Deciphering mechanisms affecting cefepime-taniborbactam in vitro activity in carbapenemase-producing Enterobacterales and carbapenem-resistant Pseudomonas spp. isolates recovered during a surveillance study in Spain.

PURPOSE: To characterize the resistance mechanisms affecting the cefepime-taniborbactam combination in a collection of carbapenemase-producing Enterobacterales (CPE) and carbapenem-resistant Pseudomonas spp. (predominantly P. aeruginosa; CRPA) clinical isolates. METHODS: CPE (n = 247) and CRPA (n = 170) isolates were prospectively collected from patients admitted to 8 Spanish hospitals. Susceptibility to cefepime-taniborbactam and comparators was determined by broth microdilution. Cefepime-taniborbactam was the most active agent, inhibiting 97.6% of CPE and 67.1% of CRPA (MICs ≤ 8/4 mg/L). All isolates with cefepime-taniborbactam MIC > 8/4 mg/L (5 CPE and 52 CRPA) and a subset with MIC ≤ 8/4 mg/L (23 CPE and 24 CRPA) were characterized by whole genome sequencing. RESULTS: A reduced cefepime-taniborbactam activity was found in two KPC-ST307-Klebsiella pneumoniae isolates with altered porins [KPC-62-K. pneumoniae (OmpA, OmpR/EnvZ), KPC-150-K. pneumoniae (OmpK35, OmpK36)] and one each ST133-VIM-1-Enterobacter hormaechei with altered OmpD, OmpR, and OmpC; IMP-8-ST24-Enterobacter asburiae; and NDM-5-Escherichia coli with an YRIN-inserted PBP3 and a mutated PBP2. Among the P. aeruginosa (68/76), elevated cefepime-taniborbactam MICs were mostly associated with GES-5-ST235, OXA-2+VIM-2-ST235, and OXA-2+VIM-20-ST175 isolates also carrying mutations in PBP3, efflux pump (mexR, mexZ) and AmpC (mpl) regulators, and non-carbapenemase-ST175 isolates with AmpD-T139M and PBP3-R504C mutations. Overall, accumulation of these mutations was frequently detected among non-carbapenemase producers. CONCLUSIONS: The reduced cefepime-taniborbactam activity among the minority of isolates with elevated cefepime-taniborbactam MICs is not only due to IMP carbapenemases but also to the accumulation of multiple resistance mechanisms, including PBP and porin mutations in CPE and chromosomal mutations leading to efflux pumps up-regulation, AmpC overexpression, and PBP modifications in P. aeruginosa.

Corrigendum: CARB-ES-19 multicenter study of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli from all Spanish provinces reveals interregional spread of high-risk clones such as ST307/OXA-48 and ST512/KPC-3.

[This corrects the article DOI: 10.3389/fmicb.2022.918362.].

The CARBA-MAP study: national mapping of carbapenemases in Spain (2014-2018).

Introduction: Infections caused by carbapenem-resistant Enterobacterales (CRE) and carbapenem-resistant Pseudomonas aeruginosa, including isolates producing acquired carbapenemases, constitute a prevalent health problem worldwide. The primary objective of this study was to determine the distribution of the different carbapenemases among carbapenemase-producing Enterobacterales (CPE, specifically Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae complex, and Klebsiella aerogenes) and carbapenemase-producing P. aeruginosa (CPPA) in Spain from January 2014 to December 2018. Methods: A national, retrospective, cross-sectional multicenter study was performed. The study included the first isolate per patient and year obtained from clinical samples and obtained for diagnosis of infection in hospitalized patients. A structured questionnaire was completed by the participating centers using the REDCap platform, and results were analyzed using IBM SPSS Statistics 29.0.0. Results: A total of 2,704 carbapenemase-producing microorganisms were included, for which the type of carbapenemase was determined in 2692 cases: 2280 CPE (84.7%) and 412 CPPA (15.3%), most often using molecular methods and immunochromatographic assays. Globally, the most frequent types of carbapenemase in Enterobacterales and P. aeruginosa were OXA-48-like, alone or in combination with other enzymes (1,523 cases, 66.8%) and VIM (365 cases, 88.6%), respectively. Among Enterobacterales, carbapenemase-producing K. pneumoniae was reported in 1821 cases (79.9%), followed by E. cloacae complex in 334 cases (14.6%). In Enterobacterales, KPC is mainly present in the South and South-East regions of Spain and OXA-48-like in the rest of the country. Regarding P. aeruginosa, VIM is widely distributed all over the country. Globally, an increasing percentage of OXA-48-like enzymes was observed from 2014 to 2017. KPC enzymes were more frequent in 2017-2018 compared to 2014-2016. Discussion: Data from this study help to understand the situation and evolution of the main species of CPE and CPPA in Spain, with practical implications for control and optimal treatment of infections caused by these multi-drug resistant organisms.

