Anaerobic Gram-negative Bacilli Research Articles

Anaerobes in diabetic foot infections: pathophysiology, epidemiology, virulence, and management.

SUMMARYDiabetic foot infections (DFI) are a public health problem worldwide. DFI are polymicrobial, biofilm-associated infections involving complex bacterial communities organized in functional equivalent pathogroups, all including anaerobes. Indeed, multiple pathophysiological factors favor the growth of anaerobes in this context. However, the prevalence, role, and contribution of anaerobes in wound evolution remain poorly characterized due to their challenging detection. Studies based on culture reviewed herein showed a weighted average of 17% of patients with anaerobes. Comparatively, the weighted average of patients with anaerobes identified by 16S rRNA gene sequencing was 83.8%. Culture largely underestimated not only the presence but also the diversity of anaerobes compared with cultivation-independent approaches but both methods showed that anaerobic Gram-negative bacilli and Gram-positive cocci were the most commonly identified in DFI. Anaerobes were more present in deeper lesions, and their detection was associated with fever, malodorous lesions, and ulcer depth and duration. More specifically, initial abundance of Peptoniphilus spp. was associated with ulcer-impaired healing, Fusobacterium spp. detection was significantly correlated with the duration of DFI, and the presence of Bacteroides spp. was significantly associated with amputation. Antimicrobial resistance of anaerobes in DFI remains slightly studied and warrants more consideration in the context of increasing resistance of the most frequently identified anaerobes in DFI. The high rate of patients with DFI-involving anaerobes, the increased knowledge on the species identified, their virulence factors, and their potential role in wound evolution support recommendations combining debridement and antibiotic therapy effective on anaerobes in moderate and severe DFI.

Citrobacter Freundii Skin Infection in an Immunocompetent Subject Simulating Varicella: A Treatment-Resistant Case

Citrobacter spp infections in immunocompetent subjects are rare and mainly involve the urinary and respiratory tracts. We report a case of Citrobacter freundii skin infection in an immunocompetent patient simulating varicella and having resisted empirical treatment of common bacterial skin infections on 3 occasions. The patient was 26-years-old and worked in a mining area in Kayes, Mali. He had no previous medical or surgical history and consulted for diffuse papulopustules on the integument, simulating chickenpox, for which he had received empirical treatments of common bacterial skin infections without success. In view of the persistence and appearance of new lesions, he consulted us on 2nd November 2021, where a bacteriology showed Citrobacter freundii. The patient was treated with ceftazidime and gentamycin with success (according to the patient). Citrobacter spp are facultative anaerobic Gram-negative bacilli of the Enterobacteriaceae family, frequently found in water, soil, food and the intestines of animals and humans. They are known to cause a wide spectrum of infections affecting the urinary tract, liver, biliary tract, peritoneum, intestines, bone, respiratory tract, endocardium, wounds, soft tissue, meninges and bloodstream in immunocompromised subjects. Our case is atypical in its presentation, immunocompetent subject, clinical form simulating chickenpox without extracutaneous involvement and which raised the resistance of opportunistic germs to antibiotics.

Liver Abscesses Due to Fusobacterium nucleatum: A Case Series

Abstract Fusobacteriae are anaerobic gram-negative bacilli, classically involved in the development of septic thrombophlebitis of the internal jugular vein in Lemierre syndrome. The goal of this study is to describe the various presentations, treatment course, and outcomes of patients with Fusobacterium liver abscess(es) and review available literature on this topic. We retrospectively reviewed our microbiologic database for positive cultures of Fusobacteriae species in a tertiary care hospital from July 2018 through November 2022 and identified 5 cases of liver abscess that involved Fusobacterium nucleatum species. Patients presented with a syndrome of fever and chills, abdominal pain, and nausea and vomiting. Laboratory investigations revealed leukocytosis and transaminitis, and imaging revealed liver abscess(es). The identification of the F. nucleatum bacteria involved invasive aspiration of the abscess in all but one case, where it was identified on blood cultures. One patient had a florid picture of sepsis and acute respiratory distress syndrome. All patients responded well with intravenous antibiotics and were discharged home to complete a prolonged course until radiographic resolution. In 3 patients, history and imaging were suggestive of possible sources that may have hematogenously spread to the liver, with history of recent appendectomy in 1 patient, possible appendicitis on computed tomography of the abdomen in another patient, and recent dental manipulation in the third patient. In conclusion, Fusobacteriae should be included in the differential diagnosis of liver abscess, especially in the setting of recent appendicitis or dental disease. Effective treatment includes surgical drainage when feasible and prolonged course of antibiotics with goal of radiologic resolution.

Simultaneous detection and evaluation of Prevotella intermedia, Prevotella nigrescens, Prevotella loescheii, and Prevotella melaninogenica in subgingival plaque samples of chronic periodontitis and healthy individuals through multiplex polymerase chain reaction.

