Staphylococcus aureus colonization and infection among drug users: identification of hidden networks

Clonal expansion of community-associated meticillin-resistant Staphylococcus aureus (MRSA) in people who inject drugs (PWID): prevalence, risk factors and molecular epidemiology, Bristol, United Kingdom, 2012 to 2017

Background: In 2015, Bristol (South West England) experienced a large increase in cases of meticillin-resistant Staphylococcus aureus (MRSA) infection in people who inject drugs (PWID).

Aim: We aimed to characterise and estimate the prevalence of MRSA colonisation among PWID in Bristol and test evidence of a clonal outbreak.

Methods: PWID recruited through an unlinked-anonymous community survey during 2016 completed behavioural questionnaires and were screened for MRSA. Univariable logistic regression examined associations with MRSA colonisation. Whole-genome sequencing used lineage-matched MRSA isolates, comparing PWID (screening and retrospective bacteraemia samples from 2012-2017) with non-PWID (Bristol screening) in Bristol and national reference laboratory database samples.

Results: The MRSA colonisation prevalence was 8.7% (13/149) and was associated with frequently injecting in public places (odds ratio (OR): 5.5; 95% confidence interval (CI):1.34–22.70), recent healthcare contact (OR: 4.3; 95% CI: 1.34–13.80) and injecting in groups of three or more (OR: 15.8; 95% CI: 2.51–99.28). People reporting any one of: injecting in public places, injection site skin and soft tissue infection or hospital contact accounted for 12/13 MRSA positive cases (sensitivity 92.3%; specificity 51.5%). Phylogenetic analysis identified a dominant clade associated with infection and colonisation among PWID in Bristol belonging to ST5-SCCmecIVg.

Conclusions: MRSA colonisation in Bristol PWID is substantially elevated compared with general population estimates and there is evidence of clonal expansion, community-based transmission and increased infection risk related to the colonising strain. Targeted interventions, including community screening and suppression therapy, education and basic infection control are needed to reduce MRSA infections in PWID.

The increasing frequency of intravenous drug abuse-associated spinal epidural abscesses: a case series

OBJECTIVEFew studies have been published specifically examining intravenous drug abuse (IVDA)-associated spinal epidural abscesses (SEAs), an unfortunate sequela of the opioid crisis in the United States. Here, the authors examined a series of patients with IVDA-associated SEAs in order to shed light on this challenging disease entity.METHODSThis study is a retrospective chart review of patients presenting with IVDA-associated SEAs at the authors' institution from 2013 to 2018, spanning the statewide implementation of opioid-prescribing restrictions.RESULTSA total of 45 patients presented with IVDA-associated SEAs; 46.5% presented with a neurological deficit. Thirty-one patients underwent surgery for neurological deficit, failure of medical therapy, or both. Nineteen surgical patients underwent a fusion procedure along with decompression. The complication rate was 41.9%, and the mortality rate was 6.7%. The average length of stay was 27.6 days. Patients who underwent surgery within 24 hours of onset of neurological symptoms trended toward more improvement in their American Spinal Cord Association Impairment Scale grade than those who did not (0.5 vs -0.2, p = 0.068). Methicillin-resistant Staphylococcus aureus was isolated as the causative pathogen in 57.8% of patients. Twenty-three patients (51.5%) kept their scheduled clinic follow-up appointments. Of the fusion patients with adequate follow-up, 5 showed bony arthrodesis and 3 had pseudarthrosis. The rate of IVDA-associated SEAs increased after opioid-prescribing restrictions were put in place, from 0.54 cases per month to 1.15 cases per month (p = 0.017).CONCLUSIONSPatients with IVDA-associated SEAs are challenging to treat, with high complication rates and poor follow-up. This disease is increasing in frequency, and opioid-prescribing restrictions did not slow that rise. Community outreach to promote prevention, early medical attention, and medication compliance would benefit this largely publicly funded patient population.

Prevalence, risk factors, phenotypic and molecular characteristics for Staphylococcus aureus carriage in community-based drug users in Guangzhou, China

Background

Staphylococcus aureus (S. aureus), particularly methicillin-resistant Staphylococcus aureus (MRSA), remains the predominant cause of infections in drug users. This cross-sectional study aims to elucidate the prevalence, risk factors, phenotypic and molecular characteristics of S. aureus carriage among community-based drug users.

