Vancomycin-arginine (STM-001) abrogates ESBL carrier and carbapenem-resistant Escherichia coli burden in a murine complicated urinary tract infection model.

OBJECTIVES: STM-001, a retargeted glycopeptide, is active against MDR E. coli expressing ESBLs including carbapenemases. Herein, we assessed its capability to combat E. coli complicated urinary tract infections (cUTI) in mice driven by clinically important serine (CTX-M-15) and metallo-ß-lactamases (NDM-1). METHODS: Plasma and urine pharmacokinetics following IV administration of STM-001 (1-50 mg/kg) were determined in mice via LC-MS/MS. The effects on bacterial burden (kidney, bladder and urine) were determined in a 7 day mouse cUTI model whereby STM-001 was administered q12h or q24h at 2-100 mg/kg/day from Day 4. Efficacy was assessed by the change in log10 cfu/g or log10 cfu/mL from vehicle-treated infected mice. RESULTS: MICs of STM-001 for CTX-M-15 and NDM-1 E. coli were 8 and 16 mg/L, respectively. Blood pharmacokinetic profile was linear and dose-dependent with low clearance of 9.49 ±â€Š0.31 mL/min/kg, V = 0.63 ±â€Š0.02 L/kg and t½â€Š= 1.16 ±â€Š0.03 h. High STM-001 concentrations were recovered in urine 0-8 h post-administration, reaching up to 120-fold above its MIC. In cUTI efficacy studies, STM-001 (1-50 mg/kg, q12h) reduced CTX-M-15 burden by log10 4.31 (kidney), 3.95 (bladder) and 4.82 (urine) compared with vehicle-treated animals (P < 0.0001). STM-001 also reduced NDM-1 burden by log10 3.89 (kidney), 3.76 (bladder) and 3.08 (urine) (P < 0.0001), with similar inhibitory effects following q24h dosing. CONCLUSIONS: STM-001 was highly effective in reducing E. coli burden in kidney, bladder and urine in mouse cUTI models. The observed efficacy with either dosing regimen indicates potential low humanized doses of 1-5 mg/kg. These data support further development of STM-001 as an innovative, carbapenem-sparing antibiotic to combat human cUTIs.

In Vivo Targeting of Escherichia coli with Vancomycin-Arginine.

The ability of vancomycin-arginine (V-r) to extend the spectrum of activity of glycopeptides to Gram-negative bacteria was investigated. Its MIC towards Escherichia coli, including ß-lactamase expressing Ambler classes A, B, and D, was 8 to 16 µg/ml. Addition of 8 times the MIC of V-r to E. coli was acutely bactericidal and associated with a low frequency of resistance (<2.32 × 10-10). In vivo, V-r markedly reduced E. coli burden by >7 log10 CFU/g in a thigh muscle model. These data warrant further development of V-r in combatting E. coli, including resistant forms.

Response of Symptomatic Persistent Chronic Disseminated Candidiasis to Corticosteroid Therapy in Immunosuppressed Pediatric Patients: Case Study and Review of the Literature.

BACKGROUND: Chronic disseminated candidiasis (CDC) is a severe invasive fungal infection principally observed during neutrophil recovery in patients with acute leukemia treated with intensive chemotherapy. Its pathophysiology remains unclear. We describe the management of 6 children with symptomatic CDC who did not respond to antifungal therapy. METHODS: The databases of the hematology-oncology departments of 2 tertiary pediatric medical centers were searched for all patients diagnosed with CDC from 2003 to 2015, who responded to corticosteroids after failing antifungal therapy. Clinical, laboratory and radiologic data were collected. RESULTS: Six patients (3 women, 3 men; 9-18 years of age) met the study criteria. Underlying diseases were acute lymphoblastic leukemia (n = 3) and large B-cell lymphoma, acute myeloid leukemia and severe aplastic anemia (n = 1 each). Presenting symptoms/signs of CDC were fever in all cases, with abdominal or chest pain, and/or mucositis. Candida infection was identified in blood cultures in 4 patients and in bronchoalveolar lavage fluid in one. In the absence of response to antifungal agents (4-50 days from CDC diagnosis), prednisone 2 mg/kg/day or equivalent was administered. CDC-attributable clinical symptoms resolved in 4 patients within 6-19 days; one patient required an additional nonsteroidal anti-inflammatory agent. Abnormalities on imaging decreased or disappeared within 5 months to 2 years in 4 patients. CONCLUSIONS: In children with persistent symptomatic CDC, despite adequate antifungal therapy, administration of corticosteroids may yield rapid resolution of symptoms and decreased inflammatory markers. In patients who do not respond to steroids, the addition of a nonsteroidal anti-inflammatory drug should be considered.

