Frequent Carbapenemase Research Articles

Multicentre study of the main carbapenem resistance mechanisms in important members of the Enterobacteriaceae family in Iran

Resistance to carbapenems has been increasingly reported from the Enterobacteriaceae family, with different mechanisms in different geographic parts of the world. This study investigated the mechanisms of carbapenem resistance in Escherichia coli, Klebsiella pneumoniae and Enterobacter spp. carried out as a multicentre study (n = 10). All third-generation cephalosporin-resistant E. coli, K. pneumoniae and Enterobacter spp. that had been recovered from the selected provinces were included. Modified Hodge test and Carba NP test were done as a phenotypical method for detection of carbapenemase; the most common carbapenemase was detected by PCR. We evaluated the presence of an active efflux pump by using cyanide 3-chlorophenylhydrazone. Overexpression of AcrA/B and presence of OqxAB was detected by real-time PCR and conventional PCR respectively. Microorganisms in this study included 58 E. coli, 95 K. pneumoniae and 60 Enterobacter spp. Modified Hodge test showed a sensitivity of 41% and a specificity of 83%, and the Carba NP test showed a sensitivity of 26% and a specificity of 92% for detection of carbapenemase. OXA-48 was the most frequently detected carbapenemase, followed by NDM-1. Thirty-nine percent and 27% of positive cyanide 3-chlorophenylhydrazone test organisms included active AcrA/B and OqxAB efflux pumps respectively. The result showed the Carba NP test was more specific than MHT. Data confirmed the involvement of AcrA/B and OqxAB efflux pump as a carbapenem resistance mechanism in selected bacteria. Similar to other reports from the Middle East, we found OXA-48 and NDM-1 to be the most frequent carbapenemase.

841. Frequency of carbapenemase-encoding genes among Imipenem-Resistant Gram-negative Bacilli isolated from Latin America: Is there a Role for Imipenem/Relebactam? Results from SMART 2017-2018

BackgroundNew beta-lactamase inhibitors in combination with beta-lactams such as imipenem /relebactam (IMI/REL) were recently developed and approved for clinical use to overcome the emergence and spread of carbapenemase-producing Gram-negative bacilli (GNB). We evaluated the frequency of carbapenemase-encoding genes (CEG) among imipenem-resistant GNB isolated from Latin America through the SMART Program (2017-2018), in order to gain insight to the possible therapeutic role of IMI/REL in this region.Methods13,843 GNB isolates including Enterobacterales (ENT) and P. aeruginosa (PSA), were collected consecutively from 10 Latin American countries during 2017-2018. GNB were recovered from patients diagnosed with distinct body site infections including bloodstream and respiratory tract infections. MICs were determined and interpreted according to CLSI broth microdilution recommendations. IMI-resistant isolates were selected for characterization of carbapenemase content by PCR followed by DNA sequencing.ResultsIMI resistance rates for E. coli (EC; N= 4,877), K. pneumoniae (KPN; N=2,718), P. aeruginosa (PSA; 2,108), Acinetobacter spp. (N=711), and E. cloacae (ECL; N=578) were 1.0%, 17.9%, 31.7%, 71.3% and 6.4%, respectively. These species accounted for 79.4% of all collected isolates. Detection of CEG was carried out in nearly 62.5% of the IMI-resistant ENT and PSA isolates. blaKPC-2 was the most common CEG found in IMI-resistant KPN, followed by blaKPC-3, in most LATAM countries (Figure 1). MBL encoding genes were detected in 92/415 (22.2%) IMI-resistant PSA. blaVIM-2 was detected in 79.3% of these isolates, followed by IMP variants (20.6%). blaGES-5, -19, -20, and -26 were only detected in PSA isolated from Mexico, while blaSPM-1 was only observed in five Brazilian PSA. IMI/REL showed excellent activity against EC [MIC50/90, 0.12/0.5 µg/mL; 99.6% susceptible (S)], KPN (MIC50/90, 0.25/.05 µg/mL; 96.5%, %S), and ECL (MIC50/90, 0.25/0.5 µg/mL; 96.7%S).Most frequent carbapenemase encoding genes detected among IMI-resistant Enterobacterales (Panel A) and P. aeruginosa (Panel B) in Latin American countries Species distribution by infection site ConclusionImportant local variations were observed for some CEG variants detected only in specific countries. IMI/REL showed relevant in vitro activity against IMI-resistant ENT and MBL-negative PSA; and seems to be an important option for treatment of infections in LATAM.Disclosures Ana Cristina Gales, Medical Doctor, CRISTALIA (Consultant)EUROFARMA (Consultant)INFECTOPHARM (Consultant)MSD (Consultant, Grant/Research Support, Scientific Research Study Investigator)PFIZER (Consultant, Scientific Research Study Investigator)ZAMBON (Consultant) Elisa Beirao, Medical Doctor, MSD (Consultant, Grant/Research Support, Scientific Research Study Investigator)PFIZER (Consultant) Felipe Tuon, Medical Doctor, MSD (Consultant, Grant/Research Support, Scientific Research Study Investigator)PFIZER (Consultant)TEVA (Consultant) Thales Polis, Medical Doctor, MSD (Employee) Suellen Rodrigues, MPharm, MSD (Employee) Marina Della Negra, Medical Doctor, MSD (Employee) Tarik Andrade, Bsc Pharm, MSD (Employee) Fernando Serra, MD, MSD Brazil (Employee)

