A Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology

Applications of Digital Microscopy and Densely Connected Convolutional Neural Networks for Automated Quantification of Babesia-Infected Erythrocytes

BACKGROUND

Clinical babesiosis is diagnosed, and parasite burden is determined, by microscopic inspection of a thick or thin Giemsa-stained peripheral blood smear. However, quantitative analysis by manual microscopy is subject to error. As such, methods for the automated measurement of percent parasitemia in digital microscopic images of peripheral blood smears could improve clinical accuracy, relative to the predicate method.

METHODS

Individual erythrocyte images were manually labeled as "parasite" or "normal" and were used to train a model for binary image classification. The best model was then used to calculate percent parasitemia from a clinical validation dataset, and values were compared to a clinical reference value. Lastly, model interpretability was examined using an integrated gradient to identify pixels most likely to influence classification decisions.

RESULTS

The precision and recall of the model during development testing were 0.92 and 1.00, respectively. In clinical validation, the model returned increasing positive signal with increasing mean reference value. However, there were 2 highly erroneous false positive values returned by the model. Further, the model incorrectly assessed 3 cases well above the clinical threshold of 10%. The integrated gradient suggested potential sources of false positives including rouleaux formations, cell boundaries, and precipitate as deterministic factors in negative erythrocyte images.

CONCLUSIONS

While the model demonstrated highly accurate single cell classification and correctly assessed most slides, several false positives were highly incorrect. This project highlights the need for integrated testing of machine learning-based models, even when models in the development phase perform well.

Clinical evaluation of nasopharyngeal, midturbinate nasal and oropharyngeal swabs for the detection of SARS-CoV-2

In the setting of supply chain shortages of nasopharyngeal (NP) swabs, we sought to compare the ability of nasopharyngeal, midturbinate nasal, and oropharyngeal swabs (NPS, MTS, and OPS) to detect SARS-CoV-2. Community and hospitalized participants post-COVID-19 diagnosis were swabbed and tested for SARS-CoV-2 by PCR. Thirty-six participants had all 3 swabs collected. Using detection at any site as the standard, the percent positive agreements were 90% (95% CI 74.4−96.5), 80% (70.3−94.7) and 87% (62.7−90.5) for NPS, MTS, and OPS, respectively. Subsequently, 43 participants had OPS and NPS collected. Thirty-nine were positive with a percent positive agreement of 82.1% (95% CI 67.3−91.0) for OPS and 87.2% (73.3−94.4) for NPS. Combining all 79 patients tested, 67 were positive at either site with a positive agreement was 86.5% (76.4−92.7) for OPS and 91.1% (81.8−95.8) for NPS. OPS are an acceptable alternative to NPS for the detection of SARS-CoV-2 infections.

Development of an intelligent, stimuli-responsive transdermal system for efficient delivery of Ibuprofen against rheumatoid arthritis

The present study aimed to fabricate and evaluate the therapeutic efficacy of pH-responsive Ibuprofen (IB) nanoparticles (NPs) loaded transdermal hydrogel against rheumatoid arthritis (RA). The IB loaded Eudragit® L 100 (EL 100) nanoparticles were formulated through a modified nanoprecipitation technique and optimized using central composite design software. The optimized NPs were loaded into Carbopol® 934-based hydrogel by solvent evaporation method and were analyzed for physicochemical characteristics. The mean particle size of the prepared NPs was 48 nm with an entrapment efficiency of 90%. The transdermal hydrogel showed a pH-responsive sustained drug release and high penetration through the skin. Moreover, the prepared nanocarrier system exhibited therapeutic efficacy at inflamed joints' sites both in acute and chronic RA mice model. The therapeutic efficacy of the prepared formulation was confirmed through the results of various behavioral, biochemical, and cytokines-based assays. Similarly, the assessment of histopathological and radiological images, as well as the skin irritation studies further strengthens the potential use of the prepared formulation through the transdermal route. The current findings suggested that IB loaded pH-responsive NPs based transdermal hydrogel can be used as an efficient agent to manage RA.

Microbes, Clinical trials, Drug Discovery, and Vaccine Development: The Current Perspectives

Because of the frequent emergence of novel microbial species and the re-emergence of genetic variants of hitherto known microbes, the global healthcare system, and human health has been thrown into jeopardy. Also, certain microbes that possess the ability to develop multi-drug resistance (MDR) have limited the treatment options in cases of serious infections, and increased hospital and treatment costs, and associated morbidity and mortality. The recent discovery of the novel Coronavirus (n-CoV), the Severe Acute Respiratory Syndrome CoV-2 (SARS-CoV-2) that is causing the CoV Disease-19 (COVID-19) has resulted in severe morbidity and mortality throughout the world affecting normal human lives. The major concern with the current pandemic is the non-availability of specific drugs and an incomplete understanding of the pathobiology of the virus. It is therefore important for pharmaceutical establishments to envisage the discovery of therapeutic interventions and potential vaccines against the novel and MDR microbes. Therefore, this review is attempted to update and explore the current perspectives in microbes, clinical research, drug discovery, and vaccine development to effectively combat the emerging novel and re-emerging genetic variants of microbes.

Diagnostic Stewardship: Appropriate Testing and Judicious Treatments

Diagnostic stewardship encompasses the entire diagnosis-to-treatment paradigm in the intensive care unit (ICU). Initially born of the antimicrobial stewardship movement, contemporary diagnostic stewardship aims to promote timely and appropriate diagnostic testing that directly links to management decisions. In the stewardship framework, excessive diagnostic testing in low probability cases is discouraged due to its tendency to generate false-positive results, which have their own downstream consequences. Though the evidence basis for diagnostic stewardship initiatives in the ICU is nascent and largely limited to retrospective analyses, available literature generally suggests that these initiatives are safe, feasible, and associated with similar patient outcomes. As diagnostic testing of critically ill patients becomes increasingly sophisticated in the ensuing decade, a stewardship mindset will aid bedside clinicians in interpreting and incorporating new diagnostic strategies in the ICU.

Case of infant invasive Streptococcus intermedius infection suggesting the need for anaerobic cultures

We report the case of an immunocompetent 6-month-old boy with a lung abscess and empyema caused by Streptococcus intermedius detected only from anaerobic cultures. Invasive S. intermedius infection in infants is rare. S. intermedius has been infrequently reported as a causative microorganism of lung abscess and empyema as most of the S. intermedius infections in children have been head and neck infections. While anaerobic cultures are often not performed for infant patients, we suggest the need for these cultures, including blood cultures, especially in cases of pediatric empyema, brain abscess, and liver abscess, which can be caused by S. intermedius.

