Empirical antibiotic therapy for difficult-to-treat Gram-negative infections: when, how, and how long?

Antimicrobial strategies of lower respiratory tract infections in immunocompromised patients based on metagenomic next-generation sequencing: a retrospective study

BACKGROUND

Immunocompromised patients with Lower Respiratory Tract Infections (LRTI) frequently encounter a diverse range of pathogenic infections, characterized by rapid disease progression and significant mortality rates due to reckless or excessive utilization of antibiotics. Therefore, it is crucial to promptly and accurately identify the causative microorganisms for pathogen diagnosis and clinical decision-making. The objective of this study is to evaluate the clinical applicability of metagenomic next-generation sequencing (mNGS) in the diagnosis and management of LRTI, as well as its impact on empirical antibacterial therapy for patients with varying immune statuses.

METHODS

We conducted a comparative analysis of positivity rate, detection accuracy, pathogen spectrum, duration of treatment (DOT), and antibiotic management in a cohort of 283 patients diagnosed with lower respiratory tract infections.

RESULTS

The positive detection rate was higher in mNGS compared to conventional culture in both immunocompetent group (89.92% vs. 28.57%, P < 0.001) and immunocompromised group (84.44% vs. 33.33%, P < 0.001). The antibiotic escalation in the immunocompromised group was more frequent than that in the immunocompetent group (49.00% vs. 31.00%, P = 0.018), but no difference was observed for antibiotic de-escalation (20.00% vs. 15.00%, P = 0.458).

CONCLUSIONS

The application of mNGS can significantly enhance the pathogen detection rate and optimize antimicrobial drug management in immunocompromised patients with LRTI.

Evaluation of the Microbiological Performance and Potential Clinical Impact of New Rapid Molecular Assays for the Diagnosis of Bloodstream Infections

Bloodstream infection (BSI) is a critical medical emergency associated with a high mortality rate. Rapid and accurate identification of the causative pathogen and the results of antimicrobial susceptibility testing are crucial for initiating appropriate antimicrobial therapy. The aim of this study was to evaluate the performance of a new rapid PCR Molecular Mouse System (MMS) for the identification of Gram-negative bacteria (GNB) and GNB resistance genes directly from a positive blood culture (BC). The validation of these rapid multiplex assays was carried out in a real hospital setting. A total of 80 BSI episodes were included in our study and the results were compared with culture-based methods. BC samples in which GNB had previously been detected microscopically and which originated from different hospital wards were analysed. The MMS GNB identification assay achieved a sensitivity of 98.7% and a specificity of 100% for the covered pathogens. In one BC sample, Klebsiella aerogenes was identified at the family level (Enterobacteriaceae) with MMS. However, in three polymicrobial samples, MMS identified bacteria that were not detected by culture-based methods (Klebsiella pneumoniae, K. aerogenes and Stenotrophomonas maltophilia). MMS also showed excellent overall performance in the detection of GNB resistance markers (100% sensitivity and 100% specificity). The type of extended-spectrum beta-lactamase (ESBL) resistance gene identified correctly with MMS was CTX-M-1/9 (n = 17/20), alone or in combination with SHV-type β-lactamase or with the different types of carbapenemase genes. MMS detected one carbapenemase gene of each type (KPC, NDM and OXA-23) and six OXA-48 genes. In addition, the colistin resistance gene mcr-1 was detected in one positive BC with Escherichia coli (E. coli). The time to result was significantly shorter for MMS than for routine culture methods. A retrospective analysis of the patients' medical records revealed that a change in empirical antimicrobial therapy would have been made in around half of the patients following the MMS results. These results support the use of MMS as a valuable complement to conventional culture methods for more rapid BSI diagnosis and adjustment of empirical therapy.

Clinical Outcomes of Acute Pyelonephritis in Type 2 Diabetes Mellitus

Background Diabetes mellitus (DM) is a prevalent predisposing factor for urinary tract infections (UTIs). Among hospitalized patients with acute pyelonephritis, UTIs are more common, severe, and associated with worse outcomes, particularly in those with type 2 DM. Pyelonephritis in DM patients is more frequently bilateral and linked to greater complications, with 90% of emphysematous pyelonephritis (EMPN) and cystitis cases occurring in diabetic individuals. Objective This study aims to evaluate the clinical and microbiological profiles, treatment outcomes, and complications of acute pyelonephritis in patients with type 2 DM. Methods A six-month prospective observational study was conducted from March 2016 to August 2016 at Stanley Medical College and Hospital, Chennai, India. A total of 102 hospitalized patients presenting with symptoms suggestive of acute pyelonephritis were included. Data were collected using a clinical questionnaire and analyzed using IBM SPSS Statistics for Windows, Version 20.0 (Released 2011; IBM Corp., Armonk, New York, United States). Patients received culture-sensitive antimicrobial therapy, percutaneous drainage, and renal replacement therapy as required. Results Out of 102 patients, 80 (78.4%) had non-emphysematous pyelonephritis (NEMPN), and 22 (21.6%) had EMPN. The mean age was 55.2±10.9 years, with a female predominance of 63 (78.4%) participants. Escherichia coli was the most common organism isolated in 70 (68.6%) cases. Renal dysfunction was present in 67 (65.7%) patients, with a higher prevalence in EMPN (22, 100%) compared to NEMPN (45, 56.3%) (p<0.001). Mortality was observed in three (3.9%) patients, and 25 (24.5%) developed de novo or progressive chronic kidney disease. Conclusion Early diagnosis and aggressive management of EMPN in type 2 DM patients improve outcomes. Acute pyelonephritis is predominantly observed in women, with fever and loin pain as the most common symptoms. Escherichia coli is the primary pathogen, and renal dysfunction is frequent but often reversible. Mortality is low with appropriate management.

