The empirical use of aminoglycosides in Ludwig's angina based on bacterial analysis of 63 cases.

PURPOSES: To determine if the empirical use of aminoglycosides is justified in Ludwig's angina based on microscopy, culture and sensitivity results. METHODS: A retrospective analysis was done on patients that presented with Ludwig's angina to the Maxillofacial and Oral surgery department at the University of Pretoria. Demographical data was extracted from patient files. Pus specimens that were submitted as part of the initial surgical intervention were analysed. RESULTS: Sixty-three patients were included in the study with the majority, 76.19% (n=48/63), comprising males. The mean patient age was 38.6 years (range 6 months to 78 years). The majority of infections (87.3%) had an odontogenic aetiology (n=55/63). Forty-four percent of the patients had immunosuppressive co-morbidities (n=28/63). Streptococci contributed 71.26% (n=62/87) of the cultured bacteria. Similar bacteria were cultured in the immunocompromised and the immunocompetent patients (p=0.672). Ninety-two percent (n=57/62) of the streptococci cultured were sensitive to penicillin. The addition of aminoglycosides to the study sample would not have made a statistically significant difference (p=0.1556). CONCLUSION: Based on the findings of this study, the empirical use of aminoglycosides is not warranted in either immunocompromised or immunocompetent patients with Ludwig's angina.

A case report of Nocardia asiatica constrictive pericarditis in a patient with Human Immunodeficiency Virus.

Nocardiosis commonly affects the respiratory system and is a rare cause of purulent pericarditis. Invasive nocardial infections occur more frequently in patients with immunosuppression. A misdiagnosis as tuberculosis infection is not uncommon, especially in the context of immunosuppression in high burden tuberculosis settings. The risk factors and clinical features of the two disease entities overlap substantially. Misdiagnosis may lead to a delay in appropriate treatment and may result in poor outcomes. It is important to note that these conditions may also co-exist in the same patient. We describe, to the best of our knowledge, the first case of Nocardia asiatica pericarditis in a 32-year-old man with Human Immunodeficiency Virus infection. The patient was initially diagnosed in September 2020 with a lower respiratory tract infection and pulmonary tuberculosis was suspected. A chest radiograph, performed at admission, revealed a pericardial effusion and N. asiatica was cultured from a pericardial fluid specimen that was collected 5 days following admission. Despite a good initial clinical response to a combination of trimethoprim/sulfamethoxazole and imipenem/cilastatin, the patient demised after 16 weeks of treatment. Previous reports of laboratory confirmed nocardial pericarditis are also reviewed and summarized.

Spinal epidural abscess caused by Aspergillus spp masquerading as spinal tuberculosis in a person with HIV.

Spinal epidural abscess caused by Aspergillus spp is a debilitating form of invasive aspergillosis that can easily be misdiagnosed as spinal tuberculosis due to shared risk factors and clinical features. In this Grand Round, we describe a case of thoracic aspergillus spinal epidural abscess in a patient with underlying HIV infection. The initial diagnostic consideration was that of spinal tuberculosis. Consequently, despite positive microbiological cultures of Aspergillus fumigatus, antifungal therapy was delayed until histopathological evaluation of the affected tissue confirmed the presence of fungal hyphae. The patient showed an initial favourable response after surgical removal of the infected focus, but unfortunately never returned to premorbid functioning. This case highlights the importance of early diagnosis, urgent surgery, and prompt antifungal therapy for the management of aspergillus spinal epidural abscesses. Associated morbidity and mortality can be substantially increased if physicians fail to recognise this condition and do not institute appropriate and timely surgical and medical treatment.

Diagnostic accuracy of the BioFire FilmArray blood culture identification panel when used in critically ill patients with sepsis.