The influence of sample processing time on the performance of Microsporum canis cultures in cats

BACKGROUND

Fungal culture is widely used as a diagnostic tool for detecting dermatophytosis. However, the presence of fungal contaminants can influence the culture's performance and compromise the diagnosis.

OBJECTIVE

To verify whether the sample processing time can affect the performance of fungal culture for the diagnosis of Microsporum canis infection in cats.

ANIMALS

Forty Persian cats.

METHODS AND MATERIALS

Hair and scale samples were collected by combing the coat using a 5 × 5 cm sterile polyester carpet. The carpets were assigned randomly to four groups based on time point of processing samples after collection (i.e. used for culture on a selective agar medium for dermatophytes): Group 1: 8 h (n = 10); Group 2: 24 h (n = 10); Group 3: 48 h (n = 10); and Group 4: 72 h (n = 10). Cultures were compared regarding the degree of fungal invasion by either M. canis or nondermatophytic contaminant moulds (NDM).

RESULTS

Processing samples after 24 h of storage resulted in increased isolation rates of NDM and decreased isolation rates of M. canis. Samples processed after 48 h and 72 h presented more than half of the plates with a high degree of fungal contamination (i.e. NDM occupying ≥50% of the total fungal mass). However, samples processed after 8 h and 24 h presented a lower degree (P < 0.05) of NDM plate invasion and higher recovery rates of M. canis when compared to samples processed after 48 h and 72 h.

CONCLUSIONS AND CLINICAL IMPORTANCE

Delayed processing time is closely associated with the overgrowth of contaminants and with lower recovery rates of M. canis.

Best practice standards for the delivery of NHS infection services in the United Kingdom

Infection expertise in the NHS has historically been provided predominantly by hospital-based medical microbiologists responsible for provision of diagnostic services and advice to front-line clinicians. While most hospitals had consultant-led microbiology departments, infectious iiseases departments were based in a small number of specialist centres. The demand for infection expertise is growing in the NHS, driven by advances in medical care, increasing awareness of the impact of antibiotic resistant and healthcare associated infections and threats from emerging infectious diseases. At the same time diagnostic services are being reorganised into pathology networks. The Combined Infection Training (CIT) is delivering a consultant workforce with expertise both in laboratory diagnostic practice and delivery of direct patient care. These changes create challenges for delivery of high quality infection expertise equitably across the NHS. They also offer an opportunity to shape infection services to meet clinical and laboratory demands. To date there has not been an attempt to bring together a single set of best practice guidelines for the requirements of an infection service. This document sets out seven standards. These are written to be practical and flexible according to the diverse ways in which infection expertise may be required across the NHS. It has been prepared by the Clinical Services Committee of the British Infection Association drawing on published evidence and guidance where they exist and on the group's extensive experience of delivering infection services in hospitals across the NHS. It was then refined with input from the RCP Joint Specialist committee (JSC) and the RCPath Specialist Advisory Committee (SAC) and through consultation with the RCPath membership. It has been endorsed by the Royal College of Pathologists and the Royal College of Physicians. It will be reviewed annually by the CSC and updated as additional evidence becomes available.

Assessment of a PK/PD Target of Continuous Infusion Beta-Lactams Useful for Preventing Microbiological Failure and/or Resistance Development in Critically Ill Patients Affected by Documented Gram-Negative Infections

BACKGROUND

Emerging data suggest that more aggressive beta-lactam PK/PD targets could minimize the occurrence of microbiological failure and/or resistance development. This study aims to assess whether a PK/PD target threshold of continuous infusion (CI) beta-lactams may be useful in preventing microbiological failure and/or resistance development in critically ill patients affected by documented Gram-negative infections.

METHODS

Patients admitted to intensive care units from December 2020 to July 2021 receiving continuous infusion beta-lactams for documented Gram-negative infections and having at least one therapeutic drug monitoring in the first 72 h of treatment were included. A receiver operating characteristic (ROC) curve analysis was performed using the ratio between steady-state concentration and minimum inhibitory concentration (C_ss/MIC) ratio as the test variable and occurrence of microbiological failure as the state variable. Area under the curve (AUC) and 95% confidence interval (CI) were calculated. Independent risk factors for the occurrence of microbiological failure were investigated using logistic regression.

RESULTS

Overall, 116 patients were included. Microbiological failure occurred in 26 cases (22.4%). A C_ss/MIC ratio ≤ 5 was identified as PK/PD target cut-off with sensitivity of 80.8% (CI 60.6-93.4%) and specificity of 90.5% (CI 74.2-94.4%), and with an AUC of 0.868 (95%CI 0.793-0.924; p < 0.001). At multivariate regression, independent predictors of microbiological failure were C_ss/MIC ratio ≤ 5 (odds ratio [OR] 34.54; 95%CI 7.45-160.11; p < 0.001) and Pseudomonas aeruginosa infection (OR 4.79; 95%CI 1.11-20.79; p = 0.036).

CONCLUSIONS

Early targeting of CI beta-lactams at C_ss/MIC ratio > 5 during the treatment of documented Gram-negative infections may be helpful in preventing microbiological failure and/or resistance development in critically ill patients.

A Retrospective Paired Comparison Between Untargeted Next Generation Sequencing and Conventional Microbiology Tests With Wisely Chosen Metagenomic Sequencing Positive Criteria

Objectives: To evaluate the performance of metagenomic next generation sequencing (mNGS) using adequate criteria for the detection of pathogens in lower respiratory tract (LRT) samples with a paired comparison to conventional microbiology tests (CMT).

Methods: One hundred sixty-seven patients were reviewed from four different intensive care units (ICUs) in mainland China during 2018 with both mNGS and CMT results of LRT samples available. The reads per million ratio (RPM_sample/RPM_{non−template−control} ratio) and standardized strictly mapped reads number (SDSMRN) were the two criteria chosen for identifying positive pathogens reported from mNGS. A McNemar test was used for a paired comparison analysis between mNGS and CMT.

