Injecting drug use and community-associated methicillin-resistant Staphylococcus aureus infection

Impact of donor multidrug-resistant organisms on solid organ transplant recipient outcomes

BACKGROUND

The impact of donor colonization or infection with multidrug-resistant organisms (MDROs) on solid organ transplant (SOT) recipient outcomes remains uncertain. We thus evaluated the association between donor MDROs and risk of posttransplant infection, graft failure, and mortality.

METHODS

A multicenter retrospective cohort study was performed. All SOT recipients with a local deceased donor were included. The cohort was divided into three exposure groups: recipients whose donors had (1) an MDRO, (2) a non-MDRO bacterial or candidal organism, or (3) no growth on cultures. The primary outcomes were (1) bacterial or invasive candidal infection within 3 months and (2) graft failure or death within 12 months posttransplant. Mixed effect multivariable frailty models were developed to evaluate each association.

RESULTS

Of 658 total SOT recipients, 93 (14%) had a donor with an MDRO, 477 (73%) had a donor with a non-MDRO organism, and 88 (13%) had a donor with no organisms on culture. On multivariable analyses, donor MDROs were associated with a significantly increased hazard of infection compared to those with negative donor cultures (adjust hazard ratio [aHR] 1.63, 95% CI 1.01-2.62, p = .04) but were not associated with graft failure or death (aHR 0.45, 95% CI 0.15-1.36, p = .16).

CONCLUSIONS

MDROs on donor culture increase the risk of early posttransplant infection but do not appear to affect long-term graft or recipient survival, suggesting organ donors with MDROs on culture may be safely utilized. Future studies aimed at reducing early posttransplant infections associated with donor MDROs are needed.

Opioid Use Disorder and Associated Infectious Disease: The Role of the Laboratory in Addressing Health Disparities

BACKGROUND

Opioid use disorder, defined as a pattern of problematic opioid use leading to clinically significant impairment, has resulted in considerable morbidity and mortality throughout the world. This is due, at least in part, to the marginalized status of patients with opioid use disorder, limiting their access to appropriate laboratory testing, diagnosis, and treatment. Infections have long been associated with illicit drug use and contribute considerably to morbidity and mortality. However, barriers to testing and negative stigmas associated with opioid use disorder present unique challenges to infectious disease testing in this patient population.

CONTENT

This review addresses the associations between opioid use disorder and infectious organisms, highlighting the health disparities encountered by patients with opioid use disorder, and the important role of laboratory testing for diagnosing and managing these patients.

SUMMARY

Infections are among the most frequent and adverse complications among patients with opioid use disorder. As a result of health disparities and systemic biases, patients that misuse opioids are less likely to receive laboratory testing and treatment. However, laboratories play a crucial in identifying patients that use drugs illicitly and infections associated with illicit drug use.

Compliance to antibiotic guidelines leads to more appropriate use of antibiotics in skin and soft tissue infections in injecting drug users

Background: Knowledge about the treatment of skin and soft tissue infections in injecting drug users in countries with a low prevalence of antibiotic resistance is limited. We investigated bacterial antibiotic resistance and treatment of skin and soft tissue infections in Norwegian drug users. Methods: We performed a two year clinical cross-sectional observational study in a Norwegian hospital. Data were collected retrospectively from hospital records. We examined bacteriological findings and antibiotic resistance, and evaluated compliance to treatment guidelines and appropriateness of empirical antibiotic therapy relative to results of cultures and susceptibility testing. Descriptive and univariate analyses were performed. Results: Hundred and thirty-five injecting drug users were admitted with skin and soft tissue infection in the study period. Cultures were obtained from 103 (77%) abscesses and eight (24%) erysipelas and cellulitis, with bacterial growth in 80 (78%) and five (63%), respectively. Streptococci and staphylococci were the most prevalent bacteria, but methicillin-resistant Staphylococcus aureus was found in only one patient. Compliance to hospital antibiotic guidelines was 70%. Ninety-one per cent of patients in the compliant and 79% in the non-compliant group were given effective empirical antibiotics (p = .334). In the non-compliant group, significantly more patients received broad-spectrum empirical antibiotics (p < .001). In 30 cases where adjustment of antibiotic therapy was possible according to susceptibility testing, this was performed in only 14 cases. Conclusions: Bacteria and resistance patterns did not differ significantly from the skin and soft tissue infections in the general population in Norway. Compliance to antibiotic guidelines led to significantly less use of broad-spectrum antibiotics and to good bacterial coverage. General guidelines for treatment should be applied to injecting drug users with skin and soft tissue infections.

