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Bacterial, Mycobacterial, and Spirochetal (Nonvenereal) Infections
Published in Ayşe Serap Karadağ, Lawrence Charles Parish, Jordan V. Wang, Roxburgh's Common Skin Diseases, 2022
Gram staining is a common technique used to differentiate two major groups of bacteria based on their cell wall properties. Gram-positive bacteria stain violet, while gram-negative bacteria stain pink or red. Gram-negative bacteria include Pseudomonas aeruginosa, Escherichia coli, Serratia marcescens, Klebsiella, and Proteus species.
Symptom flowcharts and testing guidelines
Published in Sarah Bekaert, Alison White, Integrated Contraceptive and Sexual Healthcare, 2018
Sarah Bekaert, Alison White, Kathy French, Kevin Miles
The Gram-staining process is a laboratory staining technique that distinguishes between two groups of bacteria by the identification of differences in the structure of their cell walls. The Gram stain, named after its developer, Danish bacteriologist Christian Gram, has become an important tool in bacterial taxonomy, distinguishing between so-called Gram-positive bacteria, which remain coloured after the staining procedure, and Gram-negative bacteria, which do not retain dye. The staining technique can be seen in the following table.
Sensitivity and specificity of the urine nitrite test and gram staining in diagnosing UTIs in children
Published in Cut Adeya Adella, Stem Cell Oncology, 2018
N. Fidelia, R. Ramayanti, S. Nafianti, Rusdidjas, O.R. Ramayani, R.S. Siregar, B. Siregar
The urine specimens were transported to the Microbiology Laboratory of H Adam Malik General Hospital within the hour. MacConkey agar was used for the urine culture. UTI was diagnosed with bacteriuria of > 105 CFU/ml. The gram staining was performed by one physician. The urine dipstick test (Verify Urinalysis) procedure was conducted.
Diagnostic performance of an in-house multiplex PCR assay and the retrospective surveillance of bacterial respiratory pathogens at a teaching hospital, Kelantan, Malaysia
Published in Pathogens and Global Health, 2023
Nik Mohd Noor Nik Zuraina, Suharni Mohamad, Habsah Hasan, Mohammed Dauda Goni, Siti Suraiya
Despite the good sensitivity and specificity, this assay had interpreted several discordant results compared to the gold standard methods, owing to the false positive amplifications. Among the false positive detections, six bacteria were from rejected specimens, comprising of K. pneumoniae and H. influenzae. Those specimens were found unsuitable for subsequent sputum culture due to disqualified scoring obtained from initial microscopic examination. A good quality sputum should have more than 25 neutrophil count and less than 10 epithelial cells per low-power field (10x objective) [15,16]. In this case, although sputum Gram-stain can detect as low as one bacterial cell per field, the multiplex PCR assay relatively seems more sensitive. A previous study reported that 90% (n = 37) of the rejected specimens had significant growth of pathogens on bacterial culture [17]. This shows that the Gram-staining might expose several limitations of the gold standard methods for the diagnosis of RTIs. As described by previous reports, the major drawbacks of Gram-staining include faulty smear separation, inadequate volume of sputum and irreproducible performance by different personnel [18,19]. In fact, sputum Gram-staining also has been reported with a wide variability of sensitivity and specificity (ranging from 11% to 100%) [20].
Evaluation of cytokine profile in cervicovaginal lavage specimens of women having asymptomatic reproductive tract infections
Published in Journal of Obstetrics and Gynaecology, 2022
Clara Aranha, Mayuri Goriwale, Shahina Begum, Sheetal Gawade, Vikrant Bhor, Anushree D. Patil, Kiran Munne, Vandana Bansal, Deepti Tandon
After heat fixing the smear, Gram staining was performed using commercially available stains. Gram-stained smears were examined under ×1000 magnification and information was recorded for Nugent’s score, presence of clue cells, pus cells/leukocytes along with detection of budding yeast cells. For cytokine analysis, cervicovaginal lavage was centrifuged at 1500 rpm for 10 min to settle down vaginal discharge and epithelial cells. Supernatant was filtered through 0.22 μm syringe filter (Axiva, Delhi, India) and aliquoted samples were stored at −80 °C. These supernatants were utilised for estimation of cytokines by ProcartaPlex multiplex immunoassays platform (Thermo Fisher, Waltham, MA) based on the principles of a sandwich ELISA and utilising Luminex xMAP (multianalyte profiling) technology. During batch testing, all the samples were thawed at room temperature and vortexed properly before use. IL-1β, IL-6, IL-8, IL-10, IL-12/IL23p40, IL-17A and TNF-α, interferon gamma (IFN-γ) were the eight cytokines analysed. All samples were tested in duplicate. The cytokine concentrations (pg/ml) in the unknown samples were derived from the premixed cytokine standards generated values (pg/ml). Reported cytokine concentrations were normalised against total protein concentration in cervicovaginal lavages (estimated by the Bradford method). Further normalised values were log-transformed to improve the normality of data distribution.
Clinical usefulness of multiplex PCR-lateral flow for the diagnosis of orthopedic-related infections
Published in Modern Rheumatology, 2019
Yojiro Minegishi, Katsufumi Uchiyama, Keizo Sakurai, Shiro Ibe, Hiromi Kanda, Shin Nihonyanagi, Masaki Nakamura, Shinsuke Ikeda, Masashi Takaso
The number of artificial joint implantation surgeries has steadily increased in recent years [1], and the number of patients with orthopedic-related infections is also expected to increase correspondingly. The gold standard for diagnosing orthopedic-related infections is bacterial culture. Unfortunately, it usually takes 2–3 days for the results of these cultures to be obtained, and the detection sensitivity is only about 60–70% [2,3]. Therefore, the diagnostic efficacy of bacterial cultures is limited, particularly for patients that need to start treatment immediately, such as those with acute periprosthetic joint infection (PJI) with sepsis or purulent arthritis. This and other orthopedic-related infections can be caused by a variety of bacterial species, with those caused by the methicillin-resistant Staphylococcus aureus (MRSA) being particularly difficult to treat [4]. Identifying the causative bacteria can increase the likelihood of successful treatment. Although Gram staining of the cultures can be used to evaluate the bacteria, it is difficult to determine pathogenic species with this method, which results in a high rate of treatment failures. Moreover, the successful detection rate of Gram staining is less than 1/3 [5,6]. Thus, as the prevalence of orthopedic-related infections increases, the development of a rapid and accurate diagnostic method is essential.