50-kb Plasmid Research Articles

Chromium bioremediation potential of indigenous Bacillus pumillus isolated from river water of Bangladesh

Bangladesh has achieved rapid industrialization in recent years. However, many of these industries lack proper effluent treatment plant and discharge untreated effluent laden with different heavy metals into the major rives that surround these industries, affecting the environment as well as human and animal health. Aiming to develop a sustainable effluent treatment plant, a heavy metal tolerant Bacillus pumillus isolated from polluted river water of Bangladesh was studied for its chromium bioremediation potential. Reduction of hexavalent chromium using the Sdiphenylcarbazide (DPC) method showed that whole cells of the Bacillus pumillus reduced 89.5%, 75%, 73% and 45% of 1.0, 2.5, 5 and 10mg/L Cr(VI) to Cr(III), respectively. This bacterium reduced 100% of 20mg/L Cr(VI) to Cr(III) within 8 hours, in a growth associated pattern. A 20kb plasmid was detected in this Bacillus pumillus, and loss of this plasmid did not cause complete impairment of chromium tolerance capacity, though the tolerance efficiency was reduced. The Bacillus pumillus studied in the current study therefore shows its potential to develop a sustainable chromium bioremediation method.
 Bangladesh J Microbiol, Volume 38, Number 1, June 2021, pp 27-30

Characterization of a Novel Variant of the Quinolone-Resistance Gene qnrB (qnrB89) Carried by a Multi-Drug Resistant Citrobacter gillenii Strain Isolated from Farmed Salmon in Chile.

The main objective of this study was to characterize using whole-genome sequencing analysis, a new variant of the qnrB gene (qnrB89) carried by a fluoroquinolone-susceptible bacterium isolated from mucus of farmed Salmo salar fingerling in Chile. Citrobacter gillenii FP75 was identified by using biochemical tests and 16S ribosomal gene analysis. Nucleotide and amino acid sequences of the qnrB89 gene exhibited an identity to qnrB of 81.24% and 91.59%, respectively. The genetic environment of qnrB89 was characterized by the upstream location of a sequence encoding for a protein containing a heavy metal-binding domain and a gene encoding for a N-acetylmuramoyl-L-alanine amidase protein, whereas downstream to qnrB89 gene were detected the csp and cspG genes, encoding cold-shock proteins. The qnrB89 gene was located on a large chromosomal contig of the FP75 genome and was not associated with the 10-kb plasmid and class 1 integron harbored by the FP75 strain. This study reports for the first time the carriage of a qnrB gene by the C. gillenii species, and its detection in a bacterial strain isolated from farmed salmon in Chile.

Characterization of a New Transposon, Tn6696, on a blaNDM–1-Carrying Plasmid From Multidrug-Resistant Enterobacter cloacae ssp. dissolvens in China

BackgroundEnterobacter cloacae is an opportunistic pathogen which is responsible for serious nosocomial infections. A gene which plays an important role in resistance to carbapenems is the New Delhi metallo-β-lactamase 1 (NDM-1). Currently, the spread of NDM-1-producing E. cloacae strains is a serious public threat.MethodsA multidrug-resistant E. cloacae ssp. dissolvens strain CBG15936 was recovered in 2017 in Guangzhou, China. PCR, S1-pulsed-field gel electrophoresis, and Southern blotting were performed to locate the blaNDM–1 gene. Susceptibility testing and conjugation experiments were also performed. Illumina HiSeq and Nanopore sequencers were used to perform whole-genome sequencing.ResultsStrain CBG15936 belongs to ST932 and is resistant to carbapenems. The blaNDM–1 gene was found on a ∼62-kb plasmid, which has a conjugation frequency of 1.68 × 10–3 events per donor cell. Genome sequencing and analysis revealed that the NDM-1-carrying IncN1 plasmid contained a new transposon Tn6696, which consists of an intact qnrS1-carrying Tn6292 element, an inverted 8.3-kb Tn3000 remnant, ISkpn19, ΔtnpA, and IS26.ConclusionA new transposon, Tn6696, has been detected on a blaNDM–1-carrying plasmid recovered from multidrug-resistant E. cloacae ssp. dissolvens CBG15936 from China. This finding provides a new perspective regarding the potential for blaNDM–1 to undergo horizontal transfer among drug-resistant bacteria.

