Epidemiology, Mechanisms of Resistance and Treatment Algorithm for Infections Due to Carbapenem-Resistant Gram-Negative Bacteria: An Expert Panel Opinion

Screening of antimicrobial activity in venom: Exploring key parameters

The escalating challenge of antibiotic resistance significantly threatens global health, underscoring the critical need for new antimicrobial agents. Venoms, increasingly recognized as reservoirs of bioactive compounds with diverse pharmacological effects, have been the focus of recent research. This work evaluates the use of various screening methodologies in assessing the antimicrobial activities of 185 venoms against some gram positive and gram negative bacteria, including E. coli ATCC 8739, B. subtilis ATCC 6633, P. aeruginosa ATCC 9027, and S. aureus ATCC 6538P species and explores the influence of settings on the findings. Furthermore, the research explored the possibility of purifying antimicrobial molecules from venoms through HPLC. Several fractions demonstrated antimicrobial activity against the tested strains. Our results reveal that the measured antimicrobial efficacy of venoms varies according to:i) venom concentration, ii) the detection method, including microdilution and radial diffusion assays, and iii) the choice of culture medium, specifically LB or MH. This strategy has allowed us, for the first time, to identify antimicrobial activity in: i) Bitis arietans venom against P. aeruginosa ATCC 9027, ii) Naja nubiae and Bothrops lanceolatus against B. subtilis ATCC 6633, P. aeruginosa ATCC 9027, and S. aureus ATCC 6538P, and iii) Hadogenes zuluanus, Mesobuthus caucasicus, Nebo hierichonticus, Opistophthalmus wahlbergii scorpions, and Mylabris quadripunctata beetles against S. aureus ATCC 6538P. These findings highlight venoms potential as effective antimicrobial resources and improve our understanding of key factors critical for an accurate detection of venoms antimicrobial properties.

Treatment of Carbapenem-Resistant Acinetobacter baumannii in Real Life (T-ACI): A Prospective Single-Center Observational Study

Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) poses significant challenges in healthcare due to its multidrug resistance and high mortality rates among critically ill patients. Results: We enrolled 45 patients. Cefiderocol was administered to 40% of patients, often (38.8%) in combination with other antibiotics. Colistin was administered to 60% of patients and always in combination, mostly with ampicillin-sulbactam. The overall ECS and OCS rates were 77.8% and 66.7%, respectively. Patients treated with an initial cefiderocol-based regimen showed a higher rate of ECS compared with patients initially treated with colistin-based regimens (100% vs. 63%, p < 0.05). Patients treated with cefiderocol alone showed a higher rate of ECS compared with patients treated with cefiderocol-based regimens (100% vs. 70.6%, p < 0.05). No differences in OCS rates were recorded depending on the treatment received. Additionally, cefiderocol regimens were associated with fewer ADRs compared to colistin-based treatment. Methods: This prospective observational study enrolled patients with CRAB infections from January 2022 to August 2023. Patients were treated with cefiderocol-based or colistin-based regimens and were monitored for 28 days to assess early clinical success (ECS), overall clinical success (OCS) and adverse drug reactions (ADRs). Conclusions: This study highlights the potential advantages of cefiderocol, even used as a monotherapy, in treating CRAB, especially when early clinical and laboratory response was assessed. This research contributes to the ongoing discussion on the most effective and safe treatments for combating CRAB infections, supporting the use of cefiderocol in clinical practice.

