Clindamycin
Thomas T. Yoshikawa, Shobita Rajagopalan in Antibiotic Therapy for Geriatric Patients, 2005
Clindamycin has excellent activity against a variety of gram-positive and obligate anaerobic bacteria (Table 1). Most streptococci, including β-hemolytic Streptococcus spp. and Streptococcus pneumoniae, are susceptible to clindamycin. In a recent study of the antibiotic susceptibility profile among β-hemolytic streptococci collected in the SENTRY Antimicrobial Surveillance Program across North America (1), all Lancefield group C and F Streptococcus isolates were uniformly susceptible to clindamycin. Resistance was only rarely detected among Lancefield group A and G isolates (0.8-2.2%), but the rate was higher for group B Streptococcus isolates (11.4%). In a nationwide survey of 1531 S. pneumoniae isolates, more than 90% were susceptible to clindamycin (2). However, the rate of clindamycin resistance was much higher among penicillin-intermediate and penicillin-resistant S. pneumoniae isolates compared to penicillin-susceptible isolates (20.1% and 26.1% vs. 1.5%, respectively). Viridans streptococci are generally susceptible to clindamycin.
Streptococcus mitis
Peter M. Lydyard, Michael F. Cole, John Holton, William L. Irving, Nino Porakishvili, Pradhib Venkatesan, Katherine N. Ward in Case Studies in Infectious Disease, 2010
During colonization of the oropharynx at birth protection is initially mediated by the mucous membranes acting as barriers and the large number of innate immune factors present in saliva (see Further Reading: Cole & Lydyard, 2006). Secretory IgA antibodies secreted at low concentrations from birth are effective barriers to the penetration of S. mitis. Host phagocytes are a second line of defense against streptococcal invasion. Streptococci are opsonized by activation of the alternative and lectin innate complement pathways and the classical pathway in the presence of IgM and IgG antibodies in the plasma and tissue fluid. Viridans streptococci entering the bloodstream are attracted to damaged endocardium or endothelial tissue. The streptococci commonly adhere to congenitally malformed or prosthetic heart valves, with the mitral valve usually the most commonly affected. However, the bacteria may colonize a septal defect or attach to other areas of the heart. The bacteria form a vegetation (an accumulation of bacteria, platelets, and fibrin). Alternatively, streptococci in the blood can adhere to thrombi, leading to increased platelet and fibrin deposition, such that these vegetations grow by accretions of layers of fibrin and platelets with bacterial colonies sandwiched between them. These vegetations are friable (fragile, crumbly) and portions may detach forming emboli that may seed many organs including spleen, kidneys, bowel, or brain, causing infection and infarction.
Practice Paper 9: Answers
Anthony B. Starr, Hiruni Jayasena, David Capewell, Saran Shantikumar in Get ahead! Medicine, 2016
Viridans streptococci are a large group of bacterial organisms that are usually commensals in the oral cavity. They are the most common cause of bacterial endocarditis, being responsible for approximately 60% of cases. Individuals with pre-existing valvular disease are at risk of viridans streptococcal endocarditis following invasive dental procedures such as tooth extraction. Antibiotic treatment is usually with intravenous benzylpenicillin, with the addition of gentamicin if resistant bacteria are present. Patients with known valvular heart disease should always receive prophylactic antibiotics prior to any invasive procedure.
16S rRNA is a valuable tool in finding bacterial aetiology of community-acquired pleural empyema–a population-based observational study in South Sweden
Published in Infectious Diseases, 2022
Jakob Hjertman, Jonas Bläckberg, Oskar Ljungquist
In total, 291 patients were included in the study with 429 pleural samples. The median age was 69 years and 63% (n = 184) were men. For the majority, 105 patients (36%), the bacterial aetiology was viridans streptococci, out of which 80% was Streptococcus anginosus. S. pneumoniae were found in samples of 42 patients (14%). Anaerobic bacteria were seen in 34 patients (12%), of which Fusobacterium nucleatum were most commonly found (n = 12). For 26 patients (9%), a combination of viridans streptococci and anaerobic bacteria were found. S. aureus or Enterobacterales were found in a minority of pleural samples, 20 patients (6.9%) and 14 patients (4.8%), respectively. A minimum of 2 bacteria were found in 61 patients (21%). A detailed list of bacterial aetiology is presented in Table 1.
Reducing infectious complications after allogeneic stem cell transplant
Published in Expert Review of Hematology, 2020
Andrea Bacigalupo, Elisabetta Metafuni, Viviana Amato, Ester Marquez Algaba, Livio Pagano
BSI are reported to occur in 25–45% of HSCT recipients [18,19]. In a recent study performed at the Hospital Clinic in Barcelona, changes in BSI epidemiology were collected during a 25 years period (from 1993 to 2017). Catheter-related BSI accounted for 45.1% of cases and endogenous/unknown sources for an other 39.6% [20]. Several variations may occur between different centers and among patients, due to different transplantation platforms, with different stem cell sources, conditioning regimens and GvHD prophylaxis [21]. In the pre-engraftment period, both Gram-negative and Gram-positive BSI can occur, while in the late phase, encapsulated pathogens are more frequent (Haemophilus influenzae and Streptococcus pneumoniae) [16]. Commonly, oral mucositis facilitates infections due to viridans Streptococci and Coagulase-negative Staphylococci, whereas enteric mucositis promotes infections caused by Enterobacteriaceae, Enterococci and Pseudomonas aeruginosa. Central venous catheters represents an additional risk factor [21].
Etiology, drug sensitivity profiles and clinical outcome of bloodstream infections: A retrospective study of 784 pediatric patients with hematological and neoplastic diseases
Published in Pediatric Hematology and Oncology, 2019
Senmin Chen, Sixi Liu, Xiuli Yuan, Huirong Mai, Junrong Lin, Feiqiu Wen
Resistance patterns of CoNS, K. pneumoniae, E. coli, viridans streptococci, S. aureus, Acinetobacter baumannii, and Pseudomonas in patients are summarized in Table 2. The response rates of the Gram-negative bacteria to piperacillin/tazobactam, imipenem, meropenem, and amikacin were high. E. coli showed higher levels of beta-lactam and 4-fluoro-quinolone resistance compared to K. pneumoniae. Low levels of antibiotic resistance were observed in Pseudomonas aeruginosa. All Gram-positive bacteria were susceptible to vancomycin, which was empirically added to the antibiotic therapy in patients with persistent fever. CoNS were often resistant to a variety of antibiotics, including penicillin, amoxicillin, erythromycin, azithromycin, and cotrimoxazole, but was only relatively sensitive to gentamicin, rifampicin, and levofloxacin. Viridans streptococci showed high levels of resistance to macrolides.
Related Knowledge Centers
- Agar Plate
- Commensalism
- Optochin
- Streptococcus Pneumoniae
- Streptococcus
- Hemolysis
- Pathogen
- Antigen
- Gram-Positive Bacteria
- Lancefield Grouping