A prolonged multispecies outbreak of IMP-6 carbapenemase-producing Enterobacterales due to horizontal transmission of the IncN plasmid

A multispecies outbreak of IMP-6 carbapenemase-producing Enterobacterales (IMP-6-CPE) occurred at an acute care hospital in Japan. This study was conducted to understand the mechanisms of IMP-6-CPE transmission by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing and whole-genome sequencing (WGS), and identify risk factors for IMP-6-CPE acquisition in patients who underwent abdominal surgery. Between July 2013 and March 2014, 22 hospitalized patients infected or colonized with IMP-6-CPE (Escherichia coli [n = 8], Klebsiella oxytoca [n = 5], Enterobacter cloacae [n = 5], Klebsiella pneumoniae [n = 3] and Klebsiella aerogenes [n = 1]) were identified. There were diverse PFGE profiles and sequence types (STs) in most of the species except for K. oxytoca. All isolates of K. oxytoca belonged to ST29 with similar PFGE profiles, suggesting their clonal transmission. Plasmid analysis by WGS revealed that all 22 isolates but one shared a ca. 50-kb IncN plasmid backbone with blaIMP-6 suggesting interspecies gene transmission, and typing of plasmids explained epidemiological links among cases. A case-control study showed pancreatoduodenectomy, changing drains in fluoroscopy room, continuous peritoneal lavage and enteric fistula were associated with IMP-6-CPE acquisition among the patients. Plasmid analysis of isolates in an outbreak of IMP-6-CPE suggested interspecies gene transmission and helped to clarify hidden epidemiological links between cases.

Complete Genome Sequence of the Deep-Sea Bacterium Moritella marina MP-1 (ATCC 15381).

Here, the complete assembly of the Moritella marina MP-1 (ATCC 15381) genome, combining Illumina and long Nanopore reads, is presented. The gapless assembly consists of a 4.7-Mb circular chromosome and a 26-kb plasmid, with a G+C content of 40.7%, and will assist in further studies of the molecular pathways in this biotechnologically significant organism.

The complete genome sequence of Rahnella aquatilis ZF7 reveals potential beneficial properties and stress tolerance capabilities.

Rahnella aquatilis ZF7 is a plant beneficial strain isolated from Sakura tree soil with potential for biocontrol. Here, we present the complete genome sequence of R. aquatilis ZF7, which consists of one 4.49Mb circular chromosome and a 54-kb plasmid named pRAZF7. Phylogenetic analyses revealed that R. aquatilis ZF7 is much similar to the strains Rahnella sp. Y9602 and R. aquatilis HX2 than others evaluated. In this study, multiple genes encoding functions that likely contribute to plant growth promotion, biocontrol and stress tolerance were identified by comparative genome analyses, including IAA production, phosphate solubilization, antibiotic resistance and formation of Se nanoparticles (SeNPs). In addition, these functions were also confirmed by in vitro experiments. Considering its ability to form SeNPs, strain R. aquatilis ZF7 will contribute to nano-agriculture. Overall, the features of R. aquatilis ZF7 make it a high potential and competitive strain in biocontrol, and the genome data will help further studies on the mechanisms of plant growth promotion and biocontrol.

Identification of FosA8, a Plasmid-Encoded Fosfomycin Resistance Determinant from Escherichia coli, and Its Origin in Leclercia adecarboxylata.

A plasmid-located fosfomycin resistance gene, fosA8, was identified from a CTX-M-15-producing Escherichia coli isolate recovered from urine. Identification of this gene was obtained by whole-genome sequencing. It encoded FosA8, which shares 79% and 78% amino acid identity with the most closely related FosA2 and FosA1 enzymes, respectively. The fosA8 gene was located on a transferable 50-kb plasmid of IncN type encoding high-level resistance to fosfomycin. In silico analysis and cloning experiments identified fosA8 analogues (99% identity) in the genome of Leclercia decarboxylata, which is an enterobacterial species with natural resistance to fosfomycin. This finding adds L. decarboxylata to the list of enterobacterial species that are a reservoir of fosA-like genes which have been captured from the chromosome of a progenitor and are then acquired by E. coli.