Probiotic-Loaded Bacterial Cellulose as an Alternative to Combat Carbapenem-Resistant Bacterial Infections

Background: Carbapenems are one of the mainstays of treatment for antibiotic-resistant bacteria (ARB). This has made the rise of carbapenem-resistant bacteria a threat to global health. In fact, the World Health Organization (WHO) has identified carbapenem-resistant bacteria as critical pathogens, and the development of novel antibacterials capable of combating infections caused by these bacteria is a priority. Objective: With the aim of finding new alternatives to fight against ARB and especially against carbapenem-resistant bacteria, we have developed a series of living materials formed by incorporating the probiotics Lactobacillus plantarum (Lp), Lactobacillus fermentum (Lf), and a mixture of both (L. plantarum+L. fermentum) into bacterial cellulose (BC). Results: These probiotic-loaded bacterial celluloses inhibited the proliferation of three ARB, including two carbapenem-resistant enterobacteria (CRE), identified as Klebsiella pneumoniae and Enterobacter cloacae, and a carbapenem-resistant Pseudomonas aeruginosa. Interestingly, while the probiotics L. plantarum, L. fermentum, and the mixture of both were found to be inactive against these ARB, they became active once incorporated into BC. Conclusions: The increase in activity is due to the known effect that cells increase their activity once incorporated into a suitable matrix, forming a living material. For the same reasons, the probiotics in the living materials BC-L. plantarum, BC-L. fermentum, and BC-L. plantarum+L. fermentum showed increased stability, allowing them to be stored with bacterial activity for long periods of time (two months).

Pharmacokinetic parameters of CAZ-AVI in the normal lung and in models of pneumonia: lessons for treatment optimization in critical care

The spread of multidrug-resistant Gram-negative bacterial infections is a significant issue for worldwide public health. Gram-negative organisms regularly develop resistance to antibiotics, especially to β-lactam antimicrobials, which can drastically restrict the number of therapies. A third-generation cephalosporin and the non-β-lactam β-lactamase inhibitor avibactam, which exhibits broad-spectrum β-lactamase inhibition in vitro, are combined to form ceftazidime-avibactam (CAZ-AVI). In this narrative review, we summarize data on pharmacokinetic (PK) parameters for CAZ-AVI in both animal and human models of pneumonia, as well as in healthy individuals. We assessed current literature performing an extensive search of the literature, using as search words 'CAZ-AVI', 'pharmacokinetics', 'pneumonia', 'lung', and 'epithelial lining fluid'. Overall, lung exposure studies of CAZ-AVI revealed that the epithelial lining fluid penetration ranges between 30% and 35% of plasma concentration. Despite the fair lung penetration of CAZ-AVI, this antimicrobial agent has a pivotal role in managing patients with multi-drug resistant Gram-negative pneumonia, however further studies are needed to better assess its PK profile.

Comparison of cefiderocol and colistin-based regimens for the treatment of severe infections caused by carbapenem-resistant Acinetobacter baumannii: a systematic review with meta-analysis and trial sequential analysis

BACKGROUND

There are multiple antibiotic regimens for the treatment of carbapenem-resistant Acinetobacter baumannii (CRAB) in clinical practice. We conducted this meta-analysis to compare the efficacy and safety of cefiderocol-based regimens and colistin-based regimens in the treatment of CRAB infections.

METHODS

Two authors independently searched the PubMed, Web of Science, Embase, and Cochrane databases from their establishment to April 15, 2024, to search for randomized controlled trials (RCTs) or cohort studies, and compared the clinical efficacy and safety of cefiderocol-based regimens and colistin-based regimens in the treatment of CRAB infections. The Newcastle Ottawa Scale (NOS) checklist was used to evaluate the quality of the included studies. The primary outcome was all-cause mortality, and subgroup analysis was conducted on the basis of the site of infection and the risk of bias in the studies. Trial sequential analysis (TSA) was then conducted.

RESULTS

Six observational studies were included, with 251 cases in the cefiderocol-based group and 372 cases in the colistin-based group. Compared to the colistin-based group, the cefiderocol-based group had lower all-cause mortality (RR = 0.71, 95% CI: 0.54-0.92, P = 0.01) and 30-day mortality (RR = 0.64, 95% CI: 0.43-0.95, P = 0.03). However, for the 14-day and 28-day mortality rates, there was no statistically significant difference between two groups. According to the subgroup analysis, among patients with bloodstream infection (BSI), the cefiderocol-based group had lower all-cause mortality, but it did not reduce the mortality of ventilator-associated pneumonia (VAP) patients. The result of TSA showed that our conclusions are reliable. There was no significant statistical difference in the microbiological cure rate, clinical cure rate, or duration of hospitalization. In addition, the cefiderocol-based group did not have an increased incidence of acute kidney injury (AKI).

