Bacterial Resistance---Challenges and Strategies / 医药导报

Bacterial resistance to antibiotics is currently a serious health concern.According to the data from the surveil-lance of bacterial resistance in China ( CHINET) ,the isolation rates of gram-negative bacteria have been rising annually. Among the gram-negative organisms, the isolation rate of Carbapenem-resistant enterobacteriaceae, especially extensive drug-resistant strains,has been increasing rapidly.The isolation rate of extensive drug-resistant or pandrug-resistant non-fermenting bacteria,es-pecially Acinetobacter baumanii,is still relatively high.These extensive drug-resistant gram-negative bacteria cause high mortality, which has drawn great attention in clinical settings.On the part of multidrug-assistant gram-positive bacteria,the isolation rate of vancomycin-resistant enterococci remains stable but rates of methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci are still high.Staphylococcal strains have not yet been found resistant to vancomycin in China.Understanding the epi-demiology of local drug-resistant bacteria facilitates the development of appropriate antibiotic strategies. The mortality of patients with severe infection may be improved by early use of antibiotics and appropriate de-escalation therapy.Rational use of antibiotics and recognition of the influence factors,such as antibiotic-induced endotoxin release,may maximize the efficacy of antibiotics and minimize the adverse reactions.

Molecular study on methicillin-resistant Staphylococcus aureus strains isolated from dogs and associated personnel in Jordan

Objective:To determine the prevalence, genetic relatedness, and pattern of antimicrobial susceptibility in methicillin-resistant Staphylococcus aureus (S. aureus) (MRSA) isolated from household dogs, farm dogs, and stray dogs, compared to isolates from their associated personnel. Methods: MRSA was isolated from 250 nasal swabs (150 swabs from dogs and 100 swabs from humans). PCR assays were used to detect the presence of both the nuc and mecA genes, which confirmed the identity of S. aureus isolates and the presence of methicillin resistance, respectively. Disk diffusion was used to determine the antibiotic susceptibility against 15 antimicrobial agents along with an E-test that determined the minimum inhibitory concentration for oxacillin. Pulsed field gel electrophoresis was conducted to determine the genetic relatedness of MRSA isolates from dogs to those from associated and unassociated personnel. Results:The prevalence of S. aureus in dogs and humans was 12.7%and 10.0%respectively, while the prevalence of MRSA isolates in dogs and humans was 5.3%and 5.0%, respectively. The prevalence of MRSA isolates in household dogs, farm dogs, and stray dogs was 7.8%, 4.7%, and 0.0%, respectively. MRSA isolates demonstrated a significantly higher rate of multi-resistance against three or more antimicrobial agents than methicillin-susceptible S. aureus (MSSA). Trimethoprim-sulphamethoxazole and chloramphenicol were the most effective antibiotics against all MRSA isolates. Pulsed field gel electrophoresis revealed a strong association between dog MRSA isolates and MRSA isolates from strongly associated personnel. Conclusions:MRSA is prevalent in house dogs, as well as in dog rearing centers and among their strongly associated personnel. A strong association was found between the MRSA isolates from dogs and those from humans who are in close contact. In addition, MRSA isolates showed a high rate of multi-resistance compared to MSSA isolates.

Healthcare-associated methicillin-resistant Staphylococcus aureus infec-tion outbreak in neurosurgical intensive care unit / 中国感染控制杂志

Objective To investigate the causes of an outbreak of healthcare-associated infection with methicillin-resist-ant Staphylococcus aureus (MRSA)in a neurosurgical intensive care unit(NSICU).Methods Epidemiological investigation on 8 patients with lower respiratory tract infection (LRTI)in a NSICU between June 15 and June 28,2104 were performed by combination methods of prospective and retrospective survey.Results The attack rate of MRSA LRTI in NSICU patients was 22.86%,a total of 16 MRSA isolates were detected from patients’clinical specimens,nasal vestibule,as well as hospital surroundings during the period,pulsed-field gel electrophoresis (PFGE)result revealed that infection outbreak was caused by two subtypes of MRSA;risk factors analysis showed that long length of stay in ICU and aspiration of spu-tum through bronchoscopy were risk factors for MRSA LRTI.Conclusion Contamination of bronchoscope was the key factor for this epidemic spread of healthcare-associated MRSA infection.