Phenotypic detection of Carbapenamase among Klebsiella pneumoniae isolated from clinical samples using modified Hodged test

Carbapenemases are microbial enzymes that confer resistance to virtually all available beta-lactam antibiotics and the most frequent carbapenemases are the Klebsiella pneumoniae Carbapenamase (KPC). Detection of carbapenemases is a significant infection control strategy as the enzymes are often associated with extensive antimicrobial resistance, therapeutic failures and mortality associated with infectious diseases. A total of 400 clinical samples were collected from different groups of patients in Abubakar Tafawa Balewa University Teaching Hospital, Bauchi, Nigeria and 118 K. pneumoniae were isolated using standard microbiological techniques. The isolates were subjected to antibiotic susceptibility testing by Kirby-Bauer disc diffusion method, then screened for Carbapenamase production using modified Hodge test. The results indicated that the isolates were resistant to Ampicillin (61.9%), Ceftriaxone (50.8%) and Ceftazidime (50.8%), then Ciprofloxacin (54.2%), but predominantly sensitive to Imipenem (66.9%), Eterpenem (60.2%) and Meropenem (65.3%). It was found that 38 (32.2%) of the isolates phenotypically shows the presence of Carbapenamase, with highest frequency of (40.7%) among patients, mainly adult females with cases of Urinary Tract Infections (UTIs) and the least from wound (11.8%).This study revealed that the isolates produced other beta-lactamases than KPC or variants of Carbapenamase that cannot be detected by modified Hodge test, thus shows low resistance to carbapenems. Therefore further studies is needed to genotypically confirm the presence of KPC in these isolates.

Prevalence of plasmid-encoded carbapenemases in multi-drug resistant Escherichia coli from patients with urinary tract infection in northern Iran.

Objective(s):Resistance to carbapenems as the last line for controlling resistant bacteria is increasing due to production of carbapenemase. The aim of this study was to detect the plasmid-encoded carbapenemases using phenotypic methods and multiplex PCR among the multi-drug resistant (MDR) isolates from patients with urinary tract infection (UTI) in northern Iran.Materials and Methods:Antimicrobial susceptibility testing and extended spectrum β-lactamase (ESBL) production test were performed for 91 MDR Escherichia coli strains by disc diffusion and double disk synergy tests (DDST), respectively. Carbapenemases production was confirmed using Hodge test, EDTA double disk synergy test (EDST) and combined disk test (CDT). The isolates were subjected to PCR targeting blaIMP, blaVIM, blaKPC and blaOXA-48 β-Lactamase genes. Results:Resistance of isolates to 1st, 2nd, 3rd, and 4th generations of cephalosporins, carbapenems, and penicillins were 73%, 84.5%, 62%, 37.5%, 17.5%, and 76%, respectively. Based on CDT and Hodge test, 1 (3%) and based on EDST, 2 (6%) of 33 ESBL producers synthesize a type of carbapenemase. The frequency of blaIMP, blaVIM, blaKPC, and blaOXA-48 genes was 8.7%, 9.8%, 2.1%, and 15.3%, respectively. Existence of blaIMP conferred more resistance to cephalotin, fosfomycin, and piperacillin (P≤0.01) and carrying blaVIM caused more resistance to cephalotin, cefepime, and ceftazidime (P≤0.01). The presence of blaKPC conferred more resistance to cephalotin and presence of blaOXA-48 caused more resistance to chloramphenicol and piperacillin (P≤0.05).Conclusion:Identification and controlling of this nearly low frequent ESBL and carbapenemase producing strains are important due to the presence of plasmid genes encoding carbapenemase.

