Clostridium species are gram-positive, spore-forming, anaerobic rods normally found in the soil and gastrointestinal tract of humans and animals. Spontaneous sepsis due to C. perfringens is not caused by injury, which sets it apart from the classical gas gangrene that typically follows trauma. Spontaneous C. perfringens sepsis often develops as a rapidly progressive intravascular hemolysis and metabolic acidosis, with high mortality rates of over 70% with standard intensive care. In such cases, alpha toxin secreted by C. perfringens is considered the main toxin responsible for intravascular hemolysis, disseminated intravascular coagulopathy, and multiple organ failure. Theta-toxin causes a cytokine cascade, which results in peripheral vasodilation similar to that seen in septic shock. For C. perfringens infections, antibiotics, such as high-dose penicillin, and surgical drainage as early as possible are the principal treatments of choice. However, considering the current mortality rate of sepsis, outcomes have not improved with the current standard treatment for C. perfringens infections. Monoclonal antibody against theta toxin in combination with gas gangrene antitoxin presents a promising therapeutic option.
Middle East respiratory syndrome (MERS) coronavirus (MERS-CoV) is usually diagnosed through highly sensitive and specific genetic tests such as real-time reverse transcription polymerase chain reaction (RT-PCR). Currently, two real-time RT-PCR assays targeting the upE and ORF1a regions of the MERS-CoV genome are widely used, and these are the standard assays recommended by the World Health Organization (WHO). The MERS outbreaks to date suggest that rapid diagnosis and subsequent isolation of infected patients, particularly superspreaders, are critical for containment. However, conventional real-time RT-PCR assays require large laboratory instruments, and amplification takes approximately 2 h. These disadvantages limit rapid diagnosis. Here, an ultra-rapid real-time RT-PCR test was established comprising a multiplex assay for upE and ORF1a running on a mobile PCR1100 device. As few as five copies of the MERS-CoV RNA can be detected within 20 min using the standard WHO assays in the mobile PCR device, with the sensitivity and specificity being similar to those of a conventional real-time PCR instrument such as the LightCyler, thereby enabling timely intervention to control MERS-CoV infection.
Intestinal protozoan parasites are common causes of infectious diarrhea in children receiving anticancer therapy or undergoing transplantation. Additionally, immunosuppression therapy in such patients may exacerbate the symptoms related to these parasitic infections. The aim of this study was to evaluate the prevalence and diagnostic importance of parasitic protozoan infections in children treated for malignancies or undergoing transplantation, and to highlight the control of intestinal parasitic infections for immunosuppressed patients at a hospital in İzmir, Turkey. In total, 82 stool samples from 62 patients were analyzed by microscopic examination and polymerase chain reaction (PCR) for the presence of coccidian parasites. Our results showed that Cryptosporidium, Cyclospora, and Cystoisospora were present in 22.5% (14/62), 9.6% (6/62), and 3.2% (2/62) of the cases using either method, respectively. The prevalence of these coccidian parasites identified with both methods was 35.4% (20/62). Other intestinal parasites (Blastocystis, Giardia, and Entamoebacoli) were detected in 10 patients. PCR analysis showed the presence of all coccidian parasites in the same stool sample for one patient. Finally, both PCR and microscopic examination of the stools revealed that there is a higher prevalence of Cryptosporidium, Cyclospora, and Cystoisospora in immunocompromised children. These examinations allowed an early start of appropriate antibiotic treatments and led to an increased percentage of correctly treated patients.
This study aimed to investigate antimicrobial resistance profile, multidrug resistance (MDR), and molecular characteristics of pathogenic Staphylococcus aureus isolates from hospitalized Vietnamese adults. Two hundred and twenty-three pathogenic S. aureus isolates were obtained from the hospitals located in 3 regions of Vietnam. The minimum inhibitory concentrations were determined to detect the antibiotic susceptibility of the isolates. The molecular characteristics of S. aureus isolates were investigated through antibiotic-resistant genes analysis, staphylococcal cassette chromosome mec typing, pulsed-field gel electrophoresis, and multilocus sequence typing. Substantial differences among the 3 regions were found in the prevalence rates of methicillin-resistant S. aureus (north: 48.6%, central: 58.7%, south: 78.9%) and MDR (north: 65.8%, central: 79.7%, and south: 84.2%). The prevalence rates of the genes tetK/M, aacA/aphD, ermA/B/C, and mecA increased substantially from north to south. ST188-SCCmecIV and ST239-SCCmecII isolates were most commonly found in the 2 largest clusters. ST188 predominance was observed in the largest cluster in methicillin-resistant and methicillin-sensitive S. aureus isolates, including SCCmecIII and SCCmecIVa, in fatal cases. Our results revealed a high occurrence of MDR and possible north−south trend in antibiotic resistance profile, MDR patterns, and frequency of antibiotic-conferring genes among S. aureus isolates. ST188 predominance raises concerns about the global importance of host-adapted ST188 in East Asian populations.
