Multidrug-resistant Gram-positive Organisms Research Articles

1192. Containment of Sustained Transmission of Drug-resistant Acinetobacter baumannii by Pulsed-Xenon Ultraviolet Disinfection of the Patient Room in the Intensive Care Unit

Abstract Background No-touch environmental disinfection has been highlighted in the last decade to control transmission of multidrug-resistant Gram-positive organisms including MRSA and VRE, but its effectiveness to control gram-negative bacteria has not been well examined. Also, its effectiveness outside the US healthcare setting is seldom reported. Methods This study was conducted in the intensive care unit (ICU) of Yamagata University Hospital, a 637-bed tertiary referral hospital. Sporadic acquisition of two drug-resistant Acinetobacter baumannii (2DRA) began in late 2013. Despite various infection control practices including hand hygiene promotion and intensified manual terminal cleaning, transmission of this pathogen continued. In February 2018, pulsed-xenon ultraviolet (PX-UV) disinfection was added. The study periods were defined as follows: the baseline period (August 2016 to January 2018, intensified manual cleaning) and the intervention period (February 2018 to December 2021, addition of PX-UV). Throughout the study periods, all patients were regularly screened for 2DRA to detect acquisition of those pathogens in the ICU. Results The incidence of newly acquired 2DRA significantly declined over time (4.45 per 1,000 patient days in the baseline period to 1.20 in the intervention period, relative risk (RR): 0.27, 95% confidence interval: 0.12-0.61). Notably, horizontal transmission of 2DRA was completely contained, not only in the ICU but also throughout the hospital (Figure). Newly acquired 2DRA events (all wards, monthly) Conclusion Adding PX-UV after through manual terminal cleaning is effective in controlling acquisition of 2DRA in the ICU patients and led to termination of transmission of 2DRA in our hospital. The effectiveness of PX-UV in controlling gram-negative MDROs in the non-US healthcare settings is suggested. Disclosures All Authors: No reported disclosures.

Linezolid Resistance Genes in Enterococci Isolated from Sediment and Zooplankton in Two Italian Coastal Areas.

Linezolid is a last-resort antibiotic for the treatment of severe infections caused by multidrug-resistant Gram-positive organisms; although linezolid resistance remains uncommon, the number of linezolid-resistant enterococci has increased in recent years due to worldwide spread of acquired resistance genes (cfr, optrA, and poxtA) in clinical, animal, and environmental settings. In this study, we investigated the occurrence of linezolid-resistant enterococci in marine samples from two coastal areas in Italy. Isolates grown on florfenicol-supplemented Slanetz-Bartley agar plates were investigated for their carriage of optrA, poxtA, and cfr genes; optrA was found in one Enterococcus faecalis isolate, poxtA was found in three Enterococcus faecium isolates and two Enterococcus hirae isolates, and cfr was not found. Two of the three poxtA-carrying E. faecium isolates and the two E. hirae isolates showed related pulsed-field gel electrophoresis (PFGE) profiles. Two E. faecium isolates belonged to the new sequence type 1710, which clustered in clonal complex 94, encompassing nosocomial strains. S1 PFGE/hybridization assays showed a double (chromosome and plasmid) location of poxtA and a plasmid location of optrA Whole-genome sequencing revealed that poxtA was contained in a Tn6657-like element carried by two plasmids (pEfm-EF3 and pEh-GE2) of similar size, found in different species, and that poxtA was flanked by two copies of IS1216 in both plasmids. In mating experiments, all but one strain (E. faecalis EN3) were able to transfer the poxtA gene to E. faecium 64/3. The occurrence of linezolid resistance genes in enterococci from marine samples is of great concern and highlights the need to improve practices aimed at limiting the transmission of linezolid-resistant strains to humans from environmental reservoirs.IMPORTANCE Linezolid is one of the few antimicrobials available to treat severe infections due to drug-resistant Gram-positive bacteria; therefore, the emergence of linezolid-resistant enterococci carrying transferable resistance determinants is of great concern for public health. Linezolid resistance genes (cfr, optrA, and poxtA), often plasmid located, can be transmitted via horizontal gene transfer and have the potential to spread globally. This study highlights the detection of enterococci carrying linezolid resistance genes from sediment and zooplankton samples from two coastal urban areas in Italy. The presence of clinically relevant resistant bacteria, such as linezolid-resistant enterococci, in marine environments could reflect their spillover from human and/or animal reservoirs and could indicate that coastal seawaters also might represent a source of these resistance genes.

