Molecular characteristics of Staphylococcus aureus isolated from employees, children, and environmental surfaces in Iowa child daycare facilities

Genetic characterization of Staphylococcus aureus isolated from Norway rats in Boston, Massachusetts

BACKGROUND

Despite the importance of domesticated animals in the generation and transmission of antibiotic-resistant Staphylococcus aureus, the role of wild animals, specifically rodents, in the ecology of S. aureus remains unclear. We recovered and genotyped S. aureus isolates from wild Norway rats (Rattus norvegicus) in Boston, Massachusetts to examine genetic relationships between common human and animal S. aureus isolates in a large US metropolitan area.

METHODS

We collected and necropsied 63 rats from June 2016 to June 2017. Nasal, foot pad, fur, and fecal swabs were collected. Staphylococcus aureus was isolated using culture-based methods and polymerase chain reaction confirmation. S. aureus isolates were spa typed, tested for antibiotic susceptibility, and whole genome sequenced. Assembled sequences were uploaded to the Comprehensive Antibiotic Resistance Database to identify antibiotic resistance elements. A phylogenetic tree was constructed using the neighbor-joining method with the maximum composite likelihood distance in MEGA7.

RESULTS

We recovered 164 Gram-positive bacterial isolates from Norway rats. Nineteen isolates from eight individual rats were confirmed as S. aureus (prevalence: 12.9% (8/63)). All S. aureus isolates were methicillin-susceptible S. aureus (MSSA), pvl-negative, and resistant to penicillin. Two isolates displayed resistance to erythromycin. Four different S. aureus spa types were detected (t933, t10751, t18202, and t189). Thirteen unique antibiotic resistance elements were identified, and all isolates shared genes mepR, mgrA, arlR, and S. aureus norA. Phylogenetic analysis if the 19 S. aureus isolates revealed they were genetically similar to four clades of S. aureus with similar resistance gene profiles isolated from both human- and animal-derived S. aureus, as well as formed a distinct phylogenetic cluster composed only of rat isolates.

CONCLUSIONS

Wild rodents may serve as a reservoir or vector of antibiotic resistance genes in the urban environment with relevance for human and animal health.

The occurrence of antibiotic-resistant bacteria on the clothes of nursery teachers in daycare centres

AIMS

Childcare facilities act as microenvironments that facilitate and promote the selection, spread, and transmission of antibiotic-resistant microorganisms in the community. We focused on the study of antimicrobial resistance and genetic predispositions for β-lactamase production in bacterial isolates from nursery teachers' clothing.

METHODS AND RESULTS

Antimicrobial resistance of bacterial strains belonging to Enterobacteriaceae, Enterococcus, Staphylococcus spp., Pseudomonas spp. and Bacillus spp. isolated from 80 samples of nursery teachers' clothing was determined. The selected ESβL genes were found in 30 (44.1%) of 68 strains examined. The CTX-M type ESβL determinants were detected in 15.4%, 71.5%, and 42.5% of the Enterobacteriaceae, Pseudomonas, and Bacillus isolates, respectively. The OXA-type coding genes were detected only in strains of the genera Pseudomonas (57.1%) and Bacillus (48.6%). Thus, most B. cereus strains were sensitive to the recommended antibiotics used to treat infections caused by these bacteria. Methicillin resistance was phenotypically confirmed in 27 (14.6%) of 185 staphylococcal isolates. Four isolates (2.2%) were identified as MRSA. Vancomycin resistance was not observed in any of the staphylococcal and enterococci strains.

CONCLUSIONS

This study has shown that potential pathogens have been isolated from the clothing of nursery teachers, posing a risk of transmission to children. These clothes should be maintained and properly laundered to avoid cross-contamination and the spread of multidrug-resistant (MDR) bacteria in childcare centres.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides insight into the route of transmission of MDR microorganisms through the clothing of nursery teachers, to which greater importance should be given in the future. Proper procedures for the cleaning and use of clothing in daycare centres should be clarified and standardised.