Results: One hundred forty-nine cases were counted into the final analysis. The RPMsample/RPM_NTC ratio criterion performed better with a higher accuracy for bacteria, fungi, and virus than SDSMRN criterion [bacteria (RPMsample/RPM_NTC ratio vs. SDSMRN), 65.1 vs. 55.7%; fungi, 75.8 vs. 71.1%; DNA virus, 86.3 vs. 74.5%; RNA virus, 90.9 vs. 81.8%]. The mNGS was also superior in bacteria detection only if an SDSMRN ≥3 was used as a positive criterion with a paired comparison to culture [SDSMRN positive, 92/149 (61.7%); culture positive, 54/149 (36.2%); p < 0.001]; however, it was outperformed with significantly more fungi and DNA virus identification when choosing both criteria for positive outliers [fungi (RPMsample/RPM_NTC ratio vs. SDSMRN vs. culture), 23.5 vs. 29.5 vs. 8.7%, p < 0.001; DNA virus (RPMsample/RPM_NTC ratio vs. SDSMRN vs. PCR), 14.1 vs. 20.8 vs. 11.8%, p < 0.05].

Conclusions: Metagenomic next generation sequencing may contribute to revealing the LRT infection etiology in hospitalized groups of potential fungal infections and in situations with less access to the multiplex PCR of LRT samples from the laboratory by choosing a wise criterion like the RPMsample/RPM_NTC ratio.

Development and validation of a miniaturized bacteriophage host range screening assay against antibiotic resistant Pseudomonas aeruginosa

Antimicrobial resistance is a current global health crisis, and the increasing emergence of multidrug resistant infections has led to the resurgent interest in bacteriophages as an alternative treatment. Prior to clinical application, phage suitability is assessed, via susceptibility testing and breadth of host range to bacteriophage, however, these are both large-scale manual processes and labor-intensive. The aim of the study was to establish and validate a scaled down methodology for high-throughput screening to reduce procedural footprint. In this paper, we describe a scaled-down adapted methodology that can successfully screen bacteriophages, isolated and purified from wastewater samples. Furthermore, we describe a miniaturized host range assay against clinical Pseudomonas aeruginosa isolates using a spot test (2 μL/ drop) that was found to be both sensitive (94.6%) and specific (94.7%). It also demonstrated a positive predictive value (PPV) of 86.4% and negative predictive value (NPV) of 98%. The breadth of host range of bacteriophages that exhibited lytic activity on P. aeruginosa isolates was corroborated using the scaled down assay. The high correlation achieved in this study confirms miniaturization as the first step in future automation that could test phage diversity and efficacy as antimicrobials.

A Prospective Study to Assess the Optimal Incubation Times for Culture and Aerobic Bacterial Profile in Prosthetic Joint Infections

Introduction With an increase in the number of total joint arthroplasties, the count of prosthetic joint infections (PJIs) is also increasing and has become a nightmare for an orthopaedic surgeon. Microbiological diagnosis is important for administering definitive antimicrobial treatment. Negative culture reports hamper patient management and prolonged incubation periods have increased the culture yield but at the risk of culture contamination in conventional microbiology settings. Thus, we aimed to optimize the best incubation time for culture and the aerobic bacterial profile of PJIs.

Material and Methods Over a year, samples from clinically suspected PJI patients were collected and processed for culture using standard techniques. The samples were incubated for up to 10 days with daily subculturing on to solid media. The bacterial isolates were identified and antibiotic susceptibility was performed.

Results Out of 200 patients, 105 were included in the study and samples were collected in triplicate. In 70 cases culture was positive and 35 were culture negative PJIs. Mean incubation days to culture positivity was 3.6 days with 97.14% culture positivity seen by the seventh day of incubation. Twenty-four percent methicillin-resistant Staphylococcus aureus , and more than 50% extended spectrum β lactamase producing Klebsiella pneumoniae and Escherichia coli were isolated.

Discussion Culture positivity in PJIs provides definitive evidence of infection and guides the treatment. Increasing the incubation times can help in maximizing the culture yield, and we found that 97.14% pathogens grew within 7 days of incubation. Prolonging it further would not provide an added advantage especially in a resource-constraint setting.

Update of the recommendations of the Sociedade Portuguesa de Cuidados Intensivos and the Infection and Sepsis Group for the approach to COVID-19 in Intensive Care Medicine

INTRODUCTION

The Sociedade Portuguesa de Cuidados Intensivos and the Infection and Sepsis Group have previously issued health service and management recommendations for critically ill patients with COVID-19. Due to the evolution of knowledge, the panel of experts was again convened to review the current evidence and issue updated recommendations.

METHODS

A national panel of experts who declared that they had no conflicts of interest regarding the development of the recommendations was assembled. Operational questions were developed based on the PICO methodology, and a rapid systematic review was conducted by consulting different bibliographic sources. The panel determined the direction and strength of the recommendations using two Delphi rounds, conducted in accordance with the principles of the GRADE system. A strong recommendation received the wording "is recommended", and a weak recommendation was written as "is suggested."

RESULTS

A total of 48 recommendations and 30 suggestions were issued, covering the following topics: diagnosis of SARS-CoV-2 infection, coinfection and superinfection; criteria for admission, cure and suspension of isolation; organization of services; personal protective equipment; and respiratory support and other specific therapies (antivirals, immunomodulators and anticoagulation).

CONCLUSION

These recommendations, specifically oriented to the Portuguese reality but that may also apply to Portuguese-speaking African countries and East Timor, aim to support health professionals in the management of critically ill patients with COVID-19. They will be continuously reviewed to reflect the progress of our understanding and the treatment of this pathology.

Neutrophil-to-Lymphocyte Ratios and Infections after Traumatic Brain Injury: Associations with Hospital Resource Utilization and Long-Term Outcome

Traumatic brain injury (TBI) induces immune dysfunction that can be captured clinically by an increase in the neutrophil-to-lymphocyte ratio (NLR). However, few studies have characterized the temporal dynamics of NLR post-TBI and its relationship with hospital-acquired infections (HAI), resource utilization, or outcome. We assessed NLR and HAI over the first 21 days post-injury in adults with moderate-to-severe TBI (n = 196) using group-based trajectory (TRAJ), changepoint, and mixed-effects multivariable regression analysis to characterize temporal dynamics. We identified two groups with unique NLR profiles: a high (n = 67) versus a low (n = 129) TRAJ group. High NLR TRAJ had higher rates (76.12% vs. 55.04%, p = 0.004) and earlier time to infection (p = 0.003). In changepoint-derived day 0–5 and 6–20 epochs, low lymphocyte TRAJ, early in recovery, resulted in more frequent HAIs (p = 0.042), subsequently increasing later NLR levels (p ≤ 0.0001). Both high NLR TRAJ and HAIs increased hospital length of stay (LOS) and days on ventilation (p ≤ 0.05 all), while only high NLR TRAJ significantly increased odds of unfavorable six-month outcome as measured by the Glasgow Outcome Scale (GOS) (p = 0.046) in multivariable regression. These findings provide insight into the temporal dynamics and interrelatedness of immune factors which collectively impact susceptibility to infection and greater hospital resource utilization, as well as influence recovery.

