Objectification of evaluation criteria in microscopic agglutination test using deep learning.

We aim to objectify the evaluation criteria of agglutination rate estimation in the Microscopic Agglutination Test (MAT). This study proposes a deep learning method that extracts free leptospires from dark-field microscopic images and calculates the agglutination rate. The experiments show the effect of objectification with real pictures.

Insufficient anti-spike RBD IgA responses after triple vaccination with intramuscular mRNA BNT162b2 vaccine against SARS-CoV-2.

Objectives: This study aims to examine whether the parenterally administered mRNA-based COVID-19 vaccines can induce sufficient mucosal-type IgA responses to prevent SARS-CoV-2 transmission. Methods: We examined the longitudinal kinetics of SARS-CoV-2 spike RBD-specific IgA and IgG responses in sera of Japanese healthcare workers (HCWs) after receiving two doses and the third dose of BNT162b2 mRNA vaccines. During the prospective cohort study, Omicron breakthrough infections occurred in 62 participants among 370 HCWs who had received triple doses of the vaccine. Pre-breakthrough sera of infected HCWs and non-infected HCWs were examined for the levels of anti-RBD IgA and IgG titers. Results: The seropositivity of anti-RBD IgA at 1 M after the second vaccine (2D-1M) and after the third dose (3D-1M) was 65.4% and 87.4%, respectively, and wanes quickly. The boosting effect on anti-RBD Ab titers following breakthrough infections was more notable for anti-RBD IgA than for IgG. There were partial cause-relationships between the lower anti-RBD IgA or IgG at pre-breakthrough sera and the breakthrough infection. Conclusions: Parenterally administered COVID-19 vaccines do not generate sufficient mucosal-type IgA responses despite strong systemic IgG responses to SARS-CoV-2. These results demonstrate the necessity and importance of reevaluating vaccine design and scheduling to efficiently increase oral or respiratory mucosal immunity against SARS-CoV-2.

The appearance of anti-spike receptor binding domain immunoglobulin G4 responses after repetitive immunization with messenger RNA-based COVID-19 vaccines.

OBJECTIVES: It is crucial to analyze the consequences of repeated messenger RNA (mRNA)-based COVID-19 vaccinations on SARS-CoV-2 spike receptor binding domain (RBD)-specific immunoglobulin (Ig)G subclass and the possible causal relationship with breakthrough infection. METHODS: We examined the longitudinal kinetics of RBD-specific IgG subclass antibodies in sera after receiving the second, third, and fourth doses of mRNA-based COVID-19 vaccines in Japanese healthcare workers. Anti-RBD IgG subclass in sera of patients with COVID-19-infected who had not received the COVID-19 vaccine were also examined. We compared anti-RBD IgG subclass antibody titers in the serum of pre-breakthrough-infected vaccinees and non-infected vaccinees. RESULTS: The seropositivity of anti-RBD IgG4 after the vaccination was 6.76% at 1 month after the second dose, gradually increased to 50.5% at 6 months after the second dose, and reached 97.2% at 1 month after the third dose. The seropositivity and titers of anti-RBD IgG1/IgG3 quickly reached the maximum at 1 month after the second dose and declined afterward. The elevated anti-RBD IgG4 Ab levels observed after repeated vaccinations were unlikely to increase the risk of breakthrough infection. CONCLUSIONS: Repeated vaccinations induce delayed but drastic increases in anti-RBD IgG4 responses. Further functional investigations are needed to reveal the magnitude of the high contribution of spike-specific IgG4 subclasses after repeated mRNA-based COVID-19 vaccinations.

Multiple mutations of Mycobacterium intracellulare subsp. chimaera causing false-negative reaction to the transcription-reverse transcription concerted method for pathogen detection.