Carbapenemase-producing Enterobacteriaceae circulating in the Reunion Island, a French territory in the Southwest Indian Ocean

BackgroundThe spread of carbapenemase-producing Enterobacteriaceae (CPE) in the Southwest Indian Ocean area (SIOA) is poorly documented. Reunion Island is a French overseas territory located close to Madagascar and connected with Southern Africa, Indian sub-continent and Europe, with several weekly flights. Here we report the results of the CPE surveillance program in Reunion Island over a six-year period.MethodsAll CPE were collected between January 2011 and December 2016. Demographics and clinical data of the carrier patients were collected. We determined their susceptibility to antimicrobials, identified the carbapenemases and ESBL by PCR and sequencing, and explored their genetic relationship using pulsed-field gel electrophoresis and multi-locus sequence typing.ResultsA total of 61 CPEs isolated from 53 patients were retrieved in 6 public or private laboratories of the island. We found that 69.8% of CPE patients were linked to a foreign country of SIOA and that almost half of CPE cases (47.2%) reached the island through a medical evacuation. The annual number of CPE cases strongly increased over the studied period (one case in 2011 vs. 21 cases in 2016). A proportion of 17.5% of CPE isolates were non-susceptible to colistin. blaNDM was the most frequent carbapenemase (79.4%), followed by blaIMI (11.1%), and blaIMP-10 (4.8%). Autochtonous CPE cases (30.2%) harboured CPE isolates belonging to a polyclonal population.ConclusionsBecause the hospital of Reunion Island is the only reference healthcare setting of the SIOA, we can reasonably estimate that its CPE epidemiology reflects that of this area. Mauritius was the main provider of foreign CPE cases (35.5%). We also showed that autochthonous isolates of CPEs are mostly polyclonal, thus unrelated to cross-transmission. This demonstrates the local spread of carbapenemase-encoding genes (i.e. blaNDM) in a polyclonal bacterial population and raises fears that Reunion Island could contribute to the influx of NDM-carbapenemase producers into the French mainland territory.

Infections due to carbapenemase-producing bacteria, clinical burden, and impact of screening strategies on outcome

ObjectivesTo characterize the risk factors, impact of screening, and clinical burden of colonization and/or infection by carbapenemase-producing bacteria (CPB) in hospitalized patients. MethodRetrospective study in a tertiary care hospital between 2008 and 2016. ResultsAmong 88 included patients, 41% were colonized, 59% developed an infection, and 69% of all cases were hospital-acquired. Risk factors for CPB contamination included recent invasive medical device (94% of patients), antibiotic therapy (82%), travel abroad (17%), and hospitalization (>50%) with 80% of all patients with underlying chronic condition. Intestinal carriage represented 89% of all colonization cases and 50% of infections were located in the urinary tract. The recent use of mechanical ventilation devices was significantly more observed in infected patients than colonized patients. The most frequent CPB was Klebsiella pneumoniae and the most frequent carbapenemase was OXA-48. Overall mortality rate was 19%. Prevalence of CPB detection in intensive care units (ICU) based on systematical rectal screen swab upon admission remained <0.5%. The infected/colonized ratio (CPB colonization cases evolving into an infection) was 23%. The time between CPB infection diagnosis and start of appropriate antimicrobial therapy increased from 1 day in previously screened patients with positive CPB to 4 days in patients with previous negative or absent screening. ConclusionOur results emphasize the importance of CPB screening in all ICU patients and in at-risk patients hospitalized in other units, to allow earlier adequate antibiotic therapy in case of infection which occurred in 23% of the colonized patients.

Pathogenicity of Clinical OXA-48 Isolates and Impact of the OXA-48 IncL Plasmid on Virulence and Bacterial Fitness.

OXA-48 is the most common carbapenemase in Enterobacterales in Germany and one of the most frequent carbapenemases worldwide. Several reports have associated blaOXA–48 with a virulent host phenotype. To challenge this hypothesis, 35 OXA-48-producing clinical isolates of Escherichia coli (n = 15) and Klebsiella pneumoniae (n = 20) were studied in vitro, in vivo employing the Galleria mellonella infection model and by whole-genome sequencing. Clinical isolates belonged to 7 different sequence types (STs) in E. coli and 12 different STs in K. pneumoniae. In 26/35 isolates blaOXA–48 was located on a 63 kb IncL plasmid. Horizontal gene transfer (HGT) to E. coli J53 was high in isolates with the 63 kb IncL plasmid (transconjugation frequency: ∼103/donor) but low in isolates with non-IncL plasmids (<10–6/donor). Several clinical isolates were both highly cytotoxic against human cells and virulent in vivo. However, 63 kb IncL transconjugants generated from these highly virulent isolates were not more cytotoxic or virulent when compared to the recipient strain. Additionally, no genes associated with virulence were detected by in silico analysis of OXA-48 plasmids. The 63 kb plasmid was highly stable and did not impair growth or fitness in E. coli J53. In conclusion, OXA-48 clinical isolates in Germany are diverse but typically harbor the same 63 kb IncL plasmid which has been reported worldwide. We demonstrate that this 63 kb IncL plasmid has a low fitness burden, high plasmid stability and can be transferred by highly efficient HGT which is likely the cause of the rapid dissemination of OXA-48 rather than the expansion of a single clone or gain of virulence.