CARB-ES-19 Multicenter Study of Carbapenemase-Producing Klebsiella pneumoniae and Escherichia coli From All Spanish Provinces Reveals Interregional Spread of High-Risk Clones Such as ST307/OXA-48 and ST512/KPC-3.

Objectives: CARB-ES-19 is a comprehensive, multicenter, nationwide study integrating whole-genome sequencing (WGS) in the surveillance of carbapenemase-producing K. pneumoniae (CP-Kpn) and E. coli (CP-Eco) to determine their incidence, geographical distribution, phylogeny, and resistance mechanisms in Spain. Methods: In total, 71 hospitals, representing all 50 Spanish provinces, collected the first 10 isolates per hospital (February to May 2019); CPE isolates were first identified according to EUCAST (meropenem MIC > 0.12 mg/L with immunochromatography, colorimetric tests, carbapenem inactivation, or carbapenem hydrolysis with MALDI-TOF). Prevalence and incidence were calculated according to population denominators. Antibiotic susceptibility testing was performed using the microdilution method (EUCAST). All 403 isolates collected were sequenced for high-resolution single-nucleotide polymorphism (SNP) typing, core genome multilocus sequence typing (cgMLST), and resistome analysis. Results: In total, 377 (93.5%) CP-Kpn and 26 (6.5%) CP-Eco isolates were collected from 62 (87.3%) hospitals in 46 (92%) provinces. CP-Kpn was more prevalent in the blood (5.8%, 50/853) than in the urine (1.4%, 201/14,464). The cumulative incidence for both CP-Kpn and CP-Eco was 0.05 per 100 admitted patients. The main carbapenemase genes identified in CP-Kpn were bla OXA-48 (263/377), bla KPC-3 (62/377), bla VIM-1 (28/377), and bla NDM-1 (12/377). All isolates were susceptible to at least two antibiotics. Interregional dissemination of eight high-risk CP-Kpn clones was detected, mainly ST307/OXA-48 (16.4%), ST11/OXA-48 (16.4%), and ST512-ST258/KPC (13.8%). ST512/KPC and ST15/OXA-48 were the most frequent bacteremia-causative clones. The average number of acquired resistance genes was higher in CP-Kpn (7.9) than in CP-Eco (5.5). Conclusion: This study serves as a first step toward WGS integration in the surveillance of carbapenemase-producing Enterobacterales in Spain. We detected important epidemiological changes, including increased CP-Kpn and CP-Eco prevalence and incidence compared to previous studies, wide interregional dissemination, and increased dissemination of high-risk clones, such as ST307/OXA-48 and ST512/KPC-3.

Association between Timing of Colonization and Risk of Developing Klebsiella pneumoniae Carbapenemase-Producing K. pneumoniae Infection in Hospitalized Patients.

Colonization by KPC-producing Klebsiella pneumoniae (KPC-Kp) is associated with the risk of developing KPC-Kp infection. The impact of the time elapsed since a patient becomes colonized on this risk is not well known. An observational, prospective, longitudinal cohort study of colonized patients undergoing active rectal culture screening to rule out KPC-Kp colonization (July 2012 to November 2017). Patients with a positive culture at inclusion (colonized at start of follow-up) and those with a negative culture at inclusion who became colonized within 90 days (colonized during follow-up) were included in the analysis. CART analysis was used to dichotomize variables according to their association with infection. Kaplan-Meier infection-free survival curves and the log-rank test were used for group comparisons. Logistic regression was used to identify variables associated with KPC-Kp infection. Among 1310 patients included, 166 were colonized at the end of follow-up. Forty-seven out of 118 patients colonized at start of follow-up developed infection (39.8%) versus 31 out of 48 patients colonized during follow-up (64.6%; P = 0.006). Variables associated with KPC-Kp infection in the logistic regression analysis were: colonization detection during follow-up (OR, 2.74; 95% CI, 1.07 to 7.04; P = 0.03), Giannella risk score (OR, 1.51; 95% CI, 1.32 to 1.73; P < 0.001), high-risk ward (OR, 4.77; 95% CI, 1.61 to 14.10; P = 0.005) and urological manipulation after admission (OR, 3.69; 95% CI, 1.08 to 12.60; P = 0.04). In 25 out of 31 patients (80.6%) colonized during follow-up who developed KPC-Kp infection, infection appeared within 15 days after colonization. The risk of KPC-Kp infection was higher when colonization is recently acquired during hospitalization. In this prospective study, we concluded that the timing of colonization was a factor to assess when considering empirical treatment for suspected KPC-Kp infection and prophylaxis or infection control. IMPORTANCE In this study, it was confirmed that patients who became colonized during hospitalization had a higher risk of developing KPC-Kp infection than hospitalized patients who were already colonized at the start of follow-up. Besides, the risk of infection in the group of patients who became colonized during follow-up was greater in the first weeks immediately after colonization was confirmed. Our findings support the need for designing preventive strategies for patients at the highest risk of infection development, including those admitted in high-risk hospital wards and those undergoing urological procedures.