OBJECTIVES: To report an isolate of Mycobacterium intracellulare subsp. chimaera with multiple mutations in 16S ribosomal RNA (rRNA) gene, resulting in the false-negative reaction to the transcription-reverse transcription concerted (TRC) method for Mycobacterium avium-intracellulare complex. METHODS: We used TRC, polymerase chain reaction (PCR), and Matrix-assisted laser desorption/ionization Time-of-Flight/Mass Spectrometry (MALDI-TOF/MS) methods to identify a clinical isolate in 2021. Due to the discordant results between TRC and PCR or MALDI-TOF MS methods, 16S rRNA sequencing, whole-genome shotgun (WGS) sequencing, and average nucleotide identity (ANI) analysis were employed to identify the isolate. RESULTS: A mycobacterial isolate from a sputum sample gave negative results for the detection of Mycobacterium tuberculosis complex or M. avium-intracellulare complex by the TRC method. However, the isolate was identified as M. intracellulare by both PCR method and MALDI-TOF MS method. WGS sequencing of 16S rRNA genome revealed eight substitution mutations and one insertion mutation within the region, which could hamper the correct reaction to TRC method. Subsequent ANI analysis between the isolate and various species of nontuberculosis mycobacteria revealed that the isolate could be identified as M. intracellulare subsp. chimaera. CONCLUSION: Rare mutations within the 16S rRNA genome resulted in the false-negative identification of Mycobacterium chimaera by the TRC method. WGS sequencing and ANI analysis was necessary to identify the isolate.

Chlamydia pneumoniae Lung Infection in Mice Induces Fatty Acid-Binding Protein 4-Dependent White Adipose Tissue Pathology.

Fatty acid-binding protein 4 (FABP4) is a critical immune-metabolic modulator, mainly expressed in adipocytes and macrophages, secreted from adipocytes in association with lipolysis, and plays essential pathogenic roles in cardiovascular and metabolic diseases. We previously reported Chlamydia pneumoniae infecting murine 3T3-L1 adipocytes and causing lipolysis and FABP4 secretion in vitro. However, it is still unknown whether C. pneumoniae intranasal lung infection targets white adipose tissues (WATs), induces lipolysis, and causes FABP4 secretion in vivo. In this study, we demonstrate that C. pneumoniae lung infection causes robust lipolysis in WAT. Infection-induced WAT lipolysis was diminished in FABP4-/- mice or FABP4 inhibitor-pretreated wild-type mice. Infection by C. pneumoniae in wild-type but not FABP4-/- mice induces the accumulation of TNF-α- and IL-6-producing M1-like adipose tissue macrophages in WAT. Infection-induced WAT pathology is augmented by endoplasmic reticulum (ER) stress/the unfolded protein response (UPR), which is abrogated by treatment with azoramide, a modulator of the UPR. C. pneumoniae lung infection is suggested to target WAT and induce lipolysis and FABP4 secretion in vivo via ER stress/UPR. FABP4 released from infected adipocytes may be taken up by other neighboring intact adipocytes or adipose tissue macrophages. This process can further induce ER stress activation and trigger lipolysis and inflammation, followed by FABP4 secretion, leading to WAT pathology. A better understanding of the role of FABP4 in C. pneumoniae infection-induced WAT pathology will provide the basis for rational intervention measures directed at C. pneumoniae infection and metabolic syndrome, such as atherosclerosis, for which robust epidemiologic evidence exists.

Antibody acquisition after second and third SARS-CoV-2 vaccinations in Japanese kidney transplant patients: a prospective study.

