- Volume 3, Issue 7, 2021

Methane emissions from enteric fermentation in the ruminant digestive system generated by methanogenic archaea are a significant contributor to anthropogenic greenhouse gas emissions. Additionally, methane produced as an end-product of enteric fermentation is an energy loss from digested feed. To control the methane emissions from ruminants, extensive research in the last decades has been focused on developing viable enteric methane mitigation practices, particularly, using methanogen-specific inhibitors. We report here the utilization of two known inhibitors of methanogenic archaea, neomycin and chloroform, together with a recently identified inhibitor, echinomycin, to produce resistant mutants of Methanococcus maripaludis S2 and S0001. Whole-genome sequencing at high coverage (> 100-fold) was performed subsequently to investigate the potential targets of these inhibitors at the genomic level. Upon analysis of the whole-genome sequencing data, we identified mutations in a number of genetic loci pointing to potential mechanisms of inhibitor action and their underlying mechanisms of resistance.

Family clusters have contributed significantly to the onward spread of SARS-CoV-2. However, the dynamics of viral transmission in this setting remain incompletely understood. We describe the clinical and viral-phylogenetic characteristics of a family cluster of SARS-CoV-2 infections with a high attack rate, and explore how whole-genome sequencing (WGS) can inform outbreak investigations in this context. In this cluster, the first symptomatic case was a 22-month-old infant who developed rhinorrhoea and sneezing 2 days prior to attending a family gathering. Subsequently, seven family members in attendance at this event were diagnosed with SARS-CoV-2 infections, including the infant described. WGS revealed indistinguishable SARS-CoV-2 genomes recovered from the adults at the gathering, which were closely related genetically to B.1 lineage viruses circulating in the local community. However, a divergent viral sub-lineage was recovered from the infant and another child, each harbouring a distinguishing spike substitution (N30S). This suggested that the infant was unlikely to be the primary case, despite displaying symptoms first, and additional analysis of her nasopharyngeal swab revealed a picornavirus co-infection to account for her early symptoms. Our findings demonstrate how WGS can elucidate the transmission dynamics of SARS-CoV-2 infections within household clusters and provide useful information to support outbreak investigations. Additionally, our description of SARS-CoV-2 viral lineages and notable variants circulating in Ireland to date provides an important genomic-epidemiological baseline in the context of vaccine introduction.

Corynebacterium freneyi is a recently described coryneform bacteria. It is only rarely identified from clinical specimens and its pathogenic significance has not been well studied. Here we report the isolation of the species from the throat swab of a patient with suspected diphtheria. The morphology on direct microscopy and culture also closely resembled Corynebacterium diphtheriae , which almost led to misidentification. The prompt clinical and microbiological response suggests a probable pathogenic role. This is the first report of the isolation of this species from an oropharyngeal sample.

Spondylodiscitis is an infectious inflammation that affects the intervertebral disc and adjacent structures. Treating infective spondylodiscitis is often challenging due to the lack of specific symptoms. Here we present an unusual case of infective spondylodiscitis caused by Campylobacter fetus subsp. fetus .

Actinomyces are common commensals of the oral cavity, gastrointestinal tract and urogenital tract. They are anaerobic, Gram-positive, non-acid-fast bacilli, which can cause invasive infection and abscesses. We present the first reported case of supraglottitis and deep neck space abscess formation secondary to Actinomyces turicensis infection. The patient was managed with intravenous antibiotics, incision and drainage of a left parapharyngeal abscess and subsequent mediastinal abscess. After 6 weeks in hospital, the patient was successfully discharged to complete a 6-month course of oral amoxicillin.

Sinusitis is a common ailment a clinician comes across in their day-to-day practice. Simple as it may sound, it may become a very debilitating condition depending on the comorbidities of the patient and the organism involved. Rhizopus and Escherichia coli are less common organisms to affect the sinuses, but they are more common in immunocompromised patients such as patients with uncontrolled diabetes. Rhizopus can be a very debilitating infection as it erodes into the bone and blood vessels resulting in tissue necrosis. However, coinfection of both of these organisms is a very rare occurrence. Psoas abscess is also a less common infection in the immunocompetent patients but it is more common among the immunocompromised patients. It is extremely rare for both of these organisms to cause sinusitis in one patient, and for E. coli to simultaneously infect two different sites in the same patient. We report a case where a diabetic patient who had E. coli and Rhizopus coinfected sinusitis with simultaneous E. coli psoas abscess was successfully managed. The Rhizopus was treated with liposomal amphotericin B for 16 weeks while E. coli was treated with IV Meropenum. Furthermore, pneumocephalus is a condition that usually occurs following head trauma but the patient we are reporting developed pneumocephalus following Rhizopus sinusitis, which was treated with high-flow oxygen.

Introduction. Strongyloides stercoralis is an intestinal nematode that is endemic in tropical countries. It can have a variable presentation ranging from asymptomatic eosinophilia in immunocompetent hosts to disseminated disease with sepsis in immunocompromised hosts.

Case report. We report a case of chronic diarrhoea and decreased appetite in a 53-year-old man. He was a chronic alcoholic with diabetes, hypertension and dyslipidaemia and had earlier been treated for pulmonary tuberculosis. He was treated symptomatically for loose stools at a primary health care facility without relief. Following referral to our tertiary care centre, microscopic examination of the stool showed numerous larvae and a few eggs of Strongyloides stercoralis. Additionally, Aeromonas sobria was isolated from stool culture. The patient was discharged following improvement with a combination therapy of ivermectin, albendazole and ciprofloxacin. However, within 3 days, he was readmitted and succumbed to Escherichia coli sepsis.

Conclusion. Strongyloidiasis can be diagnosed easily using a very simple but often neglected investigation, namely stool microscopy. This provides an early diagnosis, based on which prompt treatment with the appropriate antihelminthics can be started, thereby reducing the probability of disseminated infection. Disseminated strongyloidiasis is a medical emergency with a poor prognosis, especially in an immunocompromised state. Such patients should be treated aggressively with antihelminthics. They must be monitored for sufficient duration in the hospital for early signs of complication. Their discharge from hospital should be planned based on a negative stool microscopy report in addition to clinical improvement, so as to decrease the mortality reported for both untreated and treated individuals.