Prevalence and Molecular Characterization of Shiga Toxin-Producing Escherichia coli from Food and Clinical Samples.

Shiga toxin-producing Escherichia coli (STEC) is one of the most prominent food-borne pathogens in humans. The current study aims to detect and to analyze the virulence factors, antibiotic resistance, and plasmid profiles for forty-six STEC strains, isolated from clinical and food strains. Pulsed-field gel electrophoresis (PFGE) was used to determine the genetic relatedness between different serotypes and sources of samples. The clinical samples were found to be resistant to Nb (100%), Tet (100%), Amp (20%), SXT (15%), and Kan (15%) antibiotics. In contrast, the food strains were found to be resistant to Nb (100%), Tet (33%), Amp (16.6%), and SXT (16.6%) antibiotics. The PFGE typing of the forty-six isolates was grouped into more than ten clusters, each with a similarity between 30% and 70%. Most of the isolates were found positive for more than five virulence genes (eae, hlyA, stx1, stx2, stx2f, stx2c, stx2e, stx2, nelB, pagC, sen, toxB, irp, efa, and efa1). All the isolates carried different sizes of the plasmids. The isolates were analyzed for plasmid replicon type by PCR, and 72.5% of the clinical isolates were found to contain X replicon-type plasmid, 50% of the clinical isolates contained FIB replicon-type plasmid, and 17.5% of the clinical isolates contained Y replicon-type plasmid. Three clinical isolates contained both I1 and Hi1 replicon-type plasmid. Only two food isolates contained B/O and W replicon-type plasmid. These results indicate that STEC strains have diverse clonal populations among food and clinical strains that are resistant to several antimicrobials. In conclusion, our findings indicate that food isolates of STEC strains harbor virulence, antimicrobial resistance, plasmid replicon typing determinants like those of other STEC strains from clinical strains. These results suggest that these strains are unique and may contribute to the virulence of the isolates. Therefore, surveillance and characterization of STEC strains can provide useful information about the prevalence of STEC in food and clinical sources. Furthermore, it will help to identify STEC serotypes that are highly pathogenic to humans and may emerge as a threat to public health.

Draft genome sequences of nine non-O157 Shiga toxin-producing Escherichia coli in ready-to-eat food from supermarkets in Argentina.

Non-O157 Shiga toxin-producing Escherichia coli (STEC) are recognized as an important group of bacterial enteropathogens. Here, we report the draft genome sequence of nine strains of non-O157 STEC isolated from ready-to-eat foods in Argentina. The whole-genome sequence data provide a better understanding of these isolates and will aid epidemiological investigation during outbreaks.

Draft Genome Sequences of 14 Fluoroquinolone-Resistant Escherichia coli Isolates from Imported Shrimp.

We report the draft genome sequences of 14 fluoroquinolone-resistant Escherichia coli strains that were isolated from imported shrimp. All isolates contained multiple point mutations in the quinolone resistance-determining regions (QRDRs) and non-QRDRs of gyrA, parC, and parE genes. The data improve the understanding of fluoroquinolone resistance and indicate resistance mechanisms.

Draft Genome Sequences of Tetracycline-Resistant Shiga Toxin-Producing Escherichia coli Isolates from Food.

Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen transmitted from animal to humans through contaminated food. Here, we report the draft genome sequences of six STEC isolates (six serotypes) from food (cheese, coriander, and pea protein pellets) in different countries; these isolates were resistant to tetracycline, with MIC values ranging from <1.5 to 256 µg/mL.

Draft Genome Sequences of Sixteen Fluoroquinolone-Resistant Extraintestinal Escherichia coli Isolates from Human Patients.

We report here the draft genome sequences of 16 fluoroquinolone-resistant extraintestinal Escherichia coli isolates from human patients. These isolates had high MICs (32 to 256 µg/mL) for ciprofloxacin and contained point mutations in the quinolone resistance-determining region (QRDR) of both gyrA and parC that confer resistance to fluoroquinolone. The whole-genome sequence data provide a better understanding of the fluoroquinolone resistance mechanisms in these isolates and would be beneficial in source tracking these pathogens during pandemic outbreaks.

Enhancing the antibacterial efficacy of aluminum foil by nanostructuring its surface using hot water treatment.

