Developmental patterns in human blood-brain barrier and blood-cerebrospinal fluid barrier ABC drug transporter expression.

When drugs exert their effects in the brain, linear extrapolation of doses from adults could be harmful for children as the blood-brain barrier (BBB) and blood-CSF barrier (BCSFB) function is still immature. More specifically, age-related variation in membrane transporters may impact brain disposition. As human data on brain transporter expression is scarce, age dependent [gestational age (GA), postnatal age (PNA), and postmenstrual age (PMA)] variation in immunohistochemical localization and staining intensity of the ABC transporters P-glycoprotein (Pgp), breast cancer resistance protein (BCRP), and multidrug resistance-associated proteins 1, 2, 4, and 5 (MRP1/2/4/5) was investigated. Post mortem brain cortical and ventricular tissue was derived from 23 fetuses (GA range 12.9-39 weeks), 17 neonates (GA range 24.6-41.3 weeks, PNA range 0.004-3.5 weeks), 8 children (PNA range 0.1-3 years), and 4 adults who died from a wide variety of underlying conditions. In brain cortical BBB, immunostaining increased with age for Pgp and BCRP, while in contrast, MRP1 and MRP2 staining intensity appeared higher in fetuses, neonates, and children, as compared to adults. BCSFB was positively stained for Pgp, MRP1, and MRP2 and appeared stable across age, while BCRP was not detected. MRP4 and MRP5 were not detected in BBB or BCSFB. In conclusion, human BBB and BCSFB ABC membrane transporters show brain location and transporter-specific maturation.

Aspergillus sinusitis in cancer patients.

Paranasal sinusitis occurred in 52 immunosuppressed cancer patients treated over 5 years at the University of Maryland Cancer Center. Twenty-one patients had aspergillus sinusitis; Aspergillus sp, including flavus and niger were directly recovered from sinus in 19 of the 21 infections. Two other patients with sinus involvement and positive nose cultures for Aspergillus flavus or fumigatus and microbiologically documented pulmonary aspergillosis were considered clinically, although not microbiologically, documented. Predisposing factors for aspergillus sinusitis during the 60 days prior to infection diagnosis were granulocyte count less than 500 microliter (mean duration, 42 days versus 14 days for sinusitis of other etiology; P less than 0.001), prolonged hospitalization (mean duration, 22 days versus 14 days for patients with nonfungal sinusitis; P less than 0.001), and prolonged antibiotic therapy (mean duration, 22 days versus 9 days; P less than 0.001). Treatment with amphotericin B was initially successful for 18 of 21 patients; however, 11 of 18 patients had infection recurrence that always developed at time of tumor exacerbation and reinstitution or intensification of chemotherapy. These findings suggest that aspergillus sinusitis in cancer patients is seen in association with prolonged neutropenia and antibiotic therapy, is amenable to therapy, but tends to recur with relapse of malignancy.

Antibiotic synergism and response in gram-negative bacteremia in granulocytopenic cancer patients.

To determine whether antimicrobial synergism affects the outcome of gram-negative bacteremia among profoundly (less than 100/microliter) neutropenic cancer patients, the clinical courses of 75 such patients who received empiric therapy with combination, broad-spectrum antibiotics were analyzed. Twenty-nine of 34 (85 percent) patients whose granulocyte count increased to more than 100/microliter during therapy improved, whereas only 12 of 41 (29 percent) patients with no increase in granulocyte count showed improvement (p = 0.0002). The critical group for further analysis was, therefore, those patients with persistent, profound granulocytopenia. Among these 41 patients, synergism was associated with a substantially better response rate: eight of 18 (44 percent) improved compared with none of 13 in whom synergism was not detected (p = 0.005); presence or absence of synergism could not be assessed for the pathogens isolated from the remaining 10 patients because the organisms were exquisitely susceptible to one of the two antibiotics used. Further evaluation of these persistently neutropenic patients indicated that synergism appeared critical even when the pathogen was susceptible to both antibiotics. Thus, seven of 11 (64 percent) showed response when the two drugs were synergistic in activity, compared with none of six when synergism was not present (p = 0.01). These data again demonstrate the importance of granulocyte recovery to patient response and further indicate that synergistic combinations of antibiotics are indicated for cancer patients with gram-negative bacteremia and persistent, profound granulocytopenia.

A double beta-lactam combination versus an aminoglycoside-containing regimen as empiric antibiotic therapy for febrile granulocytopenic cancer patients.

