Molecular and descriptive epidemiology of intestinal protozoan parasites of children and their pets in Cauca, Colombia: a cross-sectional study

BACKGROUND

Parasitic infections, particularly those caused by protozoa, represent a considerable public health problem in developing countries. Blastocystis, Giardia duodenalis, Cryptosporidium spp. and the Entamoeba complex (Entamoeba histolytica, Entamoeba dispar and Entamoeba moshkovskii) are the most common etiological causes of intestinal parasitic infections.

METHODS

We carried out a descriptive cross-sectional study in school-age children attending a daycare institution in commune eight of Popayán, Cauca (Southwest Colombia). A total of 266 fecal samples were collected (258 from children and eight from pets). Blastocystis, G. duodenalis, Cryptosporidium spp. and the Entamoeba complex were identified by microscopy, quantitative real-time PCR (qPCR) and conventional PCR. The concordance of qPCR and microscopy was assessed using the Kappa index. Molecular characterization was conducted to identify Blastocystis subtypes (18S), G. duodenalis assemblages (tpi and gdh) and Cryptosporidium species/subtypes (18S and GP60). Potential associations between intestinal parasitism and sociodemographic factors were examined using bivariate analyses.

RESULTS

A total of 258 fecal samples from children were analyzed by microscopy and 255 samples were analyzed by qPCR. The prevalence of Blastocystis was between 25.19% (microscopy) and 39.22% (qPCR), that of G. duodenalis was between 8.14% (microscopy) and 10.59% (qPCR), that of Cryptosporidium spp. was estimated at 9.8% (qPCR), and that of the Entamoeba complex was between 0.39% (conventional PCR) and 0.78% (microscopy). The concordance between microscopy and qPCR was very low. Blastocystis ST1 (alleles 4, 8, and 80), ST2 (alleles 11, 12, and 15), ST3 (alleles 31, 34, 36, 38,57, and 151), and ST4 (alleles 42 and 91), G. duodenalis assemblages AII, BIII, BIV and D, C. parvum subtype IIa and C. hominis subtype IbA9G3R2 were identified. The only identified member of the Entamoeba complex corresponded to E. histolytica. No statistically significant association was identified between parasitic infection and any sociodemographic variable.

CONCLUSION

This study revealed the usefulness of molecular methods to depict the transmission dynamics of parasitic protozoa in southwest Colombia. The presence of some of these protozoa in domestic animals may be involved in their transmission.

Phagocytosis of Gut Bacteria by Entamoeba histolytica

The protist parasite Entamoeba histolytica causes amoebiasis, a major public health problem in developing countries. Only a small fraction of patients infected with the parasite display invasive disease involving colon or extra intestinal tissues such as liver. E. histolytica exists as two distinct forms, cysts, the infective form, and trophozoites, that are responsible for disease pathology. The latter multiply in the large intestine occasionally causing disease. The large intestine in humans is populated by a number of different bacterial communities and amoebic cells grow in their midst using some as food material. Several studies have shown relationship between bacteria and E. histolytica growth and virulence. However, an understanding of this relationship in human gut environment is not clear. We have investigated the possibility that there may be specific interaction of amoeba with different bacteria present in the gut environment by using a metagenomic pipe line. This was done by incubating bacteria isolated from human fecal material with E. histolytica and then identifying the bacterial population isolated from amoebic cells using a rRNA based metagenomic approach. Our results show that the parasite prefers a few bacterial species. One of these species is Lactobacillus ruminus which has never shown to be associated with E. histolytica.

Hemizygosity Enables a Mutational Transition Governing Fungal Virulence and Commensalism

Candida albicans is a commensal fungus of human gastrointestinal and reproductive tracts, but also causes life-threatening systemic infections. The balance between colonization and pathogenesis is associated with phenotypic plasticity, with alternative cell states producing different outcomes in a mammalian host. Here, we reveal that gene dosage of a master transcription factor regulates cell differentiation in diploid C. albicans cells, as EFG1 hemizygous cells undergo a phenotypic transition inaccessible to "wild-type" cells with two functional EFG1 alleles. Notably, clinical isolates are often EFG1 hemizygous and thus licensed to undergo this transition. Phenotypic change corresponds to high-frequency loss of the functional EFG1 allele via de novo mutation or gene conversion events. This phenomenon also occurs during passaging in the gastrointestinal tract with the resulting cell type being hypercompetitive for commensal and systemic infections. A "two-hit" genetic model therefore underlies a key phenotypic transition in C. albicans that enables adaptation to host niches.

Comparison of Two PCR Assays for Trichomonas vaginalis

PCR is known to be the most sensitive method for diagnosing Trichomonas vaginalis infections. This study aimed to compare the sensitivity of a PCR assay for trichomoniasis (HY-PCR) developed in Hanyang University with the use of a Seeplex Ace Detection Kit®, using urine collected from four Korean men with prostatic disease. Overall, HY-PCR was more sensitive than the Seeplex Kit. The use of Chelex 100 is recommended for DNA isolation in order to increase the sensitivity of the PCR test.

Genome and pan-genome analysis to classify emerging bacteria

Background

In the recent years, genomic and pan-genomic studies have become increasingly important. Culturomics allows to study human microbiota through the use of different culture conditions, coupled with a method of rapid identification by MALDI-TOF, or 16S rRNA. Bacterial taxonomy is undergoing many changes as a consequence. With the help of pan-genomic analyses, species can be redefined, and new species definitions generated.

Results

Genomics, coupled with culturomics, has led to the discovery of many novel bacterial species or genera, including Akkermansia muciniphila and Microvirga massiliensis. Using the genome to define species has been applied within the genus Klebsiella. A discontinuity or an abrupt break in the core/pan-genome ratio can uncover novel species.

Conclusions

Applying genomic and pan-genomic analyses to the reclassification of other bacterial species or genera will be important in the future of medical microbiology. The pan-genome is one of many new innovative tools in bacterial taxonomy.

Reviewers

This article was reviewed by William Martin, Eric Bapteste and James Mcinerney.

Open peer review

Reviewed by William Martin, Eric Bapteste and James Mcinerney.

Potential for Molecular Testing for Group A Streptococcus to Improve Diagnosis and Management in a High-Risk Population: A Prospective Study

Background

In high-burden settings, guidelines recommend antibiotic treatment for all suspected group A Streptococcus (GAS) infections to prevent rheumatic fever and poststreptococcal glomerulonephritis. Highly sensitive rapid GAS tests could reduce unnecessary antibiotic use in these settings.

Methods

This was a prospective study of the Xpert Xpress Strep A (Cepheid) molecular test compared with culture of throat swab samples collected at a referral hospital in northern Australia. Demographic and clinical data and results of streptococcal serology and culture were collected.

Results

Of 164 throat swab samples, 145 (88%) were eligible for inclusion; 49 (34%) were molecular test positive and 24 (17%) were culture positive for GAS. The sensitivity, specificity, and positive and negative predictive values for the molecular test versus culture were 100.0%, 79.3%, 48.8%, and 100.0%, respectively. Among 25 samples testing positive with the molecular test and negative with culture, group C or G streptococci were cultured in 2, and a plausible clinical explanation, such as pharyngotonsillitis, or rheumatic fever with positive results of streptococcal serology, was apparent in 19 instances. In 25 patients with rheumatic fever or poststreptococcal glomerulonephritis diagnoses, molecular testing nearly trebled the detection of GAS in throat swab samples, from 3 (12%) detected with culture to 8 (32%) detected with molecular testing. Reasons for “false-positive” molecular test results could include the presence of GAS below the threshold of culture detection or persistence of nonviable organisms after infection.

Conclusion

Implementation of molecular testing could improve antibiotic use in this high-burden setting. The incremental yield in poststreptococcal syndromes, by which time cultures are negative, has high potential in the diagnostic workup of autoimmune poststreptococcal syndromes and warrants further investigation.

Predictors and outcomes of disseminated tuberculosis in an intermediate burden setting

SETTING

University-affiliated hospital located in Porto, North Portugal, an area with a low to intermediate incidence of tuberculosis (TB).

OBJECTIVE

To identify predictors and outcomes of disseminated TB (dTB).

DESIGN

A cohort of patients diagnosed with TB between 2007 and 2013 was retrospectively analysed. Patients with dTB criteria were characterized and compared to single organ TB cases. Factors independently associated with dTB were determined by multivariate logistic regression analysis.

