Risk Factors Of Infective Endocarditis In Persons Who Inject Drugs

doi:10.21203/rs.2.22402/v1

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Risk Factors Of Infective Endocarditis In Persons Who Inject Drugs

https://doi.org/10.21203/rs.2.22402/v1

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published 05 Jun, 2020

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Background: The rising incidence of infective endocarditis (IE) among people who inject drugs (PWID) has been a major concern across North America. Details of injection practices leading to IE are not well characterized.

Methods: A case-control study, using one-on-one interviews to understand risk factors and injection practices associated with IE among PWID was conducted. Eligible participants included those who had injected drugs within the last 3 months, were > 18 years old and either never had or were currently admitted for an IE episode. Cases were recruited from the tertiary care centers and controls were recruited from outpatient clinics in patients without IE and addiction clinics in London, Ontario.

Results: 33 cases (PWID IE+) and 102 controls (PWID but IE-) were interviewed. Using clean injection equipment from the provincial distribution network was a protective factor against IE (p<0.001). Furthermore, using lighters during the injection process was also protective for IE (OR 2.5; 95% CI 1.11–5.63). Female sex (OR 3.63; 95% CI 1.58-8.36) and injection into multiple sites (OR 4.31; 95% CI 1.33-13.93) were associated with IE. Injection into the feet (57.6% cases; 36.6% control; p= 0.034) was also associated with IE.

Discussion: Our pilot study highlights the importance of distributing clean injection materials for IE prevention. Injection into multiple areas may indicate a greater difficulty in accessing common and safer injection sites such as the arm, and thus multi-site injections may be a surrogate marker for injection-related venous damage in entrenched drug users. Moreover, the use of lighters may be correlated with the best practice of heating preparations of drugs prior to injection, which is known to reduce bacterial burden. Lastly, gender differences in injection techniques, which may place women at higher risk of IE, requires further study.

Health Economics & Outcomes Research

injection drug use

infective endocarditis

HIV

hepatitis C

opioid precedence

opioid epidemic

hydromorphone

female PWID

There has been a rising incidence of infective endocarditis (IE) among people who inject drugs (PWID), paralleling the opioid epidemic in North America(1–6). This infectious complication of intravenous drug use (IVDU) is associated with significant morbidity and mortality requiring extensive and costly(1,2) multidisciplinary care(7). PWID are at risk of IE due to: comorbidities of HIV, hepatitis C and skin and soft tissue infections; non-sterile injection practices; and the reuse of injection drug preparation equipment (IDPE)(2,4,8–12).

In June of 2016, a public health emergency was declared in London, Ontario, Canada following an increase in IE(13) and injection-related HIV(14). We identified an association between increasing IVDU associated IE hospitalization and increasing prescriptions of hydromorphone across Ontario(4). Prescription rates for hydromorphonecontrolled-release (CR) (Hydromorph Contin ®, Purdue Pharma, Pickering, Ontario) in London are in the top quartile in Ontario (4,13,15). Furthermore, studies have shown that the misuse of prescribed opiates such as hydromorphone-CR amplify risk of infections due to the nature of how these substances are prepared for injection(11,16–18). Hydromorphone-CR is difficult to dissolve in solution, often requiring PWID to use unsterile methods to prepare injectates. Furthermore, the components of hydromorphone-CR capsules that provide the controlled release, increase survival of HIV(19) and Staphylococcus aureus(12), which cause the vast majority of IE cases(7). Moreover, residual drug remains in cookers and filters after an initial injection, allowing PWID to resolubilize the remaining drug and conduct multiple injections(11,14,16,19,20) (Fig. 1). This high-risk practice of multiple injections, involves keeping, sharing and reusing injection drug preparation equipment (IDPE), which increases infections among PWID(14,16,20). However, studies have also found that heating the injectate before injection of hydromorphone-CR can significantly reduce the inoculum of bacteria causing IE(12).

Based on the timing of increased IE incidence in London and the shift of drug preference to hydromorphone(4), the objective of our study was to identify which demographic variables injection practices would pose a risk for IE. We hypothesized that factors associated with hydromorphone-CR use, such as reuse of equipment or failure to heat the injectate were related to the outbreak. We also sought to clarify the demographics and injection practices of PWID in London.