Prevotella is a Gram-negative anaerobic bacilli. The phenotypic characteristics of the various species of Prevotella are similar, which often makes it difficult in routine differentiation and identification of all the species. The purpose of the study was to detect and compare presence of Prevotella intermedia, Prevotella nigrescens, Prevotella melaninogenica, and Prevotella loescheii in subgingival plaque samples of chronic periodontitis and healthy individuals. Two hundred and thirty-six subjects were considered consisting of chronic periodontitis (128) and healthy (108) individuals. Subgingival plaque sample was collected in reduced transport fluid and analyzed. DNA extraction and polymerase chain reaction (PCR) were performed for genus Prevotella followed by positive samples were considered for the detection of selected species through multiplex PCR using specific primers. Out of 236 samples, 94.1% were positive for genus Prevotella. Out of 222 cases P. nigrescens showed the highest number of cases positive (59.5%) followed by P. melaninogenica (57.2%), P. intermedia (55.4%), and P. loescheii (40.1%). Species were analyzed individually between chronic periodontitis and healthy, P. intermedia, P. nigrescens, and P. loescheii showed greater positivity in healthy compared to chronic periodontitis. Positivity for P. melaninogenica was high in chronic periodontitis compared to healthy. The number of positive cases for species, when correlated with clinical parameters showed an increase in mean score for all clinical parameters assessed, suggesting the presence of variation in the prevalence of Prevotella species and geographic variation do exist in oral microflora. Findings suggest that they can be normal commensals and opportunistic.

Lipopolysaccharides (LPSs) as Potent Neurotoxic Glycolipids in Alzheimer's Disease (AD).

Lipopolysaccharides (LPSs) are microbiome-derived glycolipids that are among the most potent pro-inflammatory neurotoxins known. In Homo sapiens, the major sources of LPSs are gastrointestinal (GI)-tract-resident facultative anaerobic Gram-negative bacilli, including Bacteroides fragilis and Escherichia coli. LPSs have been abundantly detected in aged human brain by multiple independent research investigators, and an increased abundance of LPSs around and within Alzheimer’s disease (AD)-affected neurons has been found. Microbiome-generated LPSs and other endotoxins cross GI-tract biophysiological barriers into the systemic circulation and across the blood–brain barrier into the brain, a pathological process that increases during aging and in vascular disorders, including ‘leaky gut syndrome’. Further evidence indicates that LPSs up-regulate pro-inflammatory transcription factor complex NF-kB (p50/p65) and subsequently a set of NF-kB-sensitive microRNAs, including miRNA-30b, miRNA-34a, miRNA-146a and miRNA-155. These up-regulated miRNAs in turn down-regulate a family of neurodegeneration-associated messenger RNA (mRNA) targets, including the mRNA encoding the neuron-specific neurofilament light (NF-L) chain protein. While NF-L has been reported to be up-regulated in peripheral biofluids in AD and other progressive and lethal pro-inflammatory neurodegenerative disorders, NF-L is significantly down-regulated within neocortical neurons, and this may account for neuronal atrophy, loss of axonal caliber and alterations in neuronal cell shape, modified synaptic architecture and network deficits in neuronal signaling capacity. This paper reviews and reveals the most current findings on the neurotoxic aspects of LPSs and how these pro-inflammatory glycolipids contribute to the biological mechanism of progressive, age-related and ultimately lethal neurodegenerative disorders. This recently discovered gut-microbiota-derived LPS–NF-kB–miRNA-30b–NF-L pathological signaling network: (i) underscores a direct positive pathological link between the LPSs of GI-tract microbes and the inflammatory neuropathology, disordered cytoskeleton, and disrupted synaptic-signaling of the AD brain and stressed human brain cells in primary culture; and (ii) is the first example of a microbiome-derived neurotoxic glycolipid having significant detrimental miRNA-mediated actions on the expression of NF-L, an abundant filamentous protein known to be important in the maintenance of neuronal and synaptic homeostasis.

Multi-year comparison of VITEK® MS and 16S rRNA gene sequencing performance for the identification of rarely encountered anaerobes causing invasive human infections in a large Canadian region: can our laboratory abandon 16S rRNA gene sequencing?

BackgroundOur large regional laboratory routinely provides a definitive identification (ID) for 800-1,200 anaerobic bacteria per annum that cause invasive human infections. An increasing number of isolates (i.e., 10 to 13%) recovered from clinical specimens from these cases were more unusual or rarely isolated genera and/or species (i.e., ≤5 individual cases/annum). MethodsVITEK® MS (MALDI-TOF MS) is done initially on all anaerobic bacteria, but rare isolates undergo in-house PCR/sequencing when proteomics provides a wrong ID or no results despite repeat testing. A clinical microbiologist in consultation with the Infectious Diseases service approves molecular analyses. This multi-year comparison (2014-19) of the performance of MALDI-TOF MS and 16S rRNA gene sequencing using the IDNS® SmartGene bacterial dataset shows both method's abilities to provide a genus-level and/or species-level ID for rare isolates. Results489 rare anaerobes were recovered from a variety of clinical specimens: 57% blood cultures, 19% other sterile fluids, 14% sterile tissues, 8% deep wounds/abscesses, and 2% prosthetic implants. 16S rRNA gene sequencing gave an accurate genus-vs. species level ID for 487/489 (99.6%) and 401/489 (82.0%) of isolates respectively. Accurate genus-vs species-level ID were obtained by MALDI-TOF MS for 269/489 (53.4%) and 187/489 (37.3%) of isolates respectively. MALDI-TOF MS gave wrong or no results for 35.1% of Gram-negative anaerobic cocci (GNAC), 62% of Gram-negative anaerobic bacilli (GNAB), 30.8% of Gram-positive anaerobic cocci (GPAC) and 46.3% of Gram-positive anaerobic bacilli (GPAB). Neither method gave an ID for one GNAB and one GPAC isolate. MALDI-TOF MS genus-level ID of GNAC and genus/species-level ID of GPAB improved during the study but its performance remained stable for genus- or species-level ID of other organism groups. ConclusionsMALDI-TOF MS provides accurate ID for most common anaerobes, but molecular analyses need to be available for rare isolates. Large complex laboratories should have a workflow for sending rare isolates for 16S rRNA gene sequencing in invasive cases where a definitive ID is clinically required.

