Evaluation of the in vitro activity of WCK 5222 (cefepime/zidebactam) and currently available combination therapies against single- and double-carbapenemase producing Enterobacteriaceae: Expanding the zone of hope.

Cefepime/zidebactam (WCK 5222) is a ß-lactam/ß-lactam enhancer antibiotic designed to retain in vitro activity against Enterobacteriaceae that simultaneously produce metallo-ß-lactamase (MBL) and serine-ß-lactamase (SBL). Aztreonam (ATM) plus ceftazidime/avibactam (CZA) or meropenem/vaborbactam (M/V) is an attractive option for coverage of such strains, but clinical laboratories are not equipped to distinguish which is the more potent regimen to inform treatment decisions. We evaluated Enterobacteriaceae that expressed MBL and ≥1 SBL (n=15) using gradient diffusion strip (GDS) methods to (1) determine the minimum inhibitory concentration (MIC) of WCK 5222 and (2) compare the in vitro potency of CZA+ATM vs. M/V+ATM. All isolates were non-susceptible to ATM, CZA, and M/V and were inhibited by WCK 5222 at cefepime concentrations ≥2 log2 dilutions below the susceptible-dose dependent breakpoint of 8 mg/L (MIC50/90, 1/2 mg/L). Activity of CZA+ATM vs. M/V+ATM was compared using the zone of hope (ZOH) product, quantitated by multiplying the length (in mm) of inhibited growth adjacent to each GDS from the point of intersection. The median (interquartile range) ZOH product for CZA+ATM and M/V+ATM was 75.4 (62.8-93.7) and 23.5 (14.1-60.4), respectively (P=0.002). In strains with one carbapenemase (the MBL), the median ZOH products were not statistically different, but in strains with an OXA-type carbapenemase (n=6), the median product for CZA+ATM and M/V+ATM was 78.1 and 20.7, respectively (P=0.004). Thus, CZA+ATM may offer enhanced coverage over M/V+ATM of Enterobacteriaceae co-expressing MBL and SBL. Further preclinical in vivo evaluations of WCK 5222 monotherapy are warranted.

Eravacycline: a new treatment option for complicated intra-abdominal infections in the age of multidrug resistance.

Aim: Recently approved for use in complicated intra-abdominal infection, eravacycline is a novel fluorocycline with broad spectrum of activity against resistant Gram-negative pathogens. This manuscript is a pooled analysis of two Phase III trials. Clinical efficacy: Clinical cure rates were 86.8% for eravacycline versus 87.6% for ertapenem, and 90.8% for eravacycline versus 91.2% for meropenem in the Intent to Treat (micro-ITT) populations, and 87.0% for eravacycline versus 88.8% ertapenem, and 92.4 versus 91.6% for meropenem in the Modified Intent to Treat (MITT) populations. Safety: Eravacycline is well tolerated, with lower rates of nausea, vomiting and diarrhea than other tetracyclines. Conclusion: Eravacycline is an effective new option for use in complicated intra-abdominal infections, and in particular, for the treatment of extended-spectrum ß-lactamase- and carbapenem-resistant Enterobacteriaceae-expressing organisms.

Optimizing therapy of bloodstream infection due to extended-spectrum ß-lactamase-producing Enterobacteriaceae.

PURPOSE OF REVIEW: Infections due to extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) are increasing worldwide. Carbapenems are usually regarded as the antibiotics of choice for the treatment of serious ESBL infections. However, because of the alarming emergence or carbapenem resistance, interest in effective alternatives has emerged. The present review summarizes the findings published on the antibiotics currently available for treatment of patients with an ESBL-E bloodstream infection (BSI). RECENT FINDINGS: Meropenem and imipenem are the drugs recommended for treatment of ESBL BSIs in critically ill patients, and in infections with high bacterial loads or elevated ß-lactam minimum inhibitory concentrations. Ertapenem should be reserved for patients with less severe presentations, and should be used at high doses. In milder presentations or BSIs from low-risk sources, other carbapenem-sparing alternatives could be considered: cephamycins, fluoroquinolones, and particularly a ß-lactam/ß-lactam inhibitor combination (particularly piperacillin/tazobactam). Optimized dosing of piperacillin/tazobactam is recommended (high doses and extended infusion). There are few data on the use of the promising newly available drugs (e.g. ceftolozane/tazobactam, ceftazidime/avibactam, cefiderocol, and plazomicin), and it seems reasonable to reserve them as last-resort drugs. SUMMARY: Carbapenems should be used in patients with serious infections; alternatives could be used individually, particularly for definitive treatment of patients with milder presentations.