Pseudomonas syringae pv. syringae Associated With Mango Trees, a Particular Pathogen Within the "Hodgepodge" of the Pseudomonas syringae Complex.

The Pseudomonas syringae complex comprises different genetic groups that include strains from both agricultural and environmental habitats. This complex group has been used for decades as a “hodgepodge,” including many taxonomically related species. More than 60 pathovars of P. syringae have been described based on distinct host ranges and disease symptoms they cause. These pathovars cause disease relying on an array of virulence mechanisms. However, P. syringae pv. syringae (Pss) is the most polyphagous bacterium in the P. syringae complex, based on its wide host range, that primarily affects woody and herbaceous host plants. In early 1990s, bacterial apical necrosis (BAN) of mango trees, a critical disease elicited by Pss in Southern Spain was described for the first time. Pss exhibits important epiphytic traits and virulence factors, which may promote its survival and pathogenicity in mango trees and in other plant hosts. Over more than two decades, Pss strains isolated from mango trees have been comprehensively investigated to elucidate the mechanisms that governs their epiphytic and pathogenic lifestyles. In particular, the vast majority of Pss strains isolated from mango trees produce an antimetabolite toxin, called mangotoxin, whose leading role in virulence has been clearly demonstrated. Moreover, phenotypic, genetic and phylogenetic approaches support that Pss strains producers of BAN symptoms on mango trees all belong to a single phylotype within phylogroup 2, are adapted to the mango host, and produce mangotoxin. Remarkably, a genome sequencing project of the Pss model strain UMAF0158 revealed the presence of other factors that may play major roles in its different lifestyles, such as the presence of two different type III secretion systems, two type VI secretion systems and an operon for cellulose biosynthesis. The role of cellulose in increasing mango leaf colonization and biofilm formation, and impairing virulence of Pss, suggests that cellulose may play a pivotal role with regards to the balance of its different lifestyles. In addition, 62-kb plasmids belonging to the pPT23A-family of plasmids (PFPs) have been strongly associated with Pss strains that inhabit mango trees. Further, complete sequence and comparative genomic analyses revealed major roles of PFPs in detoxification of copper compounds and ultraviolet radiation resistance, both improving the epiphytic lifestyle of Pss on mango surfaces. Hence, in this review we summarize the research that has been conducted on Pss by our research group to elucidate the molecular mechanisms that underpin the epiphytic and pathogenic lifestyle on mango trees. Finally, future directions in this particular plant–pathogen story are discussed.

Molecular Characterization of OXA-198 Carbapenemase-Producing Pseudomonas aeruginosa Clinical Isolates.

Carbapenemase-producing Pseudomonadaceae have increasingly been reported worldwide, with an ever-increasing heterogeneity of carbapenem resistance mechanisms, depending on the bacterial species and the geographical location. OXA-198 is a plasmid-encoded class D β-lactamase involved in carbapenem resistance in one Pseudomonas aeruginosa isolate from Belgium. In the setting of a multicenter survey of carbapenem resistance in P. aeruginosa strains in Belgian hospitals in 2013, three additional OXA-198-producing P. aeruginosa isolates originating from patients hospitalized in one hospital were detected. To reveal the molecular mechanism underlying the reduced susceptibility to carbapenems, MIC determinations, whole-genome sequencing, and PCR analyses to confirm the genetic organization were performed. The plasmid harboring the blaOXA-198 gene was characterized, along with the genetic relatedness of the four P. aeruginosa isolates. The blaOXA-198 gene was harbored on a class 1 integron carried by an ∼49-kb IncP-type plasmid proposed as IncP-11. The same plasmid was present in all four P. aeruginosa isolates. Multilocus sequence typing revealed that the isolates all belonged to sequence type 446, and single-nucleotide polymorphism analysis revealed only a few differences between the isolates. This report describes the structure of a 49-kb plasmid harboring the blaOXA-198 gene and presents the first description of OXA-198-producing P. aeruginosa isolates associated with a hospital-associated cluster episode.