Bacteriological profile of anaerobes in deep-seated abscess of patients attending a tertiary care hospital

Background: Anaerobes are recognized as important human pathogens causing severe life threatening exogenous and endogenous infection if left untreated. Anaerobes are one of the most neglected pathogens in various clinical samples due to the problem in sample handling, technical difficulties in their cultivation, and identification along with prolonged turnaround time. Aims and Objectives: The present study was undertaken to identify the different anaerobic organisms associated with deep seated abscess and their association with various risk. Materials and Methods: Pus and fluid sample collected in sterile syringe or swab stick were immediately put in RCM and taken to the laboratory. Gram staining, ZN stain, and culture--both aerobic and anaerobic were done. Obligate anaerobes were checked for aerotolerance. Subcultures were done for identification of species level by Gram stain, colony morphology, biochemical tests, and final identification that were done by the Vitek 2 system. Results: Out of the 170 samples, 144 (84.70%) were culture positive and the rest 26 (15.29%) were culture negative; 101 (70.1%) were aerobic, 23 (16%) anaerobes, and 20 (13.9%) mixed aerobic and anaerobic. A total of 51 obligate anaerobes were isolated from various samples. Out of which 32 (62.74 %) anaerobic Gram-positive cocci-Peptostreptococcus anaerobious being the most common and 13 (25.49%) anaerobic Gram-negative bacilli --Bacteroids fragilis being most common and 6 (11.76%) were anaerobic Gram-positive bacilli - Actinomyces meyeri being the most common. Diabetes mellitus was a significant associated factor. Maximum number of anaerobes was isolated from abscess over oral cavity followed by gangrenous foot, scrotal abscess, and diabetic foot. Conclusion: Anaerobes are an important cause of deep-seated abscess—mostly being polymicrobial in nature. Incision--drainage and proper antibiotic therapy is necessary for their early control and prevention of complications.

A discrepant presentation of bacteremia in the emergency department linked to a Fusobacterium nucleatum infection: a case report

BackgroundFusobacterium nucleatum is an anaerobic bacterium mainly responsible for acute or chronic infection of the ear, nose, and throat, potentially bacteremic with a risk of extraoral metastatic infection. Bacteremia occurs mainly in the elderly or in immunodeficient individuals, with high mortality. F. nucleatum is not the first cause of tonsillar infection in emergency departments, which are more often the consequence of a viral or streptococcal infection, but it is a risk factor for severe bacterial infection, especially in a viral pandemic context.Case presentationA 25-year-old European woman with no history presented to the emergency department with fever (38.9 °C), pharyngeal symptoms, intermittent headaches, and alteration of general condition. On examination, she presented odynophagia associated with moderate tonsillar hypertrophy, her neck was painful but flexible. A rapid diagnostic test for beta-hemolytic group streptococcus was negative. First biological analyses revealed an inflammatory syndrome with C-reactive protein of 76 mg/L. Procalcitonin was measured secondarily, and was 2.16 µg/L. Faced with discordant clinical and biological findings, a lumbar puncture was performed, which came back negative. At hour eight, hypotension was observed but corrected after filling with physiological serum. The patient was hospitalized for monitoring, based on a hypothesis of severe viral presentation. At hour 24, pyrexia confirmed this hypothesis. A spontaneous but transient improvement and no new hemodynamic event led to early discharge. At day three, she was rehospitalized for increased and continuous headaches, without hemodynamic severity. A broad-spectrum probabilistic antibiotic therapy of ceftriaxone and metronidazole was started due to first blood cultures positive for anaerobic Gram-negative bacilli, while waiting for identification of the pathogen. Three days later, F. nucleatum was identified. According to the microbiological results, antibiotic therapy was adapted with amoxicillin and clavulanic acid, and no further complications were observed during clinical or complementary examinations. The final diagnosis was a F. nucleatum oropharyngeal infection complicated by bacteremia, without metastatic spread.ConclusionThe etiologies of tonsillar infection are not limited to benign viruses or bacteria. These should not be overlooked in emergency medicine, especially when the clinical presentation is discrepant. A combination of early bacterial investigations as blood culture and close clinical monitoring is the only safe way to detect bacteremia, especially in immunocompetent patients.

Comparison of culture and polymerase chain reaction-restriction fragment length polymorphism for identification of various Capnocytophaga species from subgingival plaque samples of healthy and periodontally diseased individuals.

