Factors associated with mortality in Infections caused by Carbapenem-resistant Enterobacteriaceae.

INTRODUCTION: There is little information about weigh of factors possibly associated with mortality, in infections caused by Carbapenem-resistant Enterobacteriaceae (CRE) in Latin America. METHODOLOGY: A case-controls study nested in a historical cohort was performed including all patients with CRE infections diagnosed between June 2013 and December 2018 at Hospital Universitario San Ignacio in Bogotá, Colombia. Univariate and multivariate analysis were performed to compare cases of mortality within the first month after the infection diagnosis with surviving patients. RESULTS: A total of 131 patients were included. The overall 30-day mortality rate was 38.17%. In the multivariate analysis, a direct association was found between mortality and septic shock (OR 26.7 CI6.6-107.3 p < 0.01), post-chemotherapy febrile neutropenia (OR 3.3 CI1.06-10.8 p = 0.04) and Charlson Index ≥ 3 (OR 5.5 CI 1.5-20.06 p < 0.01). An inverse association was found with interventions to control the infectious focus (OR 0.3 CI0.1-0.7 p < 0.01). The MIC of different antibiotics and the use of combined antibiotic therapy (triple therapy vs. double therapy or monotherapy) were not associated with mortality. CONCLUSIONS: In patients with CRE infections, septic shock, a Charlson comorbidity index ≥ 3, and post-chemotherapy febrile neutropenia are independently related to an increase in mortality. The control of the infectious focus is a protective factor. A rapid identification of these patients, and the implementation of measures to control infectious focus and to detect CRE colonization in patients who are going to be taken to myelosuppressive chemotherapy could impact positively the prognosis of these patients.

In vivo study assessed meropenem and amikacin combination therapy against carbapenem-resistant and carbapenemase-producing Enterobacteriaceae strains.

BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE), especially for carbapenemase-producing Enterobacteriaceae (CPE), is an emerging cause that pose a significant threat to public health. However, efficient therapy has not been established. We assessed the antimicrobial efficacy of meropenem (MEPM) and amikacin (AMK) combination therapy. MATERIAL AND METHODS: Total eight isolates of Escherichia coli or Klebsiella pneumoniae, including CRE and/or CPE have carbapenemase genes were used. The relationship between phenotype and in vivo efficacy was assessed in neutropenic murine thigh infection model. Efficacy was determined using the change in bacterial density and survival rate. RESULTS: The combination therapy showed enhanced antimicrobial activities against CRE+/CPE+ and CRE+/CPE-K. pneumoniae isolates than MEPM monotherapy (0.63 ± 0.04 vs. 2.56 ± 0.24 ⊿log10 cfu/mL, p < 0.05; -1.05 ± 0.15 vs. -0.48 ± 0.30 ⊿log10 cfu/mL, p < 0.05). Likewise, the combination therapy showed enhanced antimicrobial activities against CRE+/CPE+ and CRE+/CPE-E. coli isolates than MEPM monotherapy (0.90 ± 0.68 vs. 1.86 ± 0.23 ⊿log10 cfu/mL, p < 0.05; -1.81 ± 0.06 vs. -0.88 ± 0.23 ⊿log10 cfu/mL, p < 0.05). Also, combination therapy group showed similar to higher survival rates in CRE + E. coli infection mice, compared to MEPM monotherapy group. CONCLUSION: Our results are the first supportive data to threat CRE infections with combination therapy of MEPM and AMK with in vivo model. The current results verify the promising utility of the combination therapy with MEPM and AMK against CRE isolates with a wide range of MEPM MICs.

Synergistic in vitro activity between aztreonam and amoxicillin-clavulanate against Enterobacteriaceae-producing class B and/or class D carbapenemases with or without extended-spectrum ß-lactamases.

