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  • American Society for Microbiology  (13)
  • English  (13)
  • 1
    Online Resource
    Online Resource
    Effects of High-Pressure Treatment on Spores of Clostridium Species
    American Society for Microbiology ; 2016
    In:  Applied and Environmental Microbiology Vol. 82, No. 17 ( 2016-09), p. 5287-5297
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 82, No. 17 ( 2016-09), p. 5287-5297
    Abstract: This work analyzes the high-pressure (HP) germination of spores of the food-borne pathogen Clostridium perfringens (with inner membrane [IM] germinant receptors [GRs] ) and the opportunistic pathogen Clostridium difficile (with no IM GRs), which has growing implications as an emerging food safety threat. In contrast to those of spores of Bacillus species, mechanisms of HP germination of clostridial spores have not been well studied. HP treatments trigger Bacillus spore germination through spores' IM GRs at ∼150 MPa or through SpoVA channels for release of spores' dipicolinic acid (DPA) at ≥400 MPa, and DPA-less spores have lower wet heat resistance than dormant spores. We found that C. difficile spores exhibited no germination events upon 150-MPa treatment and were not heat sensitized. In contrast, 150-MPa-treated unactivated C. perfringens spores released DPA and became heat sensitive, although most spores did not complete germination by fully rehydrating the spore core, but this treatment of heat-activated spores led to almost complete germination and greater heat sensitization. Spores of both clostridial organisms released DPA during 550-MPa treatment, but C. difficile spores did not complete germination and remained heat resistant. Heat-activated 550-MPa-HP-treated C. perfringens spores germinated almost completely and became heat sensitive. However, unactivated 550-MPa-treated C. perfringens spores did not germinate completely and were less heat sensitive than spores that completed germination. Since C. difficile and C. perfringens spores use different mechanisms for sensing germinants, our results may allow refinement of HP methods for their inactivation in foods and other applications and may guide the development of commercially sterile low-acid foods. IMPORTANCE Spores of various clostridial organisms cause human disease, sometimes due to food contamination by spores. Because of these spores' resistance to normal decontamination regimens, there is continued interest in ways to kill spores without compromising food quality. High hydrostatic pressure (HP) under appropriate conditions can inactivate bacterial spores. With growing use of HP for food pasteurization, advancement of HP for commercial production of sterile low-acid foods requires understanding of mechanisms of spores' interactions with HP. While much is known about HP germination and inactivation of spores of Bacillus species, how HP germinates and inactivates clostridial spores is less well understood. In this work we have tried to remedy this information deficit by examining germination of spores of Clostridium difficile and Clostridium perfringens by several HP and temperature levels. The results may give insight that could facilitate more efficient methods for spore eradication in food sterilization or pasteurization, biodecontamination, and health care.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01363-16
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2016
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  • 2
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    Proximity to Other Commercial Turkey Farms Affects Colonization Onset, Genotypes, and Antimicrobial Resistance Profiles of Campylobacter spp. in Turkeys: Suggestive Evidence from a Paired-Farm Model
    American Society for Microbiology ; 2018
    In:  Applied and Environmental Microbiology Vol. 84, No. 18 ( 2018-09-15)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 84, No. 18 ( 2018-09-15)
    Abstract: Campylobacter is a leading foodborne pathogen, and poultry products are major vehicles for human disease. However, determinants impacting Campylobacter colonization in poultry remain poorly understood, especially with turkeys. Here, we used a paired-farm design to concurrently investigate Campylobacter colonization and strain types in two turkey breeds (Hybrid and Nicholas) at two farms in eastern North Carolina. One farm (the Teaching Animal Unit [TAU]) was a university teaching unit at least 40 km from commercial turkey farms, while the other (SIB) was a commercial farm in an area with a high density of turkey farms. Day-old birds were obtained from the same breeder flock and hatchery and placed at TAU and SIB on the same day. Birds were marked to identify turkey breed and then commingled on each farm. TAU birds became colonized 1 week later than SIB and had lower initial Campylobacter levels in the cecum. Interestingly, Campylobacter genotypes and antimicrobial resistance profiles differed markedly between the farms. Most TAU isolates were resistant only to tetracycline, whereas multidrug-resistant isolates predominated at SIB. Multilocus sequence typing revealed that no Campylobacter genotypes were shared between TAU and SIB. A bovine-associated genotype (sequence type 1068 [ST1068]) predominated in Campylobacter coli from TAU, while SIB isolates had genotypes commonly encountered in commercial turkey production in the region. One multidrug-resistant Campylobacter jejuni strain (ST1839) showed significant association with one of the two turkey