Seasonality of MRSA infections

Contrasting seasonality of the incidence of incisional surgical site infection after general and gastroenterological surgery: an analysis of 8436 patients in a single institute

BACKGROUND

While seasonality of hospital-acquired infections, including incisional SSI after orthopaedic surgery, is recognized, the seasonality of incisional SSI after general and gastroenterological surgeries remains unclear.

AIM

To analyse the seasonality and risk factors of incisional SSI after general and gastroenterological surgeries.

METHODS

This was a retrospective, single-institute, observational study using univariate and multivariate analyses. The evaluated variables included age, sex, surgical approach, surgical urgency, operation time, wound classification, and the American Society of Anesthesiologists physical status (ASA-PS).

FINDINGS

A total of 8436 patients were enrolled. General surgeries (N = 2241) showed a pronounced SSI incidence in summer (3.9%; odds ratio (OR): 1.87; 95% confidence interval (CI): 1.05-3.27; P = 0.025) compared to other seasons (2.1%). Conversely, gastroenterological surgeries (N = 6195) showed a higher incidence in winter (8.3%; OR: 1.38; 95% CI: 1.10-1.73; P = 0.005) than in other seasons (6.1%). Summer for general surgery (OR: 1.90; 95% CI: 1.12-3.24; P = 0.018) and winter for gastroenterological surgery (1.46; 1.17-1.82; P = 0.001) emerged as independent risk factors for incisional SSI. Open surgery (OR: 2.72; 95% CI: 1.73-4.29; P < 0.001) and an ASA-PS score ≥3 (1.64; 1.08-2.50; P = 0.021) were independent risk factors for incisional SSI in patients undergoing gastroenterological surgery during winter.

CONCLUSION

Seasonality exists in the incisional SSI incidence following general and gastroenterological surgeries. Recognizing these trends may help enhance preventive strategies, highlighting the elevated risk in summer for general surgery and in winter for gastroenterological surgery.

Seasonal variation and preoperative risk factors for polymicrobial infection following open fracture

Introduction

Despite modern approaches to open fracture management, fracture-related infection (FRI) rates remain high. Recent studies demonstrated the seasonal and regional variation of causative organisms in FRI. This study aims to better understand the causative organisms and identify preoperative risk factors for the primary outcome of FRIs at a Level I trauma center.

Materials and methods

This retrospective cohort study examined all patients that underwent irrigation and debridement of an open fracture at a single Level I trauma center between 2007 and 2019. Exclusion criteria included gunshot wounds, hand injuries, and follow-up less than 3 months. Patients that developed FRI were compared by season, injury characteristics, patient demographics, initial management, and causative organisms.

Results

Among 695 patients with open fractures, 78 patients (11.2 %) developed infection, of which eight were Gustilo-Anderson (GA) Type I, 16 were GA Type II, 25 were GA Type IIIA, 26 were GA Type IIIB, and three were GA Type IIIC. Gram-positive FRIs were most common (81.1 %), followed by 56.8 % polymicrobial, 54.1 % gram-negative, and 10.1 % culture-negative infections. More than half (55.1 %) of the infections were from open tibial fractures and occurred after a motorcycle (32.1 %) or motor vehicle collision (23.1 %). Patients were more likely to have high FRI rates in the summer (12.8 %, n = 29) and fall (15.8 %, n = 32) in comparison of spring (4.7 %, n = 7) and winter (8.5 %, n = 10) (p < 0.01). Staphylococcus infections were more common in fall and winter (73.8 %, n = 31) versus spring and summer (44.4 %, n = 16) (p = 0.01). Patients that were transferred from outside hospitals had significantly higher rates of polymicrobial infection when compared to those who arrived from the field (63.6 % vs 41.2 %, p = 0.03). No differences were observed in infection causative organisms based on GA type.

Conclusions

Two preoperative risk factors for polymicrobial infection following open fracture include inter-hospital transfers and warm/humid weather. Broadening antibiotic prophylaxis during spring/summer months or for transferred patients may enhance antibiotic coverage and reduce infections.

The Microbial Diversity and Antimicrobial Susceptibility Profile Underlying Diabetic Foot Osteomyelitis: A Retrospective Study Conducted in North Queensland, Australia

Background

Diabetic foot osteomyelitis (DFO) commonly occurs secondary to ulcerations of the skin. Empirical antibiotic agents are a key element of treatment and their use is dependent on local knowledge of the microbial spectrum of diabetic foot infections. This study aimed to retrospectively analyze the local microbiological profile, including bacterial culture/sensitivity results of DFO, and compare findings with literature. This study also aimed to review the concordance of microbiology results with national guidelines for the future treatment of DFO.

Methods

A retrospective review of clinical records was performed on patients who presented to the high-risk foot clinic, Townsville University Hospital, between 2018 and 2022. All patients older than 18 years and diagnosed with DFO were included. Our exclusion criteria included all other foot presentations, including trauma, vasculitis, and neoplasms.

Results

On the basis of the inclusion and exclusion criteria, 124 patients with DFO were selected. Most patients in the cohort were males (70.2%), non-Indigenous (68.5%), aged 50-69 years (55.6%), and with elevated HbA1c levels (>8.6). Chronic kidney disease (39.5%) and ischemic heart disease (41.9%) were common comorbidities. Of the pertinent microbial results, Staphylococcus aureus (~76%) was the most commonly isolated Gram-positive organism. Gram-positive bacteria were significantly increased in the elderly population with DFO (P < .05). All methicillin-resistant S aureus isolates were vancomycin- and cotrimoxazole-sensitive. Pseudomonas aeruginosa was the predominant Gram-negative organism isolated (39.3%). P aeruginosa exhibited low sensitivity to ciprofloxacin.

Conclusion

This study has enhanced our understanding of the various microbial species underlying DFO at our center and may be generalizable.

Level of Evidence

Level IV, retrospective case series.

Community methicillin-resistant Staphylococcus aureus outbreaks in areas of low prevalence

BACKGROUND

Community-acquired (CA), community-onset methicillin-resistant Staphylococcus aureus (CO-MRSA) infection presents a significant public health challenge, even where MRSA rates are historically lower. Despite successes in reducing hospital-onset MRSA, CO-MRSA rates are increasing globally, with a need to understand this trend, and the potential risk factors for re-emergence.

OBJECTIVES

This review aims to explore the characteristics of outbreaks of community-acquired community-onset methicillin-resistant Staphylococcus aureus in low-prevalence areas, to understand the factors involved in its rise, and to translate this knowledge into public health policy and further research needs.

SOURCES

PubMed, EMBASE, and Google Scholar were searched using combinations of the terms 'transmission', 'acquisition', 'community-acquired', 'MRSA', 'CA-MRSA', 'low prevalence', 'genomic', 'outbreak', 'colonisation', and 'carriage'. Wherever evidence was limited, additional articles were sought specifically, via PubMed searches. Papers where materials were not available in English were excluded.

CONTENT

Challenges in defining low-prevalence areas and the significance of exposure to various risk factors for community acquisition, such as healthcare settings, travel, livestock, and environmental factors, are discussed. The importance of genomic surveillance in identifying outbreak strains and understanding the transmission dynamics is highlighted, along with the need for robust public health policies and control measures.

IMPLICATIONS

The findings emphasise the complexity of CO-MRSA transmission and the necessity of a multifaceted approach in low-prevalence areas. This includes integrated and systematic surveillance of hospital-onset-, CO-, and livestock-associated MRSA, as has been effective in some Northern European countries. The evolution of CO-MRSA underscores the need for global collaboration, routine genomic surveillance, and comprehensive antimicrobial stewardship to mitigate the rise of CO-MRSA and address the broader challenge of antimicrobial resistance. These efforts are crucial for maintaining low MRSA prevalence and managing the increasing burden of CO-MRSA in both low and higher prevalence regions.

Temporal Cluster Analysis of Deep Sternal Wound Infection in a Regional Quality Collaborative

INTRODUCTION

Deep sternal wound infection (DSWI) is a rare complication associated with high mortality. Seasonal variability in surgical site infections has been demonstrated, however, these patterns have not been applied to DSWI. The purpose of this study was to assess temporal clustering of DSWIs.

METHODS

All cardiac surgery patients who underwent sternotomy were queried from a regional Society of Thoracic Surgeons database from 17 centers from 2001 to 2019. All patients with the diagnosis of DSWI were then identified. Cluster analysis was performed at varying time intervals (monthly, quarterly, and yearly) at the hospital and regional level. DSWI rates were calculated by year and month, and compared using mixed-effects negative binomial regression.

