Streptococcus species

Michael Melia, M.D.

MICROBIOLOGY

  • Nomenclature and taxonomy of streptococci confusing because of many historical efforts at describing the class.
  • Often described by 5% sheep blood agar hemolysis (1902) or Lancefield carbohydrate group antigens (1933).
  • Broadly organized into two groups by hemolysis, Lancefield and phenotype testing (1937):
    1. Pyogenic (beta-hemolytic) including Groups A, B, C, E, F & G.
      • Group A streptococci: cause complete hemolysis/lysis of red cells in blood agar media around/under colonies caused by streptolysin (exotoxin), so called β-hemolysis. See separate module for details on this organism.
    2. Viridans group
      • Usually yield α-hemolysis on blood agar (green surrounding colony - hence name, viridans); may be β-hemolytic or non-hemolytic (latter sometimes termed γ-hemolysis).
  • Other organisms previously classified as Streptococci are now separate genera:
    • Lactococci: generally not human pathogens.
    • Enterococci: see separate module.
    • Streptococcal-like, catalase-negative, Gram-positive cocci.
      • e.g., Leuconostoc, Pediococcus
    • Formerly nutritionally-variant Streptococci
      • Abiotrophia, Granulicatella
  • 16S rRNA gene sequencing (1990’s) yield true phylogenetic relationships. Facklam classification presented here (see references).

CLINICAL

  • Group A streptococci: S. pyogenes (see separate pathogen module).
  • Group B streptococci (S. agalactiae):
    • Cause of neonatal sepsis/meningitis, puerperal sepsis, chorioamnionitis, peripartum endometritis, bacteremia (often without clear source), skin and soft-tissue infections, septic arthritis, pneumonia, endocarditis, osteomyelitis.
    • Found in GI/GU tracts. More common in adults >65 and those w/ co-morbidities.
  • Groups C, F, G streptococci: bacteremia, endocarditis, septic arthritis, osteomyelitis, pharyngitis, skin and soft tissue infections, meningitis, puerperal infection, neonatal sepsis.
  • Group D streptococci (non-enterococcal, e.g., S. gallolyticus subsp. gallolyticus (formerly S. bovis biotype I): associated with colonic malignancy and hepatobiliary disease. Cause of endocarditis.
  • S. intermedius/S. anginosus/S. constellatus group (microaerophilic strep; "S. milleri" no longer appropriate): propensity for invasion, meningitis, abscess production (e.g., head & neck infections), bacteremia.
    • Rarely "contaminants" when present in blood cultures.
  • S. suis: zoonotic pathogen associated with pig farming or exposure to contaminated pork products.
    • Most prevalent in southeast Asia, where it is a common cause of meningitis, hearing loss, cutaneous lesions, and bacteremia.
  • Viridans Streptococci: oropharynx/GI tract usual niche. Usually α-hemolytic or non-(γ)-hemolytic.
    • Common cause of dental infections, subacute bacterial endocarditis, bacteremia.
    • If isolated from CSF or respiratory sections, usually contaminants, but occasionally responsible for disease.
    • May also be common bloodstream contaminant, but need to clinically correlate and rule out systemic process such as endocarditis.
    • Heterogeneous group: may be commensals or pathogens. Little consistency in describing, usually six major groups in modern era.
      • S. mutans
      • S. salivarius 
      • S. anginosus 
      • S. mitis 
      • S. sanguinis 
      • S. bovis 
  • Abiotrophia and Granulicatella spp (formerly known as nutritionally-variant streptococci): endocarditis
  • Streptococcus pneumoniae (see separate pathogen module).

