Impact of Time to Appropriate Therapy on Mortality in Patients with Vancomycin-Intermediate Staphylococcus aureus Infection

Appropriate use of vancomycin in a cardiac surgical unit

BACKGROUND

Antibiotic resistance is a rapidly growing problem. Methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are major worries, particularly in developing nations where cost-effectiveness is essential. Use of vancomycin must be restricted to prevent resistant to it. Examining the appropriateness rate of vancomycin use in light of the recommendations of the Infectious Disease Society of America (IDSA) in the cardiac surgery ward was the aim of this study.

METHODOLOGY

This study was a retrospective analysis of the medical records of patients who received vancomycin over the previous year, from January 2023 to December 2023. The collected patient data included demographics, indications for vancomycin use, culture and sensitivity test results, concurrent antibiotic medications, vancomycin serum levels, and diagnoses. The appropriateness of vancomycin use was classified according to the recommendations of the Infectious Diseases Society of America (IDSA).

RESULTS

A total of 294 patients received vancomycin. The appropriate use of vancomycin was significantly higher than its inappropriate use (p = 0.001). Approximately 41% (n = 120) of patients were administered vancomycin for treatment purposes, while the remainder received it empirically, but not as surgical prophylaxis. Appropriate use of vancomycin was observed in 89.1% (n = 262) of patients. However, there remained a notable rate of inappropriate vancomycin use (n = 32, 10.9%). The most common reason for inappropriate use was the continuation of vancomycin beyond 72 h without further evidence of a Gram-positive infection (n = 21, accounting for 65.6% of all inappropriate use).

CONCLUSIONS

The current study demonstrated that 89.1% of vancomycin use was appropriate, while approximately 10% was inappropriate, potentially contributing to vancomycin resistance. The majority of inappropriate use stems from frequent empirical prescribing, which requires further review and monitoring.

Severe Skin and Soft-Tissue Infections

Skin and soft-tissue infections (SSTIs) are a common reason for hospital admission. Severe SSTIs, particularly necrotizing infections, often require intensive care. Source control (often with surgical debridement) and broad-spectrum antimicrobials are paramount for minimizing significant morbidity and mortality. Rapid diagnostic tests may help in selection and de-escalation of antimicrobials for SSTIs. Besides early source control and early effective antimicrobial therapy, other patient-level factors such as comorbidities and immune status play a role in clinical outcomes. Intravenous immunoglobulin continues to be studied for severe SSTI, though recruitment in trials continues to be an issue. Severe SSTIs are complex to manage, due in part to regional variation in predominant pathogens and antimicrobial resistance patterns, as well as variations in host immune responses. This review includes descriptions of source control, antimicrobial therapies, intravenous immunoglobulin, and hyperbaric oxygen therapy, as well as host factors in severe SSTIs.

A novel mutation of walK confers vancomycin-intermediate resistance in methicillin-susceptible Staphylococcus aureus

With the treatment failure by vancomycin and poor clinical outcomes, the emergence and spread of vancomycin intermediate-resistant Staphylococcus aureus (VISA) has raised more concerns in recent years. While most VISA strains are isolated from methicillin-resistant S. aureus (MRSA), the mechanism underlying the generation of VISA from methicillin-susceptible S. aureus (MSSA) is still largely unknown. Here, we identified a total of 10 mutations in 9 genes through comparative genome analysis from laboratory-derived VISA strain. We verified the role of a novel mutation of WalK (I237T) and our results further indicated that the introduction of WalK (I237T) by allelic replacement can confer vancomycin resistance in MSSA with common VISA characteristics, including thickened cell walls, reduced autolysis, and attenuated virulence. Consistent with these phenotypes, real-time quantitative reverse transcription-PCR revealed the altered expression of several genes associated with cell wall metabolism and virulence control. In addition, electrophoretic mobility shift assay indicated that WalR can directly bind to the promoter regions of oatA, sle1, and mgt, fluorescence-based promoter activity and β-galactosidase assays revealed WalK (I237T) can alter promoter activities of oatA, mgt, and sle1, thus regulating genes expression. These findings broaden our understanding of the regulatory network by WalKR system and decipher the molecular mechanisms of developmental VISA resistance in MSSA with point mutations.

