Bla IMP Research Articles

Prevalence and characterisation of carbapenemase encoding genes in multidrug-resistant Gram-negative bacilli.

Emerging worldwide in the past decade, there has been a significant increase in multidrug-resistant bacteria from serious nosocomial infections, especially carbapenemase-producing Gram-negative bacilli that have emerged worldwide. The objective of this study is to investigate carbapenem resistance in Gram-negative bacilli bacteria using phenotypic detection, antimicrobial resistance profiles and genotypic characterisation methods. 200 Gram-negative bacilli isolates were collected from different clinical specimens. All clinical samples were exposed to isolation and identification of significant pathogens applying bacteriological examination and an automated Vitek-2 system. The isolates were subjected to susceptibility tests by the Vitek-2 automated system and those isolates that were resistant to beta-lactam drugs, including carbapenems, third-generation cephalosporines or cefoxitin, were selected for phenotyping using Carba plus disc system assay for detection of carbapenemase-producing isolates. These isolates were further confirmed by molecular detection. PCR was used for the detection carbapenem-resistant genes (OXA-48, IMP, NDM, VIM, and KPC). 110 (55%) of 200 Gram-negative bacilli were identified as beta-lactam-resistant isolates. The frequency of carbapenem-resistant isolates was calculated to be 30.9% (n = 34/110). A collection totalling 65/110 (59%) isolates were identified as carbapenemase producers by phenotypic method. Moreover, among the 65 carbapenemase-producing Gram-negative isolates with a positive phenotype-based result, 30 (46%), 20 (30%) and 18 (27%) isolates were positive for OXA-48, KPC and MBL enzymes, respectively, as well as the production of 27% of AmpC with porin loss. Tigecycline was the most effective antibiotic that affected 70% of MDR isolates, but high rates of resistance were detected to other tested antimicrobials. Of interest, a high incidence of MDR, XDR and PDR profiles were observed among all carbapenemase-producing isolates. 36% (24/65) of the tested isolates were MDR to 3 to 5 antimicrobial classes. 29% (17/65) of the recovered isolates were XDR to 6 to 7 antimicrobial classes. Alarmingly, 24% (16/65) of isolates displayed PDR to all the tested 8 antimicrobial classes. Genotype assay, including 53 phenotypically confirmed carbapenemase-producing isolates of Gram-negative bacilli, found 51(96%) isolates were harbouring one or more genes. The most common carbapenemase gene was bla NDM 83% (44/53) followed by bla OXA-48 75% (40/53), bla VIM 49% (26/53) and bla IMP 43% (23/53), while the gene bla KPC was least frequent 7% (4/53). 92% (46/51) of isolates were involved in the production of more than one carbapenemase gene. This study demonstrated the emergence of carbapenemase-producing Gram-negative pathogens implicated in healthcare-related infections. Accurate identification of carbapenem-resistant bacterial pathogens is essential for patient treatment, as well as the development of appropriate contamination control measures to limit the rapid spread of pathogens. Tigecycline exhibited potent antimicrobial activity against MDR, XDR and PDR-producing strains that establish a threatening alert which indicates the complex therapy of infections caused by these pathogens.

Clinical and Microbiological Characterization of Carbapenem-Resistant Enterobacteriales: A Prospective Cohort Study.

Aim: We aim to depict the clinicoepidemiological and molecular information of carbapenem-resistant Enterobacteriales (CRE) in Chongqing, China. Methods: We performed a prospective, observational cohort study, recruiting inpatients diagnosed with CRE infections from June 1, 2018, to December 31, 2019. We carried out strain identification and molecular characterization of CRE. eBURST analysis was conducted to assess the relationships among the different isolates on the basis of their sequence types (STs) and associated epidemiological data using PHYLOViZ. Clinical parameters were compared between the carbapenemase-producing Enterobacteriales (CPE) and non-CPE group. Findings: 128 unique CRE isolates from 128 patients were collected during the study period: 69 (53.9%) CPE and 59 (46.1%) non-CPE. The majority of CPE isolates were bla KPC-2 (56.5%), followed by bla NDM (39.1%) and bla IMP (5.8%). Klebsiella pneumoniae carbapenemase (KPC)–producing clonal group 11 Klebsiella pneumoniae (K. pneumoniae) was the most common CPE. Antibiotic resistance was more frequent in the CPE group than in the non-CPE group. Independent predictors for CPE infection were ICU admission and hepatobiliary system diseases. Although, there was no significant difference in desirability of outcome ranking (DOOR) outcomes between the two groups. At 30 days after index culture, 35 (27.3% ) of these patients had died. Conclusion: CRE infections were related to high mortality and poor outcomes, regardless of CRE subgroups. CPE were associated with prolonged ICU stays and had different clinical and microbiological characteristics than non-CPE. The identification of CPE/non-CPE and CRE resistance mechanisms is essential for better guidance of the clinical administration of patients with CRE infections.