RESULTS

A total of 744 patients were analysed, including 145 with dTB. Independent risk factors for dTB were pharmacological immunosuppression (OR 5.6, 95% CI 2.8-11.3), HIV infection (OR 5.1, 95% CI 3.1-8.3), chronic liver failure or cirrhosis (OR 2.3, 95% CI 1.4-4.1) and duration of symptoms (OR 2.3, 95% CI 1.4-3.8). Compared to single organ TB, the clinical presentation of dTB patients differed by the absence of haemoptysis (OR 3.2, 95% CI 1.3-8.4) and of dyspnoea (OR 1.9, 95% CI 1.2-3.1), presence of weight loss (OR 1.8, 95% CI 1.1-2.9), night sweats (OR 1.7, 95% CI 1.1-2.7) and bilateral lung involvement (OR 4.4, 95% CI 2.8-7.1). Mortality and time until culture conversion were higher for dTB patients, although not reaching statistical significance.

CONCLUSION

Immunosuppressive conditions and chronic liver failure or cirrhosis were associated with increased risk of dTB. The haematogenous spread may be dependent on longer symptomatic disease and usually progresses with bilateral lung involvement.

Evaluation of 4-Amino 2-Anilinoquinazolines against Plasmodium and Other Apicomplexan Parasites In Vitro and in a P. falciparum Humanized NOD-scid IL2Rγnull Mouse Model of Malaria

A series of 4-amino 2-anilinoquinazolines optimized for activity against the most lethal malaria parasite of humans, Plasmodium falciparum, was evaluated for activity against other human Plasmodium parasites and related apicomplexans that infect humans and animals. Four of the most promising compounds from the 4-amino 2-anilinoquinazoline series were equally as effective against the asexual blood stages of the zoonotic P. knowlesi, suggesting that they could also be effective against the closely related P. vivax, another important human pathogen. The 2-anilinoquinazoline compounds were also potent against an array of P. falciparum parasites resistant to clinically available antimalarial compounds, although slightly less so than against the drug-sensitive 3D7 parasite line. The apicomplexan parasites Toxoplasma gondii, Babesia bovis, and Cryptosporidium parvum were less sensitive to the 2-anilinoquinazoline series with a 50% effective concentration generally in the low micromolar range, suggesting that the yet to be discovered target of these compounds is absent or highly divergent in non-Plasmodium parasites. The 2-anilinoquinazoline compounds act as rapidly as chloroquine in vitro and when tested in rodents displayed a half-life that contributed to the compound's capacity to clear P. falciparum blood stages in a humanized mouse model. At a dose of 50 mg/kg of body weight, adverse effects to the humanized mice were noted, and evaluation against a panel of experimental high-risk off targets indicated some potential off-target activity. Further optimization of the 2-anilinoquinazoline antimalarial class will concentrate on improving in vivo efficacy and addressing adverse risk.

Evolution of Daptomycin Resistance in Coagulase-Negative Staphylococci Involves Mutations of the Essential Two-Component Regulator WalKR

Coagulase-negative staphylococci (CoNS) represent one of the major causes of health care- and medical device-associated infections. Emerging antimicrobial resistance has complicated the treatment of systemic infections caused by CoNS. Here, we describe the prevalence of antimicrobial resistance in clinical CoNS strains from a tertiary care hospital over a 4-year period, and we observed a significant increase in resistance to daptomycin. Notably, Staphylococcus capitis accounted for the majority of these daptomycin-resistant (DAP-R) CoNS. To further investigate the mechanisms of daptomycin resistance in CoNS, daptomycin-susceptible clinical strains of S. capitis and Staphylococcus epidermidis underwent in vitro daptomycin exposure to generate DAP-R CoNS mutants. Unlike that seen with Staphylococcus aureus, alteration of cell surface charge was not observed in the DAP-R CoNS strains, but biofilm formation was compromised. Whole-genome sequencing analysis of the DAP-R CoNS strains identified single nucleotide polymorphisms (SNPs) in walKR, the essential two-component regulatory system controlling cell wall biogenesis. PCR and sequencing of walK and walR from 17 DAP-R CoNS clinical isolates identified seven nonsynonymous mutations. The results were confirmed by the recreation of the walK SNP in S. epidermidis, which resulted in reduced susceptibility to daptomycin and vancomycin. This study highlights the significance of CoNS in evolving daptomycin resistance and showed that walKR is shared among the staphylococcal species and is involved in antibiotic resistance development. Notably, we did not observe mutations in genes responsible for phospholipid biosynthesis or an altered cell surface charge, suggesting that reduced daptomycin susceptibility in CoNS may emerge in a fashion distinct from that in S. aureus.

Meningoencephalitis caused by Lactobacillus plantarum - case report

Specific strains of Lactobacillus spp. are widely used as probiotic agents but it has been repeatedly reported that may have a pathogenic potential. We present the report on a case of meningoencephalitis caused by Lactobacillus plantarum in a 63-year-old man with newly diagnosed metastatic planoepitheliale lung cancer. The patient was hospitalised due to newly diagnosed cancer and during the course of hospitalisation developed symptoms of neuroinfection. On the basis of the symptoms and results of the conducted tests the patient was diagnosed with bacterial meningoencephalitis. In microbiological tests of the blood and cerebrospinal fluid L. plantarum was cultured. During the course of antibiotic therapy the patient's condition improved. Lactobacilli are now recognised as a causative agent of infection, most notably bacteraemia. To our knowledge, this is the fourth documented case of Lactobacillus-associated neuroinfection, and only the second in an adult. Lactobacilli cause mostly opportunistic infections in immunocompromised individuals.

Vacuolar Sequestration of Azoles, a Novel Strategy of Azole Antifungal Resistance Conserved across Pathogenic and Nonpathogenic Yeast

Target alteration and overproduction and drug efflux through overexpression of multidrug transporters localized in the plasma membrane represent the conventional mechanisms of azole antifungal resistance. Here, we identify a novel conserved mechanism of azole resistance not only in the budding yeast Saccharomyces cerevisiae but also in the pathogenic yeast Candida albicans We observed that the vacuolar-membrane-localized, multidrug resistance protein (MRP) subfamily, ATP-binding cassette (ABC) transporter of S. cerevisiae, Ybt1, could import azoles into vacuoles. Interestingly, the Ybt1 homologue in C. albicans, Mlt1p, could also fulfill this function. Evidence that the process is energy dependent comes from the finding that a Mlt1p mutant version made by converting a critical lysine residue in the Walker A motif of nucleotide-binding domain 1 (required for ATP hydrolysis) to alanine (K710A) was not able to transport azoles. Additionally, we have shown that, as for other eukaryotic MRP subfamily members, deletion of the conserved phenylalanine amino acid at position 765 (F765Δ) results in mislocalization of the Mlt1 protein; this mislocalized protein was devoid of the azole-resistant attribute. This finding suggests that the presence of this protein on vacuolar membranes is an important factor in azole resistance. Further, we report the importance of conserved residues, because conversion of two serines (positions 973 and 976, in the regulatory domain and in the casein kinase I [CKI] consensus sequence, respectively) to alanine severely affected the drug resistance. Hence, the present study reveals vacuolar sequestration of azoles by the ABC transporter Ybt1 and its homologue Mlt1 as an alternative strategy to circumvent drug toxicity among pathogenic and nonpathogenic yeasts.

Latent TB Infection (LTBI) - Mycobacterium tuberculosis pathogenesis and the dynamics of the granuloma battleground

Latent tuberculosis infection (LTBI) is established in over 90% of persons infected with Mycobacterium tuberculosis (Mtb), from whom new active TB cases will arise. Understanding the spatio-temporal dynamics of host immune responses in LTBI granulomas is essential to designing effective post-exposure therapies that inhibit progression to TB. Information arising from cancer studies and other modalities - where local chronic inflammation leads to immunopathology - can help provide insights into the biological pathways at play in LTBI granulomas. Translational studies using patient material as well as LTBI+ donor-derived tissue samples are instrumental in understanding the various components of granuloma dynamics, immunological landscapes therein and how this could help to identify therapeutic targets. Deep sequencing technologies may aid to decipher the genetic changes in lung granuloma and blood samples from LTBI+ individuals associated with progression to active TB disease. This may lead to advancement of development of targeted Host-Directed Therapies (HDTs) and their evaluation as adjunct TB therapies for improving treatment outcomes for LTBI and pulmonary TB.