Oral Administration of OKT3 MAb to Patients with NASH, Promotes Regulatory T-cell Induction, and Alleviates Insulin Resistance: Results of a Phase IIa Blinded Placebo-Controlled Trial.

UNLABELLED: Oral administration of anti-CD3 antibodies induced regulatory T cells (Tregs) alleviating the insulin resistance and liver damage in animal models. OBJECTIVE: To determine the safety and biological effects of oral OKT3 monoclonal antibody (Balashov et al. Neurology 55:192-8, 2000) in patients with NASH. DESIGN: In this Phase-IIa trial, four groups of patients with biopsy-proven NASH (n = 9/group) received placebo (group A) or oral OKT3 (group B: 0.2; C: 1.0; D: 5.0 mg/day) for 30 days. Patients were followed for safety, liver enzymes, glucose, lipid profile, oral glucose tolerance test (OGTT), serum cytokines and Tregs. RESULTS: Oral OKT3 was well tolerated without treatment-related adverse events. OKT3 induced Tregs: with significant increases of CD4(+)LAP(+) (Latency associated peptide) and CD4(+)CD25(+)LAP(+) cells in Group D, and a significant increase in TGF-ß in Groups C and D. AST decreased significantly in group D and a trend in Groups B and C. Fasting plasma glucose decreased significantly in all treatment groups compared with placebo. OGTT decreased significantly in Group D. Correlations were observed between the changes in several immune-modulatory effects and clinical biomarkers. While serum anti-CD3 levels where undetectable increases in human anti-mouse antibody levels were observed in Groups C and D. CONCLUSION: Oral administration of anti-CD3 MAb to patients with NASH was safe and well tolerated. Positive biological effects were noted in several hepatic, metabolic and immunologic parameters. These findings provide the basis for future trials to investigate the effect of oral anti-CD3 MAb immunotherapy in patients with NASH.

Targeted fluconazole prophylaxis for high-risk very low birth weight infants.

Antifungal prophylaxis is increasingly used in very low birth weight (VLBW) infants who are at risk for severe fungal infections. Our objective was to assess the effectiveness of targeted fluconazole prophylaxis for high-risk VLBW infants. A retrospective cohort study with historical controls was performed. During the period 2007-2008, all high-risk VLBW infants (birth weight, ≤1,000 g; gestational age, ≤28 weeks; seven antimicrobial therapy or additional risk factors present) received fluconazole prophylaxis until risk factors were not present. Treated infants were compared to a gestational age- and birth weight-matched untreated cohort. Statistical analyses used univariate and multivariate analyses. The main outcome variable was a breakthrough fungal bloodstream infection (BSI). The prophylaxis cohort of 130 VLBW infants was compared to 319 control infants. The rate of fungal infections was significantly lower in the fluconazole prophylaxis group (1 of 130 vs. 19 of 319, p = 0.016); however, they did not differ in mortality (16.2 vs. 15 %, p = 0.77) or complications of prematurity. Fluconazole prophylaxis was associated with a significant decrease in candidal BSI (odds ratio, 0.05; 95 % confidence interval, 0.005-0.523). Selective vs. nonselective prophylaxis reduced the number of infants treated from 247 to 130. Conclusion Targeted fluconazole prophylaxis in VLBW infants is effective in preventing fungal infections without increasing the risk of BSI among low-risk infants.