SITES OF INFECTION

  • Blood: primary bacteremia, especially with neutropenia or malignancy
  • Cardiovascular: endocarditis
  • Head and neck: dental infections, deep neck space infections (including submandibular, retropharyngeal and lateral neck)
  • Lung: pneumonia (rare) associated with oropharyngeal aspiration, abscess and empyema
  • Abdomen: abscesses including liver, cholangitis, visceral infections, GU tract
  • Shock syndrome (low BP, rash, ARDS) due to viridans strep (e.g., S. mitis) most frequently described in cancer patients
  • CNS: brain abscess, meningitis
  • Musculoskeletal: septic arthritis, cellulitis, osteomyelitis
  • GI tract: S. gallolyticus subsp. gallolyticus colonizes >55% of patients with colorectal cancer (10% of normal population)

TREATMENT

General Considerations Regarding Streptococcal Endocarditis

  • See endocarditis module for additional details.
  • Four week duration of therapy considered standard. Short course (2 wk) possible if certain criteria met.
  • Criteria favoring 2-wk short course beta-lactam + aminoglycoside combination for endocarditis:
    1. PCN sensitive oral viridans Streptococci or S. bovis (PCN MIC < 0.125mg/L).
    2. Native valve endocarditis.
    3. No heart failure, aortic insufficiency or conduction abnormality.
    4. No metastatic infectious foci.
    5. Quick clinical response and afebrile within 7d.

Viridans Streptococci

  • Cause of primary bacteremia, but up to 80% of cultures may represent contaminants or transient bacteremia.
    • Don’t dismiss in cancer pts on chemotherapy or if neutropenic.
    • Continuous bacteremia → suspect endocarditis.
  • Viridans group responsible for declining percentage of endocarditis compared to "enteric" strep such as S. gallolyticus subsp. gallolyticus and Enterococci, probably due to aging population and less rheumatic heart disease.
    • For endocarditis use pathogen module of bloodstream isolate for therapy specifics.
  • Therapy: β-lactams are preferred therapy.
    • Penicillin G 2-3 million U IV q4h +/- gentamicin for synergy 1.0 mg/kg/q8h IV
    • Ceftriaxone 2 g IV once daily
    • Vancomycin 15 mg/kg IV q12h (if PCN allergic)
    • Others:
      • Tetracyclines, macrolides, clindamycin: use with caution as 25-50% isolates resistant.
      • Note: TMP/SMX >75% resistance rates.
      • Do not be reassured by reported daptomycin susceptibility: Development of high-level daptomycin resistance with daptomycin exposure has been described.
    • There is increasing resistance to beta-lactams, esp. S. mitis (>40%).
  • Duration 10-14 days (not endocarditis).

Streptococcus anginosus group

  • Group comprises 3-15% of streptococcal isolates of endocarditis.
    • See Endocarditis module for management of this infection, follow viridans Streptococci recommendations.
  • Non-endocarditis infections: more frequently seen than endocarditis

Group B Streptococcus (S. agalactiae)

