skin infections or
 Systemic (involvement of deeper tissue and organs) such systemic
infection are life threatening.

Question 10

What are the virulence factors of the strept. Pyogens ?

Answer 10

 protein –F and protein M which aids in the attachment to host
cells.
 Streptolysin O, Streptolysin S toxins and
 streptococcal pyrogenic exotoxins mediate production of rash
(i.e. scarlet fever ) or multisystem effects that may result in death.
 They were catalase – negative.

Question 11

What are the characteristics of strept. Pyogens?

Answer 11

Gram-positive spherical to ovoid cells in chains of short to medium
length (4 to 10 cells)

Question 12

What are the treatments for strept. Pyogens diseases?

Answer 12

Penicillin. ,
Other penicillins, cephalosporins, and tetracyclines are also active
against Strept. .
Patients allergic to penicillin are usually treated with erythromycin.

Question 13

What are the diseases caused by strept. Pneumonia?

Answer 13

 pneumonia and meningitis in adult and

 Otitis media and sinusitis in children .

Question 14

What are the characteristics of the strept. Pneumonia?

Answer 14

Gram-positive, lancet- shape cocci , occur in pairs (diplococci ) or short
chain .

Question 15

What are the virulence factors of strept. Pneumonia?

Answer 15

 Pneumococcal polysaccharide capsule retards phagocytosis .

 Produce pneumolysin and neuraminidase .

Question 16

What is the treatments used for strept . Pneumonia diseases? And the prevention?

Answer 16

Penicillin G

Vaccine contain capsular polysaccharide most frequently given for
patients older than 65 years or given to patients with compromised
immune system.

Question 17

———-used in gaseous form for sterilizeing heat senstive objects

Answer 17

Ethylene oxide

Question 18

————kill spores in 3 to 10 hours ,used to sterlize medical equipments

Answer 18

Gluteraldehyde

Question 19

Numerate the physical methods of strilization ?Write uses for three

Answer 19

1-incineration -treat infectious waste burned to ashes at 870-980 c
2-moist heat -autoclave 121c for 15-20 m used for media and liquids
3-dry heat - oven for 1.5 to 3 hours at 160-180C for glassware ,oil,poders
4-filtration -for heat senstive objects (antibiotics solution ,toxic ,chemicals,vaccines)
5-ionizing radiation -used for disposibeles such as plastic syringes and cloves before use

Question 20

Compare between sterlization and disinfection ?

Answer 20

Sterilization: Killing or removal of all living organisms (including spores)
from particular location or material
Disinfection: is killing of many but not all microorganisms, and the
bacterial spores may survive.

Question 21

Numerate physical methods of disinfection ?

Answer 21

1-boiling- at 100C for 15m. Whitch kills vegetative bacteria
2- pasteurizing - at 63C for 30 m which kills food pathogen
3- non ionizing radiation - such as ultra violet light the organism must have a direct surface

Question 22

Numerate Chemical methods of disinfection ?

Answer 22

1- alcohol- ethyl
2-aldehydes -formaldehydes , gluteraldehydes
3-halogens -chlorine and iodine
4-heavy metals
5-phenolic - cleaning Bench at cncetration 2% - 5%
6- quarternary ammonium compounds- in the laboratory

Question 23

What are the factors influence the activity of the disinfection ?

Answer 23

1- type of organismes present
2- tempreture and ph of process
3-surface nature
4-amount of organics(pus,blood,mucase)
5-length of time incotact
6-type of water avalible
7-number of organsims presesnt 
8-concetration of disinfaction