RESULTS

A total of 134,959 patients underwent a sternotomy for cardiac surgery, of whom 469 (0.35%) developed a DSWI. Rates of DSWI per hospital across all years ranged from 0.12% to 0.69%. Collaborative-level rates of DSWIs were the greatest in September (0.44%) and the lowest in January (0.30%). Temporal clustering was not seen across seasonal quarters (high rate in preceeding quarter was not associated with a high rate in the next quarter) (P = 0.39). There were yearly differences across all institutions in the DSWI rates. A downward trend in DSWI rates was seen from 2001 to 2019 (P < 0.001). A difference among hospitals in the cohort was observed (P < 0.001).

CONCLUSIONS

DSWI are a rare event within our region. Unlike other surgical site infection, there does not appear to be a seasonal pattern associated with DSWI.

Influence of environmental temperature and heatwaves on surgical site infection after hip and knee arthroplasty: a nationwide study

BACKGROUND

Previous studies reported higher incidence of surgical site infection (SSI) after procedures performed in summer or with high temperatures. However, no study used detailed climate data to assess this risk after hip and knee arthroplasty, and no study specifically investigated the role of heatwaves.

AIM

To assess the impact of higher environmental temperatures and heatwaves on SSI rates after hip and knee arthroplasty.

METHODS

Data on hip and knee arthroplasty procedures performed between 01/2013 - 09/2019 in hospitals participating in the Swiss SSI surveillance were linked to climate data extracted from weather stations located in their vicinity. The association between temperature, heatwaves and SSI was studied using mixed effects logistic regression models fitted at the patient level. Poisson mixed models were fitted for both calendar year and month of the year to investigate the SSI incidence trajectory over time.

RESULTS

We included 116,981 procedures performed in 122 hospitals. Significantly higher SSI rates were observed for procedures performed in the summertime (incidence rate ratio 1.39, 95% CI [1.20-1.60], p<0.001; reference: autumn) or in calendar months in which the mean temperature was above 20°C (reference 05-10°C; odds ratio 1.59, 95% CI [1.27, 1.98] p<0.001). We observed a slight but non-significant increase in the rate of SSI during heatwaves (1.44% versus 1.01%, p=0.2).

CONCLUSION

SSI rates after hip and knee replacement appear to increase with higher environmental temperature. To establish if, and to what extent, heatwaves increase the risk of SSI, studies involving geographical areas with larger variability in temperature are needed.

Double-swab 5% versus single-swab 10% iodophor for reducing methicillin-resistant Staphylococcus aureus with routine chlorhexidine bathing

In a prospective cohort study, we compared a 2-swabs-per-nostril 5% iodophor regimen with a 1-swab-per-nostril 10% iodophor regimen on methicillin-resistant Staphylococcus aureus carriage in nursing-home residents. Compared with baseline, both single-swab and double-swab regimens resulted in an identical 40% reduction in nasal carriage and 60% reduction in any carriage, skin or nasal.

Antibiotics Shift the Temperature Response Curve of Escherichia coli Growth

Temperature variation-through time and across climatic gradients-affects individuals, populations, and communities. Yet how the thermal response of biological systems is altered by environmental stressors is poorly understood. Here, we quantify two key features-optimal temperature and temperature breadth-to investigate how temperature responses vary in the presence of antibiotics. We use high-throughput screening to measure growth of Escherichia coli under single and pairwise combinations of 12 antibiotics across seven temperatures that range from 22°C to 46°C. We find that antibiotic stress often results in considerable changes in the optimal temperature for growth and a narrower temperature breadth. The direction of the optimal temperature shifts can be explained by the similarities between antibiotic-induced and temperature-induced damage to the physiology of the bacterium. We also find that the effects of pairs of stressors in the temperature response can often be explained by just one antibiotic out of the pair. Our study has implications for a general understanding of how ecological systems adapt and evolve to environmental changes. IMPORTANCE The growth of living organisms varies with temperature. This dependence is described by a temperature response curve that is described by an optimal temperature where growth is maximized and a temperature range (termed breadth) across which the organism can grow. Because an organism's temperature response evolves or acclimates to its environment, it is often assumed to change over only evolutionary or developmental timescales. Counter to this, we show here that antibiotics can quickly (over hours) change the optimal growth temperature and temperature breadth for the bacterium Escherichia coli. Moreover, our results suggest a shared-damage hypothesis: when an antibiotic damages similar cellular components as hot (or cold) temperatures do, this shared damage will combine and compound to more greatly reduce growth when that antibiotic is administered at hot (or cold) temperatures. This hypothesis could potentially also explain how temperature responses are modified by stressors other than antibiotics.

Seasonal impact on surgical site infections and wound healing disturbance in carpal tunnel surgery: A retrospective cohort study

Carpal tunnel syndrome is the most common entrapment syndrome of a peripheral nerve. The gold standard treatment is open carpal tunnel release which has a high success rate, a low complication rate, and predictable postoperative results. However, it has not been analysed yet if there is a seasonal influence on complications for carpal tunnel release, a highly elective procedure. In this retrospective study, we determine whether there is a seasonal impact on surgical site infections (SSI) and wound healing disorders (WHD) in primary carpal tunnel syndrome surgery. Between 2014 and 2018, we have assessed 1385 patients (65% female, 35% male) at a mean age of 61.9 (SD 15.3) years, which underwent open carpal tunnel release because of primary carpal tunnel syndrome. The seasonal data such as the warm season (defined as the period from 1st of June until 15th of September), the average daily and monthly temperature, and the average relative humidity were analysed. Patient demographics were examined including body mass index, alcohol and nicotine abuse, the use of anticoagulants and antiplatelet drugs as well as comorbidities. These data were correlated regarding their influence to the rate of surgical site infections and wound healing disorders in our study collective. A postoperative SSI rate of 2.4% and a WHD rate of 7% were detected. Our data confirms the warm season, the average monthly temperature, and male sex as risk factors for increasing rates of WHDs. Serious SSIs with subsequent revision surgery could be correlated with higher age and higher relative humidity. However there is no seasonal impact on SSIs. We therefore advise considering the timing of this elective surgery with scheduling older male patients preferably during the cold season to prevent postoperative WHDs.

Seasonal impact on surgical site infections in hip fracture surgery: Analysis of 330,803 cases using a nationwide inpatient database

BACKGROUND

As the aging population progresses, the number of elderly hip fracture patients is increasing. Elderly patients with hip fractures have a high risk of perioperative complications. One of the major complications after surgery is surgical site infection (SSI), which requires additional surgical interventions and is associated with increased mortality. Previous literature has shown that the risk of SSI is higher during the summer season in orthopedic surgery. However, little is known about the seasonal differences in the risk of SSI after hip fracture surgery. In this study, we aimed to identify the association between seasonality and SSI.

METHODS

We enrolled a total of 330,803 patients undergoing hip fracture surgery (65 years or older) using the Japanese Diagnosis Procedure Combination database. The study period was from April 1, 2011, to March 31, 2016. The data were analyzed to determine the association between seasonality and the incidence of SSI, debridement procedure. The primary outcome was the incidence of SSI and debridement. Other risk factors of SSI and debridement were investigated including seasons and confounders such as sex, age, BMI, smoking status, anticoagulant intake, comorbidities, surgical procedure based on medical diagnosis, waiting times for the surgery, and hospital surgical volume based on the previous literature, the risk of SSI and debridement.

RESULTS

Hip fracture surgeries performed in summer showed the highest risk for SSI and debridement. The risk for SSI was significantly associated with spring, and summer compared to winter (odds ratio [OR], 1.18; p, 0.016; OR, 1.19; p, 0.012, respectively). The incidence of debridement procedures after the initial surgery was also associated with spring, summer, and fall: the risk was the highest in summer (OR, 1.34; p, <0.001). Obesity, smoking history, number of comorbidities, anticoagulant intake before surgery, longer waiting time for surgery, and small hospital surgical volume were significantly associated with the risk of SSI.

CONCLUSIONS

We found a significant association between SSI after surgery for hip fractures and seasonality. Surgeries performed in summer had the highest risk for SSI and subsequent debridement procedures.

Epidemiology, Disposition, and Treatment of Ambulatory Veterans With Skin and Soft Tissue Infections

BACKGROUND

Most skin and soft tissue infections (SSTIs) are managed in the outpatient setting, but data are lacking on treatment patterns outside the emergency department (ED). Available data suggest that there is poor adherence to SSTI treatment guidelines.

