Multisite Detection of Tn1549-Mediated vanB Vancomycin Resistance in Multidrug-Resistant Enterococcus faecalis ST6 in Texas and Florida.

In the United States, vanB-mediated resistance in enterococci is rare. We characterized three sequence type (ST) 6, vancomycin-resistant Enterococcus faecalis isolates causing bacteremia in unique patients in spatiotemporally distinct settings. Isolates were recovered between 2018 and 2020 in two cities in the United States (Houston, TX; Miami, FL). The isolates harbored the vanB operon on a chromosomally located Tn1549 transposon, and epidemiological data suggested multiple introductions of the vanB gene cluster into ST6 E. faecalis.

Contemporary Clinical and Molecular Epidemiology of Vancomycin-Resistant Enterococcal Bacteremia: A Prospective Multicenter Cohort Study (VENOUS I).

BACKGROUND: Vancomycin-resistant enterococci (VRE) are major therapeutic challenges. Prospective contemporary data characterizing the clinical and molecular epidemiology of VRE bloodstream infections (BSIs) are lacking. METHODS: The Vancomycin-Resistant Enterococcal BSI Outcomes Study (VENOUS I) is a prospective observational cohort of adult patients with enterococcal BSI in 11 US hospitals. We included patients with Enterococcus faecalis or Enterococcus faecium BSI with ≥1 follow-up blood culture(s) within 7 days and availability of isolate(s) for further characterization. The primary study outcome was in-hospital mortality. Secondary outcomes were mortality at days 4, 7, 10, 12, and 15 after index blood culture. A desirability of outcome ranking was constructed to assess the association of vancomycin resistance with outcomes. All index isolates were subjected to whole genome sequencing. RESULTS: Forty-two of 232 (18%) patients died in hospital and 39 (17%) exhibited microbiological failure (lack of clearance in the first 4 days). Neutropenia (hazard ratio [HR], 3.13), microbiological failure (HR, 2.4), VRE BSI (HR, 2.13), use of urinary catheter (HR, 1.85), and Pitt BSI score ≥2 (HR, 1.83) were significant predictors of in-hospital mortality. Microbiological failure was the strongest predictor of in-hospital mortality in patients with E faecium bacteremia (HR, 5.03). The impact of vancomycin resistance on mortality in our cohort changed throughout the course of hospitalization. Enterococcus faecalis sequence type 6 was a predominant multidrug-resistant lineage, whereas a heterogeneous genomic population of E faecium was identified. CONCLUSIONS: Failure of early eradication of VRE from the bloodstream is a major factor associated with poor outcomes.

Pharmacodynamics of daptomycin in combination with other antibiotics for the treatment of enterococcal bacteraemia.

Daptomycin is commonly prescribed in combination with other antibiotics for treatment of enterococcal bacteraemia. Whilst a free drug area under the concentration-time curve to minimum inhibitory concentration (fAUC/MIC) ratio >27.4 is associated with 30-day survival with daptomycin monotherapy, it is unknown whether receipt of other antibiotics affects this threshold. Data were pooled from seven published trials assessing outcomes in daptomycin-treated enterococcal bacteraemia, including patients receiving daptomycin (≥72 h) and any ß-lactam, intravenous aminoglycoside, linezolid, tigecycline and/or vancomycin. Exposures were calculated using a published population pharmacokinetic model based on creatinine clearance, 90% protein binding and daptomycin Etest MIC. The fAUC/MIC threshold predictive of 30-day survival was determined by classification and regression tree analysis. Following pooling of data, 240 adults were included; 137 (57.1%) were alive at 30 days. A majority of patients were immunosuppressed (65.8%) and received a ß-lactam (94.6%). Examining the threshold in low-acuity patients (n = 135) to control for co-morbidities, these patients were more likely to survive when fAUC/MIC >12.3 was achieved (63.2% vs. 20.0%; P = 0.015). The difference remained significant in a multivariable logistic regression model that controlled for infection source and immunosuppression (P = 0.017). This threshold is 2-fold lower than that observed with daptomycin monotherapy. Probabilities of threshold attainment using a 10 mg/kg/day dose were 100% for isolates with MICs ≤ 2 mg/L and 95.2% for a 12 mg/kg/day dose for MICs of 4 mg/L. These data support the use of high-dose daptomycin in combination with another antibiotic for treatment of enterococcal bacteraemia.