Ceftazidime-Avibactam as Salvage Therapy for Infections Caused by Enterobacteriales Coresistant to Carbapenems and Polymyxins.

In this article, we report a case series of patients with infections caused by Enterobacteriales coresistant to carbapenems and polymyxins who were treated with ceftazidime/avibactam (CAZ-AVI) salvage therapy on a compassionate-use protocol. We enrolled 29 adult patients in 3 centers that had an infection due to a resistant microorganism and for whom the treatments available were considered ineffective, treated them with CAZ-AVI, and assessed clinical and microbiological cure at the end of treatment and all-cause mortality at 14 days and 30 days. The antimicrobial susceptibility profile was determined using broth microdilution, and total genomic DNA was sequenced. Twelve (41.4%) patients had bacteremia, and 48.3% (14/29) of the infections were treated with combination therapy. All strains were producers of KPC-2 and were susceptible to CAZ-AVI (MIC90, 1 µg/ml). Clinical success was high (24/29 [82.7%; 95% confidence interval, 64.2 to 94.2%]), even for the bacteremic cases (75%). The 14-day and 30-day mortality rates were 9/29 (31%) and 15/29 (51.7%), respectively. The 14-day mortality rate for pneumonia was the same as that for bloodstream infections (33.3%) and although not significant, we found that patients with renal impairment that received adjusted doses of CAZ-AVI had high mortality (4/9 [44%]; P = 0.22). We concluded that CAZ-AVI is an option for the treatment of severe infections due to difficult-to-treat drug-resistant Enterobacteriales.

Oral treatment options for patients with urinary tract infections caused by extended spectrum ßeta-lactamase (ESBL) producing Enterobacteriaceae.

INTRODUCTION: Frequent use of different antibiotics to treat urinary tract infections (UTIs) exerts a variety of selective pressure on pathogens which ultimately lead to the antimicrobial resistance. Extended Spectrum ßeta-Lactamase (ESBL) producing Enterobacteriacae causing UTIs, which are usually multidrug resistant organisms, pose a great therapeutic treatment challenge. Rediscovery of forgotten antibiotics such as pivmecillinam, fosfomycin, and nitrofurantoin may be helpful in this situation until the discovery of new agents. The main aim of present study was to determine the prevalence of ESBL producing Enterobacteriacae causing UTIs and their sensitivity profile to determine alternate effective oral treatment options. METHODS: This retrospective study was conducted to determine the prevalence of ESBL producing Enterobacteriacae from urine samples and their sensitivity profile (pivmecillinam, fosfomycin, nitrofurantoin, trimethoprim and ciprofloxacin) from September 2015 to September 2017. RESULTS: A total of 986 organisms were isolated from the urine samples of 680 patients. Approximately 77% isolates were obtained from female patients (526). Of 986 organisms, Escherichia coli was the most common isolated organism (889, 90%); followed by Klebsiella species (71, 7%) and other Enterobacteriacae (26, 3%). Of 889 E. coli, approximately 98%, 96%, and 93% were found to be sensitive to fosfomycin, pivmecillinam and nitrofurantoin respectively. On the other hand pivmecillinam was most effective against Klebsiella species (83%, 59); followed by fosfomycin (62%, 44) and nitrofurantoin (42%, 30). Of 26 other Enterobacteriacae, 23 (88%), and 22 (85%) were sensitive to pivmecillinam and fosfomycin while lower sensitivity rate (15%, 4) was noted against nitrofurantoin. More than 95% of all ESBL producing Enterobacteriacae were sensitive to pivmecillinam, fosfomycin and nitrofurantoin. Trimethoprim and ciprofloxacin were least effective. CONCLUSION: The emergence of multidrug resistant ESBL producing Enterobacteriacae restricts significantly the therapeutic options. This study shows higher sensitivity rates to pivmecillinam, fosfomycin and nitrofurantoin. We recommend their use to treat uncomplicated UTIs due to ESBL producing Enterobacteriacae.

Increasing the dosing of a Buttiauxella phytase improves phytate degradation, mineral, energy, and amino acid digestibility in weaned pigs fed a complex diet based on wheat, corn, soybean meal, barley, and rapeseed meal1.