Carbapenem or new β-lactam-β-lactamase inhibitors? An Italian survey supported by SITA, SIMIT and SIAARTI to identify the factors affecting empiric antimicrobial therapy choice in real-life clinical practice

While a tailored antibiotic treatment plan is often straightforward, what we often observe in daily clinical practice is a highly variable approach when defining empirical therapy. Specifically, a debate exists on preference to spare the new β-lactams and β-lactamase inhibitors (BL-BLIs) or to apply a carbapenem-sparing strategy first. To investigate, we designed a web survey aimed at investigating the variables considered relevant to empirically choosing one antibiotic over the other. Submitted to Italian infectious diseases and intensive care physicians through the support of Società Italiana di Malattie Infettive e Tropicali (SIMIT), Società Italiana di Terapia Antinfettiva (SITA) and Società Italiana Anestesia, Analgesia, Rianimazione e Terapia Intensiva (SIAARTI). We found that demographic characteristics were irrelevant when deciding for empirical therapy. Clinical and anamnestic data were most meaningful. Significantly considered were underlying comorbidities and previous exposure to antimicrobial treatments. History of third-generation cephalosporin-resistant, carbapenem-resistant and/or metallo-β-lactamase-producing Enterobacterales rectal colonisation and/or infection were considered the most relevant by most physicians. Unexpectedly, clinicians considered less the source of infection. These results prompt the need of straightforward methods to retrieve medical histories and the magnitude of rectal colonisation data, often not routinely obtained.

State of the Management of Infections Caused by Multidrug-Resistant Gram-Negative Organisms

In the past decade, the prevalence of multidrug-resistant gram-negative (MDR-GN) bacterial infections has increased significantly, leading to higher rates of morbidity and mortality. Treating these infections poses numerous challenges, particularly when selecting appropriate empiric therapy for critically ill patients for whom the margin for error is low. Fortunately, the availability of new therapies has improved the treatment landscape, offering safer and more effective options. However, there remains a need to establish and implement optimal clinical and therapeutic approaches for managing these infections. Here, we review strategies for identifying patients at risk for MDR-GN infections, propose a framework for the choice of empiric and definitive treatment, and explore effective multidisciplinary approaches to managing patients in the hospital while ensuring a safe transition to outpatient settings.

Effectors of the Type VI Secretion System Have the Potential to Be Modified into Antimicrobial Peptides

The use of antibiotics has led to the emergence of multidrug-resistant (MDR) bacteria, and there is an urgent need to find alternative treatments to alleviate this pressure. The type VI secretion system (T6SS) is a protein delivery system present in bacterial cells that secretes effectors that participate in bacterial virulence. Given the potential for the transformation of these effectors into antimicrobial peptides (AMPs), we designed T6SS effectors into AMPs that have a membrane-disrupting effect. These effectors kill bacteria by altering the membrane potential and increasing the intracellular reactive oxygen species (ROS) content. Moreover, AMPs also have a significant therapeutic effect both in vivo and in vitro. This finding suggests that it is possible to modify bacterial components of bacteria themselves to create compounds that fight bacteria. IMPORTANCE This study first identified and modified the T6SS effector into positively charged alpha-helical peptides. These peptides have good antibacterial and bactericidal effects on G+ bacteria and G- bacteria. This study broadens the source of AMPs and makes T6SS effectors more useful.

An overview of gram-negative bacteria with difficult-to-treat resistance: definition, prevalence, and treatment options

INTRODUCTION

Difficult-to-treat resistance (DTR) is a newly proposed resistance phenotype characterized by resistance to all first-line drugs. The emergence of DTR as a new resistance phenotype has significant implications for clinical practice. This new concept has the potential to be widely used instead of traditional phenotypes.

AREAS COVERED

This study carried out a detailed analysis about the definition, application, and evolution of various resistance phenotypes. We collected all the research articles on Gram-negative bacteria with difficult-to-treat resistance (GNB-DTR), analyzed the DTR in each region and each bacterial species. The advantages and doubts of DTR, the dilemma of GNB-DTR infections and the potential therapeutic strategies are summarized in the review.

EXPERT OPINION

Available studies show that the prevalence of GNB-DTR is not optimistic. Unlike traditional resistance phenotypes, DTR is more closely aligned with the clinical treatment perspective and can help with the prompt selection of an appropriate treatment plan. Currently, potential treatment options for GNB-DTR include a number of second-line drugs and novel antibiotics. However, the definition of first-line drugs is inherently dynamic. Therefore, the DTR concept based on first-line drugs needs to be continuously updated and refined, considering the emergence of new antibiotics, resistance characteristics, and pathogen prevalence in different regions.