Prevalence of methicillin-resistant Staphylococcus aureus in a University Hospital in the South of Brazil

Methicillin-resistant Staphylococcus aureus (MRSA) stand out as one of the main agents causing nosocomial and community infections. This retrospective study aimed to analyze the MRSA predominance in a university hospital in the south of Brazil and it was carried out for five years (from 2007 to 2011). 616 MRSA (33,3% of the total) were isolated and an important reduction in the MRSA predominance was observed along the study. Although it was registered a reduction in the MRSA predominance, male adult patients (41-70 years old), who were in the Medical Clinic and Adult ICU, had the highest infection rates and concerning MRSA isolates rates, these were higher in blood and tracheal aspirates. In conclusion, studies of this type are becoming relevant to recognize pathogens like MRSA and to determine its predominance.

Staphylococcus aureus resistentes à meticilina (MRSA) destacam-se mundialmente como um dos mais frequentes patógenos nosocomiais e comunitários. Este estudo retrospectivo teve por objetivo analisar a prevalência de MRSA em um hospital universitário no sul do Brasil. Durante cinco anos (2007 a 2011), 616 MRSA (33,3% do total de S. aureus) foram isolados, sendo que sua frequência de isolamento apresentou considerável redução no decorrer do estudo. Nossos resultados demonstraram que as maiores taxas de isolamento dos MRSA ocorreram em amostras de sangue e secreção traqueal. As infecções prevaleceram em pacientes adultos (41 a 70 anos), do sexo masculino, internados na Clínica Médica e UTI adulto. Estudos como este se tornam importantes para o reconhecimento de patógenos resistentes, como o MRSA, e para a determinação da sua prevalência.

Implementation of vancomycin dosing nomogram in an electronic prescribing system: an innovative tool in antibiotic stewardship

Vancomycin (VAN) is the gold standard therapy for Methicillin-resistant Staphylococcus aureus (MRSA) infections such as bacteremia and endocarditis. However, VAN suboptimal dosing for serious infections caused by S. aureus isolates that have elevated minimum inhibitory concentration (MIC), could be associated with poor outcome. Better understanding of VAN pharmacokinetics and pharmacodynamics (PK/PD) has led to the creation of new recommendations with optimized dosing regimens for the treatment of MRSA infections. For severe infectious, such as pneumonia and endocarditis, a VAN serum trough concentration of 15-20 mg/L at the steady state should be targeted. The aim of this study was to show how a nomogram with updated VAN dosing was devised and how it was implemented in the electronic prescribing (e-prescribing) system of a teaching hospital. VAN loading dose and maintenance doses were calculated from a pharmacokinetic equation using basic parameters: weight, estimated creatinine clearance, as well as peak and trough serum concentrations. The implementation of the VAN dosing nomogram in the hospital e-prescribing system definitively changed the long-standing medical prescription fallacy of "same dose fits all". Finally, this computer-based electronic program has allowed a wide-ranging intervention and should be recognized as a powerful tool for implementation in antimicrobial stewardship programs.

Vancomicina (VAN) é utilizada como primeira escolha na terapia de infecções causadas por Staphylococcus aureus resistentes à meticilina (MRSA), como bacteremia e endocardite. Entretanto, o aumento na concentração inibitória mínima (CIM) de isolados de S. aureus e doses subterapêuticas de VAN podem estar associados à falha terapêutica. Para o melhor entendimento sobre o perfil farmacocinético e farmacodinâmico (PK/PD) da VAN foram elaboradas novas recomendações para terapia de infecções causadas por MRSA. Para terapia de infecções graves, como pneumonia e endocardite, a concentração sérica do vale de VAN de 15-20 mg/L no estado de equilíbrio dinâmico deve ser o alvo. O objetivo do estudo foi desenvolver um nomograma com doses atualizadas de VAN e demonstrar como ele foi implementado no sistema de prescrição eletrônica em um Hospital Universitário. As doses de ataque e manutenção foram calculadas a partir de equações farmacocinéticas, utilizando parâmetros fundamentais: peso, depuração de creatinina, concentrações séricas do pico e do vale. A implementação de um nomograma de doses de VAN em um sistema de prescrição eletrônica modificou definitivamente o inadequado hábito de que "a mesma dose cabe em todos". Finalmente, esta abrangente ferramenta tecnológica deve ser considerada como uma robusta estratégia num programa de uso racional de antibióticos.