Clonal Emergence of Invasive Multidrug-Resistant Staphylococcus epidermidis Deconvoluted via a Combination of Whole-Genome Sequencing and Microbiome Analyses.

Pathobionts, bacteria that are typically human commensals but can cause disease, contribute significantly to antimicrobial resistance. Staphylococcus epidermidis is a prototypical pathobiont as it is a ubiquitous human commensal but also a leading cause of healthcare-associated bacteremia. We sought to determine the etiology of a recent increase in invasive S. epidermidis isolates resistant to linezolid. Whole-genome sequencing (WGS) was performed on 176 S. epidermidis bloodstream isolates collected at the MD Anderson Cancer Center in Houston, Texas, between 2013 and 2016. Molecular relationships were assessed via complementary phylogenomic approaches. Abundance of the linezolid resistance determinant cfr was determined in stool samples via reverse-transcription quantitative polymerase chain reaction. Thirty-nine of the 176 strains were linezolid resistant (22%). Thirty-one of the 39 linezolid-resistant S. epidermidis infections were caused by a particular clone resistant to multiple antimicrobials that spread among leukemia patients and carried cfr on a 49-kb plasmid (herein called pMB151a). The 6 kb of pMB151a surrounding the cfr gene was nearly 100% identical to a cfr-containing plasmid isolated from livestock-associated staphylococci in China. Analysis of serial stool samples from leukemia patients revealed progressive staphylococcal domination of the intestinal microflora and an increase in cfr abundance following linezolid use. The combination of linezolid use plus transmission of a multidrug-resistant clone drove expansion of invasive, linezolid-resistant S. epidermidis. Our results lend support to the notion that a combination of antibiotic stewardship plus infection control measures may help to control the spread of a multidrug-resistant pathobiont.

Horizontal Dissemination of Antimicrobial Resistance Determinants in Multiple Salmonella Serotypes following Isolation from the Commercial Swine Operation Environment after Manure Application.

The aim of this study was to characterize the plasmids carrying antimicrobial resistance (AMR) determinants in multiple Salmonella serotypes recovered from the commercial swine farm environment after manure application on land. Manure and soil samples were collected on day 0 before and after manure application on six farms in North Carolina, and sequential soil samples were recollected on days 7, 14, and 21 from the same plots. All environmental samples were processed for Salmonella, and their plasmid contents were further characterized. A total of 14 isolates including Salmonella enterica serotypes Johannesburg (n = 2), Ohio (n = 2), Rissen (n = 1), Typhimurium var5- (n = 5), Worthington (n = 3), and 4,12:i:- (n = 1), representing different farms, were selected for plasmid analysis. Antimicrobial susceptibility testing was done by broth microdilution against a panel of 14 antimicrobials on the 14 confirmed transconjugants after conjugation assays. The plasmids were isolated by modified alkaline lysis, and PCRs were performed on purified plasmid DNA to identify the AMR determinants and the plasmid replicon types. The plasmids were sequenced for further analysis and to compare profiles and create phylogenetic trees. A class 1 integron with an ANT(2″)-Ia-aadA2 cassette was detected in the 50-kb IncN plasmids identified in S Worthington isolates. We identified 100-kb and 90-kb IncI1 plasmids in S Johannesburg and S Rissen isolates carrying the blaCMY-2 and tet(A) genes, respectively. An identical 95-kb IncF plasmid was widely disseminated among the different serotypes and across different farms. Our study provides evidence on the importance of horizontal dissemination of resistance determinants through plasmids of multiple Salmonella serotypes distributed across commercial swine farms after manure application.IMPORTANCE The horizontal gene transfer of antimicrobial resistance (AMR) determinants located on plasmids is considered to be the main reason for the rapid proliferation and spread of drug resistance. The deposition of manure generated in swine production systems into the environment is identified as a potential source of AMR dissemination. In this study, AMR gene-carrying plasmids were detected in multiple Salmonella serotypes across different commercial swine farms in North Carolina. The plasmid profiles were characterized based on Salmonella serotype donors and incompatibility (Inc) groups. We found that different Inc plasmids showed evidence of AMR gene transfer in multiple Salmonella serotypes. We detected an identical 95-kb plasmid that was widely distributed across swine farms in North Carolina. These conjugable resistance plasmids were able to persist on land after swine manure application. Our study provides strong evidence of AMR determinant dissemination present in plasmids of multiple Salmonella serotypes in the environment after manure application.