Orthohantaviruses infect humans via inhalation of the viral particles in the excreta of infected rodents or direct contact with infected rodents. The infections caused by Puumala orthohantavirus (PUUV) and Dobrava-Belgrade orthohantavirus (DOBV) have been reported in Turkey. Serum samples of 346 healthy volunteers who are in the high-risk group of Orthohantavirus infections among the residents of Çal, Baklan, Çivril, and Bekilli counties, located in the northeast part of Denizli province, were used in this study. The samples were screened and confirmed using commercial ELISA and immunoblot tests, which detect IgG antibodies against DOBV, PUUV, and Hantaan orthohantavirus. IgG antibodies against PUUV were detected in the samples of 2 volunteers (2/346, 0.6%). One was a veterinarian and the other a farmer and they live in the Baklan and Çal counties, respectively. Both of them have a high probability of exposure to the virus, based on their occupation and living conditions. However, no symptoms were found in the clinical findings of both cases. This study is the first publication of reported PUUV seropositivities from the southwestern part of Turkey.
Daptomycin is active against Staphylococcus aureus including methicillin-resistant S. aureus (MRSA), demonstrating efficacy in the treatment of infections in diabetic patients. However, daptomycin degrades in 5% glucose solution, and data on the efficacy of daptomycin in hyperglycemic patients are limited. Therefore, we investigated the effect of high levels of blood glucose on the efficacy and concentration of daptomycin. The efficacy of simulated human exposure to daptomycin against S. aureus was compared in a neutropenic murine thigh model, with and without hyperglycemia. A clinically isolated MRSA strain and S. aureus ATCC25923 standard strain were used. Daptomycin concentrations, in the serum and at the infected site, were preliminarily analyzed using the high-performance liquid chromatography assay. Even in hyperglycemic mice, the mean concentration of daptomycin in hyperglycemic mice was equivalent to that in untreated mice within the physiological blood glucose levels. Additionally, the efficacy of daptomycin against MRSA was equal to that observed in the untreated and hyperglycemic mice. Based on similar studies using S. aureus ATCC25923, the efficacy in hyperglycemic mice was equal to or greater than that observed in untreated mice. In conclusion, daptomycin is an alternative therapeutic option in diabetic mice with serious staphylococcal infections, regardless of blood glucose control in this animal model.
The aim of this study was to clarify the risk factors for chlamydial infection and determine whether infection during pregnancy is associated with preterm birth in Japanese women. The subjects were women who underwent Chlamydia trachomatis polymerase chain reaction testing during a singleton pregnancy and delivered after the 22nd week of gestation at a tertiary care center between January 1, 2000 and December 31, 2016. We compared Chlamydia-positive (n = 259) and Chlamydianegative (n = 1,974) groups and evaluated the pregnancy outcomes. The Chlamydia-positive group had a higher rate of public assistance coverage, smoking during pregnancy, nulliparity, lack of a partner, presence of other sexually transmitted infections, high-risk social status, and younger age (P < 0.01). The incidence of preterm births was not different between the groups, with an odds ratio of 0.95 (95% confidence interval: 0.62–1.46). The incidences of low birth weight deliveries, premature rupture of membranes, and preterm premature rupture of membranes prior to the 37th week were also comparable between the groups. Chlamydial infection during pregnancy had no effect on preterm birth, even after adjustment for confounding factors.
As one of the main antimicrobial peptides, human β-defensin 2 (HBD2) plays multiple roles in the lower genital tract. Based on the Nugent score as a diagnostic criterion for bacterial vaginosis, we sought to clarify the correlations among the Nugent score and interleukin-6 (IL-6) and HBD2 levels in vaginal secretions in association with various types of infection. Ninety-eight women were recruited for this study. Levels of HBD2 and IL-6 in vaginal wash were measured by enzyme-linked immunosorbent assays. According to the Nugent method, the number of Lactobacillus morphotypes per field of view was well correlated with the HBD2 level. The amount of HBD2 was also well correlated with the presence of Candida spp. (P < 0.01). In vitro experiments revealed that the expression of HBD2 from the human vaginal epithelial cell line, VK2/E6E7, was induced by the addition of heat-killed C. albicans (HKCA). The addition of HKCA induced expression of Dectin-1 mRNA. A luciferase assay for nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) responsive elements showed that HKCA activated NF-κB signaling. These results suggested that C. albicans induced the activation of Dectin-1 and (NF-κB) signaling, resulting in HBD2 expression. In conclusion, the expression of HBD2 positively correlated with the presence of Lactobacillus and Candida spp.