METHODS

We conducted a retrospective cohort study of Veterans diagnosed with SSTIs in the ED or outpatient clinics from 1 January 2005 through 30 June 2018. The incidence of SSTIs over time was modeled using Poisson regression using robust standard errors. Antibiotic selection and incision and drainage (I&D) were described and compared between ambulatory settings. Anti-methicillin-resistant Staphylococcus aureus (MRSA) antibiotic use was compared to SSTI treatment guidelines.

RESULTS

There were 1 740 992 incident SSTIs in 1 156 725 patients during the study period. The incidence of SSTIs significantly decreased from 4.58 per 1000 patient-years in 2005 to 3.27 per 1000 patient-years in 2018 (P < .001). There were lower rates of β-lactam prescribing (32.5% vs 51.7%) in the ED compared to primary care (PC), and higher rates of anti-MRSA therapy (51.4% vs 35.1%) in the ED compared to PC. The I&D rate in the ED was 8.1% compared to 2.6% in PC. Antibiotic regimens without MRSA activity were prescribed in 24.9% of purulent SSTIs. Anti-MRSA antibiotics were prescribed in 40.1% of nonpurulent SSTIs.

CONCLUSIONS

We found a decrease in the incidence of SSTIs in the outpatient setting over time. Treatment of SSTIs varied depending on the presenting ambulatory location. There is poor adherence to guidelines in regard to use of anti-MRSA therapies. Further study is needed to understand the impact of guideline nonadherence on patient outcomes.

Antibiotic Resistance Pattern of Staphylococcus Aureus Isolated From Pediatrics With Ocular Infections: A 6-Year Hospital-Based Study in China

Staphylococcus aureus (S. aureus) is an important pathogen of ocular infections in pediatrics. The study aimed to identify the prevalence and resistance pattern of S. aureus, especially methicillin-resistant S. aureus (MRSA), in Chinese children with ocular infections. All patients with S. aureus infections were reviewed at a tertiary children's hospital during 2015-2020, and those with ocular infections were investigated for susceptibility results. Of 1,668 S. aureus strains, there were 177 unique isolates from ocular infection. Among them, 45 (25.4%) were MRSA and 132 (74.6%) were methicillin-sensitive S. aureus (MSSA). The proportion of MRSA did not change over time. Most of the strains were obtained from the neonate ward and ophthalmology department (n = 88, 49.7%, and n = 85, 48.0%, respectively), while eye secretion and pus were the main specimen types (n = 128, 72.3%, and n = 37, 20.9%, respectively). MRSA was significantly resistant against penicillin class (97.8%), erythromycin (71.1%), clindamycin (71.1%), and tetracycline (32.1%), with a high multidrug resistance (MDR) rate of 71.1%. However, MRSA was highly sensitive to levofloxacin. Resistance rates against erythromycin and ciprofloxacin as well as MDR percentage all increased among MSSA in children above 1 year of age, ophthalmology department, and outpatient population and decreased in eye secretion specimen. The mean resistance percentage remained stable for MRSA and MSSA during the study period. The survey of ocular S. aureus pathogens in pediatrics and their antibiotic resistance patterns helps in clinical treatment. MRSA with many strains demonstrating MDR is highly prevalent in children with ocular infections in Southeast China. Levofloxacin is an effective topical antibiotic for ocular MRSA infection, while erythromycin has a high resistance rate. The antibiotic resistance patterns of MRSA and MSSA differs and varies by different stratifications. A cautious use of antibiotics should be considered.

The interrelationships between antimicrobial resistance, COVID-19, past, and future pandemics

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 was first reported in Wuhan, China in December 2019 and is associated with high levels of morbidity and mortality. Various types of bacterial and fungal infections occur in patients with COVID-19 with some resistant to antimicrobials that are associated with significantly worse outcomes and deaths. Besides, antimicrobial-resistant (AMR) co-infections are responsible for clinically significant mortality in past pandemics. There is evidence to suggest that factors such as the proliferation of adulterated antimicrobials in some developing countries, international travels, issues with healthcare financing, use/misuse by humans, and in agricultural production and climate change are determinants of AMR at various levels of society. These complex interrelated determinants intersect with AMR in current and past pandemics and could amplify the potential of a future antimicrobial resistance pandemic. Therefore, global concerted interventions targeted at all levels of society to reduce the use/misuse of antimicrobials and disrupt these multifaceted, interrelated, and interdependent factors are urgently needed. This paper leverages prior research to describe complex major determinants of antimicrobial resistance and provides fresh insights into possible intervention strategies to tackle antimicrobial resistance including in the current and future pandemics.

Health Disparities in Staphylococcus aureus Transmission and Carriage in a Border Region of the United States Based on Cultural Differences in Social Relationships: Protocol for a Survey Study

Background

Health care–associated Staphylococcus aureus infections are declining but remain common. Conversely, rates of community-associated infections have not decreased because of the inadequacy of public health mechanisms to control transmission in a community setting. Our long-term goal is to use risk-based information from empirical socio-cultural-biological evidence of carriage and transmission to inform intervention strategies that reduce S aureus transmission in the community. Broad differences in social interactions because of cultural affiliation, travel, and residency patterns may impact S aureus carriage and transmission, either as risk or as protective factors.

Objective

This study aims to (1) characterize S aureus carriage rates and compare circulating pathogen genotypes with those associated with disease isolated from local clinical specimens across resident groups and across Hispanic and non-Hispanic white ethnic groups and (2) evaluate social network relationships and social determinants of health-based risk factors for their impact on carriage and transmission of S aureus.

Methods

We combine sociocultural survey approaches to population health sampling with S aureus carriage and pathogen genomic analysis to infer transmission patterns. Whole genome sequences of S aureus from community and clinical sampling will be phylogenetically compared to determine if strains that cause disease (clinical samples) are representative of community genotypes. Phylogenetic comparisons of strains collected from participants within social groups can indicate possible transmission within the group. We can therefore combine transmission data with social determinants of health variables (socioeconomic status, health history, etc) and social network variables (both egocentric and relational) to determine the extent to which social relationships are associated with S aureus transmission.

Results

We conducted a first year pilot test and feasibility test of survey and biological data collection and analytic procedures based on the original funded design for this project (#NIH U54MD012388). That design resulted in survey data collection from 336 groups and 1337 individuals. The protocol, described below, is a revision based on data assessment, new findings for statistical power analyses, and refined data monitoring procedures.

Conclusions

This study is designed to evaluate ethnic-specific prevalence of S aureus carriage in a US border community. The study will also examine the extent to which kin and nonkin social relationships are concordant with carriage prevalence in social groups. Genetic analysis of S aureus strains will further distinguish putative transmission pathways across social relationship contexts and inform our understanding of the correspondence of S aureus reservoirs across clinical and community settings. Basic community-engaged nonprobabilistic sampling procedures provide a rigorous framework for completion of this 5-year study of the social and cultural parameters of S aureus carriage and transmission.

Seasonality of respiratory viruses and bacterial pathogens

Background

Seasonal variation has been observed for various bacterial and viral infections. We aimed to further study seasonality of respiratory viruses and bacterial pathogens in relation to antibiotic use, as well as meteorological parameters.

Methods

An ecologic study of antibiotic exposure, meteorological parameters, detection of respiratory viruses  and clinical isolates of Clostridioides difficile, Methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, and Escherichia coli and Klebsiella pneumoniae (grouped together as gram-negative bacteria; GNB) in Rhode Island from 2012 to 2016.

Results

Peak detection of C. difficile occurred 3 months after the peak in antibiotic prescriptions filled (OR = 1.24, 95% CI, 1.07–1.43; P = 0.006). Peak MRSA detection was noted 7 months after the peak in antibiotic prescriptions filled (OR = 1.69, 95% CI, 1.21–2.35; P = 0.003) and 10 months after the peak in respiratory virus detection (OR = 1.04, 95% CI, 1.01–1.06; P = 0.003). Peak GNB detection was noted 2 months after the peak mean monthly ambient temperature (OR = 1.69, 95% C.I., 1.20–2.39; P = 0.004). Peak detection of S. pneumoniae was noted at the same time as the peak in detection of respiratory viruses (OR = 1.01, 95% C.I., 1.00–1.01; P = 0.015).

Conclusions

We identified distinct seasonal variation in detection of respiratory viruses and bacterial pathogens. C. difficile seasonality may, in part, be related to antibiotic prescriptions filled; GNB seasonality may be related to ambient temperature and S. pneumoniae may be related to concurrent respiratory viral infections.