Transcriptional and proteomic analysis of the Aspergillus fumigatus ΔprtT protease-deficient mutant.

Aspergillus fumigatus is the most common opportunistic mold pathogen of humans, infecting immunocompromised patients. The fungus invades the lungs and other organs, causing severe damage. Penetration of the pulmonary epithelium is a key step in the infectious process. A. fumigatus produces extracellular proteases to degrade the host structural barriers. The A. fumigatus transcription factor PrtT controls the expression of multiple secreted proteases. PrtT shows similarity to the fungal Gal4-type Zn(2)-Cys(6) DNA-binding domain of several transcription factors. In this work, we further investigate the function of this transcription factor by performing a transcriptional and a proteomic analysis of the ΔprtT mutant. Unexpectedly, microarray analysis revealed that in addition to the expected decrease in protease expression, expression of genes involved in iron uptake and ergosterol synthesis was dramatically decreased in the ΔprtT mutant. A second finding of interest is that deletion of prtT resulted in the upregulation of four secondary metabolite clusters, including genes for the biosynthesis of toxic pseurotin A. Proteomic analysis identified reduced levels of three secreted proteases (ALP1 protease, TppA, AFUA_2G01250) and increased levels of three secreted polysaccharide-degrading enzymes in the ΔprtT mutant possibly in response to its inability to derive sufficient nourishment from protein breakdown. This report highlights the complexity of gene regulation by PrtT, and suggests a potential novel link between the regulation of protease secretion and the control of iron uptake, ergosterol biosynthesis and secondary metabolite production in A. fumigatus.

Antibiotic exposure as a risk factor for fluconazole-resistant Candida bloodstream infection.

Recent exposure to azoles is an important risk factor for infection with fluconazole-resistant Candida spp., but little is known about the role of antibacterial drug exposure in the emergence of drug-resistant Candida. We did a prospective nationwide surveillance study of candidemia in Israel and analyzed the propensity score-adjusted association between antifungal and antibacterial drug exposure and bloodstream infection with C. glabrata and fluconazole-resistant Candida isolates. Four hundred forty-four episodes of candidemia (450 Candida isolates, 69 [15%] C. glabrata isolates, and 38 [8.5%] fluconazole-resistant isolates) from 18 medical centers in Israel were included. C. glabrata bloodstream infection was strongly associated with recent metronidazole exposure (odds ratio [OR], 3.2; P < 0.001). Infection with a fluconazole-resistant isolate was associated with exposure to carbapenems, trimethoprim-sulfamethoxazole, clindamycin, and colistin (odds ratio, 2.8; P = 0.01). The inclusion of antibacterial drug exposure in a multivariable model significantly enhanced the model's predictive accuracy for fluconazole-resistant Candida bloodstream infection. Our findings may be relevant to the selection of empirical antifungal treatment and broaden the scope of antibiotic-associated collateral damage.

Inducible clindamycin resistance among methicillin-sensitive Staphylococcus aureus infections in pediatric patients.

BACKGROUND: Staphylococcus aureus infections are a major cause of morbidity and mortality worldwide. Clindamycin is widely used in the treatment of staphylococcal infections; however, it is our impression that in the last few years, inducible clindamycin resistance (ICR) has become more prevalent. OBJECTIVE: To assess the prevalence of ICR in methicillin-sensitive Staphylococcus aureus (MSSA) infections among pediatric patients in Israel. METHODS: We reviewed the files of children diagnosed with MSSA infections during the period January 2006 to June 2007 forfull antibiogram (includingthe D-test for ICR), phage typing and randomly amplified polymorphic DNA. RESULTS: Altogether, 240 MSSA isolates were recovered, mainly from wounds and abscesses. ICR was detected in 62 of 68 erythromycin-resistant/clindamycin-sensitive strains (91%); the ICR rate for the total number of isolates was 26% (62/240). Phage type analysis demonstrated that 38 of 61 ICR isolates (62%) were sensitive to group 2, compared to 42 of 172 isolates (24%) that did not express ICR (P < 0.01). On randomly amplified polymorphic DNA, phage type 2 isolates expressing ICR belonged to the same clone, which was different from ICR isolates sensitive to other phages and from isolates not expressing ICR. CONCLUSIONS: Inducible clindamycin resistance is common among methicillin-sensitive Staphylococcus aureus in Israeli children. The D-test should be performed routinely in all MSSA isolates.