BACKGROUND: Kidney transplant patients have lower antibody acquisition after SARS-CoV-2 vaccination. The efficacy of vaccines in Japanese kidney transplant patients with specific characteristics, such as predominant living-donor, ABO-incompatible kidney transplant, and low-dose immunosuppression, requires verification. METHODS: We conducted a prospective study to estimate anti-SARS-CoV-2 antibody levels in 105 kidney transplant patients and 57 controls. Blood samples were obtained before vaccination, 1, 3, and 6 months after second vaccination, and 1 month after third vaccination. We investigated antibody acquisition rates, antibody levels, and factors associated with antibody acquisition. RESULTS: One month after second vaccination, antibody acquisition was 100% in the controls but only 36.7% in the kidney transplant group (P < 0.001). Antibody levels in positive kidney transplant patients were also lower than in the controls (median, 4.9 arbitrary units vs 106.4 arbitrary units, respectively, P < 0.001). Years after kidney transplant (odds ratio 1.107, 95% confidence interval 1.012-1.211), ABO-incompatible kidney transplant (odds ratio 0.316, 95% confidence interval 0.101-0.991) and mycophenolate mofetil use (odds ratio 0.177, 95% confidence interval 0.054-0.570) were significant predictors for antibody acquisition after second vaccination. After third vaccination, antibody positivity in the kidney transplant group increased to 75.3%, and antibody levels in positive patients were 71.7 arbitrary units. No factors were associated with de novo antibody acquisition. CONCLUSIONS: In Japanese kidney transplant patients, years after kidney transplant, ABO-incompatible kidney transplant and mycophenolate mofetil use were predictors for antibody acquisition after second vaccination. Third vaccination improves antibody status even in patients who were seronegative after the second vaccination.

A fatal case of hemophagocytic lymphohistiocytosis associated with gestational psittacosis without symptoms of pneumonia.

Psittacosis is a zoonotic infection caused by Chlamydia psittaci. Most patients present with acute respiratory symptoms and systemic illness. When C. psittaci infects pregnant women, it causes severe clinical manifestations called gestational psittacosis. Here we report a case of gestational psittacosis. Our patient lacked respiratory symptoms, and pathological postmortem examinations revealed severe placentitis. Both DNA and immunohistochemical analyses were positive for C. psittaci from formalin-fixed paraffin-embedded tissues. The chlamydial DNA in the placenta was about 100 times more abundant than that in the lungs; therefore, the placenta rather than the lungs was the probable target of the C. psittaci infection during this pregnancy. We could not identify the source of infection. Gestational psittacosis should be considered in the differential diagnosis for fever of unknown origin during pregnancy, even in cases lacking respiratory symptoms.

Bortezomib Eliminates Persistent Chlamydia trachomatis Infection through Rapid and Specific Host Cell Apoptosis.

Chlamydia trachomatis, a parasitic intracellular bacterium, is a major human pathogen that causes millions of trachoma, sexually transmitted infections, and pneumonia cases worldwide. Previously, peptidomimetic inhibitors consisting of a hydrophobic dipeptide derivative exhibited significant inhibitory effects against chlamydial growth. Based on this finding, this study showed that both bortezomib (BTZ) and ixazomib (IXA), anticancer drugs characterized by proteasome inhibitors, have intensive inhibitory activity against Chlamydia. Both BTZ and IXA consisted of hydrophobic dipeptide derivatives and strongly restricted the growth of Chlamydia (BTZ, IC50 = 24 nM). In contrast, no growth inhibitory effect was observed for other nonintracellular parasitic bacteria, such as Escherichia coli. BTZ and IXA appeared to inhibit chlamydial growth bacteriostatically via electron microscopy. Surprisingly, Chlamydia-infected cells that induced a persistent infection state were selectively eliminated by BTZ treatment, whereas uninfected cells survived. These results strongly suggested the potential of boron compounds based on hydrophobic dipeptides for treating chlamydial infections, including persistent infections, which may be useful for future therapeutic use in chlamydial infectious diseases.

Longitudinal Dynamics of SARS-CoV-2 IgG Antibody Responses after the Two-Dose Regimen of BNT162b2 Vaccination and the Effect of a Third Dose on Healthcare Workers in Japan.

