Initial Empirical Antimicrobial Therapy: Duration and Subsequent Modifications

Evidence-based guidelines for empirical therapy of neutropenic fever in Korea

Neutrophils play an important role in immunological function. Neutropenic patients are vulnerable to infection, and except fever is present, inflammatory reactions are scarce in many cases. Additionally, because infections can worsen rapidly, early evaluation and treatments are especially important in febrile neutropenic patients. In cases in which febrile neutropenia is anticipated due to anticancer chemotherapy, antibiotic prophylaxis can be used, based on the risk of infection. Antifungal prophylaxis may also be considered if long-term neutropenia or mucosal damage is expected. When fever is observed in patients suspected to have neutropenia, an adequate physical examination and blood and sputum cultures should be performed. Initial antibiotics should be chosen by considering the risk of complications following the infection; if the risk is low, oral antibiotics can be used. For initial intravenous antibiotics, monotherapy with a broad-spectrum antibiotic or combination therapy with two antibiotics is recommended. At 3-5 days after beginning the initial antibiotic therapy, the condition of the patient is assessed again to determine whether the fever has subsided or symptoms have worsened. If the patient's condition has improved, intravenous antibiotics can be replaced with oral antibiotics; if the condition has deteriorated, a change of antibiotics or addition of antifungal agents should be considered. If the causative microorganism is identified, initial antimicrobial or antifungal agents should be changed accordingly. When the cause is not detected, the initial agents should continue to be used until the neutrophil count recovers.

Antibiotic Resistance of Non-Pneumococcal Streptococci and Its Clinical Impact

Viridans streptococci (VGS) form a phylogenetically heterogeneous group of species belonging to the genus Streptococcus (1). However, they have some common phenotypic properties. They are alfa- or non-haemolytic. They can be differentiated from S. pneumoniae by resistance to optochin and the lack of bile solubility (2). They can be differentiated from the Enterococcus species by their inability to grow in a medium containing 6.5% sodium chloride (2). Earlier, so-called nutritionally variant streptococci were included in the VGS but based on the molecular data they have now been removed to a new genus Abiotrophia (3) and are not included in the discussion below. VGS belong to the normal microbiota of the oral cavities and upper respiratory tracts of humans and animals. They can also be isolated from the female genital tract and all regions of the gastrointestinal tract (2, 3). Several species are included in VGS and are listed elsewhere (2, 3). Clinically the most important species belonging to the VGS are S. mitis, S. sanguis and S. oralis.

Efficacy of intravenous ciprofloxacin in patients with febrile neutropenia refractory to initial therapy

We previously reported that monotherapy with carbapenem or cefepime exhibited efficacy equivalent to cefepime plus an aminoglycoside as initial therapy for febrile neutropenia (FN), achieving an adequate response in two-thirds of the patients. However, only one-third of the remaining poor responders to monotherapy became afebrile after an aminoglycoside was added to the initial carbapenem or cefepime. The present study was designed to evaluate the benefit of intravenous ciprofloxacin for neutropenic patients with fever who were refractory to initial therapy given for the first 3 days. Patients with FN--as defined by an axillary temperature >or=37.5 degrees C and a neutrophil count <1,000/microL-who had no response to initial therapy with carbapenem or cefepime for 72 hours were to receive additional ciprofloxacin 600 mg/day. They were otherwise managed according to the Japanese guidelines for FN. An adequate response was defined as a decline of temperature to <37.5 degrees C within 7 days after initiation of ciprofloxacin treatment. Thirty-one patients with FN (seventeen male and fourteen female; mean age 53.1 +/- 14.8 years) were entered in the study. The initial antibiotics were cefepime (2 - 4 g/day) in twenty and carbapenem (1 - 2 g/day) in eleven. Three patients were excluded from analysis, leaving 28 patients for evaluation of efficacy. The response rate was 16/31 patients (51.6%),with four patients judged non-assessable due to adverse effects, protocol violation or early change to other agents. Adverse events occurred in seventeen patients, but all were mild and reversible. Only three patients had adverse events (skin rash, hepatic dysfunction and elevation of alkaline phosphatase in one patient, respectively) considered related to ciprofloxacin. These findings indicate that addition of intravenous ciprofloxacin is effective against FN refractory to initial antibiotic therapy and has acceptable toxicity.

