Daptomycin-Induced Hyperkalemia as an Early Sign of Rhabdomyolysis in a Diabetic Patient

Daptomycin is a lipopeptide antibiotic that is active against vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). It is less nephrotoxic than vancomycin. It has a unique bactericidal mechanism through destruction of bacterial membrane potential. However, one of the most clinically relevant adverse effects of daptomycin is reversible myopathy, especially when daptomycin is used in high doses. Here, we present a case of a patient with rhabdomyolysis preceded by hyperkalemia associated with daptomycin use. Soon after daptomycin administration, hyperkalemia was noticed before the acute rise in creatinine phosphokinase (CPK). The serum levels of potassium and CPK returned to normal after daptomycin was stopped which suggested the causal relationship between hyperkalemia and myopathy and daptomycin use. To our knowledge, this is the second case of hyperkalemia related to daptomycin use.

Vancomycin-resistant Enterococcus faecium Empyema in an Asplenic Patient

Enterococcal empyema is a rare complication of pneumonia. We report the case of a 67-year-old asplenic man with pneumonia complicated by respiratory failure and empyema requiring decortication and prolonged chest tube drainage. Cultures of the empyema were initially negative, but later grew vancomycin-resistant Enterococcus faecium (VRE), which was successfully treated with linezolid. To our knowledge, this is only the second reported case of an empyema caused by VRE that was not associated with an intra-abdominal infection. We suspect superinfection due to airway or chest tube contamination as the most likely mechanism of infection. Physicians should consider multi-drug resistant organisms such as VRE in patients with empyema that fail to resolve with chest tube drainage and broad-spectrum antibiotics.

Improving hospital hygiene to reduce the impact of multidrug-resistant organisms in health care--a prospective controlled multicenter study

BACKGROUND

Nosocomial infections are the most common complication during inpatient hospital care. An increasing proportion of these infections are caused by multidrug-resistant organisms (MDROs). This report describes an intervention study which was designed to address the practical problems encountered in trying to avoid and treat infections caused by MDROs. The aim of the HARMONIC (Harmonized Approach to avert Multidrug-resistant Organisms and Nosocomial Infections) study is to provide comprehensive support to hospitals in a defined study area in north-east Germany, to meet statutory requirements. To this end, a multimodal system of hygiene management was implemented in the participating hospitals.

METHODS/DESIGN

HARMONIC is a controlled intervention study conducted in eight acute care hospitals in the 'Health Region Baltic Sea Coast' in Germany. The intervention measures include the provision of written recommendations on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci (VRE) and multi-resistant Gram-negative bacteria (MRGN), supplemented by regional recommendations for antibiotic prescriptions. In addition, there is theoretical and practical training of health care workers (HCWs) in the prevention and handling of MDROs, as well as targeted and critically gauged applications of antibiotics. The main outcomes of the implementation and analysis of the HARMONIC study are: (i) screening rates for MRSA, VRE and MRGN in high-risk patients, (ii) the frequency of MRSA decolonization, (iii) the level of knowledge of HCWs concerning MDROs, and (iv) specific types and amounts of antibiotics used. The data are predominantly obtained by paper-based questionnaires and documentation sheets. A computer-assisted workflow-based documentation system was developed in order to provide support to the participating facilities. The investigation includes three nested studies on risk profiles of MDROs, health-related quality of life, and cost analysis. A six-month follow-up study investigates the quality of life after discharge, the long-term costs of the treatment of infections caused by MDROs, and the sustainability of MRSA eradication.

DISCUSSION

The aim of this study is to implement and evaluate an area-wide harmonized hygiene program to control the nosocomial spreading of MDROs. Comparability between the intervention and control group is ensured by matching the hospitals according to size (number of discharges per year/number of beds) and level of care (standard or maximum). The results of the study may provide important indications for the implementation of regional MDRO management programs.

Identification of vancomycin-resistant enterococci clones and inter-hospital spread during an outbreak in Taiwan

BACKGROUND

In 2003, nosocomial infections caused by vancomycin-resistant enterococci (VRE) occurred rarely in Taiwan. Between 2003 and 2010, however, the average prevalence of vancomycin resistance among enterococci spp. increased from 2% to 16% in community hospitals and from 3% to 21% in medical centers of Taiwan. We used molecular methods to investigate the epidemiology of VRE in a tertiary teaching hospital in Taiwan.

