First report of NDM-1-producing Acinetobacter baumannii sequence type 25 in Brazil

Carbapenem Resistance in Acinetobacter calcoaceticus-baumannii Complex Isolates From Kathmandu Model Hospital, Nepal, Is Attributed to the Presence of bla OXA-23-like and bla NDM-1 Genes

The Acinetobacter calcoaceticus-baumannii (ACB) complex, also known as ACB complex, consists of four bacterial species that can cause opportunistic infections in humans, especially in hospital settings. Conventional therapies for susceptible strains of the ACB complex include broad-spectrum cephalosporins, β-lactam/β-lactamase inhibitors, and carbapenems. Unfortunately, the effectiveness of these antibiotics has declined due to increasing rates of resistance. The predominant resistance mechanisms identified in the ACB complex involve carbapenem-resistant (CR) oxacillinases and metallo-β-lactamases (MBLs). This research, conducted at Kathmandu Model Hospital in Nepal, sought to identify genes associated with CR, specifically blaNDM-1, blaOXA-23-like, and blaOXA-24-like genes in carbapenem-resistant Acinetobacter calcoaceticus-baumannii (CR-ACB) complex. Additionally, the study is aimed at identifying the ACB complex through the sequencing of the 16s rRNA gene. Among the 992 samples collected from hospitalized patients, 43 (approximately 4.334%) tested positive for the ACB complex. These positive samples were mainly obtained from different hospital units, including intensive care units (ICUs); cabins; and neonatal, general, and maternity wards. The prevalence of infection was higher among males (58.14%) than females (41.86%), with the 40-50 age group showing the highest infection rate. In susceptibility testing, colistin and polymyxin B exhibited a susceptibility rate of 100%, whereas all samples showed resistance to third-generation cephalosporins. After polymyxins, gentamicin (30.23%) and amikacin (34.88%) demonstrated the highest susceptibility. A substantial majority (81.45%) of ACB complex isolates displayed resistance to carbapenems, with respiratory and pus specimens being the primary sources. Polymerase chain reaction (PCR) revealed that the primary CR gene within the ACB complex at this hospital was bla OXA-23-like, followed by bla NDM-1. To ensure the accuracy of the phenotypic assessment, 12 samples were chosen for 16s rRNA sequencing using Illumina MiSeq™ to confirm that they are Acinetobacter species. QIIME 2.0 analysis confirmed all 12 isolates to be Acinetobacter species. In the hospital setting, a substantial portion of the ACB complex carries CR genes, rendering carbapenem ineffective for treatment.

Antimicrobial resistance genes harbored in invasive Acinetobacter calcoaceticus-baumannii complex isolated from Korean children during the pre-COVID-19 pandemic periods, 2015-2020

Background

Acinetobacter baumannii (AB) has emerged as one of the most challenging pathogens worldwide, causing invasive infections in the critically ill patients due to their ability to rapidly acquire resistance to antibiotics. This study aimed to analyze antibiotic resistance genes harbored in AB and non-baumannii Acinetobacter calcoaceticus-baumannii (NB-ACB) complex causing invasive diseases in Korean children.

Methods

ACB complexes isolated from sterile body fluid of children in three referral hospitals were prospectively collected. Colistin susceptibility was additionally tested via broth microdilution. Whole genome sequencing was performed and antibiotic resistance genes were analyzed.

Results

During January 2015 to December 2020, a total of 67 ACB complexes were isolated from sterile body fluid of children in three referral hospitals. The median age of the patients was 0.6 (interquartile range, 0.1-7.2) years old. Among all the isolates, 73.1% (n=49) were confirmed as AB and others as NB-ACB complex by whole genome sequencing. Among the AB isolates, only 22.4% susceptible to carbapenem. In particular, all clonal complex (CC) 92 AB (n=33) showed multi-drug resistance, whereas 31.3% in non-CC92 AB (n=16) (P<0.001). NB-ACB showed 100% susceptibility to all classes of antibiotics except 3rd generation cephalosporin (72.2%). The main mechanism of carbapenem resistance in AB was the bla oxa23 gene with ISAba1 insertion sequence upstream. Presence of pmr gene and/or mutation of lpxA/C gene were not correlated with the phenotype of colistin resistance of ACB. All AB and NB-ACB isolates carried the abe and ade multidrug efflux pumps.

Conclusions

In conclusion, monitoring and research for resistome in ACB complex is needed to identify and manage drug-resistant AB, particularly CC92 AB carrying the bla oxa23 gene.

The Molecular Characterization of blaNDM-1-Positive Acinetobacter baumannii Isolated in Central Greece

The objective of the present study is to report the detection and the molecular characterization of nine blaNDM-1-positive Acinetobacter baumannii isolates, which were isolated from patients in a tertiary care hospital in Central Greece from December 2022 to August 2023. The isolates were characterized by whole genome sequencing to obtain Pasteur multilocus sequencing typing (MLST) and to identify the blaNDM-1-environment, resistome, and virulence genes content. In silico MLST analysis showed that the isolates belonged to four different clones (STs 160, 2, 85, and 2493). All strains, apart from the blaNDM-1-gene, possessed at least eight different genes, encoding resistance to various antimicrobial agents. Whole genome sequencing revealed two different structures of the blaNDM-1 environment. The first, detected in ST160 strain, was identical with the Tn125, whereas the second, found in STs 2, 85, and 2493 was associated with Tn7382. To our knowledge, after a sole strain reported in 2016 and imported by a patient hospitalized in a Libyan hospital, this is the first report of the emergence of polyclonal blaNDM-1-positive Acinetobacter baumannii in Greece. Our findings re-emphasize the need to apply diligent surveillance protocols in order to limit the horizontal transfer of the blaNDM-1 gene to other A. baumannii clones or to other recipient strains.

A 7-Year Brazilian National Perspective on Plasmid-Mediated Carbapenem Resistance in Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii Complex and the Impact of the Coronavirus Disease 2019 Pandemic on Their Occurrence

BACKGROUND

Carbapenemase production is a global public health threat. Antimicrobial resistance (AMR) data analysis is critical to public health policy. Here we analyzed carbapenemase detection trends using the AMR Brazilian Surveillance Network.

METHODS

Carbapenemase detection data from Brazilian hospitals included in the public laboratory information system dataset were evaluated. The detection rate (DR) was defined as carbapenemase detected by gene tested per isolate per year. The temporal trends were estimated using the Prais-Winsten regression model. The impact of COVID-19 on carbapenemase genes in Brazil was determined for the period 2015-2022. Detection pre- (October 2017 to March 2020) and post-pandemic onset (April 2020 to September 2022) was compared using the χ2 test. Analyses were performed with Stata 17.0 (StataCorp, College Station, TX).

