Biology of microbes
Philip A. Geis in Cosmetic Microbiology, 2006
When cultured on blood agar, S. aureus produces a clear zone known as β-hemolysis caused by the production of a toxin that lyses red blood cells. The role of the hemolysin in disease is not entirely known. The staphylococci also produce a variety of enzymes such as hyaluronidase, proteinases, lipases, coagulase, and penicillinase. The production of coagulase can be used to confirm in the laboratory that an organism is S. aureus, a potential pathogen. When S. aureus produces coagulase, it clots the serum. Performing this test in a laboratory is relatively simple: the addition of a culture to human or rabbit plasma in a tube; after a brief incubation, the coagulase-positive S. aureus clots the plasma through the formation of a fibrin clot. Its presence in a cosmetic indicates human contamination.
An Overview of Microbes Pathogenic for Humans
Nancy Khardori in Bench to Bedside, 2018
Staphylococcus aureus is the most virulent and best studied species of this genus. According to the National Healthcare Safety Network data, S. aureus was the most frequently reported pathogen in healthcare- associated infections in 2009 and 2010 (Sievert et al. 2013). One of the defining features of this bacterium is its ability to produce the enzyme coagulase, which is capable of converting fibrinogen to fibrin. Therefore, a coagulase test is often utilized to differentiate S. aureus from other members of the Staphylococcus genus. Additionally, coagulase acts as a virulence factor by blocking phagocytosis by immune cells (Fry 2013). Many of the other pathogenic/opportunistic members of this genus are often referred to as “coagulase negative staphylococci”.
Host-Parasite Relationships
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
The second most abundant group of bacteria on the skin are Gram-positive cocci. Many of these cocci resemble the pathogenic Staphylococcus aureus, but differ in that they do not produce coagulase. Coagulase production is a distinguishing feature used to differentiate pathogenic from nonpathogenic staphylococci. The various commensal micrococci and staphylococci that are present probably prevent colonization of the skin by other potentially pathogenic Gram-positive bacteria. The non-pathogenic Gram-positive cocci normally present on the skin are often collectively called Staphylococcus epidermidis. The Gram stain reaction and other attributes of bacteria are described in chapter 15. The pathogenic S. aureus frequently colonizes the nose and perianal region of healthy people. When this occurs in doctors, nurses, and other health personnel, they may infect patients with whom they have contact.
Evaluation of fosfomycin combined with vancomycin against vancomycin-resistant coagulase negative staphylococci
Published in Journal of Chemotherapy, 2020
Yasser Musa Ibrahim, Wael Mohamed Abu El-Wafa
Selected CoNS isolates were identified to the species level based on their biochemical characteristics. We adopted two identification schemes; Cowan and Steel’s28 and Sah et al.5 The latter scheme was validated by molecular methods involving PCR and sequencing and proved to accurately identify S. epidermidis and other CoNS isolated from clinical materials.5 The identification tests included the fermentation of lactose, maltose, mannitol, mannose, sucrose and trehalose as well as novobiocin sensitivity testing. Production of coagulase and oxidase and haemolytic activity were also tested. All sugar utilization tests were carried out on phenol red broth as described by Sah et al.5 Oxidase test was performed using commercially available oxidase discs (Himedia) according to manufacturer’s recommendations. Haemolytic activity was tested on blood agar base (oxoid) supplemented with 5% of sheep blood.29
Characterization, epidemiological profile and risk factors for clinical outcome of infective endocarditis from a tertiary care centre in Turkey
Published in Infectious Diseases, 2019
Hicaz Zencirkiran Agus, Serkan Kahraman, Cagdas Arslan, Gamze Babur Guler, Ali Kemal Kalkan, Cafer Panc, Fatih Uzun, Mehmet Erturk, Mustafa Yildiz
We conducted a retrospective cohort study to describe the epidemiological, demographic and clinical characteristics of IE and to identify factors associated with in-hospital mortality in patients admitted to a tertiary care hospital in Turkey. The median age of our patients was 58 (43–66) similarly to reports of developed countries [10,11]. Studies from developing countries reported that patients with IE to be mostly young due to incidence of RHD [12–14]. In a study by Leblebicioğlu et al., the mean age for IE was 45 years [15]. In previous studies in Turkey, the average age was lower [16]. Our study mainly demonstrated that coagulase negative staphylococci were the most common pathogen. Prosthetic valve disease was the most frequent predisposing valve lesion and most commonly affected valve was the mitral valve. However, we also found that age, perforated valve, septic shock and syncope were independent predictors of in-hospital mortality.
Management of febrile neutropenia in the perspective of antimicrobial de-escalation and discontinuation
Published in Expert Review of Anti-infective Therapy, 2019
Martin Schmidt-Hieber, Daniel Teschner, Georg Maschmeyer, Enrico Schalk
CVC-related BSI is mainly caused by Gram-positive bacteria, most commonly coagulase-negative Staphylococcus spp., but also S. aureus, Streptococcus spp., and Enterococcus spp., respectively. Follow-up blood cultures might be taken every 48 h in patients with persistent FN to detect also pathogens that are not easy to culture or that are not covered by preemptive antibiotic therapy. However, the expected yield to detect relevant causative pathogens by follow-up blood cultures is low [32]. Immediate CVC removal is mandatory especially for CVC-related infections caused by S. aureus and Candida spp. or in case of sepsis (with or without the presence of neutropenia) (Figure 2). Taking into account the comparable low pathogenicity of coagulase-negative Staphylococcus spp., CVC-related BSI by these pathogens should commonly be treated only for 5 to 7 days [110]. However, at least 2 weeks of appropriate antimicrobial treatment is recommended for S. aureus or Candida spp. BSI, depending on the growth of pathogens in repeated blood cultures [111,112].
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