Bacterial biofilm has become one of the most frequent health problems as it contributes to persistent chronic infections. Therefore, it is vital to find alternatives to currently used bactericidal agents to prevent bacterial contamination on surfaces effectively and prevent the biofilms formation. Several metallic materials are well known for their antimicrobial activity; this includes copper, copper alloys, silver, gold, titanium, and zinc. On the other hand, some metals, such as aluminum, do not have noteworthy antimicrobial properties. In this study, we demonstrate that the antibacterial activity of household aluminum foil can be enhanced by nanostructuring the foil's surface by a simple hot water treatment (HWT) process. Cultures ofEscherichia coliandStaphylococcus aureuswere grown on nutrient agar while exposed to the samples of treated and untreated Al foils and left for 24 h. Our results indicate that treated Al foil can more effectively inhibit the bacteria growth compared to the regular untreated Al foil. This enhancement in antibacterial property might be due to a combination of chemical and morphological changes that the cell undergoes once it encounters nanofeatures of HWT-Al foil surface.

Antimicrobial resistance and related gene analysis of Salmonella from egg and chicken sources by whole-genome sequencing.

Whole-genome sequencing (WGS) is a valuable tool in research on foodborne pathogens. In this study, a total of 143 isolates of Salmonella serotypes Enteritidis, Typhimurium, and Heidelberg sourced from eggs and chickens were analyzed for their antimicrobial resistance profiles using WGS data. The isolates carried high rate of genes resistant to aminoglycoside (70.63%), tetracycline (26.57%), fosfomycin (25.17%), sulfonamides (23.78%), and ß-lactamases (15.38%); and aadA was the most frequently observed antimicrobial resistance gene (ARG). Antimicrobial resistance varies by Salmonella serotypes, with Salmonella enterica serovar Enteritidis (Salmonella ser. Enteritidis) isolates being highly resistant to aminoglycoside (particularly streptomycin); Salmonella ser. Typhimurium more resistant to aminoglycoside, tetracycline, and sulfonamides; and Salmonella ser. Heidelberg more resistant to aminoglycoside and fosfomycin. Salmonella ser. Typhimurium isolates presented more varieties of ARG than Salmonella ser. Enteritidis and Salmonella ser. Heidelberg. Our data showed that 5 isolates of Salmonella ser. Typhimurium and Salmonella ser. Heidelberg contained ARG resistant to ≥ 5 antimicrobials. In addition, 23 Salmonella isolates carried ARG resistant to 4 antimicrobials.

Accuracy of biometric formulae in hypermetropic patients undergoing cataract surgery.

PURPOSE: To audit and analyse the accuracy of current biometric formulae on refractive outcomes following cataract surgery in patients with axial length less than 22 mm. METHODS: A total of 84 eyes from 84 patients with axial length <22 mm were identified from consecutive patients undergoing cataract surgery retrospectively at a single university hospital. All subjects had biometry using the IOLMaster (Carl Zeiss Meditec, Inc, Dublin, CA, USA) and a Sensar AR40 intraocular lens implant (Abbott Medical Optics, CA, USA). One eye from each patient was randomly selected for inclusion. Prediction errors were calculated by comparing expected refraction from optimized formulas (SRK/T, Hoffer Q, Haigis and Holladay 1) to postoperative refraction. A national survey of ophthalmologists was conducted to ascertain biometric formula preference for small eyes. RESULTS: The mean axial length was 21.00 ± 0.55 mm. Mean error was greatest for Hoffer Q at -0.57 dioptres. There was no significant difference in mean absolute error between formulae. SRK/T achieved the highest percentage of outcomes within 0.5 dioptres (45.2%) and 1 dioptre (76.2%) of target. Shallower anterior chamber depth was associated with higher mean absolute error for SRK/T (p = 0.028), Hoffer Q (p = 0.003) and Haigis (p = 0.016) but not Holladay (p = 0.111). CONCLUSION: SRK/T had the highest proportion of patients achieving refractive results close to predicted outcomes. However, there was a significant association between a shallower anterior chamber depth and higher mean absolute error for all formulae except Holladay 1. This suggests that anterior chamber depth with axial length should be considered when counselling patients about refractive outcome.

Intravitreal Dexamethasone Implant (Ozurdex) to Control Recurrent Severe Idiopathic Uveitis Leads to Improvement in Steroid-Induced Diabetes Mellitus.

