Carbapenemase-producing Bacteria Research Articles

Epidemiology and clinical significance of carbapenemases in Australia: a narrative review.

Carbapenemase-producing gram-negative bacteria (CP-GNB) infections threaten public health with high mortality, morbidity and treatment costs. Although frequencies remain low in Australia (total number of CP-GNB infections reported was 907 in 2022), blaIMP-4 has established low levels of endemicity in many states. Imipenemase metallo-β-lactamase types alone accounted for more than half of all carbapenemases in carbapenemase-producing Enterobacterales isolates in Australia, particularly in Enterobacter cloacae complex. New Delhi metallo-β-lactamase constitutes almost 25% of all carbapenemases in Australia and was identified predominantly in Escherichia coli. The OXA-48-like carbapenemases include almost 10% of all carbapenemases and are mainly seen in Klebsiella pneumoniae and E. coli. Although K. pneumoniae carbapenemase-type carbapenemases are rare in Australia, some local outbreaks have occurred. Most carbapenem-resistant (CR) Pseudomonas aeruginosa strains in Australia do not produce carbapenemases. Finally, OXA-23-like carbapenemases are overwhelmingly positive in CR-Acinetobacter baumannii strains in Australia. Treatment of CR-GNB infections challenges physicians. Of 10 new antibiotics active against at least some CR-GNB infections that are approved by the USFood and Drug Administration, just three are approved for use in Australia. In this context, there is still an unmet need for novel antibacterials that can be used for the treatmentof CR-GNB infections in Australia, as well as a pressing requirement for new mechanisms to 'de-link' antibiotic sales from their availability. In this narrative review, we aim to overview the epidemiology and clinical significance of carbapenem resistance in Australia as it pertains to Enterobacterales, P. aeruginosa and A. baumannii.

Rapid detection of carbapenemase-producing gram-negative bacteria directly from blood culture bottles for a reliable guided empiric therapy.

Bloodstream infections (BSIs) caused by multidrug-resistant bacteria are a critical life-threatening challenge which necessitates the urgency to trigger life-saving treatment in a timely manner. This study aimed to evaluate the time required for rapid detection of carbapenemase-producing Enterobacterales (CPE) directly from blood culture bottles to optimize empirical treatment of BSI, especially in pediatric and infant patients, using a cost-effective method. This study included 419 Gram-negative bacteria, of which Klebsiella pneumoniae and Escherichia coli were the most common CPE causing BSI in pediatric and neonatal patients. Phenotypic and genotypic resistance of the selected isolates (45 K. pneumoniae and 9 E. coli) were determined by VITEK-2 Compact system and PCR, respectively. BACT/ALERT bottles were spiked with isolates. Finally, colorimetric RESIST-BC assay and Vitek-2 compact system were evaluated for the rapid detection of carbapenem-resistant bacteria directly from positive blood culture bottles. All selected isolates were phenotypically resistant to carbapenems. PCR showed that blaNDM and blaOXA-48 were present in all isolates, blaVIM was present in 44.4%, while blaKPC and blaIMP were entirely absent. The RESIST-BC kit showed good agreement with PCR for blaNDM and blaOXA-48, demonstrating high sensitivity and specificity, but not with blaVIM. These findings point out that RESIST-BC assay demonstrated an exceptionally short detection time for CPE, completing all cases within the first hour after the blood culture bottles flagged positive. It is also superior in providing a cluefor clinicians on antibiotic combinations that can be administered, depending on the type of β-lactamases detected, promptly and efficiently, with low expenses.

The Triple Combination of Meropenem, Avibactam, and a Metallo-β-Lactamase Inhibitor Optimizes Antibacterial Coverage Against Different β-Lactamase Producers

This work explores the potential of a triple combination of meropenem (MEM), a novel metallo-β-lactamase (MBL) inhibitor (indole-2-carboxylate 58 (InC58)), and a serine-β-lactamase (SBL) inhibitor (avibactam (AVI)) for broad-spectrum activity against carbapenemase-producing bacteria. A diverse panel comprising MBL- and SBL-producing strains was used for susceptibility testing of the triple combination using the agar dilution method. The frequency of resistance (FoR) to MEM combined with InC58 was investigated. Mutants were sequenced and tested for cross resistance, fitness, and the stability of the resistance phenotype. Compared with the double combinations of MEM plus an SBL or MBL inhibitor, the triple combination extended the spectrum of activity to most of the isolates bearing SBLs (oxacillinase-48 (OXA-48) and Klebsiella pneumoniae carbapenemase-2 (KPC-2)) and MBLs (New Delhi metallo-β-lactamases (NDMs)), although it was not effective against Verona Integron-encoded metallo-β-lactamase (VIM)-carrying Pseudomonas aeruginosa (P. aeruginosa) and OXA-23-carrying Acinetobacter baumannii (A. baumannii). The FoR to MEM plus InC58 ranged from 1.13 × 10–6 to 2.22 × 10–7. The resistance correlated with mutations to ompC and comR, affecting porin C and copper permeability, respectively. The mutants manifested a fitness cost, a decreased level of resistance during passage without antibiotic pressure, and cross resistance to another carbapenem (imipenem) and a β-lactamase inhibitor (taniborbactam). In conclusion, compared with the dual combinations, the triple combination of MEM with InC58 and AVI showed a much wider spectrum of activity against different carbapenemase-producing bacteria, revealing a new strategy to combat β-lactamase-mediated antimicrobial resistance.

