Clinical practice guidelines by the infectious diseases society of america for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children

Validation and development of population pharmacokinetic model of vancomycin using a real-world database from a nationwide free web application

INTRODUCTION

Vancomycin requires a population pharmacokinetic (popPK) model to estimate the area under the concentration-time curve (AUC), and an AUC-guided dosing strategy is necessary. This study aimed to develop a popPK model for vancomycin using a real-world database pooled from a nationwide web application (PAT).

METHODS

In this retrospective study, the PAT database between December 14, 2022 and April 6, 2023 was used to develop a popPK model. The model was validated and compared with six existing models based on the predictive performance of datasets from another PAT database and the Kumamoto University Hospital. The developed model determined the dosing strategy for achieving the target AUC.

RESULTS

The modeling populations consisted of 7146 (13,372 concentrations from the PAT database), 3805 (7540 concentrations from the PAT database), and 783 (1775 concentrations from Kumamoto University Hospital) individuals. A two-compartment popPK model was developed that incorporated creatinine clearance as a covariate for clearance and body weight for central and peripheral volumes of distribution. The validation demonstrated that the popPK model exhibited the smallest mean absolute prediction error of 5.07, outperforming others (ranging from 5.10 to 5.83). The dosing strategies suggested a first dose of 30 mg/kg and maintenance doses adjusted for kidney function and age.

CONCLUSIONS

This study demonstrated the updating of PAT through the validation and development of a popPK model using a vast amount of data collected from anonymous PAT users.

Effect of a bundle intervention on adherence to quality-of-care indicators and on clinical outcomes in patients with Staphylococcus aureus bacteraemia hospitalized in non-referral community hospitals

BACKGROUND

Although a significant number of cases of Staphylococcus aureus bacteraemia (SAB) are managed at non-referral community hospitals, the impact of a bundle-of-care intervention in this setting has not yet been explored.

METHODS

We performed a quasi-experimental before-after study with the implementation of a bundle of care for the management of SAB at five non-referral community hospitals and a tertiary care university hospital. Structured recommendations for the five indicators selected to assess quality of care were provided to investigators before the implementation of the bundle and monthly thereafter. Primary endpoints were adherence to the bundle intervention and treatment failure, defined as death or relapse at 90 days of follow-up.

RESULTS

One hundred and seventy patients were included in the pre-intervention period and 103 in the intervention period. Patient characteristics were similar in both periods. Multivariate analysis controlling for potential confounders showed that performance of echocardiography was the only factor associated with improved adherence to the bundle in the intervention period (adjusted OR 2.13; 95% CI 1.13-4.02). Adherence to the bundle, performance of follow-up blood cultures, and adequate duration of antibiotic therapy for complicated SAB presented non-significant improvements. The intervention was not associated with a lower rate of 90 day treatment failure (OR 1.11; 95% CI 0.70-1.77).

CONCLUSIONS

A bundle-of-care intervention for the management of SAB at non-referral community hospitals increased adherence to quality indicators, but did not significantly reduce rates of 90 day mortality or relapse.

The Utilization of Echocardiography in Children With Staphylococcus aureus Bacteremia

The need for echocardiography in pediatric Staphylococcus aureus bacteremia (SAB) remains uncertain. We reviewed 331 pediatric SAB cases. Nine subjects, all with comorbidities, met the echocardiogram criteria for infective endocarditis (IE). IE was associated with congenital heart disease and prolonged bacteremia, suggesting that echocardiography is unnecessary in most children with SAB.

Heartfelt Impact: A Descriptive Analysis of Ceftaroline-Containing Regimens in Endocarditis due to Methicillin-Resistant Staphylococcus aureus

INTRODUCTION

Infective endocarditis (IE) due to methicillin-resistant Staphylococcus aureus (MRSA) is characterized by frequent treatment failure to first-line agents and high mortality, necessitating use of alternative management strategies. Ceftaroline fosamil (CPT) is a cephalosporin antibiotic with activity against MRSA but without regulatory approval for the indication of IE. This study describes clinical experience with CPT-based regimens utilized in MRSA-IE.

METHODS

This is a retrospective, observational, descriptive analysis of patients from two major urban medical centers in Detroit, Michigan from 2011 to 2023. Included adult patients (≥ 18 years) had ≥ 1 positive blood culture for MRSA, met definitive clinical criteria for IE, and received CPT for ≥ 72 h. The primary outcome was treatment failure, defined as a composite of 30-day all-cause mortality from index culture or failure to improve or resolve infectious signs/symptoms after CPT initiation.

RESULTS

Seventy patients were included. The median (interquartile range [IQR]) age was 51 (34-63) years and 45.7% were male. Persons with injection drug use (PWID) made up 55.7% of the cohort and right-sided IE was the most prevalent subtype (50.0%). CPT was frequently employed second-line or later, often in combination with vancomycin (10.0%) or daptomycin (72.9%). Overall, 31.4% experienced treatment failure and 30-day all-cause mortality occurred in 15.7%.

CONCLUSIONS

These findings illustrate the challenges posed by MRSA-IE, including frequent treatment failures, and highlight the utilization of CPT as salvage therapy. Comparative studies are needed to more clearly define its role in MRSA-IE.

Retrospective study to investigate appropriate duration of antibiotic treatment for uncomplicated Staphylococcus aureus bacteremia in patients with immunodeficiency

BACKGROUND

Since the appropriate antibiotic duration for uncomplicated Staphylococcus aureus (S. aureus) bacteremia (u-SAB) in an immunocompromised state is still unclear, physicians are likely to extend antibiotic therapy from 2 weeks to 4-6 weeks. To examine the appropriate duration of antibiotic therapy for u-SAB, we performed this study.

PATIENTS AND METHODS

We reviewed all patients with u-SAB at our institute seen between January 2020 and August 2023. A total of 51 patients were enrolled, and they were divided into the following two groups by antibiotic duration: longer duration group ≥28 days after blood culture negativity, and shorter duration group. Then, the patients were matched by a propensity score using the covariates of age, sex, qSOFA, and CCI. The primary outcome was to identify the prognosis by duration of antibiotic treatment.

RESULTS

After propensity score matching, all-cause 30-day mortality was 0 % in both groups. Hence, there was no significant difference in all-cause 90 days mortality (19.0% vs 9.5%, p = 0.33) or recurrence (9.5%% vs 0%, p = 0.22). Before propensity-score matching, we found that a serum level of CRP 2.0 mg/dL and greater after intravenous antibiotic treatment was one of the poor prognostic factors. The cut-off value of serum CRP level was 2.0 mg/dL with a sensitivity of 82.1% and a specificity of 75.0%.

CONCLUSION

We suggested that 4-6 weeks of antibiotic treatment for immunodeficient u-SAB patients was unnecessary. Moreover, the serum level of CRP after completion of IV antibiotic treatment could be a prognostic marker for u-SAB.

Evaluation of pharmacokinetic target attainment and hematological toxicity of linezolid in pediatric patients

BACKGROUND

Linezolid is commonly used to treat severe and/or resistant Gram-positive infections. Few studies have assessed its pharmacokinetic (PK) target attainment in pediatrics.

OBJECTIVE

To evaluate the percentage of pediatrics achieving the PK targets of linezolid with standard dosing regimens and to assess the incidence and risk factors associated with its hematologic toxicity.

METHODS

This prospective observational study included pediatric patients aged 0-14 who received linezolid for suspected or proven Gram-positive infections. Linezolid trough concentrations and the 24-h area under the curve (AUC24) were estimated, and hematologic toxicity was assessed.

RESULTS

Seventeen pediatric patients (5 neonates and 12 older pediatrics) were included. A wide variability was observed in linezolid's trough and AUC24 (ranging from 0.5 to 14.4 mg/L and from 86 to 700 mg.h/L, respectively). The median AUC24 was significantly higher in neonates than older pediatrics (436 [350-574] vs. 200 [134-272] mg,h/L, P = 0.01). Out of all patients, only 41% achieved adequate drug exposure (AUC24 160-300 mg.h/L and trough 2-7 mg/L), with 24% having subtherapeutic, and 35% having higher-than-optimal exposures. Hematological toxicity was observed in 53% of cases. Identified risk factors include treatment duration over 7 days, baseline platelet counts below 150 × 109/L, sepsis/septic shock, and concomitant use of meropenem.

CONCLUSIONS

Linezolid's standard dosing failed to achieve its PK targets in approximately half of our pediatric cohort. Our findings highlight the complex interplay between the risk factors of linezolid-associated hematological toxicity and underscore the importance of its vigilant use and monitoring, particularly in pediatrics with concomitant multiple risk factors.

Inhibitory effect of Bacillus velezensis 1273 strain cell-free supernatant against developing and preformed biofilms of Staphylococcus aureus and MRSA

Microbial biofilms constitute a significant virulence factor and a substantial challenge in clinical environments due to their role in promoting antimicrobial resistance and their resilience to eradication efforts. Methicillin-resistant Staphylococcus aureus (MRSA) infections substantially increase healthcare costs, extend hospitalizations, and elevate morbidity and mortality rates. Therefore, developing innovative strategies to target and eliminate these bacteria and their biofilms effectively is imperative for robust epidemiological control. In this study, we evaluated the antibacterial and antibiofilm activities of cell-free supernatant (CFS) obtained from the Bacillus velezensis 1273 strain culture. Our data showed that CFS inhibited the growth of S. aureus ATCC 29213 and MRSA (clinical strain), with greater efficacy observed against S. aureus (1:16 dilution). Furthermore, CFS showed substantial potential in reducing biofilm formation in both strains (∼30 %) at subinhibitory concentrations. Additionally, the antibacterial activity against biofilm-formed cells showed that pure CFS treatment decreased the viability of S. aureus (60 %) and MRSA (45 %) sessile cells. We further demonstrated that CFS treatment induces the production of reactive oxygen species (ROS) and damages the membranes and cell walls of the pathogen cells. Genome analysis revealed the presence of genes encoding bacteriocins and secondary metabolites with antibacterial activity in the B. velezensis 1273 genome. These findings highlight the potential of probiotic bacterial metabolites as antibiofilm and anti-multidrug-resistant pathogens.