Performance of a loop-mediated isothermal amplification assay (Isoplex CRE-ART) to detect common carbapenemase-encoding genes in Gram-negative bacteria.

Carbapenem-resistant Gram-negative bacteria (CR-GNB) are a major source of nosocomial infections worldwide. In this study, the ability of a loop-mediated isothermal amplification (LAMP)-based method (Isoplex CRE-ART) to rapidly detect carbapenemase-encoding genes bla OXA-48-like, bla OXA-23-like, bla OXA-24-like, bla KPC, bla VIM, bla NDM and bla IMP in 231 carbapenem-resistant Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii isolates was investigated. The accuracy of the LAMP test was compared to results of molecular isolate characterization using a Laboratory Developed Test multiplex carbapenemase PCR assay. The LAMP test correctly identified the presence of on-panel carbapenemases with a sensitivity of 99.16 % [95 % confidence interval (CI): 95.39-99.96 %] and a specificity of 98.21 % (95 % CI: 93.72-99.68 %) in 60 min. Our findings suggest that the Isoplex CRE-ART assay is able to rapidly identify carbapenemase genes in CR-GNB and improves options for pathogen characterization in the context of clinical microbiological and infection control diagnostics.

Co-occurrence of Carbapenemase-encoding Genes Among Klebsiella pneumoniae Clinical Isolates: Positive Relationship of bla NDM and bla SIM with Imipenem Resistance

Background: Carbapenem-resistant Klebsiella pneumoniae (CR-KP), known as a significant public health threat, is the most common causative agent of nosocomial and community-acquired infections. Objectives: This study aimed to evaluate resistance to carbapenems and determine the prevalence of carbapenemase genes and multilocus sequence typing (MLST) of K. pneumoniae clinical isolates. Methods: One-hundred K. pneumoniae isolates were evaluated. The minimum inhibitory concentrations (MIC) of imipenem and meropenem were assessed by the broth microdilution method. Multiplex-polymerase chain reaction (PCR) was applied to detect 11 carbapenemase-encoding genes belonging to different classes. The alleles and sequence types (ST) of three isolates were identified by MLST. Results: The MIC of carbapenems for the isolates ranged from 0.062 to 32 µg/mL. Overall, resistance rates to imipenem and meropenem were reported 11% and 34%, respectively. The bla IMP gene was the most abundant (78.4%), followed by bla OXA-48 (48.6%), bla GIM (27%), bla KPC (27%), bla SIM (21.6%), bla BIC (21.6%), bla NDM (16.2%), bla AIM (16.2%), bla VIM (16.2%), bla DIM (8.1%), and bla SPM (8.1%). The co-existence of carbapenemase genes was observed in 81.8% of the isolates. A positive relationship was found between the presence of bla NDM and bla SIM and resistance to imipenem. Multilocus sequence typing results showed three different sequence types, including ST14, ST5188, and ST1861. Conclusions: This study revealed a high prevalence of CR-KP isolates that suggests a high risk of horizontal gene transfer and potential to spread resistance among other strains. Since STs are reported for the first time in Iran, they can be considered as emerging strains.

Clinical, phenotypic and genotypic profile of carbapenem resistant gram negative infections in intensive care units

Carbapenems are currently the only active beta-lactams effective against the ESBL producing pathogens; this has led to an increase in their use not only for documented infections but also for empirical treatment of acquired infections in ICU patients. Thus, there is a selective pressure for carbapenem resistance in intensive care units of tertiary care hospitals. Carbapenem resistant infections are associated with high morbidity & mortality. 1. To screen for carbapenem resistance among gram negative infections in ICU patients by disc diffusion & confirmation by Vitek 2 system; 2: To detect the carbapenemase production by phenotypic methods; 3: To confirm the presence of resistant gene by PCR; 4: To find out the attributable risk factors from the clinical history of such patients; 5: To follow up & estimate mortality rate in such infections and its statistical correlation A total of 160 gram negative isolates [E.coli(71), Klebsiella(63), Acinetobacter(10), Pseudomonas(9) and Enterobacter(7)] from patients of various intensive care units were screened by disc diffusion out of which 53(33.12%) were carbapenem resistant. Resistant isolates were further tested by Vitek 2 system for determination of MICs, Modified Hodge test(MHT) and Combined Disc test(CDT) for carbapenemase production and subjected to multiplex PCR for detection of resiatant gene i.e., bla NDM-1, bla VIM, bla IMP and bla KPC. Follow up of all the cases till the end of hospital stay was done and mortality rate was calculated.Results: 53 isolates(33.12%) were carbapenem resistant, 17 isolates were MHT positive while 39 were CDT positive. 24 isolates [E.coli(12), Klebsiella(7), Acinetobacter(3), Pseudomonas(1) and Enterobacter(1)] showed the presence of NDM-1 gene on PCR. Gentamicin(35%), Amikacin (45%), Tigecycline(88%) & Colistin(100%) were sensitive for carbapenem resistant GNBs. Mortality in carbapenem sensitive infections in ICUs was 21% whereas resistant infections showed 37% (p value <0.05).Conclusion: 45% of carbapenem resistance is due to presence of NDM-1 gene, E.coli was the commonest isolate. Other mechanisms of resistance such as excessive ESBL production, porin loss may be responsible for resistance in remaining isolates. Effective infection control measures should be taken to prevent the spread of these super bugs in a ICU.