Skin Colonizers and Catheter Associated Blood Stream Infections in Incident Indian Dialysis Patients.

Introduction:Skin colonization is a risk factor for multi-drug resistant (MDR) catheter-associated bloodstream infections (CABSI). This study aimed to determine the prevalence and spectrum of skin colonizing MDR organisms in incident HD patients and their correlation with CABSI.Methods:This single-center prospective cohort study included consecutive adult incident HD patients who underwent tunneled or non-tunneled internal jugular vein HD catheter insertion between June 1, 2017 and October 31, 2017. Nasal, axillary, and exit site swabs were obtained prior to catheter insertion, at 14–21 days, and 28–35 days after catheter insertion.Results:Forty-three patients (69.7% male, 32.5% diabetic) were included and provided baseline swabs, while 29 and 10 patients respectively were available for follow-up swabs. MDR bacterial colonization, MRSA colonization, and MDR gram-negative colonization on the baseline set of swabs were seen in 76.7%, 69.7%, and 9.3% patients respectively. Of the 29 patients with at least two consecutive sets of swabs, 79.3% showed persistent colonization by MDR gram-positive organisms, most commonly by MRSA. Six patients developed a CABSI during the follow-up period (incidence rate 3.7 per 1000 patient days), 83.4% were gram negative, and in only one instance (16.6%) was the bacterial strain identical to that which had previously colonized the skin.Conclusions:Three-fourths of HD patients were colonized by MDR bacteria prior to HD initiation. Despite the majority being persistently colonized by MDR gram-positive organisms, CABSIs were predominantly gram negative.

2287. Real-world Use of Tedizolid Phosphate: A Case Series of Long-Term Tolerability

BackgroundTedizolid is an oxazolidinone antibiotic with broad-spectrum Gram-positive activity approved for the treatment of skin and skin structure infections with a 6-day course. Oxazolidinone antibiotics represent appealing options for prolonged antimicrobial therapy due to their available oral formulations with excellent bioavailability and potent in vitro activity against various multidrug-resistant Gram-positive organisms, Mycobacterium spp., and Nocardia spp. Although tedizolid and linezolid offer a similar clinical spectrum based on antimicrobial activity alone, long-term use of linezolid is often limited by serious adverse effects. Preliminary assessments have suggested better tolerability with tedizolid; however, these are limited by shorter exposure duration. The objective of this study was to evaluate the long-term safety and tolerability of tedizolid.MethodsRetrospective cohort of adult patients receiving tedizolid for ≥ 28 days, with baseline complete blood cell (CBC) indices available, and CBC indices drawn ≥ 14 days into tedizolid course. The primary objective was to evaluate the long-term tolerability of tedizolid.Results13 patients met inclusion criteria: median age 61 years (IQR, 51–64 years), 69% male, 85% Caucasian. The majority of patients utilized tedizolid for suppression (85%), and the median duration of tedizolid was 113 days (IQR, 71–204 days). There were no differences in CBC indices when comparing baseline to last laboratory draw throughout tedizolid exposure: platelets (baseline: 203 x 109/L (IQR, 186–283 x 109/L) vs. last: 196 x 109/L (IQR, 161–303 x 109/L; p = 0.65), hemoglobin (baseline: 9.8 g/dL (IQR, 8.8–11.1 g/dL) vs. last: 11.7 g/dL (IQR, 11.0–13.1 g/dL; p = 0.10), and white blood cells (baseline: 6.2 x 109/L (IQR, 5.6–7.6 x 109/L) vs. last: 6.5 x 109/L (IQR, 6.3–7.3 x 109/L; p = 0.45). The final laboratory draws were obtained a median of 78 days (IQR, 44–119 days) into therapy. No patients experienced peripheral neuropathy, optic neuritis/visual changes, or serotonin syndrome during treatment/suppression with tedizolid during the period evaluated.ConclusionLong-term therapy with tedizolid appears to be well-tolerated. Treatment and suppression with tedizolid seems to be a safe alternative to linezolid.Disclosures All authors: No reported disclosures.

