Identification of Three Clf-Sdr Subfamily Proteins in Staphylococcus warneri, and Comparative Genomics Analysis of a Locus Encoding CWA Proteins in Staphylococcus Species.

Coagulase-negative Staphylococcus warneri is an opportunistic pathogen that is capable of causing several infections, especially in patients with indwelling medical devices. Here, we determined the complete genome sequence of a clinical S. warneri strain isolated from the blood culture of a 1-year-old nursling patient with acute upper respiratory infection. Genome-wide phylogenetic analysis confirmed the phylogenetic relationships between S. warneri and other Staphylococcus species. Using comparative genomics, we identified three cell wall-anchored (CWA) proteins at the same locus (sdr), named SdrJ, SdrK, and SdrL, on the chromosome sequences of different S. warneri strains. Structural predictions showed that SdrJ/K/L have structural features characteristic of Sdr proteins but exceptionally contained an unusual N-terminal repeat region. However, the C-terminal repetitive (R) region of SdrJ contains a significantly larger proportion of alanine (142/338, 42.01%) than the previously reported SdrI (37.00%). Investigation of the genetic organization revealed that the sdrJ/K/L genes were always followed by one or two glycosyltransferase genes, gtfA and gtfB and were present in an ∼56 kb region bordered by a pair of 8 bp identical direct repeats, named Sw-Sdr. This region was further found to be located on a 160-kb region subtended by a pair of 160-bp direct repeats along with other virulence genes and resistance genes. Sw-Sdr contained a putative integrase that was probably a remnant of a functional integrase. Evidence suggests that Sw-Sdr is improbably an efficient pathogenicity island. A large-scale investigation of Staphylococcus genomes showed that sdr loci were a potential hotspot of insertion sequences (ISs), which could lead to intraspecific diversity at these loci. Our work expanded the repository of Staphylococcus Sdr proteins, and for the first time, we established the connection between sdr loci and phylogenetic relationships and compared the sdr loci in different Staphylococcus species, which provided large insights into the genetic environment of CWA genes in Staphylococcus.

Genomic Analysis of Delftia tsuruhatensis Strain TR1180 Isolated From A Patient From China With In4-Like Integron-Associated Antimicrobial Resistance.

Delftia tsuruhatensis has become an emerging pathogen in humans. There is scant information on the genomic characteristics of this microorganism. In this study, we determined the complete genome sequence of a clinical D. tsuruhatensis strain, TR1180, isolated from a sputum specimen of a female patient in China in 2019. Phylogenetic and average nucleotide identity analysis demonstrated that TR1180 is a member of D. tsuruhatensis. TR1180 exhibited resistance to ß-lactam, aminoglycoside, tetracycline and sulphonamide antibiotics, but was susceptible to phenicols, fluoroquinolones and macrolides. Its genome is a single, circular chromosome measuring 6,711,018 bp in size. Whole-genome analysis identified 17 antibiotic resistance-related genes, which match the antimicrobial susceptibility profile of this strain, as well as 24 potential virulence factors and a number of metal resistance genes. Our data showed that Delftia possessed an open pan-genome and the genes in the core genome contributed to the pathogenicity and resistance of Delftia strains. Comparative genomics analysis of TR1180 with other publicly available genomes of Delftia showed diverse genomic features among these strains. D. tsuruhatensis TR1180 harbored a unique 38-kb genomic island flanked by a pair of 29-bp direct repeats with the insertion of a novel In4-like integron containing most of the specific antibiotic resistance genes within the genome. This study reports the findings of a fully sequenced genome from clinical D. tsuruhatensis, which provide researchers and clinicians with valuable insights into this uncommon species.

Characterization and identification of SFDC-1, a novel AmpC-type ß-lactamase in Serratia fonticola.

