Controversies in new antibiotic therapy for ambulatory patients

 The care of the febrile neutropenic patient has undergone a shift in the last 10 years with the realization that neutropenic patients presenting with fever do not constitute a homogeneous group. Strategies of risk assessment have allowed the testing of novel therapies including oupatient treatment with oral and intravenous antibiotics, either in combination regimens or as monotherapy; the addition of growth factors to hasten the return of the absolute neutrophil count; and the possibility of self-initiation of antibiotics by cancer patients when they develop fever. The clinical trials data regarding these new approaches will be reviewed, and areas requiring further research will be discussed.     

Spinal metastases mimicking low back pain of mechanical origin: a case report

Spinal malignancies are an essential consideration when a patient presents to a chiropractic office with back pain. This single case report exemplifies the importance of patient presentation and physical examination findings. We must also consider the rationale for x-raying patients on an individual case basis. Textbook cases do not always exist and special diagnostic tests do not always provide a definitive diagnosis of underlying pathology. Even though history and examination findings suggest a routine diagnosis, continual re-evaluation and recognition of the need to change the diagnosis on occasion is extremely important. The patient should not only be thoroughly evaluated upon initial presentation, but also each time they present for treatment. The decision to x-ray a patient is considered important. X-ray examination can be used to confirm a diagnosis or to rule out potential pathologies, and not necessarily done as a routine screening procedure.A case report is presented in which the pathologic signs were not evident on plain film x-rays upon initial presentation.     

Septicemia and shock syndrome due to viridans streptococci: a case-control study of predisposing factors.

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). A shock syndrome characterized by hypotension, rash, palmar desquamation, adult respiratory distress syndrome, and occasionally death developed in 26% of cases of streptococcal septicemia but in only 4% of cases of septicemia involving other gram-positive bacteria (P = .0005). The risk of streptococcal infection increased with the prophylactic administration of trimethoprim-sulfamethoxazole or a fluoroquinolone (P less than .0001) and with profound neutropenia (P less than .0001). Treatment of chemotherapy-induced gastritis with antacids or with histamine type 2 (H2) antagonists was associated with a sevenfold increase in risk (P less than .001), while sucralfate therapy did not increase risk (P = .65). Streptococcal infection may result from gastric overgrowth of organisms resistant to trimethoprim-sulfamethoxazole in an antacid- or H2 antagonist-induced alkaline environment, with the gastrointestinal tract ulceration caused by antineoplastic therapy providing a convenient portal of entry. In patients receiving chemotherapy, replacement of antacids or H2 antagonists by an acid-sparing regimen should be considered to preserve the natural acidic barrier to infection.     

Stratification in clinical trials of febrile neutropenia

Patients with febrile neutropenia are characterized by well described prognostic factors leading to heterogeneity of risk of serious clinical outcomes. These prognostic factors complicate the design and interpretation of clinical trials of antimicrobial therapy in this population. Stratification is a method by which comparability of groups is ensured. This method can be employed prior to randomization or during the analysis. Factors that should be considered for stratification prior to randomization include the underlying neoplasm (leukemia vs solid tumor vs BMT), use of granulocyte growth factors, comorbid conditions and study site (in multicenter trials). In stratified analyses, trend in neutrophil count, site of infection, organism and susceptibility should be considered.     

On the interaction of rabbit antithrombin III with the luminal surface of the normal and deendothelialized rabbit thoracic aorta in vitro

Pure rabbit antithrombin III was isotope labeled (with 125I or 3H) by two different methods; neither procedure caused a loss of antithrombin activity although both methods affected the affinity of the protein for Sepharose-heparin. From segments from freshly excised rabbit aorta, the uptake of isotope-labeled antithrombin III by the endothelium was rapid and saturable, although relatively small compared to the uptake of thrombin; binding of 3H-antithrombin III to the endothelium resembled that of 125I-antithrombin III. Transendothelial passage of antithrombin III into the subendothelial layers (intima-media) was slow and progressive. Endothelium binding was not affected by pretreating the vessel with either heparin, thrombin, or glycosaminoglycan-specific enzymes. Endothelium-bound antithrombin III was not selectively displaced by either heparin or thrombin. In contrast, endothelium-bound thrombin was rapidly dislodged by antithrombin III as a thrombin- antithrombin III complex. The surface of the deendothelialized aorta (ie, subjected to a balloon catheter) bound antithrombin III avidly. Pretreatment of the deendothelialized vessel with glycosaminoglycan- specific enzymes, particularly heparitinase, decreased intima-media binding by up to 80%. 125I-antithrombin III, when bound to the deendothelialized vessel surface, was actively displaced by either heparin, thrombin, or by unlabeled antithrombin III. The relatively poor binding of antithrombin III compared with that of thrombin by the endothelium in vitro supports an earlier proposal (Lollar P, Owen WG: J Clin Invest 66:1222-1230, 1980) that thrombin bound to high-affinity sites, possibly pericellular proteoglycan, of the endothelium is inactivated by plasma antithrombin III in vivo. Such a situation probably holds for large arteries at least.     

Human platelet fibrinogen: purification and hemostatic properties

Conditions were developed in which 80% to 90% of platelet fibrinogen could be routinely purified in nondegraded form from the fluid phase of platelet suspensions stimulated with the calcium ionophore, A23187, in the presence of calcium, leupeptin, and prostaglandin E1. Fibrinogen was separated from other released proteins by chromatography on diethylaminoethanol (DEAE)-cellulose using a continuous pH and ionic strength gradient. Purified platelet fibrinogen, greater than 98% homogeneous by immunoelectrophoresis and sodium-dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE), consisted of intact A alpha, B beta and gamma A chains, but not gamma' chains, and was 95% to 96% clottable. Platelet fibrinogen was shown to compete for the binding of radiolabeled plasma fibrinogen to ADP-activated platelets in a manner identical to that of unlabeled plasma fibrinogen itself. Also, at equivalent protein concentrations, platelet and plasma fibrinogens supported platelet aggregation to an equivalent extent. Based upon these results, we conclude that there is no significant difference between platelet and plasma fibrinogen with respect to their size, their clottability, their affinity for the activated platelet fibrinogen receptor, or their capacity to support subsequent platelet aggregation.     

Serratia bacteremia: review of 118 cases

A review was conducted of 118 episodes of serratia bacteremia in cancer patients during a 16-year period. The infection occurred most commonly in patients with acute leukemia. Most patients acquired the infection in the hospital, and 61% had received antibiotic therapy during the preceding 10 days. Fever occurred in 90% of cases and shock in 18%. Thirty-eight percent of patients had concomitant pneumonia. Patients with shock, pneumonia, or hemorrhage had a substantially poorer prognosis. The response rate was 75% for patients who received appropriate antibiotics, 22% for those who received inappropriate antibiotics, and 29% for those who received no antibiotics. Patients who continued to have positive blood culture results while receiving appropriate antibiotic therapy had a poor diagnosis. Patients who received only an aminoglycoside had the poorest response rate among those who received appropriate therapy.