Viridans streptococci isolated by culture from blood of cancer patients: clinical and microbiologic analysis of 50 cases.

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 mug/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 > or =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.

Bacterial infections in low-risk, febrile neutropenic patients.

BACKGROUND: Accurate identification of low-risk, febrile neutropenic patients has become possible only recently. Many such patients are treated with oral antibiotics without hospitalization. To the authors' knowledge, data concerning the spectrum of bacterial infections in these patients are scarce, and collecting such data may have an impact on the choice of empiric oral regimen(s). METHODS: Using the same risk-prediction and eligibility criteria, four studies of empiric therapy in low-risk, febrile neutropenic patients were conducted at the authors' institution. Based on that experience, patients also were entered on clinical pathways for outpatient therapy. For the current study, microbiologic data were pooled from those trials and clinical pathways (757 episodes) to describe the nature and spectrum of infections seen in this setting. RESULTS: Unexplained fever occurred most often (58% of episodes), and both clinically documented and microbiologically documented infections were seen with equal frequency (21% of episodes, respectively). The most common clinical sites of infection were the upper respiratory tract, skin, and skin structure. Among microbiologically documented infections, monomicrobial, gram-positive infections accounted for 49% (with coagulase-negative staphylococci the most frequent); monomicrobial, gram-negative infections accounted for 36% (with Escherichia coli the most frequent); and 15% of infections were polymicrobial. CONCLUSIONS: In this description of the spectrum of infections in the largest cohort of low-risk febrile neutropenic patients to date, episodes of unexplained fever were predominant, but gram-positive, gram-negative, and polymicrobial infections also were documented. Although these patients were at low risk for complications, they required broad-spectrum antibiotic therapy when they developed neutropenic fever.

Acute thrombotic thrombocytopenic purpura following orthopedic surgery.

Release of unusually large von Willibrand factor (UL vWF) multimers and a deficiency of vWF metalloprotease may result in thrombotic thrombocytopenic purpura (TTP), a life threatening disease. Surgery has been associated with TTP, probably by releasing massive amounts of UL vWF. An association between TTP and orthopedic surgery has never been reported in the literature. We report a case of TTP following a total knee replacement surgery in which prior use of ticlopidine might have played a role.