  • Treatment:
    • Bacteremia, soft tissue infections: PCN G 10-12 million units/d x 10d (e.g., 2MU q4h or six divided doses/d).
    • Meningitis (adult): PCN G 20-24 million units/d x 14-21d.
    • Osteomyelitis: PCN G 20-24 million units/d x 4-6w.
    • Endocarditis: PCN G 20-24 million units/d x 4-6w AND gentamicin 1mg/kg q8h for first 2 wks.
    • PCN allergic: may substitute vancomycin 15 mg/kg IV q 12h for PCN, although vancomycin resistance has been reported.
      • Clindamycin can be considered, but rates of resistance vary. Confirm absence of inducible clindamycin resistance (typically associated with macrolide resistance) before using as monotherapy.
    • Because GBS is slightly more resistant to penicillin than GAS, some add gentamicin (1 mg/kg q8h IV) for any serious GBS infection.
    • Skin and soft tissue infections:
      • Cellulitis (mild): penicillin VK 250-500 mg po q6h or, if concurrent MSSA infection not excluded, cephalexin 500 mg po q6h x5d
      • Cellulitis (moderate or severe): PCN 2-4 million units IV q4-6h or (if PCN allergic) clindamycin 600-900 mg IV q8h or, if concurrent MSSA infection not excluded, nafcillin 1-2 g IV q4-6h or cefazolin 1 g IV q8h
        • Cellulitis can typically be treated with 5d antibiotic therapy provided clinical improvement has occurred
        • Concurrent supportive care measures and treatment of toe web abnormalities (for lower extremity cellulitis) important
      • Impetigo (non-bullous, mild): Topical mupirocin or retapamulin BID x5d
      • Impetigo (non-bullous; many lesions or many persons affected): Cephalexin 250 mg po q6h x7d or dicloxacillin 250 mg po q6h x7d or (if PCN allergic) clindamycin 300-450 mg po q6h x7d
  • Prevention of perinatal infection:
    • Indications for peripartum antibiotic prophylaxis to prevent early-onset (within seven days of birth) disease:
      • Recovery of GBS from the urine during pregnancy
      • Prior delivery of an infant who sustained invasive GBS disease
      • Positive vaginal and/or rectal swabs at 35-37 weeks gestation (universal screening recommended if above criteria not met)
      • If no screen result available, prophylax if:
        • < 37 weeks gestation
        • Membrane rupture ≥18h
        • Intrapartum temperature >38C°
        • Intrapartum NAAT positive for GBS
      • No need for prophylaxis if cesarean delivery prior to rupture of amniotic membranes
    • Recommended prophylactic regimens:
      • Penicillin 5 million units IV x1, then 2.5-3.0 million units IV q4h until delivery
      • Ampicillin 2 grams IV x1, then 1 gram IV q4h
      • PCN allergic (non-anaphylactic, non-urticarial): cefazolin 2 grams IV x1, then 1 gram IV q8h
      • PCN allergic (anaphylactic or urticarial): clindamycin 900 mg IV q8h or vancomycin 1 g IV q12h (for clindamycin-resistant strains).
        • D-test should be performed to confirm absence of inducible clindamycin resistance.
      • Erythromycin not recommended.

Group D Streptococci

  • Penicillin high-level resistance not described, some strains resistant to clindamycin.
  • Bacteremia: PCN 12-18 million units/d IV x 10-14d.
  • Endocarditis:
    • If highly-susceptible to PCN: PCN 12-18 million units/d IV x 4 weeks
      • Consider adding gentamicin 1mg/kg q8h to shorten duration to 2wks
    • If PCN MIC >0.12 to < 0.5: PCN 24 MU/d x4w + gentamicin 1 mg/kg q8h x2w
    • If PCN MIC >0.5 (rare): PCN 24 MU/d + gentamicin 1 mg/kg q8h x4-6w
  • For bacteremia or endocarditis: Evaluate GI tract to exclude malignancy.

Group C, E, F Streptococci:

  • Bacteremia, septic arthritis or other serious infection: PCN 12-18 million units/d IV ± synergistic gentamicin (1 mg/kg IV q8h) x 10-14d.
    • Emergence of high-level aminoglycoside resistance has been described among GGS.
  • Cellulitis (mild): penicillin VK 250-500 mg po q6h or, if concurrent MSSA infection not excluded, cephalexin 500 mg po q6h x5d
  • Cellulitis (moderate or severe): PCN 2-4 million units IV q4-6h or clindamycin 600-900 mg IV q8h or, if concurrent MSSA infection not excluded, nafcillin 1-2 g IV q4-6h or cefazolin 1 g IV q8h
    • Cellulitis can typically be treated with 5 days of antibiotic therapy provided clinical improvement has occurred
    • Concurrent supportive care measures and treatment of toe web abnormalities (for lower extremity cellulitis) important
  • Endocarditis: see Endocarditis module using viridans streptococci recommendations for specifics.
  • Impetigo (non-bullous, mild): Topical mupirocin or retapamulin twice daily x5d
  • Impetigo (non-bullous; many lesions or many persons affected): Cephalexin 250 mg po q6h x7d or dicloxacillin 250 mg po q6h x7d or (if PCN allergic) clindamycin 300-450 mg po q6h x7d.
  • Group C and G Streptococci:
    • Oxacillin and nafcillin are ineffective.
    • Resistance to tetracycline, erythromycin, fluoroquinolones described.

