Carbapenem & Monobactum

CARBAPENEM & MONOBACTUM

Q. 1

A diabetic patient developed cellulitis due to S. aureus, which was found to be methicillin resistant on the antibiotic sensitivity testing. All of the following antibiotics will be appropriate except ‑

 A

Vancomycin

 B

Imipenem

 C

Teicoplanin

 D

Linezolid

Q. 1

A diabetic patient developed cellulitis due to S. aureus, which was found to be methicillin resistant on the antibiotic sensitivity testing. All of the following antibiotics will be appropriate except ‑

 A

Vancomycin

 B

Imipenem

 C

Teicoplanin

 D

Linezolid

Ans. B

Explanation:

Ans. is ‘b’ i.e., Imipenem

Methicillin – resistant staphylococcus – aureus (MRSA)

.  Most staphylococci are penicillin resistant because they secrete penicillinase.

.   To overcome this resistance, penicillinase resistant penicillins, e.g. methicillin and nafcillin were developed.

.   MRSA is a strain of staphylococcus aureus that has acquired multi-drug resistance – even against methicillin and nafcillin (penicillinase resistant penicillin).

Treatment of S. aureus infections

.                         Sensitive to penicillin                  —> Penicillin G is the DOC.

.                         Pt. with penicillin allergy            —> Cefazoline is the DOC.

MRSA     —> Vancomycin is the DOC.

Methicillin – resistant staphylococcus – aureus (MRSA)

.                         Most staphylococci are penicillin resistant because they secrete penicillinase.

.                         To overcome this resistance, penicillinase resistant penicillins, e.g. methicillin and nafcillin were developed.

.                       MRSA is a strain of staphylococcus aureus that has acquired multi-drug resistance – even against methicillin and nafcillin (penicillinase resistant penicillin).

Treatment of S. aureus infections

.                         Sensitive to penicillin                  —> Penicillin G is the DOC.

.                         Pt. with penicillin allergy            —> Cefazoline is the DOC.

.                         MRSA                                            —> Vancomycin is the DOC.

.                         Other drugs for MRSA are

–                                                                                TMP – SMX                               – Levofloxacin                     – Linezolid                             –Tigecyclin

–                                                                                Minocyclin                                – Quinopristin                       – Daptomycin                       – Teicoplanin (KDT – 691)

– Ciprofloxacin                              – Dalfopristin                        – Oritavancin

.                         Adjunctive drugs (those that should be used only in combination with other antimicrobial agents) for M.R.S.A. are gentamycin, rifampin, fusidic acid.

“The carbapenem imipenem has excellent activity against methicillin – senstive S. aureus but not M.R.S.A.”


Q. 2

All have beta lactam ring EXCEPT –

 A

Penicillin

 B

Linezolid

 C

Cefotaxime

 D

Imipenem

Q. 2

All have beta lactam ring EXCEPT –

 A

Penicillin

 B

Linezolid

 C

Cefotaxime

 D

Imipenem

Ans. B

Explanation:

Ans. is ‘b’ i.e., Linezolid

beta-lactam antibiotics contain beta-lactam ring. These are penicillins, cephalosporins (e.g. cefotoxime), monobactams (aztreonam) and carbapenems (imipenem, meropenem).


Q. 3

True about imipenem is –

 A

It is a narrow spectrum antibiotic

 B

It is easily broken by beta lactam

 C

It can be used with cilastatin

 D

It is used with sulbactam

Q. 3

True about imipenem is –

 A

It is a narrow spectrum antibiotic

 B

It is easily broken by beta lactam

 C

It can be used with cilastatin

 D

It is used with sulbactam

Ans. C

Explanation:

Ans. is ‘c’ i.e., It can be used with cilastatin

o A limiting feature of imipenem is its rapid hydrolysis by the enzyme dehydropeptidase-I located on the brush border of renal tubular cells. Cilastatin is a reversible inhibitor of dehydropeptidase -1. It protects the imipenem from this enzyme.

o Carbapenems have the widest spectrum of all currently available antimicrobials, being bactericidal against most gram positive andgram negative aerobic and anaerobic pathogenic bacteria.

Quiz In Between


Q. 4

Aztreonam is a/an –

 A

beta-lactamase inhibitor

 B

beta-lactam antibiotic

 C

Antitubercular drug

 D

Antifungal drug

Q. 4

Aztreonam is a/an –

 A

beta-lactamase inhibitor

 B

beta-lactam antibiotic

 C

Antitubercular drug

 D

Antifungal drug

Ans. B

Explanation:

Ans. is ‘b’ i.e., beta -lactam antibiotic


Q. 5

Not true about aztreonam ‑

 A

f3-lactarn

 B

Monobactarn

 C

Active against pseudomonas

 D

Shows cross reactivity with other penicillins

Q. 5

Not true about aztreonam ‑

 A

f3-lactarn

 B

Monobactarn

 C

Active against pseudomonas

 D

Shows cross reactivity with other penicillins

Ans. D

Explanation:

Ans. is ‘d’ i.e., Shows cross reactivity with other penicillins

Aztreonam

  • It belongs to monobactams group of 13-lactam antibiotics.
  • It is active against gram negative organisms including pseudomonas, but has no activity against gram positive organisms or anaerobes fi-lactam antibiotic with aminoglycosides spectrum.
  • It is the only fi-lactam antibiotic that lack cross-reactivity with other P-lactam antibiotics, permiting its used in patients allergic to penicillins or cephalosporins.

Quiz In Between



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