Indications for Prenatal Diagnosis by lnvasive Testing

 Principal Indications for Prenatal Diagnosis by lnvasive Testing

- Advanced maternal age (greater than 35 years)

- Previous child with de novo chromosomal aneuploidy

- Presence of structural chromosome abnormality in one of the parents

- Family history of a genetic disorder that may be diagnosed or ruled out by biochemical or DNA analysis

- Family history of an X-linked disorder for which there is no specific prenatal diagnostic test

- Risk of a neural tube defect (first degree relatives of patients with neural tube defects)

- Fetal abnormalities are suspected on Maternal serum screening and ultrasound examination 

Which of the following is not a sporicidal disinfectant?

 # Which of the following is not a sporicidal disinfectant?

A. Glutaraldehyde

B. Formaldehyde

C. Ethylene oxide

D. Benzalkonium chloride

The correct answer is D. Benzalkonium chloride.

Sporicidal agents are: 

E- Ethylene oxide

F- Formaldehyde

G- Glutaraldehyde

H- Halogens 

Benzalkonium chloride is quartenary ammonium antiseptic which is not sporicidal. Only aldehydes, halogens and ethylene oxide are sporicidal disinfectants. 

Formaldehyde is active against the amino group in the protein molecule. In aqueous solutions, it is marked bactericidal, sporicidal and virucidal. It is used to preserve anatomical specimens and for destroying anthrax spores in hair and wool. 10% formalin containing 0.5% sodium tetraborate is used to sterilize clean metal instruments. 

Glutaraldehyde has an action similar to that of formaldehyde. It is especially effective against the tubercle bacilli, fungi and viruses. 

Ethylene oxide is a colorless liquid with a boiling point of 10.7 degree centigrade and highly penetrating at normal temperature and pressure. Therefore, ethylene oxide can be used for sterilization of heat sensitive equipments like heart lung machine, respirators and dental equipment. 

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Which of the following cannot be reliably used for handwashing?

# Which of the following cannot be reliably used for handwashing?

A. Lysol

B. Cresol

C. Isopropyl alcohol

D. Chlorhexidine

The correct answer is A. Lysol.

Lysol is a phenolic compound derived from coal tar and is highly toxic to humans. It is recommended for disinfection of surfaces in hospital. 

These can be reliably used for handwashing: 

- Chlorhexidine

- Alcohols (isopropyl alcohol, ethyl alcohol)

- Iodine

- Cresol

- Chloroxylenol (dettol)

- Hexachlorophane

- Tincture of iodine

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Pseudomonal infection should not be cleaned by:

 # Pseudomonal infection should not be cleaned by:

A. Dettol

B. Hypochlorite

C. Chlorine

D. Betadine

The correct answer is A. Dettol.

Pseudomonas aeruginosa is heat-labile bacteria, readily killed at 55 degrees celcius in 1 hour. It is also highly susceptible to acid, silver salts, 2% alkaline glutaraldehyde, and disinfectants. 

Due to its sensitivity to silver salts, silver sulphonamide compounds have been used as topical cream in burns. However, Pseudomonas aeruginosa is very strongly resistant to common antiseptics and disinfectants, such as chloroxylenol (dettol), hexachlorophane and quartenary ammonium compounds. Indeed, selective media have been devised for isolation of Pseudomonas aeruginosa incorporating dettol or cetrimide. 

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