Antimicrobial susceptibility of select respiratory tract pathogens in Dakar, Senegal
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Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes, and Streptococcus pneumoniae are the most common causative agents of respiratory tract infections (RTIs). The increase in resistance to current antibacterial agents highlights the need to monitor the resistance pattern of these bacterial pathogens.In this study, we assessed the antibacterial susceptibility of these pathogens causing respiratory tract infections in Dakar, Senegal, during 2007-2008. A total of 290 bacterial isolates (75 H. influenzae, 10 M. catarrhalis, 105 S. pneumoniae, and 100 S. pyogenes) were collected.All H. influenzae isolates were susceptible to amoxicillin/clavulanic acid, ofloxacin, clarithromycin, cephalosporins, and macrolides. Overall, 26.7% of H. influenzae isolates were completely resistant to ampicillin. Among the M. catarrhalis isolates, 30% were resistant to ampicillin. All the isolates of H. influenzae and M. catarrhalis that were resistant to ampicillin were beta-lactamase producing strains. Among the S. pneumoniae isolates, 33.3% isolates exhibited intermediate susceptibility to penicillin G, and one isolate was completely resistant. All five isolates that were resistant to erythromycin expressed the M phenotype. S. pyogenes exhibited high susceptibility to all other antibiotics, except tetracycline. Our study suggests that except for M. catarrhalis, all other bacterial isolates are susceptible to cephalosporins, macrolides, and fluroquinolones.Keywords:
Streptococcus Pyogenes
Amp resistance
Moraxella (Branhamella) catarrhalis
Moraxella (Branhamella) catarrhalis
Beta-lactamase
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The pathogens Streptococcus pyogenes and Moraxella catarrhalis colonize overlapping regions of the human nasopharynx. We have found that M. catarrhalis can dramatically increase S. pyogenes adherence to human epithelial cells and that species-specific coaggregation of these bacteria correlates with this enhanced adherence.
Streptococcus Pyogenes
Moraxella (Branhamella) catarrhalis
Human pathogen
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Moraxella (Branhamella) catarrhalis
Amp resistance
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Objectives To investigate antimicrobial resistance and beta-lactamase production of Moraxella catarrhalis isolates from respiratory tract in children and to understand the characteristics of BRO beta-lactamase gene.Methods From June 2011 to September 2012,401 Moraxella catarrhalis isolates were obtained from respiratory tract in children.Minimum inhibitory concentrations(MIC) of commonly-used antibiotics were determined by microbroth dilution assay,and beta-lactamase production was detected by Nitrocefin disk test.PCR combining restriction endonuclease analysis was employed to do the BRO genotyping.Results 96.5% isolates were beta-lactamase positive(387/401),MIC(MIC50/MIC90) values and resistant rates of beta-lactamase producing isolates were higher than those of non beta-lactamase producing isolates for ampicillin,cefaclor and cefuroxime(P0.05).The positive rate of BRO gene was 99.2% in beta-lactamase producing isolates(384/387),consisting of 93.0% BRO-1 isolates and 7.0% BRO-2 isolates.MIC50 and MIC90 values of BRO-1+isolates were higher than those of BRO-2+isolates for ampicillin,cefaclor,cefuroxime and azithromycin.Conclusions The beta-lactamase production rate is high in Moraxella catarrhalis isolates from respiratory tract in children.BRO1 type was the dominant genotype of beta-lactamase producing isolates,having more influence than BRO-2 type in the influence on some beta-lactams and macrolides.