Dalbavancin and Oritavancin: An Innovative Approach to the Treatment of Gram-Positive Infections.

Health care-associated infections, especially those caused by multidrug-resistant gram-positive organisms, such as methicillin-resistant Staphylococcus aureus (MRSA), are a growing public health threat. In 2014, the U.S. Food and Drug Administration approved two new lipoglycopeptides, oritavancin and dalbavancin, for the treatment of acute bacterial skin and skin structure infections. The rationale for the development of these antimicrobials was partly to aid in the battle against vancomycin resistance in both Staphylococcus and Enterococcus. Considered a subclass of the glycopeptide antibiotics, the new lipoglycopeptides have similar mechanisms of action of binding to the carboxyl terminal d-alanyl-d-alanine residue of the growing peptide chains but differ from their parent glycopeptides by the addition of lipophilic tails. This addition allows for these agents to have prolonged half-lives, giving them unique dosing profiles. In addition, by concentrating at the site of action, they have increased potency against MRSA compared with vancomycin, the current mainstay of therapy. In this review, we focus on comparing and contrasting these two new agents with regard to their pharmacology, mechanisms of action, spectrum of activity, safety profiles, dosage and administration, and drug and laboratory interactions, and we review the clinical trials evaluating their use.

Prevention and Management of Extraventricular Drain-Related Ventriculitis

Ventriculitis after extraventricular drain (EVD) placement causes significant morbidity and mortality. This review is focused on the prevention and management of EVD-related ventriculitis. To prevent EVD-related ventriculitis, standardized EVD care, including sterile handling and strict infection control performances, and repeated education for healthcare workers are essential. Routine change of EVD is controversial. It can be considered when EVD is needed for more than 7 days. Perioperative antibiotic prophylaxis beyond 24 hours is not recommended, except for cerebrospinal fluid (CSF) leakage. Antibiotic-impregnated EVD catheter seems to reduce the incidence of EVD-related ventriculitis. CSF sampling for early detection of EVD-related ventriculitis can be considered 4 to 5 days after EVD insertion. Linezolid can be used for treating ventriculitis caused by multidrug-resistant Gram-positive organisms. Treatment options for extensively drug-resistant or pandrug resistant Gram-negative bacilli are scarce. Intraventricular colistin or aminoglycoside can be considered for those conditions. J Neurocrit Care 2014;7(2):97-103

Prevention and Management of Extraventricular Drain-Related Ventriculitis

Ventriculitis after extraventricular drain (EVD) placement causes significant morbidity and mortality. This review is focused on the prevention and management of EVD-related ventriculitis. To prevent EVD-related ventriculitis, standardized EVD care, including sterile handling and strict infection control performances, and repeated education for healthcare workers are essential. Routine change of EVD is controversial. It can be considered when EVD is needed for more than 7 days. Perioperative antibiotic prophylaxis beyond 24 hours is not recommended, except for cerebrospinal fluid (CSF) leakage. Antibiotic-impregnated EVD catheter seems to reduce the incidence of EVD-related ventriculitis. CSF sampling for early detection of EVD-related ventriculitis can be considered 4 to 5 days after EVD insertion. Linezolid can be used for treating ventriculitis caused by multidrug-resistant Gram-positive organisms. Treatment options for extensively drug-resistant or pandrug resistant Gram-negative bacilli are scarce. Intraventricular colistin or aminoglycoside can be considered for those conditions. Key Words: Cerebral ventriculitis; Ventriculostomy; Cerebrospinal fluid

Novel arylhydrazone derivatives bearing a rhodanine moiety: synthesis and evaluation of their antibacterial activities

A series of arylhydrazone derivatives bearing a rhodanine moiety have been synthesized, characterized, and evaluated as antibacterial agents. Some of these compounds showed potent antibacterial activities against several different strains of Gram-positive bacteria, including multidrug-resistant clinical isolates. Of the compounds tested, IIk and IIIk were identified as the most effective, with minimum inhibitory concentration values of 2-4 μg/mL against multidrug-resistant Gram-positive organisms, including methicillin-resistant and quinolone-resistant Staphylococcus aureus. None of the compounds exhibited any activity against the Gram-negative bacteria Escherichia coli 1356 at 64 μg/mL.