The clinical and environmental infections caused by AmpC ß-lactamases have been increasingly reported recently. In this study, we characterize the novel chromosome-encoded AmpC ß-lactamase SFDC-1 identified in Serratia fonticola strain R28, which was isolated from a rabbit raised on a farm in southern China. SFDC-1 shared the highest amino acid identity of 79.6% with the functionally characterized AmpC ß-lactamase gene blaYRC-1 , although it had highly homologous functionally uncharacterized relatives in the same species from different sources, including some of the clinical significance. The cloned blaSFDC-1 exhibited resistance to a broad spectrum of ß-lactam antibiotics, including most cephalosporins with the highest resistance to ampicillin, cefazolin and ceftazidime, with increased MIC levels ≥128-fold compared with the control strains. The purified SFDC-1 showed catalytic activities against ß-lactams with the highest catalytic activity to cefazolin. The genetic context of blaSFDC-1 and its relatives was conserved in the chromosome, and no mobile genetic elements were found surrounding them.

Identification and characteristics of a novel aminoglycoside phosphotransferase, APH(3')-IId, from an MDR clinical isolate of Brucella intermedia.

OBJECTIVES: To describe a novel chromosomal aminoglycoside phosphotransferase named APH(3')-IId identified in an MDR Brucella intermedia ZJ499 isolate from a cancer patient. METHODS: Species identity was determined by PCR and MALDI-TOF MS analysis. WGS was performed to determine the genetic elements conferring antimicrobial resistance. Gene cloning, transcriptional analysis and targeted gene deletion, as well as protein purification and kinetic analysis, were performed to investigate the mechanism of resistance. RESULTS: APH(3')-IId consists of 266 amino acids and shares the highest identity (48.25%) with the previously known APH(3')-IIb. Expression of aph(3')-IId in Escherichia coli decreased susceptibility to kanamycin, neomycin, paromomycin and ribostamycin. The aph(3')-IId gene in ZJ499 was transcriptionally active under laboratory conditions and the relative abundance of this transcript was unaffected by treatment with the above four antibiotics. However, deletion of aph(3')-IId in ZJ499 results in decreased MICs of these drugs. The purified APH(3')-IId showed phosphotransferase activity against kanamycin, neomycin, paromomycin and ribostamycin, with catalytic efficiencies (kcat/Km) ranging from ∼105 to 107 M-1 s-1. Genetic environment and comparative genomic analyses suggested that aph(3')-IId is probably a ubiquitous gene in Brucella, with no mobile genetic elements detected in its surrounding region. CONCLUSIONS: APH(3')-IId is a novel chromosomal aminoglycoside phosphotransferase and plays an important role in the resistance of B. intermedia ZJ499 to kanamycin, neomycin, paromomycin and ribostamycin. To the best of our knowledge, APH(3')-IId represents the fourth characterized example of an APH(3')-II enzyme.

Molecular and Functional Characterization of a Novel Plasmid-Borne bla NDM-Like Gene, bla AFM-1, in a Clinical Strain of Aeromonas hydrophila.

PURPOSE: An increasing frequency of antibiotic resistance has been observed in both clinical and environmental Aeromonas hydrophila isolates in recent years. However, there are still very few in-depth studies regarding the role of plasmids in the antibiotic resistance of A. hydrophila. Hence, we investigated the molecular and functional characterization of a multidrug-resistant plasmid encoding an NDM-like metallo-ß-lactamase, AFM-1, in the clinical A. hydrophila isolate SS332. METHODS: The minimum inhibitory concentrations (MICs) of 24 antibiotics against A. hydrophila SS332 were measured by the agar dilution method. The genome of A. hydrophila SS332 was sequenced with PacBio and Illumina platforms. Six plasmid-borne antimicrobial resistance genes were chosen for cloning, including bla AFM-1, bla OXA-1, msr(E), mph(E), aac(6')-Ib10, and aph(3')-Ia. Phylogenetic analysis, amino acid sequence alignment, and comparative genomic analysis were performed to elucidate the active site requirements and genetic context of the bla AFM-1 gene. RESULTS: A. hydrophila SS332 showed high levels of resistance to 15 antibiotics, especially those with MIC levels at or above 1024 µg/mL, including ampicillin, cefazolin, ceftriaxone, aztreonam, spectinomycin, and roxithromycin. Six plasmid-borne resistance genes from A. hydrophila were verified to be functional in E. coli DH5α. AFM-1 shared 86% amino acid identity with NDM-1 and showed resistance to ampicillin, cefazolin, cefoxitin, and ceftazidime. In addition, the bla AFM-1 gene was associated with three different novel ISCR19-like elements, designated ISCR19-1, ISCR19-2 and ∆ISCR19-3, which may be involved in the acquisition and mobilization of the bla AFM-1 gene. CONCLUSION: Our investigation showed that plasmid-borne resistance genes can contribute to antibiotic resistance in A. hydrophila SS332. A novel bla NDM-like gene, bla AFM-1, was verified to be functional and associated with novel ISCR19-like elements. This fact indicated the risk of spread of bla AFM-1 genes and ISCR19-like elements.

