Review of cefditoren, an advanced-generation, broad-spectrum oral cephalosporin

Discovery and Development of Antibacterial Agents: Fortuitous and Designed

Today, antibacterial drug resistance has turned into a significant public health issue. Repeated intake, suboptimal and/or unnecessary use of antibiotics, and, additionally, the transfer of resistance genes are the critical elements that make microorganisms resistant to conventional antibiotics. A substantial number of antibacterials that were successfully utilized earlier for prophylaxis and therapeutic purposes have been rendered inadequate due to this phenomenon. Therefore, the exploration of new molecules has become a continuous endeavour. Many such molecules are at various stages of investigation. A surprisingly high number of new molecules are currently in the stage of phase 3 clinical trials. A few new agents have been commercialized in the last decade. These include solithromycin, plazomicin, lefamulin, omadacycline, eravacycline, delafloxacin, zabofloxacin, finafloxacin, nemonoxacin, gepotidacin, zoliflodacin, cefiderocol, BAL30072, avycaz, zerbaxa, vabomere, relebactam, tedizolid, cadazolid, sutezolid, triclosan and afabiacin. This article aims to review the investigational and recently approved antibacterials with a focus on their structure, mechanisms of action/resistance, and spectrum of activity. Delving deep, their success or otherwise in various phases of clinical trials is also discussed while attributing the same to various causal factors.

Potent, specific MEPicides for treatment of zoonotic staphylococci

Coagulase-positive staphylococci, which frequently colonize the mucosal surfaces of animals, also cause a spectrum of opportunistic infections including skin and soft tissue infections, urinary tract infections, pneumonia, and bacteremia. However, recent advances in bacterial identification have revealed that these common veterinary pathogens are in fact zoonoses that cause serious infections in human patients. The global spread of multidrug-resistant zoonotic staphylococci, in particular the emergence of methicillin-resistant organisms, is now a serious threat to both animal and human welfare. Accordingly, new therapeutic targets that can be exploited to combat staphylococcal infections are urgently needed. Enzymes of the methylerythritol phosphate pathway (MEP) of isoprenoid biosynthesis represent potential targets for treating zoonotic staphylococci. Here we demonstrate that fosmidomycin (FSM) inhibits the first step of the isoprenoid biosynthetic pathway catalyzed by deoxyxylulose phosphate reductoisomerase (DXR) in staphylococci. In addition, we have both enzymatically and structurally determined the mechanism by which FSM elicits its effect. Using a forward genetic screen, the glycerol-3-phosphate transporter GlpT that facilitates FSM uptake was identified in two zoonotic staphylococci, Staphylococcus schleiferi and Staphylococcus pseudintermedius. A series of lipophilic ester prodrugs (termed MEPicides) structurally related to FSM were synthesized, and data indicate that the presence of the prodrug moiety not only substantially increased potency of the inhibitors against staphylococci but also bypassed the need for GlpT-mediated cellular transport. Collectively, our data indicate that the prodrug MEPicides selectively and robustly inhibit DXR in zoonotic staphylococci, and further, that DXR represents a promising, druggable target for future development.

Liver uptake of cefditoren is mediated by OATP1B1 and OATP2B1 in humans and Oatp1a1, Oatp1a4, and Oatp1b2 in rats

OATPs and Oatps mediated liver uptake of cefditoren in humans and in rats.

Efficacy of cefditoren pivoxil and amoxicillin/clavulanate in the treatment of pediatric patients with acute bacterial rhinosinusitis in Thailand: a randomized, investigator-blinded, controlled trial

BACKGROUND

The recommended treatment for acute bacterial rhinosinusitis in adults and children is 10 to 14 days of high doses of oral cephalosporins or amoxicillin/clavulanate.

OBJECTIVE

This study compared the clinical efficacy and tolerability of cefditoren pivoxil and amoxicillin/clavulanate in children with uncomplicated acute bacterial rhinosinusitis.

METHODS

This was a randomized, investigator-blinded, controlled study in pediatric patients (age 1-15 years) with clinical and radiographic signs and symptoms of acute rhinosinusitis. Patients were allocated to receive either cefditoren (8-12 mg/kg daily) or amoxicillin/clavulanate (80-90 mg/kg amoxicillin daily) for 14 days. Changes in sinus symptoms were assessed daily by patients or their parents using a quantitative symptom score (the S5 score). Rates of improvement, the primary efficacy measure, were also evaluated by the study investigators 7 and 14 days after the initial visit. Secondary outcome measures included time to improvement, adverse effects, and rates of relapse (assessed at days 21 and 28) and recurrence (assessed at day 60) of sinus symptoms. Relapse was defined as a subjective rating of lack of improvement at day 21 or 28 in a patient rated as improved on day 14, and recurrence was defined as sinus symptoms lasting for >or=10 days during the second month of follow-up in a patient rated as improved on day 28. Time to improvement was defined as the number of days between the initial visit and the time at which caregivers noted an improvement in patients' symptoms. Adverse events were monitored by parents/caregivers using a self-administered questionnaire and were also elicited by telephone contact.

