Effectiveness of a hospital-wide selective screening programme for methicillin-resistant Staphylococcus aureus (MRSA) carriers at hospital admission to prevent hospital-acquired MRSA infections

Screening of potential MRSA-positive patients at hospital admission is recommended in German and international guidelines. This policy has been shown to be effective in reducing the frequency of nosocomial MRSA transmissions in the event of an outbreak, but the influence of screening on reducing hospital-acquired MRSA infections in a hospital setting where MRSA is endemic is not yet well-documented. This study describes the effect of hospital-wide screening of defined risk groups in a 700-bed acute care hospital during a period of 19 months. In a cohort study with a 19-month control period, the frequencies of hospital-acquired MRSA infections were compared with and without screening. In the control period, there were 119 MRSA-positive patients, of whom 48 had a hospital-acquired MRSA infection. On the basis of this frequency, a predicted total of 73.2 hospital-acquired MRSA infections was calculated for the screening period, but only 52% of the expected number (38 hospital-acquired MRSA infections) were observed, i.e., 48% of the predicted number of hospital-acquired MRSA infections were prevented by the screening programme. The screening programme was performed with minimal effort and can therefore be recommended as an effective measure to help prevent hospital-acquired MRSA infections.     

The role of telavancin in the treatment of MRSA infections in hospital

Background: Serious infections caused by Gram-positive bacteria, particularly multi-drug resistant, are an important cause of morbidity and mortality in patients admitted to intensive care units. Thus, new antibiotics covering these pathogens are urgently needed. Objective: To review characteristics of telavancin, a novel antibiotic intended to use for treating infections caused by difficult Gram-positive bacteria, such as Staphylococcus aureus, resistant to meticillin or vancomycin, multi-drug-resistant Streptococcus pneumoniae or glycopeptide-resistant enterococci. Methods: The studies on microbiological activity, clinical efficacy and safety of telavancin were reviewed. Results/conclusion: Telavancin is a lipoglycopeptide administered intravenously once-daily and excreted with urine. It proved to be microbiologically active against numerous Gram-positive pathogens including drug-resistant staphylococci, enterococci and pneumococci. Large randomized Phase II and III clinical trials on efficacy and safety of telavancin in treating complicated skin and skin structure infections reported telavancin to be non-inferior to standard treatment (mostly vancomycin). Preliminary data on telavancin in hospital-acquired pneumonia, including ventilator-associated pneumonia, documented that telavancin was efficacious for this indication. Overall incidence of adverse events was similar for telavancin and the comparator arms. Mild and transient disgeusia, nausea and vomiting resulted to be more frequent in telavancin group. Increase in creatinine values was also observed in telavancin arm.     

Corynebacterium species as one of the major causative pathogens of bacterial pneumonia

Recent advances using molecular methods, matrix-assisted laser desorption ionization time of flightmass spectrometry, and next-generation sequencers enable rapid and precise detection of bacterial species in the clinical samples, revealing bacterial diversities in the human body. Corynebacterium species are Gram-positive bacilli, which can cause pneumonia and have been reported as causative pathogens of lower respiratory tract infections since the 1970's. However, Corynebacterium spp. may be recognized and sorted as part of normal respiratory flora on Gram staining and culture, resulting in clinical under-recognition as pathogenic bacteria.The results of the clone library method using bacterial 16S ribosomal RNA gene sequence analysis in Japanese patients with hospital-acquired pneumonia revealed that bronchoalveolar lavage fluid obtained from the lung lesions contained 11.8% Corynebacterium spp., which was the second most predominant bacterial phylotype. Additionally, among patients in whom Corynebacterium spp. were detected, C. simulans was most commonly detected followed by C. striatum. In addition, almost half of the patients in whom C. simulans was detected was monophylotypic infection and/or co-detection of C. simulansand C. striatum. Further clinical information is expected on corynebacteria as pathogens of lower respiratory tract infection.     

Bed occupancy rates and hospital-acquired infections—should beds be kept empty?

There is growing evidence that bed occupancy (BO) rates, overcrowding and understaffing influence the spread of hospital-acquired infections (HAIs). In this article, a systematic review of the literature is presented, summarizing the evidence on the adverse effects of high BO rates and overcrowding in hospitals on the incidence of HAIs. A Pubmed database search identified 179 references, of which 44 were considered to be potentially relevant for full-text review. The majority (62.9%) focused on methicillin-resistant Staphylococcus aureus-associated infection or colonization. Only 12 studies were found that provided a statistical analysis of the impact of BO on HAI rates. The median BO rate of the analysed studies was 81.2%. The majority of studies (75%) indicated that BO rates and understaffing directly influence the incidence of HAIs. Only three studies showed no significant association between BO rates and the incidence of HAIs. Interestingly, only one of the included studies detected a seasonal trend in the BO rate. The present review shows an association between BO rates and the spread of HAIs in various settings. Because the evidence on this topic is limited, we conclude that further research is needed in order to analyse the rationale of a threshold BO rate, because keeping beds empty is comparatively costly.     

Mechanisms of antimicrobial resistance among hospital-associated pathogens

Introduction: The introduction of antibiotics revolutionized medicine in the 20th-century permitting the treatment of once incurable infections. Widespread use of antibiotics, however, has led to the development of resistant organisms, particularly in the healthcare setting. Today, the clinician is often faced with pathogens carrying a cadre of resistance determinants that severely limit therapeutic options. The genetic plasticity of microbes allows them to adapt to stressors via genetic mutations, acquisition or sharing of genetic material and modulation of genetic expression leading to resistance to virtually any antimicrobial used in clinical practice.

Areas covered: This is a comprehensive review that outlines major mechanisms of resistance in the most common hospital-associated pathogens including bacteria and fungi.

