Epidemiological findings and medical, legal, and public health challenges of an investigation of severe soft tissue infections and deaths among injecting drug users -- Ireland, 2000

Experimental identification and computational characterization of a novel extracellular metalloproteinase produced by Clostridium sordellii

The open (white, green) vs. closed (purple, cyan) structures of Clostridium sordellii metalloproteinase.

Clostridium sordellii is a lethal pathogen for both animals and humans. Severe capillary leakage, toxic shock syndrome, and an extreme leukemoid reaction (LR), are hallmark features of C. sordellii infections and contribute to its high mortality rate. Here we report the discovery of a previously unknown and uncharacterized metalloproteinase of C. sordellii (referred as Mcs1) that cleaves human vascular cell adhesion molecule (VCAM)-1 in vitro, an adhesion molecule critical to hematopoietic precursor retention and leukocyte diapedesis. We successfully identified the open reading frame encoding Mcs1 within the ATCC 9714 genome and developed an Δmcs1 mutant strain using the ClosTron mutagenesis technology. No VCAM-1 proteolysis was observed from exotoxins collected from mutant strain cultures. Using advanced protein structural modeling and molecular dynamics simulation techniques, the 3D molecular structure and conformational features of Mcs1 were also characterized. Our data demonstrates that Mcs1 proteolytic activity is controlled by the electrostatic interactions between Glu113 and Arg227 residues and the gating motions within its cleft region. This pilot interdisciplinary investigation provided crucial experimental evidence of the existence of Mcs1 in C. sordellii and molecular insights into its 3D structure and proteolytic activity. These findings have the potential to help advance new therapeutics and diagnostics against deadly C. sordellii infections. Follow-up in vitro and in vivo work is under way to further characterize Mcs1 enzymatic kinetics and its role in C. sordellii pathogenesis.

Surveillance of injecting-related injury and diseases in people who inject drugs attending a targeted primary health care facility in Sydney's Kings Cross

OBJECTIVE

This study examined the prevalence of injecting-related injuries and diseases (IRIDs) and associated risk factors among people who inject drugs (PWID) attending a primary health care facility in Sydney's Kings Cross.

METHODS

We calculated prevalence of a wide range of IRIDs utilising data reported by 702 PWID who completed a clinician-administered survey at their first visit. Multivariable logistic regressions identified factors independently associated with at least one episode of: i) cutaneous and ii) non-cutaneous IRIDs.

RESULTS

Lifetime prevalence of cutaneous IRIDs was 23%. Forty-two per cent of PWID with a history of abscess attended hospital at their most recent episode. Female gender, lifetime receptive syringe sharing (RSS), injecting while in custody, and ever injecting in places other than the arm were independently associated with reporting at least one episode of cutaneous IRIDs. Ever injecting in sites other than the arm, injecting for five or more years and lifetime history of RSS were independently associated with at least one episode of non-cutaneous IRIDs.

CONCLUSIONS

IRIDs are a substantial health issue for PWID. Their ongoing surveillance is warranted particularly in primary care settings targeting PWID to inform prevention and early management, thus reducing complications that may require hospital admission.

Whole genome protein microarrays for serum profiling of immunodominant antigens of Bacillus anthracis

A commercial Bacillus anthracis (Anthrax) whole genome protein microarray has been used to identify immunogenic Anthrax proteins (IAP) using sera from groups of donors with (a) confirmed B. anthracis naturally acquired cutaneous infection, (b) confirmed B. anthracis intravenous drug use-acquired infection, (c) occupational exposure in a wool-sorters factory, (d) humans and rabbits vaccinated with the UK Anthrax protein vaccine and compared to naïve unexposed controls. Anti-IAP responses were observed for both IgG and IgA in the challenged groups; however the anti-IAP IgG response was more evident in the vaccinated group and the anti-IAP IgA response more evident in the B. anthracis-infected groups. Infected individuals appeared somewhat suppressed for their general IgG response, compared with other challenged groups. Immunogenic protein antigens were identified in all groups, some of which were shared between groups whilst others were specific for individual groups. The toxin proteins were immunodominant in all vaccinated, infected or other challenged groups. However, a number of other chromosomally-located and plasmid encoded open reading frame proteins were also recognized by infected or exposed groups in comparison to controls. Some of these antigens e.g., BA4182 are not recognized by vaccinated individuals, suggesting that there are proteins more specifically expressed by live Anthrax spores in vivo that are not currently found in the UK licensed Anthrax Vaccine (AVP). These may perhaps be preferentially expressed during infection and represent expression of alternative pathways in the B. anthracis “infectome.” These may make highly attractive candidates for diagnostic and vaccine biomarker development as they may be more specifically associated with the infectious phase of the pathogen. A number of B. anthracis small hypothetical protein targets have been synthesized, tested in mouse immunogenicity studies and validated in parallel using human sera from the same study.