Electronic supplementary material

The online version of this article (10.1186/s13756-019-0574-7) contains supplementary material, which is available to authorized users.

Warmer Weather as a Risk Factor for Cellulitis: A Population-based Investigation

Background

The incidence of cellulitis is highly seasonal and this seasonality may be explained by changes in the weather, specifically, temperature.

Methods

Using data from the Nationwide Inpatient Sample (years 1998 to 2011), we identified the geographic location for 773719 admissions with the primary diagnosis (ICD-9-CM code) of cellulitis and abscess of finger and toe (681.XX) and other cellulitis and abscess (682.XX). Next, we used data from the National Climatic Data Center to estimate the monthly average temperature for each of these different locations. We modeled the odds of an admission having a primary diagnosis of cellulitis as a function of demographics, payer, location, patient severity, admission month, year, and the average temperature in the month of admission.

Results

We found that the odds of an admission with a primary diagnosis of cellulitis increase with higher temperatures in a dose-response fashion. For example, relative to a cold February with average temperatures under 40° F, an admission in a hot July with an average temperature exceeding 90°F has 66.63% higher odds of being diagnosed with cellulitis (95% confidence interval [CI]: [61.2, 72.3]). After controlling for temperature, the estimated amplitude of seasonality of cellulitis decreased by approximately 71%.

Conclusion

At a population level, admissions to the hospital for cellulitis risk are strongly associated with warmer weather.

Modeling the seasonality of Methicillin-resistant Staphylococcus aureus infections in hospitals with environmental contamination

A deterministic mathematical model with periodic antibiotic prescribing rate is constructed to study the seasonality of Methicillin-resistant Staphylococcus aureus (MRSA) infections taking antibiotic exposure and environmental contamination into consideration. The basic reproduction number R0 for the periodic model is calculated under the assumption that there are only uncolonized patients with antibiotic exposure at admission. Sensitivity analysis of R0 with respect to some essential parameters is performed. It is shown that the infection would go to extinction if the basic reproduction number is less than unity and would persist if it is greater than unity. Numerical simulations indicate that environmental cleaning is the most important intervention to control the infection, which emphasizes the effect of environmental contamination in MRSA infections. It is also important to highlight the importance of effective antimicrobial stewardship programmes, increase active screening at admission and subsequent isolation of positive cases, and treat patients quickly and efficiently.

Is Climate Associated With Revision for Prosthetic Joint Infection After Primary TKA?

BACKGROUND

Climate factors have been shown to be associated with spontaneous musculoskeletal and some surgical site infections with increased rates of infection during warmer periods. To date, little research has been performed to determine if this phenomenon is associated with differences in the risk of revision for prosthetic joint infection (PJI) in primary TKA.

QUESTIONS/PURPOSES

(1) Does the rate of revision for early PJI within the first year after primary TKA differ between tropical and nontropical regions? (2) Is there a seasonal variation in the rate of revision for PJI? (3) Is the geographic and seasonal variation (if present) associated with the sex, age, and/or American Society of Anesthesiologists (ASA) grade of the patient?

METHODS

All 219,983 primary TKAs performed for osteoarthritis over a 5-year period (2011-2015) in the Australian Orthopaedic Association National Joint Replacement Registry were examined based on the month of the primary procedure to determine the rate of revision for PJI within 12 months. The data were analyzed to determine the differences in the risk of revision for PJI based on geographic region and season of the primary procedure adjusting for sex, age, and ASA grade of the patient.

RESULTS

The early revision rate for PJI was higher in the tropical compared with the nontropical region of Australia (0.73% versus 0.37%; odds ratio [OR], 1.87; 95% confidence interval [CI], 1.44-2.42; p < 0.001). The tropical region of Australia demonstrated a seasonal variation in the rate of revision for PJI with a higher rate during the warmer monsoon wet season of summer and fall (summer/fall 0.98% versus winter/spring 0.51%; OR, 1.88; 95% CI, 1.12-3.16; p = 0.02). A seasonal variation was not seen in the nontropical region (OR, 1.03; 95% CI, 0.90-1.19; p = 0.64). The regional and seasonal changes were independent of sex, age, and ASA grade.

CONCLUSIONS

Climate factors are associated with the risk of early revision for PJI in patients undergoing primary TKA with rates of such revisions approximately double in tropical regions compared with nontropical regions. Additionally, tropical regions demonstrate a seasonal variation with the risk of PJI doubling during the warmer, monsoonal wet season of summer and fall. These findings should be confirmed in further studies that can better control for possible confounding variables. The mechanism for this phenomenon is not clear, and further research into this subject is also indicated.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Control of healthcare- and community-associated MRSA: recent progress and persisting challenges

BACKGROUND

Healthcare adapted meticillin-resistant Staphylococcus aureus (MRSA) has spread to hospitals around the world over 50 years. More recently, other strains of MRSA have emerged with the ability to spread in the community and infect otherwise healthy individuals. Morbidity and mortality associated with MRSA remains high and its control in both the healthcare and community setting has proven challenging.

SOURCES OF DATA

Pubmed (Medline).

AREAS OF AGREEMENT

The use of targeted screening and decolonization, hand hygiene and antimicrobial stewardship is supported by the most robust studies, though many studies have implemented bundles for effective healthcare-associated (HA)-MRSA control.

AREAS OF CONTENTION

Universal screening, universal decolonization and contact precautions for HA-MRSA control are supported by less evidence. Some interventions may not be cost-effective. Contact precautions may be associated with potential for patient harm. Evidence for effective control community acquired (CA)-MRSA is largely lacking.

GROWING POINTS

Programmes that focus on implementing bundles of interventions aimed at targeting HA-MRSA are more likely to be effective, with an emphasis on hand hygiene as a key component. Control of CA-MRSA is likely to be more difficult to achieve and relies on prevalence, risk factors and community healthcare interactions on a broader scale.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further research in the area of CA-MRSA in particular is required. Antimicrobial stewardship for both CA and HA-MRSA is promising, as is the role of whole genome sequencing in characterizing transmission. However, further work is required to assess their long-term roles in controlling MRSA. With many institutions applying widespread use of chlorhexidine washes, monitoring for chlorhexidine resistance is paramount to sustaining efforts at controlling MRSA.

Community-associated methicillin-resistant Staphylococcus aureus infections in Aboriginal children attending hospital emergency departments in a regional area of New South Wales, Australia: a seven-year descriptive study

Objective

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) can cause bacterial skin infections that are common problems for Aboriginal children in New South Wales (NSW). MRSA is not notifiable in NSW and surveillance data describing incidence and prevalence are not routinely collected. The study aims to describe the epidemiology of CA-MRSA in Aboriginal children in the Hunter New England Local Health District (HNELHD).

Methods

We linked data from Pathology North Laboratory Management System (AUSLAB) and the HNELHD patient administration system from 33 hospital emergency departments. Data from 2008–2014 for CA-MRSA isolates were extracted. Demographic characteristics included age, gender, Aboriginality, rurality and seasonality.

Results

Of the 1222 individuals in this study, 408 (33.4%) were Aboriginal people. Aboriginal people were younger with 45.8% aged less than 10 years compared to 25.9% of non-Aboriginal people. Most isolates came from Aboriginal people who attended the regional Tamworth Hospital (193/511 isolates from 149 people). A larger proportion of Aboriginal people, compared to non-Aboriginal people, resided in outer regional (64.9% vs 37.2%) or remote/very remote areas (2.5% vs 0.5%). Most infections occurred in summer and early autumn. For Aboriginal patients, there was a downward trend through autumn, continuing through winter and spring.

Discussion

Aboriginal people at HNELHD emergency departments appear to represent a greater proportion of people with skin infections with CA-MRSA than non-Aboriginal people. CA-MRSA is not notifiable in NSW; however, pathology and hospital data are available and can provide valuable indicative data to health districts for planning and policy development.

Methods for computational disease surveillance in infection prevention and control: Statistical process control versus Twitter's anomaly and breakout detection algorithms

BACKGROUND

Although not all health care-associated infections (HAIs) are preventable, reducing HAIs through targeted intervention is key to a successful infection prevention program. To identify areas in need of targeted intervention, robust statistical methods must be used when analyzing surveillance data. The objective of this study was to compare and contrast statistical process control (SPC) charts with Twitter's anomaly and breakout detection algorithms.

