In vitro susceptibilities of Bordetella pertussis and Bordetella parapertussis to BAY 12-8039, trovafloxacin, and ciprofloxacin

Pharmacotherapy for Bordetella pertussis infection. I. A synthesis of laboratory sciences

There is considerable history and practice experience both with laboratory susceptibility testing for Bordetella pertussis and clinical treatment. This two-part narrative review provides a synthesis of the laboratory and clinical sciences as they apply to this bacterium and the clinical consequences of treating infection. It is generally held that antibiotic susceptibility testing for B. pertussis is not sufficiently standardised, but there has not been an urgent need to consolidate the same given the lack global experience with major resistance profiles. Experience in China, however, has provided concern for high-level macrolide resistance. The nature of and frequency of such resistance has raised the bar for reconsideration of susceptibility testing given that first-line treatment may be regionally compromised. Disk diffusion and Etest susceptibility testing can be recommended for screening resistance among individual isolates of B. pertussis and on an ad hoc manner. Disk diffusion, Etest and/or critical agar dilution testing can be recommended for large-scale studies. Standards for inoculum, growth atmosphere, timing of interpretation, preferred testing media and controls can be extrapolated from the publications to date. Such methods should be able to detect high-level resistance to several antibiotics, but especially macrolides. Concern for intermediate-susceptible categories requires consideration as well as the correlation with bacteriological and clinical outcomes. Provisional standards can be applied at this time, and modification or fine-tuning of any such standards are open to future investigation.

Emergence of quinolone-resistant Bordetella pertussis in Japan

Six Bordetella pertussis strains isolated from children in Japan from 2004 to 2006 showed high-level resistance to nalidixic acid (NAL; MIC, >256 microg/ml) and decreased susceptibilities to fluoroquinolones. All of the NAL-resistant strains had the same D87G mutation in gyrA.

Moxifloxacin (Avelox): a novel fluoroquinolone with a broad spectrum of activity

Moxifloxacin (Avelox) is a recently-developed fluoroquinolone that has a broad spectrum of antimicrobial activity, including typical respiratory pathogens, atypical and intracellular respiratory pathogens, Gram-negative pathogens and many anaerobes. This spectrum of activity makes moxifloxacin particularly suitable for the therapy of community-acquired respiratory tract infections. It also has enhanced activity against specific bacteria, such as Mycobacteria spp. and Legionella. Moxifloxacin has pharmacologic characteristics that support once-daily dosing regimens and dual routes of excretion that require little or no adjustment for renal or hepatic insufficiency. The drug has maintained an excellent safety profile based upon broad global usage, and no adverse events have occurred that were unanticipated. Streptococcus pneumoniae, which are resistant to earlier fluoroquinolones, are less likely to be resistant to moxifloxacin.

Current pharmacotherapy of pertussis

Human infection with Bordetella pertussis and Bordetella parapertussis causes significant morbidity and mortality. While universal immunisation represents the mainstay of prevention, the purpose of this review is to summarise the current options for antimicrobial chemotherapy of pertussis. Several chemotherapeutic approaches have an important place in therapy and in infection control. Supportive treatment including nasopharyngeal suction, oxygen and parenteral fluids, is essential for infants < 1 year who are at greatest risk of complications and permanent sequelae. Steroids and beta2-agonists are also used in the management of severe neonatal pertussis. Several antibiotics have been shown to reduce the level of bacterial colonisation of the respiratory tract, however, erythromycin is accepted to be the treatment of choice. Erythromycin reduces severity and duration of disease, even if started during the paroxysmal phase. A 14 day course is recommended although side effects may limit compliance; a recent study indicates that a 7 day course may have similar efficacy in terms of eradication and prevention of relapse. Alternatives to erythromycin are clarithromycin, azithromycin and trimethoprim-sulfamethoxazole. Fluoroquinolones have good in vitro activity against both B. pertussis and B. parapertussis and may be useful in the treatment of adult patients with pertussis, although there are no supporting clinical data at present. Erythromycin prophylaxis is also recommended for close household contacts of patients with pertussis.

What's new in the antibiotic pipeline

Many advances have recently been made in the development of chemotherapeutic agents for bacterial infections. As a consequence of problematic antimicrobial-resistant bacteria, research is now directed towards narrow-spectrum agents rather than broad-spectrum agents. Further, orally active agents have always been desirable, but today's cost-saving environment, in line with a desire to minimize treatment costs, values reduced administration costs and keeping patients out of the hospital. There has been a recent increase in research into orally active antibacterial agents, such as carbapenems and cephalosporins, and non-glycopeptide natural products.