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Volume 4,
Issue 5,
2017
Volume 4, Issue 5, 2017
- Case Report
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- Urinary Tract and Reproductive Organs
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16S rRNA deep sequencing identifies Actinotignum schaalii as the major component of a polymicrobial intra-abdominal infection and implicates a urinary source
More LessIntroduction. It can be difficult to catalogue the individual organisms comprising polymicrobial patient infections, both because conventional clinical microbiological culture does not facilitate the isolation and enumeration of all members of a complex microbial community, and because fastidious organisms may be mixed with organisms that grow rapidly in vitro. Empiric antimicrobial treatment is frequently employed based on the anatomical site and the suspected source of the infection, especially when an appropriately collected surgical specimen is not obtained.
Case presentation. We present a case of an intra-abdominal infection in a patient with complex anatomy and recurrent urinary tract infections. Imaging did not reveal a clear source of infection, no growth was obtained from urine cultures and initial abdominal fluid cultures were also negative. In contrast, 16S rRNA deep sequencing of abdominal fluid samples revealed mixed bacterial populations with abundant anaerobes, including Actinotignum schaalii (Actinobaculum schaalii). Ultimately, only Enterobacter cloacae complex and meticillin-resistant Staphylococcus aureus, both of which were identified by sequencing, were recovered by culture.
Conclusion. The clinical application of 16S rRNA deep sequencing can more comprehensively and accurately define the organisms present in an individual patient's polymicrobial infection than conventional microbiological culture, detecting species that are not recovered under standard culture conditions or that are otherwise unexpected. These results can facilitate effective antimicrobial stewardship and help elucidate the possible origins of infections.
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- Blood/Heart and Lymphatics
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Streptococcus suis serotype 9 endocarditis and subsequent severe meningitis in a growing pig despite specific bactericidal humoral immunity
More LessIntroduction. Meningitis and endocarditis are common pathologies of Streptococcus suis infections in pigs and humans. S. suis serotype 9 strains contribute substantially to health problems in European pig production, and immune prophylaxis against this serotype is very difficult.
Case presentation. We report the clinical course and histopathological picture of a 10-week-old growing pig following experimental intravenous infection with S. suis serotype 9. The piglet showed rapid onset of severe clinical signs of meningitis 11 days post-intravenous challenge following prime-booster vaccination. Histopathological findings revealed a diffuse fibrinosuppurative leptomeningitis. Additionally, a polyphasic endocarditis valvularis thromboticans with numerous bacterial colonies was diagnosed. Bacteriological culture of the brain and the mitral valve confirmed association with the challenge strain. However, virulent serotype 2 and 9 strains were killed in the blood of this piglet ex vivo prior experimental infection.
Conclusion. Endocarditis induced by S. suis infection might develop and persist despite the presence of high specific bactericidal activity in the blood. Severe leptomeningitis is a putative sequela of such an endocarditis.
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Lower extremity mycotic aneurysm in a patient with Listeria monocytogenes – associated prosthetic valve endocarditis
More LessIntroduction. Listeria monocytogenes is a rare etiology of infectious endocarditis with only 30 cases of prosthetic valve and about twice as many native valve infections described in the literature. We describe an unusual presentation of an endovascular embolic phenomenon with associated lower extremity mycotic aneurysm due to Listeria monocytogenes prosthetic aortic valve and aortic endograft infection.
Case presentation. This is a case of an elderly gentleman with prior history of bioprosthetic aortic valve placement and aortic arch repair who was admitted with several weeks of constitutional symptoms and left lower leg pain. Diagnostic work-up was consistent with thrombosed popliteal artery aneurysm. Blood cultures were positive for Listeria monocytogenes. A transesophageal echocardiogram revealed vegetation on the bioprosthetic valve. The patient underwent arterial bypass and ligation of the aneurysm as well as redoing of his aortic valve and aortic graft replacement. Histopathology of the aortic valve was remarkable for acute inflammation and Gram-positive coccobacilli and bacilli occupying intracellular spaces. The results of broad-range bacterial 16S rRNA PCR and sequence analysis of unfixed aortic valve tissue confirmed detection of L. monocytogenes.
Conclusion. Infective endocarditis attributable to species of the genus Listeriais a rare entity. As such, there are no specific guidelines for treatment of Listeria monocytogenesendocarditis. However, combination of penicillin or ampicillin with gentamicin is the most acceptable approach described in the literature. Our patient was treated with ampicillin and gentamicin for 6 weeks followed by life-long amoxicillin suppression therapy. The patient remained asymptomatic at a 6 months follow up visit.
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- Occular
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Aeromonas species endogenous endophthalmitis
More LessIntroduction. Aeromonas spp. are Gram-negative bacteria classically associated with water sources and a variety of clinical infections in humans.
Case presentation. A 79-year-old female patient presented with gastroenteritis with associated Aeromonas spp. bloodstream infection. Two days after admission she developed eye symptoms and was diagnosed with endophthalmitis and underwent emergency evisceration and implant. Aeromonas spp. was also recovered from intra-ocular samples.
Conclusion. In this case gastroenteritis caused by Aeromonas spp. was complicated by bloodstream infection which seeded to the eye, resulting in rapidly progressive endogenous endophthalmitis.
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- Soft Tissue
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A case of Vibrio vulnificus infection complicated with fulminant purpura: gene and biotype analysis of the pathogen
Introduction. Vibrio vulnificus (V. vulnificus) causes a severe infection that develops in the compromised host. Its pathophysiology is classified into three types: (1) primary septicaemia, (2) gastrointestinal illness pattern and (3) wound infection pattern. Of these, primary septicaemia is critical. V. vulnificus can be classified into three biotypes and two genotypes and its pathogenicity is type-dependent.
Case presentation. A 47-year-old man presented to a local hospital with chief complaints of fever, bilateral lower limb pain and diarrhoea. He had no history of foreign travel or known medical problems. He was in septic shock and developed fulminant purpura within 24 h of the onset. High-dose vasopressor and antibiotic administration failed to alter his status and he died 3 days after the onset of symptoms. V. vulnificus was isolated from blood, skin and nasal discharge cultures. Biotype and gene analysis of the microbe isolated identified it as Biotype 3, mainly reported in Israel in wound infections, and Genotype E, implicating an environmental isolate. These typing analyses indicated that the microbe isolated could be classified as a type with low pathogenicity.
Conclusion. This case highlighted that Biotype 3 and Genotype E can also cause primary septicaemia. Although the majority of reports on Biotype 3 have been from the Middle East, this experience with the present case provided evidence that the habitat of Biotype 3 V. vulnificus has been extending to East Asia as well.
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