Proteolytic Activities Expressed by Gastrointestinal Pathogens Bacillus cereus, Listeria monocytogenes and Enterococcus faecium in Different Growth Phases

Comparative seropositivity of Listeria monocytogenes in the serum of pregnant women with and without a history of abortion by serological and culture methods

Objective

Listeria monocytogenes is a major cause of miscarriage and postpartum infections in infant. Determining antibody levels against listeriolysin O can be valuable for diagnosing both invasive listeriosis and febrile gastroenteritis. However, serological methods that detect antibodies against incomplete forms of listeriolysin O can be more specific. The objective of this study was to identify (Listeria monocytogenes) in the serum of pregnant women using serological and culture methods.

Methods

Clinical samples (120 cases) were collected from pregnant women with a gestational age of less than 20 weeks. Diagnosis of Listeria monocytogenes was conducted using culture methods to identify anti-Listeria antibodies. Statistical analysis of the results was conducted using IBM SPSS Statistics version 23.0 (New York, USA), Pearson's Chi Square and fisher tests.

Results

The number of positive samples by culture and ELISA was 24.16% (29) and 28.3% (34), respectively. Out of the 29 positive sample by the culture method, 10 individuals had no abortion history, 16 and 3 individuals had 1 and 2 abortions and no sample had 3 abortions. Maybe, the more abortions a person has had, the less likely they are to be infected. In the Enzyme Linked Immuno-Sorbent Assay (ELISA) method, 13 individuals tested positive for both IgG and IgM antibodies and 38 individuals tested negative. Additionally, among the positive individuals with 1, 2, and 3 miscarriages, 0, 17, and 3 people were positive for the IgG antibody and 0, 18, and 3 individuals were positive for the IgM antibody. The analysis results indicated that there was no significant relationship between culture and abortion history (p = 0.316), IgG ELISA and history of miscarriage (p = 0.672) and IgM ELISA and history of miscarriage (p = 0.552).

Conclusion

There was no significant relationship between infection with Listeria monocytogenes and abortion (p ⩾ 0.05) in our samples. These results should be interpreted with caution due to the limitation of our small sample size.

Inhibition of Collagenase Q1 of Bacillus cereus as a Novel Antivirulence Strategy for the Treatment of Skin-Wound Infections

Despite the progress in surgical techniques and antibiotic prophylaxis, opportunistic wound infections with Bacillus cereus remain a public health problem. Secreted toxins are one of the main factors contributing to B. cereus pathogenicity. A promising strategy to treat such infections is to target these toxins and not the bacteria. Although the exoenzymes produced by B. cereus are thoroughly investigated, little is known about the role of B. cereus collagenases in wound infections. In this report, the collagenolytic activity of secreted collagenases (Col) is characterized in the B. cereus culture supernatant (csn) and its isolated recombinantly produced ColQ1 is characterized. The data reveals that ColQ1 causes damage on dermal collagen (COL). This results in gaps in the tissue, which might facilitate the spread of bacteria. The importance of B. cereus collagenases is also demonstrated in disease promotion using two inhibitors. Compound 2 shows high efficacy in peptidolytic, gelatinolytic, and COL degradation assays. It also preserves the fibrillar COLs in skin tissue challenged with ColQ1, as well as the viability of skin cells treated with B. cereus csn. A Galleria mellonella model highlights the significance of collagenase inhibition in vivo.

The proteolytic activity of Listeria monocytogenes HtrA

Background

High temperature requirement A (HtrA) is a widely expressed chaperone and serine protease in bacteria. HtrA proteases assemble and hydrolyze misfolded proteins to enhance bacterial survival under stress conditions. Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen that induces listeriosis in humans. In previous studies, it was shown that deletion of htrA in the genome of L. monocytogenes increased the susceptibility to cellular stress and attenuated virulence. However, expression and protease activity of listerial HtrA (LmHtrA) were never analyzed in detail.

