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Pathogenicity and Virulence
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
A few pathogens such as Coxiella burnetii and certain Leishmania spp. are fully capable of surviving within phagolysosomes. Acid fast organisms such as Mycobacteria and pathogenic Nocardia spp. are also very resistant to enzymatic damage because of their lipid-rich cell walls.
Understanding Microbiology Culture Results
Published in Firza Alexander Gronthoud, Practical Clinical Microbiology and Infectious Diseases, 2020
Mycobacteria can be detected using a Ziehl–Neelsen stain or a fluorescent auramine stain. Mycobacteria have a waxy mycolic acid in their cell wall which resists a Gram stain. A Ziehl–Neelsen stain was developed whereby carbol fuchsin is used as the initial stain and heat is applied to fixate the carbol fuchsin into the cell wall. Because of mycolic acid in their cell wall, the acid alcohol used in the decolourization is not able to remove carbol fuchsin from the cell wall, and consequently, they appear bright red. This is why mycobacteria are also called acid-fast bacilli. A sputum sample needs to contain at least 104 mycobacteria per millilitre before they can be detected with microscopy.
Infectious and parasitic causes of hypopigmentation
Published in Electra Nicolaidou, Clio Dessinioti, Andreas D. Katsambas, Hypopigmentation, 2019
Serena Gianfaldoni, Aleksandra Vojvodic, Nooshin Bagherani, Bruce R. Smoller, Balachandra Ankad, Leon Gilad, Arieh Ingber, Fabrizio Guarneri, Uwe Wollina, Torello Lotti
Leprosy is caused by an intracellular bacterium called Mycobacterium leprae (M. leprae), a weakly acid-fast bacillus (AFB). It is contagious; however, the exact mechanism of transmission is not known. It is believed to spread via droplets from the nose or mouth or rarely by direct skin contact with lesions of infected individuals.23–25 Among people exposed to M. leprae, 95% are not susceptible to infection, while among the 5% who become infected, only 1% shows the disease. Hence, it appears that hosts’ genetic predisposition and impaired immune system play a critical role in disease development.26,27
Tuberculous peritonitis in patients on peritoneal dialysis: a 35-year experience from a large medical center in Northern Taiwan
Published in Renal Failure, 2023
Tzu-Yi Yang, Ya-Chung Tian, Tzung-Hai Yen, Ming-Yang Chang, Chan-Yu Lin, Shou-Hsuan Liu
In our retrospective cohort study, we initially reviewed 2084 PD patients at Linkou CGMH over a period of 35 years (from January 1985 to December 2019). Peritonitis was diagnosed when the patient met at least two out of the following three characteristics: (1) consistent clinical features, including abdominal pain or cloudy effluent, (2) peritoneal fluid white blood cell (WBC) count greater than 100/mm3 (or 0.1 x 109/L after a dwell time of at least two hours), with > 50% neutrophils, and (3) positive dialysis effluent culture [20]. In terms of TB infection detection, we adopted acid fast stain (AFS) smear, polymerase chain reaction (PCR) and culture for Mycobacterium tuberculosis (MTB). The definite diagnosis of TBP in our study was established only by positive peritoneal fluid culture for MTB.
The gut microbiota mediates protective immunity against tuberculosis via modulation of lncRNA
Published in Gut Microbes, 2022
Fang Yang, Yi Yang, Lingming Chen, Zhiyi Zhang, Linna Liu, Chunmin Zhang, Qiongdan Mai, Yiwei Chen, Zixu Chen, Tao Lin, Liang Chen, Huixin Guo, Lin Zhou, Hongbo Shen, Xinchun Chen, Lei Liu, Guoliang Zhang, Hongying Liao, Lingchan Zeng, Gucheng Zeng
Histopathological, bacterial and immune analyses of M. tuberculosis-infected mice: At the end of the M. tuberculosis infection period, animals were sacrificed. The right lung and cecum were excised and carefully homogenized. For H&E and acid-fast Kinyoun’s analysis, lung or gut tissues of mice were fixed in 10% formalin and processed for paraffin embedding. Paraffin sections of 5 µm were counterstained with H&E or Kinyoun’s. Images of acid-fast staining were obtained using a microscope (Olympus BX63). H&E staining was taken by Digital Slide Scanning System AxioScan.Z1. All sections were interpreted by the same person and scored semiquantitatively, blinded to the variables of the experiment. The histopathological parameters inflammatory lesions and granuloma formation were scored as our previous study.14
Evaluation of the performance of the BD MAX MDR-TB test in the diagnosis of Mycobacterium tuberculosis complex in extrapulmonary and pulmonary samples
Published in Expert Review of Molecular Diagnostics, 2021
Pınar Sağıroğlu, Mustafa Altay Atalay
Acid-fast bacteria (AFB) were studied with the Ziehl-Neelsen (ZN) staining method simultaneously in all samples included in the study. Mycobacterial cultures of samples were made in BACTEC MGIT 960 liquid culture (Becton Dickinson, USA) system and Lowenstein-Jensen (LJ) (RTA, Turkey) medium. The sodium hydroxide-N-acetyl-L-cysteine decontamination process was used for all specimens except cerebrospinal fluid (CSF), and then 200 µL of each sample was inoculated into LJ medium and 0.5-mL into MGIT tube and incubated. Liquid cultures were followed on the instrument for 42 days, solid cultures for 60 days. BD MGIT TBc ID Test (Becton Dickinson, USA), which detects MPT64 protein, was used to identify isolated strains. Strains positive with the TBc ID test were defined as MTC, and those with negative test results were defined as non-tuberculous mycobacteria (NTM). Antibiotic susceptibility tests of MTC strains against primary drugs (Isoniazid, rifampicin, streptomycin, and ethambutol) were performed using BD MGIT™-AST SIRE Test Kit (Becton Dickinson, USA).