Efficacy and Safety of Tedizolid and Linezolid for the Treatment of Acute Bacterial Skin and Skin Structure Infections in Injection Drug Users: Analysis of Two Clinical Trials

INTRODUCTION

Injection drug users (IDUs) often develop acute bacterial skin and skin structure infections (ABSSSI) and use emergency departments as their primary source for medical care.

METHODS

A post hoc subgroup analysis of two randomized trials examined the efficacy and safety of tedizolid in the treatment of ABSSSI in IDUs. IDUs (n = 389) were identified from two pooled phase 3 trials (NCT01170221, NCT01421511) in patients with ABSSSI (n = 1333). Patients were randomly assigned to tedizolid phosphate (200 mg once daily, 6 days) or linezolid (600 mg twice daily, 10 days). Primary endpoint was ≥ 20% reduction in lesion area from baseline at 48 -72 h. Secondary endpoints included investigator-assessed clinical and microbiological response at the post-therapy evaluation (PTE).

RESULTS

Wound infection was more common in IDUs (52.2%), while cellulitis/erysipelas was more common in non-IDUs (55.9%). Most infections were due to Staphylococcus aureus (IDUs, 75.2%; non-IDUs, 85.6%), while oral pathogens were more prevalent in IDUs. Early clinical success rates for tedizolid and linezolid were 82.5% and 79.6% in IDUs and 81.3% and 79.3% for non-IDUs, respectively; responses at PTE were similar. Microbiological response per pathogen was similar between treatment groups. Rates of treatment-emergent adverse events (AEs) in IDUs were comparable between tedizolid (46.2%) and linezolid (47.8%) arms, while lower incidence of gastrointestinal AEs was observed with tedizolid (20.3%) than with linezolid (25.1%).

CONCLUSION

Efficacy and safety of tedizolid and linezolid in the treatment of ABSSSI was similar in IDUs and non-IDUs, supporting the use of oxazolidinones in treating ABSSSIs in IDUs.

FUNDING

Merck & Co., Inc., Kenilworth, NJ, USA.

Drug Use Is Associated With Purulent Skin and Soft Tissue Infections in a Large Urban Jail: 2011-2015

Background

Skin and soft tissue infections (SSTIs) are a common problem in jails in the United States. This study aimed to identify factors associated with purulent SSTIs in the New York City jail system.

Methods

We conducted a case-control study of purulent SSTIs at the New York City jail. Cases were matched to controls by visit date to the jail’s urgent care clinic. Bivariate and multivariable analyses were conducted using conditional logistic regression.

Results

From April 2011 to April 2015, 1010 cases of SSTIs were identified and matched to 1010 controls. In multivariable analyses, report upon entry to jail of current injection drug use (odds ratio [OR], 2.76; 95% confidence interval [CI], 1.77–4.31), current snorting of drugs (OR, 1.50; 95% CI, 1.12–2.00), current heroin use (OR, 1.53; 95% CI, 1.08–2.17), current cocaine use (OR, 1.76; 95% CI, 1.18–2.65), and antibiotic use within the previous 6 months (OR, 4.05; 95% CI, 2.98–5.49) were significantly associated with SSTI diagnosis.

Conclusions

Skin and soft tissue infections were strongly associated with a history of drug use at jail entry. Targeting intravenous drug use may be a preventive strategy for SSTIs in this population. Strategies such as harm reduction programs may be investigated.

Prevalence and risk factors for methicillin-resistant Staphylococcus aureus in an HIV-positive cohort

BACKGROUND

Persons living with HIV (PLWH) are disproportionately burdened with methicillin-resistant Staphylococcus aureus (MRSA). Our objective was to evaluate prevalence and risks for MRSA colonization in PLWH.

METHODS

Adults were recruited from Johns Hopkins University AIDS Service in Baltimore, Maryland. A risk questionnaire and specimen collection from anatomic sites with culture susceptibility and genotyping were completed. Generalized estimating equation modeling identified MRSA colonization risk factors.

RESULTS

Of 500 participants, most were black (69%), on antiretroviral therapy (ART) (87%), with undetectable viral loads (73.4%). Median CD4 count was 487 cells/mm(3) (interquartile range, 316-676.5 cells/mm(3)). MRSA prevalence was 15.4%, predominantly from the nares (59.7%). Forty percent were nares negative but were colonized elsewhere. Lower odds for colonization were associated with recent sexual activity (adjusted odds ratio [AOR] = 0.84, P < .001) and ART (AOR = 0.85, P = .011). Increased odds were associated with lower income (<$25,000 vs >$75,000; AOR = 2.68, P < .001), recent hospitalization (AOR = 1.54, P < .001), incarceration (AOR = 1.55, P < .001), use of street drugs (AOR = 1.43, P < .001), and skin abscess (AOR = 1.19, P < .001).

