Deaths from Clostridium sordellii after medical abortion

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.

A novel murine model of Clostridium sordellii myonecrosis: Insights into the pathogenesis of disease

Clostridium sordellii infections have been reported in women following natural childbirth and spontaneous or medically-induced abortion, injection drug users and patients with trauma. Death is rapid and mortality ranges from 70 to 100%. Clinical features include an extreme leukemoid reaction, the absence of fever, and only minimal pain or erythema at the infected site. In the current study, we developed a murine model of C. sordellii soft tissue infection to elucidate the pathogenic mechanisms. Mice received 0.5, 1.0 or 2.0 × 10(6) CFU C. sordellii (ATCC 9714 type strain) in the right thigh muscle. All doses caused fatal infection characterized by intense swelling of the infected limb but no erythema or visible perfusion deficits. Survival rates and time to death were inoculum dose-dependent. Mice developed a granulocytic leukocytosis with left shift, the onset of which directly correlated with disease severity. Histopathology of infected tissue showed widespread edema, moderate muscle damage and minimal neutrophil infiltration. Circulating levels of granulocyte colony-stimulating factor (G-CSF), soluble tumor necrosis factor receptor I (sTNF-RI) and interlukin-6 (IL-6) were significantly increased in infected animals, while TNF-α, and IL-1β levels were only mildly elevated, suggesting these host factors likely mediate the leukocytosis and innate immune dysfunction characteristic of this infection. Thus, this model mimics many of the salient features of this infection in humans and has allowed us to identify novel targets for intervention.

Hypotension after medical termination of pregnancy: think outside of the uterus

BACKGROUND

Under usual circumstances, an ectopic pregnancy would not be generally considered in the initial differential diagnosis of shock after voluntary termination of pregnancy.

OBJECTIVE

To present a rare case of a young woman with shock after voluntary termination of pregnancy due to undiagnosed ectopic pregnancy with concealed hemorrhage.

CASE REPORT

A 37-year-old woman presented to the Emergency Department (ED) 3 days after termination of pregnancy with clinical features of shock. The patient had some evidence of infection and was initially managed as a case of septic shock secondary to possible complication of recent termination of pregnancy. Subsequent work-up led to suspicion of internal bleeding, and ruptured ectopic pregnancy was confirmed and managed successfully.

CONCLUSION

Ruptured ectopic pregnancy can present with a wide range of symptoms and under variable circumstances. Recognition of subtle signs of hemorrhage and consideration of the diagnosis of ruptured pregnancy in the ED will lead to early diagnosis and appropriate management.