Impact of rapid blood culture identification PCR panel on optimal antibiotic use in methicillin-susceptible Staphylococcus aureus bacteremia

Rapid identification of methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia may optimize antibiotic use and clinical outcomes. The study objective was to assess the impact of the BioFire® blood culture identification (BCID) polymerase chain reaction (PCR) panel on antibiotic use and clinical outcomes in patients with MSSA bacteremia. This was a retrospective chart review of adult inpatients with MSSA bacteremia during the pre-PCR (June 2018-December 2019) and post-PCR (June 2020-December 2021) implementation periods. The primary endpoint was the difference between the pre-PCR and post-PCR groups in time to optimal MSSA antibiotic therapy (oxacillin or cefazolin). Secondary endpoints included duration of anti-MRSA antibiotic use, in-hospital mortality, hospital and ICU lengths of stay, duration of bacteremia, and 30-day MSSA-related and all-cause readmissions. Two hundred patients were included in the study (100 per group). Median time to optimal therapy was reduced by 19.9 hours in the post-PCR group (49 vs 29.1 hours, respectively, P < 0.001). PCR implementation was associated with significant reductions in the initiation of empiric anti-MRSA antibiotic therapy (98% vs 84%, P = 0.001), duration of empiric anti-MRSA antibiotic use (44.2 vs 20.9 hours, P < 0.001), and duration of bacteremia (68.6 vs 47.3 hours, P = 0.015). No significant differences in length of stay, in-hospital mortality, or 30-day MSSA-related or all-cause readmissions were observed. In patients with MSSA bacteremia, BCID PCR panel implementation decreased time to optimal MSSA antibiotic therapy, duration of bacteremia, and duration of empiric anti-MRSA antibiotic therapy.

IMPORTANCE

In this retrospective study of 200 patients with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia, the implementation of the BioFire® blood culture identification polymerase chain reaction (PCR) panel was associated with a decreased time to optimal MSSA antibiotic therapy and shorter durations of empiric anti-MRSA antibiotic therapy and bacteremia. The findings demonstrate the significant role of rapid PCR testing and routine stewardship review in optimizing antimicrobial therapy and management of MSSA bacteremia.

Identification of Patients Who Require Two-Point Blood Sampling for the Peak and Trough Values Rather Than One-Point Blood Sampling for the Trough Value for the Evaluation of AUC of Vancomycin Using Bayesian Estimation

OBJECTIVES

It is recommended to adjust the dose of vancomycin (VCM) with a target area under the concentration-time curve (AUC) of 400-600 μg·h/mL. Factors that affect the deviation between AUCs are estimated from the trough value alone and the trough and peak values using practical AUC-guided therapeutic drug monitoring (PAT) for vancomycin. In this study, factors that affect AUC were evaluated.

METHODS

AUCs were estimated from a single trough value and trough and peak values, and the patients were classified into those who showed a 10% or greater deviation (deviation group) and those in whom the deviation was less than 10% (no-deviation group). Risk factors related to ≥ 10% deviation of AUC were identified by univariate and multivariate analysis.

RESULTS

As a result of univariate and multivariate analysis of 30 patients in the deviation group and 344 patients in the no-deviation group, a creatinine clearance (CLcr) of ≥ 110 mL/min (odds ratio (OR) = 3.697, 95% confidence interval (CI) = 1.616-8.457, p = 0.002), heart failure with a brain natriuretic peptide (BNP) of ≥ 300 pg/mL (OR = 4.854, 95%CI = 1.199-19.656, p = 0.027), and the concomitant use of angiotensin converting enzyme inhibitor or angiotensin II receptor blocker (ACE-I/ARB) (OR = 2.544, 95%CI = 1.074-6.024, p = 0.034) were identified as risk factors of ≥ 10% deviation of AUC.

CONCLUSIONS

Estimation of AUC by two-point blood sampling for the trough and peak values rather than one-point blood sampling for the trough value is suggested to improve the prediction accuracy in patients with enhanced renal function, severe heart failure, and patients using ACE-I/ARB.

Bioequivalence Analysis of Clindamycin Hydrochloride Capsules in Healthy Chinese Subjects Under Fasted and Fed Conditions

Clindamycin is a lincosamide antibiotic for the treatment of staphylococcal, streptococcal, and anaerobic bacterial infections. We conducted a single-center, single-dose, 2-preparation, 2-period, 2-sequence, randomized, open-label, 2 × 2 crossover study to evaluate the pharmacokinetics (PKs) and safety of the test and reference clindamycin hydrochloride capsules in healthy Chinese subjects under both fasted and fed conditions. Forty-eight subjects were enrolled in the study totally, with 24 subjects in each group. All subjects were asked to take a test or reference preparation, under either fasted or fed condition, and their blood samples were collected and assayed by a validated high-performance liquid chromatography-tandem mass spectrometry method. PK parameters including maximum plasma concentration, area under the plasma concentration-time curve from time 0 to the last concentration, and area under the plasma concentration-time curve from time 0 to infinity were estimated with noncompartmental model and analyzed. Results showed that the PK profiles of the 2 preparations were consistent and met the bioequivalence criteria. Food was identified as a factor that had an impact on clindamycin absorption. The safety of clindamycin hydrochloride capsules was satisfactory. This study proved that the 2 clindamycin hydrochloride capsules were bioequivalent in healthy Chinese subjects under both fasted and fed conditions.

Early Oral Antibiotic Switch in Staphylococcus aureus Bacteraemia: The Staphylococcus aureus Network Adaptive Platform (SNAP) Trial Early Oral Switch Protocol

BACKGROUND

Staphylococcus aureus bloodstream infection (bacteremia) is traditionally treated with at least 2 weeks of intravenous (IV) antibiotics in adults, 3-7 days in children, and often longer for those with complicated disease. The current practice of treating S. aureus bacteremia (SAB) with prolonged IV antibiotics (rather than oral antibiotics) is based on historical observational research and expert opinion. Prolonged IV antibiotic therapy has significant disadvantages for patients and healthcare systems, and there is growing interest in whether a switch to oral antibiotics following an initial period of IV therapy is a safe alternative for clinically stable patients.

PROTOCOL

The early oral switch (EOS) domain of the S. aureus Network Adaptive Platform (SNAP) trial will assess early switch to oral antibiotics compared with continued IV treatment in clinically stable patients with SAB. The primary endpoint is 90-day all-cause mortality. Hospitalised SAB patients are assessed at platform day 7 ±2 (uncomplicated SAB) and day 14 ±2 (complicated SAB) to determine their eligibility for randomization to EOS (intervention) or continued IV treatment (current standard of care).

DISCUSSION

Recruitment is occurring in the EOS domain of the SNAP trial. As of August 2023, 21% of all SNAP participants had been randomized to the EOS domain, a total of 264 participants across 77 centers, with an aim to recruit at least 1000 participants. We describe challenges and facilitators to enrolment in this domain to aid those planning similar trials.

Duration of antimicrobial treatment for uncomplicated streptococcal bacteraemia: Another example of shorter is better

OBJECTIVES

Duration of treatment for uncomplicated streptococcal bacteraemia is unknown. The study aims to assess clinical outcomes of patients with uncomplicated streptococcal bacteraemia receiving a short course (5-10 days) of antimicrobial treatment compared to those receiving the traditional, longer duration (11-18 days).

METHODS

This retrospective study was conducted at the Lausanne University Hospital, Switzerland and included episodes of uncomplicated streptococcal bacteraemia among adult patients from 2015 to 2023. Clinical failure was defined as mortality, recurrence of bacteraemia by the same streptococcal species and development in bone and joint infection within 120 days.

RESULTS

During the study period, 336 episodes of uncomplicated streptococcal bacteraemia were included. The median duration of antimicrobial treatment was 10 days (interquartile range: 7-14); 184 (55%) and 152 (45%) episodes received a short (5-10 days) and long (11-18 days) duration of antimicrobial treatment, respectively. Forty-three (13%) episodes had clinical failure; 120-day mortality was 11% (36 episodes); recurrence of bacteraemia by the same streptococcal species was observed in 8 episodes (2%). No difference in clinical failure was observed between episodes receiving short and long courses of antimicrobial treatment (10% versus 16%; P 0.143). The Cox multivariable regression model found that a Charlson comorbidity index >4 (aHR 4.87, 95% CI 3.08-7.71), and septic shock (1.67, 1.04-2.67) were associated with clinical failure; a short course of antimicrobial treatment was not associated with clinical failure (0.90, 0.57-1.12).

CONCLUSIONS

This study has shown that a short duration of antimicrobial treatment for cases of streptococcal bacteraemia is effective and safe.

Effect of low vs. high vancomycin trough level on the clinical outcomes of adult patients with sepsis or gram-positive bacterial infections: a systematic review and meta-analysis

BACKGROUND & OBJECTIVE

The Infectious Disease Society of America guidelines recommend vancomycin trough levels of 15-20 mg/L for severe methicillin-resistant Staphylococcus aureus. However, recent consensus guidelines of four infectious disease organizations no longer recommend vancomycin dosing using minimum serum trough concentrations. Therefore, this study aimed to evaluate the impact of low (< 15 mg/L) vs. high (≥ 15 mg/L) vancomycin trough levels on clinical outcomes in adult patients with sepsis or gram-positive bacterial infections.

METHOD

A systematic literature review from inception to December 2022 was conducted using four online databases, followed by a meta-analysis. The outcomes of interest included clinical response/efficacy, microbial clearance, length of ICU stay, treatment failure, nephrotoxicity, and mortality.