Design/Setting/Participants

We conducted a case-control study where persons who inject drugs (PWID) ≥ 18 years were eligible for participation. Injection drug use status was identified through self-reported intravenous drug use within the last 3 months. Our cases were PWID with “Definite IE”, on the basis of Modified Duke Criteria(21). Cases were recruited from the three tertiary care centers in London that provide inpatient care for all patients with endocarditis. Outpatients being followed up for recent IE (within 6 weeks) were also recruited as cases through the outpatient Infectious Disease clinics covering London. Our controls were PWID with no history of IE episodes; these participants were recruited from addiction clinics and outpatient clinics seeing patients with cellulitis and other infectious complications of injection drug use in London, Ontario. Recruitment for controls were conducted at Addiction Services of Thames Valley, Regional HIV/AIDS Connection, St Joseph’s Health Care Infectious Disease clinics and the London Intercommunity Health Center. This choice of sites allowed us to observe a diverse subset of participants along the spectrum of injection practices. We recruited participants from August 11, 2016 to July 27, 2018.

Anonymous interviews were conducted with a questionnaire querying: demographic data; medical history pertaining to current and previous IE episodes (if any) and other infectious complications, and; history of intravenous drug use in the past 3 months and over one’s lifetime. Each participant was then assigned an identification number. Patient medical records were consulted by Infectious Disease physicians to verify definite cases of IE. Study data were digitized and managed using REDCap electronic data capture tools hosted at Lawson Health Research Institute(22). The study protocol was approved by an institutional board review (Health Sciences Research Ethics Board, Western University). Written informed consent was obtained from all participants. Participants were compensated for their time with a CAD$10 Tim Horton’s coffee shop gift card. ໿Reporting of all aspects of this study adhered to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cohort studies(23). Final recruitment was 102 controls and 33 cases.

Power Analysis

The exposure of interest was the use of hydromorphone-CR and its association with IE, particularly the practice of heating and reusing IDPE (cookers and filters) for injection. We estimated a prevalence of 20% in controls and 50% in cases with a corresponding odds ratio of 4.0. As such, a minimum of 30 cases and 60 controls were needed to detect these associations, with a power of 80%, 2-tailed alpha of 0.05, and continuity correction.

Statistical analysis

Univariate analysis was performed in RStudio 1.1.453 IDE (RStudio, Inc., Boston, MA) and SPSS 25 (IBM Corp., Armonk, NY). Various sociodemographic factors, and drug use patterns were compared between cases and controls to determine their association with IE.

One hundred and forty-one interviews were conducted, with 135 individuals being included into the final study. Of the 34 case interviews conducted, 1/34 (3%) was excluded from the final study as this individual did not have a definite episode of IE; thus, 33/34 (97%) were included in the final study. Of the 107 control interviews conducted, 4/107 (4%) were excluded as they had stopped injecting drugs for more than 3 months prior to interview. Moreover, 1/107 (1%) was excluded due to inconsistent answers being provided between the different sections of the interview. In finality, 102/107 (95%) controls were included in the final study. The demographic characteristics of the two cohorts are shown in Table 1. There was a significantly greater proportion of female PWID with infective endocarditis (48.5% cases; 20.6% controls; OR 3.63; 95% CI 1.58–8.36; p = 0.002). Cases also more commonly had completed secondary or post-secondary education (did not have incomplete degrees) compared to controls (61.3% cases; 33.7% controls; p = 0.01). Controls and cases were similar in regard to age, race, housing status, concurrent HIV and hepatitis C infections and past complications.

Cases and controls injected a wide range of drugs (Table 2). The most commonly injected drug in both groups was hydromorphone-CR; however, hydromorphone-CR use was not significantly different between the two cohorts (90.9% cases; 81.4% controls, p = 0.197). Hydromorphone-immediate release tablets was the second most commonly injected drug. Furthermore, there was a trend towards crystal methamphetamine being injected by control participants more than case participants (54.4% cases; 78.4% controls; p = 0.07). Injection of fentanyl tablets or patches was sparse among PWID in London at this time.

Injection location data (Table 2) showed that the arm was the most commonly used primary location for injection with controls tending to inject more frequently into the arm than cases (51.5% cases; 69.6% controls; p = 0.058). PWID with IE were more likely to have more than one anatomical site for frequent injection (21.2% cases; 5.9% controls; OR 4.31; 95% CI 1.33–13.93; p = 0.0009). Additionally, in the last three months, cases were significantly more likely to inject in the feet (57.6% cases; 36.6% controls; p = 0.034), and trended to inject more often in the neck (63.6% cases; 46% controls; p = 0.079) and breast tissue (6.7% cases; 0% controls; p = 0.077) (Table 2).

