Antibiotic susceptibilities of Haemophilus influenzae in central Scotland

ObjectiveTo ascertain the incidence of antibiotic resistance in Haemophilus influenzae in central Scotland and the β-lactamases produced by these isolates.MethodsA total of 213 H. influenzae isolates from four medical lefts in Scotland [Aberdeen (n = 58), Edinburgh (n = 55), Glasgow (n = 64) and Dundee (n = 36)] were tested for susceptibility to a range of antimicrobials including β-lactams, β-lactam/β-lactamase-inhibitor combinations, and a representative 4-quinolone, antifolate and macrolide. Susceptibility testing of the β-lactam/β-lactamase-inhibitor combination amoxicillin plus clavulanic acid was conducted at both 2:1 and 4:1 ratios and with clavulanic acid fixed at a concentration of 2 mg/L. Each strain was further investigated for the presence of β-lactamase activity.ResultsAlthough the incidence of resistance to amoxicillin was 15%, in the presence of clavulanic acid, this resistance was reduced to 4.2%, 5.6% and 4.2% with the 2:1 ratio, 4:1 ratio and 2 mg/L fixed concentration, respectively. Sixteen percent of the isolates demonstrated immediate β-lactamase production. Isoelectric focusing showed that 77.4%, 16.1% and 6.5% of the β-lactamase-positive strains were found to contain TEM-1, VAT-1 and both TEM-1 and VAT-1 β-lactamases, respectively. A further 29% of the strains were recognized as being β-lactamase-positive after prolonged incubation with nitrocephin.ConclusionsThis study suggests that current testing for β-lactamases may underestimate the prevalence of β-lactamase production in H. influenzae

Comparative in vitro activity of telithromycin against macrolide-resistant and -susceptible Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae

Objectives: The first objective was to investigate the in vitro activity of telithromycin against respiratory tract pathogens in comparison with other antimicrobial agents. The second objective was to identify the influence of the erm(B) and mef(A) genes on the susceptibility of Streptococcus pneumoniae to telithromycin. Methods: The in vitro activity of telithromycin against S. pneumoniae, Moraxella catarrhalis and Haemophilus influenzae, isolated from the UK and 40 macrolide-resistant S. pneumoniae from four different countries was compared with a variety of antimicrobial agents. The 140 isolates were examined for the presence of the erm(B) and mef(A) genes. The impact of 5% CO2 on susceptibility testing was also investigated. Results: Telithromycin showed greatest activity against S. pneumoniae, but also had good activity against M. catarrhalis and H. influenzae, which was independent of their resistance profiles to other antibiotics. The MIC90 of telithromycin for S. pneumoniae was 0.12 mg/L, which was 64-fold lower than the lowest macrolide MIC; 21% of the S. pneumoniae were macrolide resistant. Thirty-eight per cent of the macrolide-resistant strains were erm(B)-positive and 62% were mef(A)-positive, but no strain contained both genes. The activity of telithromycin was similar to that of azithromycin against both M. catarrhalis and H. influenzae, Erythromycin was slightly less active: 1% and 8% of M. catarrhalis and H. influenzae, respectively, were resistant to erythromycin, but none were resistant to telithromycin. Five per cent of the S. pneumoniae strains and 4% of the H. influenzae strains changed from telithromycin susceptible to non-susceptible entirely because of the incubation conditions. The MIC50s and MIC90s of S. pneumoniae, M. catarrhalis and H. influenzae increased by one dilution when incubated in CO2. Conclusions: Telithromycin has shown high in vitro activity against S. pneumoniae, including those strains that are macrolide susceptible and resistant as well as M. catarrhalis and H. influenzae. This study has also demonstrated that there is no cross-resistance between erythromycin and telithromycin. The impact of 5% CO2 on susceptibility testing should be investigated further before providing definite guidelines on telithromycin susceptibility testing