Characterization of florfenicol resistance genes in the coagulase-negative Staphylococcus (CoNS) isolates and genomic features of a multidrug-resistant Staphylococcus lentus strain H29.

BACKGROUND: With the wide use of florfenicol to prevent and treat the bacterial infection of domestic animals, the emergence of the florfenicol resistance bacteria is increasingly serious. It is very important to elucidate the molecular mechanism of the bacteria's resistance to florfenicol. METHODS: The minimum inhibitory concentration (MIC) levels were determined by the agar dilution method, and polymerase chain reaction was conducted to analyze the distribution of florfenicol resistance genes in 39 CoNS strains isolated from poultry and livestock animals and seafood. The whole genome sequence of one multidrug resistant strain, Staphylococcus lentus H29, was characterized, and comparative genomics analysis of the resistance gene-related sequences was also performed. RESULTS: As a result, the isolates from the animals showed a higher resistance rate (23/28, 82.1%) and much higher MIC levels to florfenicol than those from seafood. Twenty-seven animal isolates carried 37 florfenicol resistance genes (including 26 fexA, 6 cfr and 5 fexB genes) with one carrying a cfr gene, 16 each harboring a fexA gene, 5 with both a fexA gene and a fexB gene and the other 5 with both a fexA gene and a cfr gene. On the other hand, all 11 isolates from seafood were sensitive to florfenicol, and only 3 carried a fexA gene each. The whole genome sequence of S. lentus H29 was composed of a chromosome and two plasmids (pH29-46, pH29-26) and harbored 11 resistance genes, including 6 genes [cfr, fexA, ant(6)-Ia, aacA-aphD, mecA and mph(C)] encoded on the chromosome, 4 genes [cfr, fexA, aacA-aphD and tcaA] on pH29-46 and 1 gene (fosD) on pH29-26. We found that the S. lentus H29 genome carried two identical copies of the gene arrays of radC-tnpABC-hp-fexA (5671 bp) and IS256-cfr (2690 bp), of which one copy of the two gene arrays was encoded on plasmid pH29-46, while the other was encoded on the chromosome. CONCLUSIONS: The current study revealed the wide distribution of florfenicol resistance genes (cfr, fexA and fexB) in animal bacteria, and to the best of our knowledge, this is the first report that one S. lentus strain carried two identical copies of florfenicol resistance-related gene arrays.

Characterization of an IncR Plasmid with Two Copies of ISCR-Linked qnrB6 from ST968 Klebsiella pneumoniae.

To characterize the molecular structure of IncR plasmid-related sequences, comparative genomic analysis was conducted using 261 IncR plasmid backbone-related sequences. Among the sequences, 257 were IncR plasmids including the multidrug-resistance IncR plasmid pR50-74 from Klebsiella pneumoniae strain R50 of this work, and the other four were from bacterial chromosomes. The IncR plasmids were derived from different bacterial genera or species, mainly Klebsiella pneumoniae (70.82%, 182/257), Escherichia coli (11.28%, 29/257), Enterobacter cloacae (7.00%, 18/257), and Citrobacter freundii (3.50%, 9/257). The bacterial chromosomes carrying IncR plasmid backbone sequences were derived from Proteus mirabilis AOUC-001 and Klebsiella pneumoniae KPN1344, among others. The IncR backbone sequence of P. mirabilis AOUC-001 chromosome shows the highest identity with that of pR50-74. Complex class 1 integrons carrying various copies of ISCR1-sdr-qnrB6-△qacE/sul1 (ISCR1-linked qnrB6 unit) were identified in IncR plasmids. In addition to two consecutive copies of qnrB6-qacE-sul1, the other resistance genes encoded on pR50-74 are all related to mobile genetic elements, such as IS1006, IS26, and the class 1 integron. This study provides a clear understanding of the mobility and plasticity of the IncR plasmid backbone sequence and emphasizes the important role of ISCR in the recruitment of multicopy resistance genes.