Adult T-cell leukemia (ATL) is induced by chronic latent infection with human T-cell leukemia virus type 1 (HTLV-1). HTLV-1 Tax is an oncogenic factor that can be targeted by host T-cell responses. However, the expression of Tax in vivo is little in ATL cells and the impact of Tax-specific T-cell responses on ATL progression remains unclear. In the present study, we examined Tax-specific T-cell responses in C57BL/6 mice after syngeneic transplantation with tax-transgenic mouse-derived ATL (mATL) cells. We first confirmed that cellular tax cDNAs are mostly maintained and detectable in the spleen three weeks after mATL cell transplantation. However, mATL cell transplantation did not induce significant Tax-specific T-cell responses. Mice immunized with DNA and adenovirus vectors expressing Tax exhibited Tax-specific CD4+ T-cell responses but showed no enhancement of the responses or reduction in cellular tax cDNA levels after mATL cell transplantation. This study provides an animal model for analyzing the interaction between ATL cells and host immune responses as well as indicates the limited impact of Tax-specific T-cell responses on the proliferation of ATL cells.
Varicella-zoster virus (VZV) is a ubiquitous human herpesvirus that causes chickenpox and zoster. Considering that VZV is a relatively and genetically stable virus, its global surveillance clades provide essential information for VZV evolution, immigration, and importation of different viral strains and recombination events. Eighty-eight VZV isolates from China (Shanghai and Urumqi) were genotyped using a scattered single-nucleotide polymorphism method in this prospective study. Our results were based on sequencing the open reading frames 1, 6, 12, 16, 17, 21, 22, 35, 37, 38, 50, 54, 55, 56, 60, and 66. We found that the majority of these 88 strains (81.8%) belonged to Clade 2 with significantly high homogeneity from Shanghai. However, in the Urumqi area, some strains were grouped to Clade 5, and some could not be attributed to any of the established VZV clades, although the majority of Urumqi strains belonged to Clade 2. Our results illustrated that due to geographical location, VZV could undergo genetic recombination, suggesting that VZV diversity is more complicated in certain areas and geographical separation contributes to VZV complexity.
To clarify the pertussis immune status of the Japanese population, we investigated levels of serum pertussis toxin (PT)-specific immunoglobulin G (IgG) antibody in infants and mothers between April 2016 and March 2018. A total of 206 infants (n = 22, < 32 weeks of gestational age [wGA]; n = 70, 32–36 wGA; n = 114, ≥ 37 wGA) and 170 mothers were enrolled. The maternal seroprevalence and antibody geometric mean titer (GMT) were 52.4% and 10.7 EU/mL, respectively. The antibody GMT, seroprevalence, and mean ratio of infant to maternal antibody titers of infants at < 32 wGA were 3.2 EU/mL, 13.6%, and 42.5%, respectively, and were significantly lower than those of infants at 32–36 wGA (9.7 EU/mL, 54.3%, and 110.2%) and infants at ≥ 37 wGA (12.1 EU/mL, 57.9%, and 112.6%). Of the 21 infants who underwent a second examination, five were positive in the first examination. Of those five, the GMT for PT had decreased by an average of 52.6% at 4.3- week intervals. In the second examination, two infants were seropositive. Approximately half of the mothers and infants were negative for anti-PT antibody. Thus, new vaccination strategies, such as the vaccination of pregnant women, are needed to prevent pertussis infection in early infancy.
The monoclonal antibody 1C10 targets the V3 loop of HIV-1 and neutralizes a broad range of clade B viruses. However, the mode of interaction between 1C10 and the V3 loop remains unclear because crystallization of 1C10 and the V3 peptide was unsuccessful due to the flexible regions present in both 1C10 and the V3 peptide. In this study, we predicted the 1C10 amino acid residues that make contact with the V3 loop using a deep learning (DL)-based method. Inputs from ROSIE for docking simulation and FastContact, Naccess, and PDBtools, to approximate interactions were processed by Chainer for DL, and outputs were obtained as probabilities of contact residues. Using this DL algorithm, D95, D97, P100a, and D100b of CDRH3; D53, and D56 of CDRH2; and D61 of FR3 were highly ranked as contact residues of 1C10. Substitution of these residues with alanine significantly decreased the affinity of 1C10 to the V3 peptide. Moreover, the higher the rank of the residue, the more the binding activity diminished. This study demonstrates that the prediction of contact residues using a DL-based approach is a precise and useful tool for the analysis of antibody-antigen interactions.