RESULTS

Fourteen cohort studies met the inclusion criteria from which vancomycin trough concentration data were available for 5,228 participants. Our analysis found no association between vancomycin trough levels and clinical response [OR = 1.06 (95%CI 0.41-2.72], p = 0.91], microbial clearance [OR = 0.47 (95% CI 0.23-0.96), p = 0.04], ICU length of stay [MD=-1.01 (95%CI -5.73-3.71), p = 0.68], or nephrotoxicity [OR = 0.57 (95% CI 0.31-1.06), p = 0.07]. However, low trough levels were associated with a non-significant trend towards a lower risk of treatment failure [OR = 0.89 (95% CI 0.73-1.10), p = 0.28] and were significantly associated with reduced risk of all-cause mortality [OR = 0.74 (95% CI 0.62-0.90), p = 0.002].

CONCLUSION

Except for a lower risk of treatment failure and all-cause mortality at low vancomycin trough levels, this meta-analysis found no significant association between vancomycin trough levels and clinical outcomes in adult patients with sepsis or gram-positive bacterial infections.

Persistent bloodstream infection in children: examining the role for repeat blood cultures

Repeat blood cultures are common in children after an initial positive culture. However, in contrast to adults, there are little data to help guide clinicians when a repeat culture is necessary to assess for persistent bacteremia. This study identifies factors associated with persistent bloodstream infections (BSI) in children to inform diagnostic stewardship. This cross-sectional study of children less than 18 years with at least one positive blood culture over a 5-year period utilized a generalized linear equation model to predict patient and microbial factors associated with persistent BSI defined as a positive blood culture with the same organism >48 hours after the index culture. Four hundred and five patients had 502 positive blood cultures yielding 556 organisms. Sixty-seven (13.2%) cultures were persistently positive. Anaerobic organisms (0/37) and Streptococcus species (0/104) were never recovered from repeat cultures. Staphylococcus aureus (OR 9.45, CI 5.15-17.35) and yeast (OR 78.18, CI 9.45-646.6) were statistically associated with persistent BSI. Patients with prior positive cultures (OR 1.44, CI 1.12-1.84) or a central venous catheter (OR 2.20, 95% CI 1.04-3.92) were also at risk for persistence. Immune dysfunction and elevated inflammatory markers at the time of the index blood culture were not significantly associated with persistence. Yeast or S. aureus were associated with persistent BSI, while anaerobes and Streptococcus species were never persistent. Patient characteristics at the time of blood draw did not predict persistence other than having previous positive blood cultures or a central venous catheter. These data can inform when repeat blood cultures have clinical value and reduce the risk of unnecessary blood draws in children.

IMPORTANCE

We identify factors associated with bloodstream infection persistence in children. Our findings can help guide blood culture stewardship efforts in pediatric patients, especially in light of blood culture supply shortages.

Long versus short course anti-microbial therapy of uncomplicated Staphylococcus aureus bacteraemia: a systematic review

BACKGROUND

Current guidelines recommend at least 2 weeks duration of antibiotic therapy (DOT) for patients with uncomplicated Staphylococcus aureus bacteraemia (SAB) but the evidence for this recommendation is unclear.

OBJECTIVES

To perform a systematic literature review assessing current evidence for recommended DOT for patients with SAB.

METHODS

The following are the methods used for this study.

DATA SOURCES

We searched MEDLINE, ISI Web of Science, the Cochrane Database and clinicaltrials.gov from inception to March 30, 2024. References of eligible studies were screened and experts in the field contacted for additional articles.

STUDY ELIGIBILITY CRITERIA

All clinical studies, regardless of design, publication status and language.

PARTICIPANTS

Adult patients with uncomplicated SAB.

INTERVENTIONS

Long (>14 days; >18 days; 11-16 days) vs. short (≤14 days; 10-18 days; 6-10 days, respectively) DOT with the DOT being defined as the first until the last day of antibiotic therapy.

ASSESSMENT OF RISK OF BIAS

Risk of bias was assessed using the ROBINS-I-tool.

METHODS OF DATA SYNTHESIS

The primary outcome was 90-day all-cause mortality. Only studies presenting results of adjusted analyses for mortality were included. Data synthesis could not be performed.

RESULTS

Eleven nonrandomized studies were identified that fulfilled the pre-defined inclusion criteria, of which three studies reported adjusted effect ratios. Only these were included in the final analysis. We did not find any RCT. Two studies with 1230 patients reported the primary endpoint 90-day all-cause mortality. Neither found a statistically significant superiority for longer (>14 days; 11-16 days) or shorter DOT (≤14 days; 6-10 days, respectively) for patients with uncomplicated SAB. Two studies investigated the secondary endpoint 30-day all-cause mortality (>18 days; 11-16 days vs. 10-18 days; 6-10 days, respectively) and did not find a statistically significant difference. All included studies had a moderate risk of bias.

CONCLUSIONS

Sound evidence that supports any duration of antibiotic treatment for patients with uncomplicated SAB is lacking.

Impact of physical build on serum vancomycin concentrations of patients undergoing hemodialysis: A retrospective cohort study at an acute care hospital

INTRODUCTION

Estimating the serum vancomycin (VCM) concentrations of lean and patients with obesity is challenging. Additionally, VCM dosing for Japanese patients undergoing hemodialysis remains particularly unclear. This study aimed to determine the impact of the physical build on serum VCM concentrations of Japanese patients undergoing hemodialysis.

METHODS

This retrospective cohort study included hospitalized patients undergoing hemodialysis, who received treatment with VCM between May 1, 2019, and December 31, 2021, at Kansai Rosai Hospital, which is a 642-bed acute care hospital in Japan. Patients were divided into the following three groups based on their body mass index (BMI): lean group (≤18.5 kg/m2), normal group (18.5-25 kg/m2), and obese group (≥25 kg/m2). The VCM dose and predialysis serum VCM concentration (PVC) were compared.

RESULTS

This study included 191 patients. There were 50 patients in the lean group, 85 in the normal group, and 56 in the obese group. The median loading doses per body weight were 24.0, 22.1, and 21.2 mg/kg for the lean, normal, and obese groups, respectively. The VCM dose per body weight decreased significantly with increasing BMI. The median PVCs of the lean and normal groups were approximately 15 mg/L (not significantly different). However, the median PVC of the obese group was 18.3 mg/L, which was significantly higher (P < 0.001).

CONCLUSIONS

The VCM dose per body weight for Japanese patients undergoing hemodialysis should be adjusted based on the BMI.

Measuring the Direct Medical Costs of Hospital-Onset Infections Using an Analogy Costing Framework

BACKGROUND

The majority of recent estimates on the direct medical cost attributable to hospital-onset infections (HOIs) has focused on device- or procedure-associated HOIs. The attributable costs of HOIs that are not associated with device use or procedures have not been extensively studied.

OBJECTIVE

We developed simulation models of attributable cost for 16 HOIs and estimated the total direct medical cost, including nondevice-related HOIs in the USA for 2011 and 2015.

DATA AND METHODS

We used total discharge costs associated with HOI-related hospitalization from the National Inpatient Sample and applied an analogy costing methodology to develop simulation models of the costs attributable to HOIs. The mean attributable cost estimate from the simulation analysis was then multiplied by previously published estimates of the number of HOIs for 2011 and 2015 to generate national estimates of direct medical costs.

RESULTS

After adjusting all estimates to 2017 US dollars, attributable cost estimates for select nondevice-related infections attributable cost estimates ranged from $7661 for ear, eye, nose, throat, and mouth (EENTM) infections to $27,709 for cardiovascular system infections in 2011; and from $8394 for EENTM to $26,445 for central nervous system infections in 2016 (based on 2015 incidence data). The national direct medical costs for all HOIs were $14.6 billion in 2011 and $12.1 billion in 2016. Nondevice- and nonprocedure-associated HOIs comprise approximately 26-28% of total HOI costs.

CONCLUSION

Results suggest that nondevice- and nonprocedure-related HOIs result in considerable costs to the healthcare system.

Impact of [18F] FDG PET/CT on outcomes in patients with Staphylococcus aureus bacteremia: A retrospective single-center experience

OBJECTIVE

Staphylococcus aureus bacteremia (SAB) is a leading cause of community and hospital-acquired bacteremia with significant morbidity and mortality. Effective management depends on accurate diagnosis, source control and assessment of metastatic infections. [18F] FDG PET/CT has been shown to reduce mortality in high-risk SAB patients. This study aims to evaluate the impact of [18F] FDG PET/CT on outcomes in patients with SAB.

METHODS

Single-center, retrospective, real-life setting study including all consecutive SAB cases from 2017 to 2019. Medical records were analyzed to collect information.

RESULTS

Out of the 315 included patients, 132 underwent [18F] FDG PET/CT. In those patients, a clear focus of infection was more frequently identified, leading to better adapted treatments and extended hospital stays. Overall mortality rates at 30 days, 90 days and one year were 25.1 %, 36.8 % and 44.8 % respectively. Mortality was significantly lower in the [18F] FDG PET/CT group (p < 0.0001) and persisted (p < 0.05) after adjusting for imbalances between groups regarding oncologic patients and deaths within 7 days. The difference in mortality remained significant irrespective of prolonged bacteremia but was not significant with regard to hospital-acquired SAB. Supplementary analysis using the Cox proportional hazards model confirmed that [18F] FDG PET/CT was significantly associated with reduced mortality (p < 0.05).

CONCLUSION

In this real-life cohort, patients with SAB having undergone [18F] FDG PET/CT experienced lower mortality rates, highlighting the additional value of [18F] FDG PET/CT in SAB management. Further research is needed to identify the subpopulations that would benefit most from the integration of [18F] FDG PET/CT in their work-up.

Risk factors for positive follow-up blood cultures in critically ill adults with Gram-negative bacteraemia

Objectives

To evaluate the utility of follow-up blood cultures (FUBCs) for Gram-negative bloodstream infection (BSI) in ICU patients and identify risk factors for repeat positive cultures.

Methods

This was a single-centre, retrospective cohort study of critically ill adults with Gram-negative BSI between 1 January 2015 and 1 January 2020. Critically ill patients with one or more blood cultures positive for a Gram-negative organism were included. Descriptive and inferential statistics were performed with an alpha of 0.05.