English

Bacteria develop antimicrobial drug resistance through several mechanisms, the common one being the production of enzymes. As the number of antibiotics discovered is in notable numbers in the past few years, it is important to preserve high-end antibiotics for the treatment of multidrug-resistant organisms (MDROs) infections, by appropriate use of antibiotics. A study was conducted to record prevalence, phenotypic and genotypic characters of MDROs in our hospital, with reference to carbapenem resistance. 200 multidrug-resistant clinical isolates were collected in 6 months. Carbapenem-resistant organisms were detected phenotypically confirmed for the production of carbapenemases by modified Hodge test (MHT) and genotypic detection was done by a multiplex polymerase chain reaction (PCR) assay for the five most predominant carbapenemases (bla NDM-1, bla OXA-48 , bla VIM, bla IMP, bla KPC). The isolates consisted of E. coli (53 %) followed by K. pneumoniae (30 %), P. aeruginosa (13 %), and acinetobacter spp (4 %). Among these, 40 (20 %) isolates were carbapenem-resistant. Of these 40, 27 (67.5 %) showed an increase in zone size by the MHT, suggestive of metallo-beta-lactamase (MBL) mediated carbapenem resistance and about 32 (80 %) isolates were found to contain at least one carbapenemase gene. bla NDM-1 accounted for 37.5 % (12 / 32) of the isolates and was the most predominant one followed by bla OXA-48 [28 % (9 / 32)]. 22 % (7 / 32) of the isolates had one or more carbapenemase genes. Identifying the mechanisms of resistance of pathogens is important to implement strict infection prevention and control measures in the hospital to prevent the transmission of the resistant pathogens. KEY WORDS Multidrug-Resistant Bacteria, Bla NDM-1 Gene, Bla OXA-48 Gene, Carbapenem Resistance, Carbapenem Resistant Organisms.

Molecular Detection of bla(SHV), bla(IMP) and bla(VIM) ?-lactamases genes among Klebsiella pneumonia strains

Spreading of antibiotic resistance genes producing bacteria among patients usually caused potentialinfections for human with high morbidity and mortality especially Klebsiella pneumoniae and the fastdevelopment of Multi-drug resistant (MDR) strains has significantly increased and can be quite problematic.Thus, the current study was aimed to determine the prevalence of antibiotic resistance genes (?-lactamase)among K. pneumoniae isolates. Methods: Fifty K. pneumoniae isolates were collected from sputum samplesfor patients suffered respiratory infection. The detection of resistance genes (blaSHV, blaVIM, bla IMP)was performed by polymerase chain reaction (PCR). Results: The frequency of ?-lactamase-positive K.pneumoniae was 28%, and the prevalence of the blaSHV, blaVIM and blaIMP genes was 100%, 0% and 0%respectively. Conclusions: These results ?-lactamase genes believing multi-drug resistance genes. This helpto decrease treatment problems as a result of resistant bacterial infections and prevention of transmission ofdrug resistance by rapid discovery infection-control programs.

Phylogrouping, Serogrouping, Virulence Factors and Carbapenemase Genes among Carbapenemase-Producing Escherichia Coli From Urinary Tract Infections

