Hospital-associated Methicillin-resistant Staphylococcus Aureus Research Articles

739. Impact of Alcohol-based Nasal Decolonization’s Method of Documentation in Reducing Methicillin-resistant Staphylococcus aureus Hospital-associated Infections

Abstract Background Infections related to multi-drug resistant organisms (MDRO) are increasingly difficult to treat and contribute to elevated mortality, prolonged length of stay and financial burden. At a 382-bed academic medical center, universal decolonization using an alcohol-based nasal decolonizing agent is performed twice daily on all inpatients, as well as chlorhexidine gluconate (CHG) bathing on select populations. Numerous studies cite decolonization as an effective reduction method for MDRO such as methicillin-resistant Staphylococcus aureus (MRSA). Unfortunately, documentation method is a seldomly considered variable. The purpose of this review was to evaluate the impact of documentation method for an alcohol-based nasal decolonization agent in reducing MRSA hospital-associated infections. Methods The study included all National Healthcare Safety Network (NHSN) defined hospital associated laboratory identified (Lab ID) MRSA blood infections from July 2019 through March 2023. Data was divided into descriptive categories with number of infections noted. The baseline period included population specific decolonization (n=35), followed by universal decolonization documentation via nursing task list (n=13), and concluded with electronic medication administration record (EMAR) implementation (n=7). The Kruskal Wallace Test was utilized for evaluation due to non-normative distribution. Results A Kruskal Wallace H Test indicated a statistical significance in medians between the task list and EMAR H(1) =5.10, p=0.024. There was no significance noted between the baseline and task list H(1 =0.04), p=0.841. Medians between baseline and EMAR approached significance but did not meet for this study H(1) =3.24, p=0.072. Clinically, there was a reduction in MRSA Lab ID of 48% between baseline and task list, followed by a 46% reduction between task list and EMAR. Overall reduction from baseline to EMAR was 80%. Conclusion Reduction of infection is crucial for patient safety and quality outcomes. Documentation is not typically highlighted as a risk reduction method. This study noted a significant decrease in hospital-associated MRSA Lab ID events after transition of documentation from the nursing task list to the EMAR. Disclosures All Authors: No reported disclosures

Molecular epidemiology and change trend of methicillin-resistant Staphylococcus aureus from invasive infections of a hospital in Hangzhou from 2012 to 2018.

The disease caused by methicillin-resistant Staphylococcus aureus (MRSA) is a global public health challenge that threatens society and patients seriously. Therefore, the molecular epidemiology and change trend of MRSA is essential for the control and treatment of diseases caused by the pathogen in their regions. To explore molecular epidemiology of MRSA in Hangzhou, we collected 162 MRSA isolates from 2012 to 2018, conducted the antimicrobial susceptibility and used polymerase chain reaction(PCR) to test the molecular typing including multilocus sequence typing (MLST), staphylococcal chromosome cassette mec (SCCmec), staphylococcal protein A (spa A) and Panton-Valentine leucocidin (PVL). All the strains was divided into community-associated MRSA (CA-MRSA) or hospital-associated MRSA (HA-MRSA). 162 MRSA isolates were divided into 16 STs and 30 spa types. The major ST type was ST5 (96/162, 59.3%) and the predominant spa type was t311 (83/162, 51.2%). Five SCCmec types were found and the most common SCCmec type was type II (101/162, 61.7%). ST5-II-t311 was the predominant MRSA clone. And the prevalence of ST5 MRSA gradually declined from 2014 to 2018 but the prevalence of ST59 MRSA significantly increased. At the same time, livestock-associated methicillin-resistant Staphylococcus aureus(LA-MRSA) ST398 and ST9 were detected. Twenty-eight isolates were PVL gene positive (28/162, 17.3%). The most prevalent PVL-positive clone was ST59-IVa-t437. Comparing with HA-MRSA, CA-MRSA had a lower probability of ST5 (9.1% vs 67.1%, P=0.000) but a higher probability of ST59 (63.6% vs 11.4%, P=0.000), not only that, it was more likely to carrying PVL-positive gene (36.4% vs 14.3%, P=0.028). In summary, the molecular types of MRSA were getting complex over time. ST5-II-t311 was the predominant clone of MRSA isolate with a downward incidence from 2014 to 2018. ST59 MRSA strains, which is thought community related strain are spreading into hospitals and has an upward incidence from 2014 to 2018.