This study evaluated the effects of increasing the dose of a 6-phytase from Buttiauxella on phytate degradation, mineral, energy, and AA digestibility in weaned pigs fed complex diets based on wheat, corn, soybean meal, barley, and rapeseed meal. A negative control (NC) diet containing no added inorganic phosphorus (P) and a reduction of 0.1% calcium (Ca) and 36 kcal/kg ME was supplemented with Buttiauxella phytase at 0, 250, 500, 1,000, or 2,000 FTU/kg diet and tested against a nutritionally adequate, positive control (PC) diet. One phytase units (FTU) is the amount of enzyme that liberates 1 micromole of inorganic phosphate per minute from a sodium phytate substrate at pH 5.5 and 37 °C. Barrows (Topigs × Pietrian; initial mean body weight 19.3 kg) were housed individually in metabolic crates and fed the test diets in mash form via 2 equal meals per day for 9 d (fed at 2.5 times the maintenance energy requirement), with 8 replicate pigs per treatment, in 2 experimental runs (total n = 48). After a 3-d adaptation period, urine and feces were collected over 5 d for measurements of apparent total tract digestibility (ATTD) and retention of nutrients. On day 9, pigs were euthanized and ileal digesta collected for measurements of apparent ileal digestibility (AID) of nutrients. Phytase improved (P < 0.05) digestibility of all measured AA except Trp (P < 0.1), and AID P, nitrogen, phytate, ATTD P, Ca versus NC. Increasing phytase dose from 0 (NC) to 2,000 FTU/kg increased AID Lys, Cys, Thr, Val, Ile, Leu, mean AA, P, N, phytate, ATTD P, N, Na, energy, ME, P retention (g/d), and reduced P excretion (g/d) in a linear or exponential manner (P < 0.05). Phytase at 2,000 FTU/kg improved AA digestibility by between +3.1 percentage points (Trp) and +8.8 percentage points (Cys) versus NC (average +6.3 percentage points) (P < 0.05). Phytase inclusion at 2,000 FTU/kg reduced P excretion (g/d) by 57% versus PC (P < 0.05). In conclusion, increasing Buttiauxella phytase in the range of 0 to 2,000 FTU/kg increased phytate degradation, improved AA and P digestibility, and reduced P excretion in weaned pigs fed complex diets.

Comparison of five methods for detection of carbapenemases in Enterobacterales with proposal of a new algorithm.

OBJECTIVES: The aim of this study was to evaluate the performance of five different carbapenemase tests and to develop an algorithm which will permit the detection of most common and rare carbapenemases in routine microbiology laboratories. METHODS: The immunochromatographic tests CARBA-5 (NG), RESIST-4 O.K.N.V. (Coris), the colorimetric ß-CARBA (BioRad), a newly developed carbapenem-inactivation method (CIM) supplemented with zinc (zCIM), and the Xpert Carba-R (Cepheid) were challenged with a collection of 189 molecularly characterized Enterobacterales isolates, including 146 carbapenemase producers (CPE): VIM (n = 48), OXA-48-like (n = 40), NDM (n = 29), KPC (n = 13), IMI (n = 9), IMP (n = 9), OXA-58 (n = 2), and GES (n = 2). RESULTS: The overall sensitivity/specificity values for the five carbapenemase detection tests were 84.2% (CI 77.6-89.2%)/100% (CI 91.8-100%) for RESIST-4, 88.2% (CI 82.1-92.4%)/100% (CI 91.8-100%) for CARBA-5, 88.2% (CI 82.1-92.4%)/100% (CI 91.8-100%) for Xpert Carba-R, 73.7% (CI 66.2-80.0%)/100% (CI 93.4-99.0%) for ß-CARBA, and 97.4% (CI 87.9-99.6%)/97.7% (CI 87.9-99.6%) for zCIM. The four common carbapenemases (KPC, OXA-48-like, NDM, and VIM) were detected with ≥97.6% sensitivity by all tests except for ß-CARBA (76.6% (CI 68.4-83.2%)). IMI and GES were only detected by zCIM (sensitivity 90.9% (CI 62.3-98.4%)). Based on these results a new algorithm was developed, consisting of an immunochromatographic assay as the first test followed by zCIM, which allows detection of 99.3% of all carbapenemases assessed. CONCLUSIONS: Except for ß-CARBA, all methods showed excellent sensitivity/specificity for the detection of the four most frequent carbapenemases. With the new algorithm, rare variants can also be detected. It is rapid, simple, and inexpensive and can be performed in any microbiology laboratory, as no PCR equipment is required.

Inappropriate empirical antibiotic therapy does not adversely affect the clinical outcomes of patients with acute pyelonephritis caused by extended-spectrum ß-lactamase-producing Enterobacteriales.