BK-virus-associated hemorrhagic cystitis in children after hematopoietic stem cell transplantation.

BACKGROUND: BK-virus-induced hemorrhagic cystitis (BK-HC) is a serious complication in children undergoing hematopoietic stem cell transplantation (HSCT). Data of BK-HC in children undergoing HSCT are still limited. AIM OF THE STUDY: To describe the epidemiology, clinical course, and outcome of children with BK-HC after HSCT. MATERIALS AND METHODS: The medical records of all children aged 0 to 20 years, who underwent HSCT at Schneider Children's Medical Center between 2000 and 2008 and were diagnosed with BK-HC, were reviewed for demographic, clinical, and microbiological data. Patients in whom BK-HC had developed were compared with patients in whom it did not. RESULTS: Seventeen children (5.3%) acquired BK-HC at 10 to 180 days after HSCT (mean, 57 d); 9 had grade 3 to 4 disease. Bleeding lasted for 4 to 42 days (mean, 14). All patients but 1, who died of unrelated causes, recovered. Follow-up ranged from 6 to 91 months (mean, 35 months). Acute myeloid leukemia, use of cyclophosphamide in the conditioning regimen, unrelated donor, and older age were associated with the development of hemorrhagic cystitis (HC). CONCLUSIONS: The incidence of BK-HC in children after HSCT is relatively low. Its rate of successful resolution is very high. Further prospective studies are required to determine optimal therapy.

Containment of a country-wide outbreak of carbapenem-resistant Klebsiella pneumoniae in Israeli hospitals via a nationally implemented intervention.

BACKGROUND: During 2006, Israeli hospitals faced a clonal outbreak of carbapenem-resistant Klebsiella pneumoniae that was not controlled by local measures. A nationwide intervention was launched to contain the outbreak and to introduce a strategy to control future dissemination of antibiotic-resistant bacteria in hospitals. METHODS: In March 2007, the Ministry of Health issued guidelines mandating physical separation of hospitalized carriers of carbapenem-resistant Enterobacteriaceae (CRE) and dedicated staffing and appointed a professional task force charged with containment. The task force paid site visits at acute-care hospitals, evaluated infection-control policies and laboratory methods, supervised adherence to the guidelines via daily census reports on carriers and their conditions of isolation, provided daily feedback on performance to hospital directors, and intervened additionally when necessary. The initial intervention period was 1 April 2007-31 May 2008. The primary outcome measure was incidence of clinically diagnosed nosocomial CRE cases. RESULTS: By 31 March 2007, 1275 patients were affected in 27 hospitals (175 cases per 1 million population). Prior to the intervention, the monthly incidence of nosocomial CRE was 55.5 cases per 100,000 patient-days. With the intervention, the continuous increase in the incidence of CRE acquisition was halted, and by May 2008, the number of new monthly cases was reduced to 11.7 cases per 100,000 patient-days (P<.001). There was a direct correlation between compliance with isolation guidelines and success in containment of transmission (P=.02). Compliance neutralized the effect of carrier prevalence on new incidence (P=.03). CONCLUSIONS: A centrally coordinated intervention succeeded in containing a nationwide CRE outbreak after local measures failed. The intervention demonstrates the importance of strategic planning and national oversight in combating antimicrobial resistance.

Moxifloxacin enhances etoposide-induced cytotoxic, apoptotic and anti-topoisomerase II effects in a human colon carcinoma cell line.