Cefuroxime
Moraxella (Branhamella) catarrhalis
Amp resistance
Beta-lactamase
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Nasopharyngeal carriage of Moraxella catarrhalis is a risk factor for upper respiratory tract infections and otitis media. In this study, we aimed to characterize BRO beta-lactamases of M. catarrhalis strains isolated from 64 children without any symptoms of respiratory disease. Gram negative diplococci grown on selective media and which are catalase, oxidase, DNase, nitrate reduction positive, glucose, maltose, sucrose and lactose fermentation negative, were diagnosed as M. catarrhalis. Antibiotic susceptibility testing was performed by agar dilution method recommended by NCCLS. BRO beta-lactamases were differentiated by restriction enzyme analysis method. The resistance rate for ampicillin was 18.8% and all the isolates were found to be sensitive to amoxicillin-clavulanate, cefazolin, cefaclor, azithromycin and ciprofloxacin. Out of 64 M. catarrhalis isolates, 57 (89%) were found beta-lactamase positive with nitrocefin disk test (Remel, USA). The presence of BRO beta-lactamases in these 57 strains (89%) was also confirmed by restriction enzyme analysis, while 7 (11%) of them were found to be negative. Among the positive strains, 47 (73.4%) were typed as BRO-1, and 10 (15.6%) were typed as BRO-2. The characterization of BRO beta-lactamases of M. catarrhalis strains in carrier children is important since the high rate of carriage predisposes to respiratory tract infections. As a result, BRO beta-lactamase typing will guide the treatment regimen against the respiratory infections that can occur due to M. catarrhalis in carrier children.
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Respiratory and otitis isolates of 807 Streptococcus pneumoniae, 816 Haemophilus influenzae and 446 Moraxella catarrhalis were collected from 21 clinical microbiology laboratories for antimicrobial susceptibility testing in 1995. After a period of relative stability in 1981 and 1987-1990, beta-lactamase production increased in H. influenzae. Among middle ear isolates from children under 6 years, beta-lactamase production increased from 8% to 24% in H. influenzae and from 81% to 96% in M. catarrhalis since the survey in 1987-1990. 1.2% of S. pneumoniae were penicillin-resistant and 4.2% intermediately resistant; 5 years earlier among otitis isolates of children only 1.7% intermediate resistance was found. Ampicillin resistance was seen among 1.9% of non-beta-lactamase-producing strains of H. influenzae. Resistance to trimethoprim-sulphamethoxazole occurred in 9.4% of S. pneumoniae, 7.4% of H. influenzae and 0.7% of M. catarrhalis. Frequencies of azithromycin resistance were 3.0% in S. pneumoniae and 1.6% in H. influenzae, and those of tetracycline resistance were 6.7% in S. pneumoniae and 1.2% in H. influenzae.
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Objective To distinguish BRO β-lactamase by use of restriction endonuclease analysis and investigate antibacterial agents resistance of Moraxella catarrhalis(M. Catarrhalis) with different BRO β-lactamases .Methods Nasopharyngeal swabs of children with respiratory tract infections from the outpatient department of Beijing Children's Hospital were cultured for isolating M.Catarrhalis. BSAC(british society for antimicrobial chemotherapy) agar diffusion test was used to determine antibacterial agents resistance of M.Catarrhalis.Nitrocefin disk was used to detect β-lactamase. Restriction endonuclease analysis was used to distinguish BRO β-lactamases . Antibacterial agents resistance of M. Catarrhalis with different bro genes was compared.Results (1)95.0% of the 80 strains were beta-lactamase positive. MIC 90 of ampicillin was 32 μg/ml and MIC 90 of cefuroxime,cefaclor and cefotaxime were 4 μg/ml,8μg/ml and 1μg/ml respectively,MIC 90 of tetracycline was 16μg/ml. Among the antibacterial agents,ciprofloxacin was the most sensintive agent.(2)Among 80 strains,6(7.5%) Strains were bro negative,55(68.8%) were bro-1 positive,19(23.8%)were bro-2 positive。Except 2 strains,the results of β-lactamases were same as the results of nitrocefin disk and restriction endonuclease analysis.(3)Compared with bro-2 positive strains,the MIC value of ampicillin and cefaclor for bro-1 positive strains were higher.Conclusions Antibacterial agents resistance of M. Catarrhalis to ampicillin was sierous in China. It should be strengthened to monitor antibacterial agents resistance of M.Catarrhalis. Restriction endonuclease analysis can play an important role on characterizing bro genes,evaluating antibacterial agents resistance of Moraxella Catarrhalis to β-lactam and investigating molecular epideminology