Steroid-induced diabetes mellitus (SIDM) poses a unique challenge for the physician and ophthalmologist when faced with chronic recurrent uveitis controlled only with systemic steroids. We report a unique case where SIDM improved significantly following administration of intravitreal dexamethasone. A 53-year-old female had a history of recurrent idiopathic anterior uveitis that required oral steroids for control despite orbital floor steroids and systemic immunosuppression. After 9 years of oral steroid treatment she was diagnosed with SIDM necessitating insulin therapy. Following intravitreal dexamethasone implant, her oral steroid use was tapered with subsequent improvement in her diabetes and eventual cessation of insulin. In uveitis, steroid sparing immunosuppression may be used to minimize systemic steroid exposure. In this case, we demonstrated that an intravitreal dexamethasone implant achieved this goal. We recommend considering the use of such implants in patients with recurrent uveitis, particularly when there are significant steroid-induced side effects.

Draft Genome Sequences of Ciprofloxacin-Resistant Salmonella enterica Strains with Multiple-Antibiotic Resistance, Isolated from Imported Foods.

We report here the draft genome sequences of 15 ciprofloxacin-resistant Salmonella enterica strains with resistance to multiple other antibiotics, including aminoglycosides, ß-lactams, sulfonamides, tetracycline, and trimethoprim, isolated from different imported foods. Three strains (NCTR75, NCTR281, and NCTR350) showed a high level of ciprofloxacin resistance compared to that of the other isolates. The whole-genome sequencing data provide a better understanding of the antibiotic resistance mechanisms and virulence properties of these isolates.

Primary Transitional Cell Carcinoma of the Conjunctiva.

A 77-year-old male presented with a large papillomatous conjunctival lesion on his lower eyelid. Biopsy and extensive systemic investigation revealed this to be a primary conjunctival transitional cell carcinoma. Patient preference and coexisting medical problems dictated conservative management with surgical debulking, topical mitomicin, and radiotherapy. Local control has been maintained for 4 years to date.

Isolation and Characterization of Antimicrobial-Resistant Nontyphoidal Salmonella enterica Serovars from Imported Food Products.

The objective of this study was to determine antimicrobial resistance and elucidate the resistance mechanism in nontyphoidal Salmonella enterica serovars isolated from food products imported into the United States from 2011 to 2013. Food products contaminated with antimicrobial-resistant nontyphoidal S. enterica were mainly imported from Taiwan, Indonesia, Vietnam, and China. PCR, DNA sequencing, and plasmid analyses were used to characterize antimicrobial resistance determinants. Twentythree of 110 S. enterica isolates were resistant to various antimicrobial classes, including ß-lactam, aminoglycoside, phenicol, glycopeptide, sulfonamide, trimethoprim, and/or fluoroquinolone antimicrobial agents. Twelve of the isolates were multidrug resistant strains. Antimicrobial resistance determinants blaTEM-1, blaCTX-M-9, blaOXA-1, tetA, tetB, tetD, dfrA1, dfrV, dhfrI, dhfrXII, drf17, aadA1, aadA2, aadA5, orfC, qnrS, and mutations of gyrA and parC were detected in one or more antimicrobial-resistant nontyphoidal S. enterica strains. Plasmid profiles revealed that 12 of the 23 antimicrobial-resistant strains harbored plasmids with incompatibility groups IncFIB, IncHI1, IncI1, IncN, IncW, and IncX. Epidemiologic and antimicrobial resistance monitoring data combined with molecular characterization of antimicrobial resistance determinants in Salmonella strains isolated from imported food products may provide information that can be used to establish or implement food safety programs to improve public health.

Characterization of extended-spectrum ß-lactamase (ESBL) producing non-typhoidal Salmonella (NTS) from imported food products.