The injection preparation techniques and behaviours of cases and controls are highlighted in Table 3. Both cases and controls used cookers to prepare drugs for injection at a rate of 50–60%. Controls were significantly more likely to use a Stericup, which is distributed in the IDPE kits by the provincial government (42.4% cases; 84.2% controls; p < 0.001) to prepare drugs. Furthermore, PWID with IE were more likely to use cooker types that were not listed in our surveys (Stericup, spoon, glass bottle or shot glass) than controls (48.5% cases; 11.8% controls; OR: 7.059; 95% CI 2.84–17.544; p < 0.001).

A cellulose filter was commonly used by both groups (96%). Both groups indicated reusing their filters at 63.7% controls and 60.6% cases for multiple injections. Additionally, both groups stored their filters in cookers or in pockets and/or at body temperature in similar proportions. Many participants (18% controls and 15.6% cases) shared their filters.

In terms of reusing the hydromorphone-CR capsule for multiple injections (‘washes’), both cases and controls conducted second washes frequently (87.9% cases; 74.5% controls; OR: 2.48; 95% CI 0.8–7.73).

We did not find that heating drugs was protective; however, we did find that controls used lighters as crushers for drug preparation significantly more than cases (58.8% vs 36.4%; p = 0.025), suggesting that controls may have greater accessibility to a heating source.

While there were no significant differences between cohorts in the frequencies of needle and syringe sharing or reuse, the rates of reuse are high with 74.5% of controls and 69.7% of cases reporting reuse of needles. Furthermore, the rate of reuse for syringe barrels also remains high with 66.7% of controls and 60.6% of cases reporting reuse.

Our cases primarily had tricuspid-valve endocarditis and the most common organism causing IE was methicillin-sensitive Staphylococcus aureus (Table 4).

Understanding the risk factors associated with IE in PWID is important in developing harm reduction strategies. We hypothesized that the use of hydromorphone-CR and multiple washes of equipment would be risk factors for IE and that heating of drug preparations would be protective against the disease. We did not find a significant increase in hydromorphone-CR use in IE patients vs controls (91% vs 84%; OR 2.29; 95% CI 0.63-8.29) or an increased likelihood of performing multiple washes with hydromorphone-CR (88% vs 74%; OR: 2.48; 95% CI 0.8-7.73). Our sample size was likely inadequate to identify these differences because the frequencies of both of these behaviours were much greater in both groups than expected. However, a companion study surveying PWID in London found that PWID with HIV were 22.12 (4.51 to 108.59) times more likely to share cookers, filters or washes in their three-month recall period(14). The high-risk practice of injecting prescription opioids from equipment that is reused multiple times is prevalent in our region and appears to be related to a high incidence of infectious complications, including a very high incidence of IE(4). The trend towards increased use of crystal methamphetamine in controls may be suggestive that participants using less hydromorphone but who substitute with other agents, may be at lower risk of IE. Similarly, we did not see a significant protective effect of always heating hydromorphone-CR preparations (OR 0.6; 95% CI 0.24-1.51), although this as well may have been due to an inadequate sample size.

While this study-- based on direct interviews-- did not find a relationship between hydromorphone-CR and IE, our previous work has demonstrated evidence of such a relationship. Our population-wide study in Ontario with over 60,000 PWID showed a 3.3 fold higher risk of acquiring IE within 120 days when prescribed hydromorphone-CR compared with other opioids (p<0.0001)(24). Moreover, we have also shown that drug excipients within hydromorphone-CR preserve S. aureus survival in vitro (12). This was not the case for immediate release hydromorphone or controlled-release Oxycodone(12). Furthermore, we found that the injectate obtained from aspirating from equipment previously used to inject hydromorphone-CR was contaminated with S. aureus in 14% of cases and thus injection of this drug would commonly be associated with bacteremia(12). The protective effect of using a lighter to pulverize drugs in this study may reflect a greater likelihood of heating preparations prior to injection due to the accessibility to a heating source. This practice has been shown to reduce bacterial load within cookers which contain hydromorphone-CR(12).

There has been very little data assessing the detailed injection practices associated with developing IE. The literature primarily studies the clinical and epidemiological characteristics of PWID developing IE(3,7,25–27). Some studies assessing injection practices of PWID are in relation to the development of skin and soft tissue infections(28) or infections in general(14,20,29). To our knowledge, this is the largest study (n=33) showcasing detailed survey data regarding injection practices of PWID with IE. Understanding PWID-IE risk factors are of importance to inform public health authorities in development of harm reduction strategies reducing infections in this at-risk population. Our one-on-one surveys have allowed for the collection of comprehensive quantitative and qualitative data to thoroughly understand injection practices and behaviours of PWID in our region, in an effort to elucidate the etiology of our high IE rates.

