Beta-lactamases of Moraxella catarrhalis

[Moraxella catarrhalis: virulence and resistance mechanisms]

It is more than a century ago that Moraxella catarrhalis was discovered and described in some detail. However, it was not until the last decade that M. catarrhalis was recognized as a facultative pathogen, namely in otitis media (predominantly in children), sinusitis and nosocomial pneumonia in the group of elderly, debilitated patients. Liberation of endotoxin, histamine, and chemotactically active factors can be considered the major pathogenicity factors. The pathogen can protect itself, on the one hand by binding of the Clq subcomponent of the complement system followed by subsequent formation of a functionally inactive complex with Cl, and on the other hand by inactivation of the terminal (lytic) complement complexes by means of a specific protein on the surface of the outer cell wall. Routine diagnostic procedures require, above all, culture of the pathogen: up to now the detection of specific IgA-antibodies has not been routinely available. More than half of the clinical isolates are known to exhibit beta-lactamase production (BRO-enzymes). This is the reason why combinations of a penicillin compound with a beta-lactamase inhibitor, the group of the newer cephalosporins (including the orally active ones), doxycycline and the macrolides are therapeutically effective.

Comparative evaluation of the clinical and microbiological efficacy of co-amoxiclav vs cefixime or ciprofloxacin in bacterial exacerbation of chronic bronchitis

In an open randomized study 218 outpatients (159 males and 59 females) ranging between 18 and 85 years of age (mean 61.9) suffering from bacterial exacerbation of chronic bronchitis have been randomly treated: 79 with co-amoxiclav (amoxicillin 875 mg+clavulanic acid 125 mg) twice daily, 69 with cefixime (400 mg) once daily, and 70 with ciprofloxacin (500 mg) twice daily for an average period of 10 days. Before treatment start, 234 bacterial strains (105 Gram-positive and 129 Gram-negative) were isolated as the cause of exacerbation; the leading pathogens were Streptococcus pneumoniae and Haemophilus spp. Eradication rates at the end of treatment were 82.2% for the co-amoxiclav group, 77.6% for the cefixime group, and 81.2% for ciprofloxacin group. Clinical success (cure+improvement) was obtained in 90.8% of the cases treated with co-amoxiclav, in 80.9% for the cefixime group and in 85.7% of patients treated with ciprofloxacin. Seven adverse events (8.9%) of which 4 cases of diarrhea and 3 of itching, were recorded in the co-amoxiclav group. Eleven adverse events (14.7%) were recorded in the cefixime group including gastrointestinal disturbances in 6 patients and mild to moderate increase of liver function in 2. Nine adverse events (12.9%) occurred in the ciprofloxacin group, including insomnia in 3 patients, gastrointestinal disturbances in 2, and serious increase of liver function tests in one patient. It can be concluded that there were no statistically significant differences among the three treatment groups. However, co-amoxiclav demonstrated a higher efficacy rate than cefixime and ciprofloxacin and was better tolerated. Therefore, it can be used as a first-choice drug in the treatment of exacerbation of chronic bronchitis.