Introduction:Capnocytophaga are facultative anaerobic Gram-negative bacilli and recognized as opportunistic pathogens of various extraoral infections. Only a few studies attempted to identify all the seven species of Capnocytophaga phenotypically and genotypically in healthy individuals and patients with chronic periodontitis. Studies to determine the prevalence of Capnocytophaga in subgingival plaque samples from healthy individuals, chronic gingivitis and periodontitis among Indian population are lacking.Aim:The aim of this study was to identify and compare the presence of Capnocytophaga species phenotypically through microbial culture and biochemical tests and genotypically through polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) in subgingival plaque of healthy individuals and patients with chronic gingivitis and chronic periodontitis.Materials and Methods:A total of 300 subjects, 100 each with gingivitis, periodontitis and periodontally healthy gingiva subjected, were included. Subgingival plaque was collected and was cultured for phenotypic identification (microbial culture and biochemical test), and for genotypic identification, DNA extraction was done and PCR-RFLP analysis was performed to identify the genus Capnocytophaga and also to identify different species of Capnocytophaga.Results:Of 300 individuals, Capnocytophaga species were identified from 237 (79%) individuals by PCR and 82 (27.33%) by culture. The prevalence of Capnocytophaga ochracea was found to be higher with both the methods followed by Capnocytophaga gingivalis and Capnocytophaga granulosa. Capnocytophaga genospecies, Capnocytophaga leadbetteri and Capnocytophaga Sputigena were isolated only by culture with very low prevalence that is 1.33%, 1.33% and 0.66%, respectively. We could not get any isolate of Capnocytophaga haemolytica by any of the two methods.Conclusion:Capnocytophaga species could be found in gingival sulci as well as periodontal pockets and can be detected by culture and PCR-RFLP. However, higher prevalence of these species in healthy compared to disease requires further analysis to determine their role in healthy and diseased periodontium.

SALMONELLA ENTERITIDIS BACTEREMIA AND EMPYEMA FORMATION

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: Nontyphoidal Salmonellae are anaerobic gram-negative bacilli that most commonly present with gastroenteritis but can cause extra-intestinal manifestations such as bacteremia, osteomyelitis, septic arthritis, endocarditis, endovascular infections, and abscesses. They have rarely been implicated in pulmonary infections. Here we describe a patient with chronic pleural effusions who had Salmonella enteritidis bacteremia and subsequent development of an empyema. CASE PRESENTATION: A 52 year-old male with history of chronic myelogenous leukemia (CML) who has been on dasatinib for the past 8 years, initially presented with fever, abdominal pain, and watery diarrhea. He was found to have Salmonella enteritidis bacteremia, improved with IV Ceftriaxone, and was discharged with a 10 day oral Cefdinir course. A CT abdomen/pelvis done during this admission was negative for intra-abdominal pathology but did note bilateral pleural effusions. He then presented one month later with cough, shortness of breath, and left-sided pleuritic chest pain. He was found to be hypoxic with labs significant for leukocytosis to 33 x10^9/L. CT chest revealed a large left pleural effusion with septations and pleural enhancement concerning for an empyema. Diagnostic thoracentesis was performed with drainage of purulent fluid and cultures subsequently growing Salmonella enteritidis. He underwent VATS which revealed a complex multiloculated empyema entrapping the entire left hemithorax, dense adhesions between the lung and the mediastinum, chest wall, and diaphragm, and a thick fibrous peel entrapping the left lung. Complete open decortication was performed, and a chest tube was placed. He improved clinically and was started on Ciprofloxacin for prolonged course. DISCUSSION: This patient initially presented with acute gastroenteritis due to Salmonella enteritidis, developed secondary bacteremia, and was treated with appropriate antibiotics. He later presented with dyspnea and cough with imaging concerning for a loculated pleural effusion and empyema. This was in the setting of chronic benign transudative pleural effusions likely secondary to his dasatinib therapy. This effusion was likely seeded when he was bacteremic, leading to development of an empyema. His history of malignancy and chronic lymphopenia likely also predisposed him to severe extraintestinal Salmonella infection given his impaired cellular immunity. CONCLUSIONS: Non-typhi Salmonella are not routinely associated with pleuropulmonary disease but can be a rare cause of empyema. REFERENCE #1: Acheson, D., & Hohmann, E. L. (2001). Nontyphoidal Salmonellosis. Clinical Infectious Diseases, 32(2), 263-269. https://doi.org/10.1086/318457 REFERENCE #2: Pathmanathan, S., Welagedara, S., Dorrington, P., & Sharma, S. (2015). Salmonella empyema: a case report. Pneumonia (Nathan Qld.), 6, 120–124. https://doi.org/10.1007/BF03371465 DISCLOSURES: No relevant relationships by Amy Amornmarn, source=Web Response No relevant relationships by Katherine Gershner, source=Web Response No relevant relationships by Almutasem Hamed, source=Web Response

Etiology and antimicrobial susceptibility profiles of anaerobic bacteria isolated from clinical samples in a university hospital in Madrid, Spain