Results

A total of 148 critically ill patients with Gram-negative BSI were included, with 42 patients (28.4%) having one or more positive FUBCs. The majority (66.2%) were admitted to a medical ICU. The most common organisms isolated were Escherichia coli (n = 56, 37.8%) and Klebsiella pneumoniae (n = 26, 17.6%). Significant patient risk factors associated with a positive FUBC on univariate regression included: MDR organisms, immunocompromised status, fever, vasopressor use at time of FUBC, lack of source control attainment, and higher quick Pitt bacteraemia score. Multivariable penalized logistic regression indicated that lack of source control containment and less time from index to FUBC remained significantly associated with repeat positive FUBC.

Conclusions

This is the first study to investigate the use of FUBC for Gram-negative BSI in exclusively ICU patients. Risk factors for repeat positive FUBC in this population include lack of source control and less time between index and FUBC. Prospective studies are needed to fully elucidate the role of FUBCs in critically ill patients with Gram-negative BSI.

Evaluating the duration of antimicrobial therapy for the treatment of orthopedic hardware infections

The optimal duration of antimicrobial therapy for orthopedic hardware infections is unclear. We identified 216 patients with orthopedic hardware infections, of whom 42 (19%) later had relapsed infection. Chronic suppressive antimicrobial therapy beyond 12 weeks was not significantly associated with lower odds of relapse.IMPORTANCEThere is debate about how long to continue antibiotics after initial treatment of bone and joint infections when hardware remains in place. This study found no benefit from continuing antibiotics longer than 12 weeks when trying to prevent recurrent infection.

Consequences of the COVID-19 Pandemic on the Incidence, Management and Outcomes of Staphylococcus aureus Bacteraemia: Experience in a Spanish Hospital

This work aims to assess the impact of the COVID-19 pandemic on the mortality and incidence of complications in patients with bacteraemia due to Staphylococcus aureus (BSA). All episodes of BSA at the Costa del Sol University Hospital (Marbella, Spain) were recorded during the acute phase of the COVID-19 pandemic (March 2020-March 2022) and compared with those in a previous period (February 2018-February 2020). Demographic, clinical and prognostic variables were recorded. The outcomes were measured as 14- and 30-day mortality and the incidence of complications/death. Mortality during the pandemic was 28.7% at 14 days and 35% at 30 days, while in the pre-pandemic group, it was 18.9% and 23.3%, respectively. For overall complications/deaths, the incidence rate was higher in the pandemic group, with 42.7%. No significant differences were observed between groups. Seventeen patients with COVID-19 were identified, with mortality rates of 64.7% and 70.6% at 14 and 30 days. Multivariate analysis established the presence of sepsis at diagnosis as a predictor of mortality, but not BSA, during the pandemic phase. In conclusion, BSA is a disease with high mortality, which was slightly higher during the pandemic phase. No differences were found in adherence to the bundle in our centre.

Distinct Clinical Endpoints of Staphylococcus aureus Bacteraemia Complicate Assessment of Outcome

BACKGROUND

We aimed to test the hypothesis that development of metastatic infection represents a distinct clinical endpoint from death due to Staphylococcus aureus bacteremia (SAB).

METHODS

We conducted a retrospective observational study of adults with SAB between 20 December 2019 and 23 August st2022 (n = 464). Simple logistic regression, odds ratios, and z-scores were used to compare host, clinical, and microbiologic features.

RESULTS

Co-occurrence of attributable mortality and metastatic infection was infrequent. Charlson Comorbidity Index and age were strongly associated with attributable mortality, but not metastatic infection. We compared patients with fatal SAB (without clinically-apparent metastatic complications, 14.4% of cohort), metastatic SAB (without attributable mortality, 22.2%), neither complication (56.7%), and overlapping fatal/metastatic SAB (6.7%). Compared to SAB without complications, fatal SAB was specifically associated with older age and multi-morbidity. Metastatic SAB was specifically associated with community acquisition, persistent fever, persistent bacteremia, and recurrence. Endocarditis was over-represented in the fatal/metastatic SAB overlap group, which shared patient characteristics with fatal SAB. In contrast to other (predominantly musculoskeletal) metastatic complications, endocarditis was associated with increased mortality, with death occurring in older multi-morbid patients later after SAB onset.

CONCLUSIONS

Patients with SAB experience distinct clinical endpoints: (i) early death, associated with multi-morbidity and age; (ii) metastatic (predominantly musculoskeletal) SAB; (iii) endocarditis, associated with late death occurring in older people with multi-morbidity, and (iv) bacteraemia without complications. These distinctions could be important for selecting appropriate outcomes in clinical trials: different interventions might be required to reduce mortality versus improve clinical response in patients with metastatic SAB.

Staphylococcus capitis: insights into epidemiology, virulence, and antimicrobial resistance of a clinically relevant bacterial species

SUMMARYStaphylococcus capitis is divided into two subspecies, S. capitis subsp. ureolyticus (renamed urealyticus in 1992; ATCC 49326) and S. capitis subsp. capitis (ATCC 27840), and fits with the archetype of clinically relevant coagulase-negative staphylococci (CoNS). S. capitis is a commensal bacterium of the skin in humans, which must be considered an opportunistic pathogen of interest particularly as soon as it is identified in a clinically relevant specimen from an immunocompromised patient. Several studies have highlighted the potential determinants underlying S. capitis pathogenicity, resistance profiles, and virulence factors. In addition, mobile genetic element acquisitions and mutations contribute to S. capitis genome adaptation to its environment. Over the past decades, antibiotic resistance has been identified for S. capitis in almost all the families of the currently available antibiotics and is related to the emergence of multidrug-resistant clones of high clinical significance. The present review summarizes the current knowledge concerning the taxonomic position of S. capitis among staphylococci, the involvement of this species in human colonization and diseases, the virulence factors supporting its pathogenicity, and the phenotypic and genomic antimicrobial resistance profiles of this species.

Methicillin resistant Staphylococcus aureus mazEF expression promotes infections by influencing cellular growth, antibiotic sensitivity, and formation of biofilms

Staphylococcus aureus infections are hard to treat due to the emergence of antibiotic resistant strains, as well as their ability to form biofilms. The MazEF toxin-antitoxin system is thought play a role in bacterial biofilm phenotype as well as antibiotic resistance. In S. aureus, the physiologic function of the mazEF gene in the disease transition from acute to chronic infection is not well understood. In methicillin resistant S. aureus (MRSA), loss of mazF expression results in loss of resistance to first generation cephalosporins. mazF::tn displayed sensitivity while the isogenic wild type (WT) remained resistant. mazF::tn displayed significantly increased growth of biofilms on metal implants over 48 h compared to WT and the complemented transposon mutant. mazF::tn biofilms displayed significantly decreased antibiotic tolerance to vancomycin and cefazolin in comparison to WT and complement biofilms. Mice given mazF::tn in a sepsis model displayed less abscess burden and increased survival (100%) when treated with cefazolin compared to WT bacteremia treated with cefazolin (20%). mazF::tn periprosthetic joint infections displayed increased biofilm burden at acute time points and decreased biofilm burden at chronic time points. Our data suggests MazEF in MRSA is responsible for controlling growth of biofilms, antibiotic tolerance, and influence chronic infections in vivo.

An evaluation of the empirical vancomycin dosing guide in pediatric cardiology

BACKGROUND

Higher doses of vancomycin are currently prescribed due to the emergence of bacterial tolerance and resistance. This study aimed to evaluate the efficacy and safety of the currently adopted vancomycin dosing guide in pediatric cardiology.

METHODS

This was a single-center prospective cohort study with pediatric cardiac patients, younger than 14 years, from June 2020 to March 2021. The patients received intravenous vancomycin (40 mg/kg/day divided every 6-8 h) according to the department's vancomycin medication administration guide (MAG) for at least three days.

RESULTS

In total, 88 cardiac patients were included, with a median age of 0.82 years (IQR: 0.25-2.9), and 51 (58%) received cardiopulmonary bypass surgery (CPB). The majority (71.6%, n = 61) achieved a serum vancomycin level within the therapeutic range (7-20 mg/L). Infants, young children, and children exposed to CPB surgery had an increased incidence of subtherapeutic vancomycin levels, [7 (29.2%); P = 0.033], [13 (54.2%); P = 0.01], and [21 (87.5%); P = 0.009] respectively. After the treatment, 8 (10%) patients had an elevated Serum creatinine (SCr) and 2 (2.5%) developed acute kidney injury (AKI). However, no significant difference was found between the patients developing AKI or an elevated SCr and the group who did not, in terms of clinical, therapeutic, and demographic characteristics, except for the decreased incidence of SCr elevation in patients receiving an ACE inhibitor, [4 (36.4%); P = 0.036].

CONCLUSION

Our institution followed MAG recommendations; however, subtherapeutic serum concentrations were evident in infants, young children, and CPB patients. Strategies to prevent AKI should be investigated, as the possible causes have not been identified in this study.

Comparative effectiveness and safety of six antibiotics in treating MRSA infections: A network meta-analysis

OBJECTIVES

This study conducted a network meta-analysis comparing linezolid, teicoplanin, daptomycin, tigecycline, and ceftaroline fosamil with vancomycin for treating MRSA-related diseases, addressing the lack of comprehensive evaluations in existing research on antibiotic therapy for MRSA infections.

METHODS

We systematically searched databases including PubMed, Embase, Web of Science, the Cochrane Librar up to August 22, 2023. All eligible randomized controlled trials of the six antibiotics were included in the NMA, and their effectiveness and safety were compared across various MRSA-related diseases. Categorical data were used for the odds ratio (OR), and continuous data were used for mean difference (SMD). The surface under the cumulative ranking (SUCRA) was employed to evaluate the incidence rate.

RESULTS

According to SUCRA results, daptomycin was the most effective treatment (73.0%) in bloodstream infections. In pulmonary infections and skin and soft tissue infections, linezolid out-performed other antibiotics in effectiveness rate (90.6% and 86.3%), microbial killing rate (93.3% and 93.1%). Vancomycin showed lower adverse reactions than teicoplanin, with less hepatotoxicity compared to linezolid and tigecycline. Linezolid had higher thrombocytopenia risk but lower nephrotoxicity risk than others. Vancomycin was less effective in microbial killing rates than linezolid across various infections.