RESULTS

83 282 blaKPC and 86 038 blaNDM were tested for all microorganisms. Enterobacterales DR for blaKPC and blaNDM was 68.6% (41 301/60 205) and 14.4% (8377/58 172), respectively. P. aeruginosa DR for blaNDM was 2.5% (313/12 528). An annual percent increase for blaNDM of 41.1% was observed, and a decrease for blaKPC of -4.0% in Enterobacterales, and an annual increase for blaNDM of 71.6% and for blaKPC of 22.2% in P. aeruginosa. From 2020 to 2022, overall increases of 65.2% for Enterobacterales, 77.7% for ABC, and 61.3% for P. aeruginosa were observed in the total isolates.

CONCLUSIONS

This study shows the strengths of the AMR Brazilian Surveillance Network with robust data related to carbapenemases in Brazil and the impact of COVID-19 with a change in carbapenemase profiles with blaNDM rising over the years.

Analysis of CRISPR/Cas Genetic Structure, Spacer Content and Molecular Epidemiology in Brazilian Acinetobacter baumannii Clinical Isolates

CRISPR/Cas is a molecular mechanism to prevent predatory viruses from invading bacteria via the insertion of small viral sequences (spacers) in its repetitive locus. The nature of spacer incorporation and the viral origins of spacers provide an overview of the genetic evolution of bacteria, their natural viral predators, and the mechanisms that prokaryotes may use to protect themselves, or to acquire mobile genetic elements such as plasmids. Here, we report on the CRISPR/Cas genetic structure, its spacer content, and strain epidemiology through MLST and CRISPR typing in Acinetobacter baumannii, an opportunistic pathogen intimately related to hospital infections and antimicrobial resistance. Results show distinct genetic characteristics, such as polymorphisms specific to ancestor direct repeats, a well-defined degenerate repeat, and a conserved leader sequence, as well as showing most spacers as targeting bacteriophages, and several self-targeting spacers, directed at prophages. There was a particular relationship between CRISPR/Cas and CC113 in the study of Brazilian isolates, and CRISPR-related typing techniques are interesting for subtyping strains with the same MLST profile. We want to emphasize the significance of descriptive genetic research on CRISPR loci, and we argue that spacer or CRISPR typing are helpful for small-scale investigations, preferably in conjunction with other molecular typing techniques such as MLST.

Molecular mechanisms of antibiotic resistance revisited

Antibiotic resistance is a global health emergency, with resistance detected to all antibiotics currently in clinical use and only a few novel drugs in the pipeline. Understanding the molecular mechanisms that bacteria use to resist the action of antimicrobials is critical to recognize global patterns of resistance and to improve the use of current drugs, as well as for the design of new drugs less susceptible to resistance development and novel strategies to combat resistance. In this Review, we explore recent advances in understanding how resistance genes contribute to the biology of the host, new structural details of relevant molecular events underpinning resistance, the identification of new resistance gene families and the interactions between different resistance mechanisms. Finally, we discuss how we can use this information to develop the next generation of antimicrobial therapies.

Genotypic characterization and clonal relatedness of metallo-β-lactamase-producing non-fermentative gram negative bacteria in the first 5 years of their circulation in Paraguay (2011-2015)

Pseudomonas aeruginosa and species of Acinetobacter calcoaceticus-baumanii complex are multiresistant intrahospital opportunistic pathogens, able to acquire carbapenemases and produce outbreaks with high morbidity and mortality. Pseudomonas putida has also emerged with similar characteristics. The aim of this research was to characterize the Metallo-β-lactamases (MBLs) detected by surveillance in Paraguay in the first 5 years of their circulation in hospitals. The coexistence of KPC and OXA-type carbapenemases was also investigated. 70 MBL-producing strains from inpatients were detected from clinical samples and rectal swab from 11 hospitals. The strains were identified by manual, automated, and molecular methods. Antimicrobial susceptibility was studied by Kirby-Bauer and automated methods, while colistin susceptibility was determined by broth macrodilution. MBLs were investigated by synergy with EDTA against carbapenems and PCR, and their variants by sequencing. KPC and OXA-carbapenemases were investigated by PCR. Clonality was studied by pulsed-field gel electrophoresis (PFGE). The results demonstrated the circulation of blaVIM-2 (60%), blaNDM-1 (36%), and blaIMP-18 (4%). The MBL-producing species were P. putida (45.7%), P. aeruginosa (17.2%), A. baumannii (24.3%), A. pittii (5.7%), A. nosocomialis, (4.3%) A. haemolyticus (1.4%), and A. bereziniae (1.4%). PFGE analysis showed one dominant clone for A. baumannii, a predominant clone for half of the strains of P. aeruginosa, and a polyclonal spread for P. putida. In the first 5 years of circulation in Paraguay, MBLs were disseminated as unique variants per genotype, appeared only in Pseudomonas spp. and Acinetobacter spp., probably through horizontal transmission between species and vertical by some successful clones.

Dissemination of NDM-producing bacteria in Southern Brazil

BACKGROUND

The dissemination of NDM-1 carbapenemases (New Delhi Metallo-β-lactamase) is a global public health problem, mainly in developing countries. The aim of this study was to characterize the spread of NDM-producing bacteria in the Southern Brazilian states analyzing epidemiological, molecular, and antimicrobial susceptibility aspects.

METHODS

A total of 10,684 carbapenem-resistant isolates of Enterobacterales, Pseudomonas spp. and Acinetobacter spp. obtained from several hospitals in eight cities in Southern Brazil were screened, and 486 NDM-producing bacteria were selected.

RESULTS

The incidence varied from 0.5 to 77 cases/100.000 habitants. ST11, ST15, ST340 and ST674 were the most common in K. pneumoniae. A total of 5 plasmids were identified in one K. pneumoniae strain: Col440I, Col440II, IncFIA(HI1), IncFIB(K), IncFIB(pQil)/ IncFII(K), and IncR.

CONCLUSIONS

The number of patients with NDM-producing bacteria has increased in Southern Brazil, whose gene is present in different plasmids, explaining the expansion of this enzyme.

Current status of NDM-producing Enterobacterales in Brazil: a narrative review

New Delhi metallo-β-lactamase (NDM)-producing Enterobacterales was first detected in Brazil in 2014, in a Providencia rettgeri isolate recovered from surveillance swabs in the Southern region. Since then, an increasing number of NDM enzymes have been reported in different species. Nevertheless, comprehensive data on the current epidemiology of NDM-producing Enterobacterales in Brazil are lacking. Therefore, this study reviewed the available information on the status of NDM-producing bacteria in Brazil. The main finding was the diversity of bacteria producing NDM, including Klebsiella, Enterobacter, Morganella, Proteus, Escherichia, and Providencia. Limited data on clonality are available, but a few studies report different clonal backgrounds in NDM-producing K. pneumoniae, likely indicating local outbreaks. Over the years, a rise in the number of reported strains in different locations has been verified; however, different biases may have contributed to this finding. Therefore, a national surveillance study is warranted to identify the actual prevalence and incidence of NDM-producing Enterobacterales in Brazil and their role in patient management and outcome.