CONCLUSIONS

Even with high MRSA prevalence, the proportion identified through nares surveillance alone was low, indicating the importance of screening multiple anatomic sites. Associations were not found with same-sex coupling or black race. MRSA prevention might be a benefit of ART in PLWH.

Shooting up: the interface of microbial infections and drug abuse

Illicit drug control has been on the global agenda for more than a century. Infections have long been recognized as one of the most serious complications of drug abuse. Drug users are susceptible to pulmonary, endovascular, skin and soft tissue, bone and joint, and sexually transmitted infections caused by a wide range of bacterial, viral, fungal and protozoal pathogens. In addition, injection drug users are at increased risk for parenterally acquired infections such as human immunodeficiency virus, hepatitis B virus, hepatitis C virus, tetanus and malaria. Factors related to drug use, such as unsterile injection practices, contaminated drug paraphernalia and drug adulterants, increase the exposure to microbial pathogens. Illicit drugs also affect several components of the complex immune system and thus modulate host immunity. In addition, lifestyle practices such as multiple sexual partners, overcrowded housing arrangements and malnutrition serve as co-factors in increasing the risk of infection. In this review we present an overview of the unique aspects of microbial pathogenesis, immune modulation and common infections associated with drug use. We have restricted the definition of drug abuse to the use of illegal drugs (such as opiates, marijuana, cocaine, heroin and amphetamines), not including alcohol and nicotine.

Public health surveillance for methicillin-resistant Staphylococcus aureus: comparison of methods for classifying health care- and community-associated infections

OBJECTIVES

We compared 3 methods for classifying methicillin-resistant Staphylococcus aureus (MRSA) infections as health care associated or community associated for use in public health surveillance.

METHODS

We analyzed data on MRSA infections reported to the Michigan Department of Community Health from October 1, 2004, to December 31, 2005. Patient demographics, risk factors, infection information, and susceptibility were collected for 2151 cases. We classified each case by the health care risk factor, infection-type, and susceptibility pattern methods and compared the results of the 3 methods.

RESULTS

Demographic, clinical, and microbiological variables yielded similar health care-associated and community-associated distributions when classified by risk factor and infection type. When 2 methods yielded the same classifications, the overall distribution was similar to classification by 3 methods. No specific combination of 2 methods was superior.

CONCLUSIONS

MRSA categorization by 2 methods is more accurate than it is by a single method. The health care risk factor and infection-type methods yield comparable classification results. Accuracy is increased by using more variables; however, further research is needed to identify the optimal combination.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

Community-associated methicillin-resistant Staphylococcus aureus is prevalent in wounds of community-based injection drug users

Injection drug users (IDUs) have an elevated risk for carriage of Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). Cutaneous injection-related infections are common in IDUs but detailed studies are few. Based on a subsample of 218 individuals from a community-recruited cohort of IDUs at a supervised injection facility, we investigated the microbiology and related antibiotic susceptibility profiles of isolates from 59 wounds. Twenty-seven percent of subjects had at least one wound and 25 (43%) were culture positive for S. aureus alone [14 MRSA and 11 (19%) methicillin-susceptible (MSSA) isolates]. Sixteen of 18 MRSA isolates were classified as community associated (CA) by the presence of genes encoding for PVL. MRSA and MSSA occurred in mixed infection with other organisms on three and six occasions, respectively. All CA-MRSA isolates were susceptible to tetracycline, vancomycin and linezolid but only 13% were susceptible to clindamycin compared to 63% of MSSA isolates. The frequency of CA-MRSA is a cause for concern in wound infection in the IDU setting.

Community-associated methicillin-resistant Staphylococcus aureus infections

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has been recognized for over a decade, and usually refers to MRSA identified in previously healthy individuals with no recognized MRSA risk factors. Infections range from minor skin and soft tissue infections, through to severe pneumonia and necrotizing fasciitis. This review summarizes the current data on the epidemiology and molecular features of CA-MRSA, in addition to diagnosis and therapeutic measures. We also refer to current national guidelines for the management of these infections. Areas of agreement include the important genotypic and phenotypic differences of community MRSA strains compared with hospital strains. Areas of controversy include the precise epidemiological definition of community-acquired/associated MRSA. Fortunately, true CA-MRSA can be differentiated from hospital MRSA by molecular techniques, as discussed herein. Recent interest has focused on the changing epidemiology of CA-MRSA. Worldwide, CA-MRSA is now seen outside of the initial specific population groups, and in the USA, the successful USA300 community strain is beginning to spread back into hospitals. Reasons why USA300 remains relatively uncommon in Europe are unclear. Topics timely for research include the investigation of the epidemiology of infections and evolutionary genomics.