Characterization of a Novel Chromosomal Class C ß-Lactamase, YOC-1, and Comparative Genomics Analysis of a Multidrug Resistance Plasmid in Yokenella regensburgei W13.

Yokenella regensburgei, a member of the family Enterobacteriaceae, is usually isolated from environmental samples and generally resistant to early generations of cephalosporins. To characterize the resistance mechanism of Y. regensburgei strain W13 isolated from the sewage of an animal farm, whole genome sequencing, comparative genomics analysis and molecular cloning were performed. The results showed that a novel chromosomally encoded class C ß-lactamase gene with the ability to confer resistance to ß-lactam antibiotics, designated bla YOC - 1, was identified in the genome of Y. regensburgei W13. Kinetic analysis revealed that the ß-lactamase YOC-1 has a broad spectrum of substrates, including penicillins, cefazolin, cefoxitin and cefotaxime. The two functionally characterized ß-lactamases with the highest amino acid identities to YOC-1 were CDA-1 (71.69%) and CMY-2 (70.65%). The genetic context of the bla YOC - 1 -ampR-encoding region was unique compared with the sequences in the NCBI nucleotide database. The plasmid pRYW13-125 of Y. regensburgei W13 harbored 11 resistance genes (bla OXA - 10, bla LAP - 2, dfrA14, tetA, tetR, cmlA5, floR, sul2, ant(3″)-IIa, arr-2 and qnrS1) within an ∼34 kb multidrug resistance region; these genes were all related to mobile genetic elements. The multidrug resistance region of pYRW13-125 shared the highest identities with those of two plasmids from clinical Klebsiella pneumoniae isolates, indicating the possibility of horizontal transfer of these resistance genes between bacteria of various origins.

Analysis of Resistance to Florfenicol and the Related Mechanism of Dissemination in Different Animal-Derived Bacteria.

Bacterial resistance to antibiotics has become an important concern for public health. This study was aimed to investigate the characteristics and the distribution of the florfenicol-related resistance genes in bacteria isolated from four farms. A total of 106 florfenicol-resistant Gram-negative bacilli were examined for florfenicol-related resistance genes, and the positive isolates were further characterized. The antimicrobial sensitivity results showed that most of them (100, 94.33%) belonged to multidrug resistance Enterobacteriaceae. About 91.51% of the strains carried floR gene, while 4.72% carried cfr gene. According to the pulsed-field gel electrophoresis results, 34 Escherichia coli were subdivided into 22 profiles, the genetic similarity coefficient of which ranged from 80.3 to 98.0%. The multilocus sequence typing (MLST) results revealed 17 sequence types (STs), with ST10 being the most prevalent. The genome sequencing result showed that the Proteus vulgaris G32 genome consists of a 4.06-Mb chromosome, a 177,911-bp plasmid (pG32-177), and a 51,686-bp plasmid (pG32-51). A floR located in a drug-resistant region on the chromosome of P. vulgaris G32 was with IS91 family transposase, and the other floR gene on the plasmid pG32-177 was with an ISCR2 insertion sequence. The cfr gene was located on the pG32-51 flanked by IS26 element and TnpA26. This study suggested that the mobile genetic elements played an important role in the replication of resistance genes and the horizontal resistance gene transfer.

RamA, a transcriptional regulator conferring florfenicol resistance in Leclercia adecarboxylata R25.

Due to the inappropriate use of florfenicol in agricultural practice, florfenicol resistance has become increasingly serious. In this work, we studied the novel florfenicol resistance mechanism of an animal-derived Leclercia adecarboxylata strain R25 with high-level florfenicol resistance. A random genomic DNA library was constructed to screen the novel florfenicol resistance gene. Gene cloning, gene knockout, and complementation combined with the minimum inhibitory concentration (MIC) detection were conducted to determine the function of the resistance-related gene. Sequencing and bioinformatics methods were applied to analyze the structure of the resistance gene-related sequences. Finally, we obtained a regulatory gene of an RND (resistance-nodulation-cell division) system, ramA, that confers resistance to florfenicol and other antibiotics. The ramA-deleted variant (LA-R25ΔramA) decreased the level of resistance against florfenicol and several other antibiotics, while a ramA-complemented strain (pUCP24-prom-ramA/LA-R25ΔramA) restored the drug resistance. The whole-genome sequencing revealed that there were five RND efflux pump genes (mdtABC, acrAB, acrD, acrEF, and acrAB-like) encoded over the chromosome, and ramA located upstream of the acrAB-like genes. The results of this work suggest that ramA confers resistance to florfenicol and other structurally unrelated antibiotics, presumably by regulating the RND efflux pump genes in L. adecarboxylata R25.