Impact of ceftazidime/avibactam versus best available therapy on mortality from infections caused by carbapenemase-producing Enterobacterales (CAVICOR study).

BACKGROUND: Infections caused by carbapenemase-producing Enterobacterales (CPE) are not well represented in pivotal trials with ceftazidime/avibactam. The best strategy for the treatment of these infections is unknown. METHODS: We conducted a multicentre retrospective observational study of patients who received ≥48 h of ceftazidime/avibactam or best available therapy (BAT) for documented CPE infections. The primary outcome was 30 day crude mortality. Secondary outcomes were 21 day clinical response and microbiological response. A multivariate logistic regression model was used to identify factors predictive of 30 day crude mortality. A propensity score to receive treatment with ceftazidime/avibactam was used as a covariate in the analysis. RESULTS: The cohort included 339 patients with CPE infections. Ceftazidime/avibactam treatment was used in 189 (55.8%) patients and 150 (44.2%) received BAT at a median of 2 days after diagnosis of infection. In multivariate analysis, ceftazidime/avibactam treatment was associated with survival (OR 0.41, 95% CI 0.20-0.80; P = 0.01), whereas INCREMENT-CPE scores of >7 points (OR 2.57, 95% CI 1.18-1.5.58; P = 0.01) and SOFA score (OR 1.20, 95% CI 1.08-1.34; P = 0.001) were associated with higher mortality. In patients with INCREMENT-CPE scores of >7 points, ceftazidime/avibactam treatment was associated with lower mortality compared with BAT (16/73, 21.9% versus 23/49, 46.9%; P = 0.004). Ceftazidime/avibactam was also an independent factor of 21 day clinical response (OR 2.43, 95% CI 1.16-5.12; P = 0.02) and microbiological eradication (OR 0.40, 95% CI 0.18-0.85; P = 0.02). CONCLUSIONS: Ceftazidime/avibactam is an effective alternative for the treatment of CPE infections, especially in patients with INCREMENT-CPE scores of >7 points. A randomized controlled trial should confirm these findings.

In Vitro Activity of Cefepime-Taniborbactam against Carbapenemase-Producing Enterobacterales and Pseudomonas aeruginosa Isolates Recovered in Spain.