The first isolation of Clostridium difficile RT078/ST11 from pigs in China

We investigated the molecular characteristics and antimicrobial susceptibility of Clostridium difficile isolated from animals in China. We obtained 538 rectal swabs from pigs, chickens and ducks in 5 provinces during 2015 and 2016. C. difficile isolates were characterized by detection of toxin genes, multilocus sequence typing and ribotyping. And antimicrobial susceptibility testing was performed using the agar dilution method. Out of 538 samples, 44 (8.2%) were C. difficile positive with high prevalence in pigs (n = 31). Among these, 39 (88.6%) were toxigenic including 14 (31.8%) that were A+B+CDT+ and 13 (29.5%) A+B+. The remaining 12 (27.3%) were A-B+. We identified 7 ST types and 6 PCR ribotypes. The most predominant type was ST11/RT078 with toxin profile A+B+CDT+ and all were isolated from piglets with diarrhea. ST109 isolates possessed two different toxigenic profiles (A-B-CDT- and A-B+CDT-) and although it was not the most prevalent sequence type, but it was widely distributed between chickens, ducks and pigs in the 5 provinces. All C. difficile isolates were fully susceptible to vancomycin, metronidazole, fidaxomicin, amoxicillin/clavulanate and meropenem but retained resistance to 4 or 5 of the remaining antibiotics, especially cefotaxime, tetracycline, ciprofloxacin, cefoxitin. The RT078/ST11 isolates were simultaneously resistant to cefotaxime, tetracycline, cefoxitin, ciprofloxacin and imipenem. This is the first report of the molecular epidemiology of C. difficile isolated from food animals in China. We identified the epidemic strain RT078/ST11 as the predominate isolate among the animals we screened in our study.

Understanding Real-Time Fluorescence Signals from Bacteria and Wound Tissues Observed with the MolecuLight i:XTM

The persistent presence of pathogenic bacteria is one of the main obstacles to wound healing. Detection of wound bacteria relies on sampling methods, which delay confirmation by several days. However, a novel handheld fluorescence imaging device has recently enabled real-time detection of bacteria in wounds based on their intrinsic fluorescence characteristics, which differ from those of background tissues. This device illuminates the wound with violet (405 nm) light, causing tissues and bacteria to produce endogenous, characteristic fluorescence signals that are filtered and displayed on the device screen in real-time. The resulting images allow for rapid assessment and documentation of the presence, location, and extent of fluorescent bacteria at moderate-to-heavy loads. This information has been shown to assist in wound assessment and guide patient-specific treatment plans. However, proper image interpretation is essential to assessing this information. To properly identify regions of bacterial fluorescence, users must understand: (1) Fluorescence signals from tissues (e.g., wound tissues, tendon, bone) and fluids (e.g., blood, pus); (2) fluorescence signals from bacteria (red or cyan); (3) the rationale for varying hues of both tissue and bacterial fluorescence; (4) image artifacts that can occur; and (5) some potentially confounding signals from non-biological materials (e.g., fluorescent cleansing solutions). Therefore, this tutorial provides clinicians with a rationale for identifying common wound fluorescence characteristics. Clinical examples are intended to help clinicians with image interpretation-with a focus on image artifacts and potential confounders of image interpretation-and suggestions of how to overcome such challenges when imaging wounds in clinical practice.

Prevention of transfusion-transmitted infections

Since the 1970s, introduction of serological assays targeting virus-specific antibodies and antigens has been effective in identifying blood donations infected with the classic transfusion-transmitted infectious agents (TTIs; hepatitis B virus [HBV], HIV, human T-cell lymphotropic virus types I and II, hepatitis C virus [HCV]). Subsequently, progressive implementation of nucleic acid-amplification technology (NAT) screening for HIV, HCV, and HBV has reduced the residual risk of infectious-window-period donations, such that per unit risks are <1 in 1 000 000 in the United States, other high-income countries, and in high-incidence regions performing NAT. NAT screening has emerged as the preferred option for detection of newer TTIs including West Nile virus, Zika virus (ZIKV), and Babesia microti Although there is continual need to monitor current risks due to established TTI, ongoing challenges in blood safety relate primarily to surveillance for emerging agents coupled with development of rapid response mechanisms when such agents are identified. Recent progress in development and implementation of pathogen-reduction technologies (PRTs) provide the opportunity for proactive rather than reactive response to blood-safety threats. Risk-based decision-making tools and cost-effectiveness models have proved useful to quantify infectious risks and place new interventions in context. However, as evidenced by the 2015 to 2017 ZIKV pandemic, a level of tolerable risk has yet to be defined in such a way that conflicting factors (eg, theoretical recipient risk, blood availability, cost, and commercial interests) can be reconciled. A unified approach to TTIs is needed, whereby novel tests and PRTs replace, rather than add to, existing interventions, thereby ameliorating cost and logistical burden to blood centers and hospitals.

Collinsella vaginalis sp. nov. strain Marseille-P2666T, a new member of the Collinsella genus isolated from the genital tract of a patient suffering from bacterial vaginosis

A strictly anaerobic, Gram-stain-positive, non motile and non-spore-forming rod-shaped bacterium, strain Marseille-P2666^T, was isolated using the culturomics approach from a vaginal sample of a French patient suffering from bacterial vaginosis. Cells were saccharolytic and were negative for catalase, oxidase, urease, nitrate reduction, indole production, hydrolysis of aesculin and gelatin. Strain Marseille-P2666^T exhibited 97.04 % 16S rRNA sequence similarity to Collinsella tanakaei type strain YIT 12063^T, the phylogenetically closest species with standing in nomenclature. The major fatty acids were C18:1ω9 (38 %), C16 : 0 (24 %) and C18 : 0 (19 %). The G+C content of the genome sequence of strain Marseille-P2666^T is 64.6 mol%. On the basis of its phenotypic, phylogenetic and genomic features, strain Marseille-P2666^T (=CSUR 2666^T=DSM103342^T) was classified as type strain of a novel species within the genus Collinsella for which the name Collinsella vaginalis sp. nov. is proposed.

Long actin-based cellular protrusions as novel evidence of the cytopathic effect induced in immune cells infected by the ectromelia virus

The aim of the study was to evaluate the influence of ectromelia virus (ECTV) infection on actin cytoskeleton rearrangement in immune cells, such as macrophages and dendritic cells (DCs). Using scanning electron and fluorescence microscopy analysis we observed the presence of long actin-based cellular extensions, formed by both types of immune cells at later stages of infection with ECTV. Such extensions contained straight tubulin filaments and numerous punctuate mitochondria. Moreover, these long cellular projections extended to a certain length and formed convex structures termed “cytoplasmic packets”. These structures contained numerous viral particles and presumably were sites of progeny virions’ release via budding. Further, discrete mitochondria and separated tubulin filaments that formed a scaffold for accumulated mitochondria were visible within cytoplasmic packets. ECTV-induced long actin-based protrusions resemble “cytoplasmic corridors” and probably participate in virus dissemination. Our data demonstrate the incredible capacity for adaptation of ECTV to its natural host immune cells, in which it can survive, replicate and induce effective mechanisms for viral spread and dissemination.

Diagnosis and Management of Group a Streptococcal Pharyngitis in the United States, 2011-2015

Background

Clinical guidelines for the diagnosis of group A streptococcal (GAS) pharyngitis recommend the use of a rapid antigen detection test (RADT) and/or bacterial culture. This study evaluated the overall diagnosis and treatment of acute pharyngitis in the United States, including predictors of test type and antibiotic prescription.

Methods

A retrospective analysis of pharyngitis events from 2011 through 2015 was conducted using the MarketScan commercial/Medicare databases. A pharyngitis event was defined as occurring within 2 weeks from the index visit. Patient and provider characteristics were examined across 5 testing categories: RADT, RADT plus culture, other tests, nucleic acid amplification testing (NAAT), and no test. Multivariate models were used to identify significant predictors of NAAT use and antibiotic prescription.

Results

A total of 18.8 million acute pharyngitis events were identified in 11.6 million patients. Roughly two-thirds of events (68.2%) occurred once, and roughly a third of patients (29.1%) required additional follow-up, but hospitalization was rare (0.3%). Across all events, 43% were diagnosed by RADT, while 20% were diagnosed by RADT plus culture. The proportion of events diagnosed by NAAT increased 3.5-fold from 2011 to 2015 (0.06% vs 0.27%). Antibiotic use was frequent (49.3%), less often in combination with RADT plus culture (31.2%) or NAAT alone (34.5%) but significantly more often with RADT alone (53.4%) or no test (57.1%). Pediatricians were significantly less likely than other providers to prescribe antibiotics in their patients, regardless of patient age (p < 0.0001).