This study investigated quinolone nonsusceptible Streptococcus canis with point mutations in quinolone resistance-determining regions (QRDRs). After selecting targets from 185 isolates, we tested antimicrobial susceptibility using levofloxacin, ciprofloxacin, norfloxacin, and moxifloxacin. We also determined the amino acid sequences of QRDRs in gyrA/gyrB/parC/parE genes and their point mutations. Finally, we performed S. canis-derived M-like protein (SCM) allele typing, multilocus sequence typing, and antimicrobial resistance genotyping. Correlations between nonsusceptible strains and their related factors were examined. We found 13 (7.0%) nonsusceptible isolates consisting of two classes, high-level minimum inhibitory concentrations (MICs) (n = 7, 3.8%) and low-level MICs (n = 6, 3.2%). Mutations Ser81Phe/Ser81Tyr/Glu85Lys in gyrA, Ser67Phe/Ser67Tyr/Asp71Tyr in parC, Asp438Asn in parE, and Gly408Asp in gyrB were observed in these nonsusceptible strains. Common mutations included Ser81 and Ser67/Asp71; additionally, we found one strain each with Glu85, Asp438, and Gly408 mutations. There was a significant correlation between nonsusceptible isolates and the presence of SCM allele type 2, sequence type 46, tetracyclineresistance genes, and macrolide/lincosamide-resistance genes. These results could be used in future, by veterinarians while treating companion animals with clinical symptoms of streptococcal infections.
Ravuconazole (RVCZ) is a new human anti-fungal azole drug available in Japan since 2018 and is a broad-spectrum agent that exhibits excellent activity against dermatophytes. In the present study, the in vitro RVCZ susceptibility of clinical isolates of anthropophilic dermatophytes, including Trichophyton interdigitale strains with either low susceptibility to itraconazole (ITCZ) or resistance to terbinafine (TEBR), was investigated using the Clinical & Laboratory Standards Institute M38-A2 test. The MICs of RCVZ for 20 clinical isolates of T. interdigitale were < 0.03125–0.125 mg/L; for 4 clinical isolates of T. rubrum, < 0.03125–0.0625 mg/L; and for 20 clinical isolates of T. tonsurans, < 0.03125 mg/L. Similarly, the MICs of RCVZ for the T. interdigitale strains with either low susceptibility to ITCZ or resistance to TEBR were also < 0.03125 mg/L. To our knowledge, this is first study to investigate the in vitro RVCZ susceptibility of T. interdigitale strains with either low susceptibility to ITCZ or resistance to TEBR. Our results indicated that RVCZ was the most effective drug against these strains.
Considering the possibility that Escherichia coli carried by companion dogs could infect owners and human society, we investigated their pathogenicity and drug resistance. E. coli was isolated from stool samples of companion dogs (n = 90) to examine the O-serogroup, virulence genes, and drug susceptibility. The age of dogs ranged from 4 months to 16 years, and they were mainly treated with cefalexin, enrofloxacin, or amoxicillin. A total of 69 samples were positive for E. coli (76% of examined dogs), and the most common O-serogroup was O18 (n = 13). Nine diarrheagenic E. coli, including enteropathogenic E. coli (n = 3), enteroaggregative E. coli (n = 1), and astA-carrying E. coli (n = 5), were isolated. In addition, we isolated 28 E. coli strains resistant to at least one of six antimicrobials, including cephalothin (CET), ceftazidime (CAZ), cefotaxime (CTX), chloramphenicol (CP), fosfomycin (FOM), and norfloxacin (NLFX). The resistance pattern was as follows: CET, n = 16; NLFX, n = 3; CET/CP (resistance to both CET and CP), n = 1; CET/NLFX, n = 1; CET/CAZ/CTX, n = 3; CET/CTX/NLFX, n = 2; CET/CP/NLFX, n = 1; and CET/CAZ/CTX/NLFX, n = 1. Moreover, ten E. coli isolates were found to produce extended-spectrum β-lactamase (ESBL), including AmpC (n = 4; OUT, O18, O74, and O166), CTX-M-1 (n = 1; O25), CTX-M-9 (n = 4; OUT, O18, O18, and O125), and AmpC/CTX-M-9 (n = 1; OUT) groups. The AmpC-producing E. coli strains included enteropathogenic and astA-carrying E. coli. Our results showed that the human-infectious diarrheagenic E. coli was isolated from some dogs, and some strains exhibited ESBL. Therefore, future studies are needed to investigate the possibility of transmission of these E. coli strains to humans.