View from the front lines: an emergency medicine perspective on clostridial infections in injection drug users

Injection drug use (IDU), specifically non-intravenous "skin-popping" of heroin, seems to provide optimal conditions for Clostridial infection and toxin production. IDU is therefore a major risk factor for wound botulism and Clostridial necrotizing soft tissue infections (NSTI) and continues to be linked to cases of tetanus. Case clusters of all 3 diseases have occurred among IDUs in Western U.S. and Europe. Medical personnel who care for the IDU population must be thoroughly familiar with the clinical presentation and management of these diseases. Wound botulism presents with bulbar symptoms and signs that are easily overlooked; rapid acquisition and administration of antitoxin can prevent neuromuscular respiratory failure. In addition to Clostridium perfringens, IDU-related NSTIs can be caused by Clostridium sordellii and Clostridium novyi, which may share a distinct clinical presentation. Early definitive NSTI management, which decreases mortality, requires a low index of suspicion on the part of emergency physicians and low threshold for surgical exploration and debridement on the part of the surgeon. Tetanus should be preventable in the IDU population through careful attention to vaccination status.

Health Security and Disease Detection in the European Union

In a globalised world, national and international institutions in charge of health security can no longer only rely on traditional disease reporting mechanisms, not designed to recognise emergence of new hazards. New approaches are developing to improve the capacity of surveillance systems in detecting previously unknown threats. More recently, surveillance institutions have been actively searching for information about health threats using internet scanning tools, email distribution lists or networks that complement the early warning function of routine surveillance systems. Since its foundation, ECDC has developed an epidemic intelligence framework that encompasses all activities related to early identification of potential health hazards, their verification, assessment and investigation, in order to recommend public health control measures. Since June 2005, about 900 threats have been monitored by ECDC. Several threats made it necessary to develop formal risk assessments or to dispatch ECDC experts to outbreak areas. Examples of recent events, identified through the epidemic intelligence activity, are presented to illustrate the course of action from threat detection through risk management in Europe.

Treatment of medical, psychiatric, and substance-use comorbidities in people infected with HIV who use drugs

HIV-infected drug users have increased age-matched morbidity and mortality compared with HIV-infected people who do not use drugs. Substance-use disorders negatively affect the health of HIV-infected drug users, who also have frequent medical and psychiatric comorbidities that complicate HIV treatment and prevention. Evidence-based treatments are available for the management of substance-use disorders, mental illness, HIV and other infectious complications such as viral hepatitis and tuberculosis, and many non-HIV-associated comorbidities. Tuberculosis co-infection in HIV-infected drug users, including disease caused by drug-resistant strains, is acquired and transmitted as a consequence of inadequate prescription of antiretroviral therapy, poor adherence, and repeated interfaces with congregate settings such as prisons. Medication-assisted therapies provide the strongest evidence for HIV treatment and prevention efforts, yet are often not available where they are needed most. Antiretroviral therapy, when prescribed and adherence is at an optimum, improves health-related outcomes for HIV infection and many of its comorbidities, including tuberculosis, viral hepatitis, and renal and cardiovascular disease. Simultaneous clinical management of multiple comorbidities in HIV-infected drug users might result in complex pharmacokinetic drug interactions that must be adequately addressed. Moreover, interventions to improve adherence to treatment, including integration of health services delivery, are needed. Multifaceted, interdisciplinary approaches are urgently needed to achieve parity in health outcomes in HIV-infected drug users.

Clostridium sordellii infection: epidemiology, clinical findings, and current perspectives on diagnosis and treatment

Clostridium sordellii infections pose difficult clinical challenges and are usually fatal. Most commonly, these infections occur after trauma, childbirth, and routine gynecological procedures, but they have recently been associated with medically induced abortions and injection drug use. We report 2 fatal cases, one of which was associated with minor trauma, and the other of which was associated with normal childbirth, and we summarize the clinical features of 43 additional cases of reported C. sordellii infection. Of these 45 cases, 8 (18%) were associated with normal childbirth, 5 (11%) were associated with medically induced abortion, and 2 (0.4%) were associated with spontaneous abortion. The case-fatality rate was 100% in these groups. Ten (22%) of the C. sordellii infections occurred in injection drug users, and 50% of these patients died. Other cases of C. sordellii infection (in 19 patients [43%]) occurred after trauma or surgery, mostly in healthy persons, and 53% these patients died. Overall, the mortality rate was 69% (31 of 45 patients). Eighty-five percent of all patients with fatal cases died within 2-6 days of initial infection, and nearly 80% of fatal cases developed leukemoid reactions. Rapid diagnostic tests and improved treatments are needed to reduced the morbidity and mortality associated with this devastating infection.