Conclusions

Antibiotic use for sore throat remains common, with many clinicians not following current guidelines for diagnosis of GAS pharyngitis. Diagnosis of GAS pharyngitis using RADT plus culture or NAAT alone was associated with lower use of antibiotics. Diagnostic testing can help lower the incidence of inappropriate antibiotic use, and inclusion of NAAT in the clinical guidelines for GAS pharyngitis warrants consideration.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3835-4) contains supplementary material, which is available to authorized users.

Prevalence of plasmid-mediated AmpC in Enterobacteriaceae isolated from humans and from retail meat in Zagazig, Egypt

Background

The objective of this study was to determine the prevalence of plasmid-mediated AmpC (pAmpC) among Enterobacteriaceae isolated from humans and from retail meat in Egypt.

Methods

Enterobacteriaceae were isolated from patients with suspected bloodstream infection, human fecal samples, retail chicken meat samples and retail sheep meat samples. All group I Enterobacteriaceae were analyzed for presence of pAmpC genes by PCR. Antibiotic susceptibility testing was performed in all pAmpC positive isolates, followed by phenotypic and genotypic ESBL and carbapenemase testing on indication.

Results

The prevalence of pAmpC among group I Enterobacteriaceae isolated from 225 patients with bloodstream infection was 5.6% [95%CI 2.2–13.4]. Among 100 patients with community-onset gastroenteritis the prevalence in fecal samples was 4.8% [95%CI 2.1–10.7]. The prevalence among 112 chicken carcasses and 100 sheep meat samples was 2.4% [95%CI 0.7–8.4] and 1.1% [95%CI 0.2–5.7], respectively. In half of the AmpC positive isolates we detected an ESBL gene and 2 isolates harbored a carbapenemase gene. In five isolates there was resistance to at least three important alternative antibiotic drugs.

Conclusions

We consider the prevalence of pAmpC in Egypt, as found in our study, moderately low. To follow future trends in prevalence of pAmpC worldwide, a standardized screening algorithm for the detection of pAmpC is needed.

Effectiveness of daily chlorhexidine bathing for reducing gram-negative infections: A meta-analysis

OBJECTIVE

Multiple studies have demonstrated that daily chlorhexidine gluconate (CHG) bathing is associated with a significant reduction in infections caused by gram-positive pathogens. However, there are limited data on the effectiveness of daily CHG bathing on gram-negative infections. The aim of this study was to determine whether daily CHG bathing is effective in reducing the rate of gram-negative infections in adult intensive care unit (ICU) patients.

DESIGN

We searched MEDLINE and 3 other databases for original studies comparing daily bathing with and without CHG. Two investigators extracted data independently on baseline characteristics, study design, form and concentration of CHG, incidence, and outcomes related to gram-negative infections. Data were combined using a random-effects model and pooled relative risk ratios (RRs), and 95% confidence intervals (CIs) were derived.

RESULTS

In total, 15 studies (n = 34,895 patients) met inclusion criteria. Daily CHG bathing was not significantly associated with a lower risk of gram-negative infections compared with controls (RR, 0.89; 95% CI, 0.73-1.08; P = .24). Subgroup analysis demonstrated that daily CHG bathing was not effective for reducing the risk of gram-negative infections caused by Acinetobacter, Escherichia coli, Klebsiella, Enterobacter, or Pseudomonas spp.

CONCLUSIONS

The use of daily CHG bathing was not associated with a lower risk of gram-negative infections. Further, better designed trials with adequate power and with gram-negative infections as the primary end point are needed.

Prevalence of Intestinal Parasitic Infection in Cancer, Organ Transplant and Primary Immunodeficiency Patients in Tehran, Iran

Background:

Intestinal parasitic infection in immunodeficient patients especially those with impaired cellular immunity, like neoplasia, renal or heart transplant needs careful consideration. The objective of this study is to evaluate the prevalence of intestinal parasites in different group of patients including cancer patients; organ transplants recipients, and primary immunodeficiency patients.

Methods:

Stool samples from 190 patients including 80 patients with Primary Immunodeficiency, 85 cancer patients and 25 organ transplant recipients were collected; a direct examination with Phosphate buffered saline (PBS) and formalin ether concentration was performed. The DNA was extracted from parasitologically confirmed patients and nested PCR and sequencing was performed and new obtained sequences of Cryptosporidium parvum and Enterocytozoon bieneusi were compared with deposited ones.

Results:

In general, the prevalence of parasites was 26/80 (32.5%) in primary immunodeficiency, 22/85(25.9%) in cancer group, and 7/25 (28%) in organ transplant. The prevalence of intestinal parasitic infections in primary immunodeficiency patients were Blastocystis hominis 13 (16.2%), Giardia lamblia 10 (12.5%), Cryptosporidium 1(1.2%), Chilomastix mesnilii 1 (1.2%), Dientamoeba fragilis 1(1.2%). Of 25 organ transplants, 6 (24%) Cryptosporidium sp were found, all of which were confirmed as Cryptosporidium parvum and one case of Microspora in a heart transplant recipient was confirmed as Enterocytozoon bieneusi by PCR sequencing. The predominant intestinal parasitic infection in cancer patients was 19 (22.3%) Blastocystis hominis followed by two (2.3%) Giardia lamblia and one Dientamoeba fragilis 1 (1.1%).

Conclusion:

The high rate of infection with Blastocystis hominis was found in cancer patients especially colorectal cancer patients, so careful consideration should be given by physicians. Cryptosporidium sp was found to be the major cause of parasitic intestinal infection in patients with organ transplant compared to primary immunodeficiency patients; so transplant recipients undergoing immunosuppressive therapy should be considered as a risk group for acquiring microsporidiosis and Cryptosporidium infection.

Herpes Simplex Virus Type 2 Immediate Early Protein ICP27 Inhibits IFN-β Production in Mucosal Epithelial Cells by Antagonizing IRF3 Activation

Herpes simplex virus type 2 (HSV-2) is the main cause of genital herpes and infections are common in the lower genital tract. Although neuronal and immune cells can be infected, epithelial cells, and keratinocytes are the primary HSV-2 target cells. HSV-2 establishes latency by evading the host immune system and its infection can also increase the risk of HIV-1 sexual transmission. Our pervious study found that HSV-2 immediate early protein ICP22, inhibited IFN-β production by interfering with the IRF3 pathway. However, ICP22-null HSV-2 did not completely lose the capability of suppressing IFN-β induction, suggesting the involvement of other viral components in the process. In this study, by using an ex vivo cervical explant model, we first demonstrated that HSV-2 can indeed inhibit IFN-β induction in human mucosal tissues. We further identified HSV-2 immediate early protein ICP27 as a potent IFN-β antagonist. ICP27 significantly suppresses the Sendai virus or polyinosinic-polycytidylic acid-induced IFN-β production in human mucosal epithelial cells, showing that ICP27 inhibits the IFN-β promoter activation, and IFN-β production at both mRNA and protein levels. Additional studies revealed that ICP27 directly associates with IRF3 and inhibits its phosphorylation and nuclear translocation, resulting in the inhibition of IFN-β induction. Our findings provide insights into the molecular mechanism underlying HSV-2 mucosal immune evasion, and information for the design of HSV-2 mucosal vaccines.

Human cord blood-derived viral pathogens as the potential threats to the hematopoietic stem cell transplantation safety: A mini review

Umbilical cord blood (UCB) is a valuable source of hematopoietic stem cells (HSCs) and potential alternative for bone marrow transplantation for patients who lack human leukocyte antigen (HLA)-matched donors. The main practical advantages of UCB over other HSC sources are the immediate availability, lower incidence of graft-versus-host disease, minimal risk to the donor, and lower requirement for HLA compatibility. However, the use of UCB is limited by delayed engraftment and poor immune reconstitution, leading to a high rate of infection-related mortality. Therefore, severe infectious complications, especially due to viral pathogens remain the leading cause of morbidity and mortality during the post-UCB transplantation (UCBT) period. In this context, careful screening and excluding the viral-contaminated UCB units might be an effective policy to reduce the rate of UCBT-related infection and mortality. Taken together, complete prevention of the transmission of donor-derived viral pathogens in stem cell transplantation is not possible. However, having the knowledge of the transmission route and prevalence of viruses will improve the safety of transplantation. To the best of our knowledge, there are few studies that focused on the risk of virus transmission through the UCB transplant compared to other HSC sources. This review summarizes the general aspects concerning the prevalence, characteristics, and risk factors of viral infections with a focus on the impact of viral pathogens on cord blood transplantation safety.