METHODS

Between February 2009 and February 2011, rectal samples and infection site specimens were collected from all inpatients in the nephrology ward after patient consent was obtained. VRE strain types were determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

RESULTS

A total of 59 vanA gene-containing VRE isolates (1 per patient) were obtained; 24 originated from rectal sample surveillance of patients who exhibited no symptoms (22 Enterococcus faecium and 2 Enterococcus faecalis), and 35 had developed infections over 3 days after admission (32 E. faecium, 2 E. faecalis, and 1 Enterococcus durans). The 59 VRE isolates demonstrated vancomycin minimum inhibitory concentrations (MICs) of ≥256 μg/m. The MIC range for linezolid, tigecycline, and daptomycin was 0.25-1.5 μg/mL, 0.032-0.25 and 1-4 μg/mL, respectively. For 56 isolates, the MIC for teicoplanin was >8 μg/mL. The predominant types in the nephrology ward were MLST types 414, 78, and18 as well as PFGE types A, C, and D.

CONCLUSION

VREs are endemic in nephrology wards. MLST 414 is the most predominant strain. The increase VRE prevalence is due to cross-transmission of VRE clones ST 414,78,18 by undetected VRE carriers. Because similar VRE STs had been reported in a different hospital of Taiwan, this finding may indicate inter-hospital VRE spread in Taiwan. Active surveillance and effective infection control policies are important controlling the spread of VRE in high risk hospital zones. All endemic VRE strains are resistant to teicoplanin but are sensitive to daptomycin, linezolid, and tigecycline.

Prevalence and risk factors for VRE colonisation in a tertiary hospital in Melbourne, Australia: a cross sectional study

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) has been established as a significant health-care associated problem since its first isolation in Australia in 1994. In this study, we measured the point prevalence and identified risk factors associated with vanB VRE colonisation in a tertiary care hospital in Melbourne, Australia where VRE has been endemic for 15 years.

METHODS

A hospital-wide point prevalence survey was conducted on October 13, 2008 with colonisation detected using rectal swab culture. Patient's demographic and medical information was collected through a review of medical records. Factors associated with VRE colonisation in univariate analysis were included in multivariate logistic regression model to adjust for confounding.

RESULTS

The prevalence of VRE colonisation on the day of screening was 17.5% (95% CI, 13.7 to 21.9). VRE was detected from patients in each ward with the prevalence ranging from 3% to 29%. Univariate analysis showed the use of any antibiotic, meropenem, ciprofloxacin, diarrhoea and longer length of hospital stay were associated with increased risk of VRE colonisation (p<0.05). However, age, sex, proximity to VRE positive cases, use of other antibiotics including cephalosporins, vancomycin were not associated with increased risk (P>0.05). Multivariate analysis showed the exposure to meropenem (p=0.004), age (≥65 years) (p=0.036) and length of stay ≥7 days (p<0.001) as independent predictors of VRE colonisation.

CONCLUSION

Our study suggests that exposure to antibiotics may have been more important than recent cross transmission for a high prevalence of vanB VRE colonisation at our hospital.

Inactivation of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) on various environmental surfaces by mist application of a stabilized chlorine dioxide and quaternary ammonium compound-based disinfectant

Contaminated environmental surfaces are important reservoirs in the transmission of many human pathogens. Although several options exist for disinfecting contaminated environmental surfaces, few are compatible with use on both hard smooth non-porous (hard) and soft porous surfaces (soft) while still offering significant disinfection of the contaminating organisms. This study evaluated the efficacy of mist application of a stabilized chlorine dioxide and quaternary ammonium compound-based disinfectant (Cryocide20) for inactivation of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) on various environmental surfaces. MRSA and VRE were applied to hard and soft surfaces (glass, steel, tile, carpet, and cotton fabric), allowed to dry, and exposed to a uniform mist application of the disinfectant solution. After 1 hr of contact time, the residual disinfectant was neutralized, and the bacteria were recovered and enumerated on brain heart infusion (BHI) agar. Reduction of both test bacteria was observed on most of the hard and soft surfaces tested. Log(10) reduction of the organisms tended to be higher on steel, tile, and carpet than glass or cotton. Overall, these results suggest that mist application of Cryocide20 disinfectant may be an effective option for reduction of low levels of infectious bacterial pathogens from contaminated environmental surfaces.

Daptomycin in bone and joint infections: a review of the literature

INTRODUCTION

To review the pharmacology, pharmacokinetics, efficacy, and safety of daptomycin, a novel antibiotic for the treatment of bone and joint infections, a literature search of relevant articles was conducted.

MATERIALS AND METHODS

A PubMed/MEDLINE search (1990-April 2008) to identify relevant English-language literature was conducted. Search terms included bone and joint infection, osteomyelitis, daptomycin, and methicillin-resistant Staphylococcus aureus (MRSA). Additional articles were identified by reviewing the bibliographies of articles cited. Programs and abstracts from infectious disease meetings were searched, and prescribing information of antibiotics indicated for bone and joint infections consulted. All articles identified from data sources published in English were evaluated.