Novel Strategies for the Management of Vancomycin-Resistant Enterococcal Infections.

PURPOSE OF REVIEW: Vancomycin-resistant enterococci (VRE) are important nosocomial pathogens that commonly affect critically ill patients. VRE have a remarkable genetic plasticity allowing them to acquire genes associated with antimicrobial resistance. Therefore, the treatment of deep-seated infections due to VRE has become a challenge for the clinician. The purpose of this review is to assess the current and future strategies for the management of recalcitrant deep-seated VRE infections and efforts for infection control in the hospital setting. RECENT FINDINGS: Preventing colonization and decolonization of multidrug-resistant bacteria are becoming the most promising novel strategies to control and eradicate VRE from the hospital environment. Fecal microbiota transplantation (FMT) has shown remarkable results on treating colonization and infection due to Clostridiodes difficille and VRE, as well as to recover the integrity of the gut microbiota under antibiotic pressure. Initial reports have shown the efficacy of FMT on reestablishing patient microbiota diversity in the gut and reducing the dominance of VRE in the gastrointestinal tract. In addition, the use of bacteriophages may be a promising strategy in eradicating VRE from the gut of patients. Until these strategies become widely available in the hospital setting, the implementation of infection control measures and stewardship programs are paramount for the control of this pathogen and each program should provide recommendations for the proper use of antibiotics and develop strategies that help to detect populations at risk of VRE colonization, prevent and control nosocomial transmission of VRE, and develop educational programs for all healthcare workers addressing the epidemiology of VRE and the potential impact of these pathogens on the cost and outcomes of patients. In terms of antibiotic strategies, daptomycin has become the standard of care for the management of deep-seated infections due to VRE. However, recent evidence indicates that the efficacy of this antibiotic is limited, and higher (10-12 mg/kg) doses and/or combination with ß-lactams is needed for therapeutic success. Clinical data to support the best use of daptomycin against VRE are urgently needed. This review provides an overview of recent developments regarding the prevention, treatment, control, and eradication of VRE in the hospital setting. We aim to provide an update of the most recent therapeutic strategies to treat deep-seated infections due to VRE.

Pharmacodynamic Analysis of Daptomycin-treated Enterococcal Bacteremia: It Is Time to Change the Breakpoint.

BACKGROUND: Currently, there is debate over whether the daptomycin susceptibility breakpoint for enterococci (ie, minimum inhibitory concentration [MIC] ≤4 mg/L) is appropriate. In bacteremia, observational data support prescription of high doses (>8 mg/kg). However, pharmacodynamic targets associated with positive patient outcomes are undefined. METHODS: Data were pooled from observational studies that assessed outcomes in daptomycin-treated enterococcal bacteremia. Patients who received an additional antienterococcal antibiotic and/or a ß-lactam antibiotic at any time during treatment were excluded. Daptomycin exposures were calculated using a published population pharmacokinetic model. The free drug area under the concentration-time curve to MIC ratio (fAUC/MIC) threshold predictive of survival at 30 days was identified by classification and regression tree analysis and confirmed with multivariable logistic regression. Monte Carlo simulations determined the probability of target attainment (PTA) at clinically relevant MICs. RESULTS: Of 114 patients who received daptomycin monotherapy, 67 (58.8%) were alive at 30 days. A fAUC/MIC >27.43 was associated with survival in low-acuity (n = 77) patients (68.9 vs 37.5%, P = .006), which remained significant after adjusting for infection source and immunosuppression (P = .026). The PTA for a 6-mg/kg/day (every 24 hours) dose was 1.5%-5.5% when the MIC was 4 mg/L (ie, daptomycin-susceptible) and 91.0%-97.9% when the MIC was 1 mg/L. CONCLUSIONS: For enterococcal bacteremia, a daptomycin fAUC/MIC >27.43 was associated with 30-day survival among low-acuity patients. As pharmacodynamics for the approved dose are optimized only when MIC ≤1 mg/L, these data continue to stress the importance of reevaluation of the susceptibility breakpoint.

