Management of infections caused by vancomycin-resistant gram-positive bacteria

Telavancin: a novel semisynthetic lipoglycopeptide agent to counter the challenge of resistant Gram-positive pathogens

Telavancin (TD-6424), a semisynthetic lipoglycopeptide vancomycin-derivative, is a novel antimicrobial agent developed by Theravance for overcoming resistant Gram-positive bacterial infections, specifically methicillin-resistant Staphylococcus aureus (MRSA). The US Food and Drug Administration (USFDA) had approved telavancin in 2009 for the treatment of complicated skin and skin structure infections (cSSSIs) caused by Gram-positive bacteria, including MRSA (S. aureus, Streptococcus agalactiae, Streptococcus pyogenes, Streptococcus anginosus group, or Enterococcus faecalis). Telavancin has two proposed mechanisms of action. In vitro, telavancin has a rapid, concentration-dependent bactericidal effect, due to disruption of cell membrane integrity. Telavancin has demonstrable in vitro activity against aerobic and anaerobic Gram-positive bacteria. Telavancin and vancomycin have similar spectra of activity. Gram-negative bacteria are usually non-susceptible to telavancin. Telavancin has been successfully tested in various animal models of bacteremia, endocarditis, meningitis, and pneumonia. Phase II Telavancin versus Standard Therapy for Treatment of Complicated Skin and Soft-Tissue Infections due to Gram-Positive Bacteria (FAST 1 and FAST 2) and phase III [Assessment of Telavancin in Complicated Skin and Skin Structure Infections 1 (ATLAS 1 and ATLAS 2)] clinical trials have been conducted for evaluating telavancin's efficacy and safety in cSSSIs. Phase III clinical trials have been carried out for evaluating telavancin's safety and efficacy in nosocomial pneumonia [Assessment of Telavancin for Treatment of Hospital acquired Pneumonia 1 and 2 (ATTAIN 1 and ATTAIN 2)]. A phase II randomized, double-blind, clinical trial has been carried out for evaluating telavancin's safety and efficacy in uncomplicated S. aureus bacteremia [Telavancin for Treatment of Uncomplicated S. aureus Bacteremia (ASSURE)]. Pacemaker lead-related infective endocarditis due to a vancomycin intermediate S. aureus (VISA) strain (non-daptomycin susceptible) was successfully treated with parenteral telavancin for 8 weeks. Telavancin extensively binds to serum albumin (~93%) and has a relatively small volume of distribution. Telavancin is not biotransformed by any cytochrome P450 microsomal enzymes and excreted mainly in the urine. Though well-tolerated, worrisome adverse effects, including renal dysfunction and QTc prolongation are of potential concern. Given its extensive binding to plasma proteins, long half-life, and a long post-antibiotic effect, it represents a promising addition to the therapeutic armamentarium in combating infections caused by resistant Gram-positive pathogens, namely, MRSA.

Rising Vancomycin-Resistant Enterococcus Infections in Hospitalized Children in the United States

OBJECTIVE

Vancomycin-resistant Enterococcus (VRE) is an emerging drug-resistant organism responsible for increasing numbers of nosocomial infections in adults. Few data are available on the epidemiology and impact of VRE infections in children. We hypothesized a significant increase in VRE infections among hospitalized children. Additionally, we predicted that VRE infection would be associated with certain comorbid conditions and increased duration and cost of hospitalization.

METHODS

A retrospective study of inpatient pediatric patients was performed using data on hospitalizations for VRE from the Healthcare Cost and Utilization Project Kids' Inpatient Database from 1997 to 2012. We used a multivariable logistic regression model to establish factors associated with VRE infection and a high-dimensional propensity score match to evaluate death, length of stay, and cost of hospitalization.

RESULTS

Hospitalizations for VRE infection showed an increasing trend, from 53 hospitalizations per million in 1997 to 120 in 2012 (P < .001). Conditions associated with VRE included Clostridium difficile infection and other diagnoses involving immunosuppression and significant antibiotic and health care exposure. Patients with VRE infection had a significantly longer length of stay (attributable difference [AD] 2.1 days, P < .001) and higher hospitalization costs (AD $8233, P = .004). VRE infection was not associated with an increased risk of death (odds ratio 1.03; 95% confidence interval 0.73-1.47).

CONCLUSIONS

VRE infections among hospitalized children are increasing at a substantial rate. This study demonstrates the significant impact of VRE on the health of pediatric patients and highlights the importance of strict adherence to existing infection control policies and VRE surveillance in certain high-risk pediatric populations.

Distribution of drug-resistant bacteria and rational use of clinical antimicrobial agents

Open wound may lead to infection in patients. Due to overuse of medication, certain bacteria have become resistant to drugs currently available. The aim of the present study was to provide a guide to ameliorate the appropriate and rational use of clinical antimicrobial agents by analyzing the distribution of drug-resistant pathogenic bacteria in patients. Between October 2013 and January 2015, 126 patients were selected at the Department of Orthopedics. Wound secretion samples were collected, and the pathogen bacteria isolated and identified. Identification was performed using an automated identification instrument and the Kirby-Bauer antibiotic method was used to evaluate the bacterial resistance. Of the 126 patients, 118 patients were infected (infection rate, 93.65%). Additionally, 47 strains of gram-positive pathogenic bacteria (39.83%) and 71 strains of pathogenic-gram negative bacteria (60.17%) were identified. The bacteria were most likely to be resistant to penicillin while sensitive to vancomycin and imipenem. Some bacteria were resistant to several antibacterial agents. The results showed that existing risk factors at the Department of Orthopedics were complex and any non-standard procedures were able to cause bacterial infection. There were obvious dissimilarities among infectious bacteria with regard to their sensitivity to various antibacterial agents. Manipulation techniques during the treatment process were performed in a sterile manner and the use of antibacterial agents was required to be strictly in accordance with the results of drug sensitivity tests to provide effective etiologic information and a treatment plan for clinical trials and to reduce the risk of infection by multi-resistant bacteria.