BackgroundThe anaerobic infection management is usually based on empirical treatment because anaerobic culture techniques take a long time due to their fastidious nature. The aim of this study was to analyze the etiological profile of severe anaerobic infections and AST data from clinical anaerobic bacteria isolated in a tertiary hospital in Madrid (Spain). Material and methodsA consecutive study was carried out over 19 months in Ramón y Cajal Universitary Hospital, Madrid. Clinical samples were processed in appropriate anaerobic media and incubated using Anoxomat system. Identification was performed by MALDI-TOF. AST were determined with gradient diffusion method using EUCAST (penicillin, co-amoxiclav, imipenem, clindamycine and metronidazole) or CLSI (cefoxitin) breakpoints. ResultsDuring the period of study, 503 anaerobic microorganisms isolated from 424 clinical samples were included. Twenty-six percent of the cultures were monomicrobial, while 70.0% also contained aerobic bacteria. The most common source of infection was abscesses (26%), while blood infections represented the 11%. Anaerobic gram-negative bacilli were predominant (41%), being Bacteroides fragilis (13%) the most prevalent overall; anaerobic gram-positive bacilli represented 35%, anaerobic gram-positive cocci 19% and anaerobic gram-negative cocci 5%. Metronidazole and imipenem were the most effective agents tested against anaerobic bacteria, while clindamycin presented higher resistance rates. ConclusionAntimicrobial susceptibility surveillance of anaerobic bacteria should be performed to monitor changes in resistance patterns and to be able to optimize empiric antimicrobial treatment. Reliable species identification and quick reporting of results would guide clinicians to select the optimal antimicrobial therapy.

Characterization of a carbapenem-resistant Citrobacter amalonaticus coharbouring bla IMP-4 and qnrs1 genes

Introduction. Members of the genus Citrobacter are facultative anaerobic Gram-negative bacilli belonging to the Enterobacterales [Janda J Clin Microbiol 1994; 32(8):1850-1854; Arens Clin Microbiol Infect 1997;3(1):53-57]. Formerly, Citrobacter species were occasionally reported as nosocomial pathogens with low virulence [Pepperell Antimicrob Agents Chemother 2002;46(11):3555-60]. Now, they are consistently reported to cause nosocomial infections of the urinary tract, respiratory tract, bone, peritoneum, endocardium, meninges, intestines, bloodstream and central nervous system. Among Citrobacter species, the most common isolates are C. koseri and C. freundii, while C. amalonaticus has seldom been isolated [Janda J Clin Microbiol 1994; 32(8):1850-1854; Marak Infect Dis (Lond) 2017;49(7):532-9]. Further, Citrobacter spp. are usually susceptible to carbapenems, aminoglycosides, tetracyclines and colistin [Marak Infect Dis (Lond) 2017;49(7):532-9].Hypothesis/Gap Statement. As C. amalonaticus is rare, only one clinical isolate, coharbouring carbapenem resistance gene bla IMP-4 and quinolone resistance gene qnrs1, has been reported.Aim. To characterize a carbapenem-resistant C. amalonaticus strain from PR China coharbouring bla IMP-4 and qnrs1.Methodology. Three hundred and forty nonrepetitive carbapenem-resistant Enterobacterales (CRE) strains were collected during 2011-2018. A carbapenem-resistant C. amalonaticus strain was detected and confirmed using a VITEK mass spectrometry-based microbial identification system and 16S rRNA sequencing. Minimum inhibitory concentrations (MICs) for clinical antimicrobials were obtained by the broth microdilution method. Whole-genome sequencing (WGS) was performed for antibiotic resistance gene analysis, and a phylogenetic tree of C. amalonaticus strains was constructed using the Bacterial Pan Genome Analysis (BPGA) tool. The transferability of the resistance plasmid was verified by conjugal transfer.Results. A rare carbapenem-resistant C. amalonaticus strain (CA71) was recovered from a patient with cerebral obstruction and the sequences of 16S rRNA gene shared more than 99 % similarity with C. amalonaticus CITRO86, FDAARGOS 165. CA71 is resistant to β-lactam, quinolone and aminoglycoside antibiotics, and even imipenem and meropenem (MICs of 2 and 4 mg l-1 respectively), and is only sensitive to polymyxin B and tigecycline. Six antibiotic resistance genes were detected via WGS, including the β-lactam genes bla IMP-4, bla CTX-M-18 and bla Sed1, the quinolone gene qnrs1, and the aminoglycoside genes AAC(3)-VIIIa, AadA24. Interestingly, bla IMP-4 and qnrs1 coexist on an IncN1-type plasmid (pCA71-IMP) and successfully transferred to Escherichia coli J53 via conjugal transfer. Phylogenetic analysis showed that CA71 is most similar to C. amalonaticus strain CJ25 and belongs to the same evolutionary cluster along with seven other strains.Conclusion. To the best of our knowledge, this is the first report of a carbapenem-resistant C. amalonaticus isolate coharbouring bla IMP-4 and qnrs1.

Fournier Syndrome-Surgical and Intensive Care Treatment

Fournier’s Gangrene, also referred to as necrotising fasciitis, Mellene Syndrome or Fournier Syndrome (FS), is a soft-tissue acute infection of the perinium with secondary necrotising cellulitis caused by anaerobic germs or gram-negative bacilli or both. This infection may develop in apparently normal skin, affects the tegumentary and fascial planes but it affects the muscle - aponeurotic plane very rarely dissecting the necrotic tissues, as it rapidly moves towards sepsis, with multiple failure of the organs and death. Treatment consists of agressive surgical debridement, broad spectrum antibiotic therapy, hyperbaric oxiygen therapy (OHB) and other complementary actions.