CONCLUSION

The present research suggests that in pulmonary infections and skin and soft tissue infections, linezolid may be a better option for treating MRSA-related diseases. However, caution is warranted due to the association of linezolid with thrombocytopenia.

TRIAL REGISTRATION

Our study protocol was registered with the International Prospective Register of SystematicReviews (PROSPERO); Registration number: CRD42024535142.

The Impact of Fosfomycin on Gram Negative Infections: A Comprehensive Review

Multidrug-resistant or extended drug resistance has created havoc when it comes to patient treatment, as options are limited because of the spread of pathogens that are extensively or multidrug-resistant (MDR or XDR) and the absence of novel antibiotics that are effective against these pathogens. Physicians have therefore started using more established antibiotics such as polymyxins, tetracyclines, and aminoglycosides. Fosfomycin has just come to light as a result of the emergence of resistance to these medications since it continues to be effective against MDR and XDR bacteria that are both gram-positive and gram-negative. Fosfomycin, a bactericidal analogue of phosphoenolpyruvate that was formerly utilised as an oral medication for uncomplicated urinary tract infections, has recently attracted the interest of clinicians around the world. It may generally be a suitable therapy option for patients with highly resistant pathogenic infections, according to the advanced resistance shown by gram-negative bacteria. This review article aims to comprehensively evaluate the impact of fosfomycin on gram negative infections, highlighting its mechanism of action, pharmacokinetics, clinical efficacy, and resistance patterns.

Prevalence and Antibiotic Resistance Patterns of Methicillin-Resistant Staphylococcus aureus (MRSA) in a Hospital Setting: A Retrospective Study from 2018 to 2022

Methicillin-resistant Staphylococcus aureus (MRSA) is a highly infectious pathogen that poses a serious threat to human life and health. This study aimed to provide a scientific basis for the rational clinical use of antimicrobial drugs for treating MRSA infections and inform the development of preventive and control measures by analyzing the clinical distribution and resistance characteristics of MRSA in a hospital in Hebei China. To accomplish this, bacterial identification and drug sensitivity experiments were performed with 1858 Staphylococcus aureus (S. aureus) strains collected from a hospital from January 2018 to December 2022 using a phoenixTM-100 bacterial identification drug sensitivity analyzer. The experimental data were analyzed using WHONET 5.6 software, and the MRSA strains detected were analyzed for their clinical distribution and drug resistance. Of the 1858 S. aureus strains isolated, 429 were MRSA. Sputum samples had the highest MRSA detection rates (52.45%). Critical care medicine had the highest rate of MRSA (12.59%), followed by dermatology (9.79%). MRSA resistance to tetracycline increased by 13.9% over 5 years; resistance to quinupristin/dalfopristin also increased but remained low (1.9%). Resistance decreased to gentamicin, rifampicin, ciprofloxacin, and cotrimoxazole, though most significantly to erythromycin and clindamycin, exceeding 77% and 83%, respectively. No strains were resistant to vancomycin, teicoplanin, or linezolid, and drug resistance was most prevalent in patients ≥ 60 years old. This study will aid in improving the diagnosis and treatment of MRSA infections.

Therapeutic drug monitoring of antibiotics for methicillin-resistant Staphylococcus aureus infections: an updated narrative review for clinicians

BACKGROUND

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are associated with high mortality rates. Optimal antibiotic dosage plays a crucial role in reducing MRSA burden; thus, the use of therapeutic drug monitoring (TDM) in the clinical practice, especially of new drugs such as ceftobiprole, ceftaroline, dalbavancin, and oritavancin, should be implemented.

OBJECTIVES

We aim to examine and summarize the available evidence about TDM of anti-MRSA molecules, with a focus on pneumonia, endocarditis and vascular infections, and bone and joint infections.

SOURCES

We applied 'therapeutic drug monitoring' and 'Staphylococcus aureus' as search terms in PubMed, considering a time frame of 24 years (2001-2024). Articles in English language, non-duplicated, evaluating antibiotic therapeutic target, and role of TDM were included in the study.

CONTENT

In this review, available data for therapeutic target and TDM were critically analysed and summarized and suggestions about the use of old and new anti-MRSA antibiotics were provided, focusing on optimal dosages, tissue penetration according to infection types, and toxicity. Limitations to the widespread use of TDM in clinical practice were discussed.

IMPLICATIONS

The use of TDM may play an important role for the optimal management of patients with MRSA infections and may impact on patient outcomes by increasing efficacy and reducing the risk of adverse events. TDM may be implemented in clinical practice; however, several limitations such as the wide variability in the methodology and the need for skilled personnel need to be considered.

Assessment In vitro and In silico of the Activity of Thiadiazines as NorA Efflux Pump Inhibitors

Antimicrobials fight microorganisms, preventing and treating infectious diseases. However, antimicrobial resistance (AMR) is a growing concern due to the inappropriate and excessive use of these drugs. Several mechanisms can lead to resistance, including efflux pumps such as the NorA pump in Staphylococcus aureus, which reduces the effectiveness of fluoroquinolones. Thiadiazines are heterocyclic compounds whose chemical structure resembles that of cephalosporins. Therefore, these compounds and their derivatives have been studied for their potential in combating increased bacterial resistance. To analyze this hypothesis, direct activity assays, antibiotic action-modifying activity, fluorescence assays to evaluate the retention of ethidium bromide inside bacteria, and molecular docking were carried out. These experiments involved serial dilutions in microplates against Staphylococcus aureus strain 1199B under the influence of six thiadiazine derivatives (IJ10, IJ11, IJ21, IJ22, IJ23, and IJ25). The tests revealed that, despite not showing effective direct activity, some thiadiazine derivatives (IJ11, IJ21, and IJ22) inhibited the function of the bromide pump both in microdilution tests and in fluorescence and docking assays. Particularly, the IJ11 compound stood out for its activity similar to efflux inhibitors, as well as its inhibition of the norfloxacin pump of this bacterium. Among the results of this study, it deserves to be highlighted for anchoring future experiments, as it represents the first investigation of this group of thiadiazine derivatives against the NorA pump.

Microbiology and Epidemiology of Orbital Cellulitis in Pediatric and Young Adult Patients

INTRODUCTION

Using data from the large and geographically diverse Military Health System (MHS) beneficiary population, we aimed to characterize and update the epidemiology and microbiology of pediatric orbital cellulitis given previous data are limited to small, single-center studies.

MATERIALS AND METHODS

Following institutional review board approval, we performed a retrospective analysis using the Military Health System admissions, microbiology, and pharmacy data between June 2009 and September 2019. Patients less than 22 years of age with radiological confirmation of orbital cellulitis were included. Demographic data, presence of sinusitis, advanced imaging reports, blood and wound culture results with antibiotic susceptibilities, and antibiotic prescriptions were collected. Descriptive statistics were used to summarize demographic characteristics. Imaging findings were grouped by Chandler's stage (CS), an imaging-based measure of the progressive severity of orbital involvement. A Cochran-Armitage trend test was used to evaluate the relationship between CS and likelihood of positive confirmatory culture.

RESULTS

There was a male predominance (66.9%) and 55.5% of subjects had comorbid sinusitis. Of the 130 subjects included, 33.8% had one or more positive cultures, 30.8% had a positive wound culture, and 4.6% had a positive blood culture. The most identified organism was coagulase-negative staphylococci (23.3%), followed by Staphylococcus aureus (18.9%), Streptococcus intermedius (17.8%), and strict anaerobes as a group (13.3%). Gram-negative organisms were rare. Twenty-five percent of S. aureus were methicillin-resistant. Clindamycin resistance was identified in 9% of all S. aureus, 50% of coagulase-negative staphylococci, and 25% of S. intermedius. Clindamycin plus ceftriaxone was the most prescribed empiric antibiotic regimen (36.2%). Likelihood of a positive culture significantly increased with advancing CS.

CONCLUSIONS

Orbital cellulitis occurs most frequently in males with sinusitis. Likelihood of positive wound culture is increased with a more advanced CS. Staphylococcus and Streptococcus spp. and anaerobes are the most identified pathogens in orbital cellulitis, while gram-negative organisms are rare. Empiric antibiotic selection should include an anti-methicillin-resistant S. aureus agent combined with a broad-spectrum beta-lactam and anaerobic coverage.

Staphylococcus aureus Tetracycline Resistance and Co-resistance in a Doxy-PEP-Eligible Population

In Staphylococcus aureus infections in men eligible for doxycycline post-exposure prophylaxis (doxy-PEP), tetracycline non-susceptibility is more prevalent than in the overall population and is associated with resistance to trimethoprim-sulfamethoxazole and clindamycin. Doxy-PEP may select for S. aureus multi-drug resistance, underscoring the importance of surveillance.

Synthesized Bis-Triphenyl Phosphonium-Based Nano Vesicles Have Potent and Selective Antibacterial Effects on Several Clinically Relevant Superbugs

The increasing emergence of multidrug-resistant (MDR) pathogens due to antibiotic misuse translates into obstinate infections with high morbidity and high-cost hospitalizations. To oppose these MDR superbugs, new antimicrobial options are necessary. Although both quaternary ammonium salts (QASs) and phosphonium salts (QPSs) possess antimicrobial effects, QPSs have been studied to a lesser extent. Recently, we successfully reported the bacteriostatic and cytotoxic effects of a triphenyl phosphonium salt against MDR isolates of the Enterococcus and Staphylococcus genera. Here, aiming at finding new antibacterial devices possibly active toward a broader spectrum of clinically relevant bacteria responsible for severe human infections, we synthesized a water-soluble, sterically hindered quaternary phosphonium salt (BPPB). It encompasses two triphenyl phosphonium groups linked by a C12 alkyl chain, thus embodying the characteristics of molecules known as bola-amphiphiles. BPPB was characterized by ATR-FTIR, NMR, and UV spectroscopy, FIA-MS (ESI), elemental analysis, and potentiometric titrations. Optical and DLS analyses evidenced BPPB tendency to self-forming spherical vesicles of 45 nm (DLS) in dilute solution, tending to form larger aggregates in concentrate solution (DLS and optical microscope), having a positive zeta potential (+18 mV). The antibacterial effects of BPPB were, for the first time, assessed against fifty clinical isolates of both Gram-positive and Gram-negative species. Excellent antibacterial effects were observed for all strains tested, involving all the most concerning species included in ESKAPE bacteria. The lowest MICs were 0.250 µg/mL, while the highest ones (32 µg/mL) were observed for MDR Gram-negative metallo-β-lactamase-producing bacteria and/or species resistant also to colistin, carbapenems, cefiderocol, and therefore intractable with currently available antibiotics. Moreover, when administered to HepG2 human hepatic and Cos-7 monkey kidney cell lines, BPPB showed selectivity indices > 10 for all Gram-positive isolates and for clinically relevant Gram-negative superbugs such as those of E. coli species, thus being very promising for clinical development.

