Frequency Of Beta-lactamase Production Research Articles

Beta-lactamase production by oral anaerobic gram-negative species in infants in relation to previous antimicrobial therapy.

The frequency of beta-lactamase production in gram-negative bacteria has increased considerably during recent years. In this study, beta-lactamase production by oral anaerobic gram-negative rods isolated from saliva was longitudinally examined for 44 Caucasian infants at the ages of 2, 6, and 12 months in relation to their documented exposure to antibiotics. Isolates showing decreased susceptibility to penicillin G (1 microg/ml) were examined for beta-lactamase production by using a chromogenic cephalosporin disk test. beta-Lactamase-positive, gram-negative anaerobic species were found in 11, 55, and 89% of each age group, respectively. beta-Lactamase production was most frequent among organisms of the Prevotella melaninogenica group. At 12 months, 73% of the infants harbored beta-lactamase-producing members of the P. melaninogenica group, 55% had nonpigmented Prevotella species, 25% had Porphyromonas catoniae, 23% had Fusobacterium nucleatum, and 5% had Capnocytophaga species. Several beta-lactamase-producing species could be simultaneously found in the infants' mouths. The presence of beta-lactamase-producing species was significantly associated with the infants' exposure to antibiotics through antimicrobial treatments given to the infants and/or their mothers.

Beta-lactamase production by oral pigmented Prevotella species isolated from young children.

The frequency of beta-lactamase production by oral pigmented Prevotella species isolated from 23 healthy young children and the minimal inhibitory concentrations (MICs) for 186 available beta-lactamase-positive isolates were examined by using the chromogenic cephalosporin disk test (AB BIODISK, Solna, Sweden) and the Etest (AB BIODISK) and/or the agar dilution method of the National Committee for Clinical Laboratory Standards (Villanova, PA, USA), respectively. beta-Lactamase-positive Prevotella melaninogenica strains were isolated from all children, and more than two-thirds of the Prevotella denticola and Prevotella loescheii strains isolated from the children were beta-lactamase-positive. The beta-lactamase-producing Prevotella intermedia group consisted of Prevotella nigrescens and the P. intermedia/ P. nigrescens-like organism (PINLO); P. intermedia was not found. Only two P. nigrescens isolates but most of the PINLO isolates produced beta-lactamase. The MICs for beta-lactamase-producing strains varied between 0.38 and 64 micrograms/mL. beta-Lactamase production by oral pigmented Prevotella species colonizing young children is already frequent. The phenomenon should be taken into account in the treatment of pediatric anaerobic infections of oral origin.

Production of betalactamase by respiratory tract bacteria in children: relationship to antibiotic use.

Sales of antibiotics have increased in Sweden during the past decade. This has been paralleled by an increase in the frequency of beta-lactamase-producing respiratory tract bacteria. To investigate the effects of regional differences in use of antibiotics on beta-lactamase production in respiratory tract bacteria, we collected nasopharyngeal specimens and information about antibiotic use from 1133 children attending day-care centres in four rural municipalities with low use, and one urban municipality with high use of antibiotics, use being assessed from pharmacy sales. The frequency of beta-lactamase production among isolates of Branhamella catarrhalis and Moraxella nonliquefaciens was significantly higher in the urban municipality. This appeared to be a long-term ecological effect of differences in the level of use of antibiotics between the urban and rural populations, rather than an effect of recent antibiotic treatment of individual patients.

Upper respiratory tract infections. Ecological and therapeutic aspects of beta-lactamase production with special reference to Branhamella catarrhalis.

Available data indicate that the most common beta-lactamase produced by Branhamella catarrhalis is plasmid mediated. The same enzyme occurs in Moraxella nonliquefaciens, a commensal in the upper respiratory tract. The ability to produce the enzyme, which is known as BRO-1, can be transferred by conjugation from M. nonliquefaciens to B. catarrhalis. Since the first beta-lactamase-producing strains of B. catarrhalis appeared in 1977, the frequency of beta-lactamase production has increased rapidly; figures as high as 76% have been reported. The plasmid-mediated beta-lactamase TEM-1 occurs in several species of the genus Haemophilus. While the frequency of beta-lactamase production in H. influenzae is reported to be 10-15%, the incidence is significantly higher in non-pathogenic Haemophilus species. Both phenoxymethyl-penicillin and ampicillin promote the occurrence of beta-lactamase-producing strains, but the selective pressure exerted by ampicillin seems to be more pronounced. It may be possible to reduce the ecological effects of the penicillins by avoiding overdiagnosis of the most common bacterial infections of the respiratory tract, and by shortening the courses of antibiotic treatment.

Antibiotic resistance in staphylococci from a hospital environment.

The antibiotic resistance of Staphylococcus aureus and coagulase-negative staphylococci has been followed over 4 years (1977-1980). 90% of the strains produced beta-lactamase. Coagulase-negative staphylococci were more resistant than S. aureus, although beta-lactamase production occurred more rarely. Strains from the sputum of children with cystic fibrosis (CF) were more multiresistant than isolates from other sources. The strains from hospitalized patients (HP) were more resistant than isolates from out-patients. A higher frequency of beta-lactamase production occurred among strains from CF and HP patients compared to out-patients. This occurred in samples from pus and wounds in 66% of the strains derived from non-hospitalized patients compared with 93% from surgical patients.

Activity of erythromycin against Haemophilus influenzae from respiratory tract infections.

Ampicillin and amoxycillin are very frequently used for treating respiratory infections due to Haemophilis influenzae, but the emergence of beta-lactamase producing strains of this organism may limit their use. Erythromycin would be a suitable alternative but to date variable absorptions and reported minimal inhibitory concentrations (MICs) outside the range of achievable blood levels of erythromycin have prevented its use. The purpose of this study was to determine the MICs of erythromycin for strains of H. influenzae isolated from patients with lower respiratory tract infection and the frequency of beta-lactamase production in these strains. Eighty-five of 100 strains were sensitive to erythromycin (MIC much less than 2.00 mg/L). Eleven strains were resistant to ampicillin and 10 of these produced beta-lactamase. Nine beta-lactamase producing strains had MICs to erythromycin of 2.0 mg/L or less. With the blood levels of erythromycin obtainable with new formulations, this antibiotic should prove of use in the treatment of respiratory infections due to H. influenzae.