Serum bactericidal activity as a therapeutic guide in severely granulocytopenic patients with gram-negative septicemia

Polymyxin Combination Therapy and the Use of Serum Bactericidal Titers in the Management of KPC-Producing Klebsiella pneumoniae Infections: A Report of 3 Cases

Management of patients with KPC-harboring Enterobacteriaceae has become a significant and challenging scenario. We report three cases of KPC-producing Klebsiella pneumoniae bacteremia that were successfully treated using combination therapy with polymyxin B and other antimicrobials. Serum bactericidal titers were determined and provided additional clinical guidance in the management of such patients.

Comparison of two schedules of cefoperazone plus aztreonam in the treatment of neutropenic patients with fever

Cancer patients were randomized to receive an every 4 hour or every 8 hour schedule of cefoperazone plus aztreonam during 617 febrile episodes. The overall response rate for the 478 evaluable episodes was 76% and there was no difference in response rate between the two schedules. The response rate was 79% for cases of pneumonia and 63% for cases of bacteremia. Only 50% of the microbiologically documented infections caused by gram-positive organisms responded whereas 95% of gram-negative infections, including all of those caused by Pseudomonas aeruginosa, responded. Response rates were lower among patients whose neutrophil counts decreased during therapy than among those whose neutrophil counts increased (64% vs. 85%, p = 0.008). Side-effects that were possibly or probably related to antibiotic therapy were observed during 11% of the episodes. The most common side-effects were diarrhea and rashes including one case of Stevens-Johnson syndrome. Three patients developed a coagulopathy during therapy. Cefoperazone plus aztreonam proved to be an effective combination for treatment of gram-negative infections and fever of unknown origin in cancer patients and an every 8-hour schedule of administration was as effective as an every 4-hour schedule. Approximately half of the patients with gram-positive infections required additional antibiotics for successful therapy.

Empiric treatment of infection during granulocytopenia

Results from clinical trials conducted over the past 15 years suggest the following: a) Early empiric therapy with broad-spectrum antibiotics directed against Gram-negative bacillary bacteremia is necessary in febrile granulocytopenic cancer patients; b) The level and dynamics of the granulocyte count are extremely important in determining the outcome of bacteremia; c) Most empiric antimicrobial regimens will require therapeutic modifications; these alterations are necessary and contribute to a high overall success rate; d) Only microbiologically documented infections and especially bacteremias are useful for comparison of initial response to antimicrobial regimens; e) The response rate of Gram-negative bacillary bacteremia is clearly influenced by the susceptibility of the causative pathogen to the beta-lactam component of the empiric regimen; emergence of resistance to some beta-lactam antibiotics is quite common and necessitates successive modifications of empiric regimens with time; f) The combination of an anti-pseudomonal beta-lactam with an aminoglycoside is recommended as the standard for empiric therapy in febrile granulocytopenic cancer patients, especially in those with severe and persistent granulocytopenia who are suspected of having Gram-negative bacillary bacteremia; less neutropenic and/or asymptomatic patients may do well with monotherapy; g) Gram-positive pathogens have become a common cause of bacteremia in granulocytopenic cancer patients; the response rate to empiric regimens may be suboptimal but the associated mortality is low; h) Patients with severe granulocytopenia and protracted fever whose blood cultures remain negative are at high risk for contracting fungal infections; in these patients, empiric antifungal agents are probably indicated.

Cefoperazone in the treatment of infections in cancer patients

Cefoperazone appears to be one of the cephalosporins with the most promise in granulocytopenic patients, regardless of whether it is used in combination or as monotherapy. It has the broad spectrum of antimicrobial activity necessary to inhibit the organisms commonly encountered in patients with cancer, as well as the ability to achieve high serum levels for sustained periods of time. Administration of cefoperazone should provide effective therapy in the overall management of most infections encountered in patients with neoplastic diseases.

Cefotaxime plus amikacin as empiric therapy in the treatment of febrile episodes in neutropenic patients with hematologic malignancies

Between October 1980 and October 1981, cefotaxime plus amikacin were used in the treatment of 131 febrile episodes that occurred in 108 neutropenic patients with hematologic malignancies. The overall clinical response was 86.2%. Fevers of unknown origin and clinically or microbiologically documented infections responded in 88.8 and 84.4% of the cases, respectively. Renal toxicity occurred in 3.8% of the cases. In vitro studies showed that cefotaxime and amikacin were active against 78.7 and 94.7% of the pathogens, respectively, despite the high frequency (31%) of multiply resistant strains of Pseudomonas aeruginosa (defined as in vitro simultaneously resistant to carbenicillin, gentamicin, tobramycin and sisomicin) isolated from blood and infected sites. Synergy studies performed against 35 gram-negative bacilli isolated from blood revealed the presence of synergism between cefotaxime and amikacin in 54% of the cases. The peak levels of bactericidal activity in the serum of patients receiving cefotaxime plus amikacin showed median values of 1:128 and 1:8 against Escherichia coli and P. aeruginosa septicemias, respectively.

Superinfections during antimicrobial treatment with betalactam-aminoglycoside combinations in neutropenic patients with hematologic malignancies

The frequency, etiology and risk factors of superinfections during and/or within one week after antibiotic therapy with betalactam-aminoglycoside combinations were evaluated in 631 patients with hematologic malignancies admitted to the Institute of Hematology of Rome from January 1982 to December 1984. 356 patients (56%) developed 402 episodes of proven or presumed infection. Of these patients, 78 developed 102 superinfections. Overall, superinfections responded less satisfactorily to antibiotic therapy than the primary febrile episodes (63% vs. 85%). The distribution of etiologic agents of superinfections differed from those responsible for primary infections, since fungi and anaerobes (especially Clostridium difficile) were mostly isolated after antibiotic therapy had begun. Moreover, among aerobic bacteria, frequently antibiotic-resistant species, such as Pseudomonas aeruginosa, Streptococcus faecalis and Staphylococcus epidermidis were the leading etiologic agents of superinfection. The risk of superinfection appeared to increase with the depth and persistence of granulocytopenia. On the other hand, the length of hospitalization, length of previous antibiotic therapy, previous chemoprophylaxis and presence of indwelling venous catheter did not affect the risk of superinfection.