Sepsis accounts for high mortality rates in critical care units. Prompt and accurate identification of causative pathogens and initiation of appropriate antimicrobial therapy is critical for the appropriate management of patients in order to optimise clinical outcomes. The BioFire FilmArray blood culture identification (BCID) panel is a US Food and Drug Administration (FDA) approved rapid, multiplex polymerase chain reaction (PCR) assay that is able to identify a variety of bacteria, fungi and antimicrobial resistance determinants directly from positive blood cultures. The aim of this study was to evaluate the diagnostic performance of the BioFire FilmArray BCID panel against the gold standard of blood cultures. Seventy-eight positive blood cultures obtained from critically ill patients suspected of having sepsis were included in the study. Each bottle was processed with the BioFire FilmArray BCID panel as well as conventional culture methods. Diagnostic accuracy of the BioFire FilmArray BCID panel was determined. The assay demonstrated a high sensitivity and specificity for pathogen identification of 96.5% (95% CI, 91.3-99.0) and 99.7% (95% CI, 99.3-99.9), respectively. The findings of this study support the role of the BioFire FilmArray BCID panel in the management of critically ill patients with sepsis.

Clinical utility of the BioFire FilmArray Blood Culture Identification panel in the adjustment of empiric antimicrobial therapy in the critically ill septic patient.

Sepsis and septic shock are key contributors to mortality in critically ill patients and thus prompt recognition and management thereof is central to achieving improved patient outcomes. Early initiation of appropriate antimicrobial therapy constitutes a crucial component of the management strategy and thus early identification of the causative pathogen is essential in informing antimicrobial therapeutic choices. The BioFire FilmArray blood culture identification (BCID) panel is a US Food and Drug Administration (FDA) approved rapid, multiplex polymerase chain reaction assay for use on positive blood cultures. This study evaluated its clinical utility in the intensive care unit (ICU) setting, in terms of amendment of empiric antimicrobial therapy in critically ill patients with sepsis. The assay proved useful in this setting as final results were made available to clinicians significantly earlier than with conventional culture methods. This, in turn, allowed for modification of empirical antimicrobial therapy to more appropriate agents in 32% of patients. Additionally, the use of the BioFire FilmArray BCID panel permitted the prompt implementation of additional infection prevention and control practices in a sizeable proportion (14%) of patients in the study who were harbouring multidrug resistant pathogens. These findings support the use of the BioFire FilmArray BCID panel as a valuable adjunct to conventional culture methods for the diagnosis and subsequent management of critically ill patients with sepsis.

Laboratory evaluation of the BioFire FilmArray Pneumonia plus panel compared to conventional methods for the identification of bacteria in lower respiratory tract specimens: a prospective cross-sectional study from South Africa.

Lower respiratory tract infections are important causes of morbidity and mortality. The global increase in antimicrobial resistance necessitates rapid diagnostic assays. The BioFire FilmArray Pneumonia plus (FAPP) panel is a Food and Drug Administration-approved multiplex polymerase chain reaction assay that detects the most important etiological agents of pneumonia and associated antibiotic resistance genes, in approximately 1 hour. This study assessed the diagnostic performance of this assay by comparing it to conventional culture methods in the analysis of 59 lower respiratory tract specimens. The sensitivity and specificity of the FAPP panel for bacterial detection were 92.0% (95% confidence interval [CI], 80.8% to 97.8%) and 93.8% (95% CI, 91.1% to 95.3%) respectively. For detecting antibiotic resistance, the positive- and negative percent agreement were 100% (95% CI, 81.5% to 100.0%) and 98.5% (95% CI, 216 96.7% to 99.4%) respectively. The FAPP panel was found to be highly accurate in evaluating tracheal aspirate specimens from hospitalized patients.

Post-procedural Bacillus cereus septic arthritis in a patient with systemic lupus erythematosus.

INTRODUCTION: Bacillus species are often considered as contaminants when cultured from clinical samples. Bacillus cereus may be a pathogen in certain circumstances and is known to cause musculoskeletal infections. This report aims to educate clinicians and clinical microbiology laboratories on B. cereus musculoskeletal infections and to heighten awareness that Bacillus species should not always be dismissed as contaminants. CASE PRESENTATION: We report the case of a patient who presented to a tertiary hospital in Pretoria, South Africa, in November 2018 with B. cereus septic arthritis and underlying systemic lupus erythematosus (SLE). The isolate would otherwise have been dismissed as a contaminant had it not been for the crucial interaction between the laboratory and the treating clinicians. To our knowledge, this is the first case report of septic arthritis caused by B. cereus in an SLE patient where the organism was cultured from the joint specimen. Identification of the organism was performed using matrix-assisted laser desorption/ionisation mass spectrometry. MANAGEMENT AND OUTCOME: Definitive treatment was with intravenous vancomycin, continued for four weeks, in addition to arthroscopy and management of the underlying SLE. The patient had a good clinical outcome and regained full mobility. CONCLUSION: Musculoskeletal infections, specifically septic arthritis caused by B. cereus, are exceedingly rare infections. Immune suppression, trauma, prosthetic implants and invasive procedures are important risk factors for B. cereus musculoskeletal infections. Close collaboration with a multi-disciplinary team approach will effect the best outcome for complicated patients with B. cereus infections.