Infections Due to Acinetobacter baumannii-calcoaceticus Complex: Escalation of Antimicrobial Resistance and Evolving Treatment Options

Bacteria within the genus Acinetobacter (principally A. baumannii-calcoaceticus complex [ABC]) are gram-negative coccobacilli that most often cause infections in nosocomial settings. Community-acquired infections are rare, but may occur in patients with comorbidities, advanced age, diabetes mellitus, chronic lung or renal disease, malignancy, or impaired immunity. Most common sites of infections include blood stream, skin/soft-tissue/surgical wounds, ventilator-associated pneumonia, orthopaedic or neurosurgical procedures, and urinary tract. Acinetobacter species are intrinsically resistant to multiple antimicrobials, and have a remarkable ability to acquire new resistance determinants via plasmids, transposons, integrons, and resistance islands. Since the 1990s, antimicrobial resistance (AMR) has escalated dramatically among ABC. Global spread of multidrug-resistant (MDR)-ABC strains reflects dissemination of a few clones between hospitals, geographic regions, and continents; excessive antibiotic use amplifies this spread. Many isolates are resistant to all antimicrobials except colistimethate sodium and tetracyclines (minocycline or tigecycline); some infections are untreatable with existing antimicrobial agents. AMR poses a serious threat to effectively treat or prevent ABC infections. Strategies to curtail environmental colonization with MDR-ABC require aggressive infection-control efforts and cohorting of infected patients. Thoughtful antibiotic strategies are essential to limit the spread of MDR-ABC. Optimal therapy will likely require combination antimicrobial therapy with existing antibiotics as well as development of novel antibiotic classes.

Multidrug-resistant Acinetobacter baumannii infections: looming threat in the Indian clinical setting

INTRODUCTION

The recent increase in multidrug-resistant strains of A. baumannii has increased the incidences of ventilator-associated pneumoniae, catheter-associated urinary tract infections, and central line-associated blood stream infections, together increasing hospital stay, treatment cost, and mortality. Resistance genes blaOXA and blaNDM are dominant in India. Carbapenem-resistant A. baumannii (CRAB) International clone-2 (IC-2) are rising in India. High dependency on carbapenems and last-resort combination of tigecycline and polymyxins have aggravated outcomes. Despite nursing barriers, ward closure, environmental disinfections etc for detecting and controlling transmission, MDR isolates and CRAB nosocomial outbreaks continue. Treatment cost overruns by AMR adversely affect 80% of Indians without insurance cover.

AREA COVERED

This narrative review will cover epidemiology, resistance pattern, genetic diversity, device-related infection, cost, and mortality due to multidrug-resistant and CRAB in India. A comprehensive literature search in PubMed and Google Scholar using appropriate keywords at different time points yielded relevant articles.

EXPERT OPINION

It is challenging to enforce policies to control MDR A. baumannii in India. Government and hospitals should enforce stringent infection control measures, surveillance, and antimicrobial stewardship to prevent further spread and emergence of more virulent and resistant strains. Knowledge on antibiotic resistance mechanisms can help design novel antibiotics that can evade, resistance.

The Spread of NDM-1 and NDM-7-Producing Klebsiella pneumoniae Is Driven by Multiclonal Expansion of High-Risk Clones in Healthcare Institutions in the State of Pará, Brazilian Amazon Region

Carbapenem resistance among Klebsiella pneumoniae isolates is often related to carbapenemase genes, located in genetic transmissible elements, particularly the blaKPC gene, which variants are spread in several countries. Recently, reports of K. pneumoniae isolates harboring the blaNDM gene have increased dramatically along with the dissemination of epidemic high-risk clones (HRCs). In the present study, we report the multiclonal spread of New Delhi metallo-beta-lactamase (NDM)-producing K. pneumoniae in different healthcare institutions in the state of Pará, Northern Brazil. A total of 23 NDM-producing isolates were tested regarding antimicrobial susceptibility testing features, screening of carbapenemase genes, and genotyping by multilocus sequencing typing (MLST). All K. pneumoniae isolates were determined as multidrug-resistant (MDR), being mainly resistant to carbapenems, cephalosporins, and fluoroquinolones. The blaNDM-7 (60.9%-14/23) and blaNDM-1 (34.8%-8/23) variants were detected. MLST genotyping revealed the predomination of HRCs, including ST11/CC258, ST340/CC258, ST15/CC15, ST392/CC147, among others. To conclude, the present study reveals the contribution of HRCs and non-HRCs in the spread of NDM-1 and NDM-7-producing K. pneumoniae isolates in Northern (Amazon region) Brazil, along with the first detection of NDM-7 variant in Latin America and Brazil, highlighting the need for surveillance and control of strains that may negatively impact healthcare and antimicrobial resistance.

Carbapenem Resistance among Marine Bacteria-An Emerging Threat to the Global Health Sector

The emergence of antibiotic resistance among pathogenic microorganisms is a major issue for global public health, as it results in acute or chronic infections, debilitating diseases, and mortality. Of particular concern is the rapid and common spread of carbapenem resistance in healthcare settings. Carbapenems are a class of critical antibiotics reserved for treatment against multidrug-resistant microorganisms, and resistance to this antibiotic may result in limited treatment against infections. In addition to in clinical facilities, carbapenem resistance has also been identified in aquatic niches, including marine environments. Various carbapenem-resistant genes (CRGs) have been detected in different marine settings, with the majority of the genes incorporated in mobile genetic elements, i.e., transposons or plasmids, which may contribute to efficient genetic transfer. This review highlights the potential of the marine environment as a reservoir for carbapenem resistance and provides a general overview of CRG transmission among marine microbes.