Introduction: Escherichia coli is among major nosocomial pathogens causing urinary tract infections(UTIs). The emergence of carbapenem- resistant strains is a major concern regarding the UTI treatment. Thesubjective of this study included assessment of genetic relation and screening of virulence factors amongcarbapenemase producing E. coli from UTI.Materials and methods: Three-Hundred E. coli isolates were enrolled. Antibiotic susceptibility test wasconducted by disk diffusion as provided by clinical and laboratory standards institute (CLSI). Carbapenemaseproduction and presence of bla OXA-48, bla KPC, bla NDM, bla VIM and bla IMP genes were evaluated by PCRtechnique. Virulence factors genes were also screened by PCR technique. Genetic relation of isolates wasimplemented using phylogrouping and serogrouping.Results: Of 300 isolates, 11 (3.66%) of them were resistant to carbapenems (CR-E. coli). Imipenemminimum inhibitory concentration ranged 4-128µg/ml. The bla OXA-48 and blaIMP genes were co-existed inthree (1%) isolates (imipenem MIC: 64-128µg/ml), but the bla KPC, bla NDM and bla VIM were not amplified.Predominant virulence genes included iutA (n=293, 97.66%), fyuA (n=256, 85.33%), inh (n=249, 83%), traT(n=247, 82.33%), pap? (n=96, 32%), fimH (n=93, 31%), csgA (n=92, 30.66%). All the CR-E. coli containedthe iutA, fyuA, traT, papII, fimH and csgA genes. O1 (32%), O16 (15%) and O25 (7%) serogroups werepredominant and 6/11, 4/11 and 1/11 of CR-E. coli belonged to O1, O25 and O75 serogroups, respectively.Among eleven CR-E. coli isolates, nine of them were belonged to the B2 phylogroup and two isolates werebelonged to B1 phylogroup.Conclusion: CR-E. coli contained the blaIMP and blaOXA-48 genes and predominantly O1 serogroup. Highrate of virulence factors among CR-E. coli from UTI is a concern in Baghdad hospitals. The spread ofisolates with resistance to last-line antibiotics must be controlled.

The extent of carbapenemase-encoding genes in public genome sequences.

Genome sequences provide information on the genetic elements present in an organism, and currently there are databases containing hundreds of thousands of bacterial genome sequences. These repositories allow for mining patterns concerning antibiotic resistance gene occurrence in both pathogenic and non-pathogenic bacteria in e.g. natural or animal environments, and link these to relevant metadata such as bacterial host species, country and year of isolation, and co-occurrence with other resistance genes. In addition, the advances in the prediction of mobile genetic elements, and discerning chromosomal from plasmid DNA, broadens our view on the mechanism mediating dissemination. In this study we utilize the vast amount of data in the public database PATRIC to investigate the dissemination of carbapenemase-encoding genes (CEGs), the emergence and spread of which is considered a grave public health concern. Based on publicly available genome sequences from PATRIC and manually curated CEG sequences from the beta lactam database, we found 7,964 bacterial genomes, belonging to at least 70 distinct species, that carry in total 9,892 CEGs, amongst which blaNDM, blaOXA, blaVIM, blaIMP and blaKPC. We were able to distinguish between chromosomally located resistance genes (4,137; 42%) and plasmid-located resistance genes (5,753; 58%). We found that a large proportion of the identified CEGs were identical, i.e. displayed 100% nucleotide similarity in multiple bacterial species (8,361 out of 9,892 genes; 85%). For example, the New Delhi metallo-beta-lactamase NDM-1 was found in 42 distinct bacterial species, and present in seven different environments. Our data show the extent of carbapenem-resistance far beyond the canonical species Acetinobacter baumannii, Klebsiella pneumoniae or Pseudomonas aeruginosa. These types of data complement previous systematic reviews, in which carbapenem-resistant Enterobacteriaceae were found in wildlife, livestock and companion animals. Considering the widespread distribution of CEGs, we see a need for comprehensive surveillance and transmission studies covering more host species and environments, akin to previous extensive surveys that focused on extended spectrum beta-lactamases. This may help to fully appreciate the spread of CEGs and improve the understanding of mechanisms underlying transmission, which could lead to interventions minimizing transmission to humans.

Molecular search of some antibiotic-borne genes of the clinical Pseudomonas aeruginosa plasmid

Clinical samples which included wounds, burns, ear infections, urinary tract infections (UTI), and skin from 300 patient from a different hospital in Thi-Qar province, and 100 skin and stool samples from (healthy people) as control, for investigating the presence of pseudomonas spp. Where carried out through October 2019 till January 2020. The samples were identified based on the morphological , microscopical characteristics of the colonies and biochemical tests, then confirmed by API-20 NE, VITEK2- compact system and the molecular detection based on the 16SrRNA gene, final diagnosis showed that 60 isolates belong to target bacteria were distributed as 30(50%) of burns, 5(8.3) isolates of wounds, 7(11.6) isolates of ear infection, 4(6.6) isolates (sputum),4(6.6)isolates of urinarytract infection, and (8 (13.3),2(3.3)) isolates stool samples and skin swabs respectively, as control samples). All isolates were tested for susceptibility test toward 13 antibiotics using the disc diffusion method, the results showed a high resistance among isolates against Tetracycline, Gentamycin, Amikacine. moderate resistance against Cefepime, Ceftazidime, and Imipenem. And low resistance towards Meropenem, and Ciprofloxacin. The results of antibiotic-resistance genes was diagnostic by Polymerase chain reaction (PCR) amplify based on specific sequences for (MBLs genes)bla VIM ,bla IMP, and bla NDM genes, showed that 26 (43.3%) of isolates have bla VIM gene, 16 (26.6%) of isolates have bla IMP gene, and 11 (18.3%)of isolates have bla NDM gene. while the results of (AME-genes) indicated that 30 (50%) of isolate have aac (6)-I gene and 8(13.3%) of isolate have aph (3)-VI gene. A comparison is made between the presence of genes on the plasmid or the chromosome,the results was increased the antibiotic- resistance genes on the plasmid. DNA partial sequencing was done for four isolates revealed some variants in different samples while some isolates showed 100% similarity with the referencing genome.