CONCLUSIONS

Compared with the colistin-based regimens, the cefiderocol-based regimens were significantly associated with a lower risk of mortality in CRAB-infected patients, especially for patients with BSI. However, they did not show any advantages in terms of the clinical cure rate or microbiological cure rate, nor did they reduce the incidence of AKI.

PROSPERO REGISTRATION NUMBER

CRD42023487213.

Genomic Insights into Vietnamese Extended-Spectrum β-Lactamase-9-Producing Extensively Drug-Resistant Pseudomonas aeruginosa Isolates Belonging to the High-Risk Clone ST357 Obtained from Bulgarian Intensive Care Unit Patients

Extensively drug-resistant P. aeruginosa (XDR-PA) has been highlighted as a serious public health threat. The present study aimed to explore the genomic characteristics of two Vietnamese extended-spectrum β-lactamase-9 (VEB-9)-producing XDR-PA isolates from Bulgaria in comparison to all blaVEB-9-positive strains with available genomes. The isolates designated Pae51 and Pae52 were obtained from tracheobronchial aspirates of intensive care unit (ICU) patients. Antimicrobial susceptibility testing, whole-genome sequencing, RT-qPCR, and phylogenomic analysis were performed. Pae51 and Pae52 were resistant to most antipseudomonal β-lactams including carbapenems, aminoglycosides, and fluoroquinolones but remained susceptible to colistin and cefiderocol. Numerous resistance determinants were detected: blaVEB-9, blaPDC-3, blaOXA-10, blaOXA-50, aac(6')-II, ant(2″)-Ia, ant(3″)-IIa, aph(3')-IIb, cprP, catB7, dfrB2, sul1, fosA, and tet(A). Both isolates carried complex integrons with blaVEB-9 and tet(A) embedded next to the conservative 3' end sequences. A variety of virulence factors were also identified, including the type III secretion system exotoxin U. Pae51 and Pae52 differed by only four SNPs and belonged to the high-risk clone ST357. To our knowledge, this is the first report of blaVEB-9-positive XDR-PA isolates in Bulgaria presenting a detailed genomic analysis. The development of novel antimicrobial strategies for such pathogens should be an essential part of infection control stewardship practices in ICU wards.

Analyzing Pre-operative Hospital Stay and Incidence of Hospital Acquired Infection: A Retrospective Study

Background and objectives

Healthcare-associated infections (HCAIs) pose a significant challenge, impacting patient safety and treatment effectiveness. This retrospective study investigates the correlation between pre-operative hospital stays and HCAIs in ICU cardiac surgery patients.

Materials and methods

Medical records of 35 patients who died post-cardiac surgery in the ICU were analyzed, focusing on the duration of pre-operative hospitalization.

Results

Prolonged pre-operative stays strongly correlate (r = 0.993) with increased HCAIs, indicating a critical risk factor.

Conclusions

The duration of pre-operative hospital stays is pivotal in HCAI risk. Prospective multicenter studies are needed for validation, which is crucial for enhancing patient safety and treatment efficacy.

A retrospective analysis of carbapenem-resistant Acinetobacter baumannii infections in critically ill patients: Experience at a tertiary-care teaching hospital ICU

Background

Acinetobacter baumannii is a clinically significant pathogen with a high incidence of multidrug resistance that is associated with life-threatening nosocomial infections. Here, we aimed to provide an insight into the clinical characteristics and outcomes of a unique group of A. baumannii infections in which the isolates were resistant to carbapenems and most other antibiotic groups in a tertiary-care intensive care unit (ICU).

