Diffusion-weighted MRI abnormalities in an outbreak of Streptococcus agalactiae Serotype III, multilocus sequence type 283 meningitis

Reassessment of Pediatric Tension-Type Headaches

A retrospective multicenter chart review was conducted with the objective of evaluating the hypothesis that certain cases diagnosed as tension-type headache (TTH) in pediatric neurology are not stress-related or central sensitization-related conditions but may mimic an autoimmune disorder of the dura mater. Of the 29,642 patient charts reviewed, 12,424 charts (42%) were excluded because of incomplete data and 17,218 cases were analyzed. For all the 29,642 charts, TTH or chronic daily headaches were diagnosed in 29.2% of cases. Among the 17,218 cases subjected to detailed diagnostic procedures, TTH was diagnosed in only 5%. In 7,044 cases, the initial diagnosis of TTH was changed to headache attributed to infection (87.4%), which was supported by the presence of meningeal signs, high antistreptolysin-O titers, and, in 46% of cases, magnetic resonance imaging (MRI)-detected thickening of the cranial dura mater. The initial diagnosis of migraine was confirmed in 87.7% of cases (8,034/9,162). In some cases of treatment-resistant pediatric recurrent headaches, which are initially diagnosed as TTH, a secondary type of headache may be suspected as the underlying cause. Usually this type of headache has streptococcal infection-related laboratory findings, the meninges as the site of the lesion, and meningism as the clinical presentation.

Disentangling etiologies of CNS infections in Singapore using multiple correspondence analysis and random forest

Central nervous system (CNS) infections cause substantial morbidity and mortality worldwide, with mounting concern about new and emerging neurologic infections. Stratifying etiologies based on initial clinical and laboratory data would facilitate etiology-based treatment rather than relying on empirical treatment. Here, we report the epidemiology and clinical outcomes of patients with CNS infections from a prospective surveillance study that took place between 2013 and 2016 in Singapore. Using multiple correspondence analysis and random forest, we analyzed the link between clinical presentation, laboratory results, outcome and etiology. Of 199 patients, etiology was identified as infectious in 110 (55.3%, 95%-CI 48.3–62.0), immune-mediated in 10 (5.0%, 95%-CI 2.8–9.0), and unknown in 79 patients (39.7%, 95%-CI 33.2–46.6). The initial presenting clinical features were associated with the prognosis at 2 weeks, while laboratory-related parameters were related to the etiology of CNS disease. The parameters measured were helpful to stratify etiologies in broad categories, but were not able to discriminate completely between all the etiologies. Our results suggest that while prognosis of CNS is clearly related to the initial clinical presentation, pinpointing etiology remains challenging. Bio-computational methods which identify patterns in complex datasets may help to supplement CNS infection diagnostic and prognostic decisions.

Neuroimaging in Zoonotic Outbreaks Affecting the Central Nervous System: Are We Fighting the Last War?

When preparing for the coronavirus disease 2019 pandemic and its effects on the CNS, radiologists should be familiar with neuroimaging appearances in past zoonotic infectious disease outbreaks. Organisms that have crossed the species barrier from animals to humans include viruses such as Hendra, Nipah, Severe Acute Respiratory Syndrome, and influenza, as well as bacteria and others. Brain CT and MR imaging findings have included cortical abnormalities, microinfarction in the white matter, large-vessel occlusion, and features of meningitis. In particular, the high sensitivity of diffusion-weighted MR imaging in detecting intracranial abnormalities has been helpful in outbreaks. Although the coronaviruses causing the previous Severe Acute Respiratory Syndrome outbreak and the current coronavirus disease 19 pandemic are related, it is important to be aware of their similarities as well as potential differences. This review describes the neuroimaging appearances of selected zoonotic outbreaks so that neuroradiologists can better understand the current pandemic and potential future outbreaks.

A comparison of Streptococcus agalactiae septic arthritis and non-Streptococcus agalactiae septic arthritis

INTRODUCTION

Streptococcus agalactiae (Group B Streptococcus, GBS) is an uncommon cause of septic arthritis in the adult population. In recent years, there has been an increase in the incidence of GBS septic arthritis. This study aims to compare the clinical presentation, investigations, microbiology and outcome of management in patients with GBS and non-GBS septic arthritis.