Analysis of longitudinal dynamics of humoral immune responses to the BNT162b2 COVID-19 vaccine might provide useful information to predict the effectiveness of BNT162b2 in preventing SARS-CoV-2 infection. Herein, we measure anti-RBD IgG at 1, 3 and 6 months (M) after the second dose of BNT162b2, and at 1 M after a third dose of BNT162b2 vaccination in 431 COVID-19-naïve healthcare workers (HCWs) in Japan. All HCWs mounted high-anti-RBD IgG responses after the two-dose regimen of BNT162b2 vaccinations. Older persons and males presented lower anti-RBD IgG responses than younger adults and females, respectively. The decay in anti-RBD IgG started from 1 M after the second dose of BNT162b2 and anti-RBD IgG titers dropped to nearly one-tenth at 6 M after the second vaccination. Subsequently, the participants received a third dose of BNT162b2 at 8 M after the second dose of BNT162b2 vaccine. Anti-RBD antibody titers 1 M after the third dose of BNT162b2 increased seventeen times that of 6 M after the second dose, and was twice higher than the peak antibody titers at 1 M after the second dose of vaccination. The negative effect of age for the male gender on anti-RBD IgG antibody titers was not observed at 1 M after the third dose of BNT162b2 vaccine. There were no notable adverse events reported, which required hospitalization in these participants. These results suggest that the third dose of BNT162b2 safely improves humoral immunity against SARS-CoV-2 with no major adverse events.

Co-infection of human papillomavirus and other sexually transmitted bacteria in cervical cancer patients in the Philippines.

Cervical cancer is the fourth most common cancer in women globally. Based on several epidemiologic studies, human papillomavirus is strongly associated with cervical neoplasia. Aside from HPV, other bacterial infections in the genital tract were associated with cervical neoplasia. This study aimed to determine the prevalence of HPV infection; and co-infection with Ureaplasma spp., Mycoplasma spp., Chlamydia trachomatis, and Neisseria gonorrheae in Filipino cervical cancer patients. Forty-four patients (28 patients with cervical carcinoma and 16 patients with non-malignant cervix) who consulted in the Philippine General Hospital from 2016 to 2017 were included in this study. HPV genotyping and genetic detection of Ureaplasma spp., Mycoplasma spp., C. trachomatis, and N. gonorrheae were done using different PCR assays. The prevalence of HPV 16/18/33/52 was 75% in cervical cancer patients and 25% in control patients. Infection with HPV 16/18/33/52 was significantly associated with having cervical cancer (OR: 9.00; 95% CI: 2.18-37.18; p = 0.0024). HPV-16 was the most prevalent HPV genotype among Filipino cervical cancer patients. HPV-18 and HPV-52 were only detected from cervical cancer patients. Among HPV-positive patients, we noted a 22.73% co-infection with Ureaplasma spp. and 9.09% co-infection with Mycoplasma spp. To our knowledge, this is the first study on the co-infection of HPV and sexually transmitted infections among cervical cancer patients in the Philippines.

Intracellular Survival of Biofilm-Forming MRSA OJ-1 by Escaping from the Lysosome and Autophagosome in J774A Cells Cultured in Overdosed Vancomycin.

We investigated the drug-resistant mechanisms of intracellular survival of methicillin-resistant S. aureus (MRSA). Our established MRSA clinical strain, OJ-1, with high biofilm-forming ability, and a macrophage cell line, J774A, were used. After ingestion of OJ-1 by J774A, the cells were incubated for ten days with vancomycin at doses 30 times higher than the minimum inhibitory concentration. The number of phagocytosed intracellular OJ-1 gradually decreased during the study but plateaued after day 7. In J774A cells with intracellular OJ-1, the expression of LysoTracker-positive lysosomes increased until day 5 and then declined from day 7. In contrast, LysoTracker-negative and OJ-1-retaining J774A cells became prominent from day 7, and intracellular OJ-1 also escaped from the autophagosome. Electron microscopy also demonstrated that OJ-1 escaped the phagosomes and was localized in the J774A cytoplasm. At the end of incubation, when vancomycin was withdrawn, OJ-1 started to grow vigorously. The present results indicate that intracellular phagocytosed biofilm-forming MRSA could survive for more than ten days by escaping the lysosomes and autophagosomes in macrophages. Intracellular MRSA may survive in macrophages, and accordingly, they could be resistant to antimicrobial drug treatments. However, the mechanisms their escape from the lysosomes are still unknown. Additional studies will be performed to clarify the lysosome-escaping mechanisms of biofilm-forming MRSA.