Methods

We performed a retrospective observational study in which records of patients hospitalized in the ICU between June 1, 2021 and June 1, 2023 were reviewed. We checked the clinical, laboratory, and microbiological records of all adult patients who had carbapenem-resistant A. baumannii (CRAB) infections. Prior antibiotic treatments and definitive antibiotic treatments after culture positivity and susceptibility test results were recorded. C-reactive protein (CRP) and procalcitonin levels and leukocyte counts were noted. Length of ICU stay and 30-day mortality were defined as the outcome parameters.

Results

During the study period, 57 patients were diagnosed with CRAB infections. The respiratory tract was the leading infection site (80.7%). In non-survivors, bloodstream infections (21.9% vs. 4.0% P=0.05) and colistin-resistant (col-R) CRAB infections (43.8% vs. 24.0%, P=0.12) were more common than in survivors, but these parameters were not statistically significant. The length of ICU stay was not different between survivors and non-survivors. Overall, the rate of col-R among CRAB clinical isolates was 35.1%. The 30-day mortality in all patients with CRAB infection was 56.1%. Mortality in col-R CRAB and colistin-susceptible (col-S) CRAB infections was 70.0% and 48.6%, respectively (P=0.12). Prior carbapenem use was 56.1%. Prior colistin use before col-R and col-S CRAB infections was not significant (35.0% vs. 27.0%, P=0.53).

Conclusions

Our study provides real-world data on highly resistant A. baumannii infections and shares the characteristics of infections with such resistant strains. Unfortunately, carbapenem resistance in A. baumannii is a challenge for intensive care specialists who are faced with few treatment options, and colistin resistance further complicates the problem.

Cefiderocol either in monotherapy or combination versus best available therapy in the treatment of carbapenem-resistant Acinetobacter baumannii infections: A systematic review and meta-analysis

BACKGROUND

The best treatment for carbapenem-resistant Acinetobacter baumannii (CRAB) infections is still a matter of debate.

OBJECTIVES

To describe the outcomes of patients treated with cefiderocol for CRAB infections, and to compare the efficacy of cefiderocol versus best available therapy (BAT).

DATA SOURCES

We searched MEDLINE, the Cochrane Library and EMBASE to screen original reports published up to September 2023.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials (RCTs) and observational studies investigating 30-day mortality, clinical failure, microbiological failure or rate of adverse drug reactions of patients treated with cefiderocol or BAT.

PARTICIPANTS

Patients with infections due to CRAB.

INTERVENTIONS

Cefiderocol in monotherapy or in combination with other potentially active agents or BAT.

ASSESSMENT OF RISK OF BIAS

We used the Cochrane Risk of Bias Tool for RCTs, and the Newcastle Ottawa scale for observational studies.

METHODS OF DATA SYNTHESIS

We conducted a meta-analysis pooling risk ratios (RRs) through random effect models.

RESULTS

We screened 801 original reports, and 18 studies (2 RCTs, 13 cohort studies and 3 case-series) were included in the analysis, for a total 733 patients treated with cefiderocol, and 473 receiving the BAT. Among patients receiving cefiderocol, the 30-day mortality rate was 42% (95% CI 38-47%), the rate of microbiological failure 48% (95% CI 31-65%), the clinical failure rate 43% (95% CI 32-55%), and the rate of ADRs was 3% (95% CI 1-6%). A lower mortality rate was observed among patients receiving cefiderocol monotherapy as compared to those treated with combination regimens (RR: 0.64; 95% CI: 0.43-0.94, p = 0.024). We found a significantly lower mortality rate (RR: 0.74; 95% CI: 0.57-0.95, p = 0.02) and a lower rate of ADRs (RR: 0.28; 95% CI: 0.09-0.91, p = 0.03) in the group treated with cefiderocol as compared to BAT. No difference was observed in microbiological and clinical failure rate.

CONCLUSIONS

Our data strengthen the efficacy and safety profile of cefiderocol in CRAB infections.

