Marilyn C Roberts

Marilyn C Roberts
University of Washington Seattle | UW · Department of Environmental and Occupational Health Sciences

45
 · 
PhD

About

288
Publications
47,553
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14,369
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Introduction
Marilyn C Roberts currently works at the Department of Environmental and Occupational Health Sciences, University of Washington Seattle. Marilyn does research in Infectious Diseases. One of their current project is 'Nepalese shrines" a hotspot for pathogen exchange between primates and humans?.'

Publications

Publications (288)
Article
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Background: Limited studies have investigated the microbial diversity of wild marine mammals. Objectives: This study characterized Escherichia coli isolates collected from fresh faecal samples of endangered southern resident killer whales (Orcinus orca) located by detection dogs. Methods: WGS of each strain was done to determine ST (using MLST...
Chapter
This chapter discusses bacterial resistance to tetracycline. Antibiotic resistance genes have co‐evolved with antibiotic producing organisms in the soil and in other environments, with many genes originating in antibiotic producing microbes. A lack of tetracycline resistance genes was also found in early enterococci and Neisseria gonorrhoeae. Mutat...
Article
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Methicillin-resistant Staphylococcus aureus (MRSA) were identified in macaques, their environmental facility, and nasal cultures of personnel from the Washington National Primate Research Center [WaNPRC] and included MRSA ST188 SCCmec IV and MRSA ST3268 SCCmec V. The aim of the current study was to determine the carriage of virulence genes, antibio...
Article
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Dairy farming involves frequent contact among animals, workers and farm environments. To explore the Staphylococcus spp. diversity that occurs on dairy farms, a pilot study sampled dairy workers, cows, and the farm environments from five farms, two organic and three conventional farms, in Washington State. Samples were taken from the nares and hand...
Article
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Swine nasal samples [n = 282] were collected from 12 randomly selected farms around Kathmandu, Nepal, from healthy animals. In addition, wild monkey (Macaca mulatta) saliva samples [n = 59] were collected near temples areas in Kathmandu using a non-invasive sampling technique. All samples were processed for MRSA using standardized selective media a...
Article
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During the past decades resistance to virtually all antimicrobial agents has been observed in bacteria of animal origin. This chapter describes in detail the mechanisms so far encountered for the various classes of antimicrobial agents. The main mechanisms include enzymatic inactivation by either disintegration or chemical modification of antimicro...
Chapter
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Antibiotic use has steadily increased since these agents were introduced in the 1940s. Millions of metric tons of antibiotics have been produced and used worldwide, which has led to contamination of both natural and man-made environments. Antibiotics are used on domestic animals, aquacultured fish, crops, and man. Because of the widespread use of a...
Article
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Little is known about exposure to pathogenic bacteria among industrial laundry workers who work with soiled clinical linen. To study worker exposures, an assessment of surface contamination was performed at an industrial laundry facility serving hospitals in Seattle, WA, USA. Surface swab samples (n = 240) from the environment were collected during...
Chapter
Antibiotic use has steadily increased since its introduction in the 1940s. This has led to millions of metric tons of antibiotics produced and used worldwide with contamination of both natural and man-made environments, as well as domestic and wild animals, man, and plants. This contamination has influenced the increase in antibiotic resistance ove...
Chapter
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This chapter reviews the roles that wastewater treatment plants (WWTPs) and their products play as reservoirs and potential amplifiers of antibiotic resistant bacterias (ARBs) and antibiotic resistance genes (ARGs), their role in bacterial diversity and/or transmission through the lens of a One Health perspective, and their influence on the health...
Chapter
Tetracyclines are broad-spectrum antibiotics that bind to the elongating ribosome and inhibit delivery of the ternary complex EF-Tu, GTP, and aminoacylated-tRNA to the A-site [1–3]. The primary binding site of tetracycline is located in the helix 34 (h34) of the 16S rRNA in the 30S subunit which overlaps the anticodon stem-loop of the A-site tRNA [...
Article
Background: Enterococcus spp. are a normal part of the gastrointestinal tract of humans and animals. They are also important pathogens, being responsible for 14% of US nosocomial infections from 2007 to 2010. Aim: To examine a laundry facility that processes clinical linens for the presence and seasonality of vancomycin-resistant Enterococcus sp...
Article
Clostridium difficile is both a hospital and community acquired pathogen. The current study determined if C. difficile could be cultured from clinical laundry facility surfaces. A total of 240 surface samples were collected from dirty areas (n = 120), which handle soiled clinical linens, and from clean areas (n = 120), which process and fold the cl...