The Occurrence and Characterization of Class I, II, and III Integrons Among Carbapenemase-Producing Clinical Strains of Acinetobacter baumannii in Tehran, Iran

Background: Acinetobacter baumannii has emerged as a critical pathogen with high morbidity and mortality in long-term hospitalized patients who stay in intensive care units. Carbapenemases and integrons are two critical DNA elements that contribute to the emergence of multidrug-resistant (MDR) A. baumannii. Objectives: The current study aimed at characterization and molecular detection of class 1, 2, and 3 integrons among carbapenemase-producing A. baumannii strains recovered from a clinical setting in Tehran, Iran. Methods: A total of 65 non-replicated clinical strains were considered in this study. Class 1, 2, and 3 carbapenemase genes and clonal relatedness of the isolates were investigated by PCR assay. Results: The prevalence of carbapenemases was as follows: blaOXA23 (92.31%), blaVIM (69.23%), and blaNDM (1.54%). In addition, PCR sequencing confirmed the presence of gene cassette arrays consisting of aacA4-catB8-aadA1 (12/46, 26.09%), aadB-aadA1 (26.09%, 12/46), arr2-cm1A5 (30.43%, 14/46), and dfrA1-aadA1 (7.39%, 8/46) in class 1 integron and dfrA1-sat2 (52.94%, 9/17), and sat2-aadA1 (47.06%, 8/17) in class 2 integron. Sequence-based typing of both blaOXA-51-like and ampC revealed the following distribution of three different clone types among isolates: clonal complex (CC) 10 (46.15%, 30/65), CC2 (40%, 26/65), and CC3 (13.85%, 9/65). Statistical analysis showed that the presence of the intI1, blaOXA23, blaVIM, or blaNDM genes can significantly increase the acquiring MDR phenotypes in A. baumannii isolates. Conclusions: High prevalence of carbapenemase-producing A. baumannii harboring integrons is alarming public health. It seems that class 1 integron can be served as a predictive biomarker for the presence of MDR phenotypes in the clinical setting. However, integrons do not carry carbapenemases in these strains.

NDM-1-encoding plasmid in Acinetobacter chengduensis isolated from coastal water

BACKGROUND

Acinetobacter spp. may cause difficult-to-treat nosocomial infections due to acquisition of carbapenemases, including New Delhi metallo-β-lactamase (NDM). This genus has been pointed out as a possible actor in the early dissemination of bla_NDM, and this gene has been documented in a variety of species.

OBJECTIVE

Here we describe an Acinetobacter chengduensis (isolate FL51) carrying bla_NDM recovered from coastal water in Brazil.

METHODS

In vitro techniques included antimicrobial susceptibility and minimum inhibitory concentration tests, PCR, plasmid profile and matting-out/transformation assays. In silico approaches comprised comparative genomic analyses using appropriate databases.

RESULTS

FL51 grew at room temperature in a variety of culture media, excluding MacConkey. It showed resistance to all beta-lactams tested and to ciprofloxacin. bla_NDM-1 was identified, and a single replicon was observed in plasmid profile. In silico DNA hybridization revealed Acinetobacter FL51 as being Acinetobacter chengduensis. bla_NDM-1 was flanked upstream by ISAba14-aphA6-ISAba125 and downstream by ble_MBL-trpF-Δtat, inserted in a 41,068 bp non typeable plasmid named pNDM-FL51. This replicon showed high coverage and identity with other sequences present in plasmids deposited on the GenBank database, recovered almost exclusively from Acinetobacter spp., associated with hospital settings and animal sources.

CONCLUSION

We described a recently described environmental Acinetobacter species carrying a plasmid-borne bla_NDM associated with a Tn125-like structure. Our findings suggest that replicon may play an important role in bla_NDM dissemination among distinct settings within this genus and may support the theory of bla_NDM emergence from an environmental Acinetobacter.

A New Twist: The Combination of Sulbactam/Avibactam Enhances Sulbactam Activity against Carbapenem-Resistant Acinetobacter baumannii (CRAB) Isolates

An increasing number of untreatable infections are recorded every year. Many studies have focused their efforts on developing new β-lactamase inhibitors to treat multi-drug resistant (MDR) isolates. In the present study, sulbactam/avibactam and sulbactam/relebactam combination were tested against 187 multi-drug resistant (MDR) Acinetobacter clinical isolates; both sulbactam/avibactam and sulbactam/relebactam restored sulbactam activity. A decrease ≥2 dilutions in sulbactam MICs was observed in 89% of the isolates when tested in combination with avibactam. Sulbactam/relebactam was able to restore sulbactam susceptibility in 40% of the isolates. In addition, the susceptibility testing using twenty-three A. baumannii AB5075 knockout strains revealed potential sulbactam and/or sulbactam/avibactam target genes. We observed that diazabicyclooctanes (DBOs) β-lactamase inhibitors combined with sulbactam restore sulbactam susceptibility against carbapenem-resistant Acinetobacter clinical isolates. However, relebactam was not as effective as avibactam when combined with sulbactam. Exploring novel combinations may offer new options to treat Acinetobacter spp. infections, especially for widespread oxacillinases and metallo-β-lactamases (MBLs) producers.

The Experience of Implementing a National Antimicrobial Resistance Surveillance System in Brazil

Antimicrobial resistance (AMR) is a major public health threat of global proportions, which has the potential to lead to approximately ten million deaths per year by 2050. Pressured by this wicked problem, in 2014, the World Health Organization launched a call for member states to share AMR data through the implementation of the Global Antimicrobial Resistance Surveillance System (GLASS), to appropriately scale and monitor the general situation world-widely. In 2017, Brazil joined GLASS and, in 2018, started its own national antimicrobial surveillance program (BR-GLASS) to understand the impact of resistance in the country. We compiled data obtained from the complete routine of three hospitals' microbiology labs during the year of 2018. This pilot data sums up to 200,874 antimicrobial susceptibility test results from 11,347 isolates. It represents 119 different microorganisms recovered from 44 distinct types of clinical samples. Specimens came from patients originating from 301 Brazilian cities, with 4,950 of these isolates from presumed Healthcare-Associated Infections (HAIs) and the other 6,397 community-acquired cases. The female population offered 58% of the collected samples, while the other 42% were of male origin. The urinary tract was the most common topography (6,372/11,347 isolates), followed by blood samples (2,072/11,347). Gram-negative predominated the bacterial isolates: Escherichia coli was the most prevalent in general, representing 4,030 isolates (89.0% of these from the urinary tract). Coagulase-negative Staphylococci were the most prevalent bacteria in blood samples. Besides these two species, the ESKAPE group have consolidated their prevalence. Regarding drug susceptibility results, 141,648 (70.5%) were susceptible, 9,950 (4.9%) intermediate, and 49,276 (24.5%) resistant. Acinetobacter baumannii was the most worrisome microorganism, with 65.3% of the overall antimicrobial susceptibility tests showing resistance, followed by ESBL-producing Klebsiella pneumoniae, with a global resistance rate of 59%. Although this is a pilot project (still limited to one state), this database shows the importance of a nation-wide surveillance program,[153mm][-12mm] Q14 especially considering it already had patients coming from 301 distinct counties and 18 different states. The BR-GLASS Program is an ongoing project that intends to encompass at least 95 hospitals distributed in all five geographical regions in Brazil within the next 5 years.