Methicillin-Resistant Staphylococcus aureus Bloodstream Infections in Hospitalized Patients in Peru.

There is a knowledge gap in the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) causing bloodstream infections (BSIs) in Peru. Through a surveillance study in 13 hospitals of 10 Peruvian regions (2017-2019), we assessed the proportion of MRSA among S. aureus BSIs as well as the molecular typing of the isolates. A total of 166 S. aureus isolates were collected, and 36.1% of them were MRSA. Of note, MRSA isolates with phenotypic and genetic characteristics of the hospital-associated Chilean-Cordobes clone (multidrug-resistant SCCmec I, non-Panton-Valentine leukocidin [PVL] producers) were most commonly found (70%), five isolates with genetic characteristics of community-associated MRSA (CA-MRSA)-SCCmec IV, PVL-producer-(8.3%) were seen in three separate regions. These results demonstrate that hospital-associated MRSA is the most frequent MRSA found in patients with BSIs in Peru. They also show the emergence of S. aureus with genetic characteristics of CA-MRSA. Further studies are needed to evaluate the extension of CA-MRSA dissemination in Peru.

Community-associated methicillin-resistant Staphylococcus aureus infection of diabetic foot ulcers in an eastern diabetic foot center in a tertiary hospital in China: a retrospective study

BackgroundDiabetic foot concerns are a major public health problem. Methicillin-resistant Staphylococcus aureus (MRSA) plays a significant role in diabetic foot ulcers. Community-associated MRSA has become notorious for skin and skin soft tissue infections over the last two decades. This study investigated MRSA infection in diabetic foot patients at a tertiary hospital, focusing on the epidemiology and characteristics of community-associated MRSA.MethodsA total of 149 patients with diabetic foot infection whose culture results indicated Staphylococcus aureus as the source were selected. Epidemiological investigations, clinical characteristics, laboratory index records, antibiotic susceptibility analysis, and clinical outcome tracking were performed in all cases. Based on oxacillin resistance using the Vitek Compact 2 system, cases were divided into methicillin-sensitive Staphylococcus aureus and MRSA groups. Subgroup analysis of the MRSA group was performed in accordance with the Centers for Disease Control definition: community-associated MRSA and hospital-associated MRSA.ResultsThe MRSA group (n = 41, 27.5%) had a longer duration of ulcers and hospital stay and higher hospitalization costs than the methicillin-sensitive Staphylococcus aureus group (n = 108, 72.5%). According to the classification criteria of Infectious Diseases Society of America, the severity of infection in the community-associated MRSA group was higher than that in the hospital-associated MRSA group. The analysis of antimicrobial susceptibility of 41 MRSA isolates showed that the resistance rates to erythromycin, clindamycin, quinolone, gentamicin, tetracycline, and rifampicin were 78.0%, 68.3%, 31.7%, 17.1%, 9.8%, and 2.4%, respectively. All the MRSA strains were sensitive to linezolid, tigecycline, and vancomycin. The resistance rates to quinolones and gentamycin in the community-associated MRSA group (both 0%) were lower than those in the hospital-associated MRSA group.ConclusionEmergence of MRSA in diabetic foot ulcer was associated with a prolonged wound duration and increased consumption of medical resources. Community-associated MRSA strains predominated among MRSA isolates from diabetic foot wounds and caused more severe infections.

Transmission of livestock-associated methicillin-resistant Staphylococcus aureus between animals, environment, and humans in the farm.

Staphylococcus aureus (S. aureus) is a fearsome bacterial pathogen that can colonize and infect humans and animals. Depending on the different sources, MRSA is classified as hospital-associated methicillin-resistant S. aureus (HA-MRSA), community-associated MRSA (CA-MRSA), and livestock-associated MRSA (LA-MRSA). LA-MRSA is initially associated with livestock, and clonal complexes (CCs) were almost always 398. However, the continued development of animal husbandry, globalization, and the widespread use of antibiotics have increased the spread of LA-MRSA among humans, livestock, and the environment, and other clonal complexes such as CC9, CC5, and CC8 have gradually emerged in various countries. This may be due to frequent host switching between humans and animals, as well as between animals. Host-switching is typically followed by subsequent adaptation through acquisition and/or loss of mobile genetic elements (MGEs) such as phages, pathogenicity islands, and plasmids as well as further host-specific mutations allowing it to expand into new host populations. This review aimed to provide an overview of the transmission characteristics of S. aureus in humans, animals, and farm environments, and also to describe the main prevalent clones of LA-MRSA and the changes in MGEs during host switching.