Effectiveness of Treatments for Ocular Toxoplasmosis

Purpose: To evaluate the effectiveness of treatments for ocular toxoplasmosis (OT).Methods: A review of charts was conducted from patients who experienced an active episode of OT treated at the Federal University of São Paulo and associated sites. OT charts were reviewed to determine treatment effectiveness based on clinical judgment, taking clinical course and outcome into consideration in addition to change in best-corrected visual acuity. Treatment emergent adverse events (TEAEs) were used to assess safety.Results: Overall, 451/1200 patient charts met the inclusion criteria. The most commonly prescribed treatment was trimethoprim + sulfamethoxazole (52.3%) followed by pyrimethamine + sulfadiazine (28%). Treatment was successful in 96.9% of patients. Irrespective of the treatment, active lesions were resolved in 63.9% of patients within 6 weeks. Vision improved in 56.3% of patients. The incidence of TEAEs was low (10%).Conclusions: All treatments were effective for active episodes of OT, with few side effects.

Septic arthritis

Septic arthritis is truly an emergency condition that needs an early diagnosis by appropriate clinical examination/judgment and using fast, available, and accurate radiological imaging and laboratory septic workup. Early diagnosis may prevent complications that may otherwise lead to the patient's disability.

Dose-Dependent Synergistic Interactions of Colistin with Rifampin, Meropenem, and Tigecycline against Carbapenem-Resistant Klebsiella pneumoniae Biofilms

Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) can cause biofilm-related bloodstream infections associated with significant morbidity and mortality worldwide. We investigated the bactericidal activities of colistin (CST), rifampin (RIF), meropenem (MEM), gentamicin (GEN), and tigecycline (TGC) alone and that of CST in combination with RIF, MEM, GEN, or TGC against CR-Kp mature biofilms. Twenty CR-Kp blood isolates were derived from an equal number of bloodstream infections in adult patients. Biofilm formation was assessed by staining with 0.4% crystal violet and measuring the optical density spectrophotometrically at 545 nm. Biofilm damage was measured as the percent reduction of metabolic activity by an XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide salt] assay. The MIC₅₀ for biofilms was determined as the minimum concentration that caused ≥50% bacterial damage compared to that for untreated controls. Antibacterial drug interactions were analyzed by the Bliss independence model. Four of the 20 CR-Kp isolates were biofilm producers. Biofilm MIC₅₀s of CST, RIF, MEM, GEN, and TGC for these isolates were 64, 8, >256, 128, and 8 mg/liter, respectively. Synergistic interactions were observed at 32 to 64 mg/liter of CST combined with 0.25 to 4 mg/liter of RIF, at 32 mg/liter of CST combined with 0.007 to 0.25 mg/liter of MEM, and at 16 to 32 mg/liter of CST combined with 16 to 64 mg/liter of TGC. The synergy was highest for CST plus RIF, with a mean ΔE ± standard error (SE) of 49.87% ± 9.22%, compared to 29.52% ± 4.97% for CST plus MEM (P < 0.001) and 32.44% ± 6.49% for CST plus TGC (P < 0.001). Indifferent results were exhibited by CST plus GEN. None of the combinations exhibited antagonism. These drug interaction findings, especially those for CST with RIF, may be of importance in the treatment of biofilm-related CR-Kp infections.

Endonuclease Activity Inhibition of the NS1 Protein of Parvovirus B19 as a Novel Target for Antiviral Drug Development

Human parvovirus B19 (B19V), a member of the genus Erythroparvovirus of the family Parvoviridae, is a small nonenveloped virus that has a single-stranded DNA (ssDNA) genome of 5.6 kb with two inverted terminal repeats (ITRs). B19V infection often results in severe hematological disorders and fetal death in humans. B19V replication follows a model of rolling hairpin-dependent DNA replication, in which the large nonstructural protein NS1 introduces a site-specific single-strand nick in the viral DNA replication origins, which locate at the ITRs. NS1 executes endonuclease activity through the N-terminal origin-binding domain. Nicking of the viral replication origin is a pivotal step in rolling hairpin-dependent viral DNA replication. Here, we developed a fluorophore-based in vitro nicking assay of the replication origin using the origin-binding domain of NS1 and compared it with the radioactive in vitro nicking assay. We used both assays to screen a set of small-molecule compounds (n = 96) that have potential antinuclease activity. We found that the fluorophore-based in vitro nicking assay demonstrates sensitivity and specificity values as high as those of the radioactive assay. Among the 96 compounds, we identified 8 which have an inhibition of >80% at 10 µM in both the fluorophore-based and radioactive in vitro nicking assays. We further tested 3 compounds that have a flavonoid-like structure and an in vitro 50% inhibitory concentration that fell in the range of 1 to 3 µM. Importantly, they also exhibited inhibition of B19V DNA replication in UT7/Epo-S1 cells and ex vivo-expanded human erythroid progenitor cells.

MexXY Multidrug Efflux System Is More Frequently Overexpressed in Ciprofloxacin Resistant French Clinical Isolates Compared to Hospital Environment Ones

Modulation of the membrane permeability through a decrease in porin-mediated antibiotic entry and/or an increase in antibiotic efflux is one of the resistance mechanisms to antibiotics evolved by Gram-negative bacteria. To assess whether the outer membrane porin OprD and Resistance-Nodulation-Division (RND) efflux pumps were similarly expressed in 33 ciprofloxacin-resistant clinical strains of Pseudomonas aeruginosa and in 30 non-clinical strains originating from the hospital environment (mainly waterborne Pseudomonas aeruginosa), the expression of oprD, mexB, mexF, and mexY genes was investigated. Overall, the expression of oprD was not detected by RT-qPCR in 14 (22%) strains and underexpressed in 35 (56%) more. No significant difference in oprD expression was detected between clinical and non-clinical strains. As for efflux pumps, 23 (70%) of the clinical strains overexpressed at least one of the tested RND genes. Overexpression of mexB, mexF and mexY was detected in 27, 12, and 45% of the clinical strains, respectively. In the 30 non-clinical strains, no overexpression could be found for mexB, mexF, or mexY. On the contrary, a global underexpression of the tested efflux pump genes was recorded. In both clinical and environmental strains, a positive correlation was found between the expressions of oprD and mexB. Similarly, the expressions of oprD and mexF were positively correlated. This result contrasts with the inverse correlation between both MexAB-OprM/MexEF-OprN and OprD previously described in carbapenem-resistant P. aeruginosa strains. The only positive correlation between phenotypic ciprofloxacin minimum inhibitory concentrations (MICs) and the expression of efflux pump gene was witnessed with mexY (analysis on pooled results for clinical and environmental strains). However, in clinical strains, no statistically significant link could be found between the degree of reduction in ciprofloxacin MICs witnessed with Phenylalanine-Arginine β-naphthylamide (PAβN) and the expression of any of the 3 RND genes tested.

Structure, Mechanism, and Inhibition of Aspergillus fumigatus Thioredoxin Reductase

Aspergillus fumigatus infections are associated with high mortality rates and high treatment costs. Limited available antifungals and increasing antifungal resistance highlight an urgent need for new antifungals. Thioredoxin reductase (TrxR) is essential for maintaining redox homeostasis and presents as a promising target for novel antifungals. We show that ebselen [2-phenyl-1,2-benzoselenazol-3(2H)-one] is an inhibitor of A. fumigatus TrxR (K_i = 0.22 μM) and inhibits growth of Aspergillus spp., with in vitro MIC values of 16 to 64 µg/ml. Mass spectrometry analysis demonstrates that ebselen interacts covalently with a catalytic cysteine of TrxR, Cys148. We also present the X-ray crystal structure of A. fumigatus TrxR and use in silico modeling of the enzyme-inhibitor complex to outline key molecular interactions. This provides a scaffold for future design of potent and selective antifungal drugs that target TrxR, improving the potency of ebselen toward inhbition of A. fumigatus growth.