Biguanide-Vancomycin Conjugates are Effective Broad-Spectrum Antibiotics against Actively Growing and Biofilm-Associated Gram-Positive and Gram-Negative ESKAPE Pathogens and Mycobacteria

Strategies to increase the efficacy and/or expand the spectrum of activity of existing antibiotics provide a potentially fast path to clinically address the growing crisis of antibiotic-resistant infections. Here, we report the synthesis, antibacterial efficacy, and mechanistic activity of an unprecedented class of biguanide-antibiotic conjugates. Our lead biguanide-vancomycin conjugate, V-C6-Bg-PhCl (5e), induces highly effective cell killing with up to a 2 orders-of-magnitude improvement over its parent compound, vancomycin (V), against vancomycin-resistant enterococcus. V-C6-Bg-PhCl (5e) also exhibits improved activity against mycobacteria and each of the ESKAPE pathogens, including the Gram-negative organisms. Furthermore, we uncover broad-spectrum killing activity against biofilm-associated Gram-positive and Gram-negative bacteria as well as mycobacteria not observed for clinically used antibiotics such as oritavancin. Mode-of-action studies reveal that vancomycin-like cell wall synthesis inhibition with improved efficacy attributed to enhanced engagement at vancomycin binding sites through biguanide association with relevant cell-surface anions for Gram-positive and Gram-negative bacteria. Due to its potency, remarkably broad activity, and lack of acute mammalian cell toxicity, V-C6-Bg-PhCl (5e) is a promising candidate for treating antibiotic-resistant infections and notoriously difficult-to-treat slowly growing and antibiotic-tolerant bacteria associated with chronic and often incurable infections. More generally, this study offers a new strategy (biguanidinylation) to enhance antibiotic activity and facilitate clinical entry.

Prevalence and risk factors for haematogenous periprosthetic joint infection during Staphylococcus aureus bacteraemia

BACKGROUND

Staphylococcus aureus bacteraemia (SAB) may lead to periprosthetic joint infections (PJI) via haematogenous spread of bacteria to the joint. Due to the risk of PJI, patients with SAB and prosthetic joint are recommended prolonged antibiotic treatment. The aim of the study was to assess the risk of PJI during SAB, and to evaluate if short treatment duration affects outcomes in patients with uncomplicated SAB and prosthetic joints without clinical signs of PJI.

METHODS

Patients with growth of S. aureus in blood cultures were cross-referenced against the Swedish Arthroplasty register to identify patients with prosthetic hip or knee joints at the time of SAB. Medical records were reviewed to identify PJI at the time of SAB and during a 6-month follow-up period.

RESULTS

Out of 400 patients with SAB and a prosthetic joint, 281 met all eligibility criteria and were included in the study. Of the included participants, 35 (12%) had a haematogenous PJI. Younger age and presence of multiple prosthetic joints were associated with an increased risk of PJI. Of the 247 patients without signs of PJI at the initial SAB episode, 118 patients (48%) had an uncomplicated infection and received short total antibiotic treatment (median 15 days, IQR 13-17). The risk of PJI during the follow-up period was low (<1%) and similar in the uncomplicated group compared to patients with complicated SAB that received longer antibiotic treatment (median 29 days, IQR 15-70).

CONCLUSION

The prevalence of haematogenous PJI was lower than previously reported. Our data do not support prolonged antibiotic treatment in patients with SAB and prosthetic joints without clinical signs of PJI.

Insights into the molecular basis of reduced vancomycin susceptibility among three prominent Staphylococcus aureus clonal complexes

Staphylococcus aureus is a leading cause of healthcare-associated infections globally. Vancomycin-resistant S. aureus (VRSA), those with high-level resistance [minimum inhibitory concentration (MIC) of 16-32 µg/mL vancomycin], are uncommon, whereas vancomycin-intermediate S. aureus (VISA; MIC of 4-8 µg/mL), are isolated more frequently and develop during long-term and/or repeated use of the antibiotic. VISA can be difficult to eradicate and infections may persist. Our knowledge of mechanisms that underlie the development of VISA is incomplete. We used a genomics approach to investigate the VISA phenotype in three prominent S. aureus lineages. All VISA clinical isolates tested had increased cell wall thickness compared with vancomycin-susceptible S. aureus strains. Growth rates of clonal complex (CC) 5, CC8, and CC45 clinical isolates were reduced in 2 µg/mL vancomycin compared to media alone. Culture in 2 and 4 µg/mL vancomycin sequentially for two weeks reduced susceptibility to daptomycin, televancin, tigecycline, and vancomycin in a majority of CC5, CC8, and CC45 isolates tested. We identified alleles reported previously to contribute to the VISA phenotype, but unexpectedly, these alleles were unique to each CC. A subtherapeutic concentration of vancomycin elicited changes in the VISA transcriptome-common and unique-among the three CCs tested. Multiple genes, including those encoding a glycerate kinase, an M50 family metallopeptidase, and an uncharacterized membrane protein, were upregulated among all three lineages and not reported previously as associated with VISA. Although there are lineage-specific changes in DNA sequence, our findings suggest changes in the VISA transcriptome constitute a general response to stress that confers reduced susceptibility to multiple antibiotics.

IMPORTANCE

Our understanding of the mechanisms that underlie the development of vancomycin-intermediate Staphylococcus aureus (VISA) is incomplete. To provide a more comprehensive view of this process, we compared genome sequences of clonal complex (CC) 5, CC8, and CC45 VISA clinical isolates and measured changes in the transcriptomes of these isolates during culture with a subtherapeutic concentration of vancomycin. Notably, we identified differentially expressed genes that were lineage-specific or common to the lineages tested, including genes that have not been previously reported to contribute to a VISA phenotype. Changes in gene expression were accompanied by reduced growth rate, increased cell wall thickness, and reduced susceptibility to daptomycin, televancin, tigecycline, and vancomycin. Our results provide support to the idea that changes in gene expression contribute to the development of VISA among three CCs that are a prominent cause of human infections.

Comparison of antimicrobial therapy termination in febrile and afebrile patients with acute cholangitis after drainage

The standard treatment duration for acute cholangitis (AC) involves a 4-7-day antimicrobial treatment post-biliary drainage; however, recent studies have suggested that a ≤ 2-3 days is sufficient. However, clinical practice frequently depends on body temperature as a criterion for discontinuing antimicrobial treatment. Therefore, in this study, we assessed whether patients with AC can achieve successful outcomes with a ≤ 7-day antimicrobial treatment, even with a fever, assuming the infection source is effectively controlled. We conducted a single-center retrospective study involving patients with AC, defined following the Tokyo Guidelines 2018 for any cause, who underwent successful biliary drainage and completed a ≤ 7-day antimicrobial treatment. Patients were categorized into the febrile and afebrile groups based on their body temperature within 24 h before completing antimicrobial treatment. The primary outcome was the clinical cure rate, defined as no initial presenting symptoms by day 14 post-biliary drainage without recurrence or death by day 30. The secondary outcome was a 3-month recurrence rate. Logistic regression with inverse probability of treatment weighting was used. Overall, 408 patients were selected, among whom 40 (9.8%) were febrile. The two groups showed no significant differences in the clinical cure and 3-month recurrence rates. Notably, the subgroups limited to patients with a ≤ 3-day antibiotic treatment duration also showed no differences in these outcomes. Therefore, our results suggest that discontinuing antibiotics within the initially planned treatment period was sufficient for successful drainage cases of AC, regardless of the patient's fever status during the 24 h leading up to termination.

Adherence to and clinical utility of "quality indicators" for Staphylococcus aureus bacteremia: a retrospective, multicenter study

BACKGROUND

We aimed to improve the prognosis, treatment, and management of Staphylococcus aureus bacteremia (SAB) by evaluating the association between adherence to quality indicators (QIs) and clinical outcomes in patients with their clinical outcomes.

METHODS

We retrospectively collected clinical and microbiological data on hospitalized patients with SAB from 14 hospitals (three with >  600, two with 401-600, five with 201-400, and four with ≤ 200 beds) in Japan from January to December 2022. The SAB management quality was evaluated using the SAB-QI score (ranging from 0 to 13 points), which consists of 13 QIs (grouped into five categories) based on previous literature.

RESULTS

Of the 4,448 positive blood culture episodes, 289 patients with SAB (6.5%) were enrolled. The SAB-QI scores ranged from 3 to 13, with a median score of 9 points. The SAB-QI score was highest in middle-sized hospitals with 401-600 beds. Adherence to each of the four QI categories (blood culture, echocardiography, source control, and antibiotic treatment) was significantly higher in survived cases than in fatal cases. Kaplan-Meier curves with log-rank tests demonstrated that higher adherence to SAB-QIs indicated a better prognosis. Logistic regression analysis revealed that age, methicillin resistance, multiple comorbidities (≥ 2), and low SAB-QI score were significantly associated with 30-day mortality in patients with SAB.

CONCLUSIONS

Our study highlights that greater adherence to the SAB-QIs correlates with improved patient outcomes. Management of patients with SAB should follow these recommended indicators to maintain the quality of care, especially for patients with poor prognosticators.