Microbiology and drug resistance mechanisms of fully resistant pathogens

The acquisition of vancomycin resistance by Gram-positive bacteria and carbapenem resistance by Gram-negative bacteria has rendered some hospital-acquired pathogens impossible to treat. The resistance mechanisms employed are sophisticated and very difficult to overcome. Unless alternative treatment regimes are initiated soon, our inability to treat totally resistant bacteria will halt other developments in medicine. In the community, Gram-positive bacteria responsible for pneumonia could become totally resistant leading to increased mortality from this common infection, which would have a more immediate impact on our current lifestyles

Clonal diversity of Acinetobacter baumannii from diabetic patients in Saudi Arabian hospitals

Carbapenem-resistant Acinetobacter baumannii (CR-AB) represents a major health-care problem causing high rates of morbidity and mortality. This study investigated the clonality of CR-AB isolated from diabetic patients from different regions in Saudi Arabia as well as the relatedness of the β lactamases genes. A total of 64 non-repetitive CR-AB clinical isolates were collected from 16 different regions in Saudi Arabia from intensive care patients. Isolates were identified phenotypically by Vitek 2 compact system and genotypically by amplification of blaOXA-51-like gene. The target sequences were amplified by PCR and the clonal diversity of the isolates was explored by PFGE. Resistance studies revealed that the prevalence of imipenem and meropenem resistance was 92% and 96%, respectively, while the vast majority of the isolates were susceptible to tigecycline and colistin. In addition, blaVIM and blaOXA-23 were the most prevalent genes in the isolates under investigation while ISAba1 was the most dominant insertion sequence. PFGE results showed 13 clusters; clone H was dominant comprising 20 isolates from four hospitals followed by clones C and F comprising 11 isolates each from 3 and 6 hospitals, respectively. Moreover, the current study signified the clonal diversity of CR-AB in Saudi Arabia and showed the ability of some clones to infect patients in many different cities

Dissemination of multiple carbapenem-resistant clones of Acinetobacter baumannii in the Eastern District of Saudi Arabia

It has previously been shown that carbapenem-resistant Acinetobacter baumannii are frequently detected in Saudi Arabia. The present study aimed to identify the epidemiology and distribution of antibiotic resistance determinants in these bacteria. A total of 83 A. baumannii isolates were typed by pulsed-field gel electrophoresis (PFGE), and screened by PCR for carbapenemase genes and insertion sequences. Antibiotic sensitivity to imipenem, meropenem, tigecycline, and colistin were determined. Eight different PFGE groups were identified, and were spread across multiple hospitals. Many of the PFGE groups contained isolates belonging to World-wide clone 2. Carbapenem resistance or intermediate resistance was detected in 69% of isolates. The blaVIM gene was detected in 94% of isolates, while blaOXA–23–like genes were detected in 58%. The data demonstrate the co-existence and wide distribution of a number of clones of carbapenem-resistant A. baumannii carrying multiple carbapenem-resistance determinants within hospitals in the Eastern Region of Saudi Arabia

Draft Genome Sequence of a Multidrug-Resistant Acinetobacter baumannii Strain from Chile

Date of Acceptance: 20/05/2015 Copyright © 2015 Opazo et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported license. ACKNOWLEDGMENTS This work was supported through funds granted by the Chilean National Commission for Scientific and Technological Research (CONICYT) and by the National Fund for Scientific and Technological Development (FONDECYT) of Chile (project 3150286).Peer reviewedPublisher PD

The in vitro effects of faropenem on lower respiratory tract pathogens isolated in the United Kingdom

Faropenem is a new oral penem with a structure different from current β-lactams including carbapenems. The susceptibility of Streptococcuspneumoniae, Haemophilus influenzae and Moraxella catarrhalis to faropenem, a macrolide, a β-lactam, a β-lactam/β-lactamase inhibitor combination and two fluoroquinolones was investigated. S. pneumoniae was the most susceptible of the three species to faropenem. The MIC90s of faropenem against M. catarrhalis and H. influenzae were 0.5 and 1 mg/l, respectively. They were similar to amoxiclav (MIC 90s of 0.25 and 0.5 mg/l). The quinolones showed strong activity against H. influenzae. A cluster analysis of the activities of amoxycillin and faropenem demonstrated a direct relationship between the two antimicrobial agent's activities and resistance profiles against both S. pneumoniae and H. influenzae