The viridans group streptococci (VGS), a heterogenous group of streptococcal species, are the predominant species of the human oral flora and commonly. Abstract. The frequency of isolation of viridans streptococci from the blood of neutropenic patients with cancer has significantly increased over the course of. Streptococcus viridans: human disease: Infectious agents: Streptococcus viridans bacteria, for example, are found in the throats of more than 90 percent of.
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The frequency of isolation of viridans streptococci from the blood of neutropenic patients with cancer has significantly increased over the course of the last estreptcoco years.
Viridans streptococci – Wikipedia
Risk factors in this patient population include severe neutropenia, oral mucositis, administration of high-dose cytosine arabinoside, and antimicrobial prophylaxis with either trimethoprim-sulfamethoxazole or a fluoroquinolone.
In some patients with cancer and neutropenia who develop viridans streptococcal bacteremia, a toxic shock—like syndrome has been described; Streptococcus mitis estreptocoo been the causative species in most cases. Because resistance of viridans streptococci to a variety of antimicrobial agents is increasingly recognized, penicillin susceptibility cannot be assumed, and empirical vancomycin therapy should be used ewtreptococo treat neutropenic patients with cancer who have shock or are developing acute respiratory distress syndrome.
Given the seriousness of septicemia caused by viridans streptococci and the potential for selection of other resistant microorganisms, the routine practice of antimicrobial prophylaxis for neutropenic patients with cancer should be reconsidered.
Over the course of the last several decades, the frequency with which gram-positive bacteria have been isolated from neutropenic patients with cancer has increased. Similar trends have also been documented in other centers. Gram-positive bacteria isolated have included Staphylococcus aureuscoagulase-negative staphylococci, and Enterococcus species. In addition, viridans streptococci have emerged as an important cause of bacteremia in neutropenic patients with cancer.
Viridans streptococci are part of the normal microbial flora of humans [ virifans ]. In the s, 2 schemes for identification of the viridans streptococci were proposed. Colman and Williams suggested classification into 5 species Streptococcus mutans, Streptococcus milleri, Streptococcus sanguis, Streptococcus salivariusand Streptococcus mitiorand the scheme of Facklam recognized 10 physiological species S.
More recently, a molecular approach has been used to define the taxonomy of the viridans streptococci on the basis of genetic relatedness table 1. The viridans streptococci are most prevalent in the oral cavity but also rstreptococo in the upper respiratory tract, the female genital tract, and all regions of the gastrointestinal tract; they also are occasionally found as part of the skin flora.
Although they are commensal organisms in these sites, these microorganisms may also invade sterile body sites, which can lead to life-threatening diseases e. They typically cause significant infection only when the oral mucosa is significantly disrupted and host defense mechanisms are compromised, for example, in neutropenic patients with cancer [ 34 ].
The first cases of viridans streptococcal bacteremia in neutropenic patients with cancer were described inwhen 29 episodes of bacteremia were observed in adults and children at the National Cancer Institute in Bethesda [ 5 ] and 6 episodes were reported in children at the M. Anderson Cancer Center in Houston [ 6 ]. Since then, the isolation of these microorganisms has become more frequent.
On the basis of these findings, it is critical for physicians to consider the diagnosis of serious infection caused by viridans streptococci in patients with cancer who have neutropenia and fever. We review the epidemiological factors that increase risk of infection and the clinical manifestations and management of this emerging infectious disease. The frequency at which viridans streptococci are isolated from the blood of neutropenic patients with cancer has significantly increased over the course of the last viridaans years [ 34 ].
Infection caused by viridans streptococci also has been a significant problem after bone marrow transplantation. In one study, viridans streptococci were recovered from the blood of 35 All of these studies indicate that these microorganisms have emerged as an important cause of bacteremia in immunocompromised patients. A number of risk factors are associated with an increased incidence of viridans streptococcal bacteremia in neutropenic patients with cancer table 2 [ 347—18 ].
Because the selection criteria for the control populations varied depending on the individual study and because not all studies were case controlled, published reports have identified a variety of risk factors in univariate analyses.