Spa Typing of Staphylococcus aureus in a Neonatal Intensive Care Unit During Routine Surveillance

BACKGROUND

Staphylococcus aureus protein A (spa) typing can be used to expand characterization of the epidemiology of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in neonatal intensive care units (NICU).

METHODS

From January 2017 to June 2018, twice-monthly surveillance for S. aureus was performed in an academically affiliated NICU. Decolonization of infants colonized with S. aureus included chlorhexidine gluconate bathing and/or mupirocin for those with mupirocin-susceptible strains. Spa typing and mupirocin-resistance testing were performed. Demographic and clinical characteristics were compared between infants colonized with MSSA vs MRSA and infants with and without the most common MSSA spa type, MSSA-t279.

RESULTS

Overall, 14% and 2% of 1556 hospitalized infants had positive surveillance cultures for MSSA and MRSA, respectively. Thirty-six infants harbored unique MSSA spa types, 5 infants harbored unique MRSA spa types, and 30 MSSA and 6 MRSA spa types were identified in ≥2 infants. No outbreaks were identified during the study period. MSSA-t279 was isolated from 3% of infants and largely detected from infants hospitalized in one section of the NICU; 96% of t279 isolates were mupirocin resistant. Infection rates, length of hospitalization, and mortality were similar among infants initially colonized with t279 vs other MSSA spa types.

CONCLUSIONS

The MSSA colonization burden was 5-fold larger than that of MRSA. Numerous unique spa types were identified. The most common spa type, MSSA-t279, was not associated with increased morbidity or mortality but was mupirocin resistant and associated with clustered NICU beds. This suggests potential transmission from the environment, shared staff, and/or workflow issues requiring further study. Other decolonization strategies for S. aureus in the NICU are needed.

Methicillin Resistant Staphylococcus aureus and public fomites: a review

Staphylococcus genus is a Gram-positive coccus normally associated with skin and mucous membranes of warm-blooded animals. It is part of the commensal human microflora, or found in animals, or contaminating surfaces in the community and hospital settings. Staphylococcus aureus is the most pathogenic species belonging to this genus, as it possesses a collection of virulence factors that are expressed solely to evade the immune system. The increase in the misuse of antimicrobial agents predisposed S. aureus to develop antibiotic resistance, including the resistance to methicillin which led to the emergence of Methicillin-Resistant S. aureus (MRSA). MRSA is considered one of the most dangerous nosocomial pathogens causing many hard to treat infections in hospitals and was named as Hospital Associated MRSA (HA-MRSA). Over the past 20-25 years, MRSA was isolated from community settings and thus Community Associated MRSA (CA-MRSA) has emerged. Inside hospitals, MRSA has been isolated from fomites in contact with patients, as well as staff's protective and personal items. This review highlights the worldwide prevalence of MRSA on fomites within the contexts of hospital and community settings.

Airborne Staphylococcus aureus in different environments-a review

The aim of the literature review was to describe the environments where the presence of airborne Staphylococcus aureus was confirmed and to catalogue the most often used methods and conditions of bioaerosol sampling to identify the bacteria. The basis for searching of studies on S. aureus in the bioaerosol in different environments was PubMed database resources from the years 1990-2019 (May). The review included studies which were carried on in selected environments: hospitals and other health care facilities, large-scale animal breeding, wastewater treatment plants, residential areas, educational institutions, and other public places. The highest concentrations and genetic diversity of identified S. aureus strains, including MRSA (methicillin-resistant S. aureus), have been shown in large-scale animal breeding. The role of the airborne transmission in dissemination of infection caused by these pathogens is empirically confirmed in environmental studies. Commonly available, well-described, and relatively inexpensive methods of sampling, identification, and subtyping guarantee a high reliability of results and allow to obtain fast and verifiable outcomes in environmental studies on air transmission routes of S. aureus strains.

Infection from Outdoor Sporting Events-More Risk than We Think?