Novel ß-lactam-ß-lactamase inhibitor combinations currently approved for clinical use are poorly active against metallo-ß-lactamase (MBL)-producing strains. We evaluated the in vitro activity of cefepime-taniborbactam (FTB [formerly cefepime-VNRX-5133]) and comparator agents against carbapenemase-producing Enterobacterales (n = 247) and carbapenem-resistant Pseudomonas species (n = 170) clinical isolates prospectively collected from different clinical origins in patients admitted to 8 Spanish hospitals. FTB was the most active agent in both Enterobacterales (97.6% MICFTB, ≤8/4 mg/L) and Pseudomonas (67.1% MICFTB, ≤8/4 mg/L) populations. The MICFTB was >8 mg/L in 6/247 (2.4%) Enterobacterales isolates (3 KPC-producing Klebsiella pneumoniae isolates, 1 VIM-producing Enterobacter cloacae isolate, 1 IMP-producing E. cloacae isolate, and 1 NDM-producing Escherichia coli isolate) and in 56/170 (32.9%) Pseudomonas isolates, 19 of them carbapenemase producers (15 producers of VIM, 2 of GES, 1 of GES+VIM, and 1 of GES+KPC). Against the Enterobacterales isolates with meropenem MICs of >2 mg/L (138/247), FTB was the most active agent against both serine-ß-lactamases (107/138) and MBL producers (31/138) (97.2 and 93.5% MICFTB, ≤8/4 mg/L, respectively), whereas the activity of comparators was reduced, particularly against the MBL producers (ceftazidime-avibactam, 94.4 and 12.9%, meropenem-vaborbactam, 85.0 and 64.5%, imipenem-relebactam, 76.6 and 9.7%, ceftolozane-tazobactam, 1.9 and 0%, and piperacillin-tazobactam, 0 and 0%, respectively). Among the meropenem-resistant Pseudomonas isolates (163/170; MIC, >2 mg/L), the activities of FTB against serine-ß-lactamase (35/163) and MBL (43/163) producers were 88.6 and 65.1%, respectively, whereas the susceptibilities of comparators were as follows: ceftazidime-avibactam, 88.5 and 16.0%, meropenem-vaborbactam, 8.5 and 7.0%, imipenem-relebactam, 2.9 and 2.3%, ceftolozane-tazobactam, 0 and 2.3%, and piperacillin-tazobactam, 0 and 0%, respectively. Microbiological results suggest FTB as a potential therapeutic option in patients infected with carbapenemase-producing Enterobacterales and carbapenem-resistant Pseudomonas isolates, including MBL producers.

Association between rectal colonisation by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae and mortality: a prospective, observational study.

OBJECTIVES: We evaluated the association of Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) rectal colonisation with crude mortality and whether this association is independent of the risk of KPC-Kp infection. METHODS: This was a prospective cohort study of patients followed-up 90 days after a study of rectal colonisation. Cox regression was used to study the variables associated with crude mortality. Sensitivity analyses for 90-day crude mortality in different subcohorts were performed. RESULTS: A total of 1244 patients (1078 non-colonised and 166 colonised) were included. None of the non-colonised patients and 78 (47.0%) of the colonised patients developed KPC-Kp infection. The 90-day crude mortality was 18.0% (194/1078) in non-colonised patients and 41.6% (69/166) in colonised patients. Rectal colonisation was not associated with crude mortality [hazard ratio (HR) = 1.03, 95% confidence interval (CI) 0.69-1.54; P = 0.85] when the model was adjusted for severe KPC-Kp infection [INCREMENT-CPE score (ICS) > 7]. KPC-Kp infection with ICS > 7 was associated with an increased risk of all-cause mortality (HR = 2.21, 95% CI 1.35-3.63; P = 0.002). In the sensitivity analyses, KPC-Kp colonisation was not associated with mortality in any of the analysed subcohorts, including patients who did not develop KPC-Kp infection (HR = 0.93, 95% CI 0.60-1.43; P = 0.74). CONCLUSION: KPC-Kp rectal colonisation was not associated with crude mortality. Mortality increased when colonised patients developed severe KPC-Kp infection (ICS > 7). Rectal colonisation was a necessary although insufficient condition to die from a KPC-Kp infection.

Molecular characterization of multidrug resistant Enterobacterales strains isolated from liver and kidney transplant recipients in Spain.

The objective of this study was to analyse the mechanisms of resistance to carbapenems and other extended-spectrum-ß-lactams and to determine the genetic relatedness of multidrug-resistant Enterobacterales (MDR-E) causing colonization or infection in solid-organ transplantation (SOT) recipients. Prospective cohort study in kidney (n = 142), liver (n = 98) or kidney/pancreas (n = 7) transplant recipients between 2014 and 2018 in seven Spanish hospitals. We included 531 MDR-E isolates from rectal swabs obtained before transplantation and weekly for 4-6 weeks after the procedure and 10 MDR-E from clinical samples related to an infection. Overall, 46.2% Escherichia coli, 35.3% Klebsiella pneumoniae, 6.5% Enterobacter cloacae, 6.3% Citrobacter freundii and 5.7% other species were isolated. The number of patients with MDR-E colonization post-transplantation (176; 71.3%) was 2.5-fold the number of patients colonized pre-transplantation (71; 28.7%). Extended-spectrum ß-lactamases (ESBLs) and carbapenemases were detected in 78.0% and 21.1% of MDR-E isolates respectively. In nine of the 247 (3.6%) transplant patients, the microorganism causing an infection was the same strain previously cultured from surveillance rectal swabs. In our study we have observed a low rate of MDR-E infection in colonized patients 4-6 weeks post-transplantation. E. coli producing blaCTX-M-G1 and K. pneumoniae harbouring blaOXA-48 alone or with blaCTX-M-G1 were the most prevalent MDR-E colonization strains in SOT recipients.