Article
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Purpose: To evaluate the efficacy of xylitol-sweetened milk as a caries-preventive strategy. Methods: In this nine-month prospective proof-of-principle trial, Peruvian schoolchildren were randomized to one of five different milk groups: (1) eight g of xylitol per 200 mL milk once per day; (2) four g of xylitol per 100 mL milk twice per day; (3)...
Article
Objectives: MDR MRSA isolates cultured from primates, their facility and primate personnel from the Washington National Primate Research Center were characterized to determine whether they were epidemiologically related to each other and if they represented common local human-associated MRSA strains. Methods: Human and primate nasal and composit...
Article
Aim: Examine a clinical laundry facility for the presence of methicillin-resistant Staphylococcus aureus (MRSA) on environmental surfaces and among personnel. Methods: Nasal and face samples along with surface samples were collected four times in 2015. MRSA isolates were confirmed using standardized biochemical assays and molecular characterizat...
Article
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Objectives: The objective of this study was to identify the molecular mechanism of macrolide resistance in the actinomycete Rhodococcus equi, a major equine pathogen and zoonotic agent causing opportunistic infections in people. Methods: Macrolide-resistant (n¼ 62) and macrolide-susceptible (n¼ 62) clinical isolates of R. equi from foals in the USA...
Article
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We evaluated in vitro activity of delafloxacin against a panel of 117 Neisseria gonorrhoeae including 110 clinical isolates collected from 2012 – 2015 and seven reference strains, compared with the activities of seven antimicrobials currently or previously recommended for treatment of gonorrhea. We examined the potential for delafloxacin to select...
Article
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The presence of antibiotic drug residues, antibiotic resistant bacteria, and antibiotic resistance genes in agroecosystems has become a significant area of research in recent years and is a growing public health concern. While antibiotics are used in both human medicine and agricultural practices, the majority of their use occurs in animal producti...
Article
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Vancomycin-resistant enterococci [VRE] have been isolated from municipal, hospital and agricultural wastewater, recreational beaches, wild animals, birds and food animals around the world. In this study, American crows (Corvus brachyrhynchos) from sewage treatment plants (WWTP), dairy farms, and a large roost in a restored wetland with correspondin...
Article
Full-text available
Objectives: The objective of this study was to identify the molecular mechanism of macrolide resistance in the actinomycete Rhodococcus equi, a major equine pathogen and zoonotic agent causing opportunistic infections in people. Methods: Macrolide-resistant (n = 62) and macrolide-susceptible (n = 62) clinical isolates of R. equi from foals in th...
Book
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Antibiotics represent one of the most successful forms of therapy in medicine. But the efficiency of antibiotics is compromised by the growing number of antibiotic-resistant pathogens. Antibiotic resistance, which is implicated in elevated morbidity and mortality rates as well as in the increased treatment costs, is considered to be one of the majo...
Article
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Antibiotics represent one of the most successful forms of therapy in medicine. But the efficiency of antibiotics is compromised by a growing number of antibiotic-resistant pathogens. Antibiotic resistance, which is implicated in elevated morbidity and mortality rates as well as in the increased treatment costs, is considered to be one of the major...
Article
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Recent reports have speculated on the future impact that antibiotic-resistant bacteria will have on food production, human health, and global economics. This review examines microbial resistance to tetracyclines and phenicols, antibiotics that are widely used in global food production. The mechanisms of resistance, mode of spread between agricultur...
Article
Background: Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S aureus (MSSA) were isolated from environment surfaces sampled from 33 Washington State fire stations. Methods: Samples were collected by fire personnel using commercial testing swabs. One to 6 surfaces were sampled per swab with 20 swabs per station. Bio...
Article
Tetracycline continues to be used as treatment for a variety of infections due to Gram-positive, Gram-negative, intracellular bacteria, some protozoan infections, and noninfectious conditions [12, 65]. Tetracycline is also an important antibiotic for prophylaxis or treatment either alone or in combination with other antibiotics and for agents of bi...
Article
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Over the last decade community-acquired methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major cause of disease in the general population with no health care exposure or known classical risk factors for MRSA infections. The potential community reservoirs have not been well defined though certain strains such as ST398 and USA300 h...
Article
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The anterior nares is the site of choice for the Veterans Administration methicillin-resistant Staphylococcus aureus (MRSA) surveillance program; however, correlation between nares colonization and concomitant wound infections has not been well established. The purpose of this study was threefold: to determine the relatedness of MRSA isolates from...
Article
The aim of the study was to determine the spatial distribution of methicillin-resistant Staphylococcus aureus (MRSA) at two marine and one freshwater recreational beaches in the Seattle area. Fifty-six marine water, 144 freshwater, and 96 sand samples were collected from June through August 2010. Isolates were biochemically verified as MRSA. Staphy...