Zein nanoparticles containing ceftazidime and tobramycin: antibacterial activity against Gram-negative bacteria

Aims: This work describes the encapsulation of ceftazidime and tobramycin in zein nanoparticles (ZNPs) and the characterization of their antibacterial and antibiofilm activities against Gram-negative bacteria. Materials & methods: ZNPs were synthesized by nanoprecipitation. Cytotoxicity was assessed by MTT assay and antibacterial and antibiofilm assays were performed by broth microdilution and violet crystal techniques. Results: ZNPs containing ceftazidime (CAZ-ZNPs) and tobramycin (TOB-ZNPs) showed drug encapsulation and thermal stability. Encapsulation of the drugs reduced their cytotoxicity 9-25-fold. Antibacterial activity, inhibition and eradication of biofilm by CAZ-ZNPs and TOB-ZNPs were observed. There was potentiation when CAZ-ZNPs and TOB-ZNPs were combined. Conclusion: CAZ-ZNPs and TOB-ZNPs present ideal physical characteristics for in vivo studies of antibacterial and antibiofilm activities.

Antibiotic resistance genes prediction via whole genome sequence analysis of Stenotrophomonas maltophilia

BACKGROUND

Stenotrophomonas maltophilia (S. maltophilia) is the first dominant ubiquitous bacterial species identified from the genus Stenotrophomonas in 1943 from a human source. S. maltophilia clinical strains are resistance to several therapies, this study is designed to investigate the whole genome sequence and antimicrobial resistance genes prediction in Stenotrophomonas maltophilia (S. maltophilia) SARC-5 and SARC-6 strains, isolated from the nasopharyngeal samples of an immunocompromised patient.

METHODS

These bacterial strains were obtained from Pakistan Institute of Medical Sciences (PIMS) Hospital, Pakistan. The bacterial genome was sequenced using a whole-genome shotgun via a commercial service that used an NGS (Next Generation Sequencing) technology called as Illumina Hiseq 2000 system for genomic sequencing. Moreover, detailed in-silico analyses were done to predict the presence of antibiotic resistance genes in S. maltophilia.

RESULTS

Results showed that S. maltophilia is a rare gram negative, rod-shaped, non sporulating bacteria. The genome assembly results in 24 contigs (>500 bp) having a size of 4668,850 bp with 65.8% GC contents. Phylogenetic analysis showed that SARC-5 and SARC-6 were closely related to S. maltophilia B111, S. maltophilia BAB-5317, S. maltophilia AHL, S. maltophilia BAB-5307, S. maltophilia RD-AZPVI_04, S. maltophilia JFZ2, S. maltophilia RD_MAAMIB_06 and lastly with S. maltophilia sp ROi7. Moreover, the whole genome sequence analysis of both SARC-5 and SARC-6 revealed the presence of four resistance genes adeF, qacG, adeF, and smeR.

CONCLUSION

Our study confirmed that S. maltophilia SARC-5 and SARC-6 are one of the leading causes of nosocomial infection which carry multiple antibiotic resistance genes.

Carbapenem resistant Enterobacterales in the United Arab Emirates: a retrospective analysis from 2010 to 2021

Background

Carbapenem-resistant Enterobacterales (CRE) are spreading in the United Arab Emirates (UAE) where their dissemination is facilitated by international travel, trade, and tourism. The objective of this study is to describe the longitudinal changes of CRE as reported by the national AMR surveillance system of the UAE.

Methods

In this study, we retrospectively describe CRE isolated from 317 surveillance sites, including 87 hospitals and 230 centers/clinics from 2010 to 2021. The associated clinical, demographic, and microbiological characteristics are presented by relying on the UAE national AMR surveillance program. Data was analyzed using WHONET microbiology laboratory database software (http://www.whonet.org).