Multihospital Occurrence of Pan-Resistant Klebsiella pneumoniae Sequence Type 147 with an ISEcp1-Directed blaOXA-181 Insertion in the mgrB Gene in the United Arab Emirates.

The emergence of pan-resistant Klebsiella pneumoniae strains is an increasing concern. In the present study, we describe a cluster of 9 pan-resistant K. pneumoniae sequence type 147 (ST147) isolates encountered in 4 patients over nearly 1 year in 3 hospitals of the United Arab Emirates (UAE). The isolates exhibited highly similar genotypes. All produced chromosomally encoded OXA-181, and the majority also produced the NDM-5 carbapenemase. As with the previously described single isolate from the UAE, MS6671, the mgrB was disrupted by a functional, ISEcp1-driven blaOXA-181 insertion causing resistance to carbapenems. The mutation was successfully complemented with an intact mgrB gene, indicating that it was responsible for colistin resistance. blaNDM-5 was located within a resistance island of an approximately 100-kb IncFII plasmid carrying ermB, mph(A), blaTEM-1B, rmtB, blaNDM-5, sul1, aadA2, and dfrA12 resistance genes. Sequencing this plasmid (pABC143-NDM) revealed that its backbone was nearly identical to that of plasmid pMS6671E from which several resistance genes, including blaNDM-5, had been deleted. More extensive similarities of the backbone and the resistance island were found between pABC143C-NDM and the blaNDM-5-carrying IncFII plasmids of two K. pneumoniae ST147 isolates from South Korea, one of which was colistin resistant, and both also produced OXA-181. Notably, one of these strains was isolated from a patient transferred from the UAE. Our data show that this pan-resistant clone has an alarming capacity to maintain itself over an extended period of time and is even likely to be transmitted internationally.

PER-8, a Novel Extended-Spectrum β-Lactamase PER Variant, from an Acinetobacter baumannii Clinical Isolate in Nepal.

A novel PER-type extended-spectrum β-lactamase, PER-8, was identified in an Acinetobacter baumannii clinical isolate obtained in Nepal. The amino acid sequence of PER-8 has a substitution at position 39 (Gly to Glu) compared with that of PER-7. The kcat/Km ratio of PER-8 for aztreonam was lower than that of PER-7, while the kcat/Km ratio of PER-8 for imipenem was higher than that of PER-7. The genomic environment surrounding blaPER-8 was intI1 blaPSE-1qacEDI sulI ISCR1-blaPER-8gts sulI orfX on a 100-kb plasmid.

Plasmid Complement of Lactococcus lactis NCDO712 Reveals a Novel Pilus Gene Cluster.

Lactococcus lactis MG1363 is an important gram-positive model organism. It is a plasmid-free and phage-cured derivative of strain NCDO712. Plasmid-cured strains facilitate studies on molecular biological aspects, but many properties which make L. lactis an important organism in the dairy industry are plasmid encoded. We sequenced the total DNA of strain NCDO712 and, contrary to earlier reports, revealed that the strain carries 6 rather than 5 plasmids. A new 50-kb plasmid, designated pNZ712, encodes functional nisin immunity (nisCIP) and copper resistance (lcoRSABC). The copper resistance could be used as a marker for the conjugation of pNZ712 to L. lactis MG1614. A genome comparison with the plasmid cured daughter strain MG1363 showed that the number of single nucleotide polymorphisms that accumulated in the laboratory since the strains diverted more than 30 years ago is limited to 11 of which only 5 lead to amino acid changes. The 16-kb plasmid pSH74 was found to contain a novel 8-kb pilus gene cluster spaCB-spaA-srtC1-srtC2, which is predicted to encode a pilin tip protein SpaC, a pilus basal subunit SpaB, and a pilus backbone protein SpaA. The sortases SrtC1/SrtC2 are most likely involved in pilus polymerization while the chromosomally encoded SrtA could act to anchor the pilus to peptidoglycan in the cell wall. Overexpression of the pilus gene cluster from a multi-copy plasmid in L. lactis MG1363 resulted in cell chaining, aggregation, rapid sedimentation and increased conjugation efficiency of the cells. Electron microscopy showed that the over-expression of the pilus gene cluster leads to appendices on the cell surfaces. A deletion of the gene encoding the putative basal protein spaB, by truncating spaCB, led to more pilus-like structures on the cell surface, but cell aggregation and cell chaining were no longer observed. This is consistent with the prediction that spaB is involved in the anchoring of the pili to the cell.