Article
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Methicillin-resistant Staphylococcus aureus (MRSA) isolated from frequently touched dental school clinic surfaces were compared with MRSA isolated nasal cultures of dental students. Sixty-one dental students and 95 environmental surfaces from 7 clinics were sampled using SANICULT (Starplex Scientific Inc, Etobicoke, Ontario, Canada) swabs. Antimicr...
Article
Recent studies have found variable levels of methicillin-resistant Staphylococcus aureus [MRSA] in marine water from temperate and warmer climates suggesting that temperature may play a role in survival of MRSA in the environment. The aim of the study was to compare the survival of clinical and environmental MRSA and MSSA strains in fresh and marin...
Article
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Bacteria can become resistant to antibiotics by mutation, transformation, and/or acquisition of new genes which are normally associated with mobile elements (plasmids, transposons, and integrons). Mobile elements are the main driving force in horizontal gene transfer between strains, species, and genera and are responsible for the rapid spread of p...
Article
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Recreational beach environments have been recently identified as a potential reservoir for methicillin-resistant Staphylococcus aureus (MRSA); however, accurate quantification methods are needed for the development of risk assessments. This novel most-probable-number approach for MRSA quantification offers improved sensitivity and specificity by co...
Article
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Isolation and characterization of methicillin-resistant Staphylococcus aureus (MRSA) from frequently touched nonhospital environmental surfaces at a large university, student homes and community sites. Twenty-four isolates from 21 (4·1%, n = 509) surfaces were MRSA positive and included 14 (58%, n = 24) SCCmec type IV, two (8%, n = 24) type I, and...
Article
Full-text available
Methicillin-resistant Staphylococcus aureus (MRSA) strains were isolated and characterized from environmental surfaces of two fire stations from two independent districts in the northwestern United States. After the first sampling and before the second sampling, education was provided, additional signage was added, and changes in disinfection proto...
Article
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to determine the mechanism(s) of macrolide resistance in Haemophilus influenzae isolated from cystic fibrosis (CF) patients participating in a randomized placebo-controlled trial of azithromycin. macrolide susceptibility, mutations and carriage of the macrolide resistance genes erm(A), erm(B), erm(C), erm(F) and mef(A) were determined using PCR ass...
Article
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The aim of this study was to isolate and characterize methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus spp. (MRCoNS) from marine water and intertidal beach sand from public beaches in Washington State, USA. Fifty-one staphylococci from Washington State beaches were characterized using an...
Article
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To evaluate the effectiveness of a xylitol pediatric topical oral syrup to reduce the incidence of dental caries among very young children and to evaluate the effect of xylitol in reducing acute otitis media in a subsequent study. Double-blind randomized controlled trial. Communities in the Republic of the Marshall Islands. One hundred eight childr...
Article
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The objective of this study was to determine antibiotic resistance patterns and specific resistance genes in Gram-negative enteric bacteria recovered from 42 different drinking water sources servicing 2 rural villages in south-western Uganda. These water sites were prone to contamination by both human and cattle activity. Of the 52 isolates examine...
Article
The aim of the study was to determine if vancomycin-resistant Enterococcus spp. [VRE] carrying vanA and/or vanB genes were present in public marine beaches and a fishing pier [2001-2003, 2008] from Washington and California [2008]. PCR assays for the vanA and/or vanB genes with verification by DNA-DNA hybridization of the PCR products were used. Po...
Article
The tet(X) gene has previously been found in obligate anaerobic Bacteroides spp., which is curious because tet(X) encodes for a NADP-dependent monooxygenase that requires oxygen to degrade tetracycline. In this study, we characterized a tetracycline resistant, aerobic, Gram-negative Sphingobacterium sp. strain PM2-P1-29 that harbours a tet(X) gene....
Chapter
Full-text available
Tetracycline resistance (Tcr) is most often due to the acquisition of new genes, which code for energy-dependent effl ux of tetracyclines, or for a protein that protects bacterial ribosomes from the action of tetracyclines. Many of these genes are associated with mobile plasmids or transposons and can be distinguished from each other using molecula...
Article
To determine if environmental Clostridium perfringens carry antibiotic resistance genes and if the genes are mobile. Clostridium perfringens from water, soil and sewage (2003-2006) were screened for the tetracycline and macrolide resistance genes previously described in animal and human C. perfringens [erm(B), erm(Q), tetA(P), tetB(P) and tet(M) ge...