Abiotrophia and Granulicatella spp:

  • Mainly a cause of endocarditis.
  • Less susceptible in vitro to PCN than other streptococci.
    • 33-67% of strains are relatively PCN-resistant (MIC 0.25-2.0 µg/mL).
    • Some isolates are highly resistant (MIC ≥4 µg/mL).
  • High-level aminoglycoside resistance has not been reported.
  • See Endocarditis module using viridans Streptococci recommendations, though would not use 2wk "short-course" therapy.

Streptococcus suis

  • Meningitis: Ceftriaxone 2 grams IV q12h x14 days; also consider penicillin G 24 million units/d x10-14 days.
  • Patients who relapse after two weeks of therapy should received prolonged treatment (4-6 wks).
  • Dexamethasone 0.4mg/kg q12h x 4d is standard recommendation for confirmed bacterial meningitis among adults in Southern Vietnam as morbidity and mortality has been shown to be reduced with administration.

Streptococcus pyogenes (Group A Strep)

Streptococcus pneumoniae (Pneumococcus)

Selected Drug Comments

Drug

Recommendation

Ceftriaxone

Once a day IV/IM cephalosporin with activity against almost all strains of streptococci.

Cephalexin

Active against most streptococci, though lower bioavailability and frequent dosing make it a choice for less serious infections.

Clarithromycin

Resistance not uncommon for many species.

Clindamycin

Available in both PO and IV forms. Well tolerated, but high incidence of C. difficile associated colitis. Not reliably active against viridans Streptococci and GBS.

Erythromycin

Resistance not uncommon for many species.

Gentamicin

May add for synergy in setting of endocarditis, serious bacteremia or if PCN MIC > 0.1.

Penicillin

Preferred therapy for susceptible strains of streptococci.

Vancomycin

Active against nearly all strains of streptococci. Must be given IV. Usually only used in settings of PCN allergy.

Daptomycin

Emergence of resistance on therapy has been described for viridans Streptococci.

OTHER INFORMATION

  • Viridans streptococci:
    • A high proportion of blood cultures growing viridans streptococci may be due to cutaneous contamination or transient oral bacteremia.
    • Penicillin-resistance w/ viridans streptococci not due to beta-lactamase production (hence no benefit from using agents such as ampicillin/sulbactam).
  • S. anginosus group especially confusing as can be either beta-hemolytic or non-hemolytic.
  • Recurrent invasive Group B Streptococcal infection described in 4% of nonpregnant adults within one year of first episode.
  • Consider Abiotrophia or Granulicatella (formerly nutritionally-variant strains) in "culture negative" endocarditis.
    • Special media historically required, though many modern broth micro systems should recover these organisms.
  • While U.S. incidence rates of meningitis caused by pneumococcus, meningococcus, L. monocytogenes, and H. influenzae decreased significantly from 1998-2007, incidence rates for S. agalactiae meningitis (as well as bacterial meningitis incidence rates among infants < 2 months) did not decrease.
  • Collecting vaginal swabs for real time GBS PCR and culture at the beginning of labor has been studied and may reduce unnecessary antibiotic therapy among previously culture-positive pregnant women; additional studies needed.

Basis for recommendation

  1. Baddour LM, Wilson WR, Bayer AS, et al. Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications: A Scientific Statement for Healthcare Professionals From the American Heart Association. Circulation. 2015;132(15):1435-86.  [PMID:26373316]

    Comment: Endocarditis treatment recommendations are based upon this document.

  2. Stevens DL, Bisno AL, Chambers HF, et al. Executive summary: practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of america. Clin Infect Dis. 2014;59(2):147-59.  [PMID:24973422]

    Comment: Far-reaching, comprenhensive review of skin and soft tissue infections, including those caused by beta-hemolytic Streptococci (with treatment recommendations as noted herein) as well as more common pathogens such as S. pyogenes and S. aureus

References

  1. Berbari EF, Kanj SS, Kowalski TJ, et al. 2015 Infectious Diseases Society of America (IDSA) Clinical Practice Guidelines for the Diagnosis and Treatment of Native Vertebral Osteomyelitis in Adults. Clin Infect Dis. 2015;61(6):e26-46.  [PMID:26229122]

    Comment: Osteomyelitis treatment recommendations are based upon this document.