Modeling methicillin-resistant Staphylococcus aureus (MRSA) acquisitions in the intensive care unit with different staffing levels and finite direct-care tasks

Background: Modeling is a cost-effective way to evaluate interventions pertaining to hospital infection acquisitions, such as staffing levels. Increasing the number of nurses in an intensive care unit affects rates of HAI transmission. The way compartmental models are often formulated assumes that there is a never-ending series of tasks for workers to perform. Our previous models used a baseline of 1:3 nurse:patient ratio, and we kept the number of tasks the same across staffing ratios. We wanted to understand how having a finite number of tasks, using this baseline number, across staffing levels affected HAI acquisitions. Methods: We used a stochastic mathematical model of methicillin-resistant Staphylococcus aureus (MRSA) to study the impact of changes in staffing and a finite pool of tasks on hospital-associated acquisitions. For a 15-bed intensive care unit (ICU), we have 1 intensivist, and we set the nurse:patient ratios at 1:1, 1:1.5, 1:2.5, 1:3, 1:5, and 1:7.5, to represent the extreme ends of staffing levels and more moderate values in line with critical care society guidelines. Each model was run 1,000 times. The outcome of each scenario is the median number of hospital-associated MRSA acquisitions in 1 year from those 1,000 runs. Results: Treating the 1:3 nurse:patient ratio as the baseline, with 45 MRSA acquisitions per year, increasing the number of nurses from 5 to 6 (moving to a 1:2.5 nurse:patient ratio) had a relative risk (RR) of 0.77, suggesting that a small change in nurse staffing levels might have an outsized impact on rates. More dramatic changes had correspondingly larger swings in MRSA acquisition rates, with 1:1 nurse:patient ratio scenarios having an RR of 0.17, and at the other extreme, a 1:7.5 nurse:patient ratio having an RR of 4.66. Comparing the infinite to finite models, the ratios with more nurses had lower acquisition rates, with decreases ranging from 20% to 50%. Ratios with fewer nurses in the ICU showed 100%–400% increases in the number of acquisitions. All results were statistically significant. Conclusions: As nurse:patient ratios go up, the burden of direct-care tasks fall on fewer people, which has a direct impact on HAI rates. Our model demonstrates this hypothesis. Therefore, appropriate staffing should be considered in infection control guidelines, and the cost of staffing should be weighed against its impact on infection prevention as well as other areas of patient care. In this study, we considered only the impact from changes in contact patterns emerging from different staffing levels. Further insights may exist when considering other outcomes that also accompany increased staffing.Disclosures: None

Phenotypic and genomic analysis of the hypervirulent ST22 methicillin-resistant Staphylococcus aureus in China.

ST22 MRSA (methicillin-resistant Staphylococcus aureus) strains are only sporadically reported in China. Through the phylogenetic reconstruction of 30 ST22 strains from China and 480 ST22 strains from global sources, we found that the global ST22 strains can be divided into three clades (I, II, and III). The China ST22 strains were found primarily in clade II (IIb and IIc) and also in clade III, indicating that the China ST22-MRSA clones have different origins. The China subclade IIb strains (SCCmec Vb-t309) may evolve from the native ST22 MSSA clone, while the China IIc strains may have spread from other countries. Subclade IIc (SCCmecIVa-t309) strains exhibited particularly strong lethality and invasiveness in Galleria mellonella infection and mouse skin abscess models in comparison to USA300 and other dominant China HA-MRSA (ST5 and ST239) or CA-MRSA (ST59) strains. This study described the emergence of a highly virulent ST22 MRSA subclade and improved our insight into the molecular epidemiology of ST22 strains in China. IMPORTANCE ST22 is a successful hospital-associated MRSA lineage which first appeared in the United Kingdom as EMRSA-15. At present, ST22 MRSA clones are spreading rapidly around the world and even replaced other dominant clones in some regions. We placed the Chinese ST22 in the worldwide phylogeny of ST22, demonstrating a distinctive molecular epidemiology and to our knowledge, this is the first time that a novel clade of ST22 has been found in China. Among the 15 ST22 MRSA strains belonging to the novel clade, 14 ST22 SCCmecIVa strains from different regions carried both pvl and tst and displayed significantly higher in vitro and in vivo virulence in comparison to other clade/subclade ST22 strains as well as other common China HA-MRSA or CA-MRSA strains. The further spread of this subclade of strains could pose a serious threat to the health system in China and other regions.