Treatment of Necrotizing Soft Tissue Infections: Antibiotics

Necrotizing soft tissue infections (NSTIs) are severe, life-threatening infections, and early therapeutic intervention is essential. Prompt administration of potent antimicrobial agents is pivotal, but inadequate empirical therapy is unfortunately common. Optimization of the antibiotic treatment strategy in NSTIs requires consideration of local epidemiology of causative pathogens and antimicrobial resistance patterns, knowledge on common pathogenetic mechanisms in NSTIs, and adaptations to pharmacokinetic and pharmacodynamic physiological changes in critically ill patients. In the present article we address all these issues, as well as review and compare contemporary guidelines for antimicrobial treatment of NSTIs from around the world.

High sensitivity versus low level of vancomycin needs to be concern for another alternative anti- Staphylococcus aureus as the first- line antibiotic

Background and aim: Vancomycin has been the first-line therapy for MRSA infection disease for many years. According to standard guidelines, the therapeutic vancomycin trough concentration should be above 10 mg/L and optimally between 15-20 mg/L. The aim of this study was to evaluate vancomycin trough level concentration in patients infected with MRSA.Methods: This cross- sectional study included a sample of 170 patients admitted to the ICU of Loghman hospital. We used a standard questionnaire, then applied appropriate statistical tests. All collected data had been analyzed and interpreted by IBM SPSS Statistics 19.0.Results: Among this study population, 71.8% was male. Just 20.8% of the patients can reach the therapeutic level trough even after changing the dose. It should be noted that a significant percentage of toxicity was observed after increasing the dose. Conclusions: Even though high sensitivity against vancomycin disc has been seen in antibiogram tests, sufficient efficiency has not been distinguished, in the sense that, just a few patients by low trough level concentration, reached to therapeutic level after the dose change. Based on some sources, because of the side effects and limited safe range of vancomycin, we should consider a new approach to the alternative antibiotics. (www.actabiomedica.it)

Trimetoprim-sulfametoxazole in ventilator-associated pneumonia: a cohort study

To evaluate the effectiveness of trimetoprim-sulfametoxazole (TMP-SMX) for treatment of ventilator-associated pneumonia (VAP). A retrospective cohort study including patients with VAP from 2011 to 2017. Two groups were analysed: TMP-SMX group, including patients who had received TMP-SMX (as first-line and as de-escalation), and No-TMP-SMX group, including patients who had not received TMP-SMX treatment. Primary clinical outcome was mortality at 30 days from starting the antibiotic treatment (T30). Secondary outcomes were mortality at end of treatment (EoT), day survival at T30, and acquisition of multidrug-resistant bacteria during hospitalization in intensive care unit. Eighty cases of VAP were included and devised into two groups: No-TMP-SMX (31/80; 39%) and TMP-SMX (49/80; 61%). Univariate analysis showed no significant differences were found when the TMP-SMX group was compared with the No-TMP-SMX group, except for frequency of male gender (p = 0.025). No significant statistical correlations between mortality at T30 and individual factors were detected by the multivariate model. No cases of either severe allergy or Clostridium difficile disease were reported in the TMP-SMX and No-TMP-SMX groups. TMP-SMX treatment was not associated with higher mortality at EoT and T30 in comparison with the No-TMP-SMX group. TMP-SMX had a good safety profile, in terms of ecology (acquisition of MDR bacteria and Clostridium difficile disease) and clinical management (no allergy events).

Treatment of severe skin and soft tissue infections: a review

PURPOSE OF REVIEW

To review the salient features of the management of severe skin and soft tissue infections (SSTIs), including toxic shock syndrome, myonecrosis/gas gangrene, and necrotizing fasciitis.

RECENT FINDINGS

For severe SSTIs, intensive care, source control, and broad-spectrum antimicrobials are required for the initial phase of illness. There is an increasing focus on the utility of rapid diagnostic tests to help in selection and de-escalation of antimicrobials for SSTIs. In addition, clinical prediction scores have shown promise in helping predict patients who do not require antimicrobials directed against methicillin-resistant Staphylococcus aureus. Immune status has been shown to be important in clinical outcomes of some, but not all types of SSTIs. The debate for benefits of intravenous immunoglobulin continues to be waged in the recent literature.