Conference Paper
Background: Vancomycin resistant enterococci [VRE] outside the health-care setting were first identified in the EU in 1993, while VRE had not been identified outside healthcare settings in North America until two recent reports of two vanA Enterococcus faecalis from hospital impacted sewage and 11 uncharacterized VRE from water impacted by a concen...
Article
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Three cohorts of juvenile and subadult Chinook salmon Oncorhynchus tshawytscha received multiple treatments with macrolide antibiotics for bacterial kidney disease (BKD) during rearing in a captive broodstock program. A total of 77 mortalities among the cohorts were screened for Renibacterium salmoninarum, the etiologic agent of BKD, by agar cultur...
Data
Gummy bear study baseline health questionnaire. Questionnaire used to obtain descriptive and general health information.
Article
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Habitual consumption of xylitol reduces mutans streptococci (MS) levels but the effect on Lactobacillus spp. is less clear. Reduction is dependent on daily dose and frequency of consumption. For xylitol to be successfully used in prevention programs to reduce MS and prevent caries, effective xylitol delivery methods must be identified. This study e...
Article
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The aim of this study was to characterize a novel conjugative transposon Tn6009 composed of a Tn916 linked to a Staphylococcus aureus mer operon in representative Gram-positive and Gram-negative bacteria isolated in Nigeria and Portugal. Eighty-three Gram-positive and 34 Gram-negative bacteria were screened for the presence of the Tn6009 using DNA-...
Article
Mercury emitted from dental amalgam may select for increased numbers of antibiotic- or mercury-resistant commensal bacteria in patients and increase their risk for bacterial diseases that are resistant to common therapies. We hypothesized that the presence of dental amalgams would increase the level of mercury-, tetracycline-, ampicillin-, erythrom...
Article
This Minireview summarizes the changes in the field of bacterial resistance to macrolide, lincosamide, streptogramin, ketolide, and oxazolidinone (MLSKO) antibiotics since the nomenclature review in 1999. A total of 66 genes conferring resistance to this group of antibiotics has now been identified and includes 13 new rRNA methylase genes, four ATP...
Article
Full-text available
The majority of people in developing nations rely on untreated or minimally treated surface and shallow groundwater sources which are prone to faecal contamination. This study evaluated the utility of EC 3M™ Petrifilm™ and sanitary inspection forms (SIFs) as tools to assess 47 water sources and identify hazards of contamination in two rural Ugandan...
Article
Full-text available
Xylitol chewing gum has been shown to reduce Streptococcus mutans levels and decay. Two studies examined the presence and time course of salivary xylitol concentrations delivered via xylitol-containing pellet gum and compared them to other xylitol-containing products. A within-subjects design was used for both studies. Study 1, adults (N = 15) rece...
Article
Full-text available
The majority of people in developing nations rely on untreated or minimally treated surface and shallow groundwater sources which are prone to faecal contamination. This study evaluated the utility of EC 3M Petrifilm and sanitary inspection forms (SIFs) as tools to assess 47 water sources and identify hazards of contamination in two rural Ugandan v...
Article
Full-text available
This study examined bacterial contamination levels from 47drinking water sources(92%were surface sources)from two rural Ugandan villages using EC 3M TM petrifilmsTM incubated for 24 h at 37ºC. E. coli counts in 1ml water samples ranged from 0-120 cfu/ml. Confirmation of presumptive E. coli was performed by transferring colonies onto Blood agar foll...
Article
Full-text available
In this study, multidrug-resistant bacteria previously recovered from the indoor air of a large-scale swine-feeding operation were tested for the presence of five macrolide, lincosamide and streptogramin (MLS) resistance genes and five tetracycline (tet) resistance genes. Enterococcus spp. (n = 16) and Streptococcus spp. (n =16) were analysed using...
Article
Full-text available
To determine antibiotic resistance genes associated with 17 Nigerian CTX-M-positive Klebsiella pneumoniae plasmids from patients with community-acquired urinary tract infections. The size and restriction patterns of the plasmids were determined, and antibiotic resistance genes were identified using DNA-DNA hybridization, PCR assays, hybridization o...
Article
A strain of multidrug-resistant Acinetobacter baumannii that caused a 26% mortality rate in a French epidemic was characterized and compared with an antibiotic-susceptible strain of A. baumannii. The multiresistant strain carries many of its antibiotic-resistance genes on an 86-kb region, whereas the susceptible strain lacks these genes in a homolo...
Article
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To determine whether mef(A)-msr(D) and tet(M) genes are linked in representative Gram-negative isolates and/or transferred together during conjugation. To molecularly characterize the Acinetobacter junii element and compare the structure and sequence with the non-conjugative Streptococcus pneumoniae Tn2009 element. PCR assays, DNA-DNA hybridization...