CARBAPENEM & MONOBACTUM
| A | Vancomycin | |
| B |
Imipenem |
|
| C |
Teicoplanin |
|
| D |
Linezolid |
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. 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.”
All have beta lactam ring EXCEPT –
| A |
Penicillin |
|
| B |
Linezolid |
|
| C |
Cefotaxime |
|
| D |
Imipenem |
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).
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. 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.
| A | beta-lactamase inhibitor | |
| B |
beta-lactam antibiotic |
|
| C |
Antitubercular drug |
|
| D |
Antifungal drug |
Ans. is ‘b’ i.e., beta -lactam antibiotic
Not true about aztreonam ‑
| A |
f3-lactarn |
|
| B |
Monobactarn |
|
| C |
Active against pseudomonas |
|
| D |
Shows cross reactivity with other penicillins |
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.