Plasma Interferon-Gamma-Inducible Protein 10 Level Associates With Abnormal Memory B Cells Phenotypes in Perinatal HIV Infection.

We demonstrate for perinatally HIV-infected children and adolescents receiving combined antiretroviral therapy and in good clinical status with respect to HIV disease that high concentrations of interferon-gamma-inducible protein 10 associate with increased exhausted memory B cells.

Incidence and predictors of antiretroviral resistance in perinatally HIV-1 infected children and adolescents.

OBJECTIVES: Individuals with perinatally acquired HIV infection have benefited from antiretroviral therapy. However, they often have complex patterns of major resistance mutations that limit the effectiveness of available antiretroviral medications. Knowledge of incidence rates of major antiretroviral resistance mutations should provide a benchmark enabling comparisons of different HIV care delivery modalities. METHODS: We test the hypothesis that incidence rate of major antiretroviral resistance mutations will decline with improvement in HIV care between 1998 and 2009 to NRTI, NNRTI, PI and triple class resistance in perinatally HIV infected individuals. Logistic regression is used to evaluate predictors of single and triple class resistance. RESULTS: Sixty-six individuals are included from a total population of 97 perinatally HIV infected individuals. The incidence rate of NRTI, NNRTI, PI and triple class resistance decreases with decreasing age in parallel with the introduction of new HIV treatment regimens. The youngest children (born 2000-2007) are free of triple class resistance. Mono-therapy associates with major resistance mutations to NRTI (OR 8.7, CI 1.5-50.9, P 0.02); NNRTI exposure associates with major resistance mutations to NNRTI (OR 24.4, CI 5.7-104.5, P 0.01) and triple class resistance (OR 10.7, CI 1.8-67.1, P 0.01). Cumulative viral load is an important predictor of PI resistance (OR 4.0, CI 1.3-12.3, P 0.02). CONCLUSIONS: There is a progressive decrease in the incidence rate of major resistance mutations to antiretroviral drugs and triple class resistance from the oldest to the youngest birth cohort; where adolescents have the highest risk of harboring resistant viruses. The incidence rate of major antiretroviral resistance mutations provides a benchmark for the comparative measurement of effectiveness of different HIV care delivery modalities.

Prevalence and risk factors associated with resistance-associated mutations to etravirine in a cohort of perinatally HIV-infected children.

BACKGROUND: Etravirine is a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with reduced cross-resistance to first-generation NNRTIs. Because many perinatally HIV-infected patients have been treated with first-generation NNRTIs, they may have acquired resistance-associated mutations to etravirine (RAMe). METHODS: We determined for the interval 1998-2009 the prevalence and factors associated with the presence of RAMe. RESULTS: Twenty-three of 66 (34.8%) children had RAMe; the most common were 181C (19.6%), 190A (7.5%), 98G (6%), 106I (4.5%), 179D (4.5%), 100I (3%), 181I (1.5%), 138A (1.5%) and 179T (1.5%). Eleven children with RAMe (17%) had a mutation score between 2.5 and 3.5 and 1 (1.5%) a score ≥4, indicating an intermediate and reduced response to etravirine. For each 1% increase in CD4% there is a 7% decrease in the odds of RAMe (OR 0.93; 95% CI 0.88-0.97; P < 0.01). History of nevirapine use (OR 8.95; 95% CI 2.31-34.73; P < 0.01) and Hispanic ethnicity (OR 4.76; 95% CI 1.03-21.87; P = 0.04) are significantly associated with risk of RAMe. CONCLUSIONS: RAMe are present and common among antiretroviral-experienced perinatally HIV-infected children without previous exposure to etravirine. This could limit the efficacy of etravirine-based regimens. In addition, our results underscore the importance of taking previous history of nevirapine into account for combined antiretroviral therapy regimens that contain etravirine.