Synthesis and biological evaluation of rhodanine derivatives bearing a quinoline moiety as potent antimicrobial agents

Three series of rhodanine derivatives bearing a quinoline moiety (6a–h, 7a–g, and 8a–e) have been synthesized, characterized, and evaluated as antibacterial agents. The majority of these compounds showed potent antibacterial activities against several different strains of Gram-positive bacteria, including multidrug-resistant clinical isolates. Of the compounds tested, 6g and 8c were identified as the most effective with minimum inhibitory concentration (MIC) values of 1μg/mL against multidrug-resistant Gram-positive organisms, including methicillin-resistant and quinolone-resistant Staphylococcus aureus (MRSA and QRSA, respectively). None of the compounds exhibited any activity against the Gram-negative bacteria Escherichia coli 1356 at 64μg/mL. The cytotoxic activity assay showed that compounds 6g, 7g and 8e exhibited in vitro antibacterial activity at non-cytotoxic concentrations. Thus, these studies suggest that rhodanine derivatives bearing a quinoline moiety are interesting scaffolds for the development of novel Gram-positive antibacterial agents.

Thieno[2,3-d]pyrimidinedione derivatives as antibacterial agents

Several thieno[2,3-d]pyrimidinediones have been synthesized and examined for antibacterial activity against a range of Gram-positive and Gram-negative pathogens. Two compounds displayed potent activity (2–16 mg/L) against multi-drug resistant Gram-positive organisms, including methicillin resistant, vancomycin-intermediate, vancomycin-resistant Staphylococcus aureus (MRSA, VISA, VRSA) and vancomycin-resistant enterococci (VRE). Only one of these agents possessed moderate activity (16–32 mg/L) against Gram-negative strains. An examination of the cytotoxicity of these agents revealed that they displayed low toxicity (40–50 mg/L) against mammalian cells and very low hemolytic activity (2–7%). Taken together, these studies suggest that thieno[2,3-d]pyrimidinediones are interesting scaffolds for the development of novel Gram-positive antibacterial agents.

Present and Emerging Therapies for Methicillin-Resistant Staphylococcus aureus Skin and Soft Tissue Infections: Focus on Iclaprim

The management of skin and soft-tissue infections caused by multidrug resistant Gram-positive organisms, specifically methicillin-resistant Staphylococcus aureus (MRSA), continues to be a significant challenge for clinicians. Iclaprim is a diaminopyrimidine that has shown potent activity against various Gram-positive organisms, including MRSA, with limited Gram-negative activity similar to that of trimethoprim. Iclaprim has completed two Phase III trials with a submission of New Drug Application to the United States Food and Drug Administration (FDA) in 2008. Subsequently, a complete response letter not supporting the approval of iclaprim was released by the FDA. More recently, Acino Holding Ltd. has acquired the shares and data to iclaprim. Pending final draft guidance from the FDA for future studies, iclaprim may have a role in the management of skin and soft-tissue infections. A Medline search of articles through February 2011 and references of selected citations was conducted. Data from abstracts presented at the International Conference on Antimicrobial Agents and Chemotherapy and the Infectious Diseases Society of America annual meetings were also appraised. This article reviews the antimicrobial profile, pharmacokinetic and pharmacodynamic properties, and available clinical data of iclaprim.

Ceftaroline: A New Cephalosporin with Activity Against Resistant Gram‐Positive Pathogens