Genomic Analysis of two NDM-1 Providencia stuartii Strains Recovered from a Single Patient

In the last years, an increasing number of untreatable infections caused by drug-resistant microbes have impacted the health care system. Worldwide, infections caused by carbapenem-resistant (CR) Gram-negative bacilli have dramatically increased. Among the CR-Gram-negative bacilli, those producing carbapenemases, such as NDM-1, are the main concern. Different Enterobacterales harboring NDM-1 have been reported lately. Providencia stuartii, a member of the Morganellaceae family, is ubiquitous in the environment, but is also known to cause nosocomial infections. Here we describe the genomic analysis of two NDM-1- producing P. stuartii strains recovered from the same patient as well as other carbapenem resistant strains recovered from the same hospital. As a result of the genomic analysis thirteen resistance genes, including three to β-lactams (bla_OXA-1, bla_TEM-1, bla_NDM-1), four to aminoglycosides (aphA6, aac(3)-IId, aac(2')-Ia, aac(6')-Ib-cr5), one to sulfonamides (sul1), two to chloramphenicol (catB3, catA3), one to rifampicin, one to bleomycin (ble), and one to tetracycline (tet(B)) were found. Moreover, a variety of mobile genetic elements, such as insertion sequences, plasmids and phage- related sequences, were found within P. stuartii genomes. The spread of carbapenem-resistant isolates remains a significant clinical and public health concern. Therefore, we considered that the detection of CR isolates is an essential step in addressing this problem.

Novel ST1465/CC216 Nosocomial Lineage of Carbapenem-Resistant Acinetobacter baumannii Harboring an Unusual Plasmid Carrying blaNDM-1 Gene

This study used whole-genome sequencing to analyze the first case of NDM-1-producing Acinetobacter baumannii belonging to the novel sequence type 1465/CC216 recovered in Brazil. The study identified an unusual plasmid carrying bla_NDM-1 gene, in which some genes of the Tn125 transposon were lost. Besides, on the chromosome, the strain reported here presented bla_OXA-106 gene, a variant of bla_OXA-51 gene, and bla_ADC-25 with ISAba1 upstream. The isolation of new STs of A. baumannii carrying bla_NDM-1 genes elicits our concerns about the possible spread of these genes among clinically relevant bacteria.

Diversity and Genetic Basis for Carbapenem Resistance in a Coastal Marine Environment

Resistance to the "last-resort" antibiotics, such as carbapenems, has led to very few antibiotics being left to treat infections by multidrug-resistant bacteria. Spread of carbapenem resistance (CR) has been well characterized for the clinical environment. However, there is a lack of information about its environmental distribution. Our study reveals that CR is present in a wide range of Gram-negative bacteria in the coastal seawater environment, including four phyla, eight classes, and 30 genera. These bacteria were likely introduced into seawater via stormwater flows. Some CR isolates found here, such as Acinetobacter junii, Acinetobacter johnsonii, Brevundimonas vesicularis, Enterococcus durans, Pseudomonas monteilii, Pseudomonas fulva, and Stenotrophomonas maltophilia, are further relevant to human health. We also describe a novel metallo-β-lactamase (MBL) for marine Rheinheimera isolates with CR, which has likely been horizontally transferred to Citrobacter freundii or Enterobacter cloacae In contrast, another MBL of the New Delhi type was likely acquired by environmental Variovorax isolates from Escherichia coli, Klebsiella pneumoniae, or Acinetobacter baumannii utilizing a plasmid. Our findings add to the growing body of evidence that the aquatic environment is both a reservoir and a vector for novel CR genes.IMPORTANCE Resistance against the "last-resort" antibiotics of the carbapenem family is often based on the production of carbapenemases, and this has been frequently observed in clinical samples. However, the dissemination of carbapenem resistance (CR) in the environment has been less well explored. Our study shows that CR is commonly found in a range of bacterial taxa in the coastal aquatic environment and can involve the exchange of novel metallo-β-lactamases from typical environmental bacteria to potential human pathogens or vice versa. The outcomes of this study contribute to a better understanding of how aquatic and marine bacteria can act as reservoirs and vectors for CR outside the clinical setting.

Distinct Mechanisms of Dissemination of NDM-1 Metallo-β-Lactamase in Acinetobacter Species in Argentina

A 4-year surveillance of carbapenem-resistant Acinetobacter spp. isolates in Argentina identified 40 strains carrying bla _NDM-1 Genome sequencing revealed that most were Acinetobacter baumannii, whereas seven represented other Acinetobacter spp. The A. baumannii genomes were closely related, suggesting recent spread. bla _NDM-1 was located in the chromosome of A. baumannii strains and on a plasmid in non-A. baumannii strains. A resistance gene island carrying bla _PER-7 and other resistance determinants was found on a plasmid in some A. baumannii strains.

Role of plasmid carrying bla NDM in mediating antibiotic resistance among Acinetobacter baumannii clinical isolates from Egypt

We investigated antibiotic resistance levels among bla_NDM-positive (n = 9) and -negative (n = 65) A. baumannii clinical isolates collected in 2010 and 2015 from Alexandria Main University Hospital, Egypt using disc diffusion and minimum inhibitory concentration (MIC) determination. Plasmids from bla_NDM-positive isolates were transformed into a carbapenem-susceptible A. baumannii (CS-AB) isolate to assess the role of plasmid transfer in mediating carbapenem resistance. Imipenem, meropenem, and ertapenem MIC90 values against bla_NDM-positive isolates were 128, > 256, and 256 µg/mL, respectively. Plasmid isolation and polymerase chain reaction revealed that bla_NDM was plasmid mediated. The plasmids were electroporated into the cells of a CS-AB isolate at an efficiency of 1.3 × 10^–8 to 2.6 × 10^–7, transforming them to bla_NDM-positive carbapenem-resistant cells with an imipenem MIC increase of 256-fold. In addition to carbapenem resistance, the bla_NDM-positive isolates also exhibited higher levels of cephalosporins, tetracycline, aminoglycosides, fluoroquinolones, and colistin resistance than the bla_NDM-negative isolates. Acquisition of bla_NDM-carrying plasmids dramatically increased imipenem resistance among A. baumannii isolates. Intriguingly, bla_NDM-positive isolates also showed a high degree of resistance to antibiotics of different classes. The potential co-existence of different resistance determinants on A. baumannii plasmids and their possible transfer owing to the natural competence of the pathogen are especially alarming. More effective infection control and antibiotic stewardship programs are needed to curb the spread and treat such infections in both hospital and community settings.

Development of multiplex PCR for rapid detection of metallo-β-lactamase genes in clinical isolates of Acinetobacter baumannii

BACKGROUND AND OBJECTIVES

Acinetobacter baumannii has been known as a major pathogen causing nosocomial infections. The aim of this study was to develop multiplex PCR for rapid and simultaneous detection of metallo-β-lactamase (MBL) genes in clinical isolates of A. baumannii.