Antimicrobial Susceptibility and Molecular Characterization of Carbapenemase-Producing Enterobacter spp. Community Isolates in Belgrade, Serbia.

Antimicrobial resistance represents the emerging problem of modern medicine. Despite the fact that Enterobacter spp. is one of the most resistant pathogens, there has been a paucity of data on molecular epidemiology and antimicrobial susceptibility of community isolates in European countries as well as in Serbia. This study was conducted in 2016 and 2017 with the aim to investigate the prevalence of carbapenem-resistant Enterobacter spp. community isolates, molecular determinants of carbapenem resistance, and their genetic relatedness. Seventeen (1.6%) of 1,040 isolates that were positive for carbapenemase screening in accordance with European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations were included in the study. Minimum inhibitory concentrations for selected antimicrobials were determined by broth microdilution and by disk diffusion for chloramphenicol. Multiplex polymerase chain reactions (PCRs) for blaKPC, blaNDM, blaIMP, blaVIM, and blaOXA-48-like carbapenemase genes were performed. Clonality was assessed by enterobacterial repetitive intergenic consensus (ERIC)-PCR analysis. All isolates were multidrug resistant. The most frequent carbapenemase gene found was blaNDM (70.6%), followed by isolates coharboring blaNDM and blaOXA-48-like genes (23.5%) and a single isolate with the blaOXA-48-like gene (5.9%). ERIC-PCR molecular typing showed six different clusters (A-F) with clonal relatedness among isolates from the same institution and association of clusters E and F with the blaNDM carbapenemase gene. Our results indicate the need for Enterobacter spp. surveillance both in the community and hospitals to prevent spreading of multiresistant clones.

Intestinal co-colonization with different carbapenemase-producing Enterobacterales isolates is not a rare event in an OXA-48 endemic area

BackgroundThe current spread of carbapenemase-producing Enterobacterales (CPE) is a great concern. MethodsWe recovered 198 CPE from 162 patients admitted in our Hospital (March 2014-March 2016) during the R-GNOSIS European Project. Microbiological features and plasmid characteristics of CPE recovered from patients co-colonized with multiple CPE were studied. FindingsThirty patients (18.5%; CI 95%= 12.5%–24.5%) presented co-colonization with multiple CPE producing the same (CPE-SC) (15.4%) or a different carbapenemase (CPE-DC) (4.3%). OXA-48 (83.3%) was the most frequent carbapenemase, followed by VIM-1 (26.7%), NDM-1 (10%) and KPC-3 (3.3%). CPE-DC-patients had longer admissions [63 days (20–107)] than the other patients. Moreover, hospital stay until CPE detection was lower [9 days (5–14)] (p = 0.0052) in CPE-SC-patients than in those with a single colonization; 56% showed co-colonization in the first positive sample, although most of them had previous admissions and had received multiple antibiotic treatments. CPE were more frequently recovered in clinical samples from co-colonized [CPE-DC (28.6%), CPE-SC (24%)] patients than from patients with a single CPE (15.2%). Among CPE-SCOXA-48 [80% (p = 0.11)], K. pneumoniae [88% (p = 0.006)] and E. coli [84% (p < 0.001)] were the most frequent species. In 60% of patients, K. pneumoniae and E. coli species were simultaneously recovered, frequently after a single OXA-48-K. pneumoniae colonization. High-risk clones (ST11, ST15, ST307) were detected in OXA-48-K. pneumoniae but a higher clonal diversity was found among E. coli. A frequent in-vivo cross-species plasmid transmission was shown, due to a dominant plasmid (IncL-pOXA-48), but also involving related or unrelated blaVIM-1-, blaNDM-1- and blaKPC-3-encoding plasmids. InterpretationCPE co-colonization status should be monitored during epidemiological surveillance cultures, as these patients might be at a higher risk for infection. FundingEuropean Commission Framework Programme 7 and Instituto de Salud Carlos III, Spain

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

ObjectivesThe 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. MethodsThe immunochromatographic tests CARBA-5 (NG), RESIST-4 O.K.N.V. (Coris), the colorimetric β-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). ResultsThe 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 β-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 β-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. ConclusionsExcept for β-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.

Screening for Carbapenemases in Ertapenem-Resistant Enterobacteriaceae Collected at a Tunisian Hospital Between 2014 and 2018.