The double beta-lactam combination of moxalactam plus piperacillin was compared with the aminoglycoside-containing regimen of moxalactam plus amikacin in a prospective, randomized trial of empiric therapy for 302 febrile episodes in granulocytopenic cancer patients. The moxalactam/piperacillin regimen was found to be as effective as the moxalactam/amikacin regimen (70 percent overall responses); responses with moxalactam/piperacillin and moxalactam/amikacin were similar for microbiologically documented infections (24 of 37, 65 percent, versus 20 of 35, 57 percent), for the subgroup with bacteremias (19 of 32 versus 14 of 28), and for clinically documented infections (41 of 58, 71 percent, versus 40 of 48, 83 percent). Responses were similar also for bacteremia in patients with persistent, profound (less than 100/microliter) granulocytopenia. Among profoundly (less than 100/microliter) granulocytopenic patients with gram-negative bacteremia, an increase in the granulocyte count to more than 100/microliter during therapy and a peak bactericidal activity of 1:16 or more (the latter noted in seven of nine moxalactam/piperacillin trials and six of nine moxalactam/amikacin trials) correlated with a favorable clinical response in 85 percent (p less than or equal to 0.00003) and 92 percent (p less than or equal to 0.044), respectively. Although serious side effects were minimal with either regimen, the double beta-lactam combination was associated with significantly less frequent nephrotoxicity (two of 145 versus 12 of 130; p less than or equal to 0.003) and ototoxicity (none of 34 versus seven of 34; p less than or equal to 0.006). The double beta-lactam combination of moxalactam plus piperacillin was found to be as effective as moxalactam plus amikacin but to have significantly less nephro- and ototoxicity.

Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?

It has been suggested that empiric broad-spectrum antibiotics, instituted for fever in the presence of granulocytopenia, should continue to be administered, even when infection is not demonstrable, to those patients who remain persistently febrile and granulocytopenic. Therefore, the consequences of discontinuing antibiotics when the presence of infection is doubted in this setting were evaluated. In 16 (3.7 percent) of 429 episodes of fever and granulocytopenia for which empiric antibiotic therapy was instituted, after approximately four days, persistence of both fever and granulocytopenia was found, and yet infection was prospectively classified at that time as "doubtful." The initial empiric antibiotic regimen was therefore discontinued after a mean of 4.8 (median 5.0) days. Discontinuation of antibiotics proved appropriate for half of the patients; eight patients received no systemic therapeutic antibiotics with no evidence of infection during a period of at least two weeks. The other eight patients had antibacterial antibiotics reinstituted within a mean of 2.4 days; six infections were subsequently demonstrable. Six of these eight patients also required or were believed to require antifungal therapy with intravenous amphotericin B for presumed fungal infections. Patients with relapsed leukemia or lymphoma and those with a likelihood of continued profound granulocytopenia (counts below 100/microliters) or both were the ones who tended to require reinstitution of antibiotics. Discontinuation of antibiotics when infection was considered doubtful despite persistence of both fever and granulocytopenia was, therefore, successful in eight of 16 patients. Reinstitution of antibiotics was required in the eight remaining patients. No definite rule appears to be applicable to all patients.

Dual lumen catheters for angioaccess in patients with leukemia.

Dual lumen long-term indwelling right atrial catheters have been used to improve venous access in adult patients with leukemia. Twenty-eight such catheters have functioned for 1,895 days in 28 patients over the past eight months at the University of Maryland Hospital. Although insertion of the dual lumen catheter was more technically demanding than insertion of a single lumen catheter, the greater versatility in drug management (e.g., administration of two continuous infusions simultaneously or one continuous infusion leaving one line for platelets, blood, antibiotics or venous sampling) provided by the extra venous portal of entry more than compensated for any increased operative time (average, 58 vs 39 min/insertion). Eight episodes of bacteremia (0.37/100 patient days) occurred in these patients, but only one of these was associated with an exit site infection: the remainder were secondary to infections remote from the catheter. No catheter was removed as a result of these episodes, nor was any removed for ante mortem mechanical failure. The dual lumen catheter is a safe reliable device for providing angioaccess in patients with leukemia and offers substantially greater flexibility than the single lumen catheter.

Trimethoprim/sulfamethoxazole versus placebo: a double-blind comparison of infection prophylaxis in patients with small cell carcinoma of the lung.

The suppression of pathogenic aerobes and the preservation of anaerobes provides a degree of infection prevention during granulocytopenia. Trimethoprim/sulfamethoxazole (TMP/SMZ) suppresses Enterobacteriaceae and probably maintains colonization resistance through sparing of anaerobes. TMP/SMZ (320/1600 mg/day) treatment was compared to placebo in a double-blind, randomized trial in patients with newly diagnosed small cell carcinoma of the lung during the initial courses of chemotherapy with cyclophosphamide, doxorubicin, and etoposide. Infections were evaluated as microbiologically documented, with or without bacteremia, and clinically documented and were correlated to granulocytopenia. Of the 61 patients evaluated, 32 were given TMP/SMZ and 29 were given placebo; both groups had similar characteristics with regard to disease extent, performance status, age, sex, chemotherapy, and days of granulocytopenia. Incidence of infection at less than 100 granulocytes/microliters was significantly reduced in the TMP/SMZ group (2 infections/100 days) compared to placebo (11 infections/100 days, p = 0.005). Also reduced were the number of bacteremias and the mean proportion of study time on broad-spectrum antibiotics (p less than 0.01). Compared to placebo, TMP/SMZ provided infection prophylaxis without an increase in marrow suppression among patients with small cell carcinoma of the lung receiving intensive chemotherapy.