Impact of an Antimicrobial Stewardship Program on the Incidence of Carbapenem Resistant Gram-Negative Bacilli: An Interrupted Time-Series Analysis.

Carbapenem-resistant Gram-negative bacilli (CR-GNB) are a critical public health threat, and carbapenem use contributes to their spread. Antimicrobial stewardship programs (ASPs) have proven successful in reducing antimicrobial use. However, evidence on the impact of carbapenem resistance remains unclear. We evaluated the impact of a multifaceted ASP on carbapenem use and incidence of CR-GNB in a high-endemic hospital. An interrupted time-series analysis was conducted one year before and two years after starting the ASP to assess carbapenem consumption, CR-GNB incidence, death rates of sentinel events, and other variables potentially related to CR-GNB incidence. An intense reduction in carbapenem consumption occurred after starting the intervention and was sustained two years later (relative effect -83.51%; 95% CI -87.23 to -79.79). The incidence density of CR-GNB decreased by -0.915 cases per 1000 occupied bed days (95% CI -1.743 to -0.087). This effect was especially marked in CR-Klebsiella pneumoniae and CR-Escherichia coli, reversing the pre-intervention upward trend and leading to a relative reduction of -91.15% (95% CI -105.53 to -76.76) and -89.93% (95% CI -107.03 to -72.83), respectively, two years after starting the program. Death rates did not change. This ASP contributed to decreasing CR-GNB incidence through a sustained reduction in antibiotic use without increasing mortality rates.

Adherence to Human Colon Cells by Multidrug Resistant Enterobacterales Strains Isolated From Solid Organ Transplant Recipients With a Focus on Citrobacter freundii.

Enterobacteria species are common causes of hospital-acquired infections, which are associated with high morbidity and mortality rates. Immunocompromised patients such as solid organ transplant (SOT) recipients are especially at risk because they are frequently exposed to antibiotics in the course of their treatments. In this work, we used a collection of 106 Escherichia coli, 78 Klebsiella pneumoniae, 25 Enterobacter spp., and 24 Citrobacter spp. multidrug resistant strains isolated from transplant patients (hepatic, renal or renal/pancreatic) in order to examine their ability to adhere in vitro to HT-29 human colon cells, and to determine if some adhesive characteristics are associated with prevalence and persistence of these strains. A total of 33 E. coli (31%), 21 K. pneumoniae (27%), 7 Enterobacter spp. (28%), and 5 Citrobacter spp. (21%), adhered to the colon epithelial cells. Two main adherence patterns were observed in the four species analyzed, diffuse adherence, and aggregative adherence. Under transmission electronic microscopy (TEM), most bacteria lacked visible fimbria on their surface, despite their strong adherence to epithelial cells. None of the strains studied was able to induce any cytotoxic effect on HT-29 cells although some of them strongly colonizing both cells and glass coverslips at high density. Some of the strains failed to adhere to the epithelial cells but adhered strongly to the cover-slide, which shows that microscopy studies are mandatory to elucidate the adherence of bacteria to epithelial cells in vitro, and that quantitative assays using colony forming unit (CFUs) counting need to be supplemented with pictures to determine definitively if a bacterial strain adheres or not to animal cells in vitro. We report here, for the first time, the aggregative adherence pattern of two multidrug resistant (MDR) Citrobacter freundii strains isolated from human patients; importantly, biofilm formation in Citrobacter is totally dependent on the temperature; strong biofilms were formed at room temperature (RT) but not at 37°C, which can play an important role in the colonization of hospital surfaces. In conclusion, our results show that there is a great variety of adhesion phenotypes in multidrug-resistant strains that colonize transplanted patients.

Use of carbapenems in the combined treatment of emerging ceftazidime/avibactam-resistant and carbapenem-susceptible KPC-producing Klebsiella pneumoniae infections: Report of a case and review of the literature.