RESULTS

Caused primarily by Gram-positive pathogens such as S. aureus and, to a lesser extent, Enterococcus faecalis, bone and joint infections are difficult to treat successfully. Surgical intervention and prolonged courses of antibiotics are frequently required, and failure of first-line antibiotic therapy is common. The emergence of S. aureus strains with reduced susceptibility to vancomycin, the longstanding gold standard for bone and joint infections, has complicated the clinical scenario. Few randomized trials comparing the efficacy of different antibiotics for bone and joint infections exist. Daptomycin, a novel intravenous lipopeptide antibiotic, has shown potent in vitro activity against a broad spectrum of Gram-positive bacteria, including many resistant pathogens commonly associated with bone and joint infections such as MRSA and vancomycin-resistant E. faecalis. Early clinical investigation of daptomycin in bone and joint infections unresponsive to antibiotics, such as vancomycin, has found a cure rate of approximately 80%, with a low incidence of adverse events and drug resistance.

CONCLUSION

Further studies are warranted to determine if limited clinical evidence, described in individual case reports and a daptomycin-specific retrospective registry, suggests daptomycin is a promising option for patients with bone and joint infections such as MRSA osteomyelitis.

Method revealing bacterial cell-wall architecture by time-dependent isotope labeling and quantitative liquid chromatography/mass spectrometry

The molecular details of the biosynthesis and resulting architecture of the bacterial cell wall remain unclear but are essential to understanding the activity of glycopeptide antibiotics, the recognition of pathogens by hosts, and the processes of bacterial growth and division. Here we report a new strategy to elucidate bacterial cell-wall architecture based on time-dependent isotope labeling of bacterial cells quantified by liquid chromatography/accurate mass measurement mass spectrometry. The results allow us to track the fate of cell-wall precursors (which contain the vancomycin-binding site) in Enterococcus faecium, a leading antibiotic-resistant pathogen. By comparing isotopic enrichments of postinsertionally modified cell-wall precursors, we find that tripeptides and species without aspartic acid/asparagine (Asp/Asn, Asx) bridges are specific to mature cell wall. Additionally, we find that the sequence of cell-wall maturation varies throughout a cell cycle. We suggest that actively dividing E. faecium cells have three zones of unique peptidoglycan processing. Our results reveal new organizational characteristics of the bacterial cell wall that are important to understanding tertiary structure and designing novel drugs for antibiotic-resistant pathogens.

Characterization of structural variations in the peptidoglycan of vancomycin-susceptible Enterococcus faecium: understanding glycopeptide-antibiotic binding sites using mass spectrometry

Enterococcus faecium, an opportunistic pathogen that causes a significant number of hospital-acquired infections each year, presents a serious clinical challenge because an increasing number of infections are resistant to the so-called antibiotic of last resort, vancomycin. Vancomycin and other new glycopeptide derivatives target the bacterial cell wall, thereby perturbing its biosynthesis. To help determine the modes of action of glycopeptide antibiotics, we have developed a bottom-up mass spectrometry approach complemented by solid-state nuclear magnetic resonance (NMR) to elucidate important structural characteristics of vancomycin-susceptible E. faecium peptidoglycan. Using accurate-mass measurements and integrating ion-current chromatographic peaks of digested peptidoglycan, we identified individual muropeptide species and approximated the relative amount of each. Even though the organism investigated is susceptible to vancomycin, only 3% of the digested peptidoglycan has the well-known D-Ala-D-Ala vancomycin-binding site. The data are consistent with a previously proposed template model of cell-wall biosynthesis where D-Ala-D-Ala stems that are not cross-linked are cleaved in mature peptidoglycan. Additionally, our mass-spectrometry approach allowed differentiation and quantification of muropeptide species seen as unresolved chromatographic peaks. Our method provides an estimate of the extent of muropeptides containing O-acetylation, amidation, hydroxylation, and the number of species forming cyclic imides. The varieties of muropeptides on which the modifications are detected suggest that significant processing occurs in mature peptidoglycan where several enzymes are active in editing cell-wall structure.

Antibiotic resistance patterns of bacterial isolates from blood in San Francisco County, California, 1996-1999

Countywide antibiotic resistance patterns may provide additional information from that obtained from national sampling or individual hospitals. We reviewed susceptibility patterns of selected bacterial strains isolated from blood in San Francisco County from January 1996 to March 1999. We found substantial hospital-to-hospital variability in proportional resistance to antibiotics in multiple organisms. This variability was not correlated with hospital indices such as number of intensive care unit or total beds, annual admissions, or average length of stay. We also found a significant increase in methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and proportional resistance to multiple antipseudomonal antibiotics. We describe the utility, difficulties, and limitations of countywide surveillance.