  2. Park C, Nichols M, Schrag SJ. Two cases of invasive vancomycin-resistant group B streptococcus infection. N Engl J Med. 2014;370(9):885-6.  [PMID:24571775]

    Comment: Letter describing two seemingly unrelated clinical cases of vancomycin resistance to GBS. Both isolates were identified as vancomycin-nonsusceptible by local and state health authorities.

  3. García-de-la-Mària C, Pericas JM, Del Río A, et al. Early in vitro and in vivo development of high-level daptomycin resistance is common in mitis group Streptococci after exposure to daptomycin. Antimicrob Agents Chemother. 2013;57(5):2319-25.  [PMID:23478959]

    Comment: This work describes experimental models demonstrating the emergence of high-level daptomycin resistance upon exposure to daptomycin among viridans Streptococci isolates initially found to be susceptible to daptomycin. The addition of low-dose gentamicin prevented the emergence of daptomycin resistance in 91% of rabbits in their model.

  4. Fairlie T, Zell ER, Schrag S. Effectiveness of intrapartum antibiotic prophylaxis for prevention of early-onset group B streptococcal disease. Obstet Gynecol. 2013;121(3):570-7.  [PMID:23635620]

    Comment: Use of at least four hours of antimicrobial prophylaxis with either penicillin or ampicillin was 86-91% effective in preventing early-onset neonatal GBS disease. Use of clindamycin was significantly less effective, highlighting the need to use cefazolin, not clindamycin, for pregnant women without a history of anaphylaxis or urticaria upon exposure to penicillins.

  5. Poncelet-Jasserand E, Forges F, Varlet MN, et al. Reduction of the use of antimicrobial drugs following the rapid detection of Streptococcus agalactiae in the vagina at delivery by real-time PCR assay. BJOG. 2013;120(9):1098-108.  [PMID:23656626]

    Comment: Molecular testing to detect genital tract GBS colonization has been extensively studied, with excellent sensitivity and specificity. This analysis found such testing to be associated with lower rates of antibiotic administration when compared with convential culture-based diagnostics at 34-38 weeks gestation. Use of molecular diagnostics may lower rates of needless antibiotic administration (and its associated sequelae) at the cost of the greater expense of real-time PCR testing.

  6. Thigpen MC, Whitney CG, Messonnier NE, et al. Bacterial meningitis in the United States, 1998-2007. N Engl J Med. 2011;364(21):2016-25.  [PMID:21612470]

    Comment:
    Nice epidemiologic summary of incidence rates of meningitis due to Pneumococcus, Meningococcus, L. monocytogenes, H. influenza, and S. agalactiae based upon laboratory- and population-based surveillance data. Rates of meningitis due to all pathogens save S. agalactiae decreased significantly over the interval.

  7. Boleij A, Muytjens CM, Bukhari SI, et al. Novel clues on the specific association of Streptococcus gallolyticus subsp gallolyticus with colorectal cancer. J Infect Dis. 2011;203(8):1101-9.  [PMID:21451000]

    Comment:
    Interesting discussion of the pathogenic mechanisms by which (a) GI tract colonization with S. gallolyticus subsp. gallolyticus might increase among persons with colorectal cancer, and (b) increased incidence rates of endocarditis caused by this pathogen among these patients might be explained.

  8. Verani JR, McGee L, Schrag SJ, et al. Prevention of perinatal group B streptococcal disease--revised guidelines from CDC, 2010. MMWR Recomm Rep. 2010;59(RR-10):1-36.  [PMID:21088663]

    Comment:
    Excellent CDC guideline statement regarding the role of screening expectant mothers and administering prophylactic antibiotic therapy to reduce rates of invasive GBS disease among newborns. The universal screening strategy initially recommended in 1996 and revised twice since then has been associated with substantial rates in reduction of early-onset invasive GBS disease.