Colonisation of hospital surfaces from low- and middle-income countries by extended spectrum β-lactamase- and carbapenemase-producing bacteria

Hospital surfaces can harbour bacterial pathogens, which may disseminate and cause nosocomial infections, contributing towards mortality in low- and middle-income countries (LMICs). During the BARNARDS study, hospital surfaces from neonatal wards were sampled to assess the degree of environmental surface and patient care equipment colonisation by Gram-negative bacteria (GNB) carrying antibiotic resistance genes (ARGs). Here, we perform PCR screening for extended-spectrum β-lactamases (blaCTX-M-15) and carbapenemases (blaNDM, blaOXA-48-like and blaKPC), MALDI-TOF MS identification of GNB carrying ARGs, and further analysis by whole genome sequencing of bacterial isolates. We determine presence of consistently dominant clones and their relatedness to strains causing neonatal sepsis. Higher prevalence of carbapenemases is observed in Pakistan, Bangladesh, and Ethiopia, compared to other countries, and are mostly found in surfaces near the sink drain. Klebsiella pneumoniae, Enterobacter hormaechei, Acinetobacter baumannii, Serratia marcescens and Leclercia adecarboxylata are dominant; ST15 K. pneumoniae is identified from the same ward on multiple occasions suggesting clonal persistence within the same environment, and is found to be identical to isolates causing neonatal sepsis in Pakistan over similar time periods. Our data suggests persistence of dominant clones across multiple time points, highlighting the need for assessment of Infection Prevention and Control guidelines.

O03 Phenotypic antimicrobial resistance to last-resort antibiotics in carbapenemase-producing bacteria from Ukrainian patients

Abstract Background Since March 2022, there has been an emergence of MDR microorganisms (MDRO) in Europe because of an increasing number of Ukrainian patients with MDRO. The goal was to collect large-scale phenotypic susceptibility data to assess implications for clinical practice. Methods For 122 MDRO (carbapenemase-producing Enterobacterales (CPE, n=96), Pseudomonas aeruginosa CPPA (n=20), carbapenem-resistant Acinetobacter baumannii-calcoaceticus (CRAB, n=6), collected from March to December 2022, broth microdilution (BMD), fosfomycin agar dilution, gradient strip ampicillin/sulbactam, sulbactam/durlobactam, ceftazidime-avibactam-aztreonam and disc diffusion (DD) cefiderocol was performed. Epidemiological data was obtained as part of mandatory reporting by Municipal Health Services (CPE), and surveillance questionnaires (CPPA/CRAB). Results Admission at a Ukrainian hospital in the last year was a risk factor for acquiring MDRO. Of all isolates, 65% (79/122) were blaNDM-positive. For meropenem, aminoglycosides, ceftazidime-avibactam, ceftolozane-tazobactam and imipenem-relebactam susceptibility rates were low (0-30%). For cefiderocol, results depended on reading with or without microcolonies, applying EUCAST or CLSI breakpoints, and whether DD or BMD was used: e.g. for Klebsiella pneumoniae, 30%–97% were susceptible, depending on these variables. For colistin, 103/111 (93%) non-intrinsically resistant CPE/CPPA/CRAB isolates were susceptible. For the majority of CPE, a low MIC of <0.5 mg/L was measured for tigecycline and ceftazidime-avibactam-aztreonam. For CPPA, cefiderocol tested susceptible in 65%–100% of isolates. For CRAB, ampicillin/sulbactam MICs were ≥128 mg/L, for sulbactam/durlobactam 1–2 mg/L. Conclusions There is extensive phenotypic resistance to last-resort antibiotics in carbapenemase-producing bacteria from Ukrainian patients. For cefiderocol, interpretation of susceptibility results depends on a number of variables. In case of infection, treatment options are colistin, cefiderocol (CPE/CPPA/CRAB), tigecycline (CPE/CRAB), ceftazidime-avibactam-aztreonam (CPE), sulbactam/durlobactam (CRAB).

Carbapenemase Detection and Identification: Which method should be Chosen?