Selective antimicrobial modulation as prophylaxis against infection during granulocytopenia: trimethoprim-sulfamethoxazole vs. nalidixic acid.

Sixty-two profoundly granulocytopenic patients with acute leukemia undergoing induction chemotherapy were prospectively randomized to receive either trimethoprim-sulfamethoxazole plus nystatin or nalidixic acid plus nystatin for prevention of infection. Patients given trimethoprim-sulfamethoxazole plus nystatin during initial remission induction experienced an increased duration (22.6 vs. 13.6 days) of profound granulocytopenia (less than 100 granulocytes/mm3; P = 0.007). Acquisition of gram-negative bacilli was more frequent among patients treated with nalidixic acid plus nystatin while filamentous fungi were acquired more frequently by patients receiving trimethoprim-sulfamethoxazole plus nystatin (P = 0.05). The median duration of on-study time prior to documentation of first infection was longer for patients receiving trimethoprim-sulfamethoxazole plus nystatin (17 days) than for those receiving nalidixic acid plus nystatin (eight days) (P = 0.0002). Three infection-related deaths occurred among patients receiving nalidixic acid; seven occurred among patients receiving trimethoprim-sulfamethoxazole, five of which were secondary to pneumonia due to Aspergillus flavus. Both of these methods of selective antimicrobial modulation have apparent advantages, but each has disadvantages serious enough to limit their routine use.

A comparative evaluation of two fiberoptic bronchoscopy catheters: the plugged telescoping catheter versus the single sheathed nonplugged catheter.

We prospectively evaluated the ability of the plugged telescoping catheter (PTC) brush and the single sheathed nonplugged catheter brush to provide sterile lower respiratory tract samples during fiberoptic bronchoscopy in 19 noninfected patients with cancer. Both brushes were evaluated, in random order, in each of the 19 patients. The PTC brush and the single sheath brush were sterile in 12 and 5 patients, respectively, and in 7 patients, the PTC brush alone was sterile (p = 0.016, two-sided). Patients were anesthetized by lidocaine administered through the bronchoscope (6 patients), via an aerosol (3 patients), or by transtracheal injection (10 patients). The advantage of the PTC brush was evident only when aerosol or transtracheal anesthesia were used; the PTC brush was sterile in 9 of 13 patients, whereas the single sheathed brush was sterile in only 2 of these 13 (p = 0.016, two-sided). The plugged telescoping catheter brush is therefore more suitable than the single sheathed brush catheter for delivering sterile brushes to the lower respiratory tract during fiberoptic bronchoscopy.

Long-term amikacin use. Effects on aminoglycoside susceptibility patterns of gram-negative bacilli.

Amikacin sulfate was first used sparingly at our cancer center in 1976; since 1979, it has been the only aminoglycoside used for systemic cancer therapy for patients with granulocytopenia. As the development of resistance has been correlated with antibiotic use over time, we wished to determine if prolonged use of amikacin in our patients had led to increased amikacin resistance. A total of 1,129 strains were recovered from 315 patients during a 13-month period. Each species isolated per patient was considered once. Seven percent of the patients had amikacin-resistant strains (2.7% of isolates), and 10% of patients had gentamicin-resistant strains (4% of isolates). Amikacin resistance was significantly less than in an earlier study. Unrestricted use of amikacin has not led to a concomitant increase in amikacin resistance in gram-negative bacilli.

Empiric antibiotic therapy for suspected infection in granulocytopenic cancer patients: a comparison between the combination of moxalactam plus amikacin and ticarcillin plus amikacin.

Moxalactam is a new cephalosporin with a broad spectrum of activity which includes Pseudomonas aeruginosa in addition to Klebsiella species Escherichia coli, and Staphylococcus aureus. Moxalactam was combined with amikacin (M + A) compared to ticarcillin plus amikacin (T + A) in a prospective, randomized double-blind trial of empiric therapy for febrile episodes among granulocytopenic cancer patients. One hundred and ninety-one epidoses were evaluated; T + A, 93 episodes and M + A, 98 episodes. Median granulocyte count of initiation of therapy was less than 100/microliters. Overall response rates were good. In the T + A group, 21 of 29 (72 percent) microbiologically documented infections, including seven of 14 (50 percent) bacteremias, and 24 of 27 (89 percent) clinically documented infections improved. In the M + A group, 20 of 28 (71 percent) microbiologically documented infections, including 11 of 18 (61 percent) bacteremias, and 25 of 25 (96 percent) clinically documented infections resolved. Adverse effects were minimal and equivalent in both groups. Hypokalemia (decrease in serum potassium of greater than 11 mEq/liter from baseline) occurred in 14 of the 93 episodes in the T + A group and in 10 of the 98 episodes in the M + A group with decline in mean serum potassium level of 0.5 and 0.4 mEq/liter respectively. Nephrotoxicity (increase in serum creatinine greater than 0.04 mg/dl) occurred in only one patient in the T + A group and in two patients in the M + A group. Moxalactam plus amikacin has a broader in vitro spectrum, is as effective, and is no more toxic than ticarcillin plus amikacin as empiric therapy for febrile granulocytopenic cancer patients.