Ofloxacin

Synthesis of Mn-ofloxacin complex, experimental and in silico DNA binding evaluation, biological activity assessment

Metal-fluoroquinolones have more antibacterial and cytotoxic effects compared to free fluoroquinolones. In this work, a bidentated Mn (II) complex with ofloxacin (MOC) was synthesized and its cytotoxicity activity, oxidative stress and DNA binding were studied. Anti- proliferative and cytotoxic tests revealed that MOC exhibits better anti proliferative and cytotoxic activities compared to OFL which was attributed to the more interaction of MOC with DNA. Therefore, the interaction of MOC with DNA was investigated by using voltammetry, UV-Vis, fluorescence, and in silico methods. The results revealed that MOC interacts with DNA via electrostatic and outside hydrogen binding via minor groove. The proposed DNA binding modes may support the greater in-vitro cytotoxicity of MOC compared to OFL alone.

Effects of ofloxacin on the structure and function of freshwater microbial communities

Ofloxacin (OFL) is a broad-spectrum fluoroquinolone antibiotic frequently used in clinic for treating bacterial infections. The discharged OFL would inevitably enter into aquatic ecosystems, affecting the growth of non-target microorganisms, which may result in micro-ecosystem imbalance. To the best of our knowledge, researches in this area are rather sparse. The present study evaluated the response of photosynthetic microorganisms (cyanobacteria, eukaryotic algae) and aquatic microbial community to OFL in a microcosm. Results showed that ofloxacin presented an inhibitory effect on the growth Microcystis aeruginosa. Although 0.1 mg/L OFL has no significant impact on alpha diversity of the microbial communities, it obviously altered the structure and decreased the species interaction of prokaryotic community by reducing the capacities of nitrogen fixation, photosynthetic and metabolic capacity of the microbial community. This study pointed out that the residual OFL in water would disturb the balance of the aquatic micro-ecology, suggesting that more attentions should be given to the negative effects of antibiotics and other bioactive pollutants on aquatic environments.

Crystal Structure of the Fab Fragment of an Anti-ofloxacin Antibody and Exploration of Its Specific Binding

The limited knowledge on the mechanism of interactions between small contaminants and the corresponding antibodies greatly inhibits the development of enzyme-linked immunosorbent assay methods. In this study, the crystal structure of a Fab fragment specific for ofloxacin was obtained. On the basis of the crystal characteristics, the modeling of the interactions between ofloxacin and the Fab revealed that TYR31 and HIS99 of the heavy chain and MET20 and GLN79 of the light chain formed a hydrophobic region and that SER52 and ALA97 of the heavy chain and TYR35 of the light chain formed a salt bridge and two hydrogen bonds for specific binding. The key roles of SER52 and ALA97 were further confirmed by site-directed mutation. A specificity analysis using 14 ofloxacin analogues indicates that the length of the bond formed between the piperazine ring and the antibody plays key roles in specific recognition. This work helps to clarify the mechanisms through which antibodies recognize small molecules and improve immune detection methods.

Newer concepts in antimicrobial therapy

Antimicrobial agents continue to play a significant role in clinical practice not only due to their active role in the treatment of bacterially induced infections. The accompanying anti-inflammatory characteristics and their antagonism against superantigens add to their importance. The practitioner must also be aware of both overt and covert unwanted effects. During the past decade, the new quinolones, advanced macrolides, and better cephalosporins have been introduced. The staid penicillins have been up-graded with the addition of a beta-lactamase inhibitor. Many antibiotics have been available for several decades but new uses for them and their derivatives permit the dermatologist to have a more versatile armamentarium. Rifamycin has been shown to be effective in the treatment of leishmaniasis. The new macrolide, clarithromycin, will reduce the lesions of acne vulgaris and acne rosacea. Although phototoxicity was well recognised in the sulfonomides, several quinolones can create similar light-induced problems. Bullous diseases are known to be instigated by the penicillins, while vasculitis may be caused by a quinolone. Even porphyria has been reported to be induced by a tetracycline. Antimicrobial therapy has been an integral part of dermatologic practice since the introduction of the sulfa drugs six decades ago. Whether skin is affronted by more pathogenic bacteria than any other organ or whether the percentage of infectious etiologies is greater for cutaneous maladies than for other organ afflictions is not germane to this presentation. The facts remain that signs and symptoms of many dermatitides are diminished or even eliminated by antimicrobials [1, 2, 3, 4].