Methods

All eligible drug users, with both injection and non-injection route of drug administration, were asked to complete questionnaires and collect nasal swabs by trained personal during the period between May and December 2017 in Guangzhou, China. Swabs were processed for identification of S. aureus. Antimicrobial susceptibility test and polymerase chain reaction assays were used to detect phenotypic and molecular characteristics for identified isolates. Univariate and multivariate logistic regression analyses were used to assess risk factors for S. aureus carriage.

Results

Overall, 353 drug users were included in the study and the prevalence of S. aureus carriage was 15.01% (53/353). The prevalence of MRSA carriage was 6.80% (24/353). Cohabitation was a risk factor for S. aureus (adjusted OR = 8.80, 95% CI: 1.89–40.99). The proportion of multidrug resistance was 54.72% for S. aureus isolates and most of these isolates were resistant to penicillin, erythromycin and clindamycin. Seventeen MRSA isolates were multidrug resistant. The results of clonal complexes (CCs) and sequence types (STs) for S. aureus were diverse. The three predominant types for CCs were CC5 (64.15%, 34/53), CC59 (11.32%, 6/53), and CC7 (7.55%, 4/53); and for STs were ST188 (20.75%, 11/53), ST5 (11.32%, 6/53), and ST59 (11.32%, 6/53).

Conclusion

The prevalence of S. aureus nasal carriage was lower while the prevalence of MRSA carriage was moderate compared to previous studies. Phenotypic and molecular characteristics of S. aureus isolates, particularly MRSA isolates, revealed high proportions of antibiotic resistance, indicating the existence of cross-circulation, and implying high opportunity of virulence-related diseases. Decolonization and antibiotic stewardship might be implemented for drug users with MRSA carriage.

A controlled-release oral opioid supports S. aureus survival in injection drug preparation equipment and may increase bacteremia and endocarditis risk

Background

Injection drug use-associated endocarditis (IDUaIE) incidence in Ontario has recently been associated with hydromorphone prescribing rates. Staphylococcus aureus causes the majority of cases of IDUaIE in Ontario and across North America. Hydromorphone controlled-release (Hydromorphone-CR) requires a complex technique for injection and therefore provides multiple opportunities for contamination. Hydromorphone-CR contains several excipients, which could enhance staphylococcal survival and increase risk of contaminating the injectate.

Methods

Used injection drug preparation equipment (cookers/filters) was collected from persons who inject drugs (PWID), rinsed with water, and plated on Mannitol salt agar. Bacterial isolates from bacteremic PWID were used to assess the survival of S. aureus and Streptococcus pyogenes on cookers/filters with Hydromorphone-CR, hydromorphone immediate-release (Hydromorphone-IR) or oxycodone controlled-release (Oxycodone-CR). The solutions spiked with S. aureus were heated and the remaining viable bacteria enumerated.

Results

S. aureus was detected in 12/87 (14%, 95%CI 8–23%) cookers/filters samples used for injection of Hydromorphone-CR. Hydromorphone-CR was the only opioid associated with greater survival of methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) on cookers/filters when compared to sterile water vehicle control. There was a ~2 log reduction in the number of S. aureus that survived when cookers/filters were heated.

Conclusion

14% of all cookers/filters used in the preparation of Hydromorphone-CR were contaminated with S. aureus. Hydromorphone-CR prolongs the survival of MRSA and MSSA in cookers/filters. Heating cookers/filters may be a harm-reduction strategy.

The Heroin Epidemic in America: A Surgeon's Perspective

Background: The United States is currently experiencing a heroin epidemic. Recent reports have demonstrated a three-fold increase in heroin use among Americans since 2007 with a shift in demographics to more women and white Americans. Furthermore, there has been a correlation between the recent opioid epidemic and an increase in heroin abuse. Much has been written about epidemiology and prevention of heroin abuse, but little has been dedicated to the surgical implications, complications, and resource utilization. Discussion: This article focuses on the surgical problems encountered from heroin abuse and how to manage them in a constant effort to improve morbidity and mortality for these heroin abusers.