  9. Doern CD, Burnham CA. It's not easy being green: the viridans group streptococci, with a focus on pediatric clinical manifestations. J Clin Microbiol. 2010;48(11):3829-35.  [PMID:20810781]

    Comment: A relatively easy to understand review of green strep, though this remains fluid with to be sure future changes.

  10. Wertheim HF, Nghia HD, Taylor W, et al. Streptococcus suis: an emerging human pathogen. Clin Infect Dis. 2009;48(5):617-25.  [PMID:19191650]

    Comment: Interesting review article highlighting the emergence of S. suis as a zoonotic pathogen among pig farmers, particularly in southeast Asia, where it is a not uncommon cause of meningitis and hearing loss.

  11. Sendi P, Johansson L, Norrby-Teglund A. Invasive group B Streptococcal disease in non-pregnant adults : a review with emphasis on skin and soft-tissue infections. Infection. 2008;36(2):100-11.  [PMID:18193384]

    Comment: Comprehensive review of invasive S. agalactiae infections in non-pregnant adults. Authors note that diabetes and immunocompromise increase risk of infection. Bacteremia and skin/soft tissue infections are the most common kinds of infections, although toxic shock syndrome and necrotizing fasciitis are more recently recognized conditions related to this bacterium.

  12. Nguyen TH, Tran TH, Thwaites G, et al. Dexamethasone in Vietnamese adolescents and adults with bacterial meningitis. N Engl J Med. 2007;357(24):2431-40.  [PMID:18077808]

    Comment: Although controversial, dexamethasone is now used as part of the treatment of adults with confirmed or suspected bacterial meningitis in southern Vietnam, in large part because of the positive impact on morbidity and mortality seen in cases of S. suis meningitis in this study.

  13. Schoening TE, Wagner J, Arvand M. Prevalence of erythromycin and clindamycin resistance among Streptococcus agalactiae isolates in Germany. Clin Microbiol Infect. 2005;11(7):579-82.  [PMID:15966978]

    Comment: Levels of resistance seen with overall frequencies of erythromycin and clindamycin resistance were 11% and 4.7%, respectively. Inducible resistance was documented in some.

  14. Crum NF, Russell KL, Kaplan EL, et al. Pneumonia outbreak associated with group a Streptococcus species at a military training facility. Clin Infect Dis. 2005;40(4):511-8.  [PMID:15712072]

    Comment: Largest outbreak of severe Group A strep pneumonia in > 30 years occurred in a military setting. This speaks to the potential for this organism to cause epidemic disease in close settings.
    Rating: Important

  15. Edwards MS, Rench MA, Palazzi DL, et al. Group B streptococcal colonization and serotype-specific immunity in healthy elderly persons. Clin Infect Dis. 2005;40(3):352-7.  [PMID:15668856]

    Comment: Raising rates of GBS infection in the elderly may be explained by the finding that colonization rates are similar, but elderly are more likely to be colonized by the V type that causes invasive disease.
    Rating: Important

  16. Zheng X, Freeman AF, Villafranca J, et al. Antimicrobial susceptibilities of invasive pediatric Abiotrophia and Granulicatella isolates. J Clin Microbiol. 2004;42(9):4323-6.  [PMID:15365035]

    Comment: Among 15 Abiotrophia and Granulicatella isolates, ten demonstrated intermediate resistance to penicillin, and 3 were resistant.

  17. Gold JS, Bayar S, Salem RR. Association of Streptococcus bovis bacteremia with colonic neoplasia and extracolonic malignancy. Arch Surg. 2004;139(7):760-5.  [PMID:15249410]

    Comment: Retrospective study highlights long known association with colon cancer (17/45 pts 41%), but also notes that 5/45 were found to have an extra-gastrointestinal malignancy.