Emerging issue of fluconazole-resistant candidemia in a tertiary care hospital of southern italy: time for antifungal stewardship program

An increased number of patients is at risk of Candida spp. bloodstream infection (CBSI) in modern medicine. Moreover, the rising of antifungal resistance (AR) was recently reported. All consecutive CBSI occurred in our Hospital (consisting of 1,370 beds) between 2015 and 2018, were reviewed. For each case, Candida species, AR pattern, ward involved and demographic data of patients were recorded. Overall, 304 episodes of CBSI occurred, with a median (q1:first-,q3:third quartile) of 77 (71-82) CBSI/year. Over the years, a significant increase of CBSI due to C. albicans compared to non-albicans strains was recorded in medical wards (from 65% to 71%, p=0.030), while this ratio remained stable in others. An increase of resistant strains to multiple antifungals such as C. guillermondii was noticed in recent years (from 0% to 9.8%, p=0.008). Additionally, from 2015 to 2018 an increase in fluconazole-resistance was recorded in our Hospital (from 7.4% to 17.4%, p=0.025) and a slight increase in voriconazole-resistance (from 0% to 7% in 2018, p=0.161) was observed, while resistance to echinocandin and amphotericin B remained firmly below 2%. This study suggests a rapid spread of antifungal resistance in our Hospital; therefore, an appropriate antifungal stewardship programs is urgently warranted.

Clinical Relevance of the Microbiome in Odontogenic Abscesses

Simple Summary

Odontogenic infections are very common. The course of disease ranges from mild to severe and sometimes even life-threatening infections. Optimal therapy is based on rapid abscess incision and, especially in severe cases, on adjuvant antibiotic therapy that ideally targets the culprit bacteria. In order to identify these bacteria, clinicians usually perform cultural analysis from smears of pus and aim for antibiotic susceptibility testing. In recent years, using new molecular methods, it has become possible to carry out a much more detailed analysis of the bacterial colonization of different parts of the human body by determining a microbiome. In our study, we have, for the first time, compared such a microbiome of odontogenic abscesses with cultural bacterial determination carried out in the clinical routine of a university hospital. The key finding of the study is not only that considerably more bacteria can be detected in the abscess in this way but also that easily cultivated bacteria dominate over the actual fastidious pathogenic bacteria. Thus, routine clinical culture probably only provides a distorted picture of reality and should be supplemented by molecular methods in the future.

Abstract

Odontogenic abscesses are usually caused by bacteria of the oral microbiome. However, the diagnostic culture of these bacteria is often prone to errors and sometimes fails completely due to the fastidiousness of the relevant bacterial species. The question arises whether additional pathogen diagnostics using molecular methods provide additional benefits for diagnostics and therapy. Experimental 16S rRNA gene analysis with next-generation sequencing (NGS) and bioinformatics was used to identify the microbiome of the pus in patients with severe odontogenic infections and was compared to the result of standard diagnostic culture. The pus microbiome was determined in 48 hospitalized patients with a severe odontogenic abscess in addition to standard cultural pathogen detection. Cultural detection was possible in 41 (85.42%) of 48 patients, while a pus-microbiome could be determined in all cases. The microbiomes showed polymicrobial infections in 46 (95.83%) cases, while the picture of a mono-infection occurred only twice (4.17%). In most cases, a predominantly anaerobic spectrum with an abundance of bacteria was found in the pus-microbiome, while culture detected mainly Streptococcus, Staphylococcus, and Prevotella spp. The determination of the microbiome of odontogenic abscesses clearly shows a higher number of bacteria and a significantly higher proportion of anaerobes than classical cultural methods. The 16S rRNA gene analysis detects considerably more bacteria than conventional cultural methods, even in culture-negative samples. Molecular methods should be implemented as standards in medical microbiology diagnostics, particularly for the detection of polymicrobial infections with a predominance of anaerobic bacteria.

Consensus Recommendations for Blood Culture Use in Critically Ill Children Using a Modified Delphi Approach

OBJECTIVES

Blood cultures are fundamental in evaluating for sepsis, but excessive cultures can lead to false-positive results and unnecessary antibiotics. Our objective was to create consensus recommendations focusing on when to safely avoid blood cultures in PICU patients.

DESIGN

A panel of 29 multidisciplinary experts engaged in a two-part modified Delphi process. Round 1 consisted of a literature summary and an electronic survey sent to invited participants. In the survey, participants rated a series of recommendations about when to avoid blood cultures on five-point Likert scale. Consensus was achieved for the recommendation(s) if 75% of respondents chose a score of 4 or 5, and these were included in the final recommendations. Any recommendations that did not meet these a priori criteria for consensus were discussed during the in-person expert panel review (Round 2). Round 2 was facilitated by an independent expert in consensus methodology. After a review of the survey results, comments from round 1, and group discussion, the panelists voted on these recommendations in real-time.

SETTING

Experts' institutions; in-person discussion in Baltimore, MD.

SUBJECTS

Experts in pediatric critical care, infectious diseases, nephrology, oncology, and laboratory medicine.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 27 original recommendations, 18 met criteria for achieving consensus in Round 1; some were modified for clarity or condensed from multiple into single recommendations during Round 2. The remaining nine recommendations were discussed and modified until consensus was achieved during Round 2, which had 26 real-time voting participants. The final document contains 19 recommendations.

CONCLUSIONS

Using a modified Delphi process, we created consensus recommendations on when to avoid blood cultures and prevent overuse in the PICU. These recommendations are a critical step in disseminating diagnostic stewardship on a wider scale in critically ill children.

Multiple anatomic sites of infarction in a pediatric patient with M. pneumoniae infection, a case report

Background

Although M. pneumoniae (M. pneumoniae) infections have been associated with various extrapulmonary manifestations, there have been very few documented cases of thrombotic events in pediatrics, and none to our knowledge with such extensive involvement as the patient described here. We aim to contribute to the urgency of discovering the mechanism of the coagulopathy associated with M. pneumoniae infections.

Case presentation

This 10-year-old boy was admitted after 2 weeks of fever, sore throat, worsening cough, and progressive neck and back pain. During hospitalization, he developed clots in several different organs: bilateral pulmonary emboli, cardiac vegetations, multiple splenic infarcts, and deep venous thromboses in three of four extremities. He was treated with long-term antibiotics and anticoagulation, and fully recovered.