Empyema necessitans and acute osteomyelitis associated with community acquired methicillin resistant Staphylococcus aureus in an infant

Staphylococcus aureus es uno de los principales patógenos a nivel mundial. Durante los útimos años se ha reportado un incremento en el número de casos de S. aureus resistente a la meticilina adquiridos en la comunidad, tanto en niños como en adultos de los Estados Unidos y de otras partes del mundo. En el presente trabajo reportamos un caso de empiema necessitans y osteomielitis aguda en un niño de 19 meses de edad previamente sano. El presente reporte resalta la cambiante epidemiología de S. aureus tanto en la comunidad como en el medio hospitalario y la importancia de establecer guías apropiadas para el diagnóstico, el tratamiento y la vigilancia de este relevante problema de salud pública.

Staphylococcus aureus is a well recognized pathogen with global distribution. In recent years community-associated, methicillin-resistant S. aureus has emerged as an increasing cause of severe infections among adults and children. Herein, a case is reported of a previously healthy, 19-month-old male, who presented with empyema necessitans and acute osteomyelitis due to a community-associated, methicillin-resistant, S. aureus strain. This report highlights the evolving epidemiology of S. aureus, as important pathogen in the community as well as the hospital setting, and the importance of establishing appropriate guidelines for diagnosis, management and surveillance of this public health problem.

Dissemination of methicillin-resistant Staphylococcus aureus USA300 sequence type 8 lineage in Latin America.

BACKGROUND: Methicillin-resistant Staphylococus aureus (MRSA) is an important nosocomial and community-associated (CA) pathogen. Recently, a variant of the MRSA USA300 clone emerged and disseminated in South America, causing important clinical problems. METHODS: S. aureus isolates were prospectively collected (2006-2008) from 32 tertiary hospitals in Colombia, Ecuador, Peru, and Venezuela. MRSA isolates were subjected to antimicrobial susceptibility testing and pulsed-field gel electrophoresis and were categorized as health care-associated (HA)-like or CA-like clones on the basis of genotypic characteristics and detection of genes encoding Panton-Valentine leukocidin and staphylococcal cassette chromosome (SCC) mec IV. In addition, multilocus sequence typing of representative isolates of each major CA-MRSA pulsotype was performed, and the presence of USA300-associated toxins and the arcA gene was investigated for all isolates categorized as CA-MRSA. RESULTS: A total of 1570 S. aureus were included; 651 were MRSA (41%)--with the highest rate of MRSA isolation in Peru (62%) and the lowest in Venezuela (26%)--and 71%, 27%, and 2% were classified as HA-like, CA-like, and non-CA/HA-like clones, respectively. Only 9 MRSA isolates were confirmed to have reduced susceptibility to glycopeptides (glycopeptide-intermediate S. aureus phenotype). The most common pulsotype (designated ComA) among the CA-like MRSA strains was found in 96% of isolates, with the majority (81%) having a < or =6-band difference with the USA300-0114 strain. Representative isolates of this clone were sequence type 8; however, unlike the USA300-0114 strain, they harbored a different SCCmec IV subtype and lacked arcA (an indicator of the arginine catabolic mobile element). CONCLUSION: A variant CA-MRSA USA300 clone has become established in South America and, in some countries, is endemic in hospital settings.

Empyema necessitans and acute osteomyelitis associated with community-acquired methicillin-resistant Staphylococcus aureus in an infant.

Staphylococcus aureus is a well recognized pathogen with global distribution. In recent years community-associated, methicillin-resistant S. aureus has emerged as an increasing cause of severe infections among adults and children. Herein, a case is reported of a previously healthy, 19-month-old male, who presented with empyema necessitans and acute osteomyelitis due to a community-associated, methicillin-resistant, S. aureus strain. This report highlights the evolving epidemiology of S. aureus, as important pathogen in the community as well as the hospital setting, and the importance of establishing appropriate guidelines for diagnosis, management and surveillance of this public health problem.