SUMMARY

Severe SSTIs are common and their management complex due to regional variation in predominant pathogens and antimicrobial resistance patterns, as well variations in host immune responses. Unique aspects of care for severe SSTIs are discussed including the role of surgical consultation and source control. The unique features of SSTIs in immunocompromised hosts are also described.

Infectious Diseases Consultation Reduces 30-Day and 1-Year All-Cause Mortality for Multidrug-Resistant Organism Infections

Background

Multidrug-resistant organism (MDRO) infections are associated with high mortality and readmission rates. Infectious diseases (ID) consultation improves clinical outcomes for drug-resistant Staphylococcus aureus bloodstream infections. Our goal was to determine the association between ID consultation and mortality following various MDRO infections.

Methods

This study was conducted with a retrospective cohort (January 1, 2006–October 1, 2015) at an academic tertiary referral center. We identified patients with MDROs in a sterile site or bronchoalveolar lavage/bronchial wash culture. Mortality and readmissions within 1 year of index culture were identified, and the association of ID consultation with these outcomes was determined using Cox proportional hazards models with inverse weighting by the propensity score for ID consultation.

Results

A total of 4214 patients with MDRO infections were identified. ID consultation was significantly associated with reductions in 30-day and 1-year mortality for resistant S. aureus (hazard ratio [HR], 0.48; 95% confidence interval [CI], 0.36–0.63; and HR, 0.73, 95% CI, 0.61–0.86) and Enterobacteriaceae (HR, 0.41; 95% CI, 0.27–0.64; and HR, 0.74; 95% CI, 0.59–0.94), and 30-day mortality for polymicrobial infections (HR, 0.51; 95% CI, 0.31–0.86) but not Acinetobacter or Pseudomonas. For resistant Enterococcus, ID consultation was marginally associated with decreased 30-day mortality (HR, 0.81; 95% CI, 0.62–1.06). ID consultation was associated with reduced 30-day readmission for resistant Enterobacteriaceae.

Conclusions

ID consultation was associated with significant reductions in 30-day and 1-year mortality for resistant S. aureus and Enterobacteriaceae, and 30-day mortality for polymicrobial infections. There was no association between ID consultation and mortality for patients with resistant Pseudomonas, Acinetobacter, or Enterococcus, possibly due to small sample sizes. Our results suggest that ID consultation may be beneficial for patients with some MDRO infections.

When Good Bugs Go Bad: Epidemiology and Antimicrobial Resistance Profiles of Corynebacterium striatum, an Emerging Multidrug-Resistant, Opportunistic Pathogen

Infections with Corynebacterium striatum have been described in the literature over the last 2 decades, with the majority being bacteremia, central line infections, and occasionally, endocarditis. In recent years, the frequency of C. striatum infections appears to be increasing; a factor likely contributing to this is the increased ease and accuracy of the identification of Corynebacterium spp., including C. striatum, from clinical cultures. The objective of this study was to retrospectively characterize C. striatum isolates recovered from specimens submitted as part of routine patient care at a 1,250-bed, tertiary-care academic medical center. Multiple strain types were recovered, as demonstrated by repetitive-sequence-based PCR. Most of the strains of C. striatum characterized were resistant to antimicrobials commonly used to treat Gram-positive organisms, such as penicillin, ceftriaxone, meropenem, clindamycin, and tetracycline. The MIC₅₀ for ceftaroline was >32 μg/ml. Although there are no interpretive criteria for susceptibility with telavancin, it appeared to have potent in vitro efficacy against this species, with MIC₅₀ and MIC₉₀ values of 0.064 and 0.125 μg/ml, respectively. Finally, as previously reported in case studies, we demonstrated rapid in vitro development of daptomycin resistance in 100% of the isolates tested (n = 50), indicating that caution should be exhibited when using daptomycin for the treatment of C. striatum infections. C. striatum is an emerging, multidrug-resistant pathogen that can be associated with a variety of infection types.