RESULTS

The study enrolled 142 pediatric patients: 70 in the cefditoren group (42 males, 28 females; median age, 7.15 years) and 72 in the amoxicillin/clavulanate group (37 males, 35 females; median age, 6.60 years). Four patients in the cefditoren group were excluded from the study analyses (2 who were noncompliant [used <80% of the assigned medication] and 2 who developed infection at other sites). There were no significant differences in baseline medical history or signs and symptoms between the 2 groups. Rates of improvement at day 14 in the cefditoren and amoxicillin/clavulanate groups were 78.8% (52/66) and 84.7% (61/72), respectively (P = NS). There was no significant difference in the change in S5 scores between groups at day 14. The median time to improvement was 3.0 days in both groups. There were no significant differences between groups in rates of relapse (9.1% and 11.1%) or recurrence (3.0% and 5.6%) of sinus symptoms. The most common adverse event in both groups was diarrhea, occurring in 4.5% of the cefditoren group and 18.1 % of the amoxicillin/clavulanate group (P = 0.02).

CONCLUSION

In these children with acute bacterial rhinosinusitis, there were no significant differences between cefditoren and amoxicillin/clavulanate, the currently recommended treatment, in terms of rates of response, relapse, or recurrence.

Cefditoren pivoxil: a review of its use in the treatment of bacterial infections

Cefditoren pivoxil (Spectracef, Meiact) is a third-generation oral cephalosporin with a broad spectrum of activity against pathogens, including both Gram-positive and -negative bacteria, and is stable to hydrolysis by many common beta-lactamases. Cefditoren pivoxil is approved for use in the treatment of acute exacerbations of chronic bronchitis (AECB), mild-to-moderate community-acquired pneumonia (CAP), acute maxillary sinusitis, acute pharyngitis/tonsillitis and uncomplicated skin and skin structure infections (indications may differ between countries). In clinical trials in adults and adolescents, cefditoren pivoxil demonstrated good clinical and bacteriological efficacy in AECB, CAP, acute maxillary sinusitis, acute pharyngitis/tonsillitis and uncomplicated skin and skin structure infections and was generally well tolerated. Thus, cefditoren pivoxil is a good option for the treatment of adult and adolescent patients with specific respiratory tract or skin infections, particularly if there is concern about Streptococcus pneumoniae with decreased susceptibility to penicillin, or beta-lactamase-mediated resistance among the common community-acquired pathogens.

Antimicrobial susceptibility of Haemophilus influenzae, Haemophilus parainfluenzae and Moraxella catarrhalis isolated from adult patients with respiratory tract infections in four southern European countries. The ARISE project

Over a 7-month period in 2000-2001, 1213 Haemophilus influenzae, 112 Haemophilus parainfluenzae and 142 Moraxella catarrhalis isolates were recovered from adult patients with respiratory tract infections. Patients were from four southern European countries (Spain, Italy, Portugal and Greece). The antimicrobial susceptibility of the isolates to 11 antibiotics was determined in a central laboratory. The most active drugs on the basis of MICs were levofloxacin, cefditoren, cefotaxime, cefpodoxime and amoxicillin/clavulanate. MICs > or = 2 mg/l for amoxicillin were found in 19.5, 28.6, and 75.4% of H. influenzae, H. parainfluenzae and M. catarrhalis isolates, respectively. Isolates of H. influenzae and H. parainfluenzae with reduced susceptibility or that were fully resistant to amoxicillin/clavulanate, cefuroxime and clarithromycin were detected (0.2-1.8%) as well as M. catarrhalis resistant to clarithromycin (0.7%). Regular surveys of resistance patterns for antimicrobial agents are necessary.

Antimicrobial resistance among clinical isolates of Streptococcus pneumoniae isolated in four southern European countries (ARISE project) from adult patients: results from the cefditoren surveillance program

From four southern European countries (Spain, Italy, Portugal, and Greece) 877 Streptococcus pneumoniae isolates were recovered from adult patients with respiratory tract infections between September 2000 and March 2001. The antimicrobial susceptibility to 11 antibiotics was determined in a central laboratory. Penicillin resistance was high in Greece (47.1%) and Spain (25.1%) but much lower in Portugal (7.9%) and Italy (4.8%). On the other hand, erythromycin resistance was high in Italy (38.5%) and Spain (36.2%) with no statistical difference with Greece (29.4%) but reaching significance (p <0.01) with Portugal (15.7%). Resistance to levofloxacin was low (1.5%) but present in Spanish and Italian isolates. Cefditoren, a new cephem antibiotic tested, was the most potent compound (MIC90 = 0.5 microg/ml) followed by levofloxacin and cefotaxime (MIC90 = 1 microg/ml). Given the high rates of penicillin and macrolide resistance reported, there is an evident need for new drugs and continued antimicrobial surveillance of S. pneumoniae.