Phenotypic methods for detection of metallobetalactamase in Meropenem resistant Pseudomonas aeruginosa and molecular detection of blaIMP & blaVIM genes carrying strains

Introduction and Objectives: Pseudomonas aeruginosa is one of the major organisms responsible for nosocomial infections such as pneumonia, UTIs, surgical site infections, and bloodstream infections.1 High intrinsic and acquired resistance to many antimicrobial agents have allowed P. aeruginosa to persist in both community and hospital settings. This study was done to find the prevalence rate of Meropenem resistant Pseudomonas aeruginosa carrying metallobeta lactamase producing genes. Materials and Methods: The study included a total of 100 non-duplicate clinically significant, random bacterial isolates obtained from a North Indian rural tertiary care hospital (Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, India) from various clinical specimens, over a period of one year (January2012 to December 2012) . Identification of organisms was done using the standard microbiological techniques as described by Colle et al 1996.7 The antimicrobial susceptibility testing was performed by Kirby Bauer disc diffusion method. To detect MBL producing isolates phenotypicaly, Disc potentiation test (DPT) and Double disc synergy test (DDST) were performed. PCR was performed on Meropenem resistant isolates to detect blaIMP and blaVIM genes. Results: Out of 100 examined isolates, 36% isolates were resistant to Meropenem. Out of these Meropenem resistant strains, 44.4%(16) P. aeruginosa isolates were MBL producers as detected by DDST method and 69.44%(25) isolates were MBL producers phenotypically by DPT method . PCR revealed prescence of bla VIM gene in 16.66%(6) of Meropenem resistant Pseudomonas aeruginosa isolates and 38.88% (14) isolates were found to be carrying bla IMP gene . Three isolate were shown to carry both blaIMP and blaVIM genes. Conclusion: Resistance of P. aeruginosa isolates to Meropenem due to MBL enzymes is increasing in rural area. Resistance due to MBL has clinical significance, rapid detection of MBL producing strains followed by

Characterization of the Plasmidome Encoding Carbapenemase and Mechanisms for Dissemination of Carbapenem-Resistant Enterobacteriaceae.

Carbapenem-resistant Enterobacteriaceae (CRE) infections, high in morbidity and mortality, pose serious clinical challenges due to limited treatment options. A previous CRE surveillance study on 1,507 patients from 43 hospitals in Osaka, Japan, revealed that 12% of patients carried CRE and that 95% of the CRE isolates were IMP-type carbapenemase producers. Here, the mechanisms for this regional dissemination of a single carbapenemase gene were investigated. Since the dissemination of CRE is primarily due to the transmission of carbapenemase genes located on plasmids, we analyzed the plasmidome of 230 CRE isolates carrying bla IMP by whole-genome sequencing and Southern blotting. bla IMP-6 was found to be predominantly disseminated among chromosomally distinct isolates through the pKPI-6 plasmid. Underlying the vast clonal dissemination of pKPI-6, various subpopulations deriving from pKPI-6 were identified, which had acquired advantages for the dissemination of CRE isolates. A cluster exhibiting heteroresistance against meropenem by the transcriptional regulation of bla IMP-6 caused an outbreak likely through covert transmission of bla IMP-6 For stable carriage of bla IMP-6, they occasionally integrated bla IMP-6 on their chromosomes. In addition, we detected one isolate that broadened the range of antimicrobial resistance through a single point mutation in bla IMP-6 on pKPI-6. Multifaceted analysis of the plasmidome granted us more accurate perspectives on the horizontal spread of CRE isolates, which is difficult to trace only by comparing the whole genomes. This study revealed the predominant spread of a specific carbapenemase-encoding plasmid accompanying the emergence of phenotypically diverse derivatives, which may facilitate further dissemination of CRE in various environments.IMPORTANCE Global dissemination of carbapenem-resistant Enterobacteriaceae (CRE) threatens human health by limiting the efficacy of antibiotics even against common bacterial infections. Carbapenem resistance, mainly due to carbapenemase, is generally encoded on plasmids and is spread across bacterial species by conjugation. Most CRE epidemiological studies have analyzed whole genomes or only contigs of CRE isolates. Here, plasmidome analysis on 230 CRE isolates carrying bla IMP was performed to shed light into the dissemination of a single carbapenemase gene in Osaka, Japan. The predominant dissemination of bla IMP-6 by the pKPI-6 plasmid among genetically distinct isolates was revealed, as well as the emergences of pKPI-6 derivatives that acquired advantages for further disseminations. Underlying vast clonal dissemination of a carbapenemase-encoding plasmid, heteroresistance was found in CRE offspring, which was generated by the transcriptional regulation of bla IMP-6, stabilization of bla IMP-6 through chromosomal integration, or broadened antimicrobial resistance due to a single point mutation in bla IMP-6.