A Sequalae of Lineage Divergence in Staphylococcus aureus from Community-Acquired Patterns in Youth to Hospital-Associated Profiles in Seniors Implied Age-Specific Host-Selection from a Common Ancestor

The rapidly changing epidemiology of Staphylococcus aureus and evolution of strains with enhanced virulence is a significant issue in global healthcare. Hospital-associated methicillin-resistant S. aureus (HA-MRSA) lineages are being completely replaced by community-associated S. aureus (CA-MRSA) in many regions. Surveillance programs tracing the reservoirs and sources of infections are needed. Using molecular diagnostics, antibiograms, and patient demographics, we have examined the distributions of S. aureus in Ha'il hospitals. Out of 274 S. aureus isolates recovered from clinical specimens, 181 (66%, n = 181) were MRSA, some with HA-MRSA patterns across 26 antimicrobials with almost full resistances to all beta-lactams, while the majority were highly susceptible to all non-beta-lactams, indicating the CA-MRSA type. The rest of isolates (34%, n = 93) were methicillin-susceptible, penicillin-resistant MSSA lineages (90%). The MRSA in men was over 56% among total MRSA (n = 181) isolates and 37% of overall isolates (n = 102 of 274) compared to MSSA in total isolates (17.5%, n = 48), respectively. However, these were 28.4% (n = 78) and 12.4% (n = 34) for MRSA and MSSA infections in women, respectively. MRSA rates per age groups of 0-20, 21-50, and >50 years of age were 15% (n = 42), 17% (n = 48), and 32% (n = 89), respectively. However, MSSA in the same age groups were 13% (n = 35), 9% (n = 25), and 8% (n = 22). Interestingly, MRSA increased proportional to age, while MSSA concomitantly decreased, implying dominance of the latter ancestors early in life and then gradual replacement by MRSA. The dominance and seriousness of MRSA despite enormous efforts in place is potentially for the increased use of beta-lactams known to enhance virulence. The Intriguing prevalence of the CA-MRSA patterns in young otherwise healthy individuals replaced by MRSA later in seniors and the dominance of penicillin-resistant MSSA phenotypes imply three types of host- and age-specific evolutionary lineages. Thus, the decreasing MSSA trend by age with concomitant increase and sub-clonal differentiation into HA-MRSA in seniors and CA-MRSA in young and otherwise healthy patients strongly support the notion of subclinal emergences from a resident penicillin-resistant MSSA ancestor. Future vertical studies should focus on the surveillance of invasive CA-MRSA rates and phenotypes.

Enhancing Antibiotics Efficacy by Combination of Kuraridin and Epicatechin Gallate with Antimicrobials against Methicillin-Resistant Staphylococcus aureus.

Staphylococcus aureus is an opportunistic pathogen and a major cause of nosocomial and community-acquired infections. The alarming rise in Methicillin-resistant S. aureus (MRSA) infection worldwide and the emergence of vancomycin-resistant MRSA strains have created an urgent need to identify new and alternative treatment options. Triple combinations of antimicrobials with different antimicrobial mechanisms may be a good choice to overcome antimicrobial resistance. In this study, we combine two natural compounds: kuraridin from Sophora flavescens and epicatechin gallate (ECG) from Camellia sinensis (Green tea), which could provide the best synergy with antibiotics against a selected panel of laboratory MRSA with known resistant mechanisms and clinical community-associated (CA) and hospital-associated (HA) MRSA as well. The combined use of ECG and kuraridin was efficacious in inhibiting the growth of a panel of tested MRSA strains. The antibacterial activities of gentamicin, fusidic acid and vancomycin could be further enhanced by the addition of ECG and kuraridin. In time-kill study, when vancomycin (0.5 μg/mL) was combined with ECG (2 μg/mL) and kuraridin (2 μg/mL), a very strong bactericidal growth inhibition against 3 tested strains ATCC25923, MRSA ST30 and ST239 was observed from 2 to 24 h. ECG and kuraridin both possess anti-inflammatory activities in bacterial toxin-stimulated peripheral blood mononuclear cells by suppressing the production of inflammatory cytokines (IL-1β, IL-6 and TNFα) and are non-cytotoxic. In a murine pneumonia model infected with ATCC25923, MRSA ST30 or ST239, the combined use of ECG and kuraridin with vancomycin could significantly reduce bacterial counts. The present findings reveal the potential of ECG and kuraridin combination as a non-toxic herbal and antibiotics combination for MRSA treatment with antibacterial and anti-inflammatory activities.