Results

A total of 14,593 carbapenem resistant Enterobacterales were analyzed, of which 48.1% were carbapenem resistant Klebsiella pneumoniae (CRKp), 25.1% carbapenem resistant Escherichia coli (CREc), and 26.8% represented 72 other carbapenem resistant species. Carbapenem resistant strains were mostly associated with adults and isolated from urine samples (36.9% of CRKp and 66.6% of CREc) followed by respiratory samples (26.95% for CRKp) and soft tissue samples (19.5% for CRKp). Over the studied period carbapenem resistance rates remained high, especially in K. pneumoniae, and in 2021 were equivalent to 67.6% for imipenem, 76.2% for meropenem, and 91.6% for ertapenem. Nevertheless, there was a statistically significant decreasing trend for imipenem and meropenem resistance in Klebsiella species (p < 0.01) while the decrease in ertapenem resistance was non-significant. Concerning E. coli, there was a statistically significant decreasing trend for meropenem and imipenem resistance over the 12 years, while ertapenem resistance increased significantly with 83.8% of E. coli exhibiting ertapenem resistance in 2021. Resistance rates to ceftazidime and cefotaxime remained higher than 90% (in 2021) for CRKp and cefotaxime rates increased to 90.5% in 2021 for CREc. Starting 2014, resistance to colistin and tigecycline was observed in carbapenem resistant Enterobacterales. CRE were associated with a higher mortality (RR: 6.3), admission to ICU (RR 3.9), and increased length of stay (LOS; 10 excess inpatient days per CRE case).

Conclusion

This study supports the need to monitor CRE in the UAE and draws attention to the significant increase of ertapenem resistance in E. coli. Future surveillance analysis should include a genetic description of carbapenem resistance to provide new strategies.

Emerging infections in vulnerable hosts: Stenotrophomonas maltophilia and Elizabethkingia anophelis

PURPOSE OF REVIEW

This systematic review aimed to explore the recent trends in the epidemiology, risk factors, and antimicrobial susceptibility of two emerging opportunistic pathogens, Stenotrophomonas maltophilia and Elizabethkingia anophelis .

RECENT FINDINGS

Since 2020, numerous outbreaks of S. maltophilia and E. anophelis have been reported worldwide. Most of these outbreaks have been associated with healthcare facilities, although one outbreak caused by E. anophelis in France was considered a community-associated infection. In terms of antimicrobial susceptibility, trimethoprim/sulfamethoxazole (TMP-SMZ), levofloxacin, and minocycline have exhibited good efficacy against S. maltophilia . Additionally, cefiderocol and a combination of aztreonam and avibactam have shown promising results in in vitro susceptibility testing. For E. anophelis , there is currently no consensus on the optimal treatment. Although some studies have reported good efficacy with rifampin, TMP-SMZ, piperacillin/tazobactam, and cefoperazone/sulbactam, minocycline had the most favourable in vitro susceptibility rates. Cefiderocol may serve as an alternative due to its low minimum inhibitory concentration (MIC) against E. anophelis . The role of vancomycin in treatment is still uncertain, although several successful cases with vancomycin treatment, even with high MIC values, have been reported.

SUMMARY

Immunocompromised patients are particularly vulnerable to infections caused by S. maltophilia and E. anophelis , but the optimal treatment strategy remains inconclusive. Further research is necessary to determine the most effective use of conventional and novel antimicrobial agents in combatting these multidrug-resistant pathogens.

Outcome of patients with carbapenem-resistant Acinetobacter baumannii infections treated with cefiderocol: A multicenter observational study

BACKGROUND

No clear evidence supports the use of cefiderocol as first line treatment in A. baumannii infections.

METHODS

We conducted an observational retrospective/prospective multicenter study including all patients> 18 years with carbapenem-resistant A. baumannii (CRAB) infections treated with cefiderocol, from June 12021 to October 30 2022. Primary endpoint was 30-day mortality, secondary end-points the clinical and microbiological response at 7 days and at the end of treatment. Furthermore, we compared the clinical and microbiological outcomes among patients who received cefiderocol in monotherapy or in combination.