BackgroundCarbapenem-resistance is frequently detected in Enterobacteriaceae isolated from patients in Tunisia. The study was performed to identify frequent carbapenemases in Tunisian isolates.MethodsBetween May 2014 and January 2018, 197 ertapenem-resistant Enterobacteriaceae were isolated at the microbiological department of the Military Hospital of Tunis. The strains were phenotypically characterized and then subjected to in-house polymerase chain reaction (PCR) targeting the carbapenemase genes blaIMP, blaVIM, blaNDM, blaSPM, blaAIM, blaDIM,blaGIM, blaSIM, blaKPC, blaBIC, and blaOXA-48.ResultsThe assessed 197 ertapenem-resistant Enterobacteriaceae from Tunis comprised 170 Klebsiella pneumoniae, 19 Enterobacter cloacae, 6 Escherichia coli, 1 Citrobacter sedlakii, and 1 Enterobacter asburiae. Thereby, 55 out of 197 isolates (27.9%) were from blood cultures, suggesting a systemic disease. The carbapenemase gene blaOXA-48 quantitatively dominated by far with 153 detections, followed by blaNDM with 14 detections, which were distributed about the whole study interval. In contrast, blaBIC and blaVIM were only infrequently identified in 5 and 3 cases, respectively, while the other carbapenamases were not observed.ConclusionsThe carbapenemase gene blaOXA-48 was identified in the vast majority of ertapenem-resistant Tunisian Enterobacteriaceae while all other assessed carbapenemases were much less abundant. In a quantitatively relevant minority of isolates, the applied PCR-based screening approach did not identify any carbapenemases.

Molecular characterization of multidrug resistant strains of Acinetobacter baumannii isolated from pediatric intensive care unit in a Chinese tertiary hospital

BackgroundAcinetobacter baumannii is a nosocomial pathogen which is reported as a major cause of morbidity and mortality in intensive care units (ICUs). However, there is a lack of analysis focused on multidrug-resistant Acinetobacter baumannii (MDRAB) infection among patients from pediatric intensive care unit (PICU) in China. The aim of this study was to investigate the molecular characterization of MDRAB isolated from PICU.MethodsIn this study, 86 isolates of MDRAB were collected from PICU patients, from the First Affiliated Hospital of Sun Yat-sen University. The minimal inhibitory concentrations (MICs) of the isolates against common antibiotics were determined. The carbapenemase-encoding resistance genes and AdeABC-AdeRS efflux system genes of these isolates were detected by PCR. Real-time PCR was performed to determine the relative expression of the relevant efflux pumps.ResultsAmong 86 strains of MDRAB, 76.7% (66/86) were carbapenem-resistant A. baumannii (CRAB). All 86 clinical isolates possessed the blaOXA-51 gene. BlaOXA-23 was detected as the second most frequent (90.7%) carbapenemase. Harboring AdeABC efflux pump genes was prevalent among the majority of the MDR isolates. Specially, the distributions of AdeABC-AdeRS efflux system genes in CRAB strains reached up to 90.0%. Compared with those of the CSAB strains, there was a statistically significant increasing distribution of the regulator AdeR and AdeS genes(p < 0.05). Moreover, CRAB strains showed significantly increased expression of AdeB(12.3- fold), but decreased expression of AdeR (3.3- fold)(p < 0.05).ConclusionThe present study showed a high distribution of multiple genes, mainly the genes of blaOXA-23/blaOXA-51 carbapenemase and AdeABC efflux pump, is responsible to distinct drug-resistance in PICU. It is urgent to strengthen the molecular epidemiological surveillance of pediatric MDRAB isolates to prevent further outbreaks. This study is of significant help for the clinicians to make therapeutic decisions and manage infection control in PICU.

Molecular Epidemiology and Drug Resistance Pattern of Carbapenem-Resistant Klebsiella pneumoniae Isolates from Iran.

The emergence and dissemination of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates and their involvement in several nosocomial outbreaks are of high concern. This study was conducted to investigate the genetic relatedness and molecular determinants of carbapenem resistance in 100 CRKP isolates. Susceptibility to carbapenems as well as other antibiotics was determined by using disk diffusion method. The Modified Hodge test was performed for detection of carbapenemase production. The minimum inhibitory concentrations of selected antibiotics were determined by broth microdilution method. The presence of blaOXA-48, blaKPC, blaNDM, and blaVIM carbapenemase genes was examined by PCR, and clonal relatedness of CRKP isolates was investigated by pulsed-field gel electrophoresis (PFGE) analysis. blaOXA-48 was the most frequent carbapenemase gene (72%), followed by blaNDM (31%). None of the isolates harbored blaKPC and blaVIM genes. PFGE separated the majority of isolates into 10 clusters, including the major clusters A and B, carrying blaOXA-48, and clusters C and D, carrying blaNDM, and 4 isolates had a unique PFGE pattern. An increased rate of colistin resistance (50%) was detected among the isolates. Tigecycline was found to be the most active agent against CRKP isolates. Our results revealed that high prevalence of blaOXA-48 and blaNDM carbapenamses and resistance to colistin are alarming threats, necessitating an immediate action to prevent the spread of carbapenem-colistin-resistant K. pneumoniae isolates in Iran.