Food contaminated with extended-spectrum ß-lactamase (ESBL)-producing Salmonella enterica has emerged as an important global issue due to the international food-product trade. Therefore, the purpose of this study was to investigate whether imported food products can serve as a reservoir for non-typhoidal Salmonella (NTS) that can transmit ß-lactam-resistance to humans through ingestion of the contaminated food. NTS isolates (n=110) were collected from various imported food products (n=3480) from 2011 to 2013. The NTS isolates were analyzed by serotyping, antimicrobial susceptibility tests, and plasmid profiling. Salmonella ser. Weltevreden, Salmonella ser. Newport, Salmonella ser. Senftenberg, Salmonella ser. Virchow, Salmonella ser. Enteritidis, Salmonella ser. Typhimurium, and Salmonella ser. Bareilly were the most prevalent serovars. Nine NTS strains were resistant to ampicillin and/or one or more cephalosporins (MIC>32 µg/mL). Polymerase chain reaction (PCR) detection revealed that all nine isolates carried the bla(TEM-1) ß-lactamase gene, with or without the bla(CTX-M-9) or bla(OXA-1) genes. Two isolates, PSS_913 and PSS_988, exhibited decreased susceptibility to extended-spectrum cephalosporins and ampicillin. Plasmids ranging in size from less than 8 to over 165 kbp, from all of the 9 resistant isolates, belonged to the IncHI1, IncI1, IncN, or IncX groups. Conjugation experiments and Southern hybridization, using bla(TEM-1), confirmed the plasmid-mediated transfer of ESBL genes, which resulted in increased MICs of ß-lactams for Escherichia coli transconjugants. The contamination of imported food products by NTS with conjugative plasmid-borne ESBL genes may contribute to the spread of ESBL-producing NTS and compromise the therapeutic activity of extended-spectrum ß-lactam antibiotics.

Detection and functionality of the CdtB, PltA, and PltB from Salmonella enterica serovar Javiana.

Salmonella infection is one of the major foodborne illnesses in the United States. Several Gram-negative bacterial pathogens, including Salmonella Typhi, produce cytolethal distending toxin (CDT), which arrests growth, induces apoptosis of infected host cells and extends persistence of pathogenic bacteria in the host. The aim of this study was to characterize the functionality of CDT (cdtB, pltA and pltB) from nontyphoidal Salmonella isolates. Fifty Salmonella enterica serovar Javiana isolates from food, environmental, and clinical samples were screened for cdtB, pltA, and pltB genes by PCR, and all were positive for all three genes. Nucleotide sequence analysis of all amplified PCR products showed 100% identity to S. Typhi cdtB. To understand the roles of CdtB, PltA, and PltB in S. Javiana, cdtB, pltA, and pltB deletion mutants were constructed using a lambda Red-based recombination system. In vitro-cultured HeLa cell lines were infected with a wild-type strain and its isogenic ∆cdtB, ∆pltA, and ∆pltB to determine whether the strains of S. Javiana are responsible for invasion and cytolethal distending intoxication, including cell cycle arrest, cytoplasmic distension, and nuclear enlargement of host target cells. The results showed that HeLa cells infected with S. Javiana wild type were arrested in G2 /M and had distended cytoplasm and nuclei that were larger than those infected with S. Javiana ∆cdtB and ∆pltA strains. The S. Javiana ∆pltB strain retained the ability to induce cytoplasmic distension and cell cycle arrest, whereas the complemented ∆cdtB and ∆pltA S. Javiana strains showed activity like the wild-type strains. CdtB and pltA from S. Javiana had apparent effects on the distension of both cytoplasm and nucleus as well as cell cycle arrest of HeLa cell lines after 72 h of infection. Our data show a significant difference between the wild-type cdtB strain and its isogenic ∆cdtB for invasion of the cell lines. Therefore, CdtB produced from S. Javiana strains may play an important role in pathogenesis in host cells.

Isolation and molecular characterization of Salmonella enterica serovar Enteritidis from poultry house and clinical samples during 2010.