Competitive sports that involve extensive contact with mud are commonly held events and growing in popularity. However, the natural environment contributes to infection risks, and these events have been implicated in multiple infectious disease outbreaks. Soils and mud contain rich microbial communities and can include pathogens (including viruses, bacteria, and parasites), thereby offering risk of infection; there is also a risk of disease due to shedding, by participants, of pathogens directly into the environment. These disease risks are ubiquitous and are present in the most developed countries, as well as elsewhere. Prevention of the further spread of mud sport-related infections through secondary infections to non-participant community members is of critical importance. We recommend shifts in practice and policy, such as site condition monitoring, improved messaging with regards to infections risk, and implementation of pre- and post-event wash stations to reduce these risks.

Prevalence and Molecular Characterization of Staphylococcus aureus and Methicillin-resistant S. aureus on Children's Playgrounds

BACKGROUND

Staphylococcus aureus is a major public health concern due to the emergence of virulent and drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA). Although numerous studies have been conducted to assess the environmental contamination of S. aureus in health care and household settings, little is known about the prevalence and epidemiology of S. aureus, including MRSA, on environmental surfaces of children's playgrounds. This study investigated the prevalence and molecular epidemiology of S. aureus and MRSA at playgrounds in northeast Ohio.

METHODS

A total of 280 environmental samples were collected from 10 playgrounds in northeast Ohio in July 2016. Sampling sites were selected based on playground size and availability of equipment located in both small and large cities and their suburbs. Samples were analyzed using established microbiology methods, and resulting S. aureus isolates were typed by spa typing. Polymerase chain reaction was used to detect the presence of the Panton-Valentine leukocidin and mec A genes. Antibiotic susceptibility was tested via the Vitek-2 System.

RESULTS

The overall prevalence of S. aureus and MRSA was 31.8% (89/280) and 3.9% (11/280), respectively. A total of 43 spa types were detected from 257 S. aureus isolates. Overall, t189 was the most common spa type, accounting for 15.6% (40/257) of the isolates. Sixteen isolates (6.2%) were t002 (ST5/USA100), a common hospital-associated strain, and 11 isolates (4.3%) were t008 (ST8/USA300), a common community-associated strain. Five livestock-associated strain (t571/ST398) were also identified. Twenty-nine (11.3%) isolates were resistant to oxacillin, and 66 (25.7%) were multi-drug resistant S. aureus.

CONCLUSIONS

The results of this study indicate that environmental surfaces of playgrounds in northeastern Ohio were contaminated with S. aureus and MRSA. These data reinforce the need for implementing effective prevention strategies to mitigate the risk imposed to children by environmental contamination of MRSA.

Characterizing the molecular epidemiology of Staphylococcus aureus across and within fitness facility types

BACKGROUND

Staphylococcus aureus is a common bacterium found in the nose and throat of healthy individuals, and presents risk factors for infection and death. We investigated environmental contamination of fitness facilities with S. aureus in order to determine molecular types and antibiotic susceptibility profiles of contaminates that may be transmitted to facility patrons.

METHODS

Environmental swabs (n = 288) were obtained from several fitness facilities (n = 16) across Northeast Ohio including cross-fit type facilities (n = 4), traditional iron gyms (n = 4), community center-based facilities (n = 5), and hospital-associated facilities (n = 3). Samples were taken from 18 different surfaces at each facility and were processed within 24 h using typical bacteriological methods. Positive isolates were subjected to antibiotic susceptibility testing and molecular characterization (PVL and mecA PCR, and spa typing).

RESULTS

The overall prevalence of S. aureus on environmental surfaces in the fitness facilities was 38.2% (110/288). The most commonly colonized surfaces were the weight ball (62.5%), cable driven curl bar, and CrossFit box (62.5%), as well as the weight plates (56.3%) and treadmill handle (50%). Interestingly, the bathroom levers and door handles were the least contaminated surfaces in both male and female restroom facilities (18.8%). Community gyms (40.0%) had the highest contamination prevalence among sampled surfaces with CrossFit (38.9%), traditional gyms (38.9%), and hospital associated (33.3%) contaminated less frequently, though the differences were not significant (p = 0.875). The top spa types found overall were t008 (12.7%), t267 (10.0%), t160, t282, t338 (all at 5.5%), t012 and t442 (4.5%), and t002 (3.6%). t008 and t002 was found in all fitness facility types accept Crossfit, with t267 (25%), t548, t377, t189 (all 10.7%) the top spa types found within crossfit. All samples were resistant to benzylpenicillin, with community centers having significantly more strains resistant to oxacillin (52.8%), erythromycin (47%), clindamycin (36%), and ciprofloxacin (19%). Overall, 36.3% of isolates were multidrug resistant.