Immune Response of BALB/c Mice toward Putative Calcium Transporter Recombinant Protein of Trichomonas vaginalis

Trichomoniasis is a common sexually transmitted infection caused by Trichomonas vaginalis, which actually does not exist a vaccine for control or prevention. Thus, the identification of new and potent immunogens in T. vaginalis, which can contribute to the development of a vaccine against this parasite, is necessary. Therefore, the aim of this work was to evaluate the potential of a recombinant Transient Receptor Potential-like channel of T. vaginalis (TvTRPV), as a promising immunogen in BALB/c mice. First, TvTRPV was cloned and expressed as a recombinant protein in Escherichia coli BL21 cells and purified by nickel affinity. Next, BALB/c mice were immunized and the antibody levels in mice serum and cytokines from the supernatant of macrophages and from co-culture systems were evaluated. Recombinant TvTRPV triggered high levels of specific total IgG in sera from the immunized mice. Also, a statistically significant increase of cytokines: IL-1β, IL-6, and TNF-α after stimulation with the corresponding antigens in vitro, was identified. Moreover, co-cultures using CD4⁺ T cells from immunized mice were able to identify higher levels of IL-10 and IFN-γ. These results were useful to validate the immunogenicity of TvTRPV in BALB/c mice, where IL-10-IFN-γ-secreting cells could play a role in infection control, supporting the potential of TvTRPV as a promising target for vaccine against T. vaginalis.

Diversity of Anaplasma species in cattle in Mozambique

Although species of Anaplasma are highly prevalent Rickettsiales agents in domestic and wild ruminants with a wide distribution worldwide, few studies have been conducted so far to detect and/or investigate the diversity of these agentsin cattle in Mozambique. In the present study, serological and molecular assays were used to investigate the occurrence of Anaplasma spp. in 219 bovines sampled in the districts of Boane, Magude, Matutuíne, Moamba and Namaacha in Maputo, Mozambique. In the iELISA test for detection ofIgG antibodies to A. marginale, 86.3% (189/219) of the samples were positive. In qPCR assays for the gene msp1β for A. marginale and msp2 for A. phagocytophilum, 97.3% (213/219) and 2.7% (6/219) of the animals were positive, respectively. Two different cPCR protocols based on the 16S rRNA gene showed that 100% of the samples were positive for Anaplasma spp. The DNA sequences obtained were phylogenetically related to A. platys, A. phagocytophilum, Candidatus Anaplasma boleense, A. centrale, A. marginale and A. ovis. Phylogenetic inference based on the msp4 and msp5 genes positioned the obtained sequences in the clade of A. marginale, with evidence of occurrence of 8 and 5 different haplotypes for each gene, respectively. Anaplasma sp. phylogenetically associated with A. platys was evidenced in phylogenetic analyzes based on 16S rRNA and groEL genes. It is concluded that a high diversity of species of Anaplasma spp. occurs in cattle in Mozambique.

Visual and rapid detection of Acinetobacter baumannii by a multiple cross displacement amplification combined with nanoparticles-based biosensor assay

The traditional microbiological methods used for detecting Acinetobacter baumannii were usually time-consuming and labor-intensive. Thus, we sought to establish a novel rapid detecting method for target pathogen. A set of multiple cross displacement amplification (MCDA) primers was designed to recognize 10 different regions of the pgaD gene, which was conservative and specific for the bacterium. In the MCDA system, amplification primers D1 and R1 were 5'-labeled with FITC (fluorescein) and biotin, respectively. Numerous FITC- and biotin-attached duplex amplicons were formed during the amplification stage, which were detected by nanoparticles-based lateral flow biosensors (LFB) through immunoreactions (FITC on the duplex and anti-FITC on the LFB test line) and biotin/streptavidin interaction (biotin on the duplex and streptavidin on the nanoparticles). The results showed that the optimized reaction condition of MCDA-LFB method was 62 °C within 25 min. There was no cross reaction with non-A. baumannii species and the non-Acinetobacter genera, and the detection limit for DNA samples was 100 fg/reaction. For 135 sputum samples, the detection results showed that the detection ability of MCDA-LFB assay was superior to the culture methods and conventional PCR. Therefore, MCDA-LFB assay could be a potential tool for the rapid detection of A. baumannii in clinical samples and low resource areas.

Clonal change of methicillin-resistant Staphylococcus aureus isolated from patients with impetigo in Kagawa, Japan

Recently, the USA300 clone, which is a Panton-Valentine leukocidin (PVL)-positive clonal complex 8-staphylococcal cassette chromosome mec type IV (CC8-IV) community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strain, emerged in community and hospital settings in Japan. Hence, clonal types of CA-MRSA strains are predicted to be changing. Nonetheless, long-term surveillance of CA-MRSA has not been conducted in Japan. Here, we investigated the transition and current status of CA-MRSA strains isolated from outpatients with impetigo; the samples were collected between 2007 and 2016 in Kagawa, Japan. The detection rate (22.8%, 488/2139 strains) of MRSA slightly decreased in these 10 years. Molecular epidemiological analyses showed that the prevalence of the CC89-II clone, which is a typical CA-MRSA genotype of causative agents of impetigo, significantly decreased from 48.0% (48/100 strains) in 2007-2009 to 21.9% (16/73 strains) in 2013-2016. By contrast, a non-USA300 CC8-IV clone, which is a highly pathogenic CA-MRSA/J clone, significantly increased in prevalence from 9.0% (9/100 strains) to 32.9% (24/73 strains). The prevalence of PVL-positive CA-MRSA strains increased annually from 2012 (0%) to 2015 (6.7%), whereas only one of these strains turned out to be the USA300 clone. Antibiotic susceptibility data revealed that the rates of resistance to gentamicin and clindamycin among CA-MRSA strains decreased along with the decreased prevalence of the CC89-II clone and increased prevalence of the CA-MRSA/J clone. Our data strongly suggest that the clonal types and antibiotic susceptibility of CA-MRSA isolated from patients with impetigo dramatically changed during the last 10 years in Japan.

Nanozymes: Classification, Catalytic Mechanisms, Activity Regulation, and Applications

Because of the high catalytic activities and substrate specificity, natural enzymes have been widely used in industrial, medical, and biological fields, etc. Although promising, they often suffer from intrinsic shortcomings such as high cost, low operational stability, and difficulties of recycling. To overcome these shortcomings, researchers have been devoted to the exploration of artificial enzyme mimics for a long time. Since the discovery of ferromagnetic nanoparticles with intrinsic horseradish peroxidase-like activity in 2007, a large amount of studies on nanozymes have been constantly emerging in the next decade. Nanozymes are one kind of nanomaterials with enzymatic catalytic properties. Compared with natural enzymes, nanozymes have the advantages such as low cost, high stability and durability, which have been widely used in industrial, medical, and biological fields. A thorough understanding of the possible catalytic mechanisms will contribute to the development of novel and high-efficient nanozymes, and the rational regulations of the activities of nanozymes are of great significance. In this review, we systematically introduce the classification, catalytic mechanism, activity regulation as well as recent research progress of nanozymes in the field of biosensing, environmental protection, and disease treatments, etc. in the past years. We also propose the current challenges of nanozymes as well as their future research focus. We anticipate this review may be of significance for the field to understand the properties of nanozymes and the development of novel nanomaterials with enzyme mimicking activities.

Molecular relatedness of ESBL/AmpC-producing Escherichia coli from humans, animals, food and the environment: a pooled analysis

Background

In recent years, ESBL/AmpC-producing Escherichia coli (ESBL/AmpC-EC) have been isolated with increasing frequency from animals, food, environmental sources and humans. With incomplete and scattered evidence, the contribution to the human carriage burden from these reservoirs remains unclear.

Objectives

To quantify molecular similarities between different reservoirs as a first step towards risk attribution.

Methods

Pooled data on ESBL/AmpC-EC isolates were recovered from 35 studies in the Netherlands comprising >27 000 samples, mostly obtained between 2005 and 2015. Frequency distributions of ESBL/AmpC genes from 5808 isolates and replicons of ESBL/AmpC-carrying plasmids from 812 isolates were compared across 22 reservoirs through proportional similarity indices (PSIs) and principal component analyses (PCAs).

Results

Predominant ESBL/AmpC genes were identified in each reservoir. PCAs and PSIs revealed close human-animal ESBL/AmpC gene similarity between human farming communities and their animals (broilers and pigs) (PSIs from 0.8 to 0.9). Isolates from people in the general population had higher similarities to those from human clinical settings, surface and sewage water and wild birds (0.7-0.8), while similarities to livestock or food reservoirs were lower (0.3-0.6). Based on rarefaction curves, people in the general population had more diversity in ESBL/AmpC genes and plasmid replicon types than those in other reservoirs.

Conclusions

Our 'One Health' approach provides an integrated evaluation of the molecular relatedness of ESBL/AmpC-EC from numerous sources. The analysis showed distinguishable ESBL/AmpC-EC transmission cycles in different hosts and failed to demonstrate a close epidemiological linkage of ESBL/AmpC genes and plasmid replicon types between livestock farms and people in the general population.

