Real-world experience with meropenem/vaborbactam for the treatment of infections caused by ESBL-producing Enterobacterales and carbapenem-resistant Klebsiella pneumoniae.

PURPOSE: Real-world experience with meropenem/vaborbactam (M/V) is limited. Our aim is to report a clinical experience of M/V in the treatment of resistant Gram-negative bacilli. METHODS: This is a prospective observational study including patients hospitalized in the University Hospital of Pisa (March 2021-Jan 2023) with infections by both extended-spectrum ß-lactamases (ESBL)-producing Enterobacterales and carbapenem-resistant Klebsiella pneumoniae (Kp) treated with M/V. The primary outcome measure was clinical success, defined as a composite of survival, resolution of signs and symptoms and absence of microbiological failure at day 30 from infection onset. A multivariable regression analysis was performed to identify factors associated with clinical failure. Odds ratio (OR) with 95% confidence intervals (CI) was calculated. RESULTS: A total of 104 patients who received M/V were included: 24/104 (23.1%) infections were caused by ESBL non-hypervirulent Enterobacterales, 17/104 (16.3%) by ESBL-producing hypervirulent Klebsiella pneumoniae (hvKp) and 63/104 (60.6%) by CRE. The most common infections were bloodstream infections, followed by urinary tract infections, hospital-acquired pneumonia, intra-abdominal infections and others. Septic shock occurred in 16/104 (15.4%) patients. Clinical success was achieved in 77% of patients, and 30-day mortality rate was 15.4%. In patients with KPC-producing Kp infections, clinical success and 30-day mortality rates were 82% and 11.5%, respectively. On multivariable analysis, SOFA score (OR 1.32, 95% CI 1.02-1.7, p=0.032) was independently associated with clinical failure, while source control (OR 0.16, 95% CI 0.03-0.89, p=0.036) was protective. CONCLUSIONS: M/V is a promising therapeutic option against infections caused by difficult-to-treat ESBL-producing Enterobacterales and CR-Kp.

Clinical features and outcomes of infections caused by metallo-ß-lactamases producing Enterobacterales: a 3-year prospective study from an endemic area.

BACKGROUND: Metallo-ß-lactamases (MBL)-producing Enterobacterales are increasing worldwide. Our aim was to describe clinical features, treatments and outcomes of infections by MBL-Enterobacterales. METHODS: Prospective observational study conducted in the Pisa University Hospital (Jan 2019-Oct 2022) including patients with MBL-producing Enterobacterales infections. The primary outcome measure was 30-day mortality. A multivariable Cox regression analysis was performed to identify factors associated with 30-day mortality. Adjusted hazard ratio (aHR) (95% confidence intervals, CI) were calculated. RESULTS: 343 patients were included: 15 VIM- and 328 NDM-producing Enterobacterales infections. Overall, 199 (58%) were bloodstream infections, 60 (17.5%) hospital-acquired/ventilator-associated pneumonias, 60 (17.5%) complicated urinary tract infections, 13 (3.8%) intra-abdominal infections, 11 (3.2%) skin and soft tissue infections. Thirty-day mortality was 29.7%. Thirty-two patients did not receive in vitro active antibiotic therapy, 215/343 (62.7%) received ceftazidime-avibactam (CZA) plus aztreonam (ATM), 33/343 (9.6%) cefiderocol-containing regimens, 26/343 (7.6%) colistin-containing regimens and 37 (10.8%) other active antibiotics. On multivariable analysis, septic shock (aHR 3.57, 95% CI 2.05-6.23, p<0.001) and age (aHR 1.05, 95% CI 1.03-1.08, p<0.001) were independently associated with 30-day mortality, while in vitro active antibiotic therapy within 48 hours from infection (aHR 0.48, 95% CI 0.26-0.8, p=0.007) and source control (aHR 0.43, 95% CI 0.26-0.72, p=0.001) were protective factors. Sensitivity analysis showed that CZA plus ATM compared to colistin was independently associated with reduced 30-day mortality (aHR 0.39, 95% CI 0.18-0.86, p=0.019). Propensity score analyses confirmed these findings. CONCLUSIONS: MBL-CRE infections are associated with high 30-day mortality rates. Patients with MBL-producing Enterobacterales infections should received early active antibiotic therapy.