Previous studies suggested that IE in PWID was more frequently seen in males, younger patients and those with concurrent HIV infections(3,8,9). Our results show similar age distribution of IE, with it occurring in younger individuals (mean age 34). However, our cases and controls had similar concurrent HIV (OR 0.77; 95% CI 0.31-1.91) and HCV (OR 0.75; 95% CI 0.29-1.95) infections. Our high incidence of HIV in this population is likely related to our co-existent local HIV epidemic (19). Hepatitis C rates were based on self-report and a lack of awareness of status may have led to lower than expected rates in both cases and controls.

Unexpectedly, being a female PWID was a risk factor for IE in our population (OR 3.63; 95% CI 1.58-8.36). Wurcel et al. also showed a greater parity in PWID-IE distribution by sex (female = 53%) between the ages of 15-34 over a 13-year review of IE hospitalizations in the United States(5). We suspect that, gender differences may exist with regards to injection technique. Women are more likely to have sex partners that initiate them into injection practices and are more likely to share IPDE than men(30,31). Women can be identified sub-populations for targeted harm reduction and in particular, interventions should account for intimate partner dynamics concerning high-risk practices(32). Furthermore, female anatomy increases the difficulty of IVDU. We hypothesize that women have smaller veins may be difficult to visualize, often requiring increased manipulation during injections. This inability to find an adequate injection site with smaller veins can promote the usage of larger, more accessible central veins like the internal jugular, which further increase risks of infection. Additionally, local surveys in our region from the Middlesex-London Health Unit found that female PWID in London were more likely to borrow and share their IDPE(33). It was also anecdotally noted that women were less likely to access supervised injection sites, leading to unsafe injection practices that place them at risk of IE.

Homelessness and unstable housing have been associated with injecting in public spaces and other high-risk injection practices(34,35). However, in our study, cases (PWID IE+) were more likely to have stable housing compared to controls. This is supported by Roy et a.l(16), who found that unstable housing was not associated with conducting multiple washes (utilizing residual drug for multiple injections), which is often the preparatory method used to inject prescription opioids, such as hydromorphone-CR. We hypothesize that PWID using hydromorphone-CR, which is a more costly illicit substance, can be associated with stable housing, which is reflective of financial stability. Hydromorphone is one of the most expensive prescription opioids to purchase illicitly, costing $5.57CAN/mg ($4.28 US/mg) or $100.26 CAN for an 18 mg capsule(36).

Interestingly, we found that our cases were more likely to have completed secondary or post-secondary education (61.3% cases vs 33.7% controls). This is in contrast to studies linking incompletion of education with illicit substance use(37). Higher education likely is correlated with income and again may reflect greater accessibility to expensive prescription opiates.

Usage of provincial distributed IDPE, i.e. the Stericup for mixing drugs was found to be protective against IE. PWID who are more likely to use equipment from needle exchange programs are also more likely to be exposed to education on safe injection practices and consistently use sterile equipment. PWID with IE were also more likely to use objects for mixing and heating drugs that were not distributed through IDPE kits or commonly listed in our interview questions. This suggests that cases might be injecting in severe withdrawal states, where concern for safe practices do not take precedence over the need to use. Additionally, the increased use of a lighter may be suggestive that controls are using drugs that require heating such as heroin, crystal methamphetamine and cocaine, and these may reflect lower risk of using hydromorphone-CR.

Another risk factor for IE was the site used for injection. Entrenched drug users tend to have thickened scar tissue from chronic injections in the same location, in many cases this will be near the veins of the arm(38). Consequently, cases tended to inject in the feet, neck and breast tissue. We suspect that the association of using alternative sites of injection and IE likely reflects the greater difficulty in accessing common sites and that alternate sites have a greater likelihood of contamination. Uncommon injection sites may be a surrogate marker for more venous damage from previous injections and thus entrenched drug use(29). In particular, one study of PWID in the UK found the high-risk practice of injecting into the jugular vein was associated with the female gender and multiple body-site injections(29). Our study had similar findings since the PWID who developed IE in our region were more likely to be female and inject in multiple sites.