Conclusions

This is the first case known to us of a child with an extensive number of thrombotic events in multiple anatomic sites associated with M. pneumoniae infection. The mechanism by which M. pneumoniae infection is related to thrombotic events is not fully understood, but there is evidence that the interplay between the coagulation pathways and the complement cascade may be significant. This patient underwent extensive investigation, and was found to have significant coagulopathy, but minimal complement abnormalities. By better understanding the mechanisms involved in complications of M. pneumoniae infection, the clinician can more effectively investigate the progression of this disease saving time, money, morbidity, and mortality.

Epidemiology of bacteremia in a pediatric population - A 10-year study

INTRODUCTION

With the widespread introduction of conjugate meningococcal and pneumococcal vaccines, the prevalence and etiology of invasive bacterial infections have changed. We aimed to review all cases of bacteremia in a level II pediatric department over a ten-year period in the post-pneumococcal conjugate vaccine era.

METHODS

We reviewed all positive blood cultures (BC) obtained in our department between 2007 and 2016. Results were classified as contaminants, potential pathogens or confirmed pathogens, based on species, number of positive BC in the episode and the patients' medical history. Demographic and clinical data were collected for patients with identified pathogens.

RESULTS

A total of 638 positive BC were identified (6.6% of total BC); 120 (1.2%) were considered to represent true bacteremia. The most frequently identified microorganism was Streptococcus pneumoniae (29.2%), with a decrease in the number of cases between 2008 and 2015. Staphylococcus aureus was the second most common organism (19.2%) being 21.7% of these methicillin-resistant. Escherichia coli was the most common isolate in children aged less than three months.

CONCLUSION

We found a rate of true bacteremia in children similar to recent studies. Although Streptococcus pneumoniae remains the most common microorganism, its prevalence may be declining. Monitoring microbiological data in children has implications in practice, particularly in local antibiotic prescription.

Secondary Immunodeficiency and Hypogammaglobulinemia with IgG Levels of <5 g/L in Patients with Multiple Myeloma: A Retrospective Study Between 2012 and 2020 at a University Hospital in China

Background

Infections are the main cause of mortality and morbidity in multiple myeloma (MM) patients. However, adult immunodeficiency specialists in China are lacking, and the care of secondary immunodeficiency (SID) and the prognostic role of hypogammaglobulinemia in MM is unknown.

Material/Methods

MM patients (295) were retrospectively analyzed between January 2012 and 2020 in Zhejiang Provincial People’s Hospital, Hangzhou Medical College. MM patients with immunoglobulin (Ig) G <5 g/L were defined as SID patients. The care of these patients and the prognostic role of IgG <5 g/L were analyzed.

Results

Forty-five of 295 MM patients with IgG <5 g/L were defined as SID patients. These 45 patients mainly had recurrent infections, especially pulmonary bacterial infections; 2 patients had them 5 times/year. The median survival time was significantly shorter in MM patients with SID (24 vs 66 months). More importantly, the multivariate and univariate analysis revealed that IgG <5 g/L was an independent prognostic factor for MM patients.

Conclusions

Ig replacement therapy or prophylactic antibiotics for MM patients with SID were lacking in this single retrospective study. IgG <5 g/L could be a prognostic marker for MM patients.

The burden of Arcanobacterium haemolyticum pharyngitis: A systematic review and management algorithm

INTRODUCTION

Arcanobacterium haemolyticum causes pharyngotonsillitis in children and young adults. It is rarely isolated in pharyngeal swabs as testing for it is not routine. Data on complications, management, and antibiotic susceptibility testing is limited. We sought to review the available literature on the presentation and management of A. haemolyticum pharyngotonsillitis in this age group.

METHODS

A systematic review of eligible studies reporting pharyngotonsillitis and related complications in children and young adults caused by A. haemolyticum was conducted. Literature from case reports, case series, and available cohorts was compiled. Data were analyzed using descriptive statistics.

RESULTS

The initial database search yielded 63 articles, after applying exclusion criteria 17 studies were included. 191 patients were identified with a median age of 16.5 years. The most common presentation was throat pain reported in 93.7% of patients. Tonsillar exudates, fever at presentation and rash were present in more than half of the reviewed cases. The diagnosis was established by a positive culture on a pharyngeal swab in 98.8% of swabs collected. Complications described included peritonsillar abscesses, Lemierre's syndrome, pneumonia, and sepsis. Penicillin was the first line antibiotic in 81% of patients followed by macrolides in 19 patients (18%).

CONCLUSIONS

A. haemolyticum occurs in children and young adults and may result in complications. Our review supports its susceptibility to penicillin. We suggest a diagnostic and management algorithm to guide clinicians in targeted testing and aid with decision making regarding timely and appropriate antibiotic therapy, in an effort to reduce the burden of its complications.

Real-time Polymerase Chain Reaction for Mycobacterium tuberculosis Meningitis is More Sensitive in Patients with HIV Co-Infection

BACKGROUND

Tuberculous meningitis (TbM) is the most severe complication of extra pulmonary tuberculosis (Tb). There is a higher frequency of positive cerebrospinal fluid (CSF) cultures for Mycobacterium tuberculosis (MTb) in samples from human immunodeficiency virus (HIV) co-infected patients than in those from HIV-negative patients. We hypothesized that real time PCR assays for MTb (MTb qPCR) using CSF would be more sensitive in HIV co-infected patients owing to a greater MTb burden. The present study aimed to verify the diagnostic performance of MTb qPCR in CSF of TbM patients who either were co-infected with HIV or were HIVnegative.

METHODS

A total of 334 consecutive participants with suspected TbM were divided into two groups: HIV co-infected and HIV-negative; each group was categorized into definite TbM, probable TbM, possible TbM, and TbM-negative subgroups based on clinical, laboratory and imaging data. We evaluated the diagnostic characteristics of MTb qPCR analysis to detect TbM in CSF by comparing the results to those obtained for definite TbM (i.e., positive MTb culture) and/or probable TbM in CSF, as gold standard.

RESULTS

The sensitivity of MTb qPCR in the definite and probable subgroups of the HIV coinfected participants (n = 14) was 35.7%, with a specificity of 93.8%, negative predictive value (NPV) of 94.4%, and negative clinical utility index (CUI-) of 0.89. Results of the HIV-negative group (n = 7) showed lower sensitivity (14.3%) and similar specificity, NPV, and CUI-.

CONCLUSION

The findings confirmed our hypothesis, despite the low sensitivity. MTb qPCR may significantly contribute to diagnosis when associated with clinical criteria and complementary examinations.