CONCLUSIONS

Our pilot study indicates that all facility types were contaminated by S. aureus and MRSA, and that additional studies are needed to characterize the microbiome structure of surfaces at different fitness facility types and the patrons at these facilities.

Spatial relationships among public places frequented by families plagued by methicillin-resistant Staphylococcus aureus

Objective

To understand factors associated with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) acquisition and infection, we mapped public places (including personal service establishments, fitness centers, pools, schools, and daycares) visited by members of households affected by CA-MRSA skin and soft tissue infection.

Results

From January 2012 to October 2015, households of children with CA-MRSA SSTI in metropolitan St. Louis were enrolled in the HOME: Household Observation of MRSA in the Environment study. Addresses of public places visited within 3 months of enrollment were reported by 671 participants and were analyzed using a geographic information system (GIS). The Nearest Neighbor Tool in ArcGIS assessed clustering of public places within the study region. Public places were significantly clustered within the study area compared to the expected distance between locations (p < 0.001). Additionally, one-third (48/150) of participating households visited at least one public place in common with other households. No significant relationship between participants visiting the public places within 3 months of enrollment and subsequent colonization or SSTI were found. Understanding community behavior is critical to informing public health initiatives to reduce the prevalence of CA-MRSA infections.

Antibiotic resistance and molecular characteristics of Staphylococcus aureus isolated from backyard-raised pigs and pig workers

Staphylococcus aureus is a commensal and pathogenic bacterium with impact on public health and livestock industry. The study investigated nasal carriage, antibiotic resistance, and molecular characterization of S. aureus in pigs and pig workers. Nasal swabs from 300 backyard-raised pigs and 101 pig workers were used for the study. Resulting isolates were confirmed using MALDI-TOF MS, tested for antibiotic resistance, and three different multiplex PCRs were used to detect enterotoxin, mecA, spaA, scn, and pvl genes. spa typing was used to annotate the isolates into MLST clonal complexes (CC). Structured questionnaire was used to access possible risk factors for S. aureus carriage. The prevalence of S. aureus in pigs and pig workers were 5.3 and 12.9%, respectively. The isolates were resistant to beta-lactams (97%), tetracycline (62%), sulfonamide (52%), aminoglycoside (20.6%), fluoroquinolone (24%), and mupirocin (3.4%). Twenty seven (93%) of the isolates carried scn, 7(24%) pvl, and 12 (41%) enterotoxin genes, respectively. Questionnaire survey showed medical-related occupation of household members was associated (p < 0.5) with S. aureus carriage. This study suggests the presence of human multidrug resistant strains of S. aureus, high carriage of pvl, and enterotoxin genes, and CC5, CC15, and CC152 were the CC-groups shared among pigs and pig workers.

Environmental contamination with Staphylococcus aureus at a large, Midwestern university campus

BACKGROUND

Staphylococcus aureus can cause minor to severe life-threatening infections. The changing epidemiology of S. aureus is of public health concern due to the emergence of multi-drug resistant (MDR) strains. Environmental surfaces play a crucial role in the transmission of S. aureus. The objective of this study was to examine environmental contamination and molecular characteristics of S. aureus in health professional-associated (HPA) and non-health professional-associated (NHPA) buildings at a large university.

METHODS

A total of 152 environmental surface samples were collected from two HPA and two NHPA campus buildings. Bacterial culture and diagnostics were done using standard microbiology methods. Polymerase chain reaction was conducted to detect mecA and PVL genes. All isolates were spa typed. A subset of isolates was characterized via multi-locus sequence typing (MLST). All S. aureus isolates were tested for antibiotic susceptibility.