WalK(S221P), a naturally occurring mutation, confers vancomycin resistance in VISA strain XN108

Objectives

Vancomycin-intermediate Staphylococcus aureus (VISA) strains have spread globally. We previously isolated an ST239 VISA (XN108) with a vancomycin MIC of 12 mg/L. The mechanism for XN108 resistance to vancomycin was investigated in this study.

Methods

Genome comparison was performed to characterize mutations that might contribute to the XN108 resistance phenotype. The novel mutation WalK(S221P) was identified and investigated using allelic replacement experiments. Vancomycin susceptibilities, autolytic activities and morphologies of the strains were examined. Autophosphorylation activities of WalK and the WalK(S221P) mutant were determined in vitro with [λ- 32 P]ATP, and binding activity of WalK(S221P)-activated WalR to the promoter region of its target gene lytM was determined by electrophoretic mobility shift assay.

Results

Genome comparison revealed three mutations, GraS(T136I), RpoB(H481N) and WalK(S221P), which might be responsible for vancomycin resistance in XN108. The introduction of WalK(S221P) to the vancomycin-susceptible strain N315 increased its vancomycin MIC from 1.5 to 8 mg/L, whereas the allelic replacement of WalK(S221P) with the native N315 WalK allele in XN108 decreased its vancomycin MIC from 12 to 4 mg/L. The VISA strains have thickened cell walls and decreased autolysis, consistent with observed changes in the expression of genes involved in cell wall metabolism and virulence regulation. WalK(S221P) exhibited reduced autophosphorylation, which may lead to reduced phosphorylation of WalR. WalK(S221P)-phosphorylated WalR also exhibited a reduced capacity to bind to the lytM promoter.

Conclusions

The naturally occurring WalK(S221P) mutation plays a key role in vancomycin resistance in XN108.

Topical Antimicrobial Treatments Can Elicit Shifts to Resident Skin Bacterial Communities and Reduce Colonization by Staphylococcus aureus Competitors

The skin microbiome is a complex ecosystem with important implications for cutaneous health and disease. Topical antibiotics and antiseptics are often employed to preserve the balance of this population and inhibit colonization by more pathogenic bacteria. However, despite their widespread use, the impact of these interventions on broader microbial communities remains poorly understood. Here, we report the longitudinal effects of topical antibiotics and antiseptics on skin bacterial communities and their role in Staphylococcus aureus colonization resistance. In response to antibiotics, cutaneous populations exhibited an immediate shift in bacterial residents, an effect that persisted for multiple days posttreatment. By contrast, antiseptics elicited only minor changes to skin bacterial populations, with few changes to the underlying microbiota. While variable in scope, both antibiotics and antiseptics were found to decrease colonization by commensal Staphylococcus spp. by sequencing- and culture-based methods, an effect which was highly dependent on baseline levels of Staphylococcus Because Staphylococcus residents have been shown to compete with the skin pathogen S. aureus, we also tested whether treatment could influence S. aureus levels at the skin surface. We found that treated mice were more susceptible to exogenous association with S. aureus and that precolonization with the same Staphylococcus residents that were previously disrupted by treatment reduced S. aureus levels by over 100-fold. In all, the results of this study indicate that antimicrobial drugs can alter skin bacterial residents and that these alterations can have critical implications for cutaneous host defense.

Diagnosis and management of skin and soft tissue infections in the intensive care unit: a review

PURPOSE

To review the salient features of the diagnosis and management of the most common skin and soft tissue infections (SSTI). This review focuses on severe SSTIs that require care in an intensive care unit (ICU), including toxic shock syndrome, myonecrosis/gas gangrene, and necrotizing fasciitis.

METHODS

Guidelines, expert opinion, and local institutional policies were reviewed.

RESULTS

Severe SSTIs are common and their management complex due to regional variation in predominant pathogens and antimicrobial resistance patterns, as well as variations in host immune responses. Unique aspects of care for SSTIs in the ICU are discussed, including the role of prosthetic devices, risk factors for bacteremia, and the need for surgical consultation. SSTI mimetics, the role of dermatologic consultation, and the unique features of SSTIs in immunocompromised hosts are also described.

CONCLUSIONS

We provide recommendations for clinicians regarding optimal SSTI management in the ICU setting.