Case-control study design may lead to recall biases with cases more likely to recall perceived hazardous behaviours. Our study reviewed cases admitted to or transferred (due to IE complexity) to the hospitals in the city of London. We did not capture cases admitted to regional or rural sites as other research has found poor harm reduction practises prevalent in rural settings(20). Our controls were PWID accessing community resources as well as those presenting to outpatient clinics for other infectious complications. We did not capture PWID that do not seek medical or community supports, potentially missing controls who inject only at home, are not actively followed for their addiction disorders or are of high Socio-Economic status. These patients may therefore be less likely to perform high risk behaviours. In particular using the provincially distributed harm reduction materials may have been more common due to the controls having more access to these as many were attending addiction services centers. Providing a monetary compensation for participation could have compromised the integrity of participant responses received, although the relatively modest funds given in this study make this less likely. Finally, the relatively small sample size limited our ability to identify several hypothesized relationships. Further larger studies would be helpful.

This pilot study did not find an association between hydromorphone-CR use and infective endocarditis. The very high prevalence of hydromorphone-CR use in London made our sample size too small to identify a significant association. Being a female PWID and using alternative sites for injecting were risk factors for developing IE. Distribution of clean injection materials is protective for IE, supporting the necessity of harm reduction equipment distribution programs in reducing infectious complications among PWID. Further study of the risk factors for developing IE are warranted.

IE - infective endocarditis

PWID - people who inject drugs

IVDU - intravenous drug use

Hydromorphone-CR - hydromorphone controlled-release

IPDE - injection drug preparation equipment

STROBE - Strengthening the Reporting of Observational Studies in Epidemiology

Ethics approval and consent to participate

The study protocol was approved by an institutional board review (Health Sciences Research Ethics Board, Western University). Written informed consent was obtained from all participants. Participants were compensated with a CAD$10 Tim Horton’s coffee shop gift card.

Consent for publications

All authors consent to the publication of this manuscript. We had obtained written consent from participants which included the dissemination of the collected data.

Availability of the data and materials

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing Interests N/A

Funding This work was supported by an unrestricted grant from Ontario HIV Treatment Network and the St. Joseph’s Hospital Foundation.

Author’s Contributions

Meera Shah, Ryan Wong and Dr. Silverman had full access to all of the data in the study and take

responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Shah, Wong, Ball & Silverman.

Acquisition, analysis, or interpretation of data: Shah, Wong, Ball, Tan, Shojaei, Koivu and Silverman

Drafting of the manuscript: Shah, Wong, Silverman

Critical revision of the manuscript for important intellectual content: Koivu and Silverman

Statistical analysis: Shah, Wong and Tan

Obtained funding: Silverman.

Administrative, technical, or material support: Shah, Wong and Shojaei

Supervision: Silverman

Acknowledgements

We would like to acknowledge the Summer Research Training Program and the Dean’s Undergraduate Research Opportunities Program at the Schulich School of Medicine and Dentistry to financially support Meera Shah’s, Laura Ball’s and Ryan Wong’s involvement in the project. We also would like to thank our community members for being interested and willing to participate in research in efforts to improve the infectious disease health of our citizens.

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Table 1: Demographic characteristics and previous complications of PWID stratified by endocarditis history.
Variable (%)	Control (n=102) (%)	Case (n=33) (%)	p value
*Demographical Characteristics*
Female	21/102 (20.6)	16/33 (48.5)	0.002
Mean Age (years, std dev)	40.0 (11.0)	35.5 (9.4)
Caucasian	74/102 (72.5)	28/33 (84.8)
Stable Housing	45/102 (41.6)	12/33 (53.1)
Completion of secondary or post-secondary	31/92 (33.7)	19/31 (61.3)	0.01
Employed or seasonally employed	6/100 (6.0)	3/30 (10.0)
HIV	30/102 (29.4)	8/33 (24.2)
Hepatitis C	25/102 (24.5)	7/33 (21.2)
*Previous Complications*
Cellulitis	67/101 (66.3)	20/32 (60.6)
Cotton Fever	84/101 (83.2)	24/32 (75.0)
Osteomyelitis	7/101 (6.9)	3/32 (9.4)
Pneumonia	39/101 (38.6)	17/31 (54.8)