High-Temperature Deformation Behavior and Microstructural Characterization of Ti-35421 Titanium Alloy.

A self-designed Ti-35421 (Ti-3Al-5Mo-4Cr-2Zr-1Fe wt%) titanium alloy is a new type of low-cost high strength titanium alloy. In order to understand the hot deformation behavior of Ti-35421 alloy, isothermal compression tests were carried out under a deformation temperature range of 750-930 °C with a strain rate range of 0.01-10 s-1 in this study. Electron backscatter diffraction (EBSD) was used to characterize the microstructure prior to and post hot deformation. The results show that the stress-strain curves have obvious yielding behavior at a high strain rate (>0.1 s-1). As the deformation temperature increases and the strain rate decreases, the α phase content gradually decreases in the α + ß phase region. Meanwhile, spheroidization and precipitation of α phase are prone to occur in the α + ß phase region. From the EBSD analysis, the volume fraction of recrystallized grains was very low, so dynamic recovery (DRV) is the dominant deformation mechanism of Ti-35421 alloy. In addition to DRV, Ti-35421 alloy is more likely to occur in continuous dynamic recrystallization (CDRX) than discontinuous dynamic recrystallization (DDRX).

Determining the Genetic Characteristics of Resistance and Virulence of the "Epidermidis Cluster Group" Through Pan-Genome Analysis.

Staphylococcus caprae, Staphylococcus capitis, and Staphylococcus epidermidis belong to the "Epidermidis Cluster Group" (ECG) and are generally opportunistic pathogens. In this work, whole genome sequencing, molecular cloning and pan-genome analysis were performed to investigate the genetic characteristics of the resistance, virulence and genome structures of 69 ECG strains, including a clinical isolate (S. caprae SY333) obtained in this work. Two resistance genes (blaZ and aadD2) encoded on the plasmids pSY333-41 and pSY333-45 of S. caprae SY333 were confirmed to be functional. The bla region in ECG exhibited three distinct structures, and these chromosome- and plasmid-encoded bla operons seemed to follow two different evolutionary paths. Pan-genome analysis revealed their pan-genomes tend to be "open." For the virulence-related factors, the genes involved in primary attachment were observed almost exclusively in S. epidermidis, while the genes associated with intercellular aggregation were observed more frequently in S. caprae and S. capitis. The type VII secretion system was present in all strains of S. caprae and some of S. epidermidis but not in S. capitis. Moreover, the isd locus (iron regulated surface determinant) was first found to be encoded on the genomes of S. caprae and S. capitis. These findings suggested that the plasmid and chromosome encoded bla operons of ECG species underwent different evolution paths, as well as they differed in the abundance of virulence genes associated with adherence, invasion, secretion system and immune evasion. Identification of isd loci in S. caprae and S. capitis indicated their ability to acquire heme as nutrient iron during infection.

Prevalence and risk factors on age-related cataract and surgery in adults over 50 years old in Binhu District, Wuxi, China.