MATERIALS AND METHODS

In this study, we used three sets of primers to amplify the MBL genes including bla _OXA-48 , bla _OXA-23 and bla _NDM . The multiplex PCR assay was optimized for rapid and simultaneous detection of MBL genes in A. baumannii strains recovered from clinical samples.

RESULTS

A. baumannii strains recovered from clinical samples were subjected to the study. The multiplex PCR produced 3 bands of 501 bp for bla _OXA-23 , 744 bp for bla _OXA-48 and 623 bp for bla _NDM genes. In addition to, no any cross-reactivity was observed in multiplex PCR.

CONCLUSION

Based on obtained data, the multiplex PCR had a good specificity without any cross reactivity and it appears that the multiplex PCR is reliable assay for simultaneous detection of MBL genes in A. baumannii strains.

First Report of New Delhi Metallo-β-Lactamase Carbapenemase-Producing Acinetobacter baumannii in Peru

Here we report the first incidence of New Delhi metallo-β-lactamase (NDM-1)-producing Acinetobacter baumannii in Peru, identified via a strain-based nosocomial surveillance project carried out in Lima and Iquitos. The bla _NDM-1 gene was detected by multiplex polymerase chain reaction (PCR) and confirmed by loci sequencing. Acinetobacter baumannii is a nearly ubiquitous and promiscuous nosocomial pathogen, and the acquisition of bla _NDM-1 by A. baumannii may facilitate an increase in the prevalence of this important resistance marker in other nosocomial pathogens.

Molecular Surveillance of Multidrug-Resistant Acinetobacter baumannii

Acinetobacter baumannii, a bacterial strain which demonstrates an elevated wide range multidrug resistance to commonly prescribed antibiotics, has been linked to recent major global outbreaks, raising a major clinical concern. Its reduced antibiotic susceptibility is closely related to the acquisition of a potent carbapenemase and/or intrinsic gene "over expression" through insertion sequences. Hence, this study aimed at investigating the antimicrobial susceptibility and molecular mechanisms underlying β-lactam resistance in A. baumannii, isolated at an academic medical centre. To understand the basis of resistance, 103 multidrug-resistant (MDR) A. baumannii isolates were collected, their antibiotic susceptibility was tested phenotypically, and then molecular analyses were performed, by testing a range of commonly encountered carbapenemases-OXA-51, OXA-23, NDM, VIM, and KPC. All strains demonstrated pan-resistance to most of the advanced antibiotics tested, including piperacillin/tazobactam, ceftazidime, cefepime, and ciprofloxacin. Moreover, majority of isolates exhibited resistance to imipenem (98.1%) and trimethoprim (90.3%). Approximately 50% of the strains showed meropenem, amikacin, and gentamycin resistance; however, lower resistance rate to tigecycline (4.9%) was noted. Moreover, isolates contained potent carbapenemases such as the intrinsic OXA-51 (89.3%), as well as the acquired resistant genes OXA-23 (68.9%), NDM (84.5%), and VIM (88.3%). The insertion sequence element ISAba1 was only detected in 35.9% of the strains. Potent resistant genes known to be carried on mobile genetic elements that aid the spread of highly resistant phenotypes were observed in a majority of isolates. These findings enforce the need for vigilant infection control measures and continuous surveillance.

High rate of detection of OXA-23-producing Acinetobacter from two general hospitals in Brazil

INTRODUCTION

In recent decades, the prevalence of carbapenem-resistant Acinetobacter isolates has increased, and the production of oxacillinase (OXA)-type carbapenemases is the main mechanism underlying resistance. We evaluated OXA production from 114 Acinetobacter isolates collected between March and December 2013 from different clinical specimens of patients in two hospitals (Hospital 1 [n = 61] and Hospital 2 [n = 53]) located in Niterói, Rio de Janeiro, Brazil. We also evaluated the genetic diversity of OXA-producing isolates.

METHODS

All the isolates were identified through the automated system Vitek II and matrix-assisted laser desorption ionization-time of flight mass spectrometry MALDI-TOF MS as belonging to the A. baumannii-A. calcoaceticuscomplex. Antimicrobial susceptibility profiles were verified through agar diffusion tests. The presence of OXA-encoding genes was confirmed by PCR. The genetic diversity of isolates positive for carbapenemase production was analyzed through pulsed-field gel electrophoresis.

RESULTS

There was a high rate of resistance to carbapenems in the isolates (imipenem: 96%; meropenem: 92%) from both hospitals. Moreover, a high percentage (95.6%) of OXA-23-positive isolates was observed for both hospitals, indicating that this was the main mechanism of carbapenem-resistance among the studied population. In addition, most isolates (96.5%) were positive for bla OXA-51. A high genetic diversity and a few major genotypes were found among the OXA-23-positive isolates analyzed. Only intra-hospital dissemination was observed.

CONCLUSIONS

The elevated dissemination of bla OXA-23-like observed among Acinetobacter isolates from both the studied hospitals highlights the need for continuous epidemiological surveillance in these institutions.

Resistome and a Novel blaNDM-1-Harboring Plasmid of an Acinetobacter haemolyticus Strain from a Children's Hospital in Puebla, Mexico

Acinetobacter calcoaceticus-baumannii complex isolates have been frequently associated with hospital and community infections, with A. baumannii being the most common. Other Acinetobacter spp. not belonging to this complex also cause infections in hospital settings, and the incidence has increased over the past few years. Some species of the Acinetobacter genus possess a great diversity of antibiotic resistance mechanisms, such as efflux pumps, porins, and resistance genes that can be acquired and disseminated by mobilizable genetic elements. By means of whole-genome sequencing, we describe in the clinical Acinetobacter haemolyticus strain AN54 different mechanisms of resistance that involve bla_OXA-265, bla_NDM-1, aphA6, aac(6’)-Ig, and a resistance-nodulation-cell division-type efflux pump. This strain carries six plasmids, of which the plasmid pAhaeAN54e contains bla_NDM-1 in a Tn125-like transposon that is truncated at the 3′ end. This strain also has an insertion sequence IS91 and seven genes encoding hypothetical proteins. The pAhaeAN54e plasmid is nontypable and different from other plasmids carrying bla_NDM-1 that have been reported in Mexico and other countries. The presence of these kinds of plasmids in an opportunistic pathogen such as A. haemolyticus highlights the role that these plasmids play in the dissemination of antibiotic resistance genes, especially against carbapenems, in Mexican hospitals.

Earliest identification of New Delhi metallo-β-lactamase 1 (NDM-1) in Acinetobacter pittii in Brazil

We report the occurrence in Brazil of the bla NDM-1 gene in Acinetobacter pittii, prior to the previously described first reports regarding the species Providencia rettgeri and Enterobacter hormaechei. Clinical isolates were investigated by polymerase chain reaction followed by bidirectional sequencing, and species was confirmed by 16S rDNA sequencing and matrix-assisted laser desorption-ionization time-of-flight spectrometry. A. pittii carrying bla NDM-1 was confirmed in a patient with no national or international travel history, or transfer from another hospital. The findings warn of the possibility of silent spread of bla NDM-1 to the community.