Panorama of carbapenemases in PeruUm panorama das carbapenemases presentes no Peru

RESUMENObjetivo.Describir los genotipos de las carbapenemasas reportadas de aislamientos microbiológicos de pacientes en Perú.Métodos.Se realizó una búsqueda sistemática de la literatura biomédica publicada desde el 1 enero de 2000 hasta el 15 de setiembre de 2019 en las bases de datos PubMed, SCOPUS, Biblioteca Virtual de Salud, Biblioteca Virtual de CONCYTEC, Google Scholar y otras fuentes de publicaciones de resúmenes o póster en congresos nacionales o internacionales sobre carbapenemasas con confirmación genotípica; la selección y extracción de datos fue por pares.Resultados.Se incluyeron 14 estudios en los que se realizó la caracterización genotípica de 313 carbapenemasas. Ciento tres de estos reportes pertenecían a estudios efectuados en enterobacterias; de estos, 74 fueron en Klebsiella pneumoniae, 11 en Proteus mirabilis, 7 en Enterobacter cloacae y 11 en otras. Sesenta y una de estas 103 corresponden a blaNDM, 39 a blaKPC y 3 a blaIMP. Según su estructura molecular, 64 son metalobetalactamasas y 39 son serinbetalactamasas. En Pseudomonas aeruginosa se incluyeron 84 reportes, 79 corresponden a blaIMP, 4 a blaVIM, y 1 a blaGES. En Acinetobacter baumannii 126 reportes, 55 corresponden a blaOXA-23, 66 a blaOXA24, 3 a blaNDM y 2 a blaOXA-143.Conclusiones.Existe un número escaso de publicaciones respecto a carbapenemasas de pacientes en Perú; los reportes genotípicos provienen en su mayoría de hospitales de la capital del país. Esta es la primera revisión que intenta conocer los tipos de carbapenemasas reportadas en enterobacterias, P. aeruginosa y A. baumannii.

Frequency of Metalo beta Lactamase genes, bla IMP1, INT 1 in Acinetobacter baumanii isolated from burn patients North of Iran

ObjectiveAcinetobacter baumanii is one of the most important pathogenic bacteria causing infectious diseases. The aim of this study was to evaluate the antibiotic resistance and determine the frequency of β-lactamase and class I integron genes in clinical strains of Acinetobacter baumanii isolated from burn patients in Sari, North of Iran. MethodA. baumanii specimens were collected from 2016 to 2019. After culture in a standard medium, the presence of A. baumanii was confirmed by biochemical tests. Antibacterial sensitivity test against ciprofloxacin, imipenem, meropenem, Cefepime, ceftazidime, gentamicin, amikacin and colistin was performed using disc diffusion method on the Muller-Hinton agar medium. Finally, polymerase chain reaction was performed to determine the resistance genes. ResultsA total of 150 A. baumanii were isolated. The results of the pattern of resistance of A. baumanii to the antibiotics tested were as follows: ceftazidime (100%), cefepime (94%), meropenem (91%), imipenem (88%), ciprofloxacin (80%), amikacin (78%), gentamicin (63%), colistin (10%). The study showed that 31% of the isolates produced the metallo-β-lactamases (MBLs) enzyme. Finally, by PCR method, blaIMP, blaVIM and class I integron were identified in, 45%, 35% and 60% of these isolates, respectively. ConclusionThis study revealed an increased frequency of MBL-encoding genes (VIM, IMP) and class I integron in A. baumannii isolates. Also, the results of this study showed that the rate of resistant to antibiotic among A. baumanii is high. In the present study, the only antibiotic that was suitable for the treatment of these patients was colistin. These results suggest further studies on the logical use of the drug in the treatment of A. baumanii.