Fixed dose daptomycin: An opportunity for pharmacokinetic/pharmacodynamic optimization in Staphylococcus aureus infections

BACKGROUND

Daptomycin is a high-use intravenous antimicrobial agent affording the convenience of once-daily dosing. Prior studies suggest an opportunity to use a more operationally convenient fixed rather than weight-based dosing but this approach has not been studied prospectively.

METHODS

This study quantified the probability of toxicity and efficacy end points by prospectively testing a fixed dose regimen of daptomycin (750 mg) in obese and non-obese adults. At least, three daptomycin concentrations were measured at steady-state for each patient. A population pharmacokinetic model was constructed to evaluate concentration-time profiles and investigate covariates of daptomycin clearance. Simulations were performed to evaluate the probability of achieving efficacy (24-h area under the curve (AUC0-24) ≥ 666 mg∙h/L) and toxicity (minimum concentration (C min) ≥24.3 mg/L) targets for fixed (500-1000 mg) and weight-based (6-12 mg/kg) daptomycin doses.

RESULTS

Thirty-one patients (16 females, 15 males) with median (interquartile range (IQR)) age of 50 (30, 62) years and weight of 74 (54, 156) kg were included in the final analysis. Fixed dose daptomycin (750 mg) resulted in similar exposure across weights with a median (IQR) AUC0-24 of 819 (499, 1501) mg∙h/L and 749 (606, 1265) mg∙h/L in patients weighing ≤74 kg and >74 kg, respectively. Overall, male sex and increased kidney function necessitate higher fixed and weight-based doses to achieve efficacy. Creatine phosphokinase elevation was observed in two patients (6.5%) and predicted to be lower with fixed versus weight-based regimens.

CONCLUSIONS

Fixed daptomycin dosing adjusted for sex and kidney function is expected to improve the efficacy-to-toxicity ratio, transitions of care, and costs compared to weight-based doses. However, no empiric dosing approach is predicted to achieve ≥90% efficacy while minimizing the risk of toxicity, so therapeutic drug monitoring should be considered on a patient-specific basis.

Guidelines for Antibiotics Prescription in Critically Ill Patients

How to cite this article: Khilnani GC, Tiwari P, Mittal S, Kulkarni AP, Chaudhry D, Zirpe KG, et al. Guidelines for Antibiotics Prescription in Critically Ill Patients. Indian J Crit Care Med 2024;28(S2):S104-S216.

Epidemiology and clinical relevance of persistent bacteraemia in patients with Gram-negative bloodstream infection: a retrospective cohort study

OBJECTIVES

The risk factors and outcomes associated with persistent bacteraemia in Gram-negative bloodstream infection (GN-BSI) are not well described. We conducted a follow-on analysis of a retrospective population-wide cohort to characterize persistent bacteraemia in patients with GN-BSI.

METHODS

We included all hospitalized patients >18 years old with GN-BSI between April 2017 and December 2021 in Ontario who received follow-up blood culture (FUBC) 2-5 days after the index positive blood culture. Persistent bacteraemia was defined as having a positive FUBC with the same Gram-negative organism as the index blood culture. We identified variables independently associated with persistent bacteraemia in a multivariable logistic regression model. We evaluated whether persistent bacteraemia was associated with increased odds of 30- and 90-day all-cause mortality using multivariable logistic regression models adjusted for potential confounders.

RESULTS

In this study, 8807 patients were included; 600 (6.8%) had persistent bacteraemia. Having a permanent catheter, antimicrobial resistance, nosocomial infection, ICU admission, respiratory or skin and soft tissue source of infection, and infection by a non-fermenter or non-Enterobacterales/anaerobic organism were associated with increased odds of having persistent bacteraemia. The 30-day mortality was 17.2% versus 9.6% in those with and without persistent bacteraemia (aOR 1.65, 95% CI 1.29-2.11), while 90-day mortality was 25.5% versus 16.9%, respectively (aOR 1.53, 95% CI 1.24-1.89). Prevalence and odds of developing persistent bacteraemia varied widely depending on causative organism.

CONCLUSIONS

Persistent bacteraemia is uncommon in GN-BSI but is associated with poorer outcomes. A validated risk stratification tool may be useful to identify patients with persistent bacteraemia.

Determining steady-state trough range in vancomycin drug dosing using machine learning

BACKGROUND

Vancomycin is a renally eliminated, nephrotoxic, glycopeptide antibiotic with a narrow therapeutic window, widely used in intensive care units (ICU). We aimed to predict the risk of inappropriate vancomycin trough levels and appropriate dosing for each ICU patient.

METHODS

Observed vancomycin trough levels were categorized into sub-therapeutic, therapeutic, and supra-therapeutic levels to train and compare different classification models. We included adult ICU patients (≥ 18 years) with at least one vancomycin concentration measurement during hospitalization at Mayo Clinic, Rochester, MN, from January 2007 to December 2017.

RESULT

The final cohort consisted of 5337 vancomycin courses. The XGBoost models outperformed other machine learning models with the AUC-ROC of 0.85 and 0.83, specificity of 53% and 47%, and sensitivity of 94% and 94% for sub- and supra-therapeutic categories, respectively. Kinetic estimated glomerular filtration rate and other creatinine-based measurements, vancomycin regimen (dose and interval), comorbidities, body mass index, age, sex, and blood pressure were among the most important variables in the models.

CONCLUSION

We developed models to assess the risk of sub- and supra-therapeutic vancomycin trough levels to improve the accuracy of drug dosing in critically ill patients.

Outcomes of Acute Kidney Injury among Hospitalized Patients with Infective Endocarditis: A National Inpatient Sample Analysis

Background/Objectives: Patients with infective endocarditis (IE) are more susceptible to acute kidney injury (AKI). The presence of AKI increases in-hospital complications in these patients. Methods: The 2016-2020 National Inpatient Sample (NIS) database consisting of adult admissions with IE and AKI was utilized. The primary outcome was all-cause inpatient mortality. Secondary outcomes included fluid and electrolyte disorders, stroke, septic arterial embolism, septic shock, cardiogenic shock, valve surgery, vasopressor support, mechanical ventilation, length of stay (LOS), and total hospital charges. Results: Out of a total of 63,725 adult admissions with IE, 16,295 (25.5%) admissions had AKI. Patients with AKI were more likely to be males (63% vs. 57.6%, p < 0.001) and older (55.8 vs. 50.4, p < 0.001). A higher proportion of these patients were admitted to large hospitals (60.6 vs. 55.3%, p < 0.001) and urban teaching hospitals (81.9 vs. 75%, p < 0.001). Patients with AKI had higher LOS (17 ± 16.1 vs. 11.32 ± 11.7, p < 0.001) and hospital charges (USD 239,046.8 ± 303,977.3 vs. USD 124,857.6 ± 192,883.5, p < 0.001). Multivariable analysis showed higher odds of all-cause inpatient mortality (aOR: 2.22, 95% CI: 1.81-2.73, p < 0.001). They also had higher risk for fluid and electrolyte disorder (aOR: 2.31, 95% CI: 2.10-2.53, p < 0.001), septic arterial embolism (aOR: 1.61, 95% CI: 1.42-1.84, p < 0.001), septic shock (aOR: 3.78, 95% CI: 2.97-4.82, p < 0.001), cardiogenic shock (OR: 3.37, 95% CI: 2.65-4.28, p < 0.001), valve surgery (aOR: 1.52, 95% CI: 1.35-1.71, p < 0.001), vasopressor requirement (aOR: 1.99, 95% CI: 1.52-2.60, p < 0.001), and mechanical ventilation (aOR: 2.75, 95% CI: 2.33-3.24, p < 0.001). The association with stroke was elevated but not statistically significant. Conclusions: This large retrospective analysis demonstrated that patients with AKI and infective endocarditis had increased mortality, adverse hospital outcomes, increased LOS, and hospital costs.

Impact of a Bundle of Interventions on Quality-of-Care Indicators for Staphylococcus aureus Bacteraemia: A Single-Centre, Quasi-Experimental, Before-After Study

Staphylococcus aureus bacteraemia (SAB) is a life-threatening bloodstream infection. Improved adherence to quality-of-care indicators (QCIs) can significantly enhance patient outcomes. This quasi-experimental study evaluated the impact of a bundle of interventions on QCI adherence in adult patients with SAB. Additionally, a molecular rapid diagnostic test (mRDT) for S. aureus and methicillin resistance was introduced during weekdays. We compared pre-intervention (January-December 2022) and post-intervention (May 2023-April 2024) data on QCI adherence and time to appropriate treatment. A total of 56 and 40 SAB episodes were included in the pre- and post-intervention periods, respectively. Full QCI adherence significantly increased from 28.6% to 67.5% in the post-intervention period (p < 0.001). The mRDT diagnosed SAB in eight cases (26.6%), but the time to achieve appropriate target therapy did not improve in the post-intervention period (54 h (IQR 30-74) vs. 72 h (IQR 51-83), p = 0.131). The thirty-day mortality rate was comparable between the two periods (17.9% vs. 12.5%, p = 0.476). This study demonstrates that a bundle of interventions can substantially improve adherence to SAB management QCIs.