Emerging resistance to beta-lactams in Pantoea ananatis isolated from an immunocompetent patient with bacteremia.

We observed an emerging resistance to ß-lactams in a P. ananatis bacteremia case. Whole genome sequence analysis detected two ß-lactamase genes as well as related genes that regulate the ß-lactamase genes in the chromosome. The induction experiment resulted in the expression of the class A ß-lactamase gene in the isolate.

Epipharyngeal Abrasive Therapy Down-regulates the Expression of SARS-CoV-2 Entry Factors ACE2 and TMPRSS2.

BACKGROUND: The epipharynx, with its high expression of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) entry factors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2), is a primary target for SARS-CoV-2 replication in the early stage of Coronavirus Disease 19 (COVID-19). Epipharyngeal abrasive therapy (EAT) is a treatment for epipharyngitis in Japan which involves applying zinc chloride to the epipharyngeal mucosa. In this study, we evaluated the expression patterns of ACE2 and TMPRSS2 in tissue samples from patients before and after EAT. PATIENTS AND METHODS: The study subjects were seven patients that had not been treated with EAT and 11 patients that had. For immunohistochemical assessment of the epipharyngeal mucosa, the staining intensity of ACE2 and TMPRSS2 was described as an immunohistochemical score (IHC score). RESULTS: The IHC scores for ACE2 and TEMPRSS2 in the EAT-treated group were 3.40-fold and 1.81-fold lower, respectively, than those in the non-treated group (p=0.0208 and p=0.0244, respectively). CONCLUSION: EAT down-regulates the expression of SARS-CoV-2 entry factors ACE2 and TMPRSS2. Thus, EAT has potential as a novel COVID-19 preventative method.

Blockade of endoplasmic reticulum stress-induced cell death by Ureaplasma parvum vacuolating factor.

Previously, we found that Ureaplasma parvum internalised into HeLa cells and cytosolic accumulation of galectin-3. U. parvum induced the host cellular membrane damage and survived there. Here, we conducted vesicular trafficking inhibitory screening in yeast to identify U. parvum vacuolating factor (UpVF). U. parvum triggered endoplasmic reticulum (ER) stress and upregulated the unfolded protein response-related factors, including BiP, P-eIF2 and IRE1 in the host cells, but it blocked the induction of the downstream apoptotic factors. MicroRNA library screening of U. parvum-infected cells and UpVF-transfected cells identified miR-211 and miR-214 as the negative regulators of the apoptotic cascade under ER stress. Transient expression of UpVF induced HeLa cell death with intracellular vacuolization; however, some stable UpVF transformant survived. U. parvum-infected cervical cell lines showed resistance to actinomycin D, and UpVF stable transformant cell lines exhibited resistance to X-ray irradiation, as well as cisplatin and paclitaxel. UpVF expressing cervical cancer xenografts in nude mice also acquired resistance to cisplatin and paclitaxel. A mycoplasma expression vector based on Mycoplasma mycoides, Syn-MBA (multiple banded antigen)-UpVF, reduced HeLa cell survival compared with that of Syn-MBA after 72 hr of infection. These findings together suggest novel mechanisms for Ureaplasma infection and the possible implications for cervical cancer malignancy. TAKE AWAYS: • Ureaplasmal novel virulence factor, UpVF, was identified. • UpVF triggered ER stress but suppressed apoptotic cascade via miR-211 and -214. • UpVF conferred resistance to anticancer treatments both in vivo and in vitro. • Dual expression of MBA and UpVF in JCVI-syn3B showed host cell damage.