OBJECTIVES: To describe the case of a patient with infection due to a KPC-producing Klebsiella pneumoniae (K. pneumoniae) isolate developing ceftazidime-avibactam resistance with restored carbapenem susceptibility during ceftazidime-avibactam therapy. To review the clinical/microbiological cure and survival rates using carbapenems in other similar case reports and case series. PATIENTS AND METHODS: A patient with an intra-abdominal infection due to K. pneumoniae producing the KPC-48 variant (L169P-A172T) (resistant to ceftazidime/avibactam and susceptible to carbapenems) who was treated with imipenem-cilastatin in combination with tigecycline and gentamicin. The literature was reviewed in order to summarise the in vivo (clinical/microbiological cure and survival rate) use of carbapenems in this emerging scenario. RESULTS: The patient was successfully treated with the indicated regimen. In other reported cases (mostly with pneumonia) all-cause mortality was 50% and clinical cure was 62.5%. Meropenem-vaborbactam has been successful used in an additional case. CONCLUSIONS: A carbapenem-based regimen of combination therapy seems to be an option for treating patients infected with K. pneumoniae resistant to ceftazidime/avibactam and susceptible to carbapenems, at least when the risk of mortality is low.

Microbiological diagnosis of catheter-related infections / Diagnóstico microbiológico de las infecciones asociadas a catéteres intravasculares

This revision describes in detail the different diagnostic techniques of catheter-related infection, both in terms of catheter removal and preservation. Culture techniques based on catheter withdrawal are classified depending on the detection of extraluminal and/or intraluminal colonization, and new methodologies are described. In general, the most important recommendations are: (a) do not send for culture catheter tips without suspicion of infection, (b) Maki's technique is the standard for detecting extraluminal colonization, (c) take 2 pairs of peripheral blood cultures before starting antibiotic treatment, (d) use skin and connections/connectors cultures for the conservative diagnosis due to their high negative predictive value (Gram and culture), and (e) take differential quantitative blood cultures though all catheter lumens and through a peripheral vein

Esta revisión describe con detalle las diferentes técnicas diagnósticas de infección relacionada con el catéter, tanto con la retirada como con la conservación del mismo. Las técnicas de cultivo basadas en la retirada del catéter se clasifican en base a la detección de colonización extraluminal, intraluminal, o ambas, asimismo, se describen nuevas metodologías. De forma general, las recomendaciones más importantes son: a) no enviar para cultivo puntas de catéter retiradas sin sospecha de infección, b) la técnica de Maki es el estándar válido de detección de colonización extraluminal, c) tomar 2 parejas de hemocultivos de sangre periférica antes de iniciar tratamiento antibiótico, d) utilizar cultivos de piel y conexiones/conectores para el diagnóstico conservador por su alto valor predictivo negativo (Gram y cultivo), y e) extraer hemocultivos cuantitativos diferenciales por todas las luces del catéter y por vena periférica

External validation of the INCREMENT-CPE mortality score in a carbapenem-resistant Klebsiella pneumoniae bacteraemia cohort: the prognostic significance of colistin resistance.

External validation of the INCREMENT-CPE risk score (ICS) for 30-day all-cause mortality is needed. There is also scarce information about whether colistin resistance influences the prognosis of carbapenem-resistant Klebsiella pneumoniae (CRKp) bacteraemia. In this study, the ability of ICS to predict all-cause mortality in the KAPECOR cohort was calculated using the area under the receiver operating characteristic (AUROC) curve. The association of colistin resistance with mortality was studied. The ICS showed an AUROC curve of 0.77 (95% CI 0.68-0.86). A cut-off of 8 points showed 96.8% sensitivity and 50.7% specificity. Mortality of low-risk patients was not different in those treated with monotherapy versus combination therapy. However, mortality of high-risk patients treated with combination therapy (37.8%) was significantly lower than in those treated with monotherapy (68.4%) (P = 0.008). To study the prognostic significance of colistin resistance, 83 selected cases of bacteraemia due to colistin-susceptible CRKp were obtained from the INCREMENT cohort for comparison. Colistin resistance could not be shown to be associated with higher mortality in either the high-risk ICS group [adjusted odds ratio (aOR) = 1.56, 95% CI 0.69-3.33; P = 0.29] or in 37 ICS-matched pairs (aOR = 1.38, 95% CI 0.55-3.42; P = 0.49), or in a sensitivity analysis including only KPC isolates (aOR = 1.81, 95% CI 0.73-4.57; P = 0.20), but the precision of estimates was low. These results validate ICS for all-cause mortality and to optimise targeted therapy for CRKp bacteraemia. Colistin resistance was not clearly associated with increased mortality.