A total of 60 Salmonella enterica serovar (ser.) Enteritidis isolates, 28 from poultry houses and 32 from clinical samples, were isolated during 2010. These isolates were subjected to testing and analyzed for antibiotic resistance, virulence genes, plasmids and plasmid replicon types. To assess genetic diversity, pulsed-field gel electrophoresis (PFGE) fingerprinting, using the XbaI restriction enzyme, Multiple-Locus Variable-Number Tandem Repeat Analysis (MLVA) and plasmid profiles were performed. All isolates from poultry, and 10 out of 32 clinical isolates were sensitive to ampicillin, chloramphenicol, gentamicin, kanamycin, nalidixic acid, sulfisoxazole, streptomycin, and tetracycline. Twenty-one of thirty-two clinical isolates were resistant to ampicillin and tetracycline, and one isolate was resistant to nalidixic acid. PFGE typing of sixty ser. Enteritidis isolates by XbaI resulted in 10-12 bands and grouped into six clusters each with similarity from 95% to 81%. The MLVA analysis of sixty isolates gave 18 allele profiles with the majority of isolates displayed in three groups, and two clinical isolates found to be new in the PulseNet national MLVA database. All isolates were positive for 12 or more of the 17 virulence genes mostly found in S. enterica (spvB, spiA, pagC, msgA, invA, sipB, prgH, spaN, orgA, tolC, iroN, sitC, IpfC, sifA, sopB, and pefA) and negative for one gene (cdtB). All isolates carried a typical 58 kb plasmid, type Inc/FIIA. Three poultry isolates and one clinical isolate carried small plasmids with 3.8, 6, 7.6 and 11.5 kb. Ten of the clinical isolates carried plasmids, with sizes 36 and 38 kb, types IncL/M and IncN, and one isolate carried an 81 kb plasmid, type IncI. Southern hybridization of a plasmid with an Inc/FIIA gene probe hybridized one large 58 kb plasmid in all isolates. Several large and small plasmids from poultry isolates were not typed by our PCR-based method. These results confirmed that PFGE fingerprinting has limited discriminatory power for ser. Enteritidis in both poultry and clinical sources. However, the plasmid and MLVA allele profiles were a useful and important epidemiology tool to discriminate outbreak strains of ser. Enteritidis from poultry and clinical samples.

The sub-species characterization and antimicrobial resistance of Listeria monocytogenes isolated from domestic and imported food products from 2004 to 2011.

Thirty-five Listeria monocytogenes strains isolated from domestic and imported food products including seafood, vegetables, and dairy foods were characterized by serotyping, molecular sub-typing, and antimicrobial susceptibility. L. monocytogenes serovars 1/2a and 1/2b strains were dominant as compared to other two serovars 4b and 1/2c strains. The dendrogram of AscI or ApaI-digested PFGE profiles of L. monocytogenes strains was classified into 23 (with 8 groups) or 3 (with 2 groups) different PFGE types, respectively. The AscI-digested groups consisted of the same serovar or food-source. Antimicrobials such as ampicillin, gentamicin, and trimethoprim-sulfamethoxazole are widely used in the treatment of listeriosis. Of the isolates used in this study, NCTR_LM14 and NCTR_LM57 were resistant to several classes of antimicrobials including aminoglycosides, penicillin, tetracycline, glycopeptide and fluoroquinolones. The multi-antimicrobial resistant isolates also showed higher efflux pump activity as compared to the antimicrobial sensitive strains NCTR_LM06 and L. monocytogenes EGD-e. This study demonstrates that L. monocytogenes isolates from various food products are genetically diverse with some isolates being resistant to more than 3 different antibiotic classes. This study also indicates that the efflux pump activity of the antibiotic resistant strains was higher than antimicrobial susceptible strains. Therefore, we propose that the antibiotic resistance observed in these strains may be conferred by the results of a highly active efflux pump system.

Risk stratifying retinal breaks.

OBJECTIVE: Argon laser retinopexy has been the primary treatment for retinal breaks for many decades. Prevention of progression to retinal detachment (RD) is the main objective. The benefit of laser retinopexy is well documented, although little has been reported on the risk factors for progression to RD. By addressing this issue, patients at high risk can be identified, and more timely specialist retinal input can be sought. METHODS: Data over a 6-month period from 45 consecutive patients undergoing laser retinopexy were reviewed. Patients were categorized into complete success (no more than 1 laser treatment), qualified success (no more than 3 laser or cryotherapy treatments), and treatment failure (more than 3 laser or cryotherapy treatments or progression to RD). RESULTS: Complete success was observed in 53.5% of patients, a further 34.9% of patients achieved a qualified success, and the remainder of the patients (11.6%) fell into the treatment failure category. About 9.3% of patients required cryotherapy, and 7.0% of patients underwent RD surgery. Patients with a bridging blood vessel and vitreous hemorrhage were significantly more likely to be in the treatment failure category than those without. RD was significantly associated with the presence of vitreous hemorrhage. CONCLUSIONS: Patients with retinal breaks associated with bridging blood vessels and vitreous hemorrhage are at greater risk for poorer outcome. The area of subretinal fluid was not linked to failure. If complete laser of a tear is not possible or if concerns remain regarding treatment efficacy, prompt referral to a retina specialist for further management is recommended.