Genome sequence of a clinical Salmonella Enteritidis sequence type 11 strain from South Africa.

OBJECTIVES: The underlying resistance mechanism and phylogenetic relationship of a colistin-resistant Salmonella enterica serovar Enteritidis strain EC20120916 that resulted in fatal meningitis in an immunocompromised patient was investigated by whole-genome sequencing (WGS) analysis. METHODS: WGS of strain EC20120916 was performed on an Illumina MiSeq platform and annotation of the sequence was performed using the Prokaryotic Genome Annotation Pipeline (PGAP). Antimicrobial resistance genes, plasmid replicons and pathogenicity islands were identified. A phylogenetic tree was constructed using Parsnp and was edited with FigTree. RESULTS: The genome size of strain EC20120916 is 4 699 318 bp with a GC content of 55.2% and 4471 protein-coding genes. The aac(6')-laa gene, encoding resistance to aminoglycosides, was identified although this was not expressed phenotypically in the isolate. No colistin resistance-conferring mutations or plasmid-mediated mechanisms were identified to explain the colistin resistance. The strain was phylogenetically related to three international strains, although it was not close enough to suggest importation from outside of South Africa. CONCLUSION: This is the first report of a colistin-resistant Salmonella Enteritidis isolate causing meningitis in an immunocompromised patient in South Africa. The absence of colistin resistance-conferring mutations or plasmid-mediated resistance mechanisms suggest that a novel mechanism is responsible for the colistin resistance in this isolate. The isolate was acquired locally.

A rare case of Colistin-resistant Salmonella Enteritidis meningitis in an HIV-seropositive patient.

BACKGROUND: Non-typhoidal salmonellae (NTS) have been associated with invasive disease, notably meningitis, in immunocompromised individuals. Infections of this nature carry high rates of morbidity and mortality. Colistin resistance in salmonellae is a rare finding, more so in an invasive isolate such as cerebrospinal fluid (CSF). Colistin resistance has important infection control implications and failure to manage this phenomenon may lead to the loss of our last line of defence against multi-drug resistant Gram-negative organisms. To our knowledge, this is the first reported clinical case of colistin-resistant Salmonella Enteritidis meningitis in South Africa. CASE PRESENTATION: We report a case of a young male patient with advanced human immunodeficiency virus (HIV) infection who presented to hospital with symptoms of meningitis. Cerebrospinal fluid (CSF) cultured a Salmonella Enteritidis strain. Antimicrobial susceptibility testing (AST) of the isolate, revealed the strain to be colistin resistant. Despite early and aggressive antimicrobial therapy, the patient succumbed to the illness after a short stay in hospital. Subsequent genomic analysis of the isolate showed no presence of the mcr genes or resistance-conferring mutations in phoPQ, pmrAB, pmrHFIJKLME/arnBCADTEF, mgrB, and acrAB genes, suggesting the presence of a novel colistin resistance mechanism. CONCLUSION: Invasive non-typhoidal salmonellae infection should be suspected in patients with advanced immunosuppression who present with clinical features of meningitis. Despite early and appropriate empiric therapy, these infections are commonly associated with adverse outcomes to the patient. Combination therapy with two active anti-Salmonella agents may be a consideration in the future to overcome the high mortality associated with NTS meningitis. Colistin resistance in clinical Salmonella isolates, although a rare finding at present, has significant public health and infection control implications. The causative mechanism of resistance should be sought in all cases.