METHODS

Retrospective review of hospital surgical records was done to identify all patients treated surgically at our institution from January 2011 to January 2016 for primary septic arthritis. Patients were categorised into two groups: those with culture-proven GBS septic arthritis and those with causative pathogens that were not GBS. Patients who were medically unfit for surgical intervention as well as those who declined interventional procedures were excluded from the study.

RESULTS

A total of 83 patients were included in the study: 62 (74.7%) had non-GBS septic arthritis and 21 (25.3%) had GBS septic arthritis. Patients with GBS septic arthritis were more likely to have polyarticular involvement (p < 0.001) and involvement of less common sites such as the elbow joint. They were also more likely to have elevated inflammatory markers (C-reactive protein > 150 mg/L; p = 0.017) and positive blood cultures (p = 0.02), and were typically healthy adults with no medical comorbidities (p = 0.012).

CONCLUSION

Patients with GBS septic arthritis were more likely to present with polyarticular involvement, positive blood cultures and higher levels of C-reactive protein on admission, and tended to be healthier individuals with no medical comorbidities.

Survival of an emerging foodborne pathogen: Group B Streptococcus (GBS) serotype III sequence type (ST) 283-under simulated partial cooking and gastric fluid conditions

Group B Streptococcus (GBS) was previously not known to be transmitted through food, but an outbreak investigation in Singapore in 2015 documented for the first time an association between GBS Type III Sequence Type 283 infection and consumption of raw fish dishes. As very little is known about the survival of GBS during heat treatment and the stomach transit, its survival under simulated conditions was studied, in comparison with that of Escherichia coli O157:H7 and Listeria monocytogenes. The mean D-values of four GBS strains ranging from 0.72 to 0.88 min in neutral pH tryptone soy broth at 56.4 °C and 0.44-1.43 min at pH 2.35 at 37 °C in simulated gastric fluid, were significantly lower (p < 0.05) than those of E. coli O157:H7 and L. monocytogenes. This study suggests possible factors other than acid or heat resistance of GBS to be instrumental to its pathogenicity.

Capsular Switching and ICE Transformation Occurred in Human Streptococcus agalactiae ST19 With High Pathogenicity to Fish

Although Streptococcus agalactiae (GBS) cross-infection between human and fish has been confirmed in experimental and clinical studies, the mechanisms underlying GBS cross-species infection remain largely unclear. We have found different human GBS ST19 strains exhibiting strong or weak pathogenic to fish (sGBS and wGBS). In this study, our objective was to identify the genetic elements responsible for GBS cross species infection based on genome sequence data and comparative genomics. The genomes of 11 sGBS strains and 11 wGBS strains were sequenced, and the genomic analysis was performed base on pan-genome, CRISPRs, phylogenetic reconstruction and genome comparison. The results from the pan-genome, CRISPRs analysis and phylogenetic reconstruction indicated that genomes between sGBS were more conservative than that of wGBS. The genomic differences between sGBS and wGBS were primarily in the Cps region (about 111 kb) and its adjacent ICE region (about 106 kb). The Cps region included the entire cps operon, and all sGBS were capsular polysaccharide (CPS) type V, while all wGBS were CPS type III. The ICE region of sGBS contained integrative and conjugative elements (ICE) with IQ element and erm(TR), and was very conserved, whereas the ICE region of wGBS contained ICE with mega elements and the variation was large. The capsular switching (III–V) and transformation of ICE adjacent to the Cps region occurred in human GBS ST19 with different pathogenicity to fish, which may be related to the capability of GBS cross-infection.

Group B Streptococcus Infections Caused by Improper Sourcing and Handling of Fish for Raw Consumption, Singapore, 2015-2016

Policies and guidelines regarding sale of ready-to-eat raw fish dishes have been updated.

We assessed microbial safety and quality of raw fish sold in Singapore during 2015–2016 to complement epidemiologic findings for an outbreak of infection with group B Streptococcus serotype III sequence type (ST) 283 associated with raw fish consumption. Fish-associated group B Streptococcus ST283 strains included strains nearly identical (0–2 single-nucleotide polymorphisms) with the human outbreak strain, as well as strains in another distinct ST283 clade (57–71 single-nucleotide polymorphisms). Our investigations highlight the risk for contamination of freshwater fish (which are handled and distributed separately from saltwater fish sold as sashimi) and the need for improved hygienic handling of all fish for raw consumption. These results have led to updated policy and guidelines regarding the sale of ready-to-eat raw fish dishes in Singapore.