Antimicrobial resistance and molecular subtypes of Salmonella enterica serovar Typhi isolates from Kolkata, India over a 15 years period 1998–2012

Typhoid fever, caused by Salmonella enterica serovar Typhi (S. Typhi), remains an unresolved public health problem in India. Emergence of antimicrobial resistant strains poses a great concern for typhoid treatment and influences reshaping of current S. Typhi population. We included representative S. Typhi strains (n=164) from retrospective studies, both community and hospital based, conducted at National Institute of Cholera and Enteric Diseases, Kolkata during 15 years period (1998–2012) to analyze their antimicrobial resistance (AMR) profiles, mechanism of AMR and molecular subtypes of the strains. More than 60% of the S. Typhi isolates were obtained from community based studies. During the study period, steady decline (46.4%–15.6%) in isolation of multidrug-resistant (MDR, resistant to ampicillin, chloramphenicol and co-trimoxazole) S. Typhi was noticed with parallel increase of nalidixic acid-resistant (NALR) strains (60.7%–93.8%) and ciprofloxacin resistant (CIPR) strains (0%–25%). Of 53 MDR strains, 46 (86.8%) were NALR showing decreased ciprofloxacin susceptible (DCS) (MIC for ciprofloxacin 0.12-0.5μg/ml) phenotype. Conjugative IncHI1 (230kb) and non-conjugative non-IncHI1 (180kb) plasmids were found in 23 (43.4%) and 14 (26.4%) MDR strains respectively, plasmid was absent in 16 (30.2%) MDR strains. MDR strains with or without plasmid shared the same set of resistance genes (blaTEM-1, catA1, sul1, sul2, strA and strB) and class 1 integron possessing dfrA7 gene cassette. Two S. Typhi strains harbored 50kb transferrable plasmids carrying dfrA15 and aadA1 gene cassettes in class 1 integron. The majority of the strains (135/164, 82.3%) belonged to H58 haplotype. Among the MDR isolates, fluoroquinolone resistant or combined resistant isolates (n=147), 127 (86.4%) were H58 and 20 (13.6%) belonged to non-H58. NALRS. Typhi strains with decreased susceptibility or resistance to ciprofloxacin had point mutation(s) in quinolone resistance-determining region of gyrA and parC genes. Pulsed-field gel electrophoresis showed more diversity among NALRS. Typhi than MDR strains. Results of this study generated information useful for better understanding of the disease epidemiology and its control in endemic settings.

Genome Sequences of Ralstonia insidiosa Type Strain ATCC 49129 and Strain FC1138, a Strong Biofilm Producer Isolated from a Fresh-Cut Produce-Processing Plant.

Ralstonia insidiosa is an opportunistic pathogen and a strong biofilm producer. Here, we present the complete genome sequences of R. insidiosa FC1138 and ATCC 49129. Both strains have two circular chromosomes of approximately 3.9 and 1.9 Mb and a 50-kb plasmid. ATCC 49129 also possesses a megaplasmid of approximately 318 kb.

First Occurrence of OXA-72-Producing Acinetobacter baumannii in Serbia.