Diversity and Dissemination of Methicillin-Resistant Staphylococcus aureus (MRSA) Genotypes in Southeast Asia.

Methicillin-resistant Staphylococcus aureus (MRSA) is a successful pathogen that has achieved global dissemination, with high prevalence rates in Southeast Asia. A huge diversity of clones has been reported in this region, with MRSA ST239 being the most successful lineage. Nonetheless, description of MRSA genotypes circulating in the Southeast Asia region has, until now, remained poorly compiled. In this review, we aim to provide a better understanding of the molecular epidemiology and distribution of MRSA clones in 11 Southeast Asian countries: Singapore, Malaysia, Thailand, Vietnam, Cambodia, Lao People's Democratic Republic (PDR), Myanmar, Philippines, Indonesia, Brunei Darussalam, and Timor-Leste. Notably, while archaic multidrug-resistant hospital-associated (HA) MRSAs, such as the ST239-III and ST241-III, were prominent in the region during earlier observations, these were then largely replaced by the more antibiotic-susceptible community-acquired (CA) MRSAs, such as ST22-IV and PVL-positive ST30-IV, in recent years after the turn of the century. Nonetheless, reports of livestock-associated (LA) MRSAs remain few in the region.

Molecular characterization and virulence gene profiling of methicillin-resistant Staphylococcus aureus associated with bloodstream infections in southern China.

Methicillin-resistant Staphylococcus aureus (MRSA) causes an enormous illness burden, including skin and soft tissue infections (SSTIs), pneumonia, bloodstream infections (BSI), and sepsis. BSI are associated with significant patient morbidity and mortality worldwide. However, limited information is available on MRSA-related BSI in China. This study aimed to investigate the molecular characterization of 77 MRSA isolates recovered from hospitalized patients with BSI between 2012 and 2020 at three first-class tertiary hospitals in southern China based on multilocus sequence typing (MLST), spa typing, and staphylococcal cassette chromosome mec (SCCmec) typing. Overall, 13 clonal complexes (CCs) were identified, with CC59 and CC5 being the largest clusters, indicating high genetic diversity among BSI-causing MRSA isolates. ST59 was the most prevalent MLST type (22.1%). ST5/ST764-MRSA SCCmec II was the predominant adult MRSA clone, whereas ST59-MRSA SCCmec IV was the most common pediatric MRSA clone. ST5-t2460, ST764-t1084, and ST59-t437 were the most common types of adult MRSA isolates, whereas ST59-t437 and ST59-t172 were the predominant types of children's MRSA isolates. ST59-SCCmec IV/V represented the most common clone among community acquired-MRSA isolates. ST5/ST764-SCCmec II was the most common type of hospital-associated MRSA isolate. The most prevalent toxin-encoding genes detected were hla, hld, icaA, and clfA (96.1-100%). Forty-three (100%, 43/43) isolates harbored more than 18 of the tested virulence genes in adults and eight virulence genes (23.5%, 8/34) in children. Virulence gene analysis revealed diversity among different clones: the positivity rates for the Panton-Valentine leukocidin (PVL) gene were 55.8 and 35.3% in adult and pediatric MRSA isolates, respectively; the genes seb-sei were present in all adult strains; seb-seg-sei-seo were present in all ST5, ST59, ST15, ST45, and ST22 adult strains; and seg-sei-sem-sen-seo were present in different clones, including ST15, ST45, and ST22 adult MRSA isolates and ST25, ST30, ST546, and ST72 children's MRSA isolates. Adult MRSA isolates had significantly higher antibiotic resistance rates and virulence gene prevalence than pediatric MRSA isolates. For 8 years, this study provided epidemiological data on the molecular characteristics and virulence genes in different groups of MRSA BSI in China. Our findings may provide critical information for a better understanding of MRSA BSI.

MRSA in Humans, Pets and Livestock in Portugal: Where We Came from and Where We Are Going.