Diversity of metallo-β-lactamase-encoding genes found in distinct species of Acinetobacter isolated from the Brazilian Amazon Region

BACKGROUND

The multidrug resistance (MDR) phenotype is frequently observed in Acinetobacter baumannii, the most clinically relevant pathogenic species of its genus; recently, other species belonging to the A. calcoaceticus-A. baumannii complex have emerged as important MDR nosocomial pathogens.

OBJECTIVES

The present study aimed to verify the occurrence of metallo-β-lactamase genes among distinct Acinetobacter species in a hospital located in the Brazilian Amazon Region.

METHODS

Antimicrobial susceptibility profiles were determined by broth microdilution. The genetic relationships among these isolates were assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Pyrosequencing reads of plasmids carrying the bla_NDM-1 gene were generated using the Ion Torrent™ platform sequencing.

FINDINGS

A total of six isolates carried bla_NDM-1: A. baumannii (n = 2), A. nosocomialis (n = 3), and A. pittii (n = 1); three carried bla_IMP-1: A. baumannii, A. nosocomialis, and A. bereziniae. Resistance to colistin was observed for an NDM-1-producing A. nosocomialis isolate. Diverse PFGE patterns and sequence types were found among A. nosocomialis and A. baumannii isolates. The bla_NDM-1 sequence was inserted in a Tn125 transposon, while the bla_IMP-1 was found as a gene cassette of the class 1 integron In86.

MAIN CONCLUSIONS

To the best of our knowledge, this is the first report describing the dissemination of bla_NDM-1 among distinct Acinetobacter species recovered from the same hospital in South America.

Distribution of Clinical NDM-1-Producing Gram-Negative Bacteria in Brazil

New Delhi metallo-β-lactamase (NDM)-producing bacteria have been identified at a worrying rate in Brazil since 2013. Owing to the need to understand the extent of their spread, this study reports the dissemination of bla_NDM in different species of Gram-negative bacilli in different regions and states of Brazil. A total of 81 isolates from nine states were studied, including 11 species. All isolates carried bla_NDM-1 variant and were considered multidrug resistant. Colistin and amikacin were the agents with higher activity compared with the other drugs tested. The findings indicate that the NDM-1 enzyme is already widespread in the country.

New sequence type in multidrug-resistant Klebsiella pneumoniae harboring the blaNDM-1-encoding gene in Brazil

OBJECTIVES

The aim of this study was to investigate the bla_NDM gene, pathogenic potential, and antimicrobial resistance of clinical isolates of carbapenem-resistant Klebsiella pneumoniae isolated from patients admitted to the University Hospital of Londrina between January 2014 and March 2017.

METHODS

bla_NDM-1 and virulence genes were investigated using conventional PCR methods Antimicrobial susceptibility testing was performed by disk diffusion method according to the Clinical and Laboratory Standards Institute guidelines of 2017. Clonal relationships of the New Delhi metallo-β-lactamase (NDM)-positive isolates were determined by enterobacterial repetitive intergenic consensus (ERIC)-PCR and multilocus sequence typing (MLST).

RESULTS

A total of 825 K. pneumoniae were identified, with four isolates (Kp6408, Kp6410, Kp6411, and Kp6715) presenting the bla_NDM-1 gene. All NDM-1-producing isolates showed co-production of bla_KPC-2 and bla_TEM genes and also the virulence genes kfu, entB, mrkD, and fimH. Three isolates (Kp6408, Kp6410, and Kp6715) were classified as multidrug-resistant (MDR) and one (Kp6411) as extensively drug-resistant (XDR). ERIC-PCR analyses demonstrated that the isolates shared about 60% genetic similarity. MLST revealed four different sequence types (STs), described for the first time in Brazil, with two novel STs described in this study: ST3371 and ST3372.

CONCLUSION

This study reports the identification of NDM-1 associated with KPC and virulence genes in four MDR K. pneumoniae with STs first described in Brazil.

Carbapenemases in Acinetobacter baumannii. Review of their dissemination in Latin America

Carbapenem resistance in gram-negative bacteria by production of carbapenemases is one of the most challenging issues regarding healthcare worldwide. We review the epidemiology and prevalence of carbapenemases in carbapenem-resistant Acinetobacter baumannii isolates from Latin American countries. High resistance rates to antimicrobial agents, particularly to carbapenems, are observed in this region. OXA-23 is the most widely disseminated class D-carbapenemase; it is present in all the countries of the region and is frequently associated to endemic clones CC113/CC79, CC104/CC15, CC110/ST25 and CC109/CC1. The emergence of OXA-72 and NDM-1 represents a novel finding which is observed simultaneously and without clonal relatedness in different countries, some of which are distant from one another, whereas OXA-143 is only present in Brazil. Further collaborative intraregional studies would provide a better understanding of these issues in most of the countries and thus, policies to control the spread of these isolates could be implemented.

Whole-Genome Sequence of a Colombian Acinetobacter baumannii Strain, a Coproducer of OXA-72 and OXA-255-Like Carbapenemases

Colombian Acinetobacter baumannii strain ST920 was isolated from the sputum of a 68-year-old male patient. This isolate possessed blaOXA-72 and blaOXA-255-like genes. The assembled genome contained 4,104,098 pb and 38.79% G+C content. This is the first case reported of the coproduction (blaOXA-72 and blaOXA-255-like) of carbapenem-hydrolyzing class D β-lactamases (CHDLs) in Acinetobacter baumannii.

The epidemiology of carbapenemases in Latin America and the Caribbean

INTRODUCTION

Enterobacteriaceae, Pseudomonas spp., and Acinetobacter spp. infections are major causes of morbidity and mortality, especially due to the emergence and spread of β-lactamases. Carbapenemases, which are β-lactamases with the capacity to hydrolyze or inactivate carbapenems, have become a serious concern as they have the largest hydrolytic spectrum and therefore limit the utility of most β-lactam antibiotics. Areas covered: Here, we present an update of the current status of carbapenemases in Latin America and the Caribbean. Expert commentary: The increased frequency of reports on carbapenemases in Latin America and the Caribbean shows that they have successfully spread and have even become endemic in some countries. Countries such as Brazil, Colombia, Argentina, and Mexico account for the majority of these reports. Early suspicion and detection along with implementation of antimicrobial stewardship programs in all healthcare settings are crucial for the control and prevention of carbapenemase-producing bacteria.

