Staphylococcus aureus: Morphology,Culture and Biochemical reaction
All of the following statements about staphylococcus aureus are true, EXCEPT:
| A |
Most common source of infection is cross infection from infected people |
|
| B |
About 30% of general population are healthy nasal carriers |
|
| C |
Epidermolysin and TSS toxin are superantigens |
|
| D |
Methicillin Resistance is chromosome mediated. |
All of the following statements about staphylococcus aureus are true, EXCEPT:
| A |
Most common source of infection is cross infection from infected people |
|
| B |
About 30% of general population are healthy nasal carriers |
|
| C |
Epidermolysin and TSS toxin are superantigens |
|
| D |
Methicillin Resistance is chromosome mediated. |
Catalase positive, beta-hemolytic staphylococcus –
| A |
S. aureus |
|
| B |
S. epidermidis |
|
| C |
S. saprophyticus |
|
| D |
None |
Catalase positive, beta-hemolytic staphylococcus –
| A |
S. aureus |
|
| B |
S. epidermidis |
|
| C |
S. saprophyticus |
|
| D |
None |
Ans. is ‘a’ i.e., S. aureus
- All staphylococci are catalase positive.
- Amongst staphylococci, staph. aureus is beta hemolytic.
- Most species of coagulase negative staphylococcus species are non-hemolytic.
Transient colonization is caused by –
| A |
HSV |
|
| B |
Trichomonas vaginalis |
|
| C |
Staphylococcus aureus |
|
| D |
All |
Transient colonization is caused by –
| A |
HSV |
|
| B |
Trichomonas vaginalis |
|
| C |
Staphylococcus aureus |
|
| D |
All |
Ans. is ‘a’ i.e., HSV; ‘b’ i.e., Trichomonas vaginalis; `c’ i.e., Staphylococcus aureus
- Colonization is the multiplication of microorganism on or within the host that does not result in cellular injury.
- However, microorganisms that are colonized on a host may be potential source of infection especially if host susceptibility declines or microorganisms virulence increases.
- Microorganisms residing on human body as normal flora are of two types : ‑
1) Resident flora
– Resident flora are the microorganisms that are always present, usually without altering the client’s health.
2) Transient flora
– Transient flora are episodic organisms, they present for a brief period but do not continually live on/in human body.
Common natural flora at various site of body
|
|
Resident |
Transient flora |
|
Skin |
Corynebacterium, Micrococcus, Coagulase |
Staph aureus, viridans streptococci |
|
|
negative staphylococci, Propionobacterium, Pityrosporrum, Demodex follicularum |
group A streptococci, Enterococcus Malassezia, E.coli, Proteus, Klebsiella, Candida, Trichophyton. |
|
Mouth & |
Str. viridans, Coagulase negative staph., Hemophillus, Peptostreptococci, Bacteriodes, Prevotella, Vellionella, non-meningococcal neisseria, Fusobacterium, Actinomyces |
Group A Streptococcus, Lactobacillus N. meningitidis, Candida, CMV, HSV, Moraxella, Eikenella corrodens. |
|
oropharvnx |
||
|
|
||
|
Nose & |
Coagulase negative staph.. Corynebacterium, |
Non-meningococcal & Meningococcal |
|
Nasopharynx |
Strep. viridans |
neisseria, Staph aureus, Str. pneumoniae, Morexclla |
|
|
||
|
Vagina |
Lactobacillus, Streptococcus, Prevotella, Coagulase negative staphylococci, Gard. vaginalis, Actinomyces |
Candida, Trichomonas vaginalis, Group B streptococci, Enterococcus. |
|
|
||
|
Eve |
Coagulase negative staph, Micrococci, Hemophillus, Corynebacterium |
Bacillus, Strep viridans, Propionobac‑ terium, Staph aureus, str. pneumoniae |
|
Stomach |
|
Streptococci, Lactobacillus, H. Pylori |
|
|
||
|
Small intestine |
Lactobacillus, Streptococcus, Vellionella, Prevotella, Porphyromonas, Bifidobacter Bacteroides, Clostridium, Enterobacteriacease |
Candida, Entamoeba coli, E.Nana, Trichomonas Hominis, Blastocystis hominis |
|
|
||
|
Large intestine |
Bifidobactor, Peptostreptococci, Enterococcus |
Candida, Corynebacterium, Pseudo‑ |
|
|
Lactobacillus, Vellionella, Eubacterium, Fusobacterium, Prevotella, Porphyromonas, Bacteroides, Clostridium, Enterobacteriaceae |
monas, MAC, Entamoeba coli, E.nana, Trichomonas Hominis, Enterovirus, Blastocystis hominis |
|
Urethra |
Corynebacteriurn, Strept viridans, Coagulase negative staph, Lactobacillus |
M. smegmetis, Enterococcus, Mycoplasma, Neoplasma, Bacteroides, Fusobacterium |
Causative organism in acute bacterial endocarditis is –
| A |
Staphylococcus aureus |
|
| B |
Streptococcus viridans |
|
| C |
Pneumococcus |
|
| D |
Streptococcus pyogenes |
Causative organism in acute bacterial endocarditis is –
| A |
Staphylococcus aureus |
|
| B |
Streptococcus viridans |
|
| C |
Pneumococcus |
|
| D |
Streptococcus pyogenes |
Ans. is ‘a’ i.e., Staphylococcus aureus
Streptococcus viridans infects the demaged valve i.e., it causes sabacute endocarditis not acute.
Staphylococcus aureus is a normal inhabitant of:
March 2005
| A |
Throat |
|
| B |
Nose |
|
| C |
Skin |
|
| D |
GIT |
Staphylococcus aureus is a normal inhabitant of:
March 2005
| A |
Throat |
|
| B |
Nose |
|
| C |
Skin |
|
| D |
GIT |
Ans. B: Nose
Staphylococci are Gram-positive spherical bacteria.
S. aureus colonizes mainly the nasal passages(especially anterior pares), but it may be found regularly in most other anatomical locales.
S. epidermidis is an inhabitant of the skin.
For phage typing, how many phages of staphylococcus aureus are used ‑
| A |
12 |
|
| B |
15 |
|
| C |
20 |
|
| D |
23 |
For phage typing, how many phages of staphylococcus aureus are used ‑
| A |
12 |
|
| B |
15 |
|
| C |
20 |
|
| D |
23 |
Ans. is ‘d’ i.e., 23
- Bacteriophage typing of staphylococcus is based on susceptibility of cocci to bacteriphages.
- This is carried out by pattern method where a set of 23 standard typing phages of S. aureus is used to type staphylococcal isolates and distinguish them from one another by their patterns of susceptibility to lysis. o The phage type of a strain is known by designation of the phages that lyse it.
- For example, if a strain is lysed by phages 83A, 84 and 85, it is called type 83A/84/85.