Carbapenemase production constitutes the key mechanism of resistance to carbapenems. Rapid detection or confirmation of the involvement of carbapenemase-producing bacteria (CPB) in infections is crucial for adequate antibiotic therapy and infection control, particularly during epidemics or for surveillance purposes. The Ambler classification proposes four classes of carbapenemases: classes A, B, C, and D. Carbapenemases A, C, and D are called serine carbapenemases because they use serine in their active site to catalyze the hydrolysis of carbapenems. Class B carbapenemases are metallo-beta-lactamases (MBLs) that use a cation (Zn2+) to hydrolyze the beta-lactam ring. Biochemical, chromogenic, immunochromatographic, mass spectrometric, and molecular methods have both advantages and limitations for carbapenemase detection. Although there is no single method that meets all specifications of an ideal test, it is important to explore methods to identify the most suitable ones. Thus, according to the research articles reported in this review and the criteria (cost, turnaround time, sensitivity, specificity, expertise needs, target carbapenemases), chromogenic tests such as ChromID CARBA SMART and CHROMagar™ mSuperCARBA™ would be the best candidates for the rapid and effective detection of carbapenemase-producing bacteria in developing countries. Moreover, Carba NP, SUPERCARBA and Carbapenem Inactivation Method (CIM) could also be considered good carbapenemase-detecting methods. WGS may be reserved for large-scale funded studies of carbapenemase-producing bacteria.

Description of a nationwide structure for monitoring nosocomial outbreaks of (highly resistant) microorganisms in the Netherlands: characteristics of outbreaks in 2012–2021

BackgroundBefore 2012, established national surveillance systems in the Netherlands were not able to provide a timely, comprehensive epidemiological view on nosocomial outbreaks. The Healthcare-associated Infections and AntiMicrobial Resistance Monitoring Group (SO-ZI/AMR) was initiated in 2012 for timely national nosocomial outbreak monitoring and risk assessment. This paper aims to describe the achievements of the SO-ZI/AMR by presenting characteristics of outbreaks reported in 2012–2021.MethodsHospitals and, since 2015, long-term care facilities (LTCF) were requested to report outbreaks when (1) continuity of care was threatened, or (2) transmission continued despite control measures. A multi-disciplinary expert panel (re-)assessed the public health risk of outbreaks during monthly meetings, using 5 severity phases and based on data collected via standardised questionnaires. We descriptively studied the panel’s consensus-based severity classification, distribution of (highly resistant) microorganisms, and duration and size of outbreaks between April 2012 and December 2021.ResultsIn total, 353 hospital outbreaks and 110 LTCF outbreaks were reported. Most outbreaks (hospitals: n = 309 (88%), LTCF: n = 103 (94%)) did not progress beyond phase 1 (no public health implications, outbreak expected to be controlled within two months), one hospital outbreak reached phase 4 (insufficient/ineffective response: possible public health threat, support offered). Highly resistant microorganisms (HRMO) were involved in 269 (76%) hospital and 103 (94%) LTCF outbreaks. Most outbreaks were caused by methicillin-resistant Staphylococcus aureus (MRSA; n = 93 (26%) in hospitals, n = 80 (72%) in LTCF), vancomycin-resistant Enterococcus faecium (VRE; n = 116 (33%) in hospitals, n = 2 (2%) in LTCF) and highly resistant Enterobacterales (n = 41 (12%) in hospitals, n = 20 (18%) in LTCF). Carbapenemase-producing gram-negative bacteria were involved in 32 (9.1%) hospital and five (4.5%) LTCF outbreaks. In hospitals, VRE outbreaks had the longest duration (median 2.3; range 0.0-22.8 months) and widest range of affected patients (median 9; range 2-483).ConclusionsThe SO-ZI/AMR provided national insight into the characteristics of nosocomial outbreaks over the past decade. HRMO outbreaks – mostly caused by MRSA, VRE (in hospitals) and highly resistant Enterobacterales – occurred regularly, but most of them were controlled quickly and did not develop into a public health threat. The SO-ZI/AMR has become a solid monitoring body, essential to assess risks and raise awareness of potential HRMO threats.

717. Antimicrobial Resistance of Gram-Negative Bacteria in Respiratory Isolates from an Intensive Care Unit in Guatemala

Abstract Background Antimicrobial resistance (AMR) among Gram-negative bacteria (GNB) is a growing concern in public health, particularly in ICU settings. Over the past few decades, there has been a significant increase in ESBL and carbapenem resistance in Latin America, which has resulted in higher mortality rates and increased healthcare costs. One way to understand local bacterial resistance profiles is to examine respiratory isolates, which can serve as a proxy for resistance observed in the clinical setting. It is critical for clinicians to be aware of these profiles in order to make informed decisions about treatment options. Methods A retrospective study was conducted on all respiratory isolates from the ICU of a third-level national hospital over a 6-month period. All respiratory isolates were analyzed for to identify microorganisms and their AMR to selected antibiotics, including Ceftriaxone (CRO), Ceftazidime (CAZ), Cefepime (CEF) and carbapenems. Results A total of 500 isolates were obtained during the study period, resulting in the isolation of 988 microorganisms. GNB represented 92.3% (n=912) of these isolates. Pseudomonas spp was the most common GNB identified (28.07%), followed by Acinetobacter (26.97%) and Klebsiella spp (20.94%). Stenotrophomona isolates were excluded from the analysis as resistance profiling for this organism is not routinely performed in the institution, leaving a total of 868 isolates for AMR analysis. A total of 527 GNB isolates (60.78%) were identified as resistant to both 3rd generation cephalosporines and CEF. Strains with this resistance pattern were considered highly suggestive of ESBL production. Moreover, 66.78% (n=579) of GNB’s analyzed evidenced resistance to carbapenems, with 13.61% (n=118) of strains having been identified as carbapenemase-producing bacteria. Some GNB exhibited alarming levels of resistance as evidenced in table 1.Table 1.Resistance of selected GNBPercentage of bacterial strains from respiratory isolates resistant to selected antibiotics. Conclusion The high level or resistance observed in GNB from respiratory isolates in this study is concordant with other data from Latin America. While the prevalence of GNB in respiratory isolates does not necessarily correlates with clinical infection rates, the high level of resistance found may be an indicator of the AMR epidemiology of infections in this ICU. Disclosures All Authors: No reported disclosures