Investigating Resistance to Carbapenems in Enterobacterales: A Descriptive Epidemiological Study of 2021 Screening in an Italian Teaching Hospital.

Antimicrobial resistance (AMR) presents a growing threat to global healthcare. This descriptive epidemiological study investigates the prevalence and characteristics of Enterobacterales with AMR factors in a tertiary teaching hospital in Italy over the course of the year 2021. In 2021, the prevalence of colonisation by Enterobacterales with AMR factors in patients was 1.08%. During the observation period, a total of 8834 rectal swabs were performed, with 1453 testing positive. A total of 5639 rectal swabs were performed according to a hospital procedure for the active screening of MDRO colonisation at the time of admission. Of these, 679 were positive for microorganisms under surveillance, and 74 patients were colonised with Enterobacterales, predominantly Klebsiella pneumoniae and Escherichia coli. Antibiotic resistance factors were observed in 61 of these 74 patients (82.43%) of these patients, with NDM and KPC being the most frequent resistance factors. A statistically significant trend in positive swabs was observed across different ward categories (surgery, ICUs, and medical wards). Regarding specific trends, the rate of positive admission screening in medical and surgical wards was higher than in ICU wards. The results highlight the ease with which Enterobacterales develops resistance across different ward categories. The findings underscore the need for adjusted screening protocols and tailored infection prevention strategies in various care settings.

Salvage therapy with sulbactam/durlobactam against cefiderocol-resistant Acinetobacter baumannii in a critically ill burn patient: clinical challenges and molecular characterization.

Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) infections are associated with high mortality rates. The optimal treatment regimen for CRAB has not been defined. Cefiderocol has been recently introduced in the armamentarium against CRAB but there is concern about treatment-emergent resistance. Since mortality rates in CRAB infections remain high, further antibiotic options are needed. Methods: We report a case of severe infection by CRAB resistant to both colistin and cefiderocol treated with sulbactam/durlobactam and describe the molecular features of the strain. Susceptibility to cefiderocol was detected by disc diffusion according to EUCAST breakpoints. Susceptibility to sulbactam/durlobactam was determined by Etest according to preliminary breakpoints provided by Entasis Therapeutics. Whole Genome Sequencing (WGS) of the CRAB isolate was performed. Results: A burn patient with ventilator-associated pneumonia by CRAB resistant to colistin and cefiderocol received sulbactam/durlobactam as compassionate use. She was alive after 30 days from the end of therapy. Complete microbiological eradication of CRAB was achieved. The isolate harboured blaADC-30, blaOXA-23 and blaOXA-66. A missense mutation in PBP3 was detected. The isolate harboured a mutation in the TonB-dependent siderophore receptor gene piuA that showed a frameshift mutation causing a premature stop codon (K384fs). Moreover, the fepA gene, which is orthologous to pirA, was interrupted by a transposon insertion P635-ISAba125 (IS30 family). Conclusions: Further treatment options for severe infections by CRAB resistant to all available antibiotics are urgently needed. Sulbactam/durlobactam may be a future option against MDR A. baumannii.

Adoption of Improved Reprocessing Decreased Microbiological Non-Compliance for Bronchoscopes.

BACKGROUND: In the past few decades, the inadequate reprocessing of bronchoscopes has been associated with several serious outbreaks caused by multidrug-resistant microorganisms. In this study we evaluated the improvement in the quality of reprocessing in a Bronchoscopy Unit (BU), after the introduction of a new procedure. METHODS: In 2019, observational and clinical audits were conducted in the BU. After the introduction of an improved procedure in 2020, a microbiological surveillance plan was implemented in 2021. RESULTS: In 2019, 13 of 22 bronchoscopes (59%) resulted as non-compliant, 18% as high concern organisms (HCO) and 36.4% as high microbial count (≥100 CFU/all channels) and HCO. The most frequent microorganisms were Staphylococcus aureus (38.5%) and NDM-producing Klebsiella pneumoniae (15.4%). The bronchoscopes were stored inside their transport cases, which in some cases were found to be contaminated by the same strains isolated on the bronchoscopes (Enterobacter gergoviae and Vibrio alginolyticus). In 2021, all 31 bronchoscopes were sampled at least three times and 13/99 (13.1%) resulted as non-compliant, mostly K. pneumoniae (4.04%). Contamination level increases weakly in bronchoscopes in use for more than 14 years (R = 0.32). CONCLUSIONS: The adoption of an improved reprocessing procedure decreased the non-compliance of bronchoscopes, increasing the quality of the process and patient safety.