North American (United States and Canada) comparative susceptibility of two fluoroquinolones: ofloxacin and ciprofloxacin. A 53-medical-center sample of spectra of activity. North American Ofloxacin Study Group

Ofloxacin, a newer broad-spectrum fluoroquinolone, was evaluated against > 12,000 clinical isolates in a multicenter surveillance trial in the United States and Canada using the standardized disk diffusion method. A total of 53 geographically diverse clinical microbiology laboratories contributed zone diameter results for ofloxacin, ciprofloxacin, and norfloxacin for urinary tract infection (UTI) isolates; and ofloxacin and ciprofloxacin for respiratory tract infection (RTI) isolates, skin and soft tissue infection (SSTI) isolates, and genital tract pathogen isolates. In both the USA and Canada, ofloxacin was shown to have the wide spectrum of activity as follows: RTI isolates, ofloxacin (92.2%-93.8% susceptible) > ciprofloxacin (89.5%-90.4%); SSTI isolates, ofloxacin (87.1%-93.6%) > ciprofloxacin (78.8%-90.4%); UTI isolates, ofloxacin (91.6%-92.5%) > norfloxacin (87.3%-91.7%) > ciprofloxacin (86.4%-89.7%); and genital tract isolates, ofloxacin (94.0%) > ciprofloxacin (85.4%) (Canada only). US strains resistant to ofloxacin were confirmed by reference laboratory tests. Confirmed ofloxacin resistance, other than among staphylococci or nonenteric bacilli, was rare. The species most often found to be resistant to both ofloxacin and ciprofloxacin were methicillin-resistant staphylococci, Acinetobacter spp., and Enterococcus spp. From these contributing US and Canadian laboratory studies, ofloxacin appears to have a balanced spectrum of potential clinical use (91.8% susceptible aerobic isolates), particularly against Gram-positive pathogens and some species resistant to ciprofloxacin. The combined overall isolate (12,241 isolates) rates of susceptibility for ciprofloxacin (four infection sites) and norfloxacin (UTI only) were 87.3% and 88.8%, respectively. Monitoring for increasing fluoroquinolone resistance should be considered, however, as greater use of drugs in this class develops.

The North American component (the United States and Canada) of an International Comparative MIC trial monitoring ofloxacin resistance

Common lots of reference MIC (minimum inhibitory concentration) method reagents were used to monitor ofloxacin, a newer fluoroquinolone, and 13 other drugs against 3200 recent clinical isolates in February-April 1992. Five medical centers in the United States and Canada contributed 640 strains per facility as follows: Escherichia coli, Staphylococcus aureus, coagulase-negative staphylococci, Klebsiella spp., and Pseudomonas aeruginosa (100 strains each); Streptococcus pneumoniae (40 strains); and Enterobacter cloacae, Serratia marcescens, Salmonella spp., Haemophilus influenzae, and Moraxella catarrhalis (20 strains each). Quality-control strains were processed concurrently, MICs recorded, and data processed at a common location. Selected ofloxacin-resistant isolates were retested at a reference laboratory to confirm resistances and determine cross-resistant patterns. Results indicate the following (a) fluoroquinolones were superior in usable spectrum of activity to other orally administered drugs (for example, cefaclor, cefixime, ampicillin, amoxicillin-clavulanate, minocycline, oxacillin, and trimethoprim-sulfamethoxazole); (b) ofloxacin and ciprofloxacin were generally equal to gentamicin and cefotaxime against commonly isolated Gram-negative pathogens; (c) fluoroquinolone resistance was rare among enteric bacilli, pneumococci (ciprofloxacin > ofloxacin), H. influenzae, and M. catarrhalis, but more common among oxacillin-resistant staphylococci and P. aeruginosa; (d) cross resistance was generally observed between ofloxacin and ciprofloxacin but was species or genus dependent; and (e) a new fluoroquinolone, levofloxacin, demonstrated promising activity against contemporary pathogens.

Quinolones in the treatment of lower respiratory tract infections in adult patients

The potential role of quinolones is discussed on the basis of data obtained during the past 2 years from epidemiological studies, in vitro investigations, animal experiments and clinical trials. Although the newest compounds exhibit good activity against Streptococcus pneumoniae and intracellular pathogens in animal models, the role of quinolones as first line therapy in community-acquired pneumonia is still debatable and may be modified according to clinical presentation and the rate of resistance of pneumococci to beta-lactams and macrolides. Cost-utility and cost-benefit studies are required to delineate precisely the role of quinolones in the treatment of acute exacerbations of chronic bronchitis. In addition, promising results indicating a possible future for the clinical use of quinolones in the therapy of mycobacterial infections have been obtained.