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Host-Parasite Relationships
Published in Julius P. Kreier, 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.
Factors Controlling the Microflora of the Healthy Upper Gastrointestinal Tract
Published in Michael J. Hill, Philip D. Marsh, Human Microbial Ecology, 2020
A major factor controlling the bacterial microflora of the intestinal tract is the oxygen tension which is related to the redox conditions. Numerous species of bacteria have a nominal strict requirement for oxygen but such organisms are able to proliferate if an alternative hydrogen acceptor is available. Thus, Pseudomonas spp., Micrococcus spp., and Neisseria spp. are able to grow under anoxic conditions in the presence of nitrate or nitrite. The upper gastrointestinal tract is rarely anoxic (except, perhaps, in the lower ileum) while nitrate and nitrite are present in the stomach and upper small intestine. Thus, if the conditions of pH permit, the conditions of oxygen tension and hydrogen acceptor status will be favorable to the growth of the strictly aerobic species. As is discussed later, pseudomonads, micrococci, and neisseria are regularly reported to be present in the microflora of the gastrointestinal tract. In contrast to the strictly aerobic organisms, the strictly anaerobic genera are unable to survive long periods of exposure to even small concentrations of oxygen and flourish optimally when the redox potential is very low. However, in all parts of the digestive tract there are micro-habitats where the presence of oxygen-utilizing bacteria lowers the oxygen tension and the redox potential to a level that permits the growth of even the most fastidiously oxygen-sensitive genera of bacteria.
Microbial Biofilms
Published in Chaminda Jayampath Seneviratne, Microbial Biofilms, 2017
Chaminda Jayampath Seneviratne, Neha Srivastava, Intekhab Islam, Kelvin Foong and Finbarr Allen
Dental chair units have a complex network of interconnected waterline systems to cool and irrigate instruments and tooth surfaces and provide rinse water during various dental treatment procedures [124]. Dental units, particularly the waterline tubes that supply water to the dental instruments, inevitably harbour a wide variety of microorganisms including bacteria, fungi and protozoans. The microorganisms adhering to the waterlines inevitably lead to biofilm formation on these surfaces. However, dental water unit biofilms are not harmful unless colonised with pathogenic bacteria or exceeding certain microbiological levels [40]. Current CDC guidelines for infection control in dental healthcare settings recommend that output water from dental units should not exceed 500 colony-forming units (CFU)/mL of aerobic heterotrophic bacteria [124]. Hence, mostly saprophites, such as Moraxella spp., Flavobacterium spp., Micrococcus spp. and Actinomyces spp. and yeast species can be present in the dental waterline output in harmless concentrations. Under certain circumstances, pathogenic species such as P. aeruginosa, Legionella spp. and Mycobacteria spp. have also been isolated from these biofilms [125]. A further concern of colonised dental unit waterlines is the potential for cross-contamination of patients with infectious microorganisms Therefore, if proper infection control of dental units is not followed, it can be a serious source of cross-contamination.
Bacterial communities in bovine ejaculates and their impact on the semen quality
Published in Systems Biology in Reproductive Medicine, 2021
Michal Ďuračka, Ljubica Belić, Katarína Tokárová, Jana Žiarovská, Miroslava Kačániová, Norbert Lukáč, Eva Tvrdá
The present study describes the bacterial profile of bovine semen and its implication on the resulting sperm quality. As described previously in Andrabi et al.’s (2016) report, staphylococci, Escherichia coli and Pseudomonas aeruginosa were identified as the predominant representatives of bacteriocenoses in fresh bovine ejaculates. The bacterial load in fresh bovine semen was determined to be 4.31 log10 CFU/mL in the above-mentioned study, which is similar to our data (4.85 log10 CFU/mL). Moreover, the presence of Staphylococcus spp., Micrococcus spp., Escherichia coli, Pseudomonas spp., Corynebacterium spp., Proteus spp., Klebsiella spp. and Bacillus spp. was reported in frozen semen (Mitra et al. 2016). Samples containing these bacteria were associated with a reproduction failure following insemination. The presence of bacterial species identified in the EX, GO, and MO groups is, however, not uncommon when compared with previously published studies (González-Marín et al. 2011; Dotis et al. 2015; Andrabi et al. 2016). The most uniform bacterial representation was observed in the GO community, in which B. cereus was the most frequently represented without any negative effects previously reported on spermatozoa. However, S. aureus was the most abundant bacteria in the MO group, which is considered a serious uropathogen able to significantly decrease the sperm motility and viability in vitro (Liu et al. 2002).
Does intraoperative contamination during primary knee arthroplasty affect patient-reported outcomes for patients who are uninfected 1 year after surgery? A prospective cohort study of 714 patients
Published in Acta Orthopaedica, 2020
Tobias Justesen, Jakob B Olsen, Anne B Hesselvig, Anne Mørup-Petersen, Anders Odgaard
At the start of analyzing data for this study May 2019, 1,499 patients were included in either the SPARK study, the ICON study, or both studies (Figure 2). 766 patients were only included in either the ICON or SPARK study due to different enrollment centers and enrollment periods and were thus excluded. 19 patients were excluded due to PJIs or revision surgery. 2 of the 12 patients excluded due to PJIs were intraoperatively contaminated. 1 patient was contaminated with Micrococcus species while joint fluid and biopsy at revision surgery showed Streptococcus dysgalactiae. The other patient was contaminated with Staphylococcus capitis and epidermidis, and joint fluid and biopsy at revision surgery revealed Staphylococcus epidermidis. None of the 7 patients who underwent revision surgery, for reasons other than PJIs, were intraoperatively contaminated. Furthermore, none of the intraoperative biopsies from the revisions, which were done on 4 of the patients on the slightest suspicion of infection, revealed any positive culture. The reasons for revision surgery were: rupture of the posterior cruciate ligament, medial tibial plateau fracture, instability, loosening of the prosthesis, progression of arthrosis, and in 2 cases pain and instability. A sufficient PRO sequence and contamination data were available for 714 patients (389 women and 325 men), who were included in the final analysis.
Effect of a “handshake” stewardship program versus a formulary restriction policy on High-End antibiotic use, expenditure, antibiotic resistance, and patient outcome
Published in Journal of Chemotherapy, 2020
Rima Moghnieh, Lyn Awad, Dania Abdallah, Marwa Jadayel, Loubna Sinno, Hani Tamim, Tamima Jisr, Salam El-Hassan, Rawad Lakkis, Rima Dabbagh, Abdul Rahman Bizri
Bacteremia was defined as the isolation of at least one clinically relevant pathogen from one blood culture drawn from a patient with an indicative clinical syndrome. Organisms of the same species with the same antimicrobial susceptibility profile isolated from the same patient (matching hospital case number) were considered duplicate isolates and were removed from the analysis. Coagulase-negative staphylococci and other microorganisms that are generally considered contaminants, such as Corynebacterium spp., Bacillus spp., Micrococcus spp., and Propionibacterium spp., were also excluded from the analysis.23 The electronic medical records of patients with positive blood cultures were reviewed to assess whether the bacteremia was nosocomial. Nosocomial bacteremia was defined as the isolation of pathogenic bacteria from blood cultures taken 2 days and more after admission.23 We reviewed the monthly variation of the incidence rate of nosocomial bacteremia per 1000 PD before and after ASP. We specifically studied the monthly variation of the incidence rate of bacteremia caused by carbapenem-resistant Gram-negative bacteria (CRGNB), CRAB, and CRPA.