Characterization of carbapenemase-producing Enterobacteriaceae from colonized patients in a university hospital in Madrid, Spain, during the R-GNOSIS project depicts increased clonal diversity over time with maintenance of high-risk clones

To describe the incidence and microbiological features of carbapenemase-producing Enterobacteriaceae (CPE) from colonized patients in a Spanish university hospital during a cluster-randomized study [the Resistance of Gram-Negative Organisms: Studying Intervention Strategies (R-GNOSIS) project] on isolation strategies for faecal ESBL carriers. From March 2014 to March 2016, 15556 rectal swabs from 8209 patients admitted in two surgical wards and two medical wards were collected and seeded on ESBL and CPE chromogenic agars. Carbapenemase characterization (PCR and sequencing) was performed, and antibiotic susceptibility (MIC), clonality (PFGE and MLST) and diversity (Simpson diversity index estimation) were determined. One hundred and ninety-eight CPE isolates, mainly Klebsiella pneumoniae (53.5%) and Escherichia coli (19.2%), were identified in 162 patients (2%). Prevalence of CPE carriage remained unchanged over time. Overall, amikacin (9.6%), tigecycline (9.6%) and colistin (0.5%) showed low non-susceptibility. The most frequent carbapenemase was OXA-48 (64.1%), followed by VIM-1 (26.8%), NDM-1 (5.3%) and KPC-3 (3.5%), and these were co-produced with ESBLs in 43.9%. OXA-48 plus CTX-M-15 was the most frequent association. Two major K. pneumoniae clones were identified (OXA-48-CTX-M-15-ST11 and VIM-1-SHV-12-ST54) with considerable genetic diversity among the remaining isolates, including OXA-48-E. coli. Species diversity tended to decrease from 0.75 in the first 6 months of the study to 0.43 in the final months. The emergence of new clones (i.e. OXA-48-Kluyvera spp. and NDM-1-K. pneumoniae ST437 and ST101) and displacement of other particular clones were also demonstrated. We describe a polyclonal and changeable CPE population over time. Coexistence of worldwide disseminated clones, such as ST11-OXA-48- K. pneumoniae, with unrelated and emerging OXA-48-E. coli clones, depicts a disturbing CPE epidemiology in our institution.

Molecular epidemiology of carbapenemase-producing Enterobacteriaceae infection/colonisation in a hospital in Madrid

IntroductionA description is presented on the molecular epidemiology of carbapenemase-producing enterobacteriaceae infection in a tertiary hospital. Material and methodsA study was made on all the carbapenemase-producing enterobacteriaceae isolations obtained between February 2015 and March 2016 in the Hospital Universitario 12 de Octubre (Madrid). Phenotypic and molecular methods were used. ResultsA total of 7 bacterial species were identified, with the majority being Klebsiella pneumoniae (K. pneumoniae) (78.9%) and Enterobacter cloacae (E. cloacae) (16.4%). The resistance of K. pneumoniae and E. cloacae for carbapenems was 88.7 and 88.6% for ertapenem, 21.4 and 54.3% for imipenem, and 20.8 and 34.3% for meropenem, respectively. The most frequent carbapenemase type was OXA-48 (91.1%) and VIM (71.4%) in E. cloacae. A total of 9 K. pneumoniae clonal types were identified, including a majority pertaining to the sequence type ST11. In E. cloacae, 16 clonal types were identified. ConclusionsThe current increase in carbapenemase-producing enterobacteriaceae is mainly due to the spread of OXA-48-producing K. pneumoniae.

The emergence of carbapenem-resistant Klebsiella pneumoniae isolates producing OXA-48 and NDM in the Southern (Asir) province, Saudi Arabia.