Resistome and virulome accretion in an NDM-1-producing ST147 sublineage of Klebsiella pneumoniae associated with an outbreak in Tuscany, Italy: a genotypic and phenotypic characterisation.

BACKGROUND: Carbapenemase-producing Enterobacterales (CPE), particularly those producing metallo-ß-lactamases, are among the most challenging antibiotic-resistant pathogens, causing outbreaks of difficult-to-treat nosocomial infections worldwide. Since November 2018, an outbreak of New Delhi metallo-ß-lactamases-positive CPE (NDM-CPE) has emerged in Tuscany, Italy. In this study, we aimed to investigate the NDM-CPE associated with the outbreak and characterise the responsible Klebsiella pneumoniae clone. METHODS: We used whole-genome sequencing and bioinformatic analysis to characterise NDM-CPE isolates that caused bloodstream infections in 53 patients at 11 hospitals in Tuscany and that were collected between Jan 1, 2018, and July 5, 2019 (ie, the early phase of the outbreak and preceding months). The CPE isolates characterised in this study were isolated and identified at the species level and as NDM producers by six diagnostic microbiology laboratories that serve the 11 hospitals. We used comparative genomic analysis, antimicrobial susceptibility testing, plasmid conjugal transfer assays, evaluation of virulence potential in the Galleria mellonella infection model, and serum bactericidal assays to further characterise the clone causing the outbreak. FINDINGS: The outbreak was sustained by an ST147 K pneumoniae producing NDM-1, which had a complex resistome that mediated resistance to most antimicrobials (except cefiderocol, the aztreonam-avibactam combination, colistin, and fosfomycin). The clone belonged to a sublineage of probably recent evolution, occurred by the sequential acquisition of an integrative and conjugative element encoding the yersiniabactin siderophore, an FIB(pQil)-type multiresistance plasmid carrying blaNDM-1, and a transferable chimeric plasmid, derived from virulence elements of hypervirulent K pneumoniae, carrying several resistance and virulence determinants. Infection of G mellonella larvae revealed a variable virulence potential. The behaviour in serum bactericidal assays was different from typical hypervirulent K pneumoniae strains, with variable grades of serum resistance apparently associated with mutations in specific chromosomal loci (csrD, pal, and ramR). INTERPRETATION: This description of a sublineage of ST147 K pneumoniae with a complex resistome and virulome that is capable of sustaining a large regional outbreak adds to existing research on the evolutionary trajectories within high-risk clones of K pneumoniae. Global surveillance programmes are warranted to track the dissemination of these lineages, and to prevent and control their spread. FUNDING: Italian Ministry of Health and Department of Experimental and Clinical Medicine, University of Florence.

Orthopaedic Implant-Associated Staphylococcal Infections: A Critical Reappraisal of Unmet Clinical Needs Associated with the Implementation of the Best Antibiotic Choice.

Infections associated with orthopaedic implants represent a major health concern characterized by a remarkable incidence of morbidity and mortality. The wide variety of clinical scenarios encountered in the heterogeneous world of infections associated with orthopaedic implants makes the implementation of an optimal and standardized antimicrobial treatment challenging. Antibiotic bone penetration, anti-biofilm activity, long-term safety, and drug choice/dosage regimens favouring outpatient management (i.e., long-acting or oral agents) play a major role in regards to the chronic evolution of these infections. The aim of this multidisciplinary opinion article is to summarize evidence supporting the use of the different anti-staphylococcal agents in terms of microbiological and pharmacological optimization according to bone penetration, anti-biofilm activity, long-term safety, and feasibility for outpatient regimens, and to provide a useful guide for clinicians in the management of patients affected by staphylococcal infections associated with orthopaedic implants Novel long-acting lipoglycopeptides, and particularly dalbavancin, alone or in combination with rifampicin, could represent the best antibiotic choice according to real-world evidence and pharmacokinetic/pharmacodynamic properties. The implementation of a multidisciplinary taskforce and close cooperation between microbiologists and clinicians is crucial for providing the best care in this scenario.