breeds. The findings highlight the need to further characterize the impact of farm-specific factors and host genetics on antimicrobial resistance and genotypes of C. jejuni and C. coli that colonize turkeys. IMPORTANCE Colonization of poultry with Campylobacter at the farm level is complex, poorly understood, and critically linked to contamination of poultry products, which is known to constitute a leading risk factor for human campylobacteriosis. Here, we investigated the use of a paired-farm design under standard production conditions and in the absence of experimental inoculations to assess potential impacts of farm and host genetics on prevalence, antimicrobial resistance and genotypes of Campylobacter in commercial turkeys of two different breeds. Data suggest impacts of farm proximity to other commercial turkey farms on the onset of colonization, genotypes, and antimicrobial resistance profiles of Campylobacter colonizing the birds. Furthermore, the significant association of a specific multidrug-resistant Campylobacter jejuni strain with turkeys of one breed suggests colonization partnerships at the Campylobacter strain-turkey breed level. The study design avoids potential pitfalls associated with experimental inoculations, providing novel insights into the dynamics of turkey colonization with Campylobacter in actual farm ecosystems.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01212-18
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
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  • 3
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    Role of FKS Mutations in Candida glabrata: MIC Values, Echinocandin Resistance, and Multidrug Resistance
    American Society for Microbiology ; 2014
    In:  Antimicrobial Agents and Chemotherapy Vol. 58, No. 8 ( 2014-08), p. 4690-4696
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 58, No. 8 ( 2014-08), p. 4690-4696
    Abstract: Candida glabrata is the second leading cause of candidemia in U.S. hospitals. Current guidelines suggest that an echinocandin be used as the primary therapy for the treatment of C. glabrata disease due to the high rate of resistance to fluconazole. Recent case reports indicate that C. glabrata resistance to echinocandins may be increasing. We performed susceptibility testing on 1,380 isolates of C. glabrata collected between 2008 and 2013 from four U.S. cities, Atlanta, Baltimore, Knoxville, and Portland. Our analysis showed that 3.1%, 3.3%, and 3.6% of the isolates were resistant to anidulafungin, caspofungin, and micafungin, respectively. We screened 1,032 of these isolates, including all 77 that had either a resistant or intermediate MIC value with respect to at least one echinocandin, for mutations in the hot spot regions of FKS1 and FKS2 , the major mechanism of echinocandin resistance. Fifty-one isolates were identified with hot spot mutations, 16 in FKS1 and 35 in FKS2 . All of the isolates with an FKS mutation except one were resistant to at least one echinocandin by susceptibility testing. Of the isolates resistant to at least one echinocandin, 36% were also resistant to fluconazole. Echinocandin resistance among U.S. C. glabrata isolates is a concern, especially in light of the fact that one-third of those isolates may be multidrug resistant. Further monitoring of U.S. C. glabrata isolates for echinocandin resistance is warranted.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.03255-14
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2014
    detail.hit.zdb_id: 1496156-8
    detail.hit.zdb_id: 217602-6
    SSG: 12
    SSG: 15,3
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  • 4
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    Characterization of Methicillin-Resistant Staphylococcus aureus Isolates Collected in 2005 and 2006 from Patients with Invasive Disease: a Population-Based Analysis
    American Society for Microbiology ; 2009
    In:  Journal of Clinical Microbiology Vol. 47, No. 5 ( 2009-05), p. 1344-1351
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 47, No. 5 ( 2009-05), p. 1344-1351
    Abstract: This study characterizes 1,984 methicillin-resistant Staphylococcus aureus (MRSA) isolates collected in 2005 and 2006 from normally sterile sites in patients with invasive MRSA infection. These isolates represent a convenience sample of all invasive MRSA cases reported as part of the Active Bacterial Core surveillance system in eight states in the United States. The majority of isolates were from blood (83.8%), joints (4.1%), and bone (4.2%). Isolates were characterized by pulsed-field gel electrophoresis (PFGE); SCC mec typing; susceptibility to 15 antimicrobial agents; and PCR analysis of staphylococcal enterotoxin A (SEA) to SEH, toxic shock syndrome toxin 1, and Panton-Valentine leukocidin. Thirteen established PFGE types were recognized among these isolates, although USA100 and USA300 predominated, accounting for 53.2% and 31.4% of the isolates, respectively. As expected, isolates from hospital onset cases were predominantly USA100, whereas those from community-associated cases were predominantly USA300. USA100 isolates were diverse (Simpson's discriminatory index [DI] = 0.924); generally positive only for enterotoxin D (74.5%); and resistant to clindamycin (98.6%), erythromycin (99.0%), and levofloxacin (99.6%), in addition to β-lactam agents. USA300 isolates were less diverse (DI = 0.566), positive for Panton-Valentine leukocidin (96.3%), and resistant to erythromycin (94.1%) and, less commonly, levofloxacin (54.6%), in addition to β-lactam agents. This collection provides a reference collection of MRSA isolates associated with invasive disease, collected in 2005 and 2006 in the United States, for future comparison and ongoing studies.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/JCM.02264-08