Clinical, molecular and epidemiological description of a cluster of community-associated methicillin-resistant Staphylococcus aureus isolates from injecting drug users with bacteraemia

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an increasing problem, predominantly in previously healthy individuals including notable risk groups such as the homeless, those who play close-contact sports, military personnel, men who have sex with men (MSM) and injecting drug users (IDUs). Over a 5-month period, four IDUs were admitted to Addenbrooke's Hospital, Cambridge, UK, with MRSA bacteraemia. All four patients presented with complex clinical features, with more than one focus of infection, and were linked epidemiologically. The atypical antibiogram of the MRSA isolates (ciprofloxacin-susceptible) prompted further characterization, both phenotypically (antibiotic resistance typing; phage typing) and genotypically (detection of toxin genes by PCR; pulsed-field gel electrophoresis (PFGE); Staphylococcal chromosome cassette (SCC) mec typing; multi-locus sequence typing (MLST)). All four isolates had similar antibiograms, were Panton-Valentine Leucocidin (PVL) toxin gene-negative, harboured SCCmec type IV and were closely related as shown by phage typing and PFGE. These isolates were representatives of a community-associated clone, ST1-MRSA-IV, known to be circulating in IDUs in the UK since 2001. This paper presents a detailed description of the clinical, microbiological and epidemiological features of a series of CA-MRSA bacteraemias in IDUs in the UK.

Patterns and determinants of inappropriate antibiotic use in injection drug users

BACKGROUND

Inappropriate antibiotic use contributes to the emergence and spread of drug resistant infections. Though injection drug users are at increased risk for drug resistant infections, few studies have examined antibiotic use in this population.

OBJECTIVE

To understand patterns and determinants of antibiotic use among injection drug users.

METHODS

Five focus groups were conducted with 28 current injection drug users recruited from a syringe exchange program in Philadelphia and analyzed using the constant comparative method to identify emergent themes. Twenty-six participants also completed a written survey instrument.

RESULTS

Injection drug users reported frequent antibiotic exposure, with 12 of 26 participants reporting use of antibiotic medications at least once in the previous 30 days. Participants reported several patterns of antibiotic use that were potentially harmful, including delays in seeking medical care, failing to fill prescriptions, obtaining antibiotics from non-provider sources, and poor adherence to prescribed regimens. The major determinants of inappropriate antibiotic use were delayed recognition of severity of illness, reluctance to wait to be seen, previous mistreatment by providers, lack of insurance, prioritizing purchasing drugs of abuse over antibiotics, forgetting to take antibiotics because of distractions that accompany drug use, concerns about interactions between antibiotics and other substances, and an irregular diet. Additionally, injection drug users commonly misunderstood the concept of antibiotic resistance and equated it with tolerance.

CONCLUSIONS

Injection drug users reported potentially dangerous antibiotic use behaviors and described determinants of these behaviors. Outreach and educational interventions to improve antibiotic use should target high-risk populations, such as injection drug users, and consider their distinct antibiotic use behaviors and determinants.

Community-Associated Methicillin-Resistant Staphylococcus aureus in the Pediatric Population

PURPOSE

To review the epidemiology and prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), define the differences between community-acquired and hospital-acquired strains, highlight the advantages and disadvantages of antibiotics commonly used to treat infections caused by this pathogen, and identify strategies to limit the spread of this organism and prevent future outbreaks.

DATA

Literature was accessed through MEDLINE using the search terms community-acquired methicillin-resistant Staphylococcus aureus, community-associated methicillin-resistant Staphylococcus aureus, CA-MRSA, pediatrics, and children. Articles evaluated were published in the English language and limited to human studies. References of literature identified by initial search techniques were reviewed for additional relevant articles.

DATA SYNTHESIS

Community-associated methicillin-resistant Staphylococcus aureus has become a prominent pathogen in pediatric patients in the last ten years. Its increasing prevalence has been reported throughout the United States, and it is the cause of over one half of all skin and soft tissue infections seen in many hospitals and emergency departments. The risk factors for infection with this pathogen differ from those associated with hospital-acquired strains. Mild to moderate infections can generally be treated with oral antibiotics, while more serious infections may require parenteral therapy. Sulfamethoxazole/trimethoprim and clindamycin are the preferred oral agents due to their efficacy, tolerability, well established side effect profiles, and cost. Vancomycin is the standard of care for parenteral therapy, although clindamycin is an acceptable parenteral alternative. More costly agents such as linezolid, daptomycin, and quinupristin/dalfopristin should be reserved for patients with severe infections, multiple allergies, or in strains with unusual resistance patterns. The best way to prevent and control outbreaks is to maintain standard infection control procedures including excellent hand hygiene.

CONCLUSIONS

CA-MRSA is a serious and frequently seen pathogen. Proper antibiotic selection that takes into account patient factors, disease severity, ease of administration, and cost is necessary to maximize favorable patient outcomes.