Carriage of multidrug-resistant carbapenemase-producing gram-negative bacteria in patients admitted to NHS Greater Glasgow and Clyde hospitals: Implications for treatment.

Infections caused by gram-negative carbapenemase-producing organisms (CPO) have become a global phenomenon. Screening of patients for CPO that was carried out at 48-h intervals enables early detection of carriers for infection control purposes and planning therapy. We investigated the bacterial flora detected on screening, the enzymes that conferred resistance and the proportion of patients who developed bacteraemia with CPO and their therapy. In all, 27 patients had a positive screen for CPO. A small but significant (7.5%) proportion of patients were not detected on initial screening. Escherichia coli and Klebsiella were predominant. New-Delhi metallo β-lactamase and oxacillin carbapenemases were the main enzymatic mechanisms of resistance. Four (14.8%) patients developed bacteraemia with CPO (30- and 90-day survival 100% and 75%, respectively). A single negative screen does not rule out colonisation. A significant proportion of patients colonised with CPO develop bacteraemia. Vigilance is needed to prevent the nosocomial spread of CPO.

Carbapenemase-Producing Bacteria Isolated from ICU Patients of a Peruvian Government Hospital during the COVID-19 Pandemic: A Descriptive Analysis.

Background and Objectives: In Peru, the presence of antimicrobial-resistant bacteria is a constant concern in hospitals and has likely increased in frequency during the pandemic. The objective of the study was to analyze the frequency of carbapenemase-producing bacteria resistant to two carbapenems (Imipenem and Meropenem), which were isolated from Peruvian patients in the intensive care unit of the Victor Lazarte Echegaray Hospital in Trujillo (Peru) during the COVID-19 pandemic. Materials and Methods: The biological samples of the patients hospitalized in the ICU were processed in the Microbiology Diagnostic Laboratory of the Víctor Lazarte Echegaray Hospital between May 2021 and March 2022. Antimicrobial sensitivity was determined with the automated system AutoScan-4, and for the identification of the type of carbapenemase, the RESISIT-3 O.K.N K-SET cassettes were used. Results: The results show that 76 cultures (76/129) had resistance to the two carbapenems (imipenem or meropenem), where the most frequent were Klebsiella pneuomoniae (31.6%), Pseudomonas aeruginosa (26.3%), and Acinetobacter baumannii (14.5%). Pseudomonas aeruginosa cultures showed at least three carbapenemase types (KPC, NDM, and OXA-48), while A. baumannii, Escherichia coli, and Burkholderia cepacia complex presented at least two carbapenemases (NDM and OXA-48). The carbapenemase NDM was detected in Enterobacter cloacae, Morganella morganii, and Proteus mirabilis, while KPC was present in all Klebsiella pneumoniae and Klebsiella oxytoca cultures. Conclusions: The samples from patients hospitalized in the Victor Lazarte Echegaray Hospital ICU showed a high prevalence of imipenem- and meropenem-resistant bacteria. These findings are relevant and concerning from the perspective of antibiotic-resistant bacteria monitoring, control, and disinfection. Thus, an appropriate antibiotic policy must be implemented.

Rapid and automated screening of carbapenemase- and ESBL-producing Gram-negative bacteria from rectal swabs using chromogenic agar media and the ScanStation device.