Extended-spectrum ß-lactamase-producing Enterobacteriales (ESBL-PE) are often associated with inappropriate empirical therapy (IAT). The aim of this study was to investigate whether IAT of acute pyelonephritis (APN) caused by ESBL-PE is related to adverse outcomes. A retrospective cohort study was performed at a tertiary-care hospital from 2014 through 2016. Patients who had APN caused by ESBL-PE and were definitely treated with appropriate antibiotics for at least 7 days were enrolled. IAT was defined as when inappropriate empirical antibiotics were given 48 h or longer after initial diagnosis of APN. Primary endpoint was treatment failure defined as clinical and/or microbiologic failure. Secondary endpoints were length of hospital stay and recurrence of APN. Propensity score matching was used to adjust heterogeneity of each group. Among 175 eligible cases, 59 patients received IAT and 116 patients received appropriate empirical antimicrobial therapy (AT). Treatment failure was observed in five (8.4%) patients and nine (7.8%) patients in each group, respectively. After matching, the treatment failure rate was similar between both groups (adjusted odd ratio [aOR] 1.05; 95% confidence index [CI] 0.26-4.15). The length of hospital stay (median 11 days in the IAT group versus 11 days in the AT group; P = 0.717) and absence of recurrence within 2 months (90.3% in IAT and 86.7% in AT; P = 0.642) were also similar. IAT did not adversely affect the clinical outcome. In this regard, clinicians should be more cautious about indiscriminate prescription of broad-spectrum antibiotics such as carbapenem empirically for treatment of APN possibly caused by ESBL-PE.

Rapid detection of OXA-48-like, KPC, NDM, and VIM carbapenemases in Enterobacterales by a new multiplex immunochromatographic test.

The rapid detection of carbapenemase-producing Gram-negative bacteria is indispensable to optimize treatment and avoid the further spread of these organisms. While phenotypic tests are time-consuming and PCR is expensive and not available in many routine laboratories, immunochromatographic tests (ICT) can provide rapid results at moderate cost. The aim of this study was to determine the performance of the new ICT RESIST-4 O.K.N.V. K-SeT (Coris BioConcept, Gembloux, Belgium) which can detect the four most prevalent carbapenemases: OXA-48-like, KPC, NDM, and VIM. Additionally, we analyzed the impact of different culture conditions on the sensitivity. The new ICT was challenged with 169 carbapenem-resistant isolates. Of these, 125 were carbapenemase producers: 43 OXA-48-like, 15 KPC, 29 NDM, and 43 VIM. The ICT correctly detected 129 of the 130 carbapenemases resulting in a sensitivity of 99.2% and specificity of 100% when tested from Mueller-Hinton agar (MHA). The sensitivity of the assay increased to 100% when performed from zinc-supplemented MHA and sheep blood agar (SBA) or when the inoculum was harvested from the inhibition zone of an ertapenem disk. All carbapenemase-negative carbapenem-resistant bacteria tested negative and no cross-reaction was observed. The new ICT is an excellent test for rapid diagnostic of carbapenemase-producing Gram-negatives in the routine laboratory. It is easy to handle and provides rapid results with a high sensitivity. For best results, we recommend to obtain the inoculum from a medium with sufficient zinc or from the inhibition zone of an ertapenem disk.

Rapid detection of carbapenemases directly from positive blood cultures by the ß-CARBA test.

The rapid detection of blood stream infections (BSI) by carbapenemase-producing Enterobacterales (CPE) is indispensable to early optimize antibiotic treatment and to improve survival. While phenotypic tests are time-consuming and PCR is expensive and not available in many routine laboratories, colorimetric tests (e.g., Carba NP test) can provide rapid results at moderate cost. However, up to now, the detection of CPE-BSI requires a further 3-h incubation in broth supplemented with zinc sulfate and imipenem after a blood culture has become positive, thereby causing delay and additional hands-on time. The purpose of this study was to develop and evaluate a new method for the detection of CPE directly from positive blood culture without the need for incubation in broth, based on the commercially available colorimetric ß-CARBA test. For the evaluation, blood cultures spiked with 140 different Enterobacterales isolates producing diverse beta-lactamases were tested with the new method. Of these, 70 were CPE (OXA-48-like, NDM, KPC, VIM, and GIM). After blood cultures turned positive, blood culture fluid was drawn, and erythrocytes were hemolyzed with SDS, washed, and equilibrated before the ß-CARBA was performed on the bacterial pellet. All carbapenemases were reliably detected, including weak carbapenemases of the OXA-48 group. The sensitivity was 100% (95% CI 94.9-100) and the specificity 94.3% (95% CI 89.2-99.4). The time to result was 20 to 45 min. Carbapenemases can rapidly and reliably be detected directly from blood cultures using the new method, which could help to improve the outcome of these difficult-to-treat infections.

