A Laboratory Assessment of Ciprofloxacin and Comparable Antimicrobial Agents

Abstract

The in vitro activity of ciprofloxacin against a wide range of bacterial isolates was assessed in comparison with norfloxa~in, enoxacin, co-trimoxazole and penicillin (or anapicillin) where appropriate. Minimal inhibitory concentrations (MICs) indicated that ciprofloxacin was highly active against gram-negative bacilli of the Enterobacteriaceae and Pseudomonas groups, notably against strains resistant to gentamicin. Similarly, Staphylococcus aureus (including methiciUin-resistant strains) and Haemophilus influenzae were susceptible, regardless of penicillinase production. Norfloxacin and enoxacin were less active than ciprofloxacin against the majority of species tested, although enoxacin blood levels were generally higher. Most co-trimoxazole-resistant strains were susceptible to the quinoline group of drugs.The quinoline carboxylic acids, derivatives ofnalidixic acid, represent a new development in this class of synthetic antimicrobials. Because of their wider spectrum and enhanced activity, ciprofloxacin, norfloxacin and enoxacin may now be regarded as serious candidates for the treatment of systemic disease, in addition to the role established by their precursors in urinary tract infections. The results of a number of studies (1-5) suggest that the quinolines are possible alternatives to the more conventional beta-lactams and aminoglycosides for the control of significant infections caused by a wide range of bacterial species. Their lack of cross-resistance with the latter antibiotics and high bactericidal activity against gram-negative bacilli, including Pseudomonas spp., should be advantageous in the hospital setting, especially in the immunocompromised patient with granulocytopenia. This report describes a series of comparative determinations of the minimal inhibitory concentration (MIC) of these antimicrobial substances and a few alternatives, using a selection of clinical isolates from hospitals in the Johannesburg region of South Africa. Materials and Methods Antimicrobials and Determination of MICs.A microtitre broth dilution technique was employed for the Enterobacteriaceae, Pseudomonas spp., Staphylococcus aureus and Streptococcus faecalis. Microtitre trays were filled with 0.1 ml samples of antimicrobial dilutions with the use of a Dynatech MIC-2000 dispenser. The antimicrobials had previously been dissolved in Mueller-Hinton broth (Oxoid) at concentrations ranging from 64 to 0.03 rag/1 in a doubling dilution series. Co-trimoxazole was made up in a ratio of 1 : 19 of trimethoprim to sulfamethoxazole, covering a range of 8/152 to 0.004/0.08 mg]l. Trays were prepared and kept at -20 ~ for a maximum of 6 weeks prior to use. A suspension of 5 • 107 colony forming units (CFU) per ml was inoculated into the trays using the Dynatech multipin inoculator, to give a final concentration of approximately 5 X 105 CFU/ml. A supplement of magnesium and calcium cations was used for Pseudomonas aeruginosa. An agar plate dilution method was adopted for Haemophilus spp., Neisseria spp., Streptococcus pneumoniae and S...

Penetration of Ciprofloxacin and Metabolites into Human Lung, Bronchial and Pleural Tissue after 250 and 500 mg Oral Ciprofloxacin

“…This may even [16,22,27]. The good tissue penetration [3,6,7,9,14,15,18,20,23] together with the broad spectrum of antibacterial activity [8,12,25,27], chemical stability [24] and the good safety record [1,19] makes the drug poten tially highly valuable as a primary agent for antibiotic prophylaxis in surgery and for treatment of bronchial and pulmonary infections.…”

Ciprofloxacin concentrations in bone and muscle after oral dosing

“…Ciprofloxacin, the most potent in vitro oxyquinolone derivative, has marked activity against gram-negative bacteria, including Pseudomonas, Serratia, and Enterobacter spp., and staphylococci (1,5,6,11,15). The MICs of ciprofloxacin for 90% of the members of the Enterobacteriaceae, Pseudomonas spp., and Neisseria spp.…”

Pharmacokinetics of ciprofloxacin and effect of repeated dosage on salivary and fecal microflora

“…No new colonization of ciprofloxacin-resistant bacteria for which MICs were above 1.0 mg/liter was observed. C. difficile or its cytotoxin was not detected.Ciprofloxacin, a new antibacterial agent belonging to the series of 4-quinolone carboxylic acids, is chemically related to the less antibacterially active nalidixic acid, norfloxacin, and ofloxacin (6,11,15). Ciprofloxacin is highly active, with MICs mostly below 0.25 mg/liter for gram-negative aerobic rods (e.g., enterobacteria, including Serratia spp.…”

“…and oxidative rods (including Pseudomonas aeruginosa) and below 2 mg/liter for most gram-positive aerobic cocci. The substance is generally less active against anaerobic bacteria (11), and the MIC for Clostridium difficile is between 4 and 8 mg/liter (1).…”