Combination of Coral UTI ScreenTM system, gram-stain and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for diagnosis of urinary tract infections directly from urine samples.

This study proposes an algorithm for microbiological diagnosis of urinary tract infections based on screening by luminometry and Gram-stain, followed by identification by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Positive urine samples detected with the luminometry screening Coral UTI ScreenTM system underwent Gram staining and identification of the causative organism was performed by MALDI-TOF Microflex LT mass spectrometer (Bruker Daltonics, Germany). Subsequently, the results were compared with those of conventional culture identification using WIDER MIC/id system (Francisco Soria Melguizo SA, Spain). Considering the conventional approach as the gold standard, the proposed algorithm presented both a high specificity (98.1%) and a positive likelihood ratio of 37.42. The implementation of this algorithm would allow diagnosis of urinary tract infection in less than an hour in 92.4% of positive samples. This combination of techniques would be useful particularly for patients with severe UTI, pyelonephritis or urinary sepsis.

Microbiological diagnosis of catheter-related infections.

This revision describes in detail the different diagnostic techniques of catheter-related infection, both in terms of catheter removal and preservation. Culture techniques based on catheter withdrawal are classified depending on the detection of extraluminal and/or intraluminal colonization, and new methodologies are described. In general, the most important recommendations are: (a) do not send for culture catheter tips without suspicion of infection, (b) Maki's technique is the standard for detecting extraluminal colonization, (c) take 2 pairs of peripheral blood cultures before starting antibiotic treatment, (d) use skin and connections/connectors cultures for the conservative diagnosis due to their high negative predictive value (Gram and culture), and (e) take differential quantitative blood cultures though all catheter lumens and through a peripheral vein.

Activity of ceftazidime-avibactam against carbapenemase-producing Enterobacteriaceae from urine specimens obtained during the infection-carbapenem resistance evaluation surveillance trial (iCREST) in Spain.

The increasing rates of carbapenemase-producing Enterobacteriaceae (CPE) represent an important threat to health care systems and treatment of CPE infections is a challenge. The aim of the infection-carbapenem resistance evaluation surveillance trial (iCREST) was to determinate the prevalence of CPE in urine specimens in Spain and to evaluate the in vitro activity of ceftazidime-avibactam. Urine specimens (n = 11 826) were included and activity of ceftazidime-avibactam and comparators were investigated by broth microdilution in CPE. Carbapenemases were characterised by polymerase chain reaction (PCR) and sequencing as well as by whole genome sequencing (WGS). Overall prevalence of CPE was 1.6%. OXA-48 was the most prevalent (86.8%), followed by KPC (6.9%), VIM (4.8%), NDM (1.1%) and IMP (0.6%) carbapenemases. Klebsiella pneumoniae was the most common carbapenemase producer (87.8%). An uncommon carbapenemase type (IMP-8) in Spain was identify by WGS in an Enterobacter cloacae isolate, reinforcing the utility of surveillance programmes as effectives tools to detect unexpected genes that encode antimicrobial resistance. Ceftazidime-avibactam showed 100% susceptibility in KPC and OXA-48 producers and the rates of susceptibility in CPE non-susceptible to ceftazidime or meropenem were 92.1% and 96.9%, respectively. Ceftazidime-avibactam could be considered an adequate treatment option for urinary tract infections caused by KPC and OXA-48 producers.

Risks of Infection and Mortality Among Patients Colonized With Klebsiella pneumoniae Carbapenemase-Producing K. pneumoniae: Validation of Scores and Proposal for Management.

Background: The management and indication of empiric treatment in Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp)-colonized patients should be improved. Methods: A prospective cohort of 94 patients colonized by KPC-Kp was followed for 90 days to validate (i) the Giannella risk score (GRS) to predict the development of any type of KPC-Kp infection and (ii) the INCREMENT-CPE score (ICS) to predict 30-day mortality in patients with infection. Both scores were combined to recommend appropriate empiric treatment. The predictive ability of the scores was measured by calculating the area under the receiver operating characteristic (AUROC) curve. Results: The GRS showed an AUROC curve for infection due to KPC-Kp of 0.92 (95% confidence interval [CI], .87-.98). The optimal cutoff point was fixed at <7 and ≥7 (92.9% sensitivity, 84.8% specificity); infection developed in 6.3% patients in the 0-6 GRS group and in 84.8% patient in the ≥7 GRS group. According to the ICS, the severity of the infection was also significantly higher in the ≥7 GRS group. The ICS showed an AUROC of 0.78 (95% CI, .65-.91) for 30-day all-cause mortality among patients with infection. A classification and regression tree analysis confirmed the GRS cutoff point at 7, and selected ≥12 points to predict a KPC-Kp infection with a high ICS. Conclusions: Our results validate the GRS and ICS for indicating empiric therapy in KPC-Kp-colonized patients.