Comparison of empirical therapy with cefoperazone/sulbactam or a carbapenem for bloodstream infections due to ESBL-producing Enterobacteriaceae.

Objectives: Carbapenems are widely recommended for the treatment of infections caused by ESBL producers however, non-carbapenem ß-lactams such as ß-lactam/ß-lactamase inhibitor combinations (BLBLIs) deserve consideration for the treatment of ESBL infections. Cefoperazone/sulbactam is one of the most commonly used BLBLIs in China; however, few outcome studies have been reported. In this study, we evaluated and compared the clinical efficacy of cefoperazone/sulbactam with that of a carbapenem in the treatment of bloodstream infections (BSIs) caused by ESBL-producing Enterobacteriaceae. Methods: Patients with monomicrobial ESBL-producing Enterobacteriaceae BSIs empirically treated with cefoperazone/sulbactam or a carbapenem were included. Outcomes of interest were clinical response and 14 day mortality. To make a comparison of the efficacy of cefoperazone/sulbactam and a carbapenem more accurate, propensity score analysis was performed. Results: No statistically significant differences in success rates or 14 day mortality were found between the cefoperazone/sulbactam (n = 17) and carbapenem (n = 46) groups. In the propensity score analysis with 17 case-control pairs, the success rate in the cefoperazone/sulbactam group (70.6%, 12/17) was lower than that in the carbapenem group (94.1%, 16/17), but the difference was not significant (P = 0.175). Sepsis-related mortality and 14 day mortality rates did not significantly differ either (P = 1.000 for both). In the cefoperazone/sulbactam group, 66.7% (2/3) of the patients with a Pitt bacteraemia score ≥5 died within 14 days, whereas none (0/14) of the patients with a Pitt bacteraemia score <5 died within 14 days (P = 0.022). Conclusions: This study showed that cefoperazone/sulbactam had a lower success rate and a higher 14 day mortality rate compared with carbapenems, although the differences were not statistically significant because of the small patient numbers. Further evaluation of cefoperazone/sulbactam is needed.

CNF1-like deamidase domains: common Lego bricks among cancer-promoting immunomodulatory bacterial virulence factors.

Alterations of the cellular proteome over time due to spontaneous or toxin-mediated enzymatic deamidation of glutamine (Gln) and asparagine (Asn) residues contribute to bacterial infection and might represent a source of aging-related diseases. Here, we put into perspective what is known about the mode of action of the CNF1 toxin from pathogenic Escherichia coli, a paradigm of bacterial deamidases that activate Rho GTPases, to illustrate the importance of determining whether exposure to these factors are risk factors in the etiology age-related diseases, such as cancer. In particular, through in silico analysis of the distribution of the CNF1-like deamidase active site Gly-Cys-(Xaa)n-His sequence motif in bacterial genomes, we unveil the wide distribution of the super-family of CNF-like toxins and CNF-like deamidase domains among members of the Enterobacteriacae and in association with a large variety of toxin delivery systems. We extent our discussion with recent findings concerning cellular systems that control activated Rac1 GTPase stability and provide protection against cancer. These findings point to the urgency for developing holistic approaches toward personalized medicine that include monitoring for asymptomatic carriage of pathogenic toxin-producing bacteria and that ultimately might lead to improved public health and increased lifespans.

A voltammetric test for the rapid discrimination of ß-lactamase-producing Enterobacteriaceae in blood cultures.