  18. Claridge JE, Attorri S, Musher DM, et al. Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus ("Streptococcus milleri group") are of different clinical importance and are not equally associated with abscess. Clin Infect Dis. 2001;32(10):1511-5.  [PMID:11317256]

    Comment: The authors report data on 122 cases of Streptococcus milleri (now called either Streptococcus intermedius or S. anginosus Group) infection over a 1 year period. They found that 41/56 isolates of S. constellatus, 10/14 S. intermedius and 10/52 S. S. constellatus infections were associated with abscess formation. In addition, they note that S. intermedius was usually found as a monomicrobial pathogen, while S. constellatus and S. anginosus tended to cause polymicrobial infections.

  19. Pfaller MA, Jones RN, Doern GV, et al. Survey of blood stream infections attributable to gram-positive cocci: frequency of occurrence and antimicrobial susceptibility of isolates collected in 1997 in the United States, Canada, and Latin America from the SENTRY Antimicrobial Surveillance Program. SENTRY Participants Group. Diagn Microbiol Infect Dis. 1999;33(4):283-97.  [PMID:10212756]

    Comment: Penicillin resistance among viridans group streptococci shown to have reached 48.5% in U.S among isolates tested.
    Rating: Important

  20. Schattner A, Vosti KL. Bacterial arthritis due to beta-hemolytic streptococci of serogroups A, B, C, F, and G. Analysis of 23 cases and a review of the literature. Medicine (Baltimore). 1998;77(2):122-39.  [PMID:9556703]

    Comment: Group A, B and G account for most cases, with only Group A associated with toxic-shock like features.
    Rating: Important

  21. Colford JM, Mohle-Boetani J, Vosti KL. Group B streptococcal bacteremia in adults. Five years' experience and a review of the literature. Medicine (Baltimore). 1995;74(4):176-90.  [PMID:7623653]

    Comment: This report is similar to five earlier studies showing that GBS in adult patients, most (66%) were more than 50 years old. Primary bacteremia was the most frequent clinical diagnosis, occurring in 7 (22%) of 32 patients. Nonhematologic cancer was the most frequently associated condition (25%). Nineteen percent of the patients had diabetes mellitis. The overall mortality rate was 31% and was significantly associated with increasing age.

  22. Shinzato T, Saito A. The Streptococcus milleri group as a cause of pulmonary infections. Clin Infect Dis. 1995;21 Suppl 3:S238-43.  [PMID:8749672]

    Comment: A study utilizing percutaneous microbiologic specimens of pulmonary infiltrates and pleural collections. A high proportion were found to involve organisms of the Streptococcus milleri group and synergy provided by oral anaerobic bacteria was demonstrated too.

  23. Elting LS, Bodey GP, Keefe BH. Septicemia and shock syndrome due to viridans streptococci: a case-control study of predisposing factors. Clin Infect Dis. 1992;14(6):1201-7.  [PMID:1623076]

    Comment: Report highlights the growing emergence of severe bacteremia (often continuous) in patients undergoing chemotherapy. Between 1972 and 1989, the incidence of viridans streptococcal bacteremia at the University of Texas M. D. Anderson Cancer Center in Houston increased from one case per 10,000 admissions to 47 cases per 10,000 admissions (P less than .0001). Risk factors also included TMP-SMX or FQ use, use of antacids leading others to suspect gastric source from chemotherapy-induced irritation. A shock syndrome w/hypotension, rash, palmar desquamation, ARDS developed in 26% of patients.
    Rating: Important

  24. Swenson FJ, Rubin SJ. Clinical significance of viridans streptococci isolated from blood cultures. J Clin Microbiol. 1982;15(4):725-7.  [PMID:7068840]

    Comment: Frequently cited paper indicating a high rate of rejection of blood cultures growing viridans streptococci as being contaminants (approximately 4 of 5 were felt to be such). This paper again highlights the "art" of medicine in the need to carefully weigh each situation rather than to have "knee jerk" responses to clinical microbiological data.
    Rating: Important

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Last updated: August 3, 2016