Antimicrobial susceptibility of bacteria causing urinary tract infections in Latin American hospitals: results from the SENTRY Antimicrobial Surveillance Program (1997)

Objectives: To evaluate the antimicrobial susceptibility patterns among 469 pathogens isolated as a significant cause of urinary tract infections in 10 Latin American medical centers.
Methods: Consecutively collected isolates were susceptibility tested by broth microdilution methods, and selected isolates were characterized by molecular typing methods.
Results: Escherichia coli and Klebsiella spp. isolates revealed high rates of resistance to broad-spectrum penicillins and to fluoroquinolones. Ceftazidime MICs of ≥2 mg/L, suggesting the production of extended-spectrum β-lactamases (ESBLs), were observed in 37.7% of K. pneumoniae and 8.3% of Escherichia coli isolates. Enterobacter spp. isolates were characterized by high resistance rates to ciprofloxacin (35%) and to ceftazidime (45%), but they generally remained susceptible to cefepime (95% susceptible). Pseudomonas aeruginosa and Acinetobacter spp. were highly resistant to ciprofloxacin and ceftazidime. Imipenem was active against 80% of P. aeruginosa and 93% of Acinetobacter spp. isolates.
Conclusions: Our results demonstrate a high level of resistance to various classes of antimicrobial agents among isolates causing nosocomial urinary tract infections in Latin American hospitals. Clonal dissemination of ESBL-producing K. pneumoniae strains was infrequent.     

Current Strategy for Local- to Global-Level Molecular Epidemiological Characterisation of Global Antimicrobial Resistance Surveillance System Pathogens

The prime goal of molecular epidemiology is to identify the origin and evolution of pathogens, which can potentially influence the public health worldwide. Traditional methods provide limited information which is not sufficient for outbreak investigation and studying transmission dynamics. The recent advancement of next-generation sequencing had a major impact on molecular epidemiological studies. Currently, whole-genome sequencing (WGS) has become the gold standard typing method, especially for clinically significant pathogens. Here, we aimed to describe the application of appropriate molecular typing methods for global antimicrobial resistance surveillance system pathogens based on the level of discrimination and epidemiological settings. This shows that sequence-based methods such as multi-locus sequence typing (MLST) are widely used due to cost-effectiveness and database accessibility. However, WGS is the only method of choice for studying Escherichia coli and Shigella spp. WGS is shown to have higher discrimination than other methods in typing Klebsiella pneumoniae, Acinetobacter baumannii and Salmonella spp. due to its changing accessory genome content. For Gram positives such as Streptococcus pneumoniae, WGS would be preferable to understand the evolution of the strains. Similarly, for Staphylococcus aureus, combination of MLST, staphylococcal protein A or SCCmec typing along with WGS could be the choice for epidemiological typing of hospital- and community-acquired strains. This review highlights that combinations of different typing methods should be used to get complete information since no one standalone method is sufficient to study the varying genome diversity.     

The changing epidemiology of bacteraemias in Europe: trends from the European Antimicrobial Resistance Surveillance System

We investigated bacteraemia trends for five major bacterial pathogens, Staphylococcus aureus, Escherichia coli, Streptococcus pneumoniae, Enterococcus faecalis and Enterococcus faecium, and determined how expanding antimicrobial resistance influenced the total burden of bacteraemias in Europe. Aetiological fractions of species and antibiotic phenotypes were extracted from the European Antimicrobial Resistance Surveillance System (EARSS) database for laboratories, which consistently reported between 2002 and 2008. Trend analyses used generalized linear models. Robustness of results was assessed by iterative analysis for different geographic regions. From 2002 to 2008, the overall number of reports increased annually by 6.4% (95% confidence interval (CI) 6.2–6.5%), from 46 095 to 67 876. In the subset of laboratories providing denominator information, the overall incidence increased from 0.58/1000 patient-days to 0.90/1000 patient-days (7.2% per year; 95% CI 6.9–7.5%). The frequency of reported bacteraemia isolates of S. aureus and Streptococcus pneumoniae increased moderately, while increase in E. coli and Enterococcus faecium was more pronounced. Bacteraemias caused by methicillin-resistant S. aureus increased until 2005 (7.6% per year; 95% CI 6.1–9.1%), and then decreased (–4.8% per year; 95% CI –6.1 to –3.5%), whereas the number attributable to methicillin-sensitive S. aureus increased continuously (3.4% per year; 95% CI 3.0–3.7). Increasing rates of E. coli were mainly caused by antibiotic-resistant phenotypes. Our data suggest that the burden of bacterial bloodstream infection has been increasing for all species during EARSS surveillance. Trends were mainly driven by resistant strains and clearly dissociated between resistant and susceptible isolates. It appears that infections with resistant clones add to rather than replace infections caused by susceptible bacteria. As a consequence, expansion of antibiotic resistance creates an additional strain on healthcare systems.     

Resistance to β-lactams among blood isolates of Salmonella spp. in European hospitals: results from the SENTRY Antimicrobial Surveillance Program 1997–98

The susceptibility to β -lactams and the β -lactamase content of 110 Salmonella spp. blood isolates collected during 1997–98 in 19 European centers participating in the SENTRY Surveillance Program were studied. Thirty-one isolates (28%) were resistant to penicillins, due to production of TEM-1 (27 isolates), OXA-1 (three isolates) or TEM-1 + OXA-1 (one isolate). All OXA-1 producers and 10 TEM-1-producing isolates were also resistant to penicillin–clavulanic acid combinations. In the latter isolates, this phenotype was associated with increased production of TEM-1. Sixteen TEM-1-producing Salmonella Enteritidis isolates and one OXA-1-producing S. Typhimurium isolate were able to transfer β -lactam resistance by conjugation.