METHODS

SPC and anomaly/breakout detection (ABD) charts were created for vancomycin-resistant Enterococcus, Acinetobacter baumannii, catheter-associated urinary tract infection, and central line-associated bloodstream infection data.

RESULTS

Both SPC and ABD charts detected similar data points as anomalous/out of control on most charts. The vancomycin-resistant Enterococcus ABD chart detected an extra anomalous point that appeared to be higher than the same time period in prior years. Using a small subset of the central line-associated bloodstream infection data, the ABD chart was able to detect anomalies where the SPC chart was not.

DISCUSSION

SPC charts and ABD charts both performed well, although ABD charts appeared to work better in the context of seasonal variation and autocorrelation.

CONCLUSIONS

Because they account for common statistical issues in HAI data, ABD charts may be useful for practitioners for analysis of HAI surveillance data.

Hospital admissions for skin infections among Western Australian children and adolescents from 1996 to 2012

The objective of this study was to describe the occurrence of skin infection associated hospitalizations in children born in Western Australia (WA). We conducted a retrospective cohort study of all children born in WA between 1996 and 2012 (n = 469,589). Of these, 31,348 (6.7%) were Aboriginal and 240,237 (51.2%) were boys. We report the annual age-specific hospital admission rates by geographical location and diagnostic category. We applied log-linear regression modelling to analyse changes in temporal trends of hospitalizations. Hospitalization rates for skin infections in Aboriginal children (31.7/1000 child-years; 95% confidence interval [CI] 31.0–32.4) were 15.0 times higher (95% CI 14.5–15.5; P<0.001) than those of non-Aboriginal children (2.1/1000 child-years; 95% CI 2.0–2.1). Most admissions in Aboriginal children were due to abscess, cellulitis and scabies (84.3%), while impetigo and pyoderma were the predominant causes in non-Aboriginal children (97.7%). Admissions declined with age, with the highest rates for all skin infections observed in infants. Admissions increased with remoteness. Multiple admissions were more common in Aboriginal children. Excess admissions in Aboriginal children were observed during the wet season in the Kimberley and during summer in metropolitan areas. Our study findings show that skin infections are a significant cause of severe disease, requiring hospitalization in Western Australian children, with Aboriginal children at a particularly high risk. Improved community-level prevention of skin infections and the provision of effective primary care are crucial in reducing the burden of skin infection associated hospitalizations. The contribution of sociodemographic and environmental risk factors warrant further investigation.

Seasonal Variations in the Risk of Reoperation for Surgical Site Infection Following Elective Spinal Fusion Surgery: A Retrospective Study Using the Japanese Diagnosis Procedure Combination Database

STUDY DESIGN

A retrospective study of data abstracted from the Diagnosis Procedure Combination (DPC) database, a national representative database in Japan.

OBJECTIVE

The aim of this study was to examine seasonal variations in the risk of reoperation for surgical site infection (SSI) following spinal fusion surgery.

SUMMARY OF BACKGROUND DATA

Although higher rates of infection in the summer than in other seasons were thought to be caused by increasing inexperience of new staff, high temperature, and high humidity, no studies have examined seasonal variations in the risk of SSI following spinal fusion surgery in the country where medical staff rotation timing is not in summer season. In Japan, medical staff rotation starts in April.

METHODS

We retrospectively extracted the data of patients who were admitted between July 2010 and March 2013 from the DPC database. Patients were included if they were aged 20 years or older and underwent elective spinal fusion surgery. The primary outcome was reoperation for SSI during hospitalization. We performed multivariate analysis to clarify the risk factors of primary outcome with adjustment for patient background characteristics.

RESULTS

We identified 47,252 eligible patients (23,659 male, 23,593 female). The mean age of the patients was 65.4 years (range, 20-101 yrs). Overall, reoperation for SSI occurred in 0.93% of the patients during hospitalization. The risk of reoperation for SSI was significantly higher in April (vs. February; odds ratio, 1.93; 95% confidence interval, 1.09-3.43, P = 0.03) as well as other known risk factors. In subgroup analysis with stratification for type of hospital, month of surgery was identified as an independent risk factor of reoperation for SSI among cases in an academic hospital, although there was no seasonal variation among those in a nonacademic hospital.

CONCLUSION

This study showed that month of surgery is a risk factor of reoperation for SSI following elective spinal fusion surgery, nevertheless, in the country where medical staff rotation timing is not in summer season.

LEVEL OF EVIDENCE

3.

Seasonality of acquisition of respiratory bacterial pathogens in young children with cystic fibrosis

Background

Seasonal variations are often observed for respiratory tract infections; however, limited information is available regarding seasonal patterns of acquisition of common cystic fibrosis (CF)-related respiratory pathogens. We previously reported differential seasonal acquisition of Pseudomonas aeruginosa in young children with CF and no such variation for methicillin-susceptible Staphylococcus aureus acquisition. The purpose of this study was to describe and compare the seasonal incidence of acquisition of other respiratory bacterial pathogens in young children with CF.

Methods

We conducted a retrospective study to describe and compare the seasonal incidence of methicillin-resistant Staphylococcus aureus (MRSA), Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and Haemophilus influenzae acquisition in young CF patients residing in the U.S. using the Cystic Fibrosis Foundation National Patient Registry, 2003-2009. Log-linear overdispersed Poisson regression was used to evaluate seasonal acquisition of each of these pathogens.

Results

A total of 4552 children met inclusion criteria. During follow-up 910 (20%), 1161 (26%), 228 (5%), and 2148 (47%) children acquired MRSA, S. maltophilia, A. xylosoxidans and H. influenzae, respectively. Compared to winter season, MRSA was less frequently acquired in spring (Incidence Rate Ratio [IRR]: 0.79; 95% Confidence Interval [CI]: 0.65, 0.96) and summer (IRR: 0.69; 95% CI: 0.57, 0.84) seasons. Similarly, a lower rate of A. xylosoxidans acquisition was observed in spring (IRR: 0.59; 95% CI: 0.39, 0.89). For H. influenzae, summer (IRR: 0.88; 95% CI: 0.78, 0.99) and autumn (IRR: 0.78; 95% CI: 0.69, 0.88) seasons were associated with lower acquisition rates compared to winter. No seasonal variation was observed for S. maltophilia acquisition.

Conclusion

Acquisition of CF-related respiratory pathogens displays seasonal variation in young children with CF, with the highest rate of acquisition for most pathogens occurring in the winter. Investigation of factors underlying these observed associations may contribute to our understanding of the aetiology of these infections and guide future infection control strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2511-9) contains supplementary material, which is available to authorized users.

Discontinuation of contact precautions with the introduction of universal daily chlorhexidine bathing

Contact precautions are a traditional strategy to prevent transmission of methicillin-resistant Staphylococcus aureus (MRSA). Chlorhexidine bathing is increasingly used to decrease MRSA burden and transmission in intensive care units (ICUs). We sought to evaluate a hospital policy change from routine contact precautions for MRSA compared with universal chlorhexidine bathing, without contact precautions. We measured new MRSA acquisition in ICU patients and surveyed for MRSA environmental contamination in common areas and non-MRSA patient rooms before and after the policy change. During the baseline and chlorhexidine bathing periods, the number of patients (453 vs. 417), ICU days (1999 vs. 1703) and MRSA days/1000 ICU days (109 vs. 102) were similar. MRSA acquisition (2/453 vs. 2/457, P = 0·93) and environmental MRSA contamination (9/474 vs. 7/500, P = 0·53) were not significantly different between time periods. There were 58% fewer contact precaution days in the ICU during the chlorhexidine period (241/1993 vs. 102/1730, P < 0·01). We found no evidence that discontinuation of contact precautions for patients with MRSA in conjunction with adoption of daily chlorhexidine bathing in ICUs is associated with increased MRSA acquisition among ICU patients or increased MRSA contamination of ICU fomites. Although underpowered, our findings suggest this strategy, which has the potential to reduce costs and improve patient safety, should be assessed in similar but larger studies.

