Viridans Streptococcus Bacteremia in Children on Chemotherapy for Cancer: An Underestimated Problem

Ahmed, Raija; Hassall, Tim; Morland, Bruce; Gray, James R.

doi:10.1080/08880010390220144

Cited by 59 publications

(40 citation statements)

References 8 publications

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“…Various risk factors for viridans streptococcal bacteremia have been identified and reviewed (11,23,28,29,32), including profound neutropenia, oral mucositis, prophylactic use of a fluoroquinolone or trimethoprim-sulfamethoxazole, exposure to high-dose chemotherapy (particularly cytosine arabinoside), stem cell transplantation, age of Ͻ18 years, and others. The importance of such bacteremia among pediatric patients with cancer has also been appreciated (1,17,26). The clinical findings from this study are consistent with these general features.…”

Section: Discussionsupporting

confidence: 81%

Viridans Streptococci Isolated by Culture from Blood of Cancer Patients: Clinical and Microbiologic Analysis of 50 Cases

2006

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Clinical and microbiologic studies of 50 cases of viridans streptococcal bacteremia in cancer patients were performed. The bacteria were identified to species level by sequencing analysis of the 16S rRNA gene. At least nine Streptococcus spp. were found, including S. mitis (25 strains, 50.0% of 50); currently unnamed Streptococcus spp. (11 strains); S. parasanguis (five strains); S. anginosus (three strains); S. salivarius (two strains); and one strain each of S. gordonii, S. sanguis, S. sobrinus, and S. vestibularis. There were no S. oralis strains. Among 11 antibiotics of nine classes tested, no resistance to vancomycin, linezolid, or quinupristin-dalfopristin was seen. Resistance to penicillin (MIC, 4 to 12 g/ml) was noted only among S. mitis strains (28.0%, 7/25) and not non-S. mitis strains (0/25) (P ‫؍‬ 0.004). Significantly more S. mitis strains than non-S. mitis strains were resistant to fluoroquinolones and to >3 classes of antibiotics. Isolation of quinolone-resistant organisms was associated with the prior usage of quinolones (P ‫؍‬ 0.002). Quantitative blood cultures showed that the strains resistant to levofloxacin or gatifloxacin were associated with higher colony counts than were their corresponding nonresistant strains. The young and elderly patients also had higher levels of bacteremia caused predominantly by S. mitis. Septic shock was present in 17 (34.0% of 50) patients, and 13 of those cases were caused by S. mitis (P ‫؍‬ 0.007). These results suggest that S. mitis is the most common cause of viridans streptococcal bacteremia in cancer patients and is more resistant to antibiotics than other species.Viridans streptococci represent a group of 24 currently described Streptococcus species that are nutritionally fastidious and mainly alpha-hemolytic on sheep blood agar (30). These gram-positive cocci are commensals of the oral cavity, upper airway, and gastrointestinal and genitourinary tracts. Despite the overall low virulence, they may cause infective endocarditis, contribute to polymicrobic abscess, and invade the bloodstream during the state of neutropenia.The bloodstream infection usually occurs in cancer patients with mucositis and neutropenia due to antineoplastic chemotherapy-related toxicity. In these patients, studies have found that viridans streptococci are among the most common organisms isolated from the cultures of bacteremia samples (17). As cancer care has improved and intensified over recent decades and the patients survive longer, these and other infectious complications become more pronounced. A study from our institution showed that the rate of viridans streptococcal bacteremia increased from 1 per 10,000 admissions to 47 per 10,000 during the 13-year period from 1977 to 1989 (11). These bacteremias cause substantial morbidity, and mortality in these patients is at 6 to 12% (17, 29).The most common viridans streptococci that cause neutropenic bacteremia have been S. oralis, S. mitis, and S. salivarius (4,11,15,17). Identification of these species, however, was reached through...