Introduction. Carbapenemase-producing Enterobacteriaceae have become a major public health concern over the last decade and treatment options are limited.Aims. We evaluated the synergistic activity of the combination of aztreonam (ATM) and clavulanate for 41 ß-lactam-resistant clinical isolates harbouring class B or/and class D carbapenemases combined or not with extended-spectrum ß-lactamases (ESBLs).Methodology. The MICs of ATM, with and without amoxicillin-clavulanate (AMC), were determined. Time-kill assays were performed for three representative strains.Results. The ATM-AMC combination had a synergistic effect on 34/41 (83 %) isolates. The MIC of ATM, in the presence of clavulanate, was ≤1 mg l-1 for 15/41 (37 %) isolates and ≤4 mg l-1 for 29/41 (71 %) isolates. Synergistic activity was observed for 34/37 (92 %) isolates producing ESBLs and carbapenemases, compared to 0/4 (0 %) for ESBL-negative strains. Complete or partial bactericidal activity was obtained when the MIC of the combination was 0.5 mg l-1 and 1.5 mg l-1 or 8 mg l-1, respectively.Conclusion. The combination of ATM and AMC could be an attractive unconventional treatment for infections due to carbapenemase- and ESBL-producing Enterobacteriaceae.

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.

Effectiveness of ceftazidime/avibactam as salvage therapy for treatment of infections due to OXA-48 carbapenemase-producing Enterobacteriaceae.

Background: Experience in real clinical practice with ceftazidime/avibactam is limited, and there are even fewer data on infections due to OXA-48-producing Enterobacteriaceae. Methods: We designed an observational study of a prospectively collected cohort of adult patients receiving ceftazidime/avibactam in our centre. Only the first treatment course of each patient was analysed. Efficacy and safety were evaluated as 14 and 30 day mortality, recurrence rate at 90 days, resistance development and occurrence of adverse effects. Results: Fifty-seven patients were treated with ceftazidime/avibactam. The median age was 64 years (range 26-86), 77% were male and the median Charlson index was 3. The most frequent sources of infection were intra-abdominal (28%), followed by respiratory (26%) and urinary (25%). Thirty-one (54%) patients had a severe infection (defined as presence of sepsis or septic shock). Most patients received ceftazidime/avibactam as monotherapy (81%) and the median duration of treatment was 13 days. Mortality at 14 days was 14%. In multivariate analysis, the only mortality risk factor was INCREMENT-CPE score >7 (HR 11.7, 95% CI 4.2-20.6). There was no association between mortality and monotherapy with ceftazidime/avibactam. The recurrence rate at 90 days was 10%. Ceftazidime/avibactam resistance was not detected in any case and only two patients developed adverse events related to treatment. Conclusions: Ceftazidime/avibactam shows promising results, even in monotherapy, for the treatment of patients with severe infections due to OXA-48-producing Enterobacteriaceae and limited therapeutic options. The emergence of resistance to ceftazidime/avibactam was not observed.

Multiplex Immunochromatographic Detection of OXA-48, KPC, and NDM Carbapenemases: Impact of Inoculum, Antibiotics, and Agar.

For the rapid detection of carbapenemase-producing Enterobacteriaceae (CPE), immunochromatographic lateral flow tests (ICT) have recently been developed. The aim of this study was to assess the new multiplex ICT Resist-3 O.K.N. and to investigate if it can be performed directly from susceptibility testing plates. Additionally, the impact of the inoculum and carbapenem disks on sensitivity and specificity was evaluated. The new ICT was challenged using 63 carbapenem-resistant Enterobacteriaceae (CRE) isolates, including 51 carbapenemase producers. It was assessed under five different conditions directly from Mueller-Hinton agar (MHA): 1 µl or 10 µl of inoculum harvested in the absence of antibiotic pressure or 1 µl taken from the inhibition zone of either an ertapenem, imipenem, or meropenem disk. The sensitivity of the ICT was 100% for OXA-48-like and KPC carbapenemases and 94.4% for the NDM carbapenemase with the 1-µl inoculum. When harvested adjacent to a carbapenem disk, the sensitivity increased to 100%. Additionally, with zinc-supplemented MHA, both the sensitivity increased and the NDM band became visible faster (mean time, 8 ± 3.9 min for MHA compared to 1.9 ± 1.5 min for MHA plus zinc; P = 0.0016). The specificity of the ICT was 100%. The Resist-3 O.K.N. ICT is a sensitive and rapid test for the detection of three highly prevalent carbapenemases. However, false-negative results for NDM can occur. We recommend an inoculum of 1 µl that is harvested adjacent to an ertapenem or meropenem disk and the use of agars with sufficient zinc content to achieve the best performance.