The Seasonal Variability in Surgical Site Infections and the Association With Warmer Weather: A Population-Based Investigation

OBJECTIVE To determine whether the seasonality of surgical site infections (SSIs) can be explained by changes in temperature. DESIGN Retrospective cohort analysis. SETTING The National Inpatient Sample database. PATIENTS All hospital discharges with a primary diagnosis of SSI from 1998 to 2011 were considered cases. Discharges with a primary or secondary diagnoses of specific surgeries commonly associated with SSIs from the previous and current month served as our "at risk" cohort. METHODS We modeled the national monthly count of SSI cases both nationally and stratified by region, sex, age, and type of institution. We used data from the National Climatic Data Center to estimate the monthly average temperatures for all hospital locations. We modeled the odds of having a primary diagnosis of SSI as a function of demographics, payer, location, patient severity, admission month, year, and the average temperature in the month of admission. RESULTS SSI incidence is highly seasonal, with the highest SSI incidence in August and the lowest in January. During the study period, there were 26.5% more cases in August than in January (95% CI, 23.3-29.7). Controlling for demographic and hospital-level characteristics, the odds of a primary SSI admission increased by roughly 2.1% per 2.8°C (5°F) increase in the average monthly temperature. Specifically, the highest temperature group, >32.2°C (>90°F), was associated with an increase in the odds of an SSI admission of 28.9% (95% CI, 20.2-38.3) compared to temperatures <4.4°C (<40°F). CONCLUSIONS At population level, SSI risk is highly seasonal and is associated with warmer weather. Infect Control Hosp Epidemiol 2017;38:809-816.

Prevalence and molecular characterization of Staphylococcus aureus in commercially available meat over a one-year period in Iowa, USA

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of infectious disease morbidity and mortality. Previous studies have confirmed the presence of S. aureus, including MRSA, on raw meat products. We investigated the prevalence and molecular epidemiology of S. aureus and MRSA in commercially-distributed antibiotic-free and conventional raw meat products (n = 3290) purchased in 8 Iowa retail stores weekly for a period of one year. Isolates were characterized using spa typing, and PCR was used to detect the presence of the Panton-Valentine leukocidin (PVL) and mecA genes. Quantitation of S. aureus on meat products was carried out one week per month. The prevalence of S. aureus on meat samples was 27.8% (913/3290). Compared to antibiotic-free meat samples, higher prevalence of both MRSA and methicillin-susceptible S. aureus (MSSA) were found in conventional meat samples. Among the S. aureus isolates, 18 were PVL-positive (1.9%) and 41 (4.5%) carried mecA. Phenotypic oxacillin resistance was observed for 17.1% (41/239) of the isolates tested, while 23% (55/239) were multi-drug resistant. A total of 132 spa types were detected from 913 contaminated meat samples. Overall, t002 was the most common spa type identified (137; 15.0%). The number of colony-forming units (CFU) per 10 g meat ranged from 2 to 517 (median: 8 CFU per 10 g of meat; mean: 28) with the highest bacterial load observed on turkey samples. These data reinforce the need to consider meat products as potential vehicles of S. aureus transmission from farm into human households, and the potential need for public health intervention programs pre and post-slaughter in meat processing facilities.

Increasing Incidence, Cost, and Seasonality in Patients Hospitalized for Cellulitis

Using data from the National Inpatient Sample, 1998-2013, we show that hospitalizations for cellulitis have approximately doubled. Costs increased by 118% to $3.74 billion annually. In addition, hospitalizations for cellulitis are highly seasonal, peaking in summer months: incidence during the peak month of July is 35% higher than in February.

Using Positive Deviance in the prevention and control of MRSA infections in a Colombian hospital: a time-series analysis

Positive Deviance (PD) is a process to achieve a social and cultural change. This strategy has been used for the control of methicillin-resistant Staphylococcus aureus (MRSA) infection in some health institutions in the United States, but has rarely been adopted in institutions from developing countries where resources are limited. We describe our experience of PD in the control of healthcare-associated infections (HAIs) due to MRSA in a Colombian hospital with the aim of reducing HAI rates through a cultural change in processes. A time-series study was conducted based on the MRSA-HAI rate and the number of months with zero MRSA infections before and after application of PD (2001-2012). On comparing the pre-intervention and intervention periods, the mean overall rates of MRSA-HAI was 0·62 and 0·36, respectively (P = 0·0005); the number of months with zero MRSA-HAIs were 3/70 and 12/74 (odds ratio 0·264, 95% confidence interval 0·078-0·897); the percentage of MRSA-HAIs was 53·2% and 41·0%. These results are consistent with other published data. Implementation of PD was associated with a significant reduction of MRSA-HAIs, it did not involve high costs and the changes have been lasting.

Decreasing Incidence of Skin and Soft Tissue Infections With a Seasonal Pattern at an Academic Medical Center, 2006-2014

The incidence of SSTIs at University of Chicago Medicine decreased significantly in children and adults with seasonal variation, peaking during the summer months. This suggests a reversal of the massive increase in SSTI incidence after 2000 in the U.S.

Background. The incidence of skin and soft tissue infections (SSTIs) in the United States increased sharply after 2000 with the emergence of USA300 methicillin-resistant Staphylococcus aureus. We examined trends in SSTI incidence in 2006–2014 at the University of Chicago Medicine (UCM).

Methods. Data were obtained for patient encounters at UCM with an International Classification of Diseases, Ninth Revision-coded SSTI diagnosis between January 1, 2006 and March 31, 2014. Incidence density was calculated per 1000 encounters by quarter and year. Encounters were stratified by inpatient, outpatient clinic and emergency department (ED) encounters and by age group, gender, and race. Poisson regression was used to assess change over time.

Results. In 2006–2014, data were collected for 38 201 SSTI-associated encounters among 31 869 subjects. Among all patients treated at UCM, there was a decrease of 1% per year in the incidence of SSTIs during 2006–2013, with an overall decrease of 16%. There was a significant decrease in SSTI-related encounters among inpatients (rate ratio [RR] = 0.97; 95% confidence interval [CI], .96–.98), ED patients (RR = 0.98; 95% CI, .97–.98), adults (RR = 0.98; 95% CI, .97–.98), children (RR = 0.96; 95% CI, .95–.97), and African Americans (RR = 0.99; 95% CI, .98–.99). There was an annual seasonal trend, with the peak incidence occurring during the late summer.

Conclusions. The incidence of SSTIs at UCM decreased in children and adults with seasonal variation, peaking during the summer months. This suggests a reversal of the massive increase in SSTI incidence in the United States after 2000.

Characteristics and risk factors of hospital acquired - Methicillin-resistant Staphylococcus aureus (HA-MRSA) infection of pediatric patients in a tertiary care hospital in Riyadh, Saudi Arabia

Background and objectives

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infections has been steadily increasing. These infections are considered to be either hospital-acquired MRSA (HA-MRSA) or community-acquired MRSA (CA-MRSA). Children are at higher risk of infection than adults. HA-MRSA has been reported to have more serious outcomes than CA-MRSA. However, there are not enough studies in Saudi Arabia to study the characteristics of HA-MRSA in children. We aim to describe the characteristics of HA-MRSA infection, including risk factors, culture site, clinical manifestations, complications, and outcomes among pediatric patients in a tertiary care hospital in Riyadh, Saudi Arabia.

Design and settings

This is a retrospective chart review study. It was conducted in King Abdulaziz medical city in Riyadh.

Patients and methods

The study included all patients 14 years of age or younger who were culture-positive from any site in the body during the period from January 1, 2009 to December 31, 2011. The time of culture compared to admission time was used to differentiate between CA-MRSA (within 72 h of admission) and HA-MRSA (more than 72 h after admission). The final sample size was 39 patients.

Results

We found HA-MRSA to be more common in males and those with risk factors such as previous surgery and previous hospitalization. Patients had a high Pediatric intensive care unit (PICU) admission rate and were commonly septic with positive blood cultures. Seventy-four percent of patients fully recovered, 10% recovered with complications and 15% died.

Conclusion

HA-MRSA is an infection that can cause serious complications and a high rate of PICU admissions. Clinical manifestations such as shock are associated with higher mortality and morbidity rates. Special care should be given to those admitted to PICU, as they have high rates of mortality and morbidity.

Latitude of the study place and age of the patient are associated with incidence of mediastinitis and microbiology in open-heart surgery: a systematic review and meta-analysis

Objective

We aimed to summarize the pooled frequency of mediastinitis following open-heart surgery caused by Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), and Gram-negative bacteria.

Design

This study was a systematic review and a meta-analysis of prospective and retrospective cohort studies.

Materials and methods

We searched the literature, and a total of 97 cohort studies were identified. Random-effect model was used to synthesize the results. Heterogeneity between studies was examined by subgroup and meta-regression analyses, considering study and patient-level variables. Small-study effect was evaluated.