Over the years, molecular typing of methicillin-resistant S. aureus (MRSA) has allowed for the identification of endemic MRSA strains and pathogenic strains. After reaching a peak of predominance in a given geographic region, MRSA strains are usually replaced by a new strain. This process is called clonal replacement and is observed worldwide. The worldwide spread of hospital-associated MRSA (HA-MRSA), community-associated MRSA (CA-MRSA) and livestock-associated MRSA (LA-MRSA) clones over the last few decades has allowed this microorganism to be currently considered a pandemic. In Portugal, most HA-MRSA infections are associated with EMRSA-15 (S22-IV), New York/Japan (ST5-II) and Iberian (ST247-I) clones. Regarding the strains found in the community, many of them are frequently associated with the hospital environment, namely the Pediatric, Brazilian and Iberian clones. On the other hand, a strain that is typically found in animals, MRSA clonal complex (CC) 398, has been described in humans as colonizing and causing infections. The ST398 clone is found across all animal species, particularly in farm animals where the economic impact of LA-MRSA infections can have disastrous consequences for industries. In contrast, the EMRSA-15 clone seems to be more related to companion animals. The objective of this review is to better understand the MRSA epidemiology because it is, undoubtedly, an important public health concern that requires more attention, in order to achieve an effective response in all sectors.

Alcohol-based Nasal Decolonization and Chlorhexidine Bathing to Reduce Methicillin-resistant Staphylococcus Aureus Hospital-acquired Infections in Critical Patients

<h3>Background</h3> Infections associated with multi-drug resistant organisms [MDRO] are difficult to treat due to antibiotic resistance, increased mortality, prolonged length of stay, and hospitalization costs. Patients severely immunocompromised, such as patients in the intensive care unit [ICU], are often at higher risk. The purpose of this pilot study was to evaluate the effectiveness of a universal decolonization protocol within the critical care population of a large academic medical facility. The approach utilized an alcohol-based nasal decolonization agent and chlorhexidine gluconate [CHG] bathing to reduce hospital-acquired laboratory identified (LabID) methicillin-resistant Staphylococcus aureus (MRSA) blood infections. <h3>Methods</h3> The pilot included admitted ICU patients meeting inclusion criteria from February 2021 to July 2021. Education and integration of orders occurred in January 2021. Patients received nasal decolonization twice daily, along with daily CHG bathing. LabID MRSA blood events were recorded in the National Healthcare Safety Network [NHSN]. Infections were tracked pre-and-post implementation to evaluate intervention effectiveness. Baseline data was collected from July 2020 to December 2020 from the NHSN database. <h3>Results</h3> There was a noted reduction of LabID MRSA hospital-associated infection [HAI] events, decreasing from eight events pre-implementation (July 2020 – December 2020) to three events post-implementation (February 2021-July 2021). While not deemed statistically significant for this short study period as indicated by a two-tailed t-test (p-value 0.19, CI 95% [-0.56,2.23]), the overall reduction in HAI should be considered relevant to patient outcomes and overall infection prevention considerations. <h3>Conclusions</h3> The use of decolonization protocols has consistently been associated with improved outcomes and reduction of MRSA infections within literature. Reduction of infection is crucial for patient safety and quality outcomes. This pilot study noted a 62.5% decrease in hospital-associated LabID MRSA infection events after implementation of an alcohol-based nasal decolonization agent in combination with CHG bathing for ICU patients. This is in alignment with other published studies.

Draft Genome Sequences of 27 Hospital-Associated Methicillin-Resistant Staphylococcus aureus Strains Isolated in Minnesota.

ABSTRACTInfections caused by hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) strains have higher morbidity and mortality rates and require longer hospital stays than do those caused by hospital-associated methicillin-sensitive Staphylococcus aureus strains. To gain insight into their genomic makeup, antimicrobial resistance, biofilm formation, and virulence potentials, here we present the draft whole-genome sequences of 27 HA-MRSA strains isolated in Minnesota.

Role of Bioaerosols on the Short-Distance Transmission of Multidrug-Resistant Methicillin-Resistant Staphylococcus aureus (MRSA) in a Chicken Farm Environment.