The ScanSation 100 device (Interscience, France) is an incubator allowing real-time detection of bacterial colony growth by frequently imaging agar plates over time, counting CFU, and detecting colony color. This study evaluated its performance for the early detection of carbapenemase-producing bacteria (CPB) and extended-spectrum β-Lactamase-producing bacteria (ESBL-PB) from rectal swabs inoculated on CHROMagar mSuperCARBA and ESBL media, respectively. Rectal screening ESwabs collected from patients admitted to Grenoble University Hospital between January and June 2021 were analyzed. After inoculation, chromogenic media were incubated for 24 h in the automaton, with image acquisition every 30 min. ScanStation results were compared to visual observations of the plates after 24 h of incubation. In total, 501 rectal swabs were tested. ScanStation showed 100% positive percent agreement (PPA) for the detection of CPB and ESBL-PB, whereas the PPA of color categorization ranged between 45% and 100%. Negative percent agreement (NPA) ranged between 70% and 98%. Negative predictive values (NPVs) were 100% for both bacterial groups, whereas positive predictive values (PPVs) were 70.3% for CPB and 81.0% for ESBL-PB. Importantly, real-time screening allowed detection of the first suspected colony within 10-14 h of growth, on average, whereas visual observation is usually only performed once a day after 18-24 h of incubation. Our study demonstrates the potential use of early images to accelerate the detection of CPB and ESBL-PB and implement effective and timely infection control measures. IMPORTANCE The ScanStation 100 device is an incubator able to follow the real-time growth of bacterial colonies on agar plates through digital imaging, allowing users to sort plates according to the presence or absence of colonies, and to distinguish their color using four numeric color filters. Real-time screening shows that first colony detection is possible much earlier (after 10-14 h of growth, on average), whereas visual observation is usually performed only once a day after 18-24 h of incubation. The ScanStation device, combined with chromogenic agar media, is an efficient automated screening method to accelerate the detection of Gram-negative multidrug-resistant bacteria in laboratories that do not have access to larger laboratory automation systems. Our study shows that setting the image acquisition to one or two early images may allow for the detection of positive samples that were inoculated in the morning, by the end of the working day.

B-066 Evaluation on Effectiveness of Colloidal Gold Immunochromatography Assay for Rapid Detection of Carbapenemase-producing Enterobacteriaceae

Abstract Background The identification, treatment, and control of carbapenem-resistant Enterobacteriaceae (CRE) infections are a major challenge for health care institutions and diagnostic laboratories worldwide. A novel Carbapenemase-producing Bacteria Test Kit (Lateral Flow Assay) from Dynamiker Biotechnology (Tianjin) Co., Ltd. is a qualitative test that was easy to operate and can be widely accepted by clinical and primary medical. Results can be read in just 15 minutes using colloidal gold immunochromatography, which can detect double and multiple carbapenemase types (Fig. 1). We analyzed the effectiveness of Dynamiker carbapenemase-producing bacteria test kit for rapid detection of CRE carbapenemase. Methods A total of 120 strains of Enterobacterales in blood culture were collected, including 80 strains of CRE and 40 strains of CSE (carbapenem-susceptibility Enterobacteriaceae). PCR was used to detect KPC, NDM, IMP, VIM and OXA-48 genes as gold standard. Dynamiker carbapenemase-producing bacteria test kit was used to detect the carbapenemase produced by CRE, which was conducted by the performance evaluation combined with PCR results. Results The 80 strains of CRE expressing carbapenemase genes were all positive for the detection of carbapenemasstre by Dynamiker carbapenemase-producing bacteria test kit, which includes 39 strains producing KPC, 26 strains producing NDM, 8 strains producing IMP, 5 strains producing VIM and 2 strains producing OXA-48 enzymes; the 40 strains of CSE were negative and no carbapenemase were detected. Compared with the PCR results, the sensitivity and specificity of the four enzymes by Dynamiker carbapenemase-producing bacteria test kit were both 100% (Fig. 2). Conclusion Dynamiker carbapenemase-producing bacteria test kit can be applied as a simple, rapid, sensitive and specific diagnostic method for the detection of different CRE carbapenemase types, which is of great value for the accurate use of clinical anti-infective therapy.Fig. 1.Operating procedures of colloidal gold immunochromatography.Fig. 2.Results of Dynamiker carbapenemase-producing bacteria test kit C: Control, K: KPC, N: NMD, I: IMP, V: VIM, O: OXA-48.

Genomic epidemiology of carbapenemase-producing Gram-negative bacteria at the human-animal-environment interface in Djibouti city, Djibouti