Expert commentary: Understanding the genetic and biochemical mechanisms of such antimicrobial adaptation is crucial to tackling the rapid spread of resistance, can expose unconventional therapeutic targets to combat multidrug resistant pathogens and lead to more accurate prediction of antimicrobial susceptibility using rapid molecular diagnostics. Clinicians making treatment decisions based on the molecular basis of resistance may design therapeutic strategies that include de-escalation of broad spectrum antimicrobial usage, more focused therapies or combination therapies. These strategies are likely to improve patient outcomes and decrease the risk of resistance in hospital settings.     

Appropriate Antibiotic Administration in Critically Ill Patients with Pneumonia

Inappropriate initial antibiotics for pneumonia infection are usually linked to extended intensive care unit stay and are associated with an increased risk of mortality. This study evaluates the impact of inappropriate initial antibiotics on the length of intensive care unit stay, risk of mortality and the co-predictors that influences these outcomes. This retrospective study was conducted in an intensive care unit of a teaching hospital. The types of pneumonia investigated were hospital-acquired pneumonia and ventilator-associated pneumonia. Three different time points were defined as the initiation of appropriate antibiotics at 24 h, between 24 to 48 h and at more than 48 h after obtaining a culture. Patients had either hospital-acquired pneumonia (59.1%) or ventilator-associated pneumonia (40.9%). The length of intensive care unit stay ranged from 1 to 52 days (mean; 9.78±10.02 days). Patients who received appropriate antibiotic agent at 24 h had a significantly shorter length of intensive care unit stay (5.62 d, P<0.001). The co-predictors that contributed to an extended intensive care unit stay were the time of availability of susceptibility results and concomitant diseases, namely cancer and sepsis. The only predictor of intensive care unit death was cancer. The results support the need for early appropriate initial antibiotic therapy in hospital-acquired pneumonia and ventilator-associated pneumonia infections.     

FDA“医院获得性细菌性肺炎和呼吸机相关性细菌性肺炎：供企业用治疗药物开发指导原则”介绍

美国食品药品监督管理局（FDA）于2020年6月发布了“医院获得性细菌性肺炎和呼吸机相关性细菌性肺炎：供企业用治疗药物开发指导原则”。该指导原则阐述了治疗这类疾病的抗菌药物临床研究的一般原则和具体试验设计的建议。介绍该指导原则的主要内容,期待对中国“医院获得性细菌性肺炎/呼吸机相关细菌性肺炎抗菌药物临床试验技术指导原则（征求意见稿）”的定稿和促进这类药物的研究有帮助。     

恶性肿瘤患者医院获得性真菌感染的病原学分布与耐药性分析

目的了解恶性肿瘤患者医院获得性真菌感染的菌种分布,诱发真菌感染的危险因素及对常用抗真菌药物的耐药性,为临床治疗真菌感染提供依据。方法对2012年1月至2013年12月送检的324例恶性肿瘤患者标本进行真菌培养及药敏试验。结果 324例恶性肿瘤患者标本中共检出真菌96株,感染率为29.6%。其中以呼吸道感染最多,占74.0%;菌种以白假丝酵母菌为首,占67.7%,其次是热带假丝酵母菌,占14.6%。抗菌药物的滥用、大量激素的使用及侵入性操作等是真菌感染的危险因素。5种假丝酵母菌对伊曲康唑的耐药率最高,对5-氟胞嘧啶和两性霉素B全敏感。结论常见假丝酵母菌属对常用抗真菌药物已具有一定的耐药性,临床应加强监测与控制,并根据药敏试验结果合理选用抗真菌药物。     

新生儿社区和院内获得性肺炎的病原学特点及药敏分析

目的探讨新生儿社区获得性肺炎(CAP)和院内获得性肺炎(HAP)的病原分布和药敏情况。方法回顾性分析2010年1月—2014年12月因新生儿肺炎住院且痰培养阳性新生儿的临床资料。结果在3 564例CAP新生儿中共检出病原微生物4 383株,其中细菌3 584株、病毒771、真菌7株及非典型病原体21株。细菌以革兰阴性菌为主,3 045株(85.0%),细菌中排名前三的为肺炎克雷伯菌、大肠埃希菌及金黄色葡萄球菌;病毒以呼吸道合胞病毒为主,693株(89.9%)。在344例HAP新生儿中共检出病原微生物424株,其中细菌402株,真菌17株,呼吸道合胞病毒5株。细菌均为革兰阴性菌,未发现革兰阳性菌,排名前三的为肺炎克雷伯菌、大肠埃希菌及鲍曼不动杆菌。CAP与HAP新生儿中革兰阴性菌产ESBLs菌分别为26.9%、46.8%,差异有统计学意义(P?0.05)。CAP、HAP的肺炎克雷伯菌和大肠埃希菌均对阿米卡星、碳青霉烯类高度敏感。HAP的肺炎克雷伯菌对常用抗菌药物(除阿米卡星、喹诺酮类外)的敏感性普遍低于CAP,差异有统计学意义(P?0.05);HAP的大肠埃希菌对常用抗菌药物(除阿米卡星、喹诺酮类及碳青霉烯类外)的敏感性普遍低于CAP,差异有统计学意义(P?0.05)。此外,还发现耐碳青霉烯类的肠杆菌。结论新生儿肺炎病原菌以革兰阴性菌为主,其中CAP以肺炎克雷伯菌、大肠埃希菌及金黄色葡萄球菌为主,HAP以肺炎克雷伯菌、大肠埃希菌及鲍曼不动杆菌为主。HAP致病菌的产酶率和耐药性均普遍高于CAP,且有多重耐药趋势。