Development of risk factor-based scoring system for detection of hypervirulent Klebsiella pneumoniae bloodstream infections.

BACKGROUND: Hypervirulent Klebsiella pneumoniae (HVKp) infections have distinct clinical manifestations from classical K. pneumoniae infections. The hallmark of HVKp infections are liver abscess formation and metastatic infections. Due to the severe sequelae of these complications, method to identify patients at-risk of HVKp infections should be developed. RESULTS: A retrospective cohort study of 222 patients with K. pneumoniae bloodstream infections (BSIs) was performed. Patient demographics, clinical manifestations, and bacterial characteristics were investigated. Ten cases of liver abscesses were identified. Characteristics such as community-onset BSIs, hypermucoviscosity phenotype, and capsular serotype K1 were identified as risk factors for HVKp infections. A scoring system was developed based on the risk factors. The area under the receiver operating characteristic curve for the scoring system was 0.90. A score of ≥ 2 points provided sensitivity and specificity of 0.70 and 0.94, respectively. CONCLUSIONS: Simple scoring system was developed for the diagnosis of HVKp infections. The system allows early identification of patients with K. pneumoniae BSIs in whom hypervirulent infections should be evaluated. Prospective evaluation is expected.

Association of PIK3CA and MDM2 SNP309 with Cervical Squamous Cell Carcinoma in a Philippine Population.

Background: PIK3CA and MDM2 SNP309 have been studied to be associated with cervical cancer. PIK3CA mutation is associated with poor treatment response and low survival rate while MDM2 is associated with tumorigenesis and poor prognosis in cervical cancer. Thus, we determined the prevalence of PIK3CA and MDM2 mutations in Filipino cervical cancer patients. Methods: Twenty-eight formalin-fixed paraffin-embedded cervical squamous cell carcinoma and 16 non-malignant cervix tissue biopsies of Filipino patients were subjected to PIK3CA gene and MDM2 SNP309 (rs2279744) analysis. Results: PIK3CA gene was found mutated in three (10.71 %) out of 28 cervical cancer patients included in this study. Among the HPV-negative cervical cancer patients, two (28.57 %) were positive for PIK3CA mutation and only one (4.76 %) tested positive among the HPV-positive cervical cancer patients. MDM2 SNP309 analysis revealed that T allele (71.43%) was more common in cervical cancer patients compared to the control group. TG genotype (p = 0.03; OR = 0.18, 95% CI 0.04-0.76) was associated with lower rates of cervical cancer when TT genotype was used as a reference point. Conclusion: PIK3CA gene mutation was present among Filipino cervical cancer patients and not in control patients. MDM2 SNP309 analysis revealed that TG genotype has lower association to cervical cancer when compared with the TT and GG genotypes.

Type II restriction modification system in Ureaplasma parvum OMC-P162 strain.

Ureaplasma parvum serovar 3 strain, OMC-P162, was isolated from the human placenta of a preterm delivery at 26 weeks' gestation. In this study, we sequenced the complete genome of OMC-P162 and compared it with other serovar 3 strains isolated from patients with different clinical conditions. Ten unique genes in OMC-P162, five of which encoded for hypothetical proteins, were identified. Of these, genes UPV_229 and UPV_230 formed an operon whose open reading frames were predicted to code for a DNA methyltransferase and a hypothetical protein, respectively. DNA modification analysis of the OMC-P162 genome identified N4-methylcytosine (m4C) and N6-methyladenine (m6A), but not 5-methylocytosine (m5C). UPV230 recombinant protein displayed endonuclease activity and recognized the CATG sequence, resulting in a blunt cut between A and T. This restriction enzyme activity was identical to that of the cultivated OMC-P162 strain, suggesting that this restriction enzyme was naturally expressed in OMC-P162. We designated this enzyme as UpaP162. Treatment of pT7Blue plasmid with recombinant protein UPV229 completely blocked UpaP162 restriction enzyme activity. These results suggest that the UPV_229 and UPV_230 genes act as a type II restriction-modification system in Ureaplasma OMC-P162.