The emergence of carbapenem resistance is a major public health threat in sub-Saharan Africa but remains poorly understood, particularly at the human-animal-environment interface. This study provides the first One Health-based study on the epidemiology of Carbapenemase-Producing Gram-Negative Bacteria (CP-GNB) in Djibouti City, Djibouti, East Africa. In total, 800 community urine samples and 500 hospital specimens from humans, 270 livestock fecal samples, 60 fish samples, and 20 water samples were collected and tested for carbapenem resistance. The overall estimated CP-GNB prevalence was 1.9 % (32/1650 samples) and specifically concerned 0.3 % of community urine samples, 2.8 % of clinical specimens, 2.6 % of livestock fecal samples, 11.7 % of fish samples, and 10 % of water samples. The 32 CP-GNB included 19 Escherichia coli, seven Acinetobacter baumannii, five Klebsiella pneumoniae, and one Proteus mirabilis isolate. Short-read (Illumina) and long-read (Nanopore) genome sequencing revealed that carbapenem resistance was mainly associated with chromosomal carriage of blaNDM-1, blaOXA-23, blaOXA-48, blaOXA-66, and blaOXA-69 in A. baumannii, and with plasmid carriage in Enterobacterales (blaNDM-1 and blaOXA-181 in E. coli, blaNDM-1, blaNDM-5 and blaOXA-48 in K. pneumoniae, and blaNDM-1 in P. mirabilis). Moreover, 17/32 CP-GNB isolates belonged to three epidemic clones: (1) A. baumannii sequence type (ST) 1697,2535 that showed a distribution pattern consistent with intra- and inter-hospital dissemination; (2) E. coli ST10 that circulated at the human-animal-environment interface; and (3) K. pneumoniae ST147 that circulated at the human-environment interface. Horizontal exchanges probably contributed to carbapenem resistance dissemination in the city, especially the blaOXA-181-carrying ColKP3-IncX3 hybrid plasmid that was found in E. coli isolates belonging to different STs. Our study highlights that despite a relatively low CP-GNB prevalence in Djibouti City, plasmids harboring carbapenem resistance circulate in humans, animals and environment. Our findings stress the need to implement preventive and control measures for reducing the circulation of this potentially emerging public health threat.

Microbiological Profile of Fracture Related Infection at a UK Major Trauma Centre.

Fracture Related Infection (FRI) represents one of the biggest challenges for Trauma and Orthopaedic surgery. A better understanding of the microbiological profile should assist with decision-making and optimising outcomes. Our primary aim was to report on the microbiological profile of FRI cases treated over a six-year period at one of Europe's busiest trauma centres. Secondarily, we sought to correlate our findings with existing anti-microbiological protocols and report on diagnostic techniques employed in our practice. All adult cases of FRI treated in our institution between 2016 and 2021 were identified, retrospectively. We recorded patient demographics, diagnostic strategies, causative organisms and antibiotic susceptibilities. There were 330 infection episodes in 294 patients. A total of 463 potentially pathogenic organisms (78 different species) were identified from cultures, of which 57.2% were gram-positive and 39.7% gram-negative. Polymicrobial cultures were found in 33.6% of cases and no causative organism was found in 17.5%. The most prevalent organisms were Staphylococcus aureus (24.4%), coagulase-negative Staphylococci (14%), Pseudomonas aeruginosa (8.2%), Enterobacter species (7.8%) and Escherichia coli (6.9%). Resistant gram-positive organisms (methicillin resistant Staphylococcus aureus or vancomycin-resistant Enterococci) were implicated in 3.3% of infection episodes and resistant gram-negatives (extended-spectrum beta-lactamase, ampC or carbapenemase-producing bacteria) in 13.6%. The organisms cultured in 96.3% of infection episodes would have been covered by our empirical systemic antibiotic choice of teicoplanin and meropenem. To our knowledge, this is the largest reported single-centre cohort of FRIs from a major trauma centre. Our results demonstrate patterns in microbiological profiles that should serve to inform the decision-making process regarding antibiotic choices for both prophylaxis and treatment.

In Vitro Activity of Cefiderocol Against Carbapenem-Resistant Enterobacterales and Pseudomonas aeruginosa.

The objective of this study was to assess the susceptibility of cefiderocol against multidrug-resistant carbapenemase-producing and nonproducing bacteria. The panel comprised 182 isolates of the order Enterobacterales, and 40 strains of Pseudomonas aeruginosa. Antimicrobial susceptibility testing has been performed using broth microdilution method according to the European Committee on Antimicrobial Susceptibility Testing recommendations. Mass spectrometry matrix-assisted laser desorption/ionization-time of flight mass spectrometry and carbapenemase-producing test were used to verify the presence of carbapenemases in clinical isolates. The genetic expression of single carbapenemases (blaKPC, blaOXA-48, blaNDM, blaVIM, blaIMP, blaGES) was determined by real-time polymerase chain reaction. Cefiderocol exhibited a good activity against the majority of strains tested in this study. Altogether, growth of 81.9% (n = 149) strains of the order Enterobacterales and 77.5% (n = 31) of P. aeruginosa isolates were inhibited at minimal inhibitory concentration (MIC) ≤2 mg/L. Values MIC50/MIC90 were 0.5/8 mg/L for enterobacteria, and 1/8 mg/L for P. aeruginosa. One isolate (Klebsiella pneumoniae) harboring two carbapenemases (blaOXA-48, blaNDM) had cefiderocol MIC 0.5 mg/L. In enterobacteria resistant to cefiderocol, blaNDM carbapenemase prevailed (43.3%, n = 29), followed by blaOXA-48 (31.3%, n = 21) and blaKPC (4.5%, n = 3). blaIMP (n = 8) and blaVIM (n = 1) metallo-β-lactamases dominated in cefiderocol-resistant P. aeruginosa (n = 9) isolates. Very good susceptibility (100%) to this drug showed blaGES-positive strains of P. aeruginosa (n = 8) and isolates resistant to meropenem without confirmed carbapenemase gene (n = 10). In this study, cefiderocol demonstrated potent activity against important nosocomial pathogens, therefore, therapeutic options of this drug against multidrug-resistant bacteria should be considered.