A Case Report: Organs From a Donor With Highly Virulent Zoonotic Outbreak Strain of Streptococcus agalactiae Serotype III, Multilocus Sequence Type 283 Infective Endocarditis Did Not Result in Transmission With Adequate Prophylactic Antibiotic Cover

In 2015, an outbreak involving a highly virulent zoonotic outbreak strain of Streptococcus agalactiae serotype III, multilocus sequence type 283 occurred in Singapore with increased neurologic complications, septic arthritis, and spinal infections in healthier patients. We report a case of a successful dual kidney transplant from a deceased donor with infective endocarditis and disseminated infection with the same strain of S agalactiae and we review the current literature.

Group B Streptococcal Prosthetic Knee Joint Infection Linked to the Consumption of Raw Fish

Introduction

Group B Streptococcal (GBS) prosthetic joint infections (PJI) are rare, accounting for only 4.6-6% of primary and revision total knee replacements (TKRs). In 2015, there was an outbreak of GBS infections in Singapore with an association confirmed between consumption of Chinese-style raw fish dishes (snakehead fish, Asian bighead carp) and GBS infection, Type III GBS ST283 strain, affecting more than 200 patients in Singapore. This outbreak is the largest of its kind in the world and also the first time that foodborne transmission of GBS has been proven. We present the first reported case in the literature of a confirmed PJI in a TKR related to foodborne transmission of GBS through consumption of raw fish (Snakehead fish).

Case Report

Our patient is a 66-year-old Chinese female admitted with a 24-h history of acute right knee pain and swelling with associated fever in the context of consuming raw fish porridge 3 days before the onset of her symptoms. She had a TKR performed in the same knee 7 years before this presentation. Her GBS PJI was confirmed on both blood and intraoperative tissue/fluid cultures during the outbreak of GBS infections in Singapore. This was managed with debridement, polyethylene liner change, retention of metal prosthesis, and culture-directed antibiotics with good outcomes.

Conclusion

Snakehead fish is a popular dish in the Asian community as a traditional remedy to promote wound healing after surgery. Our paper highlights the link between raw fish consumption and invasive GBS causing PJIs. This can occur in healthy adults, even in the absence of gastrointestinal symptoms, despite being a foodborne transmission. Our paper also highlights that GBS PJIs can be managed with debridement, antibiotic therapy, and implant retention with good outcomes in the setting of acute hematogenous infection. We recommend the inclusion of raw fish consumption on history taking in the workup of suspected PJIs and counseling patients preoperatively on the risk of GBS PJIs with the consumption of raw fish dishes (snakehead fish and Asian bighead carp) to mitigate unnecessary PJI risk.

Pathogenicity of Human ST23 Streptococcus agalactiae to Fish and Genomic Comparison of Pathogenic and Non-pathogenic Isolates

Streptococcus agalactiae, or Group B Streptococcus (GBS), is a major pathogen causing neonatal sepsis and meningitis, bovine mastitis, and fish meningoencephalitis. CC23, including its namesake ST23, is not only the predominant GBS strain derived from human and cattle, but also can infect a variety of homeothermic and poikilothermic species. However, it has never been characterized in fish. This study aimed to determine the pathogenicity of ST23 GBS to fish and explore the mechanisms causing the difference in the pathogenicity of ST23 GBS based on the genome analysis. Infection of tilapia with 10 human-derived ST23 GBS isolates caused tissue damage and the distribution of pathogens within tissues. The mortality rate of infection was ranged from 76 to 100%, and it was shown that the mortality rate caused by only three human isolates had statistically significant difference compared with fish-derived ST7 strain (P < 0.05), whereas the mortality caused by other seven human isolates did not show significant difference compared with fish-derived ST7 strain. The genome comparison and prophage analysis showed that the major genome difference between virulent and non-virulent ST23 GBS was attributed to the different prophage sequences. The prophage in the P1 region contained about 43% GC and encoded 28–39 proteins, which can mediate the acquisition of YafQ/DinJ structure for GBS by phage recombination. YafQ/DinJ belongs to one of the bacterial toxin–antitoxin (TA) systems and allows cells to cope with stress. The ST23 GBS strains carrying this prophage were not pathogenic to tilapia, but the strains without the prophage or carrying the pophage that had gene mutation or deletion, especially the deletion of YafQ/DinJ structure, were highly pathogenic to tilapia. In conclusion, human ST23 GBS is highly pathogenic to fish, which may be related to the phage recombination.