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Section: Discussionsupporting

confidence: 81%

Viridans Streptococci Isolated by Culture from Blood of Cancer Patients: Clinical and Microbiologic Analysis of 50 Cases

2006

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“…In Europe, S. salivarius belongs to risk group 2 (like S. pyogenes or S. pneumoniae), while the very closely related Streptococcus species S. thermophilus, S. uberis, and S. vestibularis (32) belong to risk group 1. Presumably, S. salivarius is considered an opportunistic pathogen because, as with many food-grade lactobacilli, there have been sporadic reports of infections, generally in subjects under adverse medical conditions (2,3,10). Quite the opposite, in other parts of the world, S. salivarius has already acquired the status of safe microorganism and has been commercialized for several years as a probiotic without any re- (9).…”

Section: Discussionmentioning

confidence: 99%

Oral Bacteria as Potential Probiotics for the Pharyngeal Mucosa

Guglielmetti¹,

Taverniti²,

Minuzzo

et al. 2010

Appl Environ Microbiol

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The research described here was aimed at the selection of oral bacteria that displayed properties compatible with their potential use as probiotics for the pharyngeal mucosa. We included in the study 56 bacteria newly isolated from the pharynges of healthy donors, which were identified at the intraspecies level and characterized in vitro for their probiotic potential. The experiments led us to select two potential probiotic bacterial strains (Streptococcus salivarius RS1 and ST3) and to compare them with the prototype oral probiotic S. salivarius strain K12. All three strains efficiently bound to FaDu human epithelial pharyngeal cells and thereby antagonized Streptococcus pyogenes adhesion and growth. All were sensitive to a variety of antibiotics routinely used for the control of upper respiratory tract infections. Immunological in vitro testing on a FaDu layer revealed different responses to RS1, ST3, and K12. RS1 and ST3 modulated NF-B activation and biased proinflammatory cytokines at baseline and after interleukin-1␤ (IL-1␤) induction. In conclusion, we suggest that the selected commensal streptococci represent potential pharyngeal probiotic candidates. They could display a good degree of adaptation to the host and possess potential immunomodulatory and anti-inflammatory properties.Metagenomics and functional molecular immunology substantiate the interpretation of humans as holobionts, in the sense of functional superorganisms, combining the self and microbes acting in concert to produce phenomena governed by the collective (25,42). The association between host and symbionts affects the fitness of the holobiont within its environment, and it often governs the physiological homeostasis of the narrow balance between host well being and dysfunction (13,35).The mechanisms underlying the cross talk between a human host and microbes are only marginally understood. Their elucidation at a molecular level could supply the theoretical bases to develop strategies for preventing or treating several human dysfunctions, such as autoimmune diseases, through the reconstitution of a proper human-microbe mutualism.The probiotic approach, in its widest sense, falls into this context, since it consists of the modification of a human microbiota by exogenous administration of microbial cells (or cell components), aimed at benefiting the host's health. A most commonly accepted definition comes from FAO/WHO, which states that probiotics are "live microorganisms which when administered in adequate amounts confer a health benefit on the host" (17).So far, probiotics have been most predominantly investigated for and applied to the intestinal tract. Nevertheless, a few applications beyond the gut have proposed the potential beneficial role of probiotics for the stomach (23), vaginal mucosa (36), urinary tract (6), skin (27), and oral cavity (39). With respect to oral probiotics, particularly noticeable are the studies done by J. R. Tagg and coworkers of Streptococcus salivarius strain K12. Tagg and others, in fact, showed that, follow...

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“…Streptococcus salivarius is known to be a pioneer colonizer of infants, who typically acquire it from their mothers shortly after birth (7,10,19). As with lactobacilli, there have been occasional reports of infections involving S. salivarius, though their occurrence (even in adverse medical conditions) is extremely low (1,2,6,8,16,20,23).…”

mentioning

confidence: 99%

Safety Assessment of the Oral Cavity Probiotic Streptococcus salivarius K12

Burton

Wescombe²,

Moore³

et al. 2006

Appl Environ Microbiol

151

101

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Streptococcus salivarius is a prominent member of the oral microbiota and has excellent potential for use as a probiotic targeting the oral cavity. In this report we document safety data relating to S. salivarius K12, including assessment of its antibiogram, metabolic profiles, and virulence determinants, and we examine the microbial composition of saliva following the dosing of subjects with K12.

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Viridans Streptococcus Bacteremia in Children on Chemotherapy for Cancer: An Underestimated Problem

Cited by 59 publications

References 8 publications

Viridans Streptococci Isolated by Culture from Blood of Cancer Patients: Clinical and Microbiologic Analysis of 50 Cases

Viridans Streptococci Isolated by Culture from Blood of Cancer Patients: Clinical and Microbiologic Analysis of 50 Cases

Oral Bacteria as Potential Probiotics for the Pharyngeal Mucosa

Safety Assessment of the Oral Cavity Probiotic Streptococcus salivarius K12

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