Cefiderocol- Compared to Colistin-Based Regimens for the Treatment of Severe Infections Caused by Carbapenem-Resistant Acinetobacter baumannii.

Cefiderocol may represent a therapeutic option for carbapenem-resistant Acinetobacter baumannii (CRAB) infections, but clinical data are limited. This is an observational retrospective study conducted in the University Hospital of Pisa including consecutive patients with CRAB infections (January 2020 to August 2021). Patients were divided in two study groups according to the antibiotic treatment received: cefiderocol- and colistin-containing regimens. The primary outcome was the 30-day mortality. A Cox regression analysis was performed to identify factors independently associated with 30-day mortality. A propensity score analysis using inverse probability of treatment weighting (IPTW) was also performed. A total of 124 patients were included: 47 (37.9%) received cefiderocol, while 77 (62.1%) colistin-containing regimens. Overall, 79 (63.7%) patients had a bloodstream infection (BSI), 35 (28.5%) a ventilator-associated pneumonia (VAP) and 10 (8.1%) other infections. Thirty-day mortality was higher in patients receiving colistin- compared to those who received cefiderocol-containing regimens (55.8% versus 34%, P = 0.018). This difference was confirmed in patients with BSI, but not in those with VAP. On multivariable analysis, septic shock, SOFA score, and age were independently associated with 30-day mortality, while cefiderocol therapy was protective in an IPTW analysis (Hazard ratio 0.44, 95% confidence interval 0.22-0.66, P < 0.001). Nephrotoxicity was more common in the colistin group. Microbiological failure occurred in 17.4% of patients receiving cefiderocol versus 6.8% of those receiving colistin (P = 0.079). Among 8 cases in the cefiderocol group who experienced microbiological failure, 4 (50%) developed resistance to cefiderocol. Cefiderocol represents a promising therapeutic option in patients with severe CRAB infections. Randomized clinical trial in this specific patient population should confirm our findings.

Spread of hypervirulent multidrug-resistant ST147 Klebsiella pneumoniae in patients with severe COVID-19: an observational study from Italy, 2020-21.

OBJECTIVES: To report an outbreak of hypervirulent Klebsiella pneumoniae (hvKp) in COVID-19 patients. METHODS: Prospective, observational study including consecutive COVID-19 patients with hvKp infections admitted to the University Hospital of Pisa (Italy). Clinical data and outcome of patients were collected. All patients were followed-up to 30 days from the diagnosis of infection. Mortality within 30 days of the diagnosis of hvKp infection was reported. The hypermucoviscous phenotype was determined by the 'string test'. Molecular typing was performed on three strains collected during different periods of the outbreak. The strains underwent whole genome sequencing using the Illumina MiSeq instrument. The complete circular assemblies were also obtained for the chromosome and a large plasmid using the Unicycler tool. RESULTS: From November 2020 to March 2021, hvKp has been isolated from 36 COVID-19 patients: 29/36 (80.6%) had infections (15 bloodstream infections, 8 ventilator-associated pneumonias and 6 complicated urinary tract infections), while 7/36 (19.4%) had colonization (3 urine, 2 rectal and 2 skin). The isolates belonged to ST147 and their plasmid carried three replicons of the IncFIB (Mar), IncR and IncHI1B types and several resistance genes, including the rmpADC genes encoding enhancers of capsular synthesis. The hvKp isolates displayed an ESBL phenotype, with resistance to piperacillin/tazobactam and ceftolozane/tazobactam and susceptibility only to meropenem and ceftazidime/avibactam. The majority of patients were treated with meropenem alone or in combination with fosfomycin. Thirty-day mortality was 48.3% (14/29). CONCLUSIONS: ST147 ESBL-producing hvKp is associated with high mortality in COVID-19 patients. Strict microbiological surveillance and infection control measures are needed in this population.

Bloodstream infections in patients with rectal colonization by Klebsiella pneumoniae producing different type of carbapenemases: a prospective, cohort study (CHIMERA study).