Etoposide (VP-16) is a topoisomerase-II (topo II) inhibitor chemotherapeutic agent. Studies have shown that a combination of VP-16 with other drugs demonstrates better clinical responses. The aim of this study was to investigate the effects of moxifloxacin (MXF) and VP-16 on cellular topo II activity in drug-treated cells and evaluate the influence of MXF on the mode of action of VP-16, on proliferation and apoptosis of HT-29 cells. Decatenation assay, band depletion and Western blot analysis, cytotoxic assay (MTT), flow cytometric studies (cell cycle and survivin expression), apoptosis (DAPI-sulforhodamine staining and caspase 3 activity) and IL-8 and VEGF secretion were determined. MXF or VP-16 slightly affected cellular topo II activity in nuclear extracts derived from drug-treated cells while the combination enhanced inhibitory activity and the reduction in band depletion of topo II. VP-16 induced cell cycle arrest at G2/M and the appearance of the subG1 peak which was increased by the addition of MXF. Apoptosis studies (DAPI staining and caspase 3 activity) showed a marked increase in the presence of MXF and VP-16 compared to VP-16 alone. VP-16 induced the release of IL-8, and addition of MXF reduced enhanced release and the spontaneous release of VEGF from the cells. In conclusion, the results suggest that the enhancement in the reduction of topo II activity by the combined MXF/VP-16 treatments was probably due to the increase in the level of the DNA-enzyme cleavable complexes formed by both drugs. The unique combination of MXF/VP-16 may have clinical benefits and a cytotoxic drug 'sparing effect' and should be further studied in vivo.

Moxifloxacin increases anti-tumor and anti-angiogenic activity of irinotecan in human xenograft tumors.

Camptothecins (CPTs) are topoisomerase I inhibitors chemotherapeutic agents used in combination chemotherapy. We showed previously that combination of moxifloxacin (MXF) and CPT induced inhibitory effects on topoisomerase I activity, on proliferation of HT-29 cells in vitro and enhanced apoptosis, compared to CPT alone. Analysis of secretion of the pro-angiogenic factors IL-8 and VEGF showed significant reduction by MXF. Using a murine model of human colon carcinoma xenograft, we compared the effects of MXF/CPT in vitro to MXF/irinotecan combination in vivo. We show that the MXF/CPT inhibitory effects observed in vitro are reflected in the inhibition of the progressive growth of HT-29 cells implanted in SCID mice. Using caliper measurements, Doppler ultrasonography, image analyses and immunohistochemistry of nuclear proteins (Ki-67) and vascular endothelial cells (CD-31) we show that addition of MXF (45mg/kg) to a relatively ineffective dose of irinotecan (20mg/kg), results in a 50% and 30% decrease, respectively, in tumor size and a decrease in Ki-67 staining. Power Doppler Ultrasound showed a significant, pronounced decrease in the number of blood vessels, as did CD-31 staining, indicating decreased blood flow in tumors in mice treated with MXF alone or MXF/irinotecan compared to irinotecan. These results suggest that the combination of MXF/irinotecan may result in enhanced anti-neoplastic/anti-angiogenic activity.

Infectious complications of peripherally inserted central venous catheters in children.

BACKGROUND: Peripherally inserted central venous catheters (PICCs) are frequently used in infants and children. However, only limited data are available on current infectious and noninfectious complications of PICCs in this patient population. The aim of the study is to define the current rate of infectious and noninfectious complications of PICCs, the causative agents, and to define possible risk factors associated with these complications. METHODS: A prospective surveillance study was conducted at the Schneider Children Medical Center of Israel. All patients in whom a PICC was inserted between August 2004 and October 2006 were included. Demographic, clinical, and microbiologic data were collected by a questionnaire completed by the anesthesiologist at the time of insertion and removal of each catheter. Items covered epidemiologic, clinical, and microbiologic data. RESULTS: A total of 279 PICCs were inserted in 221 patients. There were no complications at insertion. Mean dwell time was 30 days. One hundred seventy-seven (63%) of all PICC placements were free of complications. Twenty-six catheters (9.3%) were dislodged accidentally; 38 (13.6%) were removed for mechanical problems: tears in 5, leaks in 