std dev: standard deviation

Table 2: Summary of PWID intravenous drug use stratified by endocarditis history.
Variable (%)	Control (n=102) (%)	Case (n=33) (%)	P value
*Drug Injected*
Oxycodone Hydrochloride tablets (Oxycontin)	43 (42.2)	10 (30.3)
Hydromorphone controlled-release capsules (Hydromorph Contin)	83 (81.4)	30 (90.9)	0.197
Crystal Methamphetamine	80 (78.4)	18 (54.5)	0.07
Hydromorphone controlled-release tablets (Dilaudid)	76 (74.5)	21 (63.6)	0.227
Bupropion (Wellbutrin)	0 (0)	1 (3)
Methylphenidate (Ritalin)	18 (17.6)	4 (12.1)
Cocaine	16 (15.7)	3 (9.1)
Crack	8 (7.8)	0
Fentanyl Patch	1 (1.0)	3 (9.1)
Fentanyl Tablet	4 (3.9)	1 (3.0)
Heroin	14 (13.7)	4 (12.1)
*Injection Location Most Frequently Used*
Arm	61 (59.8)	13 (39.4)	0.06
Hand	11 (10.8)	6 (18.2)
Wrist	3 (2.9)	1 (3.0)
Neck	18 (17.6)	5 (15.2)
Leg*	9 (8.8)	6 (18.2)
Foot	4 (3.9)	2 (6.1)
Multiple Sites**	6 (5.9)	7 (21.2)	*0.009*
Injection Location Used in the Past 3 Months	n=101	n=32
Hand***	78 (78.8)	21 (65.6)
Lower Leg	36 (36.0)	18 (54.5)
Femoral Vein	14 (13.9)	6 (18.2)
Feet	37 (36.6)	19 (57.6)	*0.034*
Groin	9 (8.9)	6 (18.2)
Neck	46 (46)	21 (63.6)	0.079
Breast (chest/pectoral)	0 (0)	2 (6.7)	0.077
Leg includes injection into the femoral vein and calf * Many different sites used
**Note all hand patients used arm in the last 3 months

Table 3: Summary of PWID intravenous drug use behaviours stratified by endocarditis history.
Variable (%)	Control (%)	Case (%)	P value
*Cooker Use*
Uses cooker with all drugs	60 /101 (59.4)	17/33 (51.5)
Uses a Stericup	84/102 (84.2)	14/33 (42.4)	<0.001
Unknown* cooker type	12/102 (11.8)	16/33 (48.5)	<0.001
*Heating*
Heats drugs in cookers (any drug)	70/101 (68.6)	28/33 (84.2)	0.069
Always heats hydromorphone-CR	31/82 (37.8)	8/30 (26.7)	0.38
Always or sometimes heats hydromorphone-CR and its subsequent washes	43/82 (52.4)	14/30 (46.7)
*Preparation*
Soaks drugs before injection	45/99 (45.5)	14/30 (46.7)
Reuse of hydromorphone-CR for a second wash	76/102 (74.5)	29/33 (87.9)	0.108
*Filter Use*
Cellulose filter used	97/101 (96.0)	31/32 (96.9)
Cigarette filter used	84/101 (83.2)	24/32 (75.0)
Reuses filters	65/102 (63.7)	20/33 (60.6)
Store filter in cooker	26/102 (25.5)	21/33 (36.4)
Store filter in pockets/body temperature	31/102 (30.4)	9/33 (28.1)
Shares filters	18/100 (18.0)	5/32 (15.6)
*Cleaning*
Cleans skin with alcohol swab before injection	69/74 (93.2)	18/20 (90.0)
Always cleans with alcohol swab before injection	33/74 (44.6)	5/20 (25.0)
Always cleans with alcohol swab and heats drug before injection	49/74 (66.2)	10/20 (50.0)
*Crushers*
Pill grinder	16/102 (15.7)	4/33 (12.1)
Lighter	60/102 (58.8)	12/33 (36.4)	*0.025*
Sharing crushers	36/97 (37.1)	14/29 (48.3)
*Needles*
Reuse of needles	76/102 (74.5)	23/33 (69.7)
Sharing of needles	24/102 (23.5)	4/33 (12.1)
Reuse of syringe barrel	68/102 (66.7)	20/33 (60.6)
* refers to cookers that were not Stericups, spoons, glass bottles or shot glasses

Table 4: Microbial etiology and site of endocardial involvement in PWID with IE.
Endocarditis Characteristics
Variable (%)	n=33
Organism
MSSA	23 (69.7%)
MRSA	5 (15.1%)
Enterococci	2(6.0%)
Other	3(9.1%)
Infected Valve
Tricuspid	24 (72.7%)
Pulmonic	0 (0%)
Mitral	6 (18.1%)
Aortic	2 (6.0%)
Unknown	1(3%)

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published 05 Jun, 2020

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Editorial decision: Major revision
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Risk Factors Of Infective Endocarditis In Persons Who Inject Drugs

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