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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.
Catheter-Associated Urinary Tract Infection
Published in Stephen M. Cohn, Alan Lisbon, Stephen Heard, 50 Landmark Papers, 2021
Emily M. Ramasra, Richard T. Ellison
The pathogenesis of CAUTI relates to colonization of the foreign catheter material and the bladder. Microorganisms form biofilms over the catheter, allowing them to persist with limited susceptibility to antibiotics or host defenses. The organisms that contribute to these infections include colonizers of the genital region and gastrointestinal tract. Alternatively, they can also be introduced from within the health care setting [7]. According to the CDC, the most common pathogens involved in catheter-associated bacteriuria (combining both symptomatic and asymptomatic) in hospitals reporting to the National Healthcare Safety Network (NHSN) between 2006 and 2007 were Escherichia coli (21.4%), Candida spp (21.0%), Enterococcus spp (14.9%), Pseudomonas aeruginosa (10.0%), Klebsiella pneumoniae (7.7%), and Enterobacter spp (4.1%). Gram-negative bacteria and Staphylococcus spp were the infecting bacteria in a smaller percentage of cases [8].
Preservatives and Preservation
Published in Philip A. Geis, Cosmetic Microbiology, 2020
For both manufacturing and consumer-derived contamination, Gram-negative bacteria provide the greatest risk due to their ubiquitous presence in aqueous environments (14,25,26) and propensity to adapt and grow in products and develop preservative resistance (15,27).
Effect of different dialysis duration on the prognosis of peritoneal dialysis-associated peritonitis: a single-center, retrospective study
Published in Renal Failure, 2023
Qichen Liang, Huiping Zhao, Bei Wu, Qingyu Niu, Lixia Lu, Jie Qiao, Chuncui Men, Yuting He, Xinxin Chu, Li Zuo, Mei Wang
Once the diagnostic investigations have been completed, empirical antibiotics should be started. Empirical antibiotic therapy must act on both gram-positive and gram-negative bacteria. According to the drug susceptibility results of causative organisms from our center, the initial empirical treatment included a combination of a first-generation cephalosporin and a third-generation cephalosporin administered intraperitoneally as an intermittent dose: ceftazidime and cefazolin 1.0 g, respectively, were added to 2 L peritoneal dialysate once a day, dwelling for at least 6 h. We use vancomycin for gram-positive bacteria in patients allergic to first-generation cephalosporins. On the 3rd day and the 5th day, cell counts were performed to observe the therapeutic effect. Once the bacterial culture results were reported, sensitive antibiotics were selected according to the drug susceptibility results. If peritonitis was not controlled after appropriate antibiotic treatment for 5 days, refractory peritonitis was diagnosed. For refractory or fungal peritonitis, catheters should be removed in time.
Tachyplesin I and its derivatives: A pharmaco-chemical perspective on their antimicrobial and antitumor potential
Published in Expert Opinion on Drug Discovery, 2022
Shengxin Lu, Jiayi Lin, Jinmei Jin, Lijun Zhang, Yingyun Guan, Hongzhuan Chen, Ye Wu, Weidong Zhang, Xin Luan
Further study of Hong et al. exhibited that TPI had another mechanism of action on the membrane [17]. Using scanning electron microscopy and transmission electron microscopy to observe the dynamic interaction between TPI and bacteria, they found that the membrane of both E. coli and S. aureus suffered varying degrees of damage over time, confirming that the main target for killing bacteria by TPI remains the membranes. However, it is worth noting that E. coli and S. aureus showed different modes of action upon TPI treated. The pore formation of bacterial cell wall and membrane and the efflux of contents inside could only be observed in E. coli, and TPI could accumulate in the cytoplasm of S. aureus without membrane destruction. These results indicated that TPI possessed different mechanism of action on diverse bacterial species. The biggest difference between Gram-positive bacteria and Gram-negative bacteria is the existence of outer membrane (Table 1). Gram-positive bacteria do not have the outer membrane but instead have a thick layer of peptidoglycan, whose main function is to protect cells from the external environment. In contrast, the outer membrane of Gram-negative bacteria is an asymmetric phospholipid bilayer, the inner leaflet is rich in phospholipid and outer leaflet is mainly composed of lipopolysaccharide [73]. Therefore, we speculate that the content of anionic components outside the different bacterial membranes determines the specific mechanisms of TPI.
Pars Plana Vitrectomy for Endophthalmitis: Microbiologic Spectrum and Clinical Outcomes
Published in Ocular Immunology and Inflammation, 2021
Chang Sup Lee, Miraj Khan, Jim Patrie, Asima Bajwa, Yevgeniy (Eugene) Shildkrot
Twenty-seven patients (84%) were culture-positive; 26 cases grew bacteria and 1 case showed Candida albicans (Table 1). Twenty-eight causative organisms were identified, as 1 patient had a polymicrobial infection (Table 2). Streptococcus species were the most common gram-positive organism. The most common gram-negative bacteria were Pseudomonas aeruginosa, Haemophilus influenza, and Moraxella species. Among the 19 patients who received vitreous tap prior to PPV, culture returned positive in 15 cases from the vitreous tap. Among these 15 culture-positive vitreous tap cases, only 3 cases showed positive culture on the samples obtained from PPV, which was performed after the vitreous tap and intravitreal antibiotics, indicating successful eradication of microbial infection. In contrast, the culture returned positive in 11 samples from 13 patients (84.6%) who did not receive vitreous tap or intravitreal antibiotics prior to PPV.