Clinico-microbiological spectrum of anaerobic pyogenic infections in an Indian tertiary care teaching hospital: A two-year study.

Introduction:Anaerobes are important however the most neglected pathogens. Timely isolation of anaerobes can guide the clinician about the correct course of clinical treatment and thus reduce the mortality and also the problem of antimicrobial resistance.Materials and Methods:Tissue and/or pus aspirates were collected aseptically from infectious sites in the Robertson's cooked meat medium (RCM) and sent to anaerobic bacteriology laboratory for culture. Subcultures from RCM for each sample were done on neomycin blood agar and 5% sheep blood agar along with metronidazole disc (5μg). The plates were incubated in an anaerobic jar using GasPak for 72 hrs. The preliminary identification was performed by standard biochemical tests for both obligate and facultative anaerobic isolates. Speciations of obligate anaerobes were performed by Vitek 2 automated system.Results:Obligate anaerobes either single or polymicrobial were obtained in 38/216 (14.5 %) samples processed during the study period. Polymicrobial infections were reported in 21/216 (55.26%) samples and most commonly with obligate anaerobic gramnegative bacilli i.e. Prevotella-Porphyromonas and Bacteroides fragilis group. Most common monomicrobial anaerobic infections were observed with Veillonella spp. (n=4) and Porphyromonas spp. (n=4) followed by Bacteroides fragilis (n=3). Obligate anaerobes were predominantly isolated from skin and soft tissue infections (n=14) followed by surgical site infections (n=8).Conclusion:Although most of the infections are polymicrobial, a rise in the incidence of monomicrobial anaerobic infections has been noticed. Therefore, the performance of anaerobic cultures along with aerobic cultures is much needed for complete bacterial work-up of specimens from infectious sites and better patient management.

A rare and fatal case of Terrisporobacter glycolicus bacteremia: Case report and review of literature

Background: Terrisporobacter glycolicus (formerly known as Clostridium glycolicum) is a rare cause of infection and emerging anaerobic pathogen. It is a gram-positive, rod shaped obligate anaerobic organism, first identified in 1963 by Gaston and Stadman. However, the first human infection was reported only in 2007, more than 4 decades after its discovery. There are few published case reports reporting these gram-positive bacilli causing infection to human and mostly as part of a polymicrobial infection. Here, we described a case of septicaemia with mortality. Case description: We described a case of a 78-year-old gentleman with multiple co-morbidities and sacral sore admitted for altered sensorium due to cerebrovascular accident with uremia. During admission he developed urinary tract infection and was treated with intravenous cefuroxime, which he has responded well. However, he deteriorated later with poor oral intake and reduced in Glasgow coma scale of 8/15. Blood culture from anaerobic bottle isolated greyish colonies on anaerobic plate after 48 h of incubation, susceptible to metronidazole. By using Vitex 2.0 system, there was low discrimination between T. glycolicus and Clostridium sporogenes. The isolate was later identified by Matrix-assisted laser desorption/ionization – time of flight (MALDI-TOF) mass spectrometry as Terrisporobacter glycolicus. The result from the reference laboratory showed two anaerobic organisms were isolated (Gram-positive anaerobic bacilli and gram-negative anaerobic bacilli). The gram-positive anaerobic bacilli was identified as Terrisporobacter glycolicus which was susceptible to penicillin [minimum inhibitory concentration (MIC) of 0.380 ug/mL], amoxycillin-clavulanate (MIC of 0.750 mg/mL), imipenem (MIC of 0.500 ug/mL), clindamycin (MIC of 0.064 ug/mL) and metronidazole (MIC of 1.000 ug/mL). The patient however deteriorated further and was decided for DNR status. He succumbed to illness on day 15 of admission. Discussion: MALDI-TOF MS has become the method of choice for identification of anaerobic bacteria, replacing 16S rRNA gene sequencing and gas–liquid chromatography. The advent of MALDI-TOF MS has demonstrated increased specificity, cost-effectiveness, and decreased turnaround time. Conclusion: Infection by this organism could be fatal in elderly patient with co-morbidities. In this group of patients, the presentation is usually atypical. In addition, up-to-date laboratory identification such as MALDI-TOF plays important role in confirming the identity of this organism.