The factors identified as significant in various multivariate analyses are discussed in more detail below. Severe neutropenia has been identified as an important risk factor for viridans streptococcal bacteremia. Although the association between severe neutropenia and viridans streptococcal bacteremia has been confirmed in some studies, others have indicated that bacteremia can occur in patients with less-severe neutropenia [ 131419 ].
Mucositis, particularly in the oral cavity, appears to be another important factor predisposing patients to viridans streptococcal bacteremia [ 111517 ]. In an estreptpcoco of data from 25 neutropenic patients with viridans streptococcal bacteremia [ 15 ], viridans streptococci with the same ribotype as the strain responsible for the bacteremia were recovered from the mouths of all patients before the onset of bacteremia.
This demonstrates that the oral cavity is an important source of this microorganism and strongly suggests that disruption of the oral mucosa may lead to development of bacteremia. Localized oral infection with herpes simplex virus may also be important; this was found to be a risk factor in a study that showed that the incidence of viridans streptococcal bacteremia decreased in allogeneic bone marrow transplant recipients after administration of acyclovir [ 20 ].
However, oral infection with herpes simplex virus has not been identified as a risk factor in other studies. In addition to the oral cavity, the stomach may be an important point of entry for viridans streptococci.
The presence of ulcers induced by chemotherapeutic regimens may allow streptococci virivans grow in an environment that has been made relatively more alkaline by esterptococo administration of antacids or histamine type 2 receptor antagonists. However, this finding has not been viridxns by other studies [ 3 ]. Administration of high-dose cytosine arabinoside has been implicated as another important risk factor for viridans streptococcal bacteremia [ 81216 ].
In addition, repeated administration of high-dose chemotherapy may increase the risk, as esteeptococo demonstrated in an analysis in which the risk of developing viridans streptococcal bacteremia was found to be 21 times higher for patients who were repeatedly exposed to high-dose chemotherapy than it was for patients receiving a first course of chemotherapy [ 15 ].
What are Streptococcal infections?
Antimicrobial prophylaxis may also play an important role in the increase in the incidence of viridans streptococcal bacteremia. This is not surprising, because viridans streptococci typically are resistant to these antimicrobial agents, and use of these agents would select for viridans streptococcal colonization.
A consensus is lacking for several other potential risk factors table 2. In some studies, children appear to be at higher risk than adults for viridans streptococcal sepsis [ 10192122 ]. Similarly, bone marrow transplantation may also be a risk factor. However, case patients were more likely to have received intravenous hyperalimentation and prophylaxis with trimethoprim-sulfamethoxazole or a fluoroquinolone and were more likely to have stayed in a laminar flow room than were control subjects.
In the multivariate analysis, hyperalimentation, a stay in a laminar flow room, and bone marrow transplantation were not significant risk factors for viridans streptococcal bacteremia.
In one case study, fever appeared an average of 9. Fever may persist for days, even though blood culture results rapidly become negative. Other findings include flushing, chills, stomatitis, and pharyngitis. The species usually implicated in this syndrome include S.
This syndrome is seldom encountered in patients without neutropenia. Viridans streptococcal shock syndrome may occur early or within 2—3 days after presentation and progresses to respiratory failure within 48 h [ 3471018 ]. Shock may appear despite rapid clearance of viable bacteria from the bloodstream [ 22 ].
In severe cases, ARDS may be observed, usually 2—3 days after the onset of bacteremia. It is unusual, however, to find localized sites of infection.
Rash and desquamation of the palms and soles have also been reported usually 8—14 days after the onset of infection [ 7 ]. The rash, when it occurs, is maculopapular, beginning at the trunk and spreading to the face and extremities centrifugally.
The causative species in patients with viridans streptococcal shock syndrome has been S. The pathogenesis of this syndrome is not entirely clear. Although it has been postulated that some viridans streptococcal strains might produce a toxin similar to pyrogenic toxin A, which is produced by group A streptococci [ 22 ], no exotoxin or other virulence factor of viridans streptococci has been directly implicated in this syndrome.
Pulmonary infiltrates are frequent in severe cases of viridans vlridans bacteremia [ 4 ].