Here, we characterized the first OXA-72-producing Acinetobacter baumannii isolate (designated MAL) recovered from a urine sample from a Serbian patient. Antimicrobial susceptibility testing, plasmid analysis, and whole-genome sequencing (WGS) were performed to fully characterize the resistome of the A. baumannii MAL clinical isolate. The isolate was multidrug resistant and remained susceptible only to colistin and tigecycline. PCR analysis revealed the presence of the carbapenemase OXA-72, an OXA-40 variant. Extraction by the Kieser method revealed the presence of two plasmids, and one of these, a ca. 10-kb plasmid, harbored the blaOXA-72 gene. WGS revealed 206 contigs corresponding to a genome of 3.9 Mbp in size with a G+C content of 38.8%. The isolate belonged to sequence type 492 and to worldwide clone II (WWCII). Naturally occurring β-lactamase-encoding genes (blaADC-25 and blaOXA-66) were also identified. Aminoglycoside resistance genes encoding one aminoglycoside adenyltransferase (aadA2), three aminoglycoside phosphatases (strA, strB, aphA6), and one 16S RNA methylase (armA) conferring resistance to all aminoglycosides were identified. Resistance to fluoroquinolones was likely due to mutations in gyrA, parC, and parE Of note, the resistome matched perfectly with the antibiotic susceptibility testing results.

Frequency of BKC-1-Producing Klebsiella Species Isolates.

BKC-1 is a new class A serine carbapenemase that was recently identified in Klebsiella pneumoniae clinical isolates. The principal objective of this study was to evaluate the frequency of blaBKC-1 by testing a collection of Klebsiella isolates. Only 2 of 635 Klebsiella isolates (0.3%) carried blaBKC-1 The two BKC-1-producing isolates belonged to clonal complex 442 and possessed identical pulsed-field gel electrophoresis patterns. The blaBKC-1 gene was inserted into a 10-kb plasmid that was identical to the previously reported plasmid, p60136. The BKC-producing K. pneumoniae isolates presented also possessed other mechanisms for beta-lactam resistance, such as genes encoding extended-spectrum beta-lactamases and mutations in the genes ompK35 and ompK36, encoding the major porins.

Antimicrobial resistance and class 1 integron-associated gene cassettes in Salmonella enterica serovar Typhimurium isolated from pigs at slaughter and abattoir environment

Forty-five multi-resistant Salmonella enterica subsp. enterica serovar (S.) Typhimurium isolates obtained at five pig abattoirs in Southern Brazil were characterized. Their relatedness was determined by XbaI-macrorestriction analysis. Resistance genes, integrons and plasmid-mediated quinolone resistance genes (PMQR) were investigated by PCR. Amplicons for the variable part of class 1 integrons and the quinolone resistance-determining regions (QRDR) were sequenced. Plasmids were characterized by conjugation assays and replicon typing. Eighteen XbaI-macrorestriction patterns and 19 plasmid profiles were seen. Resistance to ampicillin (blaTEM), chloramphenicol (catA1 and floR), streptomycin (strA-strB), streptomycin/spectinomycin (aadA variants), sulphonamides (sul1, sul2, sul3) and tetracyclines [tet(A) and tet(B)] were commonly found. A trimethoprim resistance gene, dfrA8, was identified on a 100-kb plasmid. Single substitutions in the QRDR of GyrA but no PMQR genes were found. Twenty-five isolates carried class 1 integrons with an aadA23 gene cassette or unusual class 1 integrons with a dfrA12-orfF-aadA27 gene cassette array. Both integrons were found on large conjugative plasmids. Salmonella plasmid-located virulence genes spvR, spvA, spvB, rck and pefA were found on an IncFIB resistance plasmid. Hybrid virulence-resistance plasmids or plasmids harbouring class 1 integrons may play a role in the maintenance and dissemination of antimicrobial resistance among S. Typhimurium in this pig production system.

Draft Genome Sequence of a Community-Associated Methicillin-Resistant Panton-Valentine Leukocidin-Positive Staphylococcus aureus Sequence Type 30 Isolate from a Pediatric Patient with a Lung Infection in Brazil.

The sequence of methicillin-resistant Staphylococcus aureus strain B6 (sequence type 30 [ST30], spa type t433, staphylococcal chromosomal cassette mec element [SCCmec] type IVc, Panton-Valentine leukocidin [PVL] positive), isolated from a pediatric patient with a lung infection in Niterói, Rio de Janeiro, Brazil, is described here. The draft genome sequence includes a 2.8-Mb chromosome, accompanied by a 20-kb plasmid containing blaZ and two small cryptic plasmids.