High Perineal and Overall Frequency of Staphylococcus aureus in People Who Inject Drugs, Compared to Non-Injectors

To investigate the prevalence, distribution, and colonization burden of Staphylococcus aureus (S. aureus) and MRSA in different body sites among people who inject drugs (PWID) and compare it to a control group consisting of non-injectors. In this cross-sectional survey, 49 active PWID from the needle exchange program (NEP) in Malmö, Sweden, and 60 non-injecting controls from an emergency psychiatric inpatient ward at Malmö Addiction Centre were tested for S. aureus (including MRSA) by culture, PCR, and MALDI-TOF. Samples were taken from anterior nares, throat, perineum, and skin lesions if present. Sixty-seven percent of the PWID were colonized with S. aureus, compared to 50% of the controls (P = 0.08). Perineal carriage was significantly more frequent among PWID than in the control group [37 vs 17%, OR 2.96 (95% CI 1.13-7.75), P = 0.03], also after adjusting for sex and age in multivariate analysis [OR 4.01 (95% CI 1.34-12.03)]. Only one individual in the whole cohort (NEP participant) tested positive for MRSA. PWID may be more frequently colonized with S. aureus in the perineum than non-injection drug users, and there was a trend indicating more frequent overall S. aureus colonization in PWID, as well as higher perineal colonization burden. No indication of a high MRSA prevalence among PWID in Sweden was noted. However, further MRSA prevalence studies among PWID are needed. Knowledge about S. aureus colonization is important for the prevention of S. aureus infections with high morbidity in PWID.

Community- and Healthcare-Associated Methicillin-Resistant Staphylococcus aureus Strains: An Investigation Into Household Transmission, Risk Factors, and Environmental Contamination

OBJECTIVE To measure transmission frequencies and risk factors for household acquisition of community-associated and healthcare-associated (HA-) methicillin-resistant Staphylococcus aureus (MRSA). DESIGN Prospective cohort study from October 4, 2008, through December 3, 2012. SETTING Seven acute care hospitals in or near Toronto, Canada. PARTICIPANTS Total of 99 MRSA-colonized or MRSA-infected case patients and 183 household contacts. METHODS Baseline interviews were conducted, and surveillance cultures were collected monthly for 3 months from household members, pets, and 8 prespecified high-use environmental locations. Isolates underwent pulsed-field gel electrophoresis and staphylococcal cassette chromosome mec typing. RESULTS Overall, of 183 household contacts 89 (49%) were MRSA colonized, with 56 (31%) detected at baseline. MRSA transmission from index case to contacts negative at baseline occurred in 27 (40%) of 68 followed-up households. Strains were identical within households. The transmission risk for HA-MRSA was 39% compared with 40% (P=.95) for community-associated MRSA. HA-MRSA index cases were more likely to be older and not practice infection control measures (P=.002-.03). Household acquisition risk factors included requiring assistance and sharing bath towels (P=.001-.03). Environmental contamination was identified in 78 (79%) of 99 households and was more common in HA-MRSA households. CONCLUSION Household transmission of community-associated and HA-MRSA strains was common and the difference in transmission risk was not statistically significant. Infect Control Hosp Epidemiol 2016;1-7.

Association of Environmental Contamination in the Home With the Risk for Recurrent Community-Associated, Methicillin-Resistant Staphylococcus aureus Infection

IMPORTANCE

The role of environmental contamination in recurrent Staphylococcus aureus infections within households and its potential effect on intervention strategies has been debated recently.

OBJECTIVE

To assess whether household environmental contamination increases the risk for recurrent infection among individuals with a community-associated methicillin-resistant S aureus (MRSA) infection.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted from November 1, 2011, to June 30, 2014, in the Columbia University Medical Center catchment area. All patients within 72 hours of presentation with skin or soft-tissue infections and blood, urine, or sputum cultures positive for MRSA were identified. Two hundred sixty-two patients met study inclusion criteria; 83 of these (31.7%) agreed to participate (index patients) with 214 household members. Participants were followed up for 6 months, and 62 of the 83 households (74.7%) completed follow-up. Participants and researchers were blinded to exposure status throughout the study. Follow-up was completed on June 30, 2014, and data were assessed from July 1, 2014, to February 19, 2016.

EXPOSURE

Concordant environmental contamination, defined as having an isolate with the identical staphylococcal protein A and staphylococcal chromosomal cassette mec type or antibiogram type as the index patient's clinical isolate, present on 1 or more environmental surfaces at the time of a home visit to the index patient after infection.

MAIN OUTCOMES AND MEASURES

Index recurrent infection, defined as any self-reported infection among the index patients during follow-up.