Identification and confirmation of Laribacter hongkongensis bacteremia in a patient with neutropenic sepsis in Malaysia

Background: Laribacter hongkongensis is increasingly being reported worldwide since its discovery as a potential pathogen two decades ago in Hong Kong. An organism of fresh-water environments, L. hongkongensis is a motile facultative anaerobic gram-negative bacilli under the family Neisseriaceae. Case description: Here, we describe a case of L. hongkongensis in a 54-year old male with stage IV Hodgkin's Lymphoma, complicated with neutropenic sepsis. Upon an elective admission for his second cycle of chemotherapy, the patient presented with a high-degree pyrexia and a history of intermittent diarrhea, followed by severe neutropenia and thrombocytopenia. A pure growth of non-lactose fermenters, identified as L. hongkongensis via mass spectrometry (MALDI-ToF) and 16S rDNA sequencing, was isolated from blood culture. Discussion: Further phenotypic antibiotic sensitivity testing and interpretation of MIC breakpoints was commenced in accordance to the performance standards by CLSI for non-Enterobacteriaceae. Molecular detection of associated antibiotic resistance genes disclosed the amplification of a quinolone resistance gene (qnrS). The patient achieved prompt clinical improvement with Piperacillin-Tazobactam, which was started empirically by the primary team, as evidenced by the clearance of this organism from repeated blood cultures along with resolution of fever and normalization of blood counts. Conclusion: Because of its overlapping phenotypic characteristics with many other non-Enterobacteriaceae, L. hongkongensis may be easily overlooked if conventional bench methods were to be used alone. This highlights the need for further improvements of selective media as well as the employment of mass spectrometry and molecular methods as effective diagnostic aids in the pursuit of isolating this potentially emerging pathogen.

Elucidation of Proteus mirabilis as a Key Bacterium in Crohn’s Disease Inflammation

Proteus spp, Gram-negative facultative anaerobic bacilli, have recently been associated with Crohn's disease (CD) recurrence after intestinal resection. We investigated the genomic and functional role of Proteus as a gut pathogen in CD. Proteus spp abundance was assessed by ure gene-specific polymerase chain in 54 pairs of fecal samples and 101 intestinal biopsies from patients with CD and healthy controls. The adherence, invasion, and intracellular presence of 2 distinct isolates of Proteus mirabilis in epithelial cells were evaluated using immunofluorescence and electron microscopy. Intracellular gene expression profiles and regulated pathways were analyzed by RNA sequencing and KEGG pathway analysis. Biologic functions of 2 isolates of P mirabilis were determined by invitro cell culture, and invivo using conventional mice and germ-free mice. Proteus spp were significantly more prevalent and abundant in fecal samples and colonic tissue of patients with CD than controls. A greater abundance of the genus Fusobacterium and a lesser abundance of the genus Faecalibacterium were seen in patients with CD with a high Proteus spp abundance. All 24 Proteus monoclones isolated from patients with CD belonged to members of P mirabilis lineages and 2 isolates, recovered from stool or mucosa, were used in further studies. Mice gavaged with either P mirabilis strain had more severe colonic inflammation. Co-culture of the isolates with epithelial cell lines showed bacterial adherence, invasion, increased production of pro-inflammatory cytokines IL-18 and IL-1α, and cell necrosis. Both isolates induced key pro-inflammatory pathways, including NOD-like receptor signaling, Jak-STAT signaling, and MAPK signaling, and induced pro-inflammatory genes and activated inflammation-related pathways in gnotobiotic mice. P mirabilis in the gut is associated with CD and can induce inflammation in cells and animal models of colitis. P mirabilis can act as a pathobiont and play a crucial role in the pathogenesis of CD.

ATYPICAL PRESENTATION OF LEMIERRE'S SYNDROME WITH ISOLATED INVOLVEMENT OF THE EXTERNAL JUGULAR VEIN

SESSION TITLE: Medical Student/Resident Chest Infections Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Lemierre’s syndrome is a life-threatening complication of pharyngitis leading to internal jugular vein (IJV) thrombophlebitis with pulmonary septic embolisation. Isolated external jugular vein (EJV) thrombophlebitis is rare. CASE PRESENTATION: A 35-year-old woman presented with one day of acute pleuritic chest pain. She had fever, chills, throat pain, dysphagia, malaise, and headache for 2 weeks. On presentation, she had trismus, extensive tender cervical lymphadenopathy with swelling on the left side of the neck, erythematous posterior pharynx and left enlarged erythematous tonsillar pillars without exudates. Blood showed leucocytosis with neutrophil predominance, elevated D-dimer, CRP, elevated bilirubin with normal liver enzymes, low platelets, low albumin, and blood culture revealed Fusobacterium necrophorum. Contrast CT scan soft tissue of the neck showed left tonsillar pillar enlargement with micro-abscesses and extension of inflammation into the left submandibular, parotid, and cervical space with thrombosis of the left EJV. Extension of inflammation into the retro-pharyngeal space was noted. CT Angiogram of Chest revealed bilateral peripheral opacities with cavitation in the right upper lobe and left lower lobe consistent with septic emboli. IJV revealed no thrombosis. A diagnosis of Lemierre’s syndrome was made. The patient improved on antibiotic therapy. DISCUSSION: Lemierre’s syndrome is a rare potentially lethal complication of oropharyngeal infection occurring mainly in young adults characterised by septic thrombophlebitis of the IJV with embolisation to lungs. It is rare (3.6 cases/million/year) with a mortality rate of >15%. 1,2. The common causative organisms are anaerobic gram-negative bacilli from the genus Fusobacterium mainly F. necrophorum.3 The oropharyngeal infection spreads to IJV from local oropharyngeal veins. Lymphatic spread and direct extension of infection also occur. However, in some patients, the venous drainage allows direct propagation of thrombophlebitis into the EJV.3 Patients present with fever, sore throat, neck swelling, pleuritic chest pain with cervical lymphadenopathy. Leucocytosis, elevated ESR, CRP, bilirubin and thrombophilia are seen. CT scan of the soft tissue of the neck and chest with contrast is required for diagnosis. CONCLUSIONS: In patients with severe pharyngitis and pulmonary septic emboli Lemierre’s syndrome must be suspected and the venous system of the neck should be closely visualised for evidence of thrombophlebitis of both IJV and EJV. Reference #1: Nall RW. Sore Throat. In: Stern SC, Cifu AS, Altkorn D. eds. Symptom to Diagnosis: An Evidence-Based Guide, 4e New York, NY: McGraw-Hill. http://accessmedicine.mhmedical.com/content.aspx?bookid=2715§ionid=228250877. Accessed May 28, 2020.2. Reference #2: Barlam TF, Kasper DL. Approach to the Acutely Ill Infected Febrile Patient. In: Jameson J, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 20e New York, NY: McGraw-Hill. http://accessmedicine.mhmedical.com/content.aspx?bookid=2129§ionid=183880456. Accessed May 28, 2020 Reference #3: Format:Reicher J, Brooke S, Arnold D, Counter P, Abdelgalil A. An unusual case of cavitating pulmonary nodules: Lemierre's syndrome with isolated involvement of the external jugular vein. BJR Case Rep. 2018;4(3):20170093. Published 2018 Feb 22. doi:10.1259/bjrcr.20170093 DISCLOSURES: No relevant relationships by Anomadarshi Barua, source=Web Response No relevant relationships by padmanabhan krishnan, source=Web Response No relevant relationships by Litty Mathews, source=Web Response No relevant relationships by Qasim Sheikh, source=Web Response No relevant relationships by Sarita Singh, source=Web Response