Objectives:To identify the prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) and the most common types of cabapenemases among CRKP in the Southern (Asir) province hospitals, Saudi Arabia.Methods:The cross-sectional study was conducted between late April and September in 2015. A total of 54 Klebsiella pneumoniae (K. pneumoniae) isolates with reduced sensitivity to carbapenems were obtained from various clinical specimens of the 2 largest hospitals in the Southern province. Minimum inhibitory concentrations (MICs) of carbapenems were confirmed using E-test. Molecular detection of the most common carbapenemase genes (blaIMP, bla-carbapenem-hydrolyzing oxacillinase [OXA-48], blaVIM, bla-New Delhi metallo-ß-lactamas [NDM], and blaKPC) was performed using multiplex-polymerase chain reaction.Results:The current study found that increasing age and intensive care unit admission were associated with CRKP isolation. The major type of carbapenemases was OXA-48 with 81.5% (n=44) and it seems to reach an endemic level. New Delhi metallo-ß-lactamas (NDM) was the second most frequent carbapenemase by 7.4% (n=4) of isolates while Verona integron-encoded metallo-ß-lactamase (VIM) was reported only in one isolate.Conclusion:Saudi Arabia receives large numbers of visitors and migrant workers from OXA-48 and NDM endemic countries such as Turkey, India, and Pakistan every year.

Molecular characterization of intestinal carriage of carbapenem-resistant Enterobacteriaceae among inpatients at two Iranian university hospitals: first report of co-production of bla NDM-7 and bla OXA-48.

Gastrointestinal colonization of carbapenem-resistant Enterobacteriaceae (CRE) could serve as a reservoir for the transmission of these pathogens in the clinical setting. The aim of this study was to investigate the intestinal carriage of CRE and to analyze risk factors for CRE carriage. Rectal swabs were collected from 95 patients at two Iranian university hospitals. CRE screening was performed using selective media (CHROMagar and MacConkey agar). Polymerase chain reaction (PCR) was used to detect carbapenemase-encoding genes. Clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE). The rate of carriage of CRE in hospitalized patients was 37.9%. Overall, 54 CRE isolates were identified, of which 47 were carbapenemase-producers. All of the 54 CRE were detected using CHROMagar compared with 52 CRE detected using MacConkey agar. Fifteen patients were colonized by multiple CRE isolates. Three significant risk factors for CRE carriage were detected: intensive care unit (ICU) hospitalization, antibiotic exposure, and mechanical ventilation. bla OXA-48 was the most frequent carbapenemase detected, followed by bla NDM-1 and bla NDM-7. Eleven carbapenemase-producing Enterobacteriaceae (CPE) isolates co-harbored bla NDM-1 and bla OXA-48. Also, six CPE isolates co-harbored bla NDM-7 and bla OXA-48. We did not detect bla KPC, bla GES, bla IMP, or bla VIM. PFGE analysis showed that Escherichia coli clones were diverse, while Klebsiella pneumoniae isolates were divided into four clusters. Cluster I was the major clone carrying bla OXA-48 and bla CTX-M-15 genes. In our study, the carriage rate of CRE was high and the emergence of CPE isolates among patients is alarming. The implementation of adequate preventive measures such as active surveillance is urgently needed to control the spread of CPE in the healthcare setting.

Risk factors for colonization by carbapenemase-producing enterobacteria at admission to a Surgical ICU: A retrospective study

IntroductionIn 2011, a hospital-wide outbreak of OXA-48 producing Klebsiella pneumoniae occurred in our hospital, an epidemiological setting of high ESBL-producing K. pneumoniae rates. This study identifies risk factors for colonization with carbapenemase-producing enterobacteria (CPE) at Surgical Intensive Care Unit (SICU) admission. MethodsA 2-year retrospective study was performed in all patients admitted to the SICU that following routine had a rectal swab collected upon admission. ResultsOf 254 patients admitted, 41 (16.1%) harbored CPE (five showing two carbapenemase-producing isolates). Most frequent carbapenemase-producing isolates and carbapenemases were K. pneumoniae (39/46, 84.8%) and OXA-48 (31/46; 76.1%), respectively. Carriers significantly had higher rates of chronic renal disease, previous digestive/biliary endoscopy, hospitalization, ICU/SICU admission, intraabdominal surgery, and antibiotic intake, as well as higher median values of clinical scores (SOFA, SAPS II and APACHE II). In the multivariate analysis (R2=0.309, p<0.001), CPE carriage was associated with prior administration of 3rd–4th generation cephalosporins (OR=27.96, 95%CI=6.88, 113.58, p<0.001), β-lactam/β-lactamase inhibitor (OR=11.71, 95%CI=4.51, 30.43, p<0.001), abdominal surgery (OR=6.33, 95%CI=2.12, 18.89, p=0.001), and prior digestive/biliary endoscopy (OR=3.88, 95%CI=1.56, 9.67, p=0.004). ConclusionsA strong association between production of ESBLs and carriage of CPE (mainly OXA-48 producing K. pneumoniae) was found. According to the model, the co-selection of β-lactamases by previous exposure to broad-spectrum cephalosporins and β-lactam/β-lactamase inhibitors (with lower relative risk), abdominal surgery and prior digestive/biliary endoscopy were factors associated with CPE carriage.