Phenotypic synergy testing of ceftazidime–avibactam with aztreonam in a university hospital having high number of metallobetalactamase producing bacteria

Background Ceftazidime–avibactam combination with aztreonam and role of rapid synergy reporting has not been widely evaluated. Also the synergy correlation with various betalactamases has not been widely studied. Methods We studied phenotypic synergy testings and molecular detection of betalactamases in our university hospital where we have large number of mellatobetalactmase producing bacteria. We tested two phenotypic synergy methods for ceftazidime-avibactam with aztreonam (Disc-E strip method, E strip-Agar method) for rapid reporting to clinicians (153 isolates). The treatment (colistin, ceftazidime-avibactam, ceftazidime-avibactam with aztreonam) was guided as indicated in the synergy testings. The resistance genes in bacteria were identified by polymerase chain reaction (PCR) and correlated with synergy results. Results The highest synergy was seen in Klebsiella pneumoniae by Disc-E strip and E strip-Agar method (86% and 84% respectively). About 70% of Pseudomonas aeruginosa and 29% of Escherichia coli showed synergy. Molecular methods revealed multiple resistance gene combinations and bla NDM (96%) was predominant gene in isolates showing synergy. Among isolates that were sensitive to ceftazidime–avibactam, the predominant genes were bla OXA-48 and bla IMP. Rapid laboratory reporting led to proper utilization of antibiotic combinations. Conclusions Ceftazidime–avibactam and aztreonam rapid synergy testing will be highly beneficial in treatment of infections by metallobetalactamase producing resistant bacteria, especially K. pneumoniae and P. aeruginosa.

Genotyping and molecular characterization of clinical Acinetobacter baumannii isolates from a single hospital in Southwestern Iran

ABSTRACT Acinetobacter baumannii (A. baumannii) is a pathogen responsible for nosocomial infections among the hospitalized patients. The aim of this study was to investigate genotyping and molecular characterization and to examine the biofilm formation ability of A. baumannii isolates. In total, 70 A. baumannii isolates were collected from patients admitted to Imam Khomeini Hospital in Ahvaz, Southwestern Iran. Minimum inhibitory concentrations (MIC) test was performed using Vitek 2 system. The presence of genes encoding metallo-β-lactamases, oxacillinases, and integrase and the biofilm formation ability were then evaluated. Multiple locus variable-number tandem repeat (VNTR) analysis (MLVA) typing and multiplex PCR were performed to determine the genetic relationships. The blaOXA-23-like gene had the highest prevalence. The frequency of genes encoding bla SPM, bla IMP, and bla VIM among MDR A. baumannii isolates were 12 (17.1%), 18 (25.7%), and 22 (31.4%), respectively. Moreover, 46 isolates (75.4%) harbored class I integron and 10 isolates (16.39%) carried class II integron. The number of weak, moderate and strong biofilm-producing isolates were 3 (4.3%), 7 (10%), and 55 (78.5%), respectively. The results showed that 70 A. baumannii isolates were grouped into 12 distinct MLVA types with five clusters and four singleton genotypes. In addition, 25 (35.7%) isolates were assigned to international clone (IC) variants, 37 (52.8%) isolates belonged to group 1 (IC II), and 8 (11.4%) isolates belonged to group 2 (IC I). Our findings revealed that the population structure of the A. baumannii isolates was genetically diverse. More focus on genetic variation and antibiotic resistance of A. baumannii isolates are recommended.

Multidrug-resistant Escherichia coli isolated from a dog with a history of urolithiasis: case report

ABSTRACT Bacterial resistance is a reality in both human and veterinary health, it limits the therapeutic arsenal and raises the costs of the patient’s treatment. A dog with signs of cystitis received treatment with 5mg/kg enrofloxacin at three consecutive times, with low effectiveness. The presence of urethral uroliths was identified and urohydropulsion was done. The animal presented a new obstruction, for which a cystotomy was performed, but continued with signs of infection. Uroculture and antimicrobial susceptibility test were then performed. Escherichia coli was identified, which was resistant to 13 antibiotics, being sensitive only to piperacillin-tazobactam and amikacin. In the screening test for β-lactamase, the production of ESβL was detected. The qPCR indicated the presence of the bla CTXm, bla DHA, bla OXA, bla IMP, bla TEM, bla GIM, bla SIM, bla SPM and bla SME genes, which may lead to a phenotypic resistance profile for ampicillin, amoxicillin-clavulanate, aztreonam, cefepime cefoxitin, cefuroxime, ceftazidime, ceftriaxone, imipenem, and piperacillin-tazobactam. This case reaffirms the value that laboratory analysis adds to the diagnosis and treatment of cystitis and urolithiasis, which can define the direction of evolution of the prognosis and the speed at which the patient's health will be restored.

IncN3 and IncHI2 plasmids with an In1763 integron carrying bla IMP-1 in carbapenem-resistant Enterobacterales clinical isolates from the UK.