Rapid Detection of Carbapenemase-Producing Multidrug-Resistant (MDR) Pathogens by Modified Carba NP Test in Ventilator-Associated Pneumonia (VAP) in Elderly Patients.

Background Ventilator-associated pneumonia (VAP) is defined as pneumonia that develops 48 hours or more after endotracheal intubation or tracheostomy and is brought on by infectious organisms that are not present or incubating during mechanical ventilation. Multidrug-resistant organisms originate primarily from the hospital environment and significantly contribute to ventilator-associated pneumonia. These organisms pose a severe threat, leading to a higher mortality rate due to their resistance to more potent antibiotics. Methods The study aims to assess the efficacy of the modified Carba NP test in detecting carbapenemase-producing bacteria in geriatric VAP patients. Results Forty (38 gram-negative and 2 gram-positive) pathogens were isolated from VAP patients. The isolates were identified using standard laboratory protocol; Acinetobacter spp. (n=16; 40% ), followed by Klebsiella pneumoniae (n=13; 32.5%), is the most common organism isolated. Seventeen (44.73%) were multi-drug resistant gram-negative bacteria. The carbapenemase producers were detected by the Kirby-Bauer disc diffusion method and compared with the modified Carba NP test with a turnaround time of 12-18 hrs in comparison to the disk diffusion test which requires additional 12hrs. Carbapenemase production was seen in 12 (70.59%) MDR isolates (7-Acinetobacter spp, 3-Klebsiella pneumonia, 1-Escherichia coli, and 1-Pseudomonas aeruginosa). Conclusion Modified Carba NP can be used as a rapid test to detect carbapenemase production, and it can replace the traditional disk diffusion method of detecting carbapenemase production. This test plays a crucial role in the management of critical patients by saving 12-18 hours to determine the most appropriate and effective antibiotic treatment. This timely decision is essential in preventing sepsis caused by localized infections.

Imipenem/funobactam (formerly XNW4107) in vivo pharmacodynamics against serine carbapenemase-producing Gram-negative bacteria: a novel modelling approach for time-dependent killing.

Imipenem/funobactam (formerly XNW4107) is a novel β-lactam/β-lactamase inhibitor with activity against MDR Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacterales strains. Using a neutropenic murine thigh infection model, we aimed to determine the pharmacokinetic/pharmacodynamic (PK/PD) index, relative to funobactam exposure, that correlated most closely with the in vivo efficacy of imipenem/funobactam combination and the magnitude of index required for efficacy against serine carbapenemase-producing clinical strains. Dose-fractionation was conducted against three strains. Imipenem human-simulated regimen (HSR, 500 mg q6h 1 h infusion) efficacy in combination with escalating funobactam exposures against seven A. baumannii, four P. aeruginosa and four Klebsiella pneumoniae (imipenem/funobactam MICs 0.25-16 mg/L) was assessed as 24 h change in log10cfu/thigh. Increased funobactam fractionation enhanced efficacy, indicating time-dependent killing. Changes in log10cfu/thigh versus %fT > MIC were poorly predictive of efficacy; bactericidal activity was observed at %fT > MIC = 0%. Across different threshold plasma funobactam concentrations (CTs), %fT > CT(1 mg/L) had the highest correlation with efficacy. Normalizing the %fT > CT = 1 mg/L index to the respective isolate imipenem/funobactam MIC ([%fT > CT]/MIC) allowed integration of the isolate's susceptibility, which further enhanced the correlation. Median (%fT > CT[1 mg/L])/MIC values associated with 1-log reductions were 9.82 and 9.90 for A. baumannii and P. aeruginosa, respectively. Median (%fT > CT[1 mg/L])/MIC associated with stasis was 55.73 for K. pneumoniae. Imipenem/funobactam 500/250 mg q6h 1 h infusion HSR produced >1-log kill against 6/7 A. baumannii, 4/4 P. aeruginosa and stasis against 4/4 K. pneumoniae. Imipenem/funobactam showed potent in vivo efficacy against serine carbapenemase-producers. The novel PK/PD index (%fT > CT)/MIC appeared to best describe in vivo activity.