Distinguishing septic shock from non-septic shock in postsurgical patients using gene expression

OBJECTIVES

To obtain a gene expression signature to distinguish between septic shock and non-septic shock in postoperative patients, since patients with both conditions show similar signs and symptoms.

METHODS

Differentially expressed genes were selected by microarray analysis in the discovery cohort. These genes were evaluated by quantitative real time polymerase chain reactions in the validation cohort to determine their reliability and predictive capacity by receiver operating characteristic curve analysis.

RESULTS

Differentially expressed genes selected were IGHG1, IL1R2, LCN2, LTF, MMP8, and OLFM4. The multivariate regression model for gene expression presented an area under the curve value of 0.922. These genes were able to discern between both shock conditions better than other biomarkers used for diagnosis of these conditions, such as procalcitonin (0.589), C-reactive protein (0.705), or neutrophils (0.605).

CONCLUSIONS

Gene expression patterns provided a robust tool to distinguish septic shock from non-septic shock postsurgical patients and shows the potential to provide an immediate and specific treatment, avoiding the unnecessary use of broad-spectrum antibiotics and the development of antimicrobial resistance, secondary infections and increase health care costs.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

The selection of indicators from initial blood routine test results to improve the accuracy of early prediction of COVID-19 severity

The global pandemic of COVID-19 poses a huge threat to the health and lives of people all over the world, and brings unprecedented pressure to the medical system. We need to establish a practical method to improve the efficiency of treatment and optimize the allocation of medical resources. Due to the influx of a large number of patients into the hospital and the running of medical resources, blood routine test became the only possible check while COVID-19 patients first go to a fever clinic in a community hospital. This study aims to establish an efficient method to identify key indicators from initial blood routine test results for COVID-19 severity prediction. We determined that age is a key indicator for severity predicting of COVID-19, with an accuracy of 0.77 and an AUC of 0.92. In order to improve the accuracy of prediction, we proposed a Multi Criteria Decision Making (MCDM) algorithm, which combines the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Naïve Bayes (NB) classifier, to further select effective indicators from patients' initial blood test results. The MCDM algorithm selected 3 dominant feature subsets: {Age, WBC, LYMC, NEUT} with a selection rate of 44%, {Age, NEUT, LYMC} with a selection rate of 38%, and {Age, WBC, LYMC} with a selection rate of 9%. Using these feature subsets, the optimized prediction model could achieve an accuracy of 0.82 and an AUC of 0.93. These results indicated that Age, WBC, LYMC, NEUT were the key factors for COVID-19 severity prediction. Using age and the indicators selected by the MCDM algorithm from initial blood routine test results can effectively predict the severity of COVID-19. Our research could not only help medical workers identify patients with severe COVID-19 at an early stage, but also help doctors understand the pathogenesis of COVID-19 through key indicators.

Evaluation of a Novel CLIA Monotest Assay for the Detection of Anti-Hepatitis E Virus-IgG and IgM: A Retrospective Comparison with a Line Blot and an ELISA

Despite the increasing relevance of Hepatitis E, an emerging disease endemic in developing and with increasing numbers of sporadic cases in industrialized countries, commercial tests are mainly based on batch oriented serological assays. In this retrospective study, we compared a line immunoassay (LIA; recomLine HEV, Mikrogen) and an ELISA (EIA; Anti-Hepatitis E Virus ELISA, Euroimmun) with a novel chemoluminescence immunoassay in a monotest format (CLIA; Hepatitis E VirClia, Vircell). Twenty sera of PCR proven cases of hepatitis E and 68 blood samples serologically pre-characterized were included. Applying the WHO reference standard, the CLIA demonstrated the highest analytical sensitivity for IgG and IgM. The combinations of CLIA/EIA (IgG and IgM) and CLIA/LIA (IgG) measurements showed substantial correlation. Compared to overall antibody detection (seropositivity in ≥2 assays), CLIA correlation was excellent, outperforming LIA (IgM) and EIA (IgG and IgM). Minor IgM cross reactivity in samples of patients with acute EBV infection was observed in all three assays. The CLIA showed good performance in diagnostic samples compared to established LIA and EIA assays. Due to its ready-to-use monotest format, the CLIA allows simple, time- and cost-effective handling of single samples. These qualities make the assay suitable for diagnostics, especially in the emergency setting and for low-throughput laboratories.

The investigation of bacterial adhesion of palatine tonsils epithelial cells in patient with infectious mononucleosis

Aim. To evaluate the features of pharynx tonsils mucous membrane colonization by pathogenic and opportunistic microorganisms by using the pharynx palatine tonsils epithelium electron microscopic examination of the patients with infectious mononucleosis and acute streptococcal tonsillitis. Materials and methods. Two patients – patient P., 12 years old with a confirmed diagnosis of infectious mononucleosis and patient A., 8 years old with confirmed acute streptococcal tonsillitis. The patients were taken a bacteriological examination of the mucus and epithelium scraping from the surface of the pharyngeal tonsils. Tissue samples were examined in the electron microscopy laboratory of the Lviv National University. Results and discussion. 36 tonsils epithelial tissue micro preparations of patient A. and 41 micro preparations of patient P. were studied. Streptococcus pyogenes, Str. pneumoniae, Str. viridans, Сandida albicans, as well as non-pathogenic bacteria: Diphtheroides sp., Neisseria sp., Corynebacterium spp. were identified as result of the patient P. bacteriological examination of mucus from the surface of the pharyngeal tonsils. Staph. aureus, Str. viridans, Str. pneumoniae were identified during a bacteriological examination of patient A. Eosinophils with a two-segmented nucleus, specific granularity, phagocytosed spherical bacteria in the cytoplasm were detected during the histological examination of the materials taken from the surface of the patient’s tonsils with acute tonsillitis. Research showed that bacteria were accumulated not only in the structure of extracellular detritus. Numerous bacteria accumulations were also found in the cytoplasm of the epithelial cells in the patient with infectious mononucleosis. The cell's shape looked like a bunch of grapes. Conclusions. The electron microscopic examination showed differences in the coccal flora localization: the extracellular localization of bacteria in the patient with acute bacterial tonsillitis and intraepithelial presence of the bacteria in the patient with tonsillitis during infectious mononucleosis were found.