The accurate identification of ß-lactamases produced by Enterobacteriaceae is a major challenge in clinical laboratories in order to optimize antimicrobial treatment and patient care. We describe here a rapid voltammetric-based method to detect and to discriminate ß-lactamase activity in Enterobacteriaceae i.e., penicillinase, cephalosporinase (inducible or overproduced), extended-spectrum beta-lactamase and carbapenemase producers. After a 2-h growth step of the sample under three separate conditions: 1) LB (Luria-Bertani) medium, 2) LB supplemented with 4 µg/mL cefotaxime and 3) LB supplemented with 4 µg/mL cefotaxime and 100 µg/mL potassium clavulanate, the ß-lactamase activity was measured by incubating a 0.5 mM nitrocefin solution for 15 min followed by the voltammetric detection of the hydrolyzed nitrocefin with disposable carbon screen-printed sensors. The development and the calibration of the method were carried out by analyzing pure cultures of fifty-seven strains with well characterized ß-lactam-resistance phenotypes. Thanks to the combination of the three currents (i1, i2, i3) recorded for each tested bacteria, the proposed procedure allowed to distinguish the different classes of ß-lactamase producers. In the second part of the study, the method was applied to the analysis of one hundred and fifteen samples Enterobacteriaceae-positive blood culture samples of bacteraemic patients. Overall data showed that the voltammetric method offered a sensitivity of 100% and a specificity of 80%. Interestingly, all of sixteen samples infected by a third-generation cephalosporins-resistant bacteria (i.e. ESBL and overproduced cephalosporinase producers) were detected. This study clearly demonstrated that the voltammetric assay is an efficient alternative technique for the rapid discrimination of ß-lactamases-producing Enterobacteriaceae in blood culture. In contrast to the approved routine assays, the electrochemical test did not require isolated colonies to be performed and was thus carried out in less than 3 h which could allow early administration of an appropriate antibiotic therapy.

Colonization With Levofloxacin-resistant Extended-spectrum ß-Lactamase-producing Enterobacteriaceae and Risk of Bacteremia in Hematopoietic Stem Cell Transplant Recipients.

Background: Bacteremia caused by extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) is associated with inadequate empirical therapy and substantial mortality in neutropenic patients. Strategies are needed to identify neutropenic patients at high risk of these infections. Methods: From April 2014 to September 2016, we collected perianal swabs, both at admission and weekly thereafter, from patients undergoing hematopoietic stem cell transplantation (HSCT). Patients received prophylactic levofloxacin while neutropenic. Swabs were plated onto selective agar, colonies were identified and underwent antimicrobial susceptibility testing, and phenotypic ESBL testing and polymerase chain reaction for ß-lactamase genes were performed on ceftriaxone-resistant Enterobacteriaceae. We then determined the prevalence of pre-transplant ESBL-E colonization and risk of ESBL-E bacteremia. Colonizing and bloodstream isolates from patients with ESBL-E bacteremia underwent multilocus sequence typing and pulsed-field gel electrophoresis. Results: We analyzed 312 patients, including 212 allogeneic and 100 autologous HSCT recipients. Ten percent (31/312) of patients had pre-transplant ESBL-E colonization. Susceptibility rates of colonizing ESBL-E were: levofloxacin, 25%; cefepime, 9%; piperacillin-tazobactam, 84%; and meropenem, 97%. Of 31 patients colonized with ESBL-E pre-transplant, 10 (32%) developed ESBL-E bacteremia during their transplant admission, compared to 1 (0.4%) of 281 patients not colonized with ESBL-E (P < .001). All bloodstream ESBL-E were levofloxacin-resistant and colonizing and bloodstream isolates from individual patients had identical genotypic profiles. Conclusions: HSCT recipients who are colonized with levofloxacin-resistant ESBL-E pre-transplant and receive levofloxacin prophylaxis have high rates of bacteremia from their colonizing strain during neutropenia. Assessing for ESBL-E colonization in neutropenic patients could lead to optimization of empirical antibacterial therapy.

Activity of Ceftolozane-Tazobactam against Pseudomonas aeruginosa and Enterobacteriaceae Isolates Collected from Respiratory Tract Specimens of Hospitalized Patients in the United States during 2013 to 2015.