Factors associated with non-carbapenemase mediated carbapenem resistance of Gram-negative bacteria: a retrospective case-control study

Infections with carbapenemase-producing Gram-negative bacteria are related to increased morbidity and mortality, yet little is known regarding infections caused by non-beta-lactamase mediated carbapenem-resistant bacteria. Our objective was to identify risk factors for, and the clinical impact of infections caused by carbapenem-resistant carbapenemase-negative Enterobacterales and Pseudomonas aeruginosa. This retrospective matched case-control study was performed at the University Hospital of Basel, Switzerland, in 2016. We focused on other resistance mechanisms by excluding laboratory-confirmed carbapenemase-positive cases. Carbapenem resistance was set as the primary endpoint, and important risk factors were investigated by conditional logistic regression. The clinical impact of carbapenem resistance was estimated using regression models containing the resistance indicator as explanatory factor and adjusting for potential confounders. Seventy-five cases of infections with carbapenem-resistant, carbapenemase-negative bacteria were identified and matched with 75 controls with carbapenem-susceptible infections. The matched data set was well-balanced regarding age, gender, and comorbidity. Duration of prior carbapenem treatment (OR 1.15, [1.01, 1.31]) correlated with resistance to carbapenems. Our study showed that patients with carbapenem-resistant bacteria stayed 1.59 times (CI [0.81, 3.14]) longer in an ICU. The analyzed dataset did not provide evidence for strong clinical implications of resistance to carbapenems or increased mortality. The duration of prior carbapenem treatment seems to be a strong risk factor for the development of carbapenem resistance. The higher risk for a longer ICU stay could be a consequence of a carbapenem resistance. In contrast to carbapenemase-producers, the clinical impact of carbapenamase-negative, carbapenem-resistant strains may be limited. Trial registration: The study design was prospectively approved by the local Ethics Commission on 10.08.2017 (EKNZ BASEC 2017-00222).

Epidemiology of patients harboring carbapenemase-producing bacteria and comparison with patients with detection of extended-spectrum beta-lactamase-producing Enterobacterales-A retrospective cohort study.

We evaluated the epidemiology of carbapenemase-producing bacteria (CPB) in Switzerland by comparing risk factors between patients colonized with CPB and patients colonized with extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE). This retrospective cohort study was conducted at the University Hospital Basel in Switzerland. Hospitalized patients with CPB in any sample between January 2008 and July 2019 were included. The ESBL-PE group consisted of hospitalized patients with detection of ESBL-PE from any sample between January 2016 and December 2018. Comparisons of risk factors for acquisition of CPB and ESBL-PE were performed by logistic regression. Inclusion criteria were met for 50 patients in the CPB group and 572 in the ESBL-PE group. In the CPB group, 62% had a travel history and 60% had been hospitalized abroad. When comparing the CPB group to the ESBL-PE group, hospitalization abroad (odds ratio [OR], 25.33; 95% confidence interval [CI], 11.07-57.98) and prior antibiotic therapy (OR, 4.76; 95% CI, 2.15-10.55) remained independently associated with CPB colonization. Hospitalization abroad (P < .001) and prior antibiotic therapy (P < .001) predicted CPB in the comparison of CPB with ESBL Escherichia coli, whereas hospitalization abroad was associated with CPB in comparison to ESBL Klebsiella pneumoniae. Although CPB still seem to be mainly imported from areas of higher endemicity, local acquisition of CPB is emerging, especially in patients with close and/or frequent contact with healthcare services. This trend resembles the epidemiology of ESBL K. pneumoniae, supporting mainly healthcare-associated transmission. Frequent evaluation of CPB epidemiology is required to improve detection of patients at risk of CPB carriage.

Longitudinal study of ESBL/AmpC-producing Enterobacterales strains sharing between cohabiting healthy companion animals and humans in Portugal and in the United Kingdom.

Extended-spectrum beta-lactamase (ESBL)- and plasmid-mediated cephalosporinase (AmpC)-producing Enterobacterales (ESBL/AmpC-E) are an increasing healthcare problem in both human and veterinary medicine. The aim of this study was to investigate the possible sharing of ESBL/AmpC-E strains between healthy companion animals and humans of the same household in Portugal (PT) and the United Kingdom (UK). In a prospective longitudinal study, between 2018 and 2020, faecal samples were collected from healthy dogs (n=90), cats (n=20) and their cohabiting humans (n=119) belonging to 41 PT and 44 UK households. Samples were screened for the presence of ESBL/AmpC-E and carbapenemase-producing bacteria. Clonal relatedness between animal and human strains was established by using REP-PCR fingerprinting method, followed by whole-genome sequencing (WGS) of selected strains. ESBL/AmpC-E strains were detected in companion animals (PT=12.7%, n=8/63; UK=8.5%, n=4/47) and humans (PT=20.7%, n=12/58; UK=6.6%, n=4/61) in at least one timepoint. REP-PCR identified paired multidrug-resistant ESBL/AmpC-producing Escherichia coli strains from companion animals and owners in two Portuguese households (4.8%) and one UK household (2.3%). WGS analysis of nine E. coli strains from these three households confirmed that interhost sharing occurred only between the two animal-human pairs from Portugal. Three shared strains were identified: one CTX-M-15-producing E. coli strain in a cat-human pair (O15-H33-ST93) and two CTX-M-15- and CTX-M-55/CMY-2-producing E. coli strains, in a dog-human pair (O8:H9-ST410 and O11:H25-ST457, respectively) at different timepoints. These E. coli clonal lineages are human pandemic, highlighting the role of companion animals living in close contact with humans in the dissemination and persistence of antimicrobial resistance in the household environment.