RESULTS

Thirty-eight patients with forty episodes of infection were included [mean age 65 years (SD+16.3), 75% males, 90% with hospital-acquired infections and 70% showing sepsis or septic shock]. The most common infections included unknown source or catheter-related bacteremia (45%) and pneumonia (40%). We observed at 7 days and at the end of therapy a rate of microbiological failure of 20% and 10%, respectively, and of clinical failure of 47.5% and 32.5%, respectively; the 30-day mortality rate was 47.5%. At multivariate analysis clinical failure at 7 days of treatment was the only independent predictor of 30-day mortality. Comparing monotherapy (used in 72.5%) vs. combination therapy (used in 27.5%), no differences were observed in mortality (51.7 vs 45.5%) and clinical (41.4 vs 63.7%) or microbiological failure (24.1 vs 9.1%).

CONCLUSIONS

The findings of this study reinforce the effectiveness of cefiderocol in CRAB infections, also as monotherapy. However, prospective multicenter studies with larger sample sizes and a control group treated with standard of care are needed to identify the best treatment for CRAB infections.

Stenotrophomonas maltophilia Infections: A Systematic Review and Meta-Analysis of Comparative Efficacy of Available Treatments, with Critical Assessment of Novel Therapeutic Options

Stenotrophomonas maltophilia (SM) represents a challenging pathogen due to its resistance profile. A systematic review of the available evidence was conducted to evaluate the best treatment of SM infections to date, focusing on trimethoprim/sulfamethoxazole (TMP/SMX), fluoroquinolones (FQs), and tetracycline derivatives (TDs).

MATERIALS

PubMed/MEDLINE and Embase were searched from inception to 30 November 2022. The primary outcome was all-cause mortality. Secondary outcomes included clinical failure, adverse events, and length of stay. A random effects meta-analysis was performed. This study was registered with PROSPERO (CRD42022321893).

RESULTS

Twenty-four studies, all retrospective, were included. A significant difference in terms of overall mortality was observed when comparing as a monotherapy TMP/SMX versus FQs (odds ratio (OR) 1.46, 95% confidence interval (CI) 1.15-1.86, I2 = 33%; 11 studies, 2407 patients). The prediction interval (PI) did not touch the no effect line (1.06-1.93), but the results were not robust for the unmeasured confounding (E-value for point estimate of 1.71). When comparing TMP/SMX with TDs, the former showed an association with higher mortality but not significant and with a wide PI (OR 1.95, 95% CI 0.79-4.82, PI 0.01-685.99, I2 = 0%; 3 studies, 346 patients). Monotherapies in general exerted a protective effect against death opposed to the combination regimens but were not significant (OR 0.71, 95% CI 0.41-1.22, PI 0.16-3.08, I2 = 0%; 4 studies, 438 patients).

CONCLUSIONS

Against SM infections, FQs and, possibly, TDs seem to be reasonable alternative choices to TMP/SMX. Data from clinical trials are urgently needed to better inform therapeutic choices in this setting by also taking into account newer agents.

Source Control of Gram-Negative Bacteria Using Self-Disinfecting Sinks in a Swedish Burn Centre

Several retrospective studies have identified hospital sinks as reservoirs of Gram-negative bacteria. The aim of this study was to prospectively investigate the bacterial transmission from sinks to patients and if self-disinfecting sinks could reduce this risk. Samples were collected weekly from sinks (self-disinfecting, treated with boiling water, not treated) and patients in the Burn Centre at Linköping University Hospital, Sweden. The antibiotic susceptibility of Gram-negative isolates was tested, and eight randomly chosen patient isolates and their connected sink isolates were subjected to whole genome sequencing (WGS). Of 489 sink samples, 232 (47%) showed growth. The most frequent findings were Stenotrophomonas maltophilia (n = 130), Pseudomonas aeruginosa (n = 128), and Acinetobacter spp. (n = 55). Bacterial growth was observed in 20% of the samplings from the self-disinfecting sinks and in 57% from the sinks treated with boiling water (p = 0.0029). WGS recognized one transmission of Escherichia coli sampled from an untreated sink to a patient admitted to the same room. In conclusion, the results showed that sinks can serve as reservoirs of Gram-negative bacteria and that self-disinfecting sinks can reduce the transmission risk. Installing self-disinfecting sinks in intensive care units is an important measure in preventing nosocomial infection among critically ill patients.