OBJECTIVE: To investigate the hypothesis that intestinal colonization by different types of carbapenemase-resistant Klebsiella pneumoniae (CR-Kp) leads to different risks for bloodstream infections (BSI) caused by the same colonizing organism. METHODS: Prospective observational study including consecutive CR-Kp rectal carriers admitted to the Pisa University Hospital (December 2018 to December 2019). Patients underwent rectal swabbing with molecular testing for the different carbapenemases at hospital admission and during hospitalization. Rectal carriers were classified as: NDM, KPC, VIM and OXA-48. The primary end point was the rate of BSI by the same colonizing organism in each study group. A multivariate logistic regression analysis was performed to identify factors independently associated with the risk for BSI by the colonizing organism. RESULTS: Of 677 rectal carriers, 382/677 (56.4%) were colonized by NDM, 247/677 (36.5%) by KPC, 39/677 (5.8%) by VIM and 9/677 (1.3%) by OXA-48. Dissemination of NDM-Kp was mostly sustained by ST147, while KPC-Kp belonged to ST512. A higher rate of BSI was documented in NDM rectal carriers compared with KPC rectal carriers (59/382, 15.4% versus 20/247, 8.1%, p 0.004). Incidence rates of BSI per 100 patients/month were significantly higher in the NDM group (22.33, 95% CI 17.26-28.88) than in the KPC group (9.56, 95% CI 6.17-14.82). On multivariate analysis, multi-site extraintestinal colonization, solid organ transplantation, invasive procedures, intravascular device, admission to intensive care unit, cephalosporin, fluoroquinolones and NDM rectal colonization (OR 3.27, 95% CI 1.73-6.18, p < 0.001) were independently associated with BSI. CONCLUSIONS: NDM-Kp was associated with increased risk of BSI compared with KPC-Kp. This finding seems to be strongly related to the high-risk clone ST147.

Colistin Resistance Onset Strategies and Genomic Mosaicism in Clinical Acinetobacter baumannii Lineages.

The treatment of multidrug-resistant Gram-negative infections is based on colistin. As result, COL-resistance (COL-R) can develop and spread. In Acinetobacter baumannii, a crucial step is to understand COL-R onset and stability, still far to be elucidated. COL-R phenotypic stability, onset modalities, and phylogenomics were investigated in a clinical A. baumannii sample showing a COL resistant (COLR) phenotype at first isolation. COL-R was confirmed by Minimum-Inhibitory-Concentrations as well as investigated by Resistance-Induction assays and Population-Analysis-Profiles (PAPs) to determine: (i) stability; (ii) inducibility; (iii) heteroresistance. Genomics was performed by Mi-Seq Whole-Genome-Sequencing, Phylogenesis, and Genomic Epidemiology by bioinformatics. COLRA. baumannii were subdivided as follows: (i) 3 A. baumannii with stable and high COL MICs defining the "homogeneous-resistant" onset phenotype; (ii) 6 A. baumannii with variable and lower COL MICs displaying a "COL-inducible" onset phenotype responsible for adaptive-resistance or a "subpopulation" onset phenotype responsible for COL-heteroresistance. COL-R stability and onset strategies were not uniquely linked to the amount of LPS and cell envelope charge. Phylogenomics categorized 3 lineages clustering stable and/or unstable COL-R phenotypes with increasing genomic complexity. Likewise, different nsSNP profiling in genes already associated with COL-R marked the stable and/or unstable COL-R phenotypes. Our investigation finds out that A. baumannii can range through unstable or stable COLR phenotypes emerging via different "onset strategies" within phylogenetic lineages displaying increasing genomic mosaicism.

Meropenem-Vaborbactam as Salvage Therapy for Ceftazidime-Avibactam-, Cefiderocol-Resistant ST-512 Klebsiella pneumoniae-Producing KPC-31, a D179Y Variant of KPC-3.

A 68-year-old man had recurrent bacteremia by Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae resistant to ceftazidime-avibactam and cefiderocol. The sequencing of a target region showed that it harbored a KPC-3 variant enzyme (D179Y; KPC-31), which confers resistance to ceftazidime-avibactam and restores meropenem susceptibility. The patient was successfully treated with meropenem-vaborbactam.