AIM: To investigate the prevalence and risk factors of age-related cataract (ARC), ARC surgery procedures, and postoperative vision results among adults over 50 years old in the Binhu District of Wuxi City, China. METHODS: Thirty basic sampling units were analyzed via a cluster random sampling method. Detailed medical histories were collected and eye examinations were performed. Cataract prevalence and surgical procedures were quantified. RESULTS: Among the 6150 participants, 1421 cataract cases were diagnosed and prevalence was 23.1%. The prevalence of cortical, nuclear, and posterior subcapsular cataracts increased with age (P<0.001). Cataract prevalence was significantly higher among elderly, female, or illiterate individuals and people with hypertension, diabetes, and a history of smoking and drinking (all P<0.05). As participant age increased and education level decreased, the frequency of cataract blindness surgeries gradually decreased, but without statistical significance within groups (P>0.05). The odds ratio of cataract patients who had or did not have cataract surgery was 3.15 (87/28) and the frequency of cataract blindness surgery was 75.7% (87/115). Poor visual outcomes was in 107 eyes (40.7%) after cataract surgery. Poor vision was mostly caused by uncorrected reflective errors (30.9%) and ocular comorbidities (41.1%). The prevalence of cataract surgery complications was 5.7% (15/263). Surgical complications and posterior capsular opacification were avoidable factors facilitating poor vision. CONCLUSION: ARC, especially in females and illiterate individuals, presents a public health problem in this district. Poor visual outcomes after cataract surgery are frequent. High-quality cataract surgeries and treatment of ocular comorbidities are vital.

Characterization of Two Macrolide Resistance-Related Genes in Multidrug-Resistant Pseudomonas aeruginosa Isolates.

In analyzing the drug resistance phenotype and mechanism of resistance to macrolide antibiotics of clinical Pseudomonas aeruginosa isolates, the agar dilution method was used to determine the minimum inhibitory concentrations (MICs), and PCR (polymerase chain reaction) was applied to screen for macrolide antibiotics resistance genes. The macrolide antibiotics resistance genes were cloned, and their functions were identified. Of the 13 antibiotics tested, P. aeruginosa strains showed high resistance rates (ranging from 69.5-82.1%), and MIC levels (MIC90 > 256 µg/ml) to macrolide antibiotics. Of the 131 known macrolide resistance genes, only two genes, mphE and msrE, were identified in 262 clinical P. aeruginosa isolates. Four strains (1.53%, 4/262) carried both the msrE and mphE genes, and an additional three strains (1.15%, 3/262) harbored the mphE gene alone. The cloned msrE and mphE genes conferred higher resistance levels to three second-generation macrolides compared to two first-generation ones. Analysis of MsrE and MphE protein polymorphisms revealed that they are highly conserved, with only 1-3 amino acids differences between the proteins of the same type. It can be concluded that even though the strains showed high resistance levels to macrolides, known macrolide resistance genes are seldom present in clinical P. aeruginosa strains, demonstrating that a mechanism other than this warranted by the mphE and msrE genes may play a more critical role in the bacteria's resistance to macrolides.

OXA-830, a Novel Chromosomally Encoded Extended-Spectrum Class D ß-Lactamase in Aeromonas simiae.

The diversity of class D ß-lactamases mediating resistance to ß-lactams has been increasingly reported recently. In this study, a novel class D oxacillinase named OXA-830 was identified in a fully sequenced Aeromonas simiae strain, which was isolated from sewage discharged from a farm in southern China. OXA-830 shares the highest amino acid identity of 79.3% with an OXA-12-like variant named OXA-725. When expressed in E. coli DH5α, OXA-830 conferred resistance to penicillins and selected ß-lactamase inhibitors but not to cephalosporins and carbapenems. Kinetic analysis of OXA-830 revealed a broad substrate profile including penicillins, cefazolin, cefoxitin, and ceftazidime but not carbapenems. The hydrolytic activity was significantly inhibited by sulbactam, followed by tazobactam, but was less effectively inhibited by clavulanic acid. The bla OXA- 830 gene was located on the A. simiae A6 chromosome and the bla OXA- 830-related region was bracketed by a pair of perfect inverted repeats.

In Vitro Susceptibility and Florfenicol Resistance in Citrobacter Isolates and Whole-Genome Analysis of Multidrug-Resistant Citrobacter freundii.