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2009
    detail.hit.zdb_id: 1498353-9
    detail.hit.zdb_id: 390499-4
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  • 5
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    Holotoxin Activity of Botulinum Neurotoxin Subtype A4 Originating from a Nontoxigenic Clostridium botulinum Expression System
    American Society for Microbiology ; 2014
    In:  Applied and Environmental Microbiology Vol. 80, No. 23 ( 2014-12), p. 7415-7422
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 80, No. 23 ( 2014-12), p. 7415-7422
    Abstract: Clostridium botulinum subtype A4 neurotoxin (BoNT/A4) is naturally expressed in the dual-toxin-producing C. botulinum strain 657Ba at 100× lower titers than BoNT/B. In this study, we describe purification of recombinant BoNT/A4 (rBoNT/A4) expressed in a nonsporulating and nontoxigenic C. botulinum expression host strain. The rBoNT/A4 copurified with nontoxic toxin complex components provided in trans by the expression host and was proteolytically cleaved to the active dichain form. Activity of the recombinant BoNT/A4 in mice and in human neuronal cells was about 1,000-fold lower than that of BoNT/A1, and the recombinant BoNT/A4 was effectively neutralized by botulism heptavalent antitoxin. A previous report using recombinant truncated BoNT/A4 light chain (LC) expressed in Escherichia coli has indicated reduced stability and activity of BoNT/A4 LC compared to BoNT/A1 LC, which was surmounted by introduction of a single-amino-acid substitution, I264R. In order to determine whether this mutation would also affect the holotoxin activity of BoNT/A4, a recombinant full-length BoNT/A4 carrying this mutation as well as a second mutation predicted to increase solubility (L260F) was produced in the clostridial expression system. Comparative analyses of the in vitro , cellular, and in vivo activities of rBoNT/A4 and rBoNT/A4-L260F I264R showed 1,000-fold-lower activity than BoNT/A1 in both the mutated and nonmutated BoNT/A4. This indicates that these mutations do not alter the activity of BoNT/A4 holotoxin. In summary, a recombinant BoNT from a dual-toxin-producing strain was expressed and purified in an endogenous clostridial expression system, allowing analysis of this toxin.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01795-14
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2014
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    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 6
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    Immunoprecipitation of Native Botulinum Neurotoxin Complexes from Clostridium botulinum Subtype A Strains
    American Society for Microbiology ; 2015
    In:  Applied and Environmental Microbiology Vol. 81, No. 2 ( 2015-01-15), p. 481-491
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 81, No. 2 ( 2015-01-15), p. 481-491
    Abstract: Botulinum neurotoxins (BoNTs) naturally exist as components of protein complexes containing nontoxic proteins. The nontoxic proteins impart stability of BoNTs in the gastrointestinal tract and during purification and handling. The two primary neurotoxin complexes (TCs) are (i) TC1, consisting of BoNT, nontoxin-nonhemagglutinin (NTNH), and hemagglutinins (HAs), and (ii) TC2, consisting of BoNT and NTNH (and possibly OrfX proteins). In this study, BoNT/A subtypes A1, A2, A3, and A5 were examined for the compositions of their TCs in culture extracts using immunoprecipitation (IP). IP analyses showed that BoNT/A1 and BoNT/A5 form TC1s, while BoNT/A2 and BoNT/A3 form TC2s. A Clostridium botulinum host strain expressing recombinant BoNT/A4 (normally present as a TC2) from an extrachromosomal plasmid formed a TC1 with complexing proteins from the host strain, indicating that the HAs and NTNH encoded on the chromosome associated with the plasmid-encoded BoNT/A4. Strain NCTC 2916 (A1/silent B1), which carries both an ha silent bont/b cluster and an orfX bont / a1 cluster, was also examined. IP analysis revealed that NCTC 2916 formed only a TC2 containing BoNT/A1 and its associated NTNH. No association between BoNT/A1 and the nontoxic proteins from the silent bont/b cluster was detected, although the HAs were expressed as determined by Western blotting analysis. Additionally, NTNH and HAs from the silent bont/b cluster did not form a complex in NCTC 2916. The stabilities of the two types of TC differed at various pHs and with addition of KCl and NaCl. TC1 complexes were more stable than TC2 complexes. Mouse serum stabilized TC2, while TC1 was unaffected.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.02817-14
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2015
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    detail.hit.zdb_id: 1478346-0
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  • 7
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    Pseudomonas putida Septicemia in a Special Care Nursery Due to Contaminated Flush Solutions Prepared in a Hospital Pharmacy
    American Society for Microbiology ; 2005
    In:  Journal of Clinical Microbiology Vol. 43, No. 10 ( 2005-10), p. 5316-5318
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 43, No. 10 ( 2005-10), p. 5316-5318