Cefiderocol as Rescue Therapy for Acinetobacter baumannii and Other Carbapenem-resistant Gram-negative Infections in Intensive Care Unit Patients.

Ten critically ill patients with either bacteremia or ventilator-associated pneumonia caused by carbapenem-resistant Acinetobacter baumannii, Stenotrophomonas maltophilia, or New Delhi metallo-ß-lactamase-producing Klebsiella pneumoniae received cefiderocol. All strains had minimum inhibitory concentration ≤2 µg/mL. Thirty-day clinical success and survival rates were 70% and 90%, respectively. Two patients had a microbiological failure. Future prospective studies are warranted.

Efficacy of Ceftazidime-avibactam Plus Aztreonam in Patients With Bloodstream Infections Caused by Metallo-ß-lactamase-Producing Enterobacterales.

BACKGROUND: In vitro data support the use of combination of aztreonam (ATM) with ceftazidime-avibactam (CAZ-AVI), but clinical studies are lacking. The aim of our study was to compare the outcome of patients with bloodstream infections (BSIs) due to metallo-ß-lactamase (MBL)-producing Enterobacterales treated either with CAZ-AVI plus ATM or other active antibiotics (OAAs). METHODS: This was a prospective observational study including patients admitted to 3 hospitals in Italy and Greece. The primary outcome measure was 30-day all-cause mortality. Secondary outcomes were clinical failure at day 14 and length of stay after BSI diagnosis. Cox regression analysis including a propensity score (PS) for receiving CAZ-AVI + ATM was performed to evaluate primary and secondary outcomes. A PS-based matched analysis was also performed. RESULTS: We enrolled 102 patients with BSI; 82 had infections caused by NDM-producing (79 Klebsiella pneumoniae and 3 Escherichia coli) and 20 by VIM-producing (14 K. pneumoniae, 5 Enterobacter species, 1 Morganella morganii) strains. The 30-day mortality rate was 19.2% in the CAZ-AVI + ATM group vs 44% in the OAA group (P = .007). The PS-adjusted analysis showed that the use of CAZ-AVI + ATM was associated with lower 30-day mortality (hazard ratio [HR], 0.37 [95% confidence interval {CI}, .13-.74]; P = .01), lower clinical failure at day 14 (HR, 0.30 [95% CI, .14-.65]; P = .002), and shorter length of stay (subdistributional HR, 0.49 [95% CI, .30-.82]; P = .007). The PS-matched analysis confirmed these findings. CONCLUSIONS: The CAZ-AVI + ATM combination offers a therapeutic advantage compared to OAAs for patients with BSI due to MBL-producing Enterobacterales. Further studies are warranted.

Predictors of hospital-acquired bacterial and fungal superinfections in COVID-19: a prospective observational study.

BACKGROUND: Bacterial and fungal superinfections may complicate the course of hospitalized patients with COVID-19. OBJECTIVES: To identify predictors of superinfections in COVID-19. METHODS: Prospective, observational study including patients with COVID-19 consecutively admitted to the University Hospital of Pisa, Italy, between 4 March and 30 April 2020. Clinical data and outcomes were registered. Superinfection was defined as a bacterial or fungal infection that occurred ≥48 h after hospital admission. A multivariate analysis was performed to identify factors independently associated with superinfections. RESULTS: Overall, 315 patients with COVID-19 were hospitalized and 109 episodes of superinfections were documented in 69 (21.9%) patients. The median time from admission to superinfection was 19 days (range 11-29.75). Superinfections were caused by Enterobacterales (44.9%), non-fermenting Gram-negative bacilli (15.6%), Gram-positive bacteria (15.6%) and fungi (5.5%). Polymicrobial infections accounted for 18.3%. Predictors of superinfections were: intestinal colonization by carbapenem-resistant Enterobacterales (OR 16.03, 95% CI 6.5-39.5, P < 0.001); invasive mechanical ventilation (OR 5.6, 95% CI 2.4-13.1, P < 0.001); immunomodulatory agents (tocilizumab/baricitinib) (OR 5.09, 95% CI 2.2-11.8, P < 0.001); C-reactive protein on admission >7 mg/dl (OR 3.59, 95% CI 1.7-7.7, P = 0.001); and previous treatment with piperacillin/tazobactam (OR 2.85, 95% CI 1.1-7.2, P = 0.028). Length of hospital stay was longer in patients who developed superinfections ompared with those who did not (30 versus 11 days, P < 0.001), while mortality rates were similar (18.8% versus 23.2%, P = 0.445). CONCLUSIONS: The risk of bacterial and fungal superinfections in COVID-19 is consistent. Patients who need empiric broad-spectrum antibiotics and immunomodulant drugs should be carefully selected. Infection control rules must be reinforced.