The genus Citrobacter is an opportunistic pathogen causing infections in animals, and the published data for its resistance to florfenicol are scarce. In this study, we investigated the antimicrobial susceptibility and molecular characteristics of florfenicol resistance genes among Citrobacter isolates from animal and relevant environmental samples and conducted a comparative analysis of a multidrug-resistant Citrobacter freundii strain isolated from a rabbit. Among 20 Citrobacter strains isolated from animal samples, resistance was most commonly observed to ampicillin (100%), tetracycline (75%), streptomycin (65%), florfenicol (60%), chloramphenicol (60%), and aztreonam (50%), while all the strains found in environmental samples were resistant to few antibiotics. The florfenicol resistance gene floR was detected in 12 isolates (48%, 12/25) from animal samples, and all of the floR-positive isolates were resistant to florfenicol with minimum inhibitory concentration (MIC) values ≥256 µg/mL. Sequencing and comparative analysis of the plasmids from a multidrug-resistant C. freundii isolate named R47 showed that the floR-containing region in the plasmid pR47-54 was a truncated transposon-like structure and could be found on both plasmids and chromosomes of bacteria of either animal or human origin. Furthermore, a range of antimicrobial and metal resistance genes associated with mobile genetic elements could be identified in pR47-54 and the other plasmid pR47-309 of C. freundii R47. These results provide in-depth views into the phenotypic and molecular characteristics of Citrobacter isolates recovered from animal and relevant environmental samples, as well as highlight the role horizontal gene transfer plays in the dissemination of plasmid-encoded resistance genes.

Clinical Efficacy of Ciliary Ring Incision Combined with Modified Partial Pars Plana Vitrectomy for Malignant Glaucoma.

BACKGROUND Currently, safe and effective surgical treatment of malignant glaucoma is still under investigation. This study evaluated the clinical efficacy of ciliary ring incision combined with modified partial pars plana vitrectomy in the treatment of malignant glaucoma. The technique is particularly useful in the treatment of "phakic" patients with malignant glaucoma, especially those who wish to preserve the natural lens. MATERIAL AND METHODS We retrospectively analyzed 13 cases (16 eyes) of malignant glaucoma in which patients underwent ciliary ring incision combined with modified partial pars plana vitrectomy based on follow-up data collected from May 2004 to March 2017. The data we analyzed included postoperative best-corrected visual acuity(BCVA), intraocular pressure (IOP), anterior chamber depth (ACD), optic cup changes, and surgical complications; some patients underwent visual field tracking. The mean follow-up period was 33.1±10.6 (range, 19-46) months. RESULTS A statistically significant number of eyes had improved visual acuity 1 year after surgery compared with the preoperative difference (Z=-3.853, P=0.000). Increases in the mean anterior chamber depth and decreases in the mean IOP measured at the 1-week and the 1-year follow-ups were also statistically significant. There were no serious complications during the follow-up period. CONCLUSIONS Ciliary ring incision combined with modified partial pars plana vitrectomy for malignant glaucoma not only provided a clear and reliable intraoperative vitrectomy channel, but it also caused less disturbance of intraocular tissue structure and fewer complications. It also has the advantage of preserving the lens and avoiding further damage to the anatomy in the anterior segment of the eye.

Prevalence and Causes of Visual Impairment in Adults in Binhu District, Wuxi, China.

BACKGROUND Previously reported data has guided the treatment and prevention of blindness. This study aimed to evaluate the current prevalence and causes of visual impairment among adults who were 50 years old and older in the Binhu District of Wuxi City, China. MATERIAL AND METHODS A randomized sample of stratified clusters was used to analyze individuals from 30 basic sampling units in Wuxi Binhu District. Visual impairment was defined according to World Health Organization (WHO) standards. RESULTS A total of 6725 people who were at least 50 years old participated in this study. According to WHO standards, bilateral low vision and blindness prevalence were both higher in women than in men (low vision: 6.5% vs. 5.2%; and blindness: 1.4% vs. 0.8%; P=0.022 and P=0.039, respectively). The incidence of bilateral visual impairment increased significantly with age (P<0.001 and P<0.001, respectively). Further studies showed that the main causes of bilateral low vision were cataract, high myopic macular degeneration (MMD), and age-related macular degeneration (AMD). The main causes of bilateral blindness were cataract, MMD, and eye loss/atrophy, while the main causes of monocular low vision were cataract, MD, and AMD. The main causes of monocular blindness were cataract, eye loss/atrophy, and AMD. CONCLUSIONS The prevalence of low vision and blindness remains high in the Binhu District of Wuxi City in China, especially among older women. In our study, cataracts were the leading cause of visual impairment. Our study highlights that some efforts should be initiated to prevent and treat blindness and low vision. Additional causes of visual impairment were MMD, AMD, and eye loss/atrophy.