Results

In this study, we cloned LmHtrA wildtype (LmHtrA^wt) and generated a proteolytic inactive LmHtrA^SA mutant. Recombinant LmHtrA^wt and LmHtrA^SA were purified and the proteolytic activity was analyzed in casein zymography and in vitro cleavage assays. LmHtrA activity could be efficiently blocked by a small molecule inhibitor targeting bacterial HtrA proteases. The expression of LmHtrA was enhanced in the stationary growth phase of L. monocytogenes and significantly contributed to bacterial survival at high temperatures.

Conclusions

Our data show that LmHtrA is a highly active caseinolytic protease and provide a deeper insight into the function and mechanism, which could lead to medical and biotechnological applications in the future.

A Clinicopathological Analysis of Six Autopsy Cases of Sudden Unexpected Death due to Infectious Aortitis in Patients with Aortic Tears

Objective Cardiovascular disease is a leading cause of sudden unexpected death even in hospitalized patients. Infectious aortitis is a rare disease that has the potential to cause aortic tears and hemorrhage followed by sudden death. The aim of this study was to reveal the clinicopathological features of infectious aortitis that are related to sudden unexpected death. Methods We retrospectively reviewed 1,310 autopsy cases over 15 years and selected the cases involving patients who died suddenly due to aortic tears. We analyzed the clinical information and pathological findings. Results One hundred thirty-three of 1,310 cases (10.2%) were autopsied under the clinical diagnosis of unexpected sudden death. Aortic tears were identified in 33 cases (2.5%) and infectious aortitis was diagnosed in 6 (18.2%) of these cases. All cases involved male patients (middle-aged to elderly) with risk factors for atherosclerosis (i.e., hypertension). The laboratory data showed continuous leukocytosis and C-reactive protein elevation, even during the improvement phase, in patients with pre-existing infectious disease. The autopsy findings revealed three types of aortic tears (aneurysms, dissections and penetrating atherosclerotic ulcers with moderate to severe atherosclerosis), and the infiltration of numerous neutrophils at the site of rupture. Gram-positive bacteria were detected in four cases and Gram-negative bacteria were detected in two cases. Discussion We demonstrated that sudden unexpected death caused by infectious aortitis rarely occurred in hospitalized patients, even in the recovery phase of the preceding infectious disease. We therefore recommend that clinicians pay attention to infectious aortitis in patients with infectious disease, particularly elderly patients with atherosclerotic disease, even those who are in the improvement phase. Conclusion Unexpected sudden death by infectious aortitis in the recovery phase of antecedent infection.

Effect of Modified Pulsatilla Powder on Enterotoxigenic Escherichia coli O101-Induced Diarrhea in Mice

MPP can be effective in the treatment of E. coli O101-induced diarrhea in mice. MPP can improve the weight loss caused by diarrhea, increase spleen and thymus indices, and reduce the diarrhea index. MPP can reduce the number of WBC, regulate the level of cytokines, and regulate the intestinal microbial flora. These data suggest that MPP is a promising candidate for treatment of E. coli-induced diarrhea in humans and animals.

Cloning, Purification and Characterization of the Collagenase ColA Expressed by Bacillus cereus ATCC 14579

Bacterial collagenases differ considerably in their structure and functions. The collagenases ColH and ColG from Clostridium histolyticum and ColA expressed by Clostridium perfringens are well-characterized collagenases that cleave triple-helical collagen, which were therefore termed as ´true´ collagenases. ColA from Bacillus cereus (B. cereus) has been added to the collection of true collagenases. However, the molecular characteristics of B. cereus ColA are less understood. In this study, we identified ColA as a secreted true collagenase from B. cereus ATCC 14579, which is transcriptionally controlled by the regulon phospholipase C regulator (PlcR). B. cereus ATCC 14579 ColA was cloned to express recombinant wildtype ColA (ColA^wt) and mutated to a proteolytically inactive (ColA^E501A) version. Recombinant ColA^wt was tested for gelatinolytic and collagenolytic activities and ColA^E501A was used for the production of a polyclonal anti-ColA antibody. Comparison of ColA^wt activity with homologous proteases in additional strains of B. cereus sensu lato (B. cereus s.l.) and related clostridial collagenases revealed that B. cereus ATCC 14579 ColA is a highly active peptidolytic and collagenolytic protease. These findings could lead to a deeper insight into the function and mechanism of bacterial collagenases which are used in medical and biotechnological applications.