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Abstract This paper presents data relating to Haemophilus influenzae and Moraxella catarrhalis from PROTEKT (1999–2000), a surveillance study that examined the susceptibility of respiratory pathogens to current and new antibacterials. β-Lactamase production is the principal mechanism of resistance to ampicillin and other β-lactam antibacterials in H. influenzae and M. catarrhalis . The PROTEKT study showed that globally, the prevalence of β-lactamase production in H. influenzae varied considerably: of 2948 isolates, 489 (16.6%) were β-lactamase-positive [range: 1.8% (Italy) to 65% (South Korea)]. β-Lactamase-negative, ampicillin-resistant (BLNAR) strains of H. influenzae were uncommon (<0.1%) but their very detection highlights the need for continued vigilance. Overall, few isolates of H. influenzae showed resistance to either macrolides or telithromycin. The emergence of clarithromycin-resistant strains is worrying, however, as such isolates may also show resistance to other macrolides. There was a geographical correlation between β-lactamase production and the prevalence of resistance to chloramphenicol and tetracycline among the H. influenzae isolates. Of 1131 M. catarrhalis isolates, 92% were β-lactamase-positive. Most isolates, however, were fully susceptible to nearly all the antibacterials tested, except ampicillin. The most active were ciprofloxacin and levofloxacin (both having MIC 90 values of 0.03 mg/L), moxifloxacin (MIC 90 0.06 mg/L), azithromycin (MIC 90 ≤ 0.06 mg/L) and telithromycin (MIC 90 0.12 mg/L). Overall, there were no concerns in terms of resistance to fluoroquinolones for both H. influenzae and M. catarrhalis . In summary, the PROTEKT surveillance study confirmed the problem of widespread prevalence of β-lactamase-producing strains of H. influenzae and M. catarrhalis , although these pathogens generally remain susceptible to macrolides, fluoroquinolones and the new ketolide telithromycin.
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Four hundred and thirty-one Streptococcus pneumoniae, 1272 Haemophilus influenzae and 305 Moraxella (Branhamella) catarrhalis were isolated from sputa and identified in 28 UK laboratories during a ten week period in 1990. Disc diffusion susceptibility testing was performed in each centre using identical methods. Species-specific susceptibility breakpoints applied to data for six antimicrobial agents were determined from the distribution of isolates according to zone diameters of inhibition measured in participating laboratories and were correlated with minimum inhibitory concentration data obtained with 302 isolates sent to the coordinating centre. Inter-laboratory reproducibility was estimated by comparing peripheral and coordinating centre results for these 302 isolates and by distributing five reference strains to all laboratories for testing. Reduced susceptibility to ampicillin and amoxycillin-clavulanate was detected in less than 3% of S. pneumoniae, but 8.1% were resistant to tetracycline and 6.5% to erythromycin. Resistance to ampicillin due to production of beta-lactamase occurred in 9.4% of H. influenzae; another 5.2% were resistant to ampicillin and amoxycillin-clavulanate but were beta-lactamase-negative. 4.5% were resistant to tetracycline and most (86.6%) had MICs greater than or equal to 1 mg/L of erythromycin. Zone diameters around ampicillin discs were greater than or equal to 10 mm smaller than those around amoxycillin-clavulanate discs for 241 (79%) of M. catarrhalis. Although only 193/241 had been reported to be beta-lactamase positive by participating laboratories, data obtained at the coordinating centre confirmed that greater than or equal to 10 mm and less than or equal to 3 mm zone size differences correlated with beta-lactamase-positive and -negative isolates respectively. No M. catarrhalis were resistant to amoxycillin-clavulanate and less than 4% were resistant to either tetracycline or erythromycin. The prevalence of resistance to cefaclor was highest among H. influenzae (5.2%) and lowest among S. pneumoniae (0.9%). Only seven of 2008 isolates (two to three per species) were resistant to cefixime. The data suggest that the prevalence of resistance to ampicillin, tetracycline and erythromycin must be taken into consideration when treating respiratory infections.
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The documentation of antimicrobial resistance in respiratory pathogens, contained within the Alexander Project, does not necessarily translate into clinical resistance in the treatment of primary community-acquired pneumonia. There is, in particular, little evidence that penicillin resistance in pneumococci is clinically relevant for the treatment of pneumonia, and there is further evidence that the production of β-lactamase by Haemophilus influenzae may not always be clinically relevant within this setting. β-Lactamase producing H. influenzae and Moraxella catarrhalis should probably be treated with alternative agents when they cause exacerbations of chronic bronchitis. More studies are required to define the clinical breakpoints of macrolide and co-trimoxazole resistance in the treatment of pneumonia.
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