[Management of febrile neutropenic patients]

High risk febrile neutropenia requires hospital treatment. The choice of antibiotic is determined by the resistance patterns of the pathogens predominating in each center. Monotherapy with an antipseudomonal beta-lactam can be the initial choice in most patients. However, initial beta-lactam-aminoglycoside combination therapy should be considered with infectious foci other than the catheter, in non-fermenting Gram-negative colonization, and when the patient has received beta-lactam treatment in the previous month. Combination therapy with glycopeptides should be considered if the focus of infection is the catheter, if there is colonization by methicillin-resistant Staphylococcus aureus or severe mucositis and both agents should be administered if there are criteria for severe sepsis. If there is no microbiologically documented infection, glycopeptides and/or aminoglycosides should be withdrawn promptly. Empirical antifungal therapy plays an important role in patients with persistent fever. In severe microbiologically documented infections, therapy should be maintained for a minimum of 14 days. Adjuvant therapy with granulopoiesis-stimulating factors is indicated in most patients.

Clinical guidelines for the management of neutropenic patients with unexplained fever in Japan: validation by the Japan Febrile Neutropenia Study Group

The Japan Febrile Neutropenia Study Group (JFNSG) Trial was a multicenter, open, randomized study designed to validate the first Japanese guidelines for the management of neutropenic cancer patients with unexplained fever issued in 1998. The trial compared cefepime monotherapy with cefepime plus amikacin combination therapy in febrile neutropenic patients with hematological disorders. The JFNSG found that monotherapy with cefepime was, in general, as effective as combination therapy. In terms of subset analyses, defervescence appeared to occur more frequently in leukemic patients and in those with profound neutropenia treated with the dual combination. The conclusion of the trial was that the 1998 guidelines were applicable to the Japanese febrile neutropenic patient population. The JFNSG met again in 2003 to revise these guidelines. An important addition to the guidelines was a distinction between low- and high-risk patients. Low-risk febrile neutropenic patients can receive oral ciprofloxacin or levofloxacin, with or without amoxicillin/clavulanic acid, on an outpatient basis, or intravenous (i.v.) monotherapy with cefepime, ceftazidime or a carbapenem. High-risk patients can receive i.v. cefepime, ceftazidime or a carbapenem, or an i.v. dual combination with cefepime, ceftazidime or a carbapenem plus an aminoglycoside. Those patients with a documented infection with methicillin-resistant Staphylococcus aureus should also receive a glycopeptide. It remains to be determined whether existing assessment scoring systems apply to Japanese patients; whether a broad-spectrum cephalosporin plus an aminoglycoside combination is required as the initial management of patients with acute leukemia and/or profound neutropenia; which antibacterial drugs should be used when first- and second-line agents fail; what are the appropriate oral agents and dosing regimens for low-risk patients; whether serology or the polymerase chain reaction should be the preferred marker for initiating preemptive antifungal therapy; and whether the azoles or the candins should be the preferred antifungal agents.

Monotherapy versus Dual Therapy Based on Risk Categorization of Febrile Neutropenic Patients

Cefepime monotherapy was compared with cefepime-plus-amikacin dual therapy for treatment of febrile neutropenic patients. Response rates were significantly lower for patients receiving monotherapy who had neutrophil counts of <500 cells/mm3 but did not differ significantly between patients receiving dual therapy who had neutrophil counts of > or =500 cells/mm3 or <500 cells/mm3. Dual therapy is recommended for the initial treatment of patients with neutropenia with <500 cells/mm3. Dual therapy was significantly more effective in patients with neutropenia lasting <5 days. The response rates to monotherapy or dual therapy did not differ significantly when neutropenia persisted for > or =6 days, indicating that sustained neutropenia is a risk factor for failure of initial empirical therapy. The rate of response to monotherapy was lower in leukemic patients, whereas the rate of response to dual therapy did not differ between leukemic and nonleukemic groups. The rate of response to either monotherapy or dual therapy did not differ for patients with temperatures of > or =38 degrees C or 37.5 degrees C-38 degrees C. Overall, defervescence occurred in >80% of patients with mild infections, whereas only 32% of those with moderate to severe infection responded by day 3 and 69.8% by day 7.