Feasibility, efficacy, and adverse effects of outpatient antibacterial prophylaxis in children with acute myeloid leukemia

BACKGROUND

Intensive chemotherapy for pediatric acute myeloid leukemia incurs the risk of infectious complications, but the benefits of antibiotic prophylaxis remain unclear.

METHODS

In the current study, among 103 children treated on the AML02 protocol between October 2002 and October 2008 at St. Jude Children's Research Hospital, the authors retrospectively assessed the effect of antibiotic prophylaxis on the frequency of febrile neutropenia, clinically or microbiologically confirmed infections (including bacteremia), and antibiotic resistance, as well as on the results of nasal and rectal surveillance cultures. Initially, patients received no prophylaxis or oral cephalosporin (group A). The protocol was then amended to administer intravenous cefepime alone or intravenous vancomycin plus either oral cephalosporin, oral ciprofloxacin, or intravenous cefepime (group B).

RESULTS

There were 334 infectious episodes. Patients in group A had a significantly greater frequency of documented infections and bacteremia (both P < .0001) (including gram-positive and gram-negative bacteremia; P = .0003 and .001, respectively) compared with patients in group B, especially viridans streptococcal bacteremia (P = .001). The incidence of febrile neutropenia without documented infection was not found to be different between the 2 groups. Five cases of bacteremia with vancomycin-resistant enterococci (VRE) occurred in group B (vs none in group A), without related mortality. Two of these cases were preceded by positive VRE rectal surveillance cultures.

CONCLUSIONS

Outpatient intravenous antibiotic prophylaxis is feasible in children with acute myeloid leukemia and reduces the frequency of documented infection but not of febrile neutropenia. Despite the emergence of VRE bacteremia, the benefits favor antibiotic prophylaxis. Creative approaches to shorten the duration of prophylaxis and thereby minimize resistance should be explored.

Vancomycin-resistant Enterococcus outbreak in a neonatal intensive care unit: epidemiology, molecular analysis and risk factors

BACKGROUND

Vancomycin-resistant Enterococcus faecium (VRE) may cause outbreaks in neonatal intensive care units (NICU). We describe a biphasic VRE outbreak and identify risk factors for VRE acquisition.

METHODS

After the occurrence of 2 cases of VRE infections in a 44-bed NICU, a bundle of interventions was implemented that included active surveillance cultures for VRE, enhanced infection control measures, and audits on antimicrobial use, from June to December 2008. Analysis was performed using polymerase chain reaction and pulse-field gel electrophoresis techniques. A case-control study was conducted to identify risk factors.

RESULTS

Among 253 neonates screened, 101 (39.9%) were found to be colonized with VRE. During the first 9 weeks of the study period, 59 new cases were detected. Molecular analysis showed 1 predominant clone. During weeks 10-12, no new cases of VRE colonization were detected; however, at week 13, just when the outbreak appeared to be over, a second wave occurred, with 42 new cases and multiple clones detected. Multivariate analysis identified administration of antimicrobial therapy for late-onset neonatal sepsis and hospitalization during the first month of this outbreak as significant risk factors for VRE colonization.

CONCLUSION

Both a high prevalence of VRE colonization and antimicrobial use promoted the transmission of VRE during this biphasic outbreak. Adherence to infection control measures and antimicrobial stewardship policies are of utmost importance.

Polyclonal outbreak of vancomycin-resistant Enterococcus faecium in a pediatric oncology department

We present a polyclonal outbreak of vancomycin-resistant enterococci (VRE) colonization in a pediatric oncology department and the role of a bundle of actions. After the occurrence of VRE bloodstream infections in 2 patients, an active surveillance of VRE colonization was started. Enhanced infection control measures and closure of the department to new admissions for the first 3 months were implemented. Among 32 patients screened for VRE, 21 were found colonized. Daily prevalence of VRE colonization among hospitalized patients ranged from 40% to 75%, but no new VRE infections occurred. Monthly incidence of VRE colonization decreased from 2.5 to 0.6 cases per 100 occupied bed-days at the end of this outbreak by the implementation of the above-mentioned measures. All VRE isolates tested were Enterococcus faecium carrying VanA gene. Pulsed field gel electrophoresis showed a polyclonal outbreak. A case-control study did not show any particular risk factors for colonization. High use of glycopeptide was noted before study outbreak that was drastically decreased during the study but only temporarily. Control of VRE in pediatric oncology departments with high colonization rates is challenging and requires a multifaceted strategy. Polyclonal spread of VRE found in this study suggests a possible effect of prior antimicrobial overuse and the critical need for antimicrobial stewardship especially in the era of multidrug-resistant bacteria.