Mortality Associated with Bacteremia Due to Colistin-Resistant Klebsiella pneumoniae with High-Level Meropenem Resistance: Importance of Combination Therapy without Colistin and Carbapenems.

Combination therapy including colistin and a carbapenem has been found to be associated with lower mortality in the treatment of bloodstream infections (BSI) due to KPC-producing Klebsiella pneumoniae when the isolates show a meropenem or imipenem MIC of <16 mg/liter. However, the optimal treatment of BSI caused by colistin- and high-level carbapenem-resistant KPC-producing K. pneumoniae is unknown. A prospective cohort study including episodes of bacteremia caused by colistin-resistant and high-level meropenem-resistant (MIC ≥ 64 mg/liter) KPC-producing K. pneumoniae diagnosed from July 2012 to February 2016 was performed. The impact of combination therapy on crude 30-day mortality was analyzed by Cox regression using a propensity score as a covariate to control for indication bias and in an inverse probability of treatment weighting (IPTW) cohort. The study sample comprised 104 patients, of which 32 (30.8%) received targeted monotherapy and 72 (69.2%) received targeted combination therapy; none of them received either colistin or a carbapenem. The 30-day crude mortality rate was 30.8% (43.8% in patients treated with monotherapy and 25% in patients receiving combination therapy). In the Cox regression analysis, 30-day mortality was independently associated with septic shock at BSI onset (hazard ratio [HR], 6.03; 95% confidence interval [CI], 1.65 to 21.9; P = 0.006) and admission to the critical care unit (HR, 2.87; 95% CI, 0.99 to 8.27; P = 0.05). Targeted combination therapy was associated with lower mortality only in patients with septic shock (HR, 0.14; 95% CI, 0.03 to 0.67; P = 0.01). These results were confirmed in the Cox regression analysis of the IPTW cohort. Combination therapy is associated with reduced mortality in patients with bacteremia due to colistin-resistant KPC-producing K. pneumoniae with high-level carbapenem resistance in patients with septic shock.

Oral decontamination with aminoglycosides is associated with lower risk of mortality and infections in high-risk patients colonized with colistin-resistant, KPC-producing Klebsiella pneumoniae.

OBJECTIVES: Invasive infections caused by KPC-producing Klebsiella pneumoniae (KPCKP) are associated with very high mortality. Because infection is usually preceded by rectal colonization, we investigated if decolonization therapy (DT) with aminoglycosides had a protective effect in selected patients. METHODS: Patients with rectal colonization by colistin-resistant KPCKP who were at high risk of developing infection (because of neutropenia, surgery, previous recurrent KPCKP infections or multiple comorbidities) were followed for 180 days. Cox regression analysis including a propensity score was used to investigate the impact of the use of two intestinal decolonization regimens with oral aminoglycosides (gentamicin and neomycin/streptomycin) on mortality, risk of KPCKP infections and microbiological success. The study was registered with ClinicalTrials.gov (NCT02604849). RESULTS: The study sample comprised 77 colonized patients, of which 44 (57.1%) received DT. At 180 days of follow-up, decolonization was associated with a lower risk of mortality in multivariate analyses (HR 0.18; 95% CI 0.06-0.55) and a lower risk of KPCKP infections (HR 0.14; 95% CI 0.02-0.83) and increased microbiological success (HR 4.06; 95% CI 1.06-15.6). Specifically, gentamicin oral therapy was associated with a lower risk of crude mortality (HR 0.15; 95% CI 0.04-0.54), a lower risk of KPCKP infections (HR 0.86; 95% CI 0.008-0.94) and increased microbiological response at 180 days of follow-up (HR 5.67; 95% CI 1.33-24.1). Neomycin/streptomycin therapy was only associated with a lower risk of crude mortality (HR 0.22; 95% CI 0.06-0.9). CONCLUSIONS: Intestinal decolonization with aminoglycosides is associated with a reduction in crude mortality and KPCKP infections at 180 days after initiating treatment.