Methicillin-resistant Staphylococcus aureus (MRSA) is a dynamic and tenacious pathogenic bacterium which is prevalent in livestock farming environments. This study investigated the possibility of MRSA spread via bioaerosol transmission from an indoor chicken farm environment to outdoors downwind (up to 50 m). The concentration of total airborne bacteria colony formation units (CFUs) was decreased with increasing sampling distance ranging from 9.18 × 101 to 3.67 × 103 per air volume (m3). Among the 21 MRSA isolates, 15 were isolated from indoor chicken sheds and exposure square areas, whereas 6 were isolated from downwind bioaerosol samples. Molecular characterization revealed that all of them carried the staphylococcal cassette chromosome mec (SCCmec) VIII, and they were remarkably linked with the hospital-associated MRSA group. Spa typing analysis determined that all MRSA isolates belonged to spa type t002. Virulence analysis showed that 100% of total isolates possessed exfoliative toxin A (eta), whereas 38.09% and 23.80% strains carried exfoliative toxin B (etb) and enterotoxin A (entA). Additionally, all of these MRSA isolates carried multidrug resistance properties and showed their resistance against chloramphenicol, ciprofloxacin, clindamycin, tetracycline, and erythromycin. In addition, chi-squared statistical analysis displayed a significant distributional relationship of gene phenotypes between MRSA isolates from chicken farm indoor and downwind bioaerosol samples. The results of this study revealed that chicken farm indoor air might act as a hotspot of MRSA local community-level outbreak, wherein the short-distance dispersal of MRSA could be supported by bioaerosols.

Prevalence of Staphylococcus aureus and Staphylococcus sciuri Isolated from Apparently Healthy and Hospitalized Patients in Ekiti State, Nigeria

The emergence of microbial resistance to antibiotics on daily basis has become a major global challenge. The increasing prevalence of methicillin resistant Staphylococcus aureus (MRSA) infections among hospitalized and non-hospitalized patients due to emergence of unique community-associated strains has become a great problem in Nigeria in particular and the entire world in general. In this study, a total of four hundred (400) clinical specimens were collected from hospitalized patients at Ekiti State University Teaching Hospital (EKSUTH), Ado-Ekiti and Federal Teaching Hospital (FETHI), Ido-Ekiti and from apparently healthy individuals from both communities. Standard bacteriological procedures were employed to isolate and identify these organisms. Antibiotic susceptibility test was carried out using the modified Kirby Bauer disc diffusion method. Polymerase chain reaction (PCR) assay was used to identify S. aureus nuc gene, as well as mecA and aac resistance genes. Seventy seven (19.3%) S. aureus isolates were phenotypically identified; 43 (21.5%) hospital-associated (23 from EKSUTH and 20 from FETHI) and 34 (17.0%) community-associated (27 from Ado-Ekiti and 7 from Ido-Ekiti communities). No S. sciuri was phenotypically isolated in both locations. Fifty five (71.4 %) of the 77 S. aureus isolates were nuc gene positive, while 11 (20%) of the 55 isolates were mecA gene positive, implying that they were MRSA. Of the 11 isolates, 6 (19.4%) were hospital-associated MRSA while 5 (20.8 %) were community-associated MRSA. Phenotypic resistance of S. aureus to cefoxitin in the two locations ranged between 77.8 – 100%, but 80% of cefoxitin-resistant nuc gene positive S. aureus lacked mecA gene. S. aureus isolates exhibited high phenotypic resistance to tetracycline, erythromycin and fusidic acid but susceptible to clindamycin and gentamycin. The prevalence of clinical MRSA infection of 20% in this study is relatively high. However, there was 0% prevalence of S. sciuri colonization. Cefoxitin disc test demonstrated low specificity as a phenotypic marker of methicillin resistance.There is need to institute control measures for MRSA infections and colonization in this environment.

Does the removal of contact precautions for MRSA and VRE infected patients change health care-associated infection rate?: A systematic review and meta-analysis

Update existing meta-analysis to analyze if discontinuation of contact precautions (CPs) for Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin resistant Enterococcus (VRE) colonization or infection affects hospital-associated MRSA or VRE infection rates. We conducted a systematic review of 17 studies evaluating discontinuation of CPs for MRSA and VRE. Random-effects and fixed-effects models were used to determine the pooled risk ratios (RR) of preincidence hospital-associated infection rate to postincidence rate. Subgroup analysis was used to assess sources of heterogeneity. No significant difference between rates of hospital-associated MRSA infection before and after stopping the CPs was observed (RR, 0.84; 95% confidence internal [CI], 0.71-1.01; P = .06). An inverse association was observed between discontinuation of CPs and rates of hospital-associated VRE infection (RR, 0.82; 95% CI, 0.72-0.94; P = .005). A subgroup analysis of 6 studies that used chlorhexidine, showed no difference between rates of hospital-associated MRSA infection with discontinuation of CPs (RR, 0.83; 95% CI, 0.69-1.00; P = .05). In 5 studies that did not use chlorhexidine, there was no difference between rates of hospital-associated MRSA infection with discontinuation of CPs (RR, 1.02; 95% CI, 0.55-1.88; P= .95). There was no significant difference in rates of hospital-associated MRSA infection before and after removing CPs. Additionally, there were decreased rates of hospital-associated VRE infection following stoppage of CPs.