Burkholderia pseudomallei Lipopolysaccharide Genotype Does Not Correlate With Severity or Outcome in Melioidosis: Host Risk Factors Remain the Critical Determinant

Background

The causative agent of melioidosis is the Gram-negative bacterium Burkholderia pseudomallei. Clinical presentations of melioidosis are notably diverse, with host risk factors considered central to progression from infection to disease and clinical outcome. Ubiquitous and variably present virulence determinants have been described for B pseudomallei, with several variably present minority genotypes associated with specific disease presentations. The lipopolysaccharide (LPS) O-antigen of B pseudomallei is highly diverse with 3 types described. In vitro data suggest differential virulence between LPS types, but it remains unclear whether this LPS O-antigen diversity influences clinical presentation, severity, and outcomes in patients with melioidosis.

Methods

Whole-genome sequencing was performed to assign an LPS type to 1005 consecutive B pseudomallei strains, each corresponding to a melioidosis patient enrolled in the 28-year Darwin Prospective Melioidosis study. Correlations of LPS genotype with clinical parameters was then undertaken.

Results

Bivariate analysis demonstrated that mortality and the rates of bacteremia and septic shock were the same for patients with the 2 predominant B pseudomallei LPS genotypes A (87% of cases) and B (12% of all cases). Mortality was 12% and 12%, bacteremia was 57% and 53%, and septic shock was 22% and 18% for LPS A and LPS B, respectively.

Conclusions

Lipopolysaccharide genotype was not associated with melioidosis severity or outcome. These findings suggest that in vitro differential virulence between B pseudomallei LPS genotypes does not translate to clinical significance, and this supports the primary role of host risk factors in determining disease severity and outcomes in melioidosis.

Mutations in MetG (methionyl-tRNA synthetase) and TrmD [tRNA (guanine-N1)-methyltransferase] conferring meropenem tolerance in Burkholderia thailandensis

Objectives

Although meropenem is widely used to treat Burkholderia infections, the response of Burkholderia pathogens to this antibiotic is largely unexplored.

Methods

Burkholderia thailandensis, a model for Burkholderia spp., particularly Burkholderia mallei and Burkholderia pseudomallei, was challenged with a lethal level of meropenem and survivors were isolated. The genomes of two of the isolates were analysed to identify mutated genes and these genes were then specifically examined in more isolates to profile mutation diversity. Mutants were characterized to investigate the biological basis underlying survival against meropenem.

Results

One of two genes associated with tRNA metabolism [metG or trmD, encoding methionyl-tRNA synthetase or tRNA (guanine-N1)-methyltransferase, respectively] was found to be mutated in the two survivors. A single nucleotide substitution and a frameshift mutation were found in metG and trmD, respectively. Five different substitution mutations affecting methionine- or tRNA-binding sites were found in metG during further screening. The mutants exhibited slowed growth and increased tolerance not only to meropenem but also various other antibiotics. This tolerance required intact RelA, a key stringent response.

Conclusions

Specific mutations affecting the tRNA pool, particularly those in metG, play a pivotal role in the B. thailandensis response to meropenem challenge. This mechanism of antibiotic tolerance is important because it can reduce the effectiveness of meropenem and thereby facilitate chronic infection by Burkholderia pathogens. In addition, specific mutations found in MetG will prove useful in the effort to develop new drugs to completely inhibit this essential enzyme, while preventing stringent-response-mediated antibiotic tolerance in pathogens.

Evaluation of immune response to hepatitis B vaccine in healthcare workers at a tertiary care hospital

Purpose

Healthcare workers (HCWs) are at high risk of acquiring hepatitis B virus (HBV) infection through occupational exposure which is preventable through hepatitis B vaccination. In the current study, the response to HBV surface antigen (HBsAg) vaccine was assessed in a selected group of HCWs by testing for antibodies against HBsAg (anti-HBs).

Methods

Blood samples were collected in all HCWs, who have received the complete schedule of hepatitis B vaccination and anti-HBs levels, were assessed quantitatively in sera using ELISA.

Results

The age range of the study participants was 20-55 years. The mean months after the last dose of vaccination were 60.36. Among the 85 participants, 96.5% (n = 82) have protective immunity to hepatitis B. The anti-Hbs response was similar in both male and female (P > 0.05). There was a decline in immune response as the age was increasing (P < 0.05). The results of the study found a significant decline in the immune response with time (P < 0.05). The anti-Hbs response was declined with smoking habit (P < 0.05) and with increasing body mass index (P < 0.05).

Conclusion

Post-HBsAg vaccination immunity to hepatitis B was 96.5% in HCW and was similar to that of global rates. Increasing age, time period, smoking habit, and overweight were associated with decreased immunity. Many studies are needed in developing newer HBV vaccines with very high immunogenicity. Giving highly immunogenic vaccine to HCWs will ensure safety at work by reducing nosocomial transmission which is very much desired in a resource-limited country.

Reconstruction of Carpal Bone Loss of Septic Wrist Arthritis Using Induced Membrane Technique

The induced membrane technique has been widely used for the reconstruction of the segmental bone defect. The technique requires two-stage surgery. The first surgery is debridement of the affected bone and replacement of the defect by cement spacer. The spacer is removed at the second surgery, and the defect is filled with cancellous bone. The use of the technique for septic wrist arthritis treatment has not been reported. We report two cases of septic wrist arthritis treated by the induced membrane technique. Radical debridement including the carpal bones was performed as a first surgery. The cement spacer was placed into the bone defect after first surgery; then cancellous bone was transplanted into the induced membrane several weeks later. External fixator or plate fixation was performed simultaneously. Bone formation was observed in both cases at several months after the reconstruction surgery. There was no pain or recurrence of infection in both cases. We consider this technique is a possible method for reconstruction, especially in a difficult case.

Newer β-Lactam/β-Lactamase inhibitor for multidrug-resistant gram-negative infections: Challenges, implications and surveillance strategy for India

Antimicrobial resistance (AMR) is a major public health concern across the globe, and it is increasing at an alarming rate. Multiple classes of antimicrobials have been used for the treatment of infectious diseases. Rise in the AMR limits its use and hence the prerequisite for the newer agents to combat drug resistance. Among the infections caused by Gram-negative organisms, beta-lactams are one of the most commonly used agents. However, the presence of diverse beta-lactamases hinders its use for therapy. To overcome these enzymes, beta-lactamase inhibitors are being discovered. The aim of this document is to address the burden of AMR in India and interventions to fight against this battle. This document addresses and summarises the following: The current scenario of AMR in India (antimicrobial susceptibility, resistance mechanisms and molecular epidemiology of common pathogens); contentious issues in the use of beta-lactam/beta-lactamase inhibitor as an carbapenem sparing agent; role of newer beta-lactam/beta-lactamase inhibitor agents with its appropriateness to Indian scenario and; the Indian Council of Medical Research interventions to combat drug resistance in terms of surveillance and infection control as a national response to AMR. This document evidences the need for improved national surveillance system and country-specific newer agents to fight against the AMR.

Enhancement of Cytomegalovirus-Specific Cytokine Production after Modulation of the Costimulation in Kidney Transplant Patients

Kidney transplantation is the therapy of choice for patients with end stage renal disease. Due to immunosuppressive treatment, patients are at risk for opportunistic infections. Cytomegalovirus (CMV) reactivation is highly relevant in kidney transplant recipients because it occurs—depending on the serological constellation of the donor and recipient—in more than half of the patients and influences patient outcome. Patients with CMV reactivation show decreased allograft and overall survival. Previous studies could demonstrate that transplant patients often show weak CMV-specific immunity. Besides immunosuppressive treatment, additional mechanisms may reduce CMV-specific immunocompetence such as enhanced negative costimulation. Hence, the aim of this study was to investigate if the function of CMV-specific cells of kidney transplant recipients could be restored by a modulation of costimulatory molecules. To address this question, lymphocytes of kidney transplant patients were stimulated with CMV-specific antigens and incubated with programmed death-ligand 1 (PD-L1), programmed cell death protein 1 (PD-1), or B- and T-lymphocyte attenuator (BTLA) antibodies. Afterwards, the IFN-γ, IL-21, and IL-17A production was measured by the ELISpot assay. It could be shown that a blockade of the ligand PD-L1 resulted in an increased CMV-specific IFN-γ, IL-21, and IL-17A secretion. The blockade of the receptor PD-1 distinctly enhanced the production of IL-21. BTLA antibodies, however, led only to a marginal increase of CMV-specific IFN-γ and of IL-21 production. Experiments in healthy controls could confirm the results of the kidney transplant recipients. Furthermore, they could demonstrate that treatment with the immunosuppressive drug tacrolimus resulted in decreased CMV-specific IFN-γ and of IL-21 production. Thus, our study could show for the first time that the blockade of the PD-L1/PD-1 pathway also modulates CMV-specific Th21 and Th17 cell function in kidney transplant recipients. Further studies are mandatory to clarify the role of Th21 and Th17 cells in CMV control of these patients.