    Abstract: Pseudomonas putida bloodstream infections were reported in two preterm neonates from a special care nursery. An unopened container of preservative-free heparin flush, compounded several weeks earlier in the hospital pharmacy and from the same batch that was administered to the patients, grew P. putida with a pulsed-field gel electrophoresis (PFGE) pattern identical to that of the patients' isolates. Intrinsic contamination was ruled out by the absence of similar reports from other hospitals and by sterility testing of unopened stock solutions. We investigated the in vitro persistence of P. putida in heparinized saline: even under refrigerated conditions, inocula of 10 2 and 10 3 CFU/ml exhibited growth at 21 and 35 days, respectively. These findings highlight the need for compliance with current standards of aseptic technique and quality assurance during the preparation of compounded sterile products.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/JCM.43.10.5316-5318.2005
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2005
    detail.hit.zdb_id: 1498353-9
    detail.hit.zdb_id: 390499-4
    SSG: 12
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  • 8
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    Efficacy and Safety of Topical Lysostaphin Treatment of Persistent Nasal Carriage of Staphylococcus aureus
    American Society for Microbiology ; 1971
    In:  Applied Microbiology Vol. 22, No. 3 ( 1971-09), p. 446-450
    Details
    In: Applied Microbiology, American Society for Microbiology, Vol. 22, No. 3 ( 1971-09), p. 446-450
    Abstract: The efficacy of lysostaphin nasal spray and Neosporin ointment (Burroughs Wellcome & Co.) in altering nasal carriage of Staphylococcus aureus was studied with persistent carriers in an institution for mentally retarded children and adults. Treatment for 5 days with either agent significantly reduced carriage rates. This effect persisted through the 5th day after therapy with lysostaphin but not with Neosporin. By the 11th day after therapy, carriage rates in the treatment and control groups were not significantly different. Except for a single immediate wheal and flair skin test reaction, no other evidence of adverse reactions to topical lysostaphin was detected. No consistent changes in hemagglutination-inhibition titers to lysostaphin were observed after therapy. Lysostaphin appears to be slightly more effective than conventional topical antimicrobial therapy in reducing nasal carriage of staphylococci in this rigorously defined population of persistent carriers.
    Type of Medium: Online Resource
    ISSN: 0003-6919
    URL: Article
    DOI: 10.1128/am.22.3.446-450.1971
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1971
    detail.hit.zdb_id: 207801-6
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  • 9
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    Efficacy and Safety of Topical Lysostaphin Treatment of Persistent Nasal Carriage of Staphylococcus aureus
    American Society for Microbiology ; 1971
    In:  Applied Microbiology Vol. 22, No. 3 ( 1971), p. 446-450
    Details
    In: Applied Microbiology, American Society for Microbiology, Vol. 22, No. 3 ( 1971), p. 446-450
    Type of Medium: Online Resource
    ISSN: 0003-6919
    URL: Article
    DOI: 10.1128/AEM.22.3.446-450.1971
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1971
    detail.hit.zdb_id: 207801-6
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  • 10
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    Evaluation of the Efficacy of Methyl Bromide in the Decontamination of Building and Interior Materials Contaminated with Bacillus anthracis Spores
    American Society for Microbiology ; 2016
    In:  Applied and Environmental Microbiology Vol. 82, No. 7 ( 2016-04), p. 2003-2011
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 82, No. 7 ( 2016-04), p. 2003-2011
    Abstract: The primary goal of this study was to determine the conditions required for the effective inactivation of Bacillus anthracis spores on materials by using methyl bromide (MeBr) gas. Another objective was to obtain comparative decontamination efficacy data with three avirulent microorganisms to assess their potential for use as surrogates for B. anthracis Ames. Decontamination tests were conducted with spores of B. anthracis Ames and Geobacillus stearothermophilus , B. anthracis NNR1Δ1, and B. anthracis Sterne inoculated onto six different materials. Experimental variables included temperature, relative humidity (RH), MeBr concentration, and contact time. MeBr was found to be an effective decontaminant under a number of conditions. This study highlights the important role that RH has when fumigation is performed with MeBr. There were no tests in which a ≥6-log 10 reduction (LR) of B. anthracis Ames was achieved on all materials when fumigation was done at 45% RH. At 75% RH, an increase in the temperature, the MeBr concentration, or contact time generally improved the efficacy of fumigation with MeBr. This study provides new information for the effective use of MeBr at temperatures and RH levels lower than those that have been recommended previously. The study also provides data to assist with the selection of an avirulent surrogate for B. anthracis Ames spores when additional tests with MeBr are conducted.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.03445-15
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2016
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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