Prevalence and drug resistance characteristics of carbapenem-resistant Enterobacteriaceae in Hangzhou, China.

With the abuse of antimicrobial agents in developing countries, increasing number of carbapenem-resistant Enterobacteriaceae (CRE) attracted considerable public concern. A retrospective study was conducted based on 242 CRE strains from a tertiary hospital in Hangzhou, China to investigate prevalence and drug resistance characteristics of CRE in southeast China. Bacterial species were identified. Antimicrobial susceptibility was examined by broth microdilution method or epsilometer test. Resistant ß-lactamase genes were identified by polymerase chain reaction and sequencing. Genotypes were investigated by phylogenetic analysis. Klebsiella pneumoniae and Escherichia coli were the most prevalent types of species, with occurrence in 71.9% and 21.9% of the strains, respectively. All strains exhibited high resistance (> 70%) against ß-lactam antibiotics, ciprofloxacin, trimethoprim-sulfamethoxazole, and nitrofurantoin but exhibited low resistance against tigecycline (0.8%) and minocycline (8.3%). A total of 123 strains harbored more than two kinds of ß-lactamase genes. blaKPC-2, blaSHV-11, blaTEM-1, and blaCTX-M-14 were the predominant genotypes, with detection rates of 60.3%, 61.6%, 43.4%, and 16.5%, respectively, and were highly identical with reference sequences in different countries, indicating potential horizontal dissemination. IMP-4 was the most frequent class B metallo-lactamases in this study. In conclusion, continuous surveillance and effective prevention should be emphasized to reduce spread of CRE.

IMP-6 Carbapenemase-Producing Enterobacteriaceae Bacteremia Successfully Treated with Amikacin-Meropenem in Two Patients.

Infections caused by carbapenemase-producing Enterobacteriaceae (CPE) are becoming increasingly common worldwide. Although CPE infections can be fatal, few reports in the literature have described effective and successful treatments for infectious diseases caused by several types of IMP CPE, and, to our knowledge, no reports have described the successful treatment of IMP-6 CPE infections. We describe two patients who developed bacteremia caused by IMP-6 CPE after surgery for cancer who were successfully treated with amikacin plus high-dose prolonged-infusion meropenem. Both patients were treated over a 2-week period using amikacin 15 mg/kg at various intervals based on therapeutic drug monitoring and meropenem 2000 mg infused over 3 hours every 12 hours. The dosages of amikacin and meropenem were determined based on the creatinine clearance of each patient. Both patients were cured of their bacteremia and did not experience any antibiotic-related adverse effects. Based on the outcomes of these patients, it appears that amikacin plus high-dose prolonged-infusion meropenem may be safe and effective for the treatment of bacteremia caused by IMP-6 CPE.

ST37 Klebsiella pneumoniae: development of carbapenem resistance in vivo during antimicrobial therapy in neonates.

AIM: To investigate the mechanism leading to in vivo carbapenem resistance development in Klebsiella pneumoniae. METHODS: Carbapenemase was detected using the modified carbapenem inactivation method. ß-lactamases resistant genes were identified by PCR and sequencing. Clonal relatedness was evaluated by random amplified polymorphic DNA and multiple locus sequence typing. The relationship between sequence typing and resistant genes was analyzed by using the chi-squared test. RESULTS: All ST37 carbapenem-resistant isolates were blaOXA-1 positive and all ST37 carbapenem-sensitive isolates were blaOXA-1 negative at Stage I. A significant relationship between carbapenem resistance and blaOXA-1 was observed. The blaOXA-1 -positive rate was significantly higher in ST37 K. pneumoniae than others. CONCLUSION: This is the first study about the development of carbapenem resistance in vivo potentially mediated by blaOXA-1 in ST37 K. pneumoniae among neonates.