RESULTS

One patient did not complete any follow-up. Of the remaining 82 index patients, 53 (64.6%) were female and 59 (72.0%) were Hispanic. The mean age was 30 (SD, 20; range, 1-79) years. Forty-nine of 61 MRSA infections where the clinical isolate could be obtained (80.3%) were due to the epidemic strain USA300. Among the 82 households in which a patient had an index MRSA infection, the clinical isolate was present in the environment in 20 (24.4%) and not found in 62 (75.6%). Thirty-five patients (42.7%) reported a recurrent infection during follow-up, of whom 15 (42.9%) required hospitalization. Thirteen recurrent infections were from the 20 households (65.0%) with and 22 were from the 62 households (35.5%) without environmental contamination (P = .04). Environmental contamination increased the rate of index recurrent infection (incident rate ratio, 2.05; 95% CI, 1.03-4.10; P = .04).

CONCLUSIONS AND RELEVANCE

Household environmental contamination was associated with an increased rate of recurrent infection. Environmental decontamination should be considered as a strategy to prevent future MRSA infections, particularly among households where an infection has occurred.

Staphylococcus aureus infections: transmission within households and the community

Staphylococcus aureus, both methicillin susceptible and resistant, are now major community-based pathogens worldwide. The basis for this is multifactorial and includes the emergence of epidemic clones with enhanced virulence, antibiotic resistance, colonization potential, or transmissibility. Household reservoirs of these unique strains are crucial to their success as community-based pathogens. Staphylococci become resident in households, either as colonizers or environmental contaminants, increasing the risk for recurrent infections. Interactions of household members with others in different households or at community sites, including schools and daycare facilities, have a critical role in the ability of these strains to become endemic. Colonization density at these sites appears to have an important role in facilitating transmission. The integration of research tools, including whole-genome sequencing (WGS), mathematical modeling, and social network analysis, has provided additional insight into the transmission dynamics of these strains. Thus far, interventions designed to reduce recurrent infections among household members have had limited success, likely due to the multiplicity of potential sources for recolonization. The development of better strategies to reduce the number of household-based infections will depend on greater insight into the different factors that contribute to the success of these uniquely successful epidemic clones of S. aureus.

Applications of systems science in biomedical research regarding obesity and noncommunicable chronic diseases: opportunities, promise, and challenges

Interest in the application of systems science (SS) in biomedical research, particularly regarding obesity and noncommunicable chronic disease (NCD) research, has been growing rapidly over the past decade. SS is a broad term referring to a family of research approaches that include modeling. As an emerging approach being adopted in public health, SS focuses on the complex dynamic interaction between agents (e.g., people) and subsystems defined at different levels. SS provides a conceptual framework for interdisciplinary and transdisciplinary approaches that address complex problems. SS has unique advantages for studying obesity and NCD problems in comparison to the traditional analytic approaches. The application of SS in biomedical research dates back to the 1960s with the development of computing capacity and simulation software. In recent decades, SS has been applied to addressing the growing global obesity epidemic. There is growing appreciation and support for using SS in the public health field, with many promising opportunities. There are also many challenges and uncertainties, including methodologic, funding, and institutional barriers. Integrated efforts by stakeholders that address these challenges are critical for the successful application of SS in the future.

Prevalence and behavioural risk factors of Staphylococcus aureus nasal colonization in community-based injection drug users

The aims of this study were to identify Staphylococcus aureus nasal colonization prevalence, behavioural risk factors, and to determine staphylococcal protein A (spa) types in community-based injection drug users (IDUs). Nasal swabs were collected and methicillin susceptibility testing and spa/SCCmec typing were performed on S. aureus isolates. Generalized estimating equations were used to report adjusted odds ratios and 95% confidence intervals. Of the 440 participants, 24·1% were colonized and 5·7% had methicillin-resistant S. aureus (MRSA). Colonization was associated with age, employment/marital status, and the presence of scabs but not with sexually transmitted disease co-infection, HIV status, antibiotic use, hospitalization, or drug treatment programme participation. The USA300 MRSA clone spa types were most common, but 15/49 spa types were new to one of the international databases. Community-based IDUs appear to have different risk factors compared to IDUs from clinical studies. In addition, the number of newly identified spa types indicates a diverse, understudied population.

Molecular characterization of methicillin-resistant Staphylococcus aureus clinical isolates obtained from the Rikers Island Jail System from 2009 to 2013

Inmates of Rikers Island jail potentially introduce Staphylococcus aureus into New York State prisons upon transfer. In this study, methicillin-resistant Staphylococcus aureus isolates (n = 452), collected from infected inmates (2009 to 2013), were characterized. spa type t008 was the predominant clone identified, accounting for 82.3% of the isolates, with no evidence of mupirocin or chlorhexidine resistance.