Future Biomarkers for Infection and Inflammation in Febrile Children

Febrile patients, suffering from an infection, inflammatory disease or autoimmunity may present with similar or overlapping clinical symptoms, which makes early diagnosis difficult. Therefore, biomarkers are needed to help physicians form a correct diagnosis and initiate the right treatment to improve patient outcomes following first presentation or admittance to hospital. Here, we review the landscape of novel biomarkers and approaches of biomarker discovery. We first discuss the use of current plasma parameters and whole blood biomarkers, including results obtained by RNA profiling and mass spectrometry, to discriminate between bacterial and viral infections. Next we expand upon the use of biomarkers to distinguish between infectious and non-infectious disease. Finally, we discuss the strengths as well as the potential pitfalls of current developments. We conclude that the use of combination tests, using either protein markers or transcriptomic analysis, have advanced considerably and should be further explored to improve current diagnostics regarding febrile infections and inflammation. If proven effective when combined, these biomarker signatures will greatly accelerate early and tailored treatment decisions.

Educational Case: Staphylococcus aureus Bacteremia: Utilization of Rapid Diagnostics for Bloodstream Pathogen Identification and Prediction of Antimicrobial Susceptibility

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040. ¹

Diagnostic Tests for COVID-19

The diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has ramifications on both an individual level and a public health level. The use of appropriate testing mechanisms is paramount to preventing transmission, along with offering treatment to those who are infected and show appropriate symptomatology. The choice of employing a specific test often relies on laboratory capabilities, including the abilities of the medical technologists, the cost of testing platforms, and the individual quirks of each test. This chapter intends to discuss the relevant issues relating to diagnostic testing for SARS-CoV-2, including specimen types and collection methods, viral detection methods, and serological testing.

Understanding the most commonly billed diagnoses in primary care: Acute pharyngitis

ABSTRACT

This is a 12-part series on the most commonly billed diagnoses in primary care. The article discusses the pathophysiologic processes of acute pharyngitis as well as the clinical manifestations and treatments and how they are linked to disease pathogenesis.

A Case of Testicular Granulomatous Inflammation Mistaken for Malignancy: Tuberculosis Identified Post Orchiectomy

We describe the case of a 41-year-old Hispanic male, inconsistently adherent to visits and workup due to socioeconomic challenges, who presented with a right testicular mass. Because of the overriding concern that this was malignant, he underwent a right orchiectomy. Pathology revealed granulomatous disease with no evidence of malignancy. No specific diagnosis was made histologically or microbiologically on primary laboratory investigation. Six months later, he developed swelling of the left testicle and was subsequently seen in consultation at the Infectious Disease Clinic Kern Medical. An extensive evaluation for granulomatous inflammation was undertaken without a positive result. A clinical diagnosis of tuberculous epididymal orchitis was made and the patient was initiated on standard 4-drug antituberculous therapy. There was a gradual resolution of pain and swelling. After 6 months of therapy, there was no evidence of residual disease. The patient remains asymptomatic after 8 months of post-therapy follow-up.

Carriage of two carbapenem-resistance genes in Pseudomonas aeruginosa isolated from hospital-acquired infections in children from Costa Rica: the importance of local epidemiology

Background

The assessment of Hospital-acquired infections due to multidrug-resistant bacteria involves the use of a variety of commercial and laboratory-developed tests to detect antimicrobial resistance genes in bacterial pathogens; however, few are evaluated for use in low- and middle-income countries.

Methods

We used whole-genome sequencing, rapid commercial molecular tests, laboratory-developed tests and routine culture testing.

Results

We identified the carriage of the metallo-β-lactamase bla_VIM-2 and bla_IMP-18 alleles in Carbapenem-Resistant Pseudomonas aeruginosa infections among children in Costa Rica.

Conclusions

The bla_IMP-18 allele is not present in the most frequently used commercial tests; thus, it is possible that the circulation of this resistance gene may be underdiagnosed in Costa Rica.

Infections in Older Adults

Infections in elderly patients can prove diagnostically challenging. Age-related factors affecting the immune system in older individuals contribute to nonspecific presentations. Other age-related factors and chronic conditions have symptoms that may or may not point to an infectious diagnosis. Delay in administration of antimicrobials can lead to poor outcomes; however, unnecessary administration of antimicrobials can lead to increased morbidity and contribute to the emergence of multidrug-resistant organisms. Careful clinical assessment and consideration of patient history and risk factors is crucial. When necessary, antimicrobials should be chosen that are appropriate for the diagnosis and deescalated as soon as possible.

Prevalence and Predictors of Bacterial Contamination in Excisional Lymph Node Biopsies: Implications for Diagnosis and Management

Routine tissue handling exposes lymph node specimens to microbial contamination that can confound microbiological culture results and interfere with diagnosis. The scope and impact of this problem remain poorly understood. We combined over 13 years of lymph node pathology, culture data, and patient records to define the prevalence, predisposing factors, microbiology, and clinical management of false-positive lymph node cultures at a large academic medical center. Nearly one third (31.9%) of 216 cultured lymph nodes yielded bacterial growth. Approximately 90% of positive bacterial cultures grew 1 of 2 common skin-resident taxa-coagulase-negative Staphylococcus and Cutibacterium acnes-with well-documented predispositions for contamination in other clinical settings. Lymph nodes excised from axillary, cervical, and inguinal regions yielded higher positive culture rates than nodes excised from the mediastinum, suggesting proximity to the skin surface may increase contamination risk. Accordingly, cultures from thoracoscopic pulmonary resections displayed contamination rates over 5-fold lower than those from percutaneously accessed lymph nodes. Lymph nodal tissue allocated for culture in the operating room yielded unexpectedly high contamination rates, significantly higher than cultures sent from the frozen section processing area. A significant minority of contamination events were noted in the clinical record and prompted antibiotic therapy on multiple occasions. Collectively, our results illuminate the risk factors contributing to bacterial contamination and argue that routine lymph node bacterial cultures provide minimal clinical benefit for adult patients. This widespread bacterial contamination also warrants cautious implementation of increasingly sensitive molecular microbiology tools for excised tissues.

Atypical case of syphilitic hepatitis

A 31-year-old immunocompetent, heterosexual man with no relevant medical history presented with 1 week of jaundice, abdominal pain, cough and headache. Examination revealed scleral icterus, right upper quadrant tenderness and hepatomegaly. Initial investigations revealed hyperbilirubinaemia and elevated transaminases. Serum studies were positive for antinuclear antibodies, antimitochondrial antibodies, and herpes simplex virus IgM. Despite being started on intravenous acyclovir, his bilirubin and transaminase levels continued to rise. He was subsequently tested for syphilis given his maculopapular rash on the soles of his feet and it returned positive. He improved clinically with the initiation of penicillin. In this case, we will discuss the presentation, diagnosis and treatment of syphilitic hepatitis.