Genomic investigation and clinical correlates of the in vitro β-lactam: NaHCO3 responsiveness phenotype among methicillin-resistant Staphylococcus aureus isolates from a randomized clinical trial

NaHCO3 responsiveness is a novel phenotype where some methicillin-resistant Staphylococcus aureus (MRSA) isolates exhibit significantly lower minimal inhibitory concentrations (MIC) to oxacillin and/or cefazolin in the presence of NaHCO3. NaHCO3 responsiveness correlated with treatment response to β-lactams in an endocarditis animal model. We investigated whether treatment of NaHCO3-responsive strains with β-lactams was associated with faster clearance of bacteremia. The CAMERA2 trial (Combination Antibiotics for Methicillin-Resistant Staphylococcus aureus) randomly assigned participants with MRSA bloodstream infections to standard therapy, or to standard therapy plus an anti-staphylococcal β-lactam (combination therapy). For 117 CAMERA2 MRSA isolates, we determined by broth microdilution the MIC of cefazolin and oxacillin, with and without 44 mM of NaHCO3. Isolates exhibiting ≥4-fold decrease in the MIC to cefazolin or oxacillin in the presence of NaHCO3 were considered "NaHCO3-responsive" to that agent. We compared the rate of persistent bacteremia among participants who had infections caused by NaHCO3-responsive and non-responsive strains, and that were assigned to combination treatment with a β-lactam. Thirty-one percent (36/117) and 25% (21/85) of MRSA isolates were NaHCO3-responsive to cefazolin and oxacillin, respectively. The NaHCO3-responsive phenotype was significantly associated with sequence type 93, SCCmec type IVa, and mecA alleles with substitutions in positions -7 and -38 in the regulatory region. Among participants treated with a β-lactam, there was no association between the NaHCO3-responsive phenotype and persistent bacteremia (cefazolin, P = 0.82; oxacillin, P = 0.81). In patients from a randomized clinical trial with MRSA bloodstream infection, isolates with an in vitro β-lactam-NaHCO3-responsive phenotype were associated with distinctive genetic signatures, but not with a shorter duration of bacteremia among those treated with a β-lactam.

Real-World Use and Treatment Outcomes of Ceftaroline Fosamil in Patients with Complicated Skin and Soft Tissue Infection: A Multinational Retrospective Study

Background

Ceftaroline fosamil is approved for the treatment of complicated skin and soft tissue infections (cSSTI) and community-acquired pneumonia (CAP); however, data on its real-world use and effectiveness in Europe and Latin America are currently limited. This retrospective observational study assessed ceftaroline fosamil use and treatment outcomes in adults hospitalized with cSSTI or CAP treated with ceftaroline fosamil in a usual care setting in Europe and Latin America. Results for patients with cSSTI are reported.

Methods

Data from patients with cSSTI who received ≥4 consecutive intravenous ceftaroline fosamil doses up to May 31, 2019, were collected from sites in Brazil, Colombia, France, Greece, Italy, and Spain. Patient characteristics, clinical management, hospitalization information, microbiological diagnosis, and clinical responses were summarized descriptively. Healthcare resource use variables were evaluated by clinical response to ceftaroline fosamil.

Results

Data for 132 patients were included (58.3% male; mean age 58.5 years). Most common lesions were cellulitis/fasciitis (62.1%), abscess (34.1%), and post-surgical wounds (19.7%). Pathogens most frequently identified were methicillin-resistant (18.2%) and methicillin-susceptible Staphylococcus aureus (17.4%). Median (range) ceftaroline fosamil treatment duration was 8 (2-60) days (daily doses of 1200 [400-2400] mg); 78 patients (59.1%) received monotherapy. In total, 75 (56.8%) patients had additional antibiotics after ceftaroline fosamil. Clinical response occurred in 118 (89.4%) patients. All-cause 30-day readmission occurred in 13 (9.8%) patients, and all-cause 30-day mortality in 7 (5.3%). Clinical response to ceftaroline was associated with >25% shorter length of hospital and intensive care stay, and with ~40% lower hospital costs, versus non-responders.

Conclusion

Ceftaroline fosamil was effective in treating adults with cSSTI and clinical response to ceftaroline fosamil was associated with reductions in healthcare resource use compared with non-responders, in Europe and Latin America.

Clinicaltrialsgov Identifier

NCT04198571.

Population pharmacokinetics of daptomycin in critically ill patients receiving extracorporeal membrane oxygenation

BACKGROUND

Daptomycin is widely used in critically ill patients for Gram-positive bacterial infections. Extracorporeal membrane oxygenation (ECMO) is increasingly used in this population and can potentially alter the pharmacokinetic (PK) behaviour of antibiotics. However, the effect of ECMO has not been evaluated in daptomycin. Our study aims to explore the effect of ECMO on daptomycin in critically ill patients through population pharmacokinetic (PopPK) analysis and to determine optimal dosage regimens based on both efficacy and safety considerations.

METHODS

A prospective, open-label PK study was carried out in critically ill patients with or without ECMO. The total concentration of daptomycin was determined by UPLC-MS/MS. NONMEM was used for PopPK analysis and Monte Carlo simulations.

RESULTS

Two hundred and ninety-three plasma samples were collected from 36 critically ill patients, 24 of whom received ECMO support. A two-compartment model with first-order elimination can best describe the PK of daptomycin. Creatinine clearance (CLCR) significantly affects the clearance of daptomycin while ECMO has no significant effect on the PK parameters. Monte Carlo simulations showed that, when the MICs for bacteria are  ≥1 mg/L, the currently recommended dosage regimen is insufficient for critically ill patients with CLCR > 30 mL/min. Our simulations suggest 10 mg/kg for patients with CLCR between 30 and 90 mL/min, and 12 mg/kg for patients with CLCR higher than 90 mL/min.

CONCLUSIONS

This is the first PopPK model of daptomycin in ECMO patients. Optimal dosage regimens considering efficacy, safety, and pathogens were provided for critical patients based on pharmacokinetic-pharmacodynamic analysis.

Role of tcaA, a potential target as a ceftobiprole resistance breaker in MRSA β-lactam resistance

OBJECTIVES

Using a random forest algorithm, we previously found that teicoplanin-associated gene A (tcaA) might play a role in resistance of methicillin-resistant Staphylococcus aureus (MRSA) to β-lactams, which we have investigated further here.

METHODS

Representative MRSA strains of prevalent clones were selected to identify the role of tcaA in the MRSA response to β-lactams. tcaA genes were deleted by homologous recombination in the selected MRSA strains, and antibiotic susceptibility tests were applied to evaluate the effect of tcaA on the minimum inhibitory concentrations (MICs) of glycopeptides and β-lactams. Scanning electron microscopy, RNA sequencing, and quantitative reverse transcription-polymerase chain reaction were performed to explore the mechanism of tcaA in MRSA resistance to β-lactams.

RESULTS

The MIC of penicillin plus clavulanate decreased from 3 mg/L to 0.064 mg/L and that of oxacillin decreased from 16 to 0.5 mg/L when tcaA was knocked out in the LAC strain. Compared with wild-type MRSA isolates, when tcaA was deleted, all selected strains were more susceptible to β-lactams. Susceptibility to ceftobiprole was restored in the ceftobiprole-resistant strain when tcaA was deleted. tcaA knockout caused "log-like" abnormal division of MRSA, and tcaA deficiency mediated low expression of mecA, ponA, and murA2.

CONCLUSIONS

Machine learning is a reliable tool for identifying drug resistance-related genes. tcaA may be involved in S. aureus cell division and may affect mecA, ponA, and murA2 expression. Furthermore, tcaA is a potential resistance breaker target for β-lactams, including ceftobiprole, in MRSA.

Secondary Bacterial Infections in Patients with Atopic Dermatitis or Other Common Dermatoses

Secondary bacterial infections of common dermatoses such as atopic dermatitis, ectoparasitosis, and varicella zoster virus infections are frequent, with Staphylococcus aureus and Streptococcus pyogenes being the bacteria most involved. There are also Gram-negative infections secondary to common dermatoses such as foot dyshidrotic eczema and tinea pedis. Factors favoring secondary bacterial infections in atopic dermatitis, ectoparasitosis, and varicella zoster virus infections mainly include an epidermal barrier alteration as well as itch. Mite-bacteria interaction is also involved in scabies and some environmental factors can promote Gram-negative bacterial infections of the feet. Furthermore, the bacterial ecology of these superinfections may depend on the geographical origin of the patients, especially in ectoparasitosis. Bacterial superinfections can also have different clinical aspects depending on the underlying dermatoses. Subsequently, the choice of class, course, and duration of antibiotic treatment depends on the severity of the infection and the suspected bacteria, primarily targeting S. aureus. Prevention of these secondary bacterial infections depends first and foremost on the management of the underlying skin disorder. At the same time, educating the patient on maintaining good skin hygiene and reporting changes in the primary lesions is crucial. In the case of recurrent secondary infections, decolonization of S. aureus is deemed necessary, particularly in atopic dermatitis.

Follow-up blood cultures do not reduce mortality in hospitalized patients with Gram-negative bloodstream infection: a retrospective population-wide cohort study

OBJECTIVES

The utility of follow-up blood cultures (FUBCs) in patients with Gram-negative bloodstream infection (GN-BSI) is controversial. Observational studies have suggested significant mortality benefit but may be limited by single-centre designs, immortal time bias, and residual confounding. We examined the impact of FUBCs on mortality in patients with GN-BSI in a retrospective population-wide cohort study in Ontario, Canada.

METHODS

Adult patients with GN-BSI hospitalized between April 2017 and December 2021 were included. Primary outcome was all-cause mortality within 30 days. FUBC was treated as a time-varying exposure. Secondary outcomes were 90-day mortality, length of stay, and number of days alive and out of hospital at 30 and 90 days.

RESULTS

Thirty-four thousand one hundred patients were included; 8807 (25.8%) patients received FUBC, of which 966 (11.0%) were positive. Median proportion of patients receiving FUBC was 18.8% (interquartile range, 10.0-29.7%; range, 0-66.1%) across 101 hospitals; this correlated with positivity and contamination rate. Eight hundred ninety (10.1%) patients in the FUBC group and 2263 (8.9%) patients in the no FUBC group died within 30 days. In the fully adjusted model, there was no association between FUBC and mortality (hazard ratio, 0.97; 95% CI, 0.90-1.04). Patients with FUBC had significantly longer length of stay (median, 11 vs. 7 days; adjusted risk ratio, 1.18; 95% CI, 1.16-1.21) and fewer number of days alive and out of hospital at 30 and 90 days.

DISCUSSION

FUBC collection in patients with GN-BSI varies widely across hospitals and may be associated with prolonged hospitalization without clear survival benefit. Residual confounding may be present given the observational design. Clear benefit should be demonstrated in a randomized trial before widespread adoption of routine FUBC.