Genomic epidemiology and antimicrobial resistance of Neisseria gonorrhoeae in New Zealand

Background

Antimicrobial-resistant Neisseria gonorrhoeae is a major threat to public health. No studies to date have examined the genomic epidemiology of gonorrhoea in the Western Pacific Region, where the incidence of gonorrhoea is particularly high.

Methods

A population-level study of N. gonorrhoeae in New Zealand (October 2014 to May 2015). Comprehensive susceptibility testing and WGS data were obtained for 398 isolates. Relatedness was inferred using phylogenetic trees, and pairwise core SNPs. Mutations and genes known to be associated with resistance were identified, and correlated with phenotype.

Results

Eleven clusters were identified. In six of these clusters, >25% of isolates were from females, while in eight of them, >15% of isolates were from females. Drug resistance was common; 98%, 32% and 68% of isolates were non-susceptible to penicillin, ciprofloxacin and tetracycline, respectively. Elevated MICs to extended-spectrum cephalosporins (ESCs) were observed in 3.5% of isolates (cefixime MICs ≥ 0.12 mg/L, ceftriaxone MICs ≥ 0.06 mg/L). Only nine isolates had penA XXXIV genotypes, three of which had decreased susceptibility to ESCs (MIC = 0.12 mg/L). Azithromycin non-susceptibility was identified in 43 isolates (10.8%); two of these isolates had 23S mutations (C2611T, 4/4 alleles), while all had mutations in mtrR or its promoter.

Conclusions

The high proportion of females in clusters suggests transmission is not exclusively among MSM in New Zealand; re-assessment of risk factors for transmission may be warranted in this context. As elevated MICs of ESCs and/or azithromycin were found in closely related strains, targeted public health interventions to halt transmission are urgently needed.

Anticoccidial efficacy of Canary rue (Ruta pinnata) extracts against the caprine apicomplexan Eimeria ninakohlyakimovae

Continuous use of anticoccidial treatments against Eimeria infections has resulted in the development of drug resistance. This study aimed to evaluate the anticoccidial efficacy of a methanolic extract derived from the endemic Canary rue (Ruta pinnata) plant of the Canary Islands, Spain, against Eimeria ninakohlyakimovae using in vitro assays. Freshly unsporulated oocysts were exposed to different concentrations of R. pinnata extract and thereafter evaluated for sporulation inhibition. Additionally, anticoccidial activity was examined by testing the viability of the E. ninakohlyakimovae sporozoites and their ability to infect bovine colonic epithelial cells after incubation with different concentrations of R. pinnata plant extract. The inhibition of oocyst sporulation by the extract was both time and concentration dependent, with certain combinations affording the same levels of sporulation inhibition as formaldehyde used as positive control (P < 0.001). Moreover, concentrations >0.1 mg/mL also affected not only the viability of the sporozoites but also their cell invasion capacity (P < 0.001). Altogether, these results show that methanolic fruit extracts from R. pinnata have important anticoccidial activity against oocysts and sporozoites of Eimeria. The potential efficacy of the extracts against other animal/human parasites remains to be elucidated, and further studies are needed to better understand its mode of action against coccidian parasites.

Active antimicrobial efflux in Staphylococcus epidermidis: building up of resistance to fluoroquinolones and biocides in a major opportunistic pathogen

Objectives

To analyse the efflux-mediated response of Staphylococcus epidermidis to ethidium bromide (EtBr), a substrate of multidrug efflux pumps (EPs).

Methods

The susceptible reference strain S. epidermidis ATCC 12228 was exposed to a step-wise adaptation to EtBr. The resulting EtBr-adapted strains were characterized regarding their antibiotic and biocide susceptibility by MIC determination and evaluation of efflux activity by re-determination of MICs in the presence of known efflux inhibitors and real-time fluorometry. Mutations in the QRDR of grlA and gyrA were screened by sequencing. The expression levels of S. epidermidis homologues of the main Staphylococcus aureus EP genes were quantified by RT-qPCR.

Results

Exposure to EtBr led to a gradual increase in resistance to antimicrobials, with the final EtBr-adapted strain, ATCC 12228_EtBr, displaying phenotypic resistance to fluoroquinolones and reduced susceptibility to several antiseptics and disinfectants, although no mutations were detected in the QRDR of the grlA/gyrA genes. A reduction in the MICs of fluoroquinolones and selected biocides promoted by efflux inhibitors suggested an efflux-mediated response to EtBr exposure. Detailed analysis of the EtBr-adapted strains detected a gradual increase in efflux activity. Gene expression assays revealed a temporal activation of S. epidermidis EPs, with an early response involving norA, SE2010 and SE1103 followed by a late response mediated by norA, which coincided with the occurrence of the mutation -1A→T in the norA promoter region.

Conclusions

This study demonstrated that S. epidermidis has the potential to develop a multiple resistance phenotype mediated by efflux when exposed to a non-antibiotic substrate of multidrug EPs.

Detection of Ureaplasma spp. serovars in genital tract of infertile males

BACKGROUND

The colonization of Ureaplasma species in genital tract is related with male infertility. However, it has been postulated based upon limited study that virulence is related to serotype specificity. The aim of this study was to determine the distribution of Ureaplasma serovars in genital tract of infertile males and analyze their role in male infertility.

METHODS

A total of 358 urethral swabs samples were obtained from infertile males. The culture of Ureaplasma species were performed using a commercially available Mycoplasma IST 2 kit. Serovars were determined by real-time polymerase chain reaction (real-time PCR).

RESULTS

A total of 92 (25.7%) infertile males were positive for Ureaplasma spp; among them, Ureaplasma parvum (UPA) was detected in 73 (79.3%) isolates, and Ureaplasma urealyticum (UUR) was detected in 19 (20.7%) isolates. Serovars 1, 6, or in combination accounted for 63.0% (46/73) of UPA isolates. Serovar 9 (alone and in combination of other serovars) was the most common serovar in UUR (47.4%, 9/19). Multiple serovars were detected in 21 (22.8%) isolates, and serovars 4, 5, 7, and 12 were not detected in any sample.

CONCLUSION

The distribution of 14 Ureaplasma serovars in genital tract of infertile males was identified for the first time by real-time PCR assay. UPA serovars 1 and 6, and UUR serovar 9 are the most common serovars colonization in urogenital tract of infertile males.

Dengue virus nonstructural 3 protein interacts directly with human glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and reduces its glycolytic activity

Dengue is an important mosquito-borne disease and a global public health problem. The disease is caused by dengue virus (DENV), which is a member of the Flaviviridae family and contains a positive single-stranded RNA genome that encodes a single precursor polyprotein that is further cleaved into structural and non-structural proteins. Among these proteins, the non-structural 3 (NS3) protein is very important because it forms a non-covalent complex with the NS2B cofactor, thereby forming the functional viral protease. NS3 also contains a C-terminal ATPase/helicase domain that is essential for RNA replication. Here, we identified 47 NS3-interacting partners using the yeast two-hybrid system. Among those partners, we highlight several proteins involved in host energy metabolism, such as apolipoprotein H, aldolase B, cytochrome C oxidase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH directly binds full-length NS3 and its isolated helicase and protease domains. Moreover, we observed an intense colocalization between the GAPDH and NS3 proteins in DENV2-infected Huh7.5.1 cells, in NS3-transfected BHK-21 cells and in hepatic tissue from a fatal dengue case. Taken together, these results suggest that the human GAPDH-DENV NS3 interaction is involved in hepatic metabolic alterations, which may contribute to the appearance of steatosis in dengue-infected patients. The interaction between GAPDH and full-length NS3 or its helicase domain in vitro as well as in NS3-transfected cells resulted in decreased GAPDH glycolytic activity. Reduced GAPDH glycolytic activity may lead to the accumulation of metabolic intermediates, shifting metabolism to alternative, non-glycolytic pathways. This report is the first to identify the interaction of the DENV2 NS3 protein with the GAPDH protein and to demonstrate that this interaction may play an important role in the molecular mechanism that triggers hepatic alterations.