PathoSPOT genomic epidemiology reveals under-the-radar nosocomial outbreaks

BackgroundWhole-genome sequencing (WGS) is increasingly used to map the spread of bacterial and viral pathogens in nosocomial settings. A limiting factor for more widespread adoption of WGS for hospital infection prevention practices is the availability of standardized tools for genomic epidemiology.MethodsWe developed the Pathogen Sequencing Phylogenomic Outbreak Toolkit (PathoSPOT) to automate integration of genomic and medical record data for rapid detection and tracing of nosocomial outbreaks. To demonstrate its capabilities, we applied PathoSPOT to complete genome surveillance data of 197 MRSA bacteremia cases from two hospitals during a 2-year period.ResultsPathoSPOT identified 8 clonal clusters encompassing 33 patients (16.8% of cases), none of which had been recognized by standard practices. The largest cluster corresponded to a prolonged outbreak of a hospital-associated MRSA clone among 16 adults, spanning 9 wards over a period of 21 months. Analysis of precise timeline and location data with our toolkit suggested that an initial exposure event in a single ward led to infection and long-term colonization of multiple patients, followed by transmissions to other patients during recurrent hospitalizations.ConclusionsWe demonstrate that PathoSPOT genomic surveillance enables the detection of complex transmission chains that are not readily apparent from epidemiological data and that contribute significantly to morbidity and mortality, enabling more effective intervention strategies.

Changing Epidemiology of Presumptive Community-associated-methicillin-resistant Staphylococcus Aureus in Slovenia in 2014-2015 Compared To 2010.

IntroductionAlthough the distinction between the Community-Associated-Methicillin-Resistant Staphylococcus aureus (CA-MRSA) and Hospital-Associated-Methicillin-Resistant S. aureus (HA-MRSA) has blurred in recent years, the CA-MRSA is an important group because of its potential to cause fulminant and severe infections. Its importance has further increased with the emergence of Livestock-Associated-Methicillin-Resistant S. aureus (LA-MRSA).MethodsIn the present study we analysed clonal distributions and virulence factors in presumptive CA-MRSA isolated from January 2014 to December 2015 and compared the results with our previous study from 2010. Phenotypic definition for presumptive CA-MRSA was based on resistance to cefoxitin and oxacillin and susceptibility to at least two of the following four antibiotics: ciprofloxacin, erythromycin, clindamycin and gentamicin.ResultsIn 2014 and 2015 altogether 304 MRSA isolates fulfilled our screening phenotypic definition, 45 isolates were cultivated from clinical specimens and 259 from screening specimens. Sequence types ST398, LA-MRSA and mecC MRSA increased significantly in 2015 compared to 2010 (p-value <0.05) and were spread over Slovenia.ConclusionThe clonal distribution of presumptive CA-MRSA has changed within the study period in Slovenia. In 2015 the most frequent clone among clinical and screening specimens was a pig-associated clone, ST398, but the number of confirmed ST398 infections remains low. While previously ST398 and mecC positive MRSA strains were geographically limited, they have spread throughout the country since 2010.

Emergence of livestock-associated MRSA ST398 from bulk tank milk, China.

To detect livestock-associated MRSA (LA-MRSA) ST398 from bulk tank milk in China and to determine the phenotypic and genomic characteristics of the strains. LA-MRSA ST398 strains were isolated from bulk tank milk samples in Shanghai and their susceptibilities to antimicrobials were determined using the broth dilution method. Genomic characterization of MRSA ST398 strains was performed by WGS and their evolutionary relationships were assessed by phylogenetic analysis. Two LA-MRSA ST398 isolates were recovered from bulk tank milk samples in two geographically distant farms in China. Whole-genome analysis strongly suggested that the LA-MRSA ST398 strains were closely related to the highly virulent hospital-associated MRSA (HA-MRSA) ST398 strains in China. The presence of LA-MRSA ST398 in bulk tank milk might be a serious threat to public health, highlighting the need for active surveillance of LA-MRSA in healthy cattle in China.