Environmental contamination as a risk factor for intra-household Staphylococcus aureus transmission

BACKGROUND

The household is a recognized community reservoir for Staphylococcus aureus. This study investigated potential risk factors for intra-household S. aureus transmission, including the contribution of environmental contamination.

METHODS

We investigated intra-household S. aureus transmission using a sample of multiple member households from a community-based case-control study examining risk factors for CA-MRSA infection conducted in Northern Manhattan. During a home visit, index subjects completed a questionnaire. All consenting household members were swabbed, as were standardized environmental household items. Swabs were cultured for S. aureus. Positive isolates underwent further molecular characterization. Intra-household transmission was defined as having identical strains among two or more household members. Multiple logistic regression was used to identify independent risk factors for transmission.

RESULTS

We enrolled 291 households: 146 index cases, 145 index controls and 687 of their household contacts. The majority of indexes were Hispanic (85%), low income (74%), and female (67%), with a mean age of 31 (range 1-79). The average size of case and control households was 4 people. S. aureus colonized individuals in 62% of households and contaminated the environment in 54% of households. USA300 was the predominant clinical infection, colonizing and environmental strain. Eighty-one households had evidence of intra-household transmission: 55 (38%) case and 26 (18%) control households (P<.01). Environmental contamination with a colonizing or clinical infection strain (aOR: 5.4 [2.9-10.3] P<.01) and the presence of a child under 5 (aOR: 2.3 [1.2-4.5] P = .02) were independently associated with transmission. In separate multivariable models, environmental contamination was associated with transmission among case (aOR 3.3, p<.01) and control households (aOR 27.2, p<.01).

CONCLUSIONS

Environmental contamination with a colonizing or clinical infection strain was significantly and independently associated with transmission in a large community-based sample. Environmental contamination should be considered when treating S. aureus infections, particularly among households with multiple infected members.

Trends in Staphylococcus aureus bacteraemia and impacts of infection control practices including universal MRSA admission screening in a hospital in Scotland, 2006-2010: retrospective cohort study and time-series intervention analysis

OBJECTIVES

To describe secular trends in Staphylococcus aureus bacteraemia (SAB) and to assess the impacts of infection control practices, including universal methicillin-resistant Staphylococcus aureus (MRSA) admission screening on associated clinical burdens.

DESIGN

Retrospective cohort study and multivariate time-series analysis linking microbiology, patient management and health intelligence databases.

SETTING

Teaching hospital in North East Scotland.

PARTICIPANTS

All patients admitted to Aberdeen Royal Infirmary between 1 January 2006 and 31 December 2010: n=420 452 admissions and 1 430 052 acute occupied bed days (AOBDs).

INTERVENTION

Universal admission screening programme for MRSA (August 2008) incorporating isolation and decolonisation. PRIMARY AND SECONDARY MEASURES: Hospital-wide prevalence density, hospital-associated incidence density and death within 30 days of MRSA or methicillin-sensitive Staphylococcus aureus (MSSA) bacteraemia.

RESULTS

Between 2006 and 2010, prevalence density of all SAB declined by 41%, from 0.73 to 0.50 cases/1000 AOBDs (p=0.002 for trend), and 30-day mortality from 26% to 14% (p=0.013). Significant reductions were observed in MRSA bacteraemia only. Overnight admissions screened for MRSA rose from 43% during selective screening to >90% within 4 months of universal screening. In multivariate time-series analysis (R(2) 0.45 to 0.68), universal screening was associated with a 19% reduction in prevalence density of MRSA bacteraemia (-0.035, 95% CI -0.049 to -0.021/1000 AOBDs; p<0.001), a 29% fall in hospital-associated incidence density (-0.029, 95% CI -0.035 to -0.023/1000 AOBDs; p<0.001) and a 46% reduction in 30-day mortality (-15.6, 95% CI -24.1% to -7.1%; p<0.001). Positive associations with fluoroquinolone and cephalosporin use suggested that antibiotic stewardship reduced prevalence density of MRSA bacteraemia by 0.027 (95% CI 0.015 to 0.039)/1000 AOBDs. Rates of MSSA bacteraemia were not significantly affected by screening or antibiotic use.

CONCLUSIONS

Declining clinical burdens from SAB were attributable to reductions in MRSA infections. Universal admission screening and antibiotic stewardship were associated with decreases in MRSA bacteraemia and associated early mortality. Control of MSSA bacteraemia remains a priority.