Extremely drug-resistant NDM-9-producing ST147 Klebsiella pneumoniae causing infections in Italy, May 2020.

A large outbreak of New Delhi metallo-beta-lactamase (NDM)-1-producing Klebsiella pneumoniae sequence type (ST) 147 occurred in Tuscany, Italy in 2018-2019. In 2020, ST147 NDM-9-producing K. pneumoniae were detected at the University Hospital of Pisa, Tuscany, in two critically ill patients; one developed bacteraemia. Genomic and phylogenetic analyses suggest relatedness of 2018-2019 and 2020 strains, with a change from NDM-1 to NDM-9 in the latter and evolution by colistin, tigecycline and fosfomycin resistance acquisition.

Comparison of methods for the microbiological diagnosis of totally implantable venous access port-related infections.

Introduction. Totally implanted venous access ports (TIVAPs) are widely used in patients receiving long-term chemotherapy but may lead to serious complications such as catheter-related bloodstream infections (CRBSIs). Diagnosis of CRBSI requires catheter culture, but there is no consensus on microbiological culture methods to be adopted.Aim. To compare three different procedures to recover bacterial cells from colonized catheters and to determine which section of the TIVAP (i.e. tip, septum, reservoir) is the probable source of infection. To investigate the correlation between blood culture results and TIVAP culture in order to get further evidence about the utility of differential time to positivity (DTP) as a diagnostic tool before TIVAP removal.Hypothesis/Gap statement. Comparisons of different diagnostic procedures for catheter culture have been rarely reported for TIVAPs. We hypothesized that the optimization of methods to recover micro-organisms from different parts of TIVAPs may help to decrease the number of false-negative results in the diagnosis of TIVAP-related bloodstream infections.Methodology. A total of 53 TIVAPs removed because of suspected infection (n=36) or end of use (n=17) were evaluated. The reservoir, the septum and the catheter tip were separated and subjected to different treatments for the recovery of adherent micro-organisms: (a) flushing of the catheter lumen, (b) sonication and flushing, (c) treatment with dithiothreitol and flushing. The three methods were also evaluated in an in vitro catheter infection model with Staphylococcus epidermidis. Culture results were compared to those obtained from paired blood cultures drawn from TIVAP and peripheral vein and to the relative DTP.Results. The results obtained demonstrated that vigorous flushing/vortexing of the catheter lumen/septum, allows the recovery of a number of micro-organisms comparable to that of more complex procedures such as sonication or chemical treatment. Among 24 positive TIVAP-cultures, nine were tip-culture negative, whereas the corresponding reservoirs and septa were culture positive. A good correlation was observed between DTP and TIVAP cultures (P<0.001).Conclusions. The results support the evidence that sending the port reservoir in addition to the catheter tip to the microbiology laboratory may increase the sensitivity and the accuracy of CRBSI diagnosis. Moreover, when a TIVAP-related infection is suspected, DTP is a useful diagnostic tool to decide between device removal or a more conservative approach.

Increased Risk of Acquisition of New Delhi Metallo-Beta-Lactamase-Producing Carbapenem-Resistant Enterobacterales (NDM-CRE) among a Cohort of COVID-19 Patients in a Teaching Hospital in Tuscany, Italy.

We describe the epidemiology of New Delhi Metallo-Beta-Lactamase-Producing Carbapenem-Resistant Enterobacterales (NDM-CRE) colonization/infection in a cohort of COVID-19 patients in an Italian teaching hospital. These patients had an increased risk of NDM-CRE acquisition versus the usual patients (75.9 vs. 25.3 cases/10,000 patient days). The co-infection significantly increased the duration of hospital stay (32.9 vs. 15.8 days).