Results

Substantial heterogeneity was present. The estimated incidence of mediastinitis evaluated from 97 studies was 1.58% (95% confidence intervals [CI] 1.42, 1.75) and that of Gram-positive bacteria, Gram-negative bacteria, and MRSA bacteria evaluated from 63 studies was 0.90% (95% CI 0.81, 1.21), 0.24% (95% CI 0.18, 0.32), and 0.08% (95% CI 0.05, 0.12), respectively. A meta-regression pinpointed negative association between the frequency of mediastinitis and latitude of study place and positive association between the frequency of mediastinitis and the age of the patient at operation. Multivariate meta-regression showed that prospective cohort design and age of the patients and latitude of study place together or in combination accounted for 17% of heterogeneity for end point frequency of mediastinitis, 16.3% for Gram-positive bacteria, 14.7% for Gram-negative bacteria, and 23.3% for MRSA bacteria.

Conclusion

Evidence from this study suggests the importance of latitude of study place and advanced age as risk factors of mediastinitis. Latitude is a marker of thermally regulated bacterial virulence and other local surgical practice. There is concern of increasing risk of mediastinitis and of MRSA in elderly patients undergoing sternotomy.

Staphylococcus aureus-Associated Skin and Soft Tissue Infections: Anatomical Localization, Epidemiology, Therapy and Potential Prophylaxis

Skin and soft tissue infections (SSTIs) are among the most common infections worldwide. They range in severity from minor, self-limiting, superficial infections to life-threatening diseases requiring all the resources of modern medicine. Community (CA) and healthcare (HA) acquired SSTIs are most commonly caused by Staphylococcus aureus . They have variable presentations ranging from impetigo and folliculitis to surgical site infections (SSIs). Superficial SSTIs may lead to even more invasive infections such as bacteraemia and osteomyelitis. Here we describe the anatomical localization of the different SSTI associated with S. aureus, the virulence factors known to play a role in these infections, and their current epidemiology. Current prevention and treatment strategies are also discussed. Global epidemiological data show increasing incidence and severity of SSTIs in association with methicillin-resistant S. aureus strains (MRSA). CA-SSTIs are usually less morbid compared to other invasive infections caused by S. aureus, but they have become the most prevalent, requiring a great number of medical interventions, extensive antibiotic use, and therefore a high cost burden. Recurrence of SSTIs is common after initial successful treatment, and decolonization strategies have not been effective in reducing recurrence. Furthermore, decolonization approaches may be contributing to the selection and maintenance of multi-drug resistant strains. Clinical studies from the early 1900s and novel autovaccination approaches suggest an alternative strategy with potential effectiveness: using vaccines to control S. aureus cutaneous infections.

Seasonal Variation of Common Surgical Site Infections: Does Season Matter?

OBJECTIVE

To evaluate seasonal variation in the rate of surgical site infections (SSI) following commonly performed surgical procedures.

DESIGN

Retrospective cohort study.

METHODS

We analyzed 6 years (January 1, 2007, through December 31, 2012) of data from the 15 most commonly performed procedures in 20 hospitals in the Duke Infection Control Outreach Network. We defined summer as July through September. First, we performed 3 separate Poisson regression analyses (unadjusted, multivariable, and polynomial) to estimate prevalence rates and prevalence rate ratios of SSI following procedures performed in summer versus nonsummer months. Then, we stratified our results to obtain estimates based on procedure type and organism type. Finally, we performed a sensitivity analysis to test the robustness of our findings.

RESULTS

We identified 4,543 SSI following 441,428 surgical procedures (overall prevalence rate, 1.03/100 procedures). The rate of SSI was significantly higher during the summer compared with the remainder of the year (1.11/100 procedures vs 1.00/100 procedures; prevalence rate ratio, 1.11 [95% CI, 1.04-1.19]; P=.002). Stratum-specific SSI calculations revealed higher SSI rates during the summer for both spinal (P=.03) and nonspinal (P=.004) procedures and revealed higher rates during the summer for SSI due to either gram-positive cocci (P=.006) or gram-negative bacilli (P=.004). Multivariable regression analysis and sensitivity analyses confirmed our findings.

CONCLUSIONS

The rate of SSI following commonly performed surgical procedures was higher during the summer compared with the remainder of the year. Summer SSI rates remained elevated after stratification by organism and spinal versus nonspinal surgery, and rates did not change after controlling for other known SSI risk factors.

Is there a significant seasonality in the occurrence of osteoarticular infections?

Clinical experience suggests fluctuation in the occurrence of osteoarticular infections. We performed a single-centre study during 2004-2012, dividing each year into the four seasons according to the Gregorian calendar. A total of 455 episodes of osteoarticular infections were retrieved. There were 91 prosthetic joint infections (45 of haematogenous origin) and 159 cases of septic arthritis. The median period between early symptoms and diagnosis of infection was 27 days. The overall number of infections per season, cumulated over the 8-year study period, was 119 in spring, 129 in summer, 95 in fall, and 112 in winter, which did not reflect any significant seasonal fluctuation. None of the different subgroups of infections, namely arthroplasties (p for trend = 0.755), haematogenous arthroplasty infections (p = 0.493), gram-negative episodes or arthritis (p = 0.290), showed any season-related fluctuation. We conclude that osteoarticular infections, including haematogenous prosthetic joint infections, do not show any significant seasonality.

The burden of nosocomial staphylococcus aureus bloodstream infection in South Korea: a prospective hospital-based nationwide study

Background

We estimated the nationwide burden of nosocomial S. aureus bloodstream infection (SA-BSI), a major cause of nosocomial infection, in South Korea.

Methods

To evaluate the nationwide incidence of nosocomial SA-BSI, cases of SA-BSI were prospectively collected from 22 hospitals with over 500 beds over 4?months. Data on patient-days were obtained from a national health insurance database containing the claims data for all healthcare facilities in South Korea. The additional cost of SA-BSI was estimated through a matched case?control study. The economic burden was calculated from the sum of the medical costs, the costs of caregiving and loss of productivity.

Results

Three hundred and thirty nine cases of nosocomial SA-BSI were included in the study: 254 cases of methicillin-resistant SA-BSI (MRSA-BSI) and 85 cases of methicillin-susceptible SA-BSI (MSSA-BSI). Death related to BSI occurred in 81 cases (31.9%) of MRSA-BSI and 12 cases (14.1%) of MSSA-BSI. The estimated incidence of nosocomial MRSA-BSI was 0.12/1,000 patient-days and that of nosocomial MSSA-BSI, 0.04/1,000 patient-days. The estimated annual cases of nosocomial BSI were 2,946 for MRSA and 986 for MSSA in South Korea. The additional economic burden per case of nosocomial SA-BSI was US $20,494 for MRSA-BSI and $6,914 for MSSA-BSI. Total additional annual cost of nosocomial SA-BSI was $67,192,559.

Conclusion

In view of the burden of nosocomial SA-BSI, a national strategy for reducing nosocomial SA-BSI is urgently needed in South Korea.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0590-4) contains supplementary material, which is available to authorized users.

Climatic factors and community - associated methicillin-resistant Staphylococcus aureus skin and soft-tissue infections - a time-series analysis study

Skin and soft tissue infections caused by Staphylococcus aureus (SA-SSTIs) including methicillin-resistant Staphylococcus aureus (MRSA) have experienced a significant surge all over the world. Changing climatic factors are affecting the global burden of dermatological infections and there is a lack of information on the association between climatic factors and MRSA infections. Therefore, association of temperature and relative humidity (RH) with occurrence of SA-SSTIs (n = 387) and also MRSA (n = 251) was monitored for 18 months in the outpatient clinic at a tertiary care hospital located in Bhubaneswar, Odisha, India. The Kirby-Bauer disk diffusion method was used for antibiotic susceptibility testing. Time-series analysis was used to investigate the potential association of climatic factors (weekly averages of maximum temperature, minimum temperature and RH) with weekly incidence of SA-SSTIs and MRSA infections. The analysis showed that a combination of weekly average maximum temperature above 33 °C coinciding with weekly average RH ranging between 55% and 78%, is most favorable for the occurrence of SA-SSTIs and MRSA and within these parameters, each unit increase in occurrence of MRSA was associated with increase in weekly average maximum temperature of 1.7 °C (p = 0.044) and weekly average RH increase of 10% (p = 0.097).