In some cases, this may be related to ARDS, to the pulmonary toxicity of cytosine arabinoside, or to other factors. A postmortem study of 3 patients who died after viridans streptococcal shock syndrome demonstrated 2 morphological phases [ 10 ]: Initial reports of viridans streptococcal bacteremia in patients with cancer and neutropenia revealed that these microorganisms were uniformly susceptible in vitro to penicillin.
However, resistance of viridans streptococci to a number of antimicrobial agents has been increasingly recognized, and penicillin susceptibility can no longer be assumed. In patients with cancer, neutropenia, and viridans streptococcal bacteremia, similar patterns of resistance have been reported table 3 [ 182728 ].
In vitro resistance of viridans streptococci to vancomycin has not been reported. The fluoroquinolones, including the newer agents, are not sufficiently active against viridans streptococci to warrant use in treatment or prophylaxis.
Antimicrobial selection for viridanx of viridans streptococcal infections must take into account the estreptocooc in vitro pattern of antimicrobial susceptibility. Although this approach may successfully decrease the mortality associated with viridans streptococcal disease, the potential that infections caused by other resistant pathogens, such as vancomycin-resistant Enterococcus species, may be promoted must be carefully considered.
As always, each medical center should develop its own guidelines, but we believe that empirical therapy with vancomycin should be used only for those neutropenic patients with cancer who have shock or are developing ARDS.
However, bacteremia may not always be the only factor leading to the patient’s death. Because viridans streptococci are now an important emerging pathogen among patients with neutropenia, especially those who are undergoing bone marrow transplantation, some centers are using antimicrobial agents that have in vitro activity against these microorganisms to decrease colonization and, it is hoped, to prevent infection [ 34 ]; the agents used have included penicillin, ampicillin, vancomycin, and roxithromycin.
At one center, the incidence of streptococcal bacteremia was reduced from In another study, 22 8. Furthermore, those patients who received a fluoroquinolone and penicillin had an even higher rate of oropharyngeal colonization with viridans streptococci than did patients who virifans a fluoroquinolone alone. Virkdans results contrast with those of another study, in which prophylactic use of ampicillin failed to decrease the incidence of viridans streptococcal sepsis among bone marrow transplant recipients [ 9 ].
Although the published data generally suggest that prophylactic administration of antimicrobial agents that have in vitro activity against the viridans streptococci reduces the incidence of significant infection, further development of resistance in viridans streptococci and other microorganisms is of great concern [ 1828 ].
In addition, case-fatality rates may be higher among neutropenic patients with penicillin-resistant viridans streptococcal bacteremia than among those with infection caused by penicillin-susceptible strains [ 2734 ]. Given the serious nature of septicemia caused by viridans streptococci and the potential for selection of resistant microorganisms including viridans streptococci, enterococci, and gram-negative bacilli that may cause significant disease and increased morbidity and mortality in neutropenic patients with cancer, we believe that the routine practice of using antimicrobial prophylaxis for this patient group should be reconsidered.
In vitro susceptibility of viridans streptococci isolated from neutropenic patients with cancer to selected antimicrobial agents.
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Sign In or Create an Account. Close mobile search navigation Article navigation. Abstract The frequency of isolation of viridans streptococci from the blood of neutropenic patients with cancer has significantly increased over the course of the last 10—15 years. Changing epidemiology of infections in patients with neutropenia and cancer: Bacteremia due to viridans streptococci in neutropenic patients: Septicemia and shock syndrome due to viridans streptococci: Bacteremia due to viridans streptococcus in neutropenic patients with cancer: Streptococcus viridans bacteremia following autologous peripheral blood stem cell transplantation.
Septicaemia caused by viridans streptococci in neutropenic patients with virdans. Streptococcal bacteremia estreptocovo adult patients with leukemia undergoing aggressive chemotherapy: Streptococcus mitis sepsis in bone marrow transplant patients receiving oral antimicrobial prophylaxis. Viridans streptococcal bacteraemia in patients with haematological and solid malignancies. Cytosine arabinoside as a major risk factor for Streptococcus viridans septicemia following bone marrow transplantation: Serious complications of bacteremia caused by viridans streptococci in neutropenic patients with cancer.
The clinical spectrum of infections with viridans streptococci in bone marrow transplant patients.