Effect of appropriate combination therapy on mortality of patients with bloodstream infections due to carbapenemase-producing Enterobacteriaceae (INCREMENT): a retrospective cohort study

The best available treatment against carbapenemase-producing Enterobacteriaceae (CPE) is unknown. The objective of this study was to investigate the effect of appropriate therapy and of appropriate combination therapy on mortality of patients with bloodstream infections (BSIs) due to CPE. In this retrospective cohort study, we included patients with clinically significant monomicrobial BSIs due to CPE from the INCREMENT cohort, recruited from 26 tertiary hospitals in ten countries. Exclusion criteria were missing key data, death sooner than 24 h after the index date, therapy with an active antibiotic for at least 2 days when blood cultures were taken, and subsequent episodes in the same patient. We compared 30 day all-cause mortality between patients receiving appropriate (including an active drug against the blood isolate and started in the first 5 days after infection) or inappropriate therapy, and for patients receiving appropriate therapy, between those receiving active monotherapy (only one active drug) or combination therapy (more than one). We used a propensity score for receiving combination therapy and a validated mortality score (INCREMENT-CPE mortality score) to control for confounders in Cox regression analyses. We stratified analyses of combination therapy according to INCREMENT-CPE mortality score (0-7 [low mortality score] vs 8-15 [high mortality score]). INCREMENT is registered with ClinicalTrials.gov, number NCT01764490. Between Jan 1, 2004, and Dec 31, 2013, 480 patients with BSIs due to CPE were enrolled in the INCREMENT cohort, of whom we included 437 (91%) in this study. 343 (78%) patients received appropriate therapy compared with 94 (22%) who received inappropriate therapy. The most frequent organism was Klebsiella pneumoniae (375 [86%] of 437; 291 [85%] of 343 patients receiving appropriate therapy vs 84 [89%] of 94 receiving inappropriate therapy) and the most frequent carbapenemase was K pneumoniae carbapenemase (329 [75%]; 253 [74%] vs 76 [81%]). Appropriate therapy was associated with lower mortality than was inappropriate therapy (132 [38·5%] of 343 patients died vs 57 [60·6%] of 94; absolute difference 22·1% [95% CI 11·0-33·3]; adjusted hazard ratio [HR] 0·45 [95% CI 0·33-0·62]; p<0·0001). Among those receiving appropriate therapy, 135 (39%) received combination therapy and 208 (61%) received monotherapy. Overall mortality was not different between those receiving combination therapy or monotherapy (47 [35%] of 135 vs 85 [41%] of 208; adjusted HR 1·63 [95% CI 0·67-3·91]; p=0·28). However, combination therapy was associated with lower mortality than was monotherapy in the high-mortality-score stratum (30 [48%] of 63 vs 64 [62%] of 103; adjusted HR 0·56 [0·34-0·91]; p=0·02), but not in the low-mortality-score stratum (17 [24%] of 72 vs 21 [20%] of 105; adjusted odds ratio 1·21 [0·56-2·56]; p=0·62). Appropriate therapy was associated with a protective effect on mortality among patients with BSIs due to CPE. Combination therapy was associated with improved survival only in patients with a high mortality score. Patients with BSIs due to CPE should receive active therapy as soon as they are diagnosed, and monotherapy should be considered for those in the low-mortality-score stratum. Spanish Network for Research in Infectious Diseases, European Development Regional Fund, Instituto de Salud Carlos III, and Innovative Medicines Initiative.

Epidemiología molecular de las infecciones/colonizaciones por enterobacterias productoras de carbapenemasas en un hospital de Madrid

IntroductionA description is presented on the molecular epidemiology of carbapenemase-producing enterobacteriaceae infection in a tertiary hospital. Material and methodsA study was made on all the carbapenemase-producing enterobacteriaceae isolations obtained between February 2015 and March 2016 in the Hospital Universitario 12 de Octubre (Madrid). Phenotypic and molecular methods were used. ResultsA total of 7 bacterial species were identified, with the majority being Klebsiella pneumoniae (K. pneumoniae) (78.9%) and Enterobacter cloacae (E. cloacae) (16.4%). The resistance of K. pneumoniae and E. cloacae for carbapenems was 88.7 and 88.6% for ertapenem, 21.4 and 54.3% for imipenem, and 20.8 and 34.3% for meropenem, respectively. The most frequent carbapenemase type was OXA-48 (91.1%) and VIM (71.4%) in E. cloacae. A total of 9K. pneumoniae clonal types were identified, including a majority pertaining to the sequence type ST11. In E. cloacae, 16 clonal types were identified. ConclusionsThe current increase in carbapenemase-producing enterobacteriaceae is mainly due to the spread of OXA-48-producing K. pneumoniae.