Contamination of public buses with MRSA in Lisbon, Portugal: a possible transmission route of major MRSA clones within the community

In a previous study we have shown that public buses in Oporto, the second largest city in Portugal, were highly contaminated with MRSA. Here we describe the results of a similar study performed in another urban area of Portugal–Lisbon, the capital. Between May 2011 and May 2012, hand touched surfaces of 199 public buses in Lisbon were screened for MRSA contamination. Subsequently, the hands of 575 passengers who frequently use these bus lines were also screened. All hand carriers of MRSA were further screened for nasal carriage. The isolates were characterized by PFGE, staphylococcal cassette chromosome (SCC) mec typing, spa typing, MLST and were tested for the presence of mecA, Panton-Valentine leukocidin and arginine catabolic mobile element genes. MRSA contamination was shown in 72 buses (36.2%). The majority of the isolates belonged to three major clones: Clone A was identified as EMRSA-15 defined by pattern PFGE A, spa types t2357/t747/t025/t379/t910, ST22, and SCCmec IVh (n = 21; 29%). Clone B was the New York/Japan clone characterized by PFGE B-t002/t10682-ST5-II (n = 15; 21%). Clone C included isolates with characteristics of the international community-acquired USA300 or related clones, PFGE C-t008-ST8-IVa/IVc/IVg/IVnt/VI (n = 19; 26%). The first two clones are currently the two major lineages circulating in Portuguese hospitals. The hands of 15 individuals were contaminated with MRSA belonging to the nosocomial clones A or B. Eleven of these individuals were not nasal carriers of MRSA and all but one had travelled by public transportation, namely by bus, prior to sampling. In conclusion, public buses in two major cities in Portugal are often contaminated with MRSA representing clones dominant in hospitals in the particular geographic area. MRSA contamination of public transport and the transfer of the bacteria to the hands of passengers may represent a route through which hospital-acquired MRSA clones may spread to the community.

Human-associated methicillin-resistant Staphylococcus aureus from a subtropical recreational marine beach

Reports of Staphylococcus aureus including methicillin-resistant S. aureus (MRSA) detected in marine environments have occurred since the early 1990 s. This investigation sought to isolate and characterize S. aureus from marine waters and sand at a subtropical recreational beach, with and without bathers present, in order to investigate possible sources and to identify the risks to bathers of exposure to these organisms. During 40 days over 17 months, 1,001 water and 36 intertidal sand samples were collected by either bathers or investigators at a subtropical recreational beach. Methicillin-sensitive S. aureus (MSSA) and MRSA were isolated and identified using selective growth media and an organism-specific molecular marker. Antimicrobial susceptibility, staphylococcal cassette chromosome mec (SCCmec) type, pulsed-field gel electrophoresis (PFGE) pattern, multi-locus sequence type (MLST), and staphylococcal protein A (spa) type were characterized for all MRSA. S. aureus was isolated from 248 (37 %) bather nearby water samples at a concentration range of <2-780 colony forming units per ml, 102 (31 %) ambient water samples at a concentration range of <2-260 colony forming units per ml, and 9 (25 %) sand samples. Within the sand environment, S. aureus was isolated more often from above the intertidal zone than from intermittently wet or inundated sand. A total of 1334 MSSA were isolated from 37 sampling days and 22 MRSA were isolated from ten sampling days. Seventeen of the 22 MRSA were identified by PFGE as the community-associated MRSA USA300. MRSA isolates were all SCCmec type IVa, encompassed five spa types (t008, t064, t622, t688, and t723), two MLST types (ST8 and ST5), and 21 of 22 isolates carried the genes for Panton-Valentine leukocidin. There was a correlation (r = 0.45; p = 0.05) between the daily average number of bathers and S. aureus in the water; however, no association between exposure to S. aureus in these waters and reported illness was found. This report supports the concept that humans are a potential direct source for S. aureus in marine waters.

A population based study of seasonality of skin and soft tissue infections: implications for the spread of CA-MRSA

Methicillin resistant Staphylococcus aureus (MRSA) is currently a major cause of skin and soft tissue infections (SSTI) in the United States. Seasonal variation of MRSA infections in hospital settings has been widely observed. However, systematic time-series analysis of incidence data is desirable to understand the seasonality of community acquired (CA)-MRSA infections at the population level. In this paper, using data on monthly SSTI incidence in children aged 0-19 years and enrolled in Medicaid in Maricopa County, Arizona, from January 2005 to December 2008, we carried out time-series and nonlinear regression analysis to determine the periodicity, trend, and peak timing in SSTI incidence in children at different age: 0-4 years, 5-9 years, 10-14 years, and 15-19 years. We also assessed the temporal correlation between SSTI incidence and meteorological variables including average temperature and humidity. Our analysis revealed a strong annual seasonal pattern of SSTI incidence with peak occurring in early September. This pattern was consistent across age groups. Moreover, SSTIs followed a significantly increasing trend over the 4-year study period with annual incidence increasing from 3.36% to 5.55% in our pediatric population of approximately 290,000. We also found a significant correlation between the temporal variation in SSTI incidence and mean temperature and specific humidity. Our findings could have potential implications on prevention and control efforts against CA-MRSA.

The changing epidemiology of methicillin-resistant Staphylococcus aureus in the United States: a national observational study

Methicillin-resistant Staphylococcus aureus (MRSA) can cause major illness and death and impose serious economic costs on patients and hospitals. Community-associated MRSA (CA-MRSA) is a growing problem in US hospitals, which are already dealing with high levels of hospital-associated MRSA (HA-MRSA), but little is known about how patient age and seasonal differences in the incidence of these 2 forms of MRSA affect the epidemic. By using national data on hospitalizations and antibiotic resistance, we estimated the magnitude and trends in annual S. aureus and MRSA hospitalization rates from 2005-2009 by patient age, infection type, and resistance phenotype (CA-MRSA vs. HA-MRSA). Although no statistically significant increase in the hospitalization rate was seen over the study period, the total number of infections increased. In 2009, there were an estimated 463,017 (95% confidence interval: 441,595, 484,439) MRSA-related hospitalizations at a rate of 11.74 (95% confidence interval: 11.20, 12.28) per 1,000 hospitalizations. We observed significant differences in infection type by age, with HA-MRSA-related hospitalizations being more common in older individuals. We also noted significant seasonality in incidence, particularly in children, with CA-MRSA peaking in the late summer and HA-MRSA peaking in the winter, which may be caused by seasonal shifts in antibiotic prescribing patterns.

Seasonality of staphylococcal infections

Characterization of seasonal variation of Staphylococcus aureus is important in understanding the epidemiology of, and designing preventive strategies against this highly virulent and ever-evolving pathogen. In this review, we summarize the findings of epidemiological studies that have evaluated seasonality in S. aureus colonization and infection. Although most studies published to date are methodologically weak, some seasonal variation in the occurrence of S. aureus infection appears to exist, particularly an association of warm-weather months with S. aureus skin and soft-tissue infections. We highlight the limitations of the published literature, and provide suggestions for future studies on this topic.

Presence, distribution, and molecular epidemiology of methicillin-resistant Staphylococcus aureus in a small animal teaching hospital: a year-long active surveillance targeting dogs and their environment

Methicillin-resistant Staphylococcus aureus (MRSA) is known to be present in small animal veterinary clinical environments. However, a better understanding of the ecology and dynamics of MRSA in these environments is necessary for the development of effective infectious disease prevention and control programs. To achieve this goal, a yearlong active MRSA surveillance program was established at The Ohio State University (OSU) Veterinary Medical Center to describe the spatial and molecular epidemiology of this bacterium in the small animal hospital. Antimicrobial susceptibility testing, staphylococcal chromosomal cassette mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE) typing, and dendrogram analysis were used to characterize and analyze the 81 environmental and 37 canine-origin MRSA isolates obtained during monthly sampling events. Overall, 13.5% of surfaces were contaminated with MRSA at 1 or more sampling times throughout the year. The majority of the environmental and canine isolates were SCCmec type II (93.8% and 86.5%, respectively) and USA100 (90.1% and 86.5%, respectively). By PFGE analysis, these isolates were found to be closely related, which reflects a low diversity of MRSA strains circulating in the hospital. For 5 consecutive months, 1 unique pulsotype was the most prevalent across the medical services and was recovered from a variety of surfaces and hospital locations. Carts/gurneys, doors, and examination tables/floors were the most frequently contaminated surfaces. Some surfaces maintained the same pulsotypes for 3 consecutive months. Molecular analysis found that incoming MRSA-positive dogs were capable of introducing a new pulsotype into the hospital environment during the surveillance period. Our results suggest that once a MRSA strain is introduced into the hospital environment, it can be maintained and spread for extended periods of time. These findings can aid in the development of biosecurity and biocontainment protocols aimed at reducing environmental contamination and potential exposures to MRSA in veterinary hospital staff, clients, and patients.