Evidence-Based Treatment of Pseudomonas aeruginosa Infections: A Critical Reappraisal

Multidrug-resistant (MDR)/extensively drug-resistant (XDR) Pseudomonas aeruginosa is emerging as a major threat related to adverse patient outcomes. The goal of this review is to describe evidence-based empiric and targeted treatment regimens that can be exploited when dealing with suspected or confirmed infections due to MDR/XDR P. aeruginosa. P. aeruginosa has inherent resistance to many drug classes, the capacity to form biofilms, and most importantly, the ability to quickly acquire resistance to ongoing treatments. Based on the presence of risk factors for MDR/XDR infections and local epidemiology, where large proportions of strains are resistant to classic beta-lactams, the recommended empirical treatment for suspected P. aeruginosa infections is based on ceftolozane-tazobactam or ceftazidime-avibactam. Where local epidemiology indicates low rates of MDR/XDR and there are no risk factors, a third or fourth generation cephalosporin can be used in the context of a "carbapenem-sparing" strategy. Whenever feasible, antibiotic de-escalation is recommended after antimicrobial susceptibility tests suggest that it is appropriate, and de-escalation is based on different resistance mechanisms. Cefiderocol and imipenem-cilastatin-relebactam withstand most resistance mechanisms and may remain active in cases with resistance to other new antibiotics. Confronting the growing threat of MDR/XDR P. aeruginosa, treatment choices should be wise, sparing newer antibiotics when dealing with a suspected/confirmed susceptible P. aeruginosa strain and choosing the right option for MDR/XDR P. aeruginosa based on specific types and resistance mechanisms.

Combination Therapy versus Monotherapy in the Treatment of Stenotrophomonas maltophilia Infections: A Systematic Review and Meta-Analysis

Stenotrophomonas maltophilia is a multidrug-resistant bacterium that is difficult to treat in hospitals worldwide, leading to high mortality. Published data describing the use of monotherapy or combination therapy and which one is better is still unclear. We aimed to investigate the efficacy of monotherapy and combination therapy in the treatment of S. maltophilia infections. We performed a systematic review of combination therapy and additionally a systematic review and meta-analysis to determine the effects of monotherapy versus combination therapy on mortality in S. maltophilia infections. Electronic databases: Cochrane Library, PubMed, Embase, ClinicalTrials.gov, Scopus, and OpenGrey were accessed. Of the 5030 articles identified, 17 studies were included for a systematic review of combination therapy, of which 4 cohort studies were finally included for meta-analysis. We found there is a trend of favorable outcomes with respect to mortality in the use of combination therapy to treat complex or severe S. maltopholia infections. A meta-analysis of monotherapy showed a statistical significance in the decreasing rate of mortality in hospital-acquired pneumonia (hazard ratio 1.42; 95% confidence interval, 1.04-1.94) compared to combination therapy, but not significant in bacteremia (hazard ratio 0.76; 95% confidence interval, 0.18-3.18). Further studies should continue to explore this association.

Plazomicin against Multidrug-Resistant Bacteria: A Scoping Review

Plazomicin is a next-generation semisynthetic aminoglycoside antibiotic that can be used to treat infections by multi-resistant bacteria. It is effective against many bacteria-producing carbapenemases or other specific hydrolases. This scoping review aims to define the role acquired by plazomicin from its approval by the FDA (US Food and Drug Administration) in 2018 to the present day. Furthermore, we aim to provide a base for a future meta-analysis. This project was conducted following the recommendations presented in the PRISMA extension for scoping reviews and the JBI Manual for Evidence Synthesis. Among 901 potentially engaging citations, 345 duplicates were removed, and only 81 articles were selected for the analysis. According to the data analysis, plazomicin has been used to treat urinary tract infections, bloodstream infections, and ventilation-associated pneumonia. The pathogens killed included multi-resistant E. coli, K. pneumoniae, A. baumannii, P. aeruginosa, and S. aureus. Plazomicin can be a manageable, valid non-beta-lactam alternative for treating multi-resistant bacteria infections.