Insights on the Horizontal Gene Transfer of Carbapenemase Determinants in the Opportunistic Pathogen Acinetobacter baumannii

Horizontal gene transfer (HGT) is a driving force to the evolution of bacteria. The fast emergence of antimicrobial resistance reflects the ability of genetic adaptation of pathogens. Acinetobacter baumannii has emerged in the last few decades as an important opportunistic nosocomial pathogen, in part due to its high capacity of acquiring resistance to diverse antibiotic families, including to the so-called last line drugs such as carbapenems. The rampant selective pressure and genetic exchange of resistance genes hinder the effective treatment of resistant infections. A. baumannii uses all the resistance mechanisms to survive against carbapenems but production of carbapenemases are the major mechanism, which may act in synergy with others. A. baumannii appears to use all the mechanisms of gene dissemination. Beyond conjugation, the mostly reported recent studies point to natural transformation, transduction and outer membrane vesicles-mediated transfer as mechanisms that may play a role in carbapenemase determinants spread. Understanding the genetic mobilization of carbapenemase genes is paramount in preventing their dissemination. Here we review the carbapenemases found in A. baumannii and present an overview of the current knowledge of contributions of the various HGT mechanisms to the molecular epidemiology of carbapenem resistance in this relevant opportunistic pathogen.

Mobile genetic elements related to carbapenem resistance in Acinetobacter baumannii

Acinetobacter baumannii is widely recognized as an important pathogen associated with nosocomial infections. The treatment of these infections is often difficult due to the acquisition of resistance genes. A. baumannii presents a high genetic plasticity which allows the accumulation of these resistance determinants leading to multidrug resistance. It is highlighted the importance of the horizontal transfer of resistance genes, through mobile genetic elements and its relationship with increased incidence of multidrug resistant A. baumannii in hospitals. Considering that resistance to carbapenems is very important from the clinical and epidemiological point of view, the aim of this article is to present an overview of the current knowledge about genetic elements related to carbapenem resistance in A. baumannii such as integrons, transposons, resistance islands and insertion sequences.

Antimicrobial resistance profiles and oxacillinase genes in carbapenem-resistant Acinetobacter baumannii isolated from hospitalized patients in Santa Catarina, Brazil

INTRODUCTION

Carbapenems are the therapy of choice for treating severe infections caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. We aimed to assess the prevalence and antimicrobial susceptibility profiles of producers of distinct oxacillinases among nosocomial isolates of the A. calcoaceticus-A. baumannii complex in a 249-bed general hospital located in Joinville, Southern Brazil.

METHODS

Of the 139 A. baumannii clinical isolates with reduced susceptibility to carbapenems between 2010 and 2013, 118 isolates from varying anatomical sites and hospital sectors were selected for genotypic analysis. Five families of genes encoding oxacillinases, namely blaOXA-23-like, blaOXA-24-like, bla(OXA-51-like), bla(OXA-58-like), and blaOXA-143-like, were investigated by multiplex polymerase chain reaction (PCR).

RESULTS

Most (87.3%) isolates simultaneously carried the bla(OXA-23-like) and bla(OXA-51-like) genes, whereas three (2.5%) isolates harbored only blaOXA-51-like ones. The circulation of carbapenem-resistant isolates increased during the study period: from none in 2010, to 22 in 2011, 64 in 2012, and 53 in 2013.

CONCLUSIONS

Isolates carrying the bla(OXA-23-like) and bla(OXA-51-like) genes were widely distributed in the hospital investigated. Because of the worsening scenario, the implementation of preventive measures and effective barriers is needed.

Population Structure Analysis of Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates from Brazil Reveals Predominance of Clonal Complexes 1, 15, and 79

The population structure of 71 carbapenem-resistantAcinetobacter baumanniiclinical isolates from several hospitals in Brazil was investigated by ApaI pulsed-field gel electrophoresis,blaOXA-51-like subtyping, and multilocus sequence typing (Institute Pasteur scheme). In addition to the predominance of strains carryingblaOXA-23, we detected the presence ofblaOXA-72andblaOXA-231 We observed a predominance of clonal complex 1 (CC1), CC15, and CC79 and representative strains of the worldwide-disseminated international clone I.

Characterization of Tn3000, a Transposon Responsible for blaNDM-1 Dissemination among Enterobacteriaceae in Brazil, Nepal, Morocco, and India

In Enterobacteriaceae, the blaNDM genes have been found in many different genetic contexts, and a wide diversity of plasmid scaffolds bearing those genes has been found. In August 2013, we identified NDM-1-producing Escherichia coli and Enterobacter hormaechei strains from a single rectal swab sample from a patient hospitalized in Rio de Janeiro, Brazil, who had no history of travel abroad. Complete DNA sequencing using the Illumina platform and annotation of the two plasmids harboring the blaNDM-1 gene, one from each strain, showed that they belonged to incompatibility groups IncFIIK and IncX3 and harbored a novel transposon named Tn3000. Similar genetic structures have been identified among other isolates in Brazil but also on plasmids from other continents. Our findings suggest that the blaNDM-1 gene may be transmitted by Tn3000 in different parts of the world.

Draft genome sequences of three NDM-1-producing Enterobacteriaceae species isolated from Brazil

The emergence of multidrug-resistant Enterobacteriaceae strains producing carbapenemases, such as NDM-1, has become a major public health issue due to a high dissemination capacity and limited treatment options. Here we describe the draft genome of three NDM-1-producing isolates: Providencia rettgeri (CCBH11880), Enterobacter hormaechei subsp. oharae (CCBH10892) and Klebsiella pneumoniae (CCBH13327), isolated in Brazil. Besides bla^NDM-1, resistance genes to aminoglycosides [aadA1, aadA2, aac(6’)-Ib-cr] and quinolones (qnrA1, qnrB4) were observed which contributed to the multidrug resistance profile. The element ISAba125 was found associated to the bla^NDM-1 gene in all strains.

Emerging broad-spectrum resistance in Pseudomonas aeruginosa and Acinetobacter baumannii: Mechanisms and epidemiology

Multidrug resistance is quite common among non-fermenting Gram-negative rods, in particular among clinically relevant species including Pseudomonas aeruginosa and Acinetobacter baumannii. These bacterial species, which are mainly nosocomial pathogens, possess a diversity of resistance mechanisms that may lead to multidrug or even pandrug resistance. Extended-spectrum β-lactamases (ESBLs) conferring resistance to broad-spectrum cephalosporins, carbapenemases conferring resistance to carbapenems, and 16S rRNA methylases conferring resistance to all clinically relevant aminoglycosides are the most important causes of concern. Concomitant resistance to fluoroquinolones, polymyxins (colistin) and tigecycline may lead to pandrug resistance. The most important mechanisms of resistance in P. aeruginosa and A. baumannii and their most recent dissemination worldwide are detailed here.