The activities of ceftolozane-tazobactam and comparator agents against organisms deemed to be the cause of pneumonia among patients hospitalized in the United States during 2013 to 2015 were evaluated. Organisms included 1,576 Pseudomonas aeruginosa and 2,362 Enterobacteriaceae isolates susceptibility tested using reference broth microdilution methods. Ceftolozane-tazobactam, cefepime, ceftazidime, meropenem, and piperacillin-tazobactam inhibited 96.3%, 84.8%, 83.5%, 80.0%, and 78.6%, respectively, of the P. aeruginosa isolates. Ceftolozane-tazobactam inhibited 77.5 to 85.1% of isolates nonsusceptible to antipseudomonal ß-lactams and 86.6% and 71.0% of the 372 (23.6% overall) multidrug- and 155 (9.8%) extensively drug-resistant isolates tested. The activity of this combination was greater than those of other ß-lactams evaluated against P. aeruginosa groups across all U.S. census divisions. Ceftolozane-tazobactam was active against 90.6% of the Enterobacteriaceae, being less active than only meropenem (95.6% susceptible) among the ß-lactams evaluated. Against 145 Escherichia coli and Klebsiella pneumoniae isolates carrying extended-spectrum-ß-lactamase (ESBL)-encoding genes without carbapenemases, ceftolozane-tazobactam inhibited 82.8% of these isolates and was more active than cefepime and piperacillin-tazobactam (15.2% and 74.3% susceptible, respectively). ESBL genes included in this analysis were mainly blaCTX-M-15-like (89 isolates) and blaCTX-M-14-like (22) genes but also blaSHV (31) and blaTEM (3). Ceftolozane-tazobactam also displayed activity (84.6% susceptible) against 13 isolates harboring acquired AmpC genes. All ß-lactams displayed limited activity against blaKPC-carrying isolates. Ceftolozane-tazobactam was the most active ß-lactam tested against P. aeruginosa isolates from isolates that were the probable cause of pneumonia and displayed in vitro activity against Enterobacteriaceae, including isolates resistant to cephalosporins and carrying ESBL genes.

"Double carbapenem" and oral fosfomycin for the treatment of complicated urinary tract infections caused by blaNDM -harboring Enterobacteriaceae in kidney transplantation.

Infections with carbapenemase-producing carbapenem-resistant Enterobacteriaceae represent an emergent problem worldwide. Treatment of infections caused by New Delhi metallo-beta-lactamase (NDM)-harboring Enterobacteriaceae is particularly challenging as it frequently involves the use of nephrotoxic agents, which is problematic in kidney transplant recipients and non-renal transplant patients with marginal kidney function. We present two cases of urinary tract infections caused by NDM-harboring Enterobacteriaceae successfully treated with a combination of "double carbapenem" and oral fosfomycin.

Interplay of classic Exp and specific Vfm quorum sensing systems on the phenotypic features of Dickeya solani strains exhibiting different virulence levels.

Bacteria from the genus Dickeya cause severe symptoms on numerous economically important plants. Dickeya solani is the Dickeya species most frequently found on infected potato plants in Europe. D. solani strains from different countries show high genetic homogeneity, but significant differences in their virulence level. Dickeya species possess two quorum sensing (QS) mechanisms: the Exp system based on classic N-acyl-homoserine lactone (AHL) signals and a specific system depending on the production and perception of a molecule of unknown structure, Virulence Factor Modulating (VFM). To study the interplay between these two QS systems, five D. solani strains exhibiting different virulence levels were selected. Mutants were constructed by inactivating genes coding for each QS system. Double mutants were obtained by simultaneous inactivation of genes coding for both QS systems. Most of the D. solani mutants showed an attenuation of chicory maceration and a decreased production of plant cell wall-degrading enzymes (PCWDEs) and motility, but to different degrees depending on the strain. The VFM-QS system seems to regulate virulence in both D. solani and Dickeya dadantii, but the AHL-QS system has greater effects in D. solani than in D. dadantii. The inactivation of both QS systems in D. solani did not reveal any additive effect on the tested features. The inactivation of vfm genes generally has a more dominant effect relative to that of exp genes. Thus, VFM- and AHL-QS systems do not work in synergy to modulate the production of diverse virulence factors and the ability to macerate plant tissue.

Drastic Genome Reduction in an Herbivore's Pectinolytic Symbiont.

Pectin, an integral component of the plant cell wall, is a recalcitrant substrate against enzymatic challenges by most animals. In characterizing the source of a leaf beetle's (Cassida rubiginosa) pectin-degrading phenotype, we demonstrate its dependency on an extracellular bacterium housed in specialized organs connected to the foregut. Despite possessing the smallest genome (0.27 Mb) of any organism not subsisting within a host cell, the symbiont nonetheless retained a functional pectinolytic metabolism targeting the polysaccharide's two most abundant classes: homogalacturonan and rhamnogalacturonan I. Comparative transcriptomics revealed pectinase expression to be enriched in the symbiotic organs, consistent with enzymatic buildup in these structures following immunostaining with pectinase-targeting antibodies. Symbiont elimination results in a drastically reduced host survivorship and a diminished capacity to degrade pectin. Collectively, our findings highlight symbiosis as a strategy for an herbivore to metabolize one of nature's most complex polysaccharides and a universal component of plant tissues.