Ceftaroline is a novel, broad-spectrum, advanced-generation cephalosporin whose action is mediated by binding to penicillin-binding proteins in bacteria, consistent with other beta-lactam antibiotics. Ceftaroline is distinct in that it has antimicrobial activity against multidrug-resistant Staphylococcus aureus (including methicillin-resistant S. aureus, vancomycin-intermediate S. aureus [VISA], heteroresistant VISA, and vancomycin-resistant S. aureus), Streptococcus pneumonia (including drug-resistant strains), and respiratory gram-negative pathogens such as Moraxella catarrhalis and Haemophilus influenzae (including beta-lactamase-positive strains). Development of resistance to ceftaroline occurs rarely in gram-positive bacteria and at a similar rate to that of other oxyimino-cephalosporins in gram-negative bacteria. The inactive prodrug, ceftaroline fosamil, is administered by intravenous infusion and rapidly undergoes biotransformation to ceftaroline. Ceftaroline then follows a two-compartment pharmacokinetic model and is eliminated primarily by renal excretion, with a half-life of approximately 3 hours. Similar to other cephalosporins, time above the minimum inhibitory concentration is the pharmacodynamic parameter that best predicts efficacy for ceftaroline. Ceftaroline 600 mg intravenously every 12 hours has been shown to have similar efficacy to vancomycin plus aztreonam for the treatment of complicated skin and skin structure infections and to ceftriaxone for the treatment of community-acquired bacterial pneumonia in phase III clinical trials. Ceftaroline displayed a safety profile similar to that of other cephalosporins in clinical trials. Dosage adjustment is required for moderate renal impairment and for patients receiving hemodialysis. Ceftaroline breakpoints have been proposed but not confirmed. Ceftaroline is a renally excreted broad-spectrum cephalosporin that is clinically effective for the treatment of complicated skin and skin structure infections and community-acquired bacterial pneumonia, and it has distinctive activity against some difficult-to-treat multidrug-resistant gram-positive organisms.

Antimicrobial Resistance in Gram‐Negative Pathogens: Crafting the Tools Necessary to Navigate the Long Ascent out of the Abyss

The unrelenting rise in antimicrobial resistance is of great concern. The urgency of the problem is compounded by the recognition that fewer new antimicrobial agents are introduced each year [1]. Past efforts to curb resistance have been largely unsuccessful. It is important to note that what attention has been focused on emerging resistance, has been primarily directed toward gram-positive organisms (e.g., methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE)). Indeed, the few antimicrobial agents introduced in recent years have targeted treatment of multidrug resistant gram-positive organisms.

Optimizing Vancomycin Dosing through Pharmacodynamic Assessment Targeting Area under the Concentration-Time Curve/Minimum Inhibitory Concentration

Because of its activity against multidrug resistant gram-positive organisms, vancomycin is one of the antimicrobials most utilized in health care systems worldwide. Despite its widespread use, application of the pharmacodynamic principles governing vancomycin efficacy are not frequently considered in contemporary clinical practice. Although the vancomycin trough serum concentration has been used historically to assess the adequacy of a prescribed dose, data validating that this practice leads to improved patient outcomes do not exist. Alternatively, both in vitro and clinical outcomes data demonstrate improved results when an area under the concentration-time curve/minimum inhibitory concentration (AUC/MIC) of 400 mcg•h/mL or greater is achieved. This article describes the process through which individualized vancomycin dosing regimens targeting an AUC/MIC of 400 mcg•h/mL or greater, rather than trough serum concentration, at the beside can be derived. The equations, methodology, thought processes, benefits, potential pitfalls, and practical applicability of this method are specifically examined. Obtaining the actual MIC value—not an interpretation—from the microbiology laboratory and/or the MIC distribution for Staphylococcus aureus within one's own institution is essential for implementation of this method. Although vancomycin dosing recommendations suggested in contemporary practice guidelines are likely adequate for most patients, using the methods described here may lead to improved clinical outcomes for nonstandard conditions in patients who are critically ill and would benefit from an individualized dosing approach.

Antimicrobial susceptibility of Gram-positive bacteria isolated from European medical centres: results of the Daptomycin Surveillance Programme (2002–2004)