RESULTS

The overall contamination of S. aureus and methicillin-resistant S. aureus (MRSA) was 22.4% (34/152) and 5.9% (9/152) respectively. Similar prevalence of contamination was found in HPA and NHPA buildings. A total of 17 different spa types were detected among 34 S. aureus isolates. The majority of the MRSA isolates belonged to clonal complex (CC) 8. One isolate was positive for PVL. Eleven different sequence types (STs) were detected from 17 tested isolates. ST8 was the most common. Twelve isolates (35.3%) were MDR.

CONCLUSION

Almost 27% (9/34) of the isolates were MRSA. The highest contamination of S. aureus was found in high hand-touch areas such as door knobs, suggesting that human interaction in crowded environments such as academic institutions plays a crucial role in S. aureus/MRSA transmission via inanimate objects. Additionally, more than one-third of the isolates were MDR. These data reinforce the need to implement effective prevention strategies outside the healthcare setting to decrease the incidence of drug-resistant S. aureus infections.

High prevalence of toxic shock syndrome toxin-producing epidemic methicillin-resistant Staphylococcus aureus 15 (EMRSA-15) strains in Kuwait hospitals

This study characterized EMRSA-15 isolates obtained from patients in Kuwait hospitals for their genotypic relatedness, antibiotic resistance and carriage of virulence genes using pulsed-field gel electrophoresis (PFGE), coagulase serotyping, SCCmec subtyping, spa typing, multilocus sequence typing and DNA microarray. The isolates were resistant to trimethoprim (75.6%), ciprofloxacin (29.7%), erythromycin and clindamycin (24.3%), tetracycline (19.0%), and gentamicin and kanamycin (21.6%). All 37 isolates belonged to sequence type (ST) 22, coagulase type XI, three PFGE types and eight subtypes, ten spa types including t223 (51.3%), t852 (13.5%), t032 (8.1%), t790 (8.1%), t3107 (5.4%) and one each of t309, t2251, t3935, t5708 and t5983. Twenty-six isolates (70.2%) carried SCCmec IVa, eight isolates carried SCCmec IV and three isolates carried SCCmec IVh. All isolates carried agr1, cap5 and egc gene cluster (seg, sei, selm, seln, selo, and selu). tst (toxic shock syndrome toxin) was detected in 23 isolates. Eight isolates (21.6%) were positive for Panton-Valentine leukocidin (PVL). Genotypic analysis revealed that 62.1% of the isolates comprising ST22-IVa-t223 (51.3%) and ST22-IVa-t309/t2251/t3935/t5708 (10.8%) were CC22-[tst1⁺] UK EMRSA-15/Middle Eastern variant, 21.6% were CC22-PVL⁺ EMRSA-15 variant and 16.2% were CC22-UK EMRSA-15/Barnim clone. These results show that the tst1 positive-ST22-IVa-t223 (Middle Eastern variant) and the CC22-PVL⁺ EMRSA-15 variant were the dominant EMRSA-15 variants in Kuwait hospitals.

Epidemiology of necrotizing infection caused by Staphylococcus aureus and Streptococcus pyogenes at an Iowa hospital

The present study was performed to characterize the epidemiology of necrotizing soft tissue infection caused by Streptococcus pyogenes (n=14) and Staphylococcus aureus (n=14) isolates collected at the University of Iowa Hospitals and Clinics. An additional 9 S. pyogenes isolates were collected from patients being treated for mild respiratory infections and served as a comparison sample in the analysis. Patient data corresponding to the isolates (n=37) were also collected in order to identify risk factors or comorbid conditions possibly correlated with necrotizing fasciitis (NF). The prevalence of methicillin-resistant S. aureus among the study isolates was 35.7% (5/14), and the prevalence of the Panton-Valentine leukocidin (PVL) gene was 57% (8/14). The S. pyogenes NF (wound) isolates (n=14) belonged to 10 different emm types, none of which appeared to be associated with more severe disease when compared to the milder infection (throat) samples (n=9). Comorbid conditions such as diabetes and cardiovascular disease were significantly associated with NF. The results indicate that there may be a high prevalence of the PVL virulence factor in NF infections and that spa type t008 may be responsible for the increasing incidence of S. aureus NF infections in Iowa.