Breast Abscesses Caused by Anaerobic Microorganisms: Clinical and Microbiological Characteristics.

The objectives of this study were to report the antimicrobial susceptibility of 35 clinically significant anaerobic bacteria isolated from breast abscesses between March 2017 and February 2020 in a tertiary hospital in Granada (Spain) and to describe key clinical features of the patients. Species identification was performed mainly by MALDI-TOF MS. Antimicrobial susceptibility tests were carried out against benzylpenicillin, amoxicillin–clavulanic acid, imipenem, moxifloxacin, clindamycin, metronidazole, and piperacillin–tazobactam using the gradient diffusion technique and European Committee on Antimicrobial Susceptibility Testing EUCAST breakpoints (except for moxifloxacin). The most frequent anaerobes were Finegoldia magna (31.4%; n = 11), Actinomyces spp. (17.1%; n = 6), Propionibacterium spp. (17.1%; n = 6), and Prevotella spp. (14.2%; n = 5). Imipenem, amoxicillin–clavulanic acid, and piperacillin–tazobactam were universally active against all genera tested. High overall resistance rates to clindamycin were observed, especially for Gram-positive anaerobic cocci (56.2%) and Gram-positive anaerobic bacilli (38.4%). High resistance rates to metronidazole were also observed for Gram-positive (76.9%) and Gram-negative anaerobic bacilli (50%). High resistance rates to moxifloxacin were found for Gram-negative anaerobic bacilli (50%) and Gram-positive anaerobic cocci (31.2%). No breast abscess cases of Bacteroides spp. were detected. Routine antimicrobial susceptibility testing for anaerobes in breast abscesses may contribute to allow empirical therapies to be selected in accordance with local data on resistant strains.

Trends and Impact in Antimicrobial Resistance Among Bacteroides and Parabacteroides Species in 2007-2012 Compared to 2013-2017.

Purpose: The aim of this study was to analyze the susceptibility of Bacteroides and Parabacteroides spp. strains, isolated from patients hospitalized in the clinical hospital in Poland to penicillin, amoxicillin with clavulanic acid, imipenem, clindamycin, and metronidazole. Methods: We analyzed susceptibility of 476 isolates to routinely use for the treatment of anaerobic bacterial infections antibiotics. E test method was used to determining the minimal inhibitory concentration values. To show the trend of drug resistance, we compared data from two periods within the years 2003-2017. Results: Research results indicate that the problem of resistance is mainly related to strains belonging to non-fragilis Bacteroides. In the analyzed periods, there was an increase in the percentage of clindamycin-resistant isolates (35.21% vs. 53.33%), amoxicillin/clavulanic acid (2.83% vs. 8.15%), and imipenem (1.41% vs. 3.7%). In isolates belonging to Parabacteroides distasonis, we observed a constant high (∼50%) percentage of clindamycin-resistant strains. The overwhelming majority of B. fragilis strains were resistant to penicillin (>95%) and about 20% of the isolates were not susceptible to clindamycin. Conclusions: Clindamycin, due to the high and increasing percentage of resistant strains, may not be a good choice in the empirical therapy of infections caused by Bacteroides and P. distasonis. Our study highlighted the importance of a routine or at least periodic monitoring of antimicrobial susceptibility of anaerobic Gram-negative bacilli, providing important information for appropriate therapy. The study shows that infection caused (or suspected of being caused) by Bacteroides and Parabacteroides spp. can be empirically treated with metronidazole or imipenem.