Biofilm-Forming Methicillin-Resistant Staphylococcus aureus Survive in Kupffer Cells and Exhibit High Virulence in Mice.

Although Staphylococcus aureus is part of the normal body flora, heavy usage of antibiotics has resulted in the emergence of methicillin-resistant strains (MRSA). MRSA can form biofilms and cause indwelling foreign body infections, bacteremia, soft tissue infections, endocarditis, and osteomyelitis. Using an in vitro assay, we screened 173 clinical blood isolates of MRSA and selected 20 high-biofilm formers (H-BF) and low-biofilm formers (L-BF). These were intravenously administered to mice and the general condition of mice, the distribution of bacteria, and biofilm in the liver, lung, spleen, and kidney were investigated. MRSA count was the highest in the liver, especially within Kupffer cells, which were positive for acid polysaccharides that are associated with intracellular biofilm. After 24 h, the general condition of the mice worsened significantly in the H-BF group. In the liver, bacterial deposition and aggregation and the biofilm-forming spot number were all significantly greater for H-BF group than for L-BF. CFU analysis revealed that bacteria in the H-BF group survived for long periods in the liver. These results indicate that the biofilm-forming ability of MRSA is a crucial factor for intracellular persistence, which could lead to chronic infections.

Hydrogen peroxide causes Vibrio vulnificus bacteriolysis accelerated by sulfonyl fluoride compounds.

Induction of bacteriolysis of Vibrio vulnificus cells by 10 mM hydrogen peroxide (H(2)O(2)) was analyzed. All Vibrio species examined, except for Vibrio hollisae, were lysed by 10 mM H(2)O(2). Bacteriophage induction was not the cause of H(2)O(2)-induced bacteriolysis. Autolysis is also known to cause bacteriolysis. VvpS protein is a serine protease of V. vulnificus essential for autolysis. vvpS mutant underwent H(2)O(2)-induced bacteriolysis in the same manner as the wild type. Protease inhibitors including serine protease inhibitors did not inhibit H(2)O(2)-induced bacteriolysis, which means that bacteriolysis is not due to autolysis. Unexpectedly, H(2)O(2)-induced bacteriolysis was accelerated by adding 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF) and phenylmethylsulfonyl fluoride which are serine protease inhibitors. The hydroxyl radical was generated by H(2)O(2)-AEBSF interaction. It was considered that H(2)O(2)-induced bacteriolysis was caused by the hydroxyl radical which was generated by Fenton reaction, and possibly mediated by AEBSF. Deferoxamine, an agent chelating ferric ion and Fenton reaction inhibitor, suppressed both H(2)O(2)-induced bacteriolysis and its acceleration by AEBSF. This suggests that both phenomena were Fenton reaction dependent, and hydroxyl radical generated by Fenton reaction caused bacteriolysis of V. vulnificus though the reason for high susceptibility of Vibrio species to hydroxyl radical is not known.

Influence of the bacterial phenotypes on the clinical manifestations in Klebsiella pneumoniae bacteremia patients: A retrospective cohort study.

Ninety-four episodes of Klebsiella pneumoniae bloodstream infection were identified at a university hospital in Japan. After excluding extended-spectrum beta lactamase-producing strains, 83 blood isolates from these patients were assayed in terms of their bacterial phenotypes such as the mucoid and hypermucoviscosity phenotypes. Bacterial phenotypes were correlated with the patients' clinical manifestations. The hypermucoviscosity phenotype was significantly associated with septic shock at the onset of infections (odds ratio, 15.92; 95% confidence interval, 1.27-468.12), but was not associated with liver abscess formation. Mortality was determined by the presence of septic shock. RmpA gene was associated with the induction of the hypermucoviscosity phenotype. These results reveal unique roles of bacterial phenotypes on the patient's clinical condition in K. pneumoniae bacteremia.