Introduction. Imipenemase (IMP) carbapenemase genes are relatively rare among Enterobacterales in the UK. Emergence in multiple hospitals, in different strains and species, prompted an investigation into their genetic context.Aim. Our goal was to identify and describe the elements carrying bla IMP genes in a variety of Enterobacterales from five hospitals in the UK.Methodology. Long-read nanopore sequencing was carried out on 18 IMP-positive isolates belonging to 6 species. The locations of the bla IMP genes and other associated genetic elements were identified.Results. Ten out of 18 isolates carried bla IMP-1 on an IncN3 plasmid (52-57 kb) in an In1763 class 1 integron. These plasmids also contained genes encoding type IV secretion and conjugal transfer proteins. Five out of 18 isolates carried bla IMP-1 in the same In1763 integron in much larger IncHI2 plasmids. A further isolate carried the In1763 integron in a chromosomally located plasmid fragment. Two isolates carried bla IMP-4 in IncHI2 plasmids. The isolates included three representatives of sequence type 20 of Klebsiella pneumoniae, with one carrying a distinct plasmid from the other two.Conclusion. Highly similar IncN3 plasmids were found in a range of Enterobacterales, mostly K. pneumoniae and the Enterobacter cloacae complex, from three of four London hospitals, with the same In1763 integron carrying bla IMP-1 also being found in IncHI2 plasmids and chromosomally. These plasmids carried multiple elements facilitating self-transmission. Strain typing alone was not sufficient to investigate cross-infection among this set of isolates, many of which appeared to be unrelated until plasmid analysis was undertaken, and vice versa.

Prevalence of bla<sub>VIM</sub>, bla<sub>IMP</sub> and bla<sub>NDM</sub> Genes in Carbapenem Resistant Pseudomonas Aeruginosa Isolated from Different Clinical Infections in Diyala, Iraq

The study aimed to determine the prevalence of bla-genes (bla VIM , bla IMP and bla NDM ) encoding MBLs among the isolates of P. aeruginosa, which were recovered from various clinical samples from hospitalized patients in Diyala hospitals. This study was carried out during the period from February 2018 to August 2018. Out of 326 specimens, 81 isolates of P. aeruginosa were recovered. All isolates were tested toward the different class of clinically important antipseudomonal agents(18) by using agar diffusion method. The results of resistance were as following: piperacillin 74.07, ticarcillin 85.18%, Amoxicillin-Clavulanic acid 93.82%, Ticarcillin/clavulanic acid 71.60%, ceftriaxone 87.65%, cefotaxime 85.18% and ceftazidime 75.30%, cefepime 80.24%, streptomycin 90.12%, gentamicin 85.18%, tobramycin 65.43%, amikacin 56.79%, ciprofloxacin 67.90%, levofloxacin 72.83%, oflaxacin 69.13%, Aztreonam 50.61%, Imipenem 11.11% and Meropenem 23.45%.In this investigation, antibiotic susceptibility testing of the P. aeruginosa isolates showed that 20(24.69%), 25(30.8%), 27(33.33%), and 9(11.11%) of the isolates were MDS, MDR, XDR and PDR, respectively. Based on the results from susceptibility testing, 19 (23.45%) of P. aeruginosa isolates were found to be resistant to at least one of carbapenems. Out of 19 of carbapenem resistant P. aeruginosa isolates, 16 (84.21%) were found to produce MBL. Among 16 phenotypic Metallo β-lactamase isolates the results achieved by using PCR revealed that 9 (56.25%) isolates have bla VIM genes, while 4 (25%) isolates carried bla NDM genes. No bla IMP was detected among carbapenem resistant strains in this study.

Prevalence of Klebsiella pneumoniae carbapenemase - and New Delhi metallo-beta-lactamase-positive K. pneumoniae in Sergipe, Brazil, and combination therapy as a potential treatment option.

INTRODUCTION:Carbapenem-resistant Klebsiella pneumoniae infection lacks treatment options and is associated with prolonged hospital stays and high mortality rates. The production of carbapenemases is one of the most important factors responsible for this multi-resistance phenomenon.METHODS:In the present study, we analyzed the presence of genes encoding carbapenemases in K. pneumoniae isolates circulating in one of the public hospitals in the city of Aracaju, Sergipe, Brazil. We also determined the best combination of drugs that display in vitro antimicrobial synergy. First, 147 carbapenem-resistant K. pneumoniae isolates were validated for the presence of blaKPC, bla GES, bla NDM, bla SPM, bla IMP, bla VIM, and bla OXA-48 genes using multiplex polymerase chain reaction. Thereafter, using two isolates (97 and 102), the role of double and triple combinational drug therapy as a treatment option was analyzed.RESULTS:Seventy-four (50.3%) isolates were positive for bla NDM, eight (5.4%) for bla KPC, and one (1.2%) for both bla NDM and bla KPC. In the synergy tests, double combinations were better than triple combinations. Polymyxin B and amikacin for isolate 97 and polymyxin B coupled with meropenem for isolate 102 showed the best response.CONCLUSIONS:Clinicians in normal practice use multiple drugs to treat infections caused by multi-resistant microorganism; however, in most cases, the benefit of the combinations is unknown. In vitro synergistic tests, such as those described herein, are important as they might help select an appropriate multi-drug antibiotic therapy and a correct dosage, ultimately reducing toxicities and the development of antibiotic resistance.