The antimicrobial susceptibility patterns of 9322 contemporary (2002-2004) gram-positive bacterial isolates collected from 31 medical centres in 14 countries in Europe were evaluated by broth microdilution methods according to CLSI guidelines. The isolates collected comprised Staphylococcus aureus (4842 isolates), coagulase-negative staphylococci (CoNS; 1942 isolates), Enterococcus faecalis (1147 isolates), Enterococcus faecium (391 isolates), beta-haemolytic streptococci (660 isolates) and viridans group streptococci (340 isolates). The organisms were tested against daptomycin and more than 20 comparator agents in Mueller-Hinton broth, supplemented with calcium to 50 mg/L when testing daptomycin. Overall, methicillin (oxacillin) resistance rates were 26.7% and 77.0% for S. aureus (MRSA) and CoNS, respectively, and the vancomycin resistance rate among enterococci was 6.1%. MRSA rates varied from 0.6% in Sweden to 40.2-43.0% in Belgium, Greece, Ireland, the UK and Israel, and VRE rates varied from 0% in Switzerland to 21.2% in Ireland. More than 99.9% of isolates tested were considered susceptible to daptomycin according to breakpoints established by the United States Food and Drug Administration and the CLSI. Daptomycin was active against all gram-positive species, with the highest MIC being 2, 8, 0.5 and 2 mg/L for staphylococci, enterococci, beta-haemolytic streptococci and viridans group streptococci, respectively. Daptomycin activity was not influenced adversely by resistance to other agents among staphylococci or enterococci. This novel lipopeptide (daptomycin) appears to be an excellent alternative therapeutic option for serious infections caused by multidrug-resistant gram-positive organisms isolated in Europe.

Pharmacokinetics of Daptomycin in a Critically Ill Adolescent with Vancomycin-Resistant Enterococcal Endocarditis

Daptomycin is a lipopeptide antibiotic active against multidrug-resistant gram-positive organisms. Our search of the literature found no published pediatric pharmacokinetic data. We report the use of pharmacokinetic analysis of daptomycin in a 13-year-old boy with vancomycin-resistant Enterococcus faecium endocarditis. Pharamcokinetic parameters were found to be significantly different from published adult parameters, such as a faster elimination rate, shorter half-life, and increased clearance. These age-related differences in the pharmacokinetic profile of daptomycin have significant dosing implications. As the use of this drug for off-label indications and in pediatric populations increases, it is important for clinicians to better understand the drug's pharmacokinetic profile in these patient populations.

In vitro activities of daptomycin, vancomycin, linezolid, and quinupristin-dalfopristin against Staphylococci and Enterococci, including vancomycin- intermediate and -resistant strains.

The in vitro activity of daptomycin was compared with those of vancomycin, linezolid, and quinupristin-dalfopristin against a variety (n = 203) of gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and S. epidermidis (MRSA and MRSE, respectively), vancomycin-resistant enterococci (VRE), and vancomycin-intermediate S. aureus (VISA). Overall, daptomycin was more active against all organisms tested, except Enterococcus faecium and VISA, against which its activity was similar to that of quinupristin-dalfopristin. In time-kill studies with MRSA, MRSE, VRE, and VISA, daptomycin demonstrated greater bactericidal activity than all other drugs tested, killing > or =3 log CFU/ml by 8 h. Daptomycin may be a potential alternative drug therapy for multidrug-resistant gram-positive organisms and warrants further investigation.

Gram-positive resistance: challenge for the development of new antibiotics.

The incidence of infections caused by multidrug-resistant Gram-positive organisms is increasing despite advances in antibacterial therapy over the last 20 years. As the pathogens causing these infections are frequently resistant to most currently available antibacterials, they are extremely difficult to treat. Problematic pathogens include strains of Streptococcus pneumoniae resistant to beta-lactams and macrolides, viridans group streptococci resistant to beta-lactams and aminoglycosides, enterococci resistant to vancomycin and teicoplanin and highly resistant to penicillins and aminoglycosides, and Staphylococcus aureus resistant to methicillin, other beta-lactams, macrolides, lincosamides and aminoglycosides. Other important pathogens include Streptococcus pyogenes resistant to macrolides (and suspected to be resistant to penicillin), macrolide-resistant streptococci of groups B, C, and G, coagulase-negative staphylococci resistant to beta-lactams, aminoglycosides, macrolides, lincosamides and glycopeptides, multiresistant strains of Listeria and Corynebacterium and Gram-positive anaerobes, such as Peptostreptococcus and Clostridium, resistant to penicillins and macrolides. Thus, there is an urgent need for new antibacterial agents that are able to overcome multidrug-resistant mechanisms. The novel semisynthetic injectable streptogramin quinupristin/dalfopristin offers the prospect of effective treatment against many of the above pathogens.