Genitourinary Emergencies in Older Adults

Older adults are frequently seen in the emergency department for genitourinary complaints, necessitating that emergency physicians are adept at managing a myriad of genitourinary emergencies. Geriatric patients may present with acute kidney injury, hematuria, or a urinary infection and aspects of how managing these presentations differs from their younger counterparts is emphasized. Older adults may also present with acute urinary retention or urinary incontinence as a result of genitourinary pathology or other systemic etiologies. Finally, genital complaints as they pertain to older adults are briefly highlighted with emphasis on emergent management and appropriate referrals.

Management of Staphylococcus aureus Bloodstream Infections

Staphylococcus aureus bloodstream infections are associated with a high morbidity and mortality. Nevertheless, significance of a positive blood culture with this pathogen is often underestimated or findings are misinterpreted as contamination, which can result in inadequate diagnostic and therapeutic consequences. We here review and discuss current diagnostic and therapeutic key elements and open questions for the management of Staphylococcus aureus bloodstream infections.

Common bacterial causes of external ocular infections, associated risk factors and antibiotic resistance among patients at ophthalmology unit of Felege Hiwot Referral Hospital, Northwest Ethiopia: a cross-sectional study

BACKGROUND

Ocular infections are a serious public health problem in Ethiopia with increased incidence of morbidity and blindness. Empirical therapy with topical ophthalmic broad spectrum antibiotic formulations is also a prevailing practice. The aim of this study was to determine the bacterial causes of external ocular infections (EOIs), antimicrobial resistance and its associated risk factors among patients at Felege Hiwot Referral Hospital, Northwest Ethiopia.

METHODS

A hospital based cross - sectional study was conducted from 1 February to 30 April 2019. Patients with EOIs were consecutively included from 1 February to 30 April, 2019. Data were collected using structured questionnaire by face-to-face interview and complemented with patient card review. Conjunctival, eyelid margin and lacrimal sac swabs were collected aseptically. Bacterial species were identified using standard bacteriological techniques. Antimicrobial susceptibility testing was done using Kirby-Bauer disk diffusion method. Binary logistic regression analysis was calculated to identify the factors associated with EOIs. P.value (p) < < 0.05 was considered as statistically significant.

RESULTS

A total of 360 patients took part in the study and majority of them were males (64.7%). The median age of study participants was 59.5 years. Overall, 208(57.8%) (95%CI = 52.6- - 62.8%) of patients had culture confirmed bacterial EOIs. The proportion of culture confirmed EOIs was 60.4% among conjunctivitis cases and 55.8% among blepharitis. Ocular trauma (P < < 0.001), ocular disease (P < < 0.001) and having eye allergy (P = 0.027) were significantly associated with EOIs. The most frequent isolates were S. aureus (37%), K. pneumoniae (13.5%), Proteus(7.2%) spp., S. pneumoniae (4.3%), Citrobacter spp. (3.4%) and P. aeruginosa (2.9%). Gram positive isolates were resistant to penicillin in 87% and ampicillin in 86.2%. Gram negative isolates were resistant to ampicillin (87.5%). P.aeruginosa isolates (85.3%) were resistant to piperacillin and 50% were resistant to tobramycin. Overall, 45.2% of the isolates were multi-drug resistant. The percentage of multi-drug resistance was 80% among Enterobacter isolates and 64.3% among K. pneumoniae.

CONCLUSIONS

Bacterial external ocular infections linked with multi-drug resistance and resistance to penicillin, ampicillin, tetracycline and piperacillin are high. Therefore, empirical treatment of eye infections in the study area needs to be monitored by regular antimicrobial-susceptibility testing of isolates.

A contemporary review of Clostridioides difficile infections in patients with haematologic diseases

Clostridioides (Clostridium) difficile (C. difficile) infection is one of the most common causes of increased morbidity and mortality. Approximately 500 000 C. difficile infections (CDIs) occur each year in the United States, and they result in more than 29 000 deaths. Patients with haematologic diseases are at a higher risk for this infection due to frequent hospitalization and exposure to treatment-associated risk factors. Whilst several currently available antimicrobial agents offer resolution, recurrence of infection remains a major concern. Recent advancement in deciphering C. difficile virulence mechanisms and identification of its allies in contributing to the infection has led to the development of alternative treatment strategies. Here, we will provide a contemporary discussion of how major risk factors in haematologic diseases, such as immunosuppression, chemoradiation, use of antibiotic, proton pump inhibitor and opioid, and deficiency in butyrate and antimicrobial peptides contribute to C. difficile infection. Next, we will highlight different approaches to control and mitigate this infection such as antibiotic stewardship and faecal microbiota transplantation. Finally, we will explore several emerging treatments such as use of pre- and probiotics, immunotherapy and microbiome-sparing agents.

Radiological, epidemiological and clinical patterns of pulmonary viral infections

Respiratory viruses are the most common causes of acute respiratory infections. However, identification of the underlying viral pathogen may not always be easy. Clinical presentations of respiratory viral infections usually overlap and may mimic those of diseases caused by bacteria. However, certain imaging morphologic patterns may suggest a particular viral pathogen as the cause of the infection. Although definitive diagnosis cannot be made on the basis of clinical or imaging features alone, the use of a combination of clinical and radiographic findings can substantially improve the accuracy of diagnosis. The purpose of this review is to present the clinical, epidemiological and radiological patterns of lower respiratory tract viral pathogens providing a comprehensive approach for their diagnosis and identification in hospitals and community outbreaks.

Current Concepts in Pediatric Septic Arthritis

Septic arthritis continues to present challenges regarding the clinical diagnosis, workup, and definitive management. Urgent management is essential, so treating surgeons must efficiently work through differential diagnoses, identify concomitant infections, and do a timely irrigation and débridement. The incidence of methicillin-resistant Staphylococcus aureus is increasing, typically resulting in a more rapid progression of symptoms with more severe clinical presentation. The diagnostic utility of MRI has resulted in improved detection of concomitant septic arthritis and osteomyelitis, although MRI must not substantially delay definitive management. Early diagnosis followed by urgent irrigation and débridement and antibiotic therapy are essential for satisfactory long-term outcomes. Antibiotics should not be administered until blood cultures and arthrocentesis fluid are obtained, except in rare cases of a septic or toxic patient. Once cultures are obtained, empiric antibiotic therapy should commence and provide coverage for the most likely pathogens, given the patient's age. Laboratory markers, especially C-reactive protein, should be followed until normalization and correlate with resolution of clinical symptoms. Definitive antibiotic selection should be shared with a pediatric infectious disease specialist, who can help guide the duration of treatment.