Prevalencia en España de mecanismos de resistencia a quinolonas en enterobacterias productoras de betalactamasas de clase C adquiridas y/o carbapenemasas / Prevalence of quinolone resistance mechanisms in Enterobacteriaceae producing acquired AmpC Beta-lactamases and/or carbapenemases in Spain

Introducción: En los últimos años se ha observado un incremento de la resistencia a fluoroquinolonas en enterobacterias, estando asociado significativamente a la resistencia a betalactámicos. Nuestro objetivo fue conocer la prevalencia de mecanismos cromosómicos y plasmídicos de resistencia a quinolonas en aislados productores de betalactamasas de claseC adquiridas y/o carbapenemasas. Métodos: Se evaluó la presencia de mecanismos cromosómicos y plasmídicos de resistencia a quinolonas [mutaciones en la región determinante de resistencia a quinolonas de gyrA y parCy genes qnr, aac(6')-Ib-cr y qepA] en 289 aislados de enterobacterias productoras de betalactamasas de claseC adquiridas y/o carbapenemasas recogidos entre febrero y julio de 2009 en 35 hospitales españoles. Resultados: Se detectaron determinantes plasmídicos en 92 aislados (31,8%); en 83 aislados (28,7%) se detectó algún gen qnr, y en 20 (7%), la variante aac(6')-Ib-cr. El gen qnr más prevalente fue qnrB4 (20%), asociado en la mayoría de los casos a DHA-1. El 14,6% de los aislados con una CMI de ciprofloxacino superior a 0,25mg/l no presentaban mutaciones en gyrA ni parC, detectándose en el 90% de los mismos algún determinante plasmídico de resistencia a quinolonas. Conclusión: qnrB4 fue el determinante plasmídico más prevalente, claramente asociado a DHA-1. Los mecanismos plasmídicos en asociación con mecanismos cromosómicos diferentes a las mutaciones en los genes de las topoisomerasas (sobreexpresión de bombas de expulsión, alteración del lipopolisacárido o disminución de porinas) pueden dar lugar a valores de CMI de ciprofloxacino que superan los puntos de corte establecidos por los principales comités internacionales de definición de puntos de corte para interpretación de datos de sensibilidad (AU)

Background: Quinolone resistance in Enterobacteriaceae species has increased over the past few years, and is significantly associated to beta-lactam resistance. The aim of this study was to evaluate the prevalence of chromosomal- and plasmid-mediated quinolone resistance in acquired AmpC Beta-lactamase and/or carbapenemase-producing Enterobacteriaceae isolates. Methods: The presence of chromosomal- and plasmid-mediated quinolone resistance mechanisms [mutations in the quinolone resistance determining region (QRDR) of gyrA and parC and qnr, aac(6')-Ib-cr and qepA genes] was evaluated in 289 isolates of acquired AmpC Beta -lactamase- and/or carbapenemase-producing Enterobacteriaceae collected between February and July 2009 in 35 Spanish hospitals. Results: Plasmid mediated quinolone resistance (PMQR) genes were detected in 92 isolates (31.8%), qnr genes were detected in 83 isolates (28.7%), and the aac(6')-Ib-cr gene was detected in 20 isolates (7%). qnrB4 gene was the most prevalent qnr gene detected (20%), associated, in most cases, with DHA-1. Only 14.6% of isolates showed no mutations in gyrA or parC with a ciprofloxacin MIC of 0.5mg/L or higher, whereas PMQR genes were detected in 90% of such isolates. Conclusion: qnrB4 gene was the most prevalent PMQR gene detected, and was significantly associated with acquired AmpC Beta -lactamase DHA-1. PMQR determinants in association with other chromosomal-mediated quinolone resistance mechanisms, different to mutations in gyrA and parC (increased energy-dependent efflux, altered lipopolysaccharide or porin loss), could lead to ciprofloxacin MIC values that exceed breakpoints established by the main international committees to define clinical antimicrobial susceptibility breakpoints (AU)

Carbapenem-Resistant Enterobacteriaceae.

Carbapenem-resistant Enterobacteriaceae (CRE) have emerged as a major threat. Commonly used antibiotics are generally inactive against CRE. Therefore, timely detection of CRE is of paramount importance. Among CRE, those producing carbapenem-hydrolyzing ß-lactamase enzymes (carbapenemase-producing Enterobacteriaceae) are particularly of concern because they tend to spread, and treatment is difficult. The carbapenemase groups most commonly encountered include KPC, NDM, and OXA-48. Treatment options are limited and include combinations of polymyxins, tigecycline, aminoglycosides, or carbapenems; newer agents with activity against CRE and better safety profiles are becoming available and will likely emerge as the preferred therapy.