Ciprofloxacin microbial resistance

Answer A- Microbial resistance to fluoroquinolones is increasing, and some strains of Streptococcus pneumoniae are now resistant to ciprofloxacin. The mechanism can involve changes in the structure of topoisomerase IV, one of the targets of fluoroquinolones, which inhibit nucleic acid synthesis. Pneumococcal resistance to penicillins is also increasing via changes in penicillin-binding proteins (PBPs). The other mechanisms listed underlie microbial resistance to other antibiotics as follows sulfonamides (choice B), macrolides (choice C), extended-spectrum penicillins (choice D), and beta-lactams (choice E). 

The first quinolone, nalidixic acid, was isolated as a byproduct of the synthesis of chloroquine. It has been available for the treatment of urinary tract infections for many years. The introduction of fluorinated 4-quinolones, such as ciprofloxacin (Cipro), moxifloxacin (Avelox), and gatifloxacin (Tequin) represents a particularly important therapeutic advance because these agents have broad antimicrobial activity and are effective after oral administration for the treatment of a wide variety of infectious diseases. Relatively few side effects appear to accompany the use of these fluoroquinolones, and microbial resistance to their action does not develop rapidly. Rare and potentially fatal side effects, however, have resulted in the withdrawal from the market of temafloxacin (immune hemolytic anemia), trovafloxacin... 

Published guidelines on the management of catheter-related infections are in favor of the use of ALT for the treatment of catheter-related infections [24]. The in vitro stability of antibiotic-heparin combinations in CVCs was studied by Vercaigne et al. [25]. While ciprofloxacin produced immediate precipitation with heparin, cefazolin, vancomycin and ceftazidime at 10 mg/ml and gentamycin at 5 mg/ml were successfully incubated with heparin (5,000 U/ml) for 72 h in the central venous catheter lumen. Although free antibiotic in CVC solution was reduced, the final concentration was still sufficient for an effective antibiotic-heparin lock [25]. Good evidence is available to support ALT in the prevention of catheter-related bacteremia in patients on hemodialysis [26,27]. However, others have reported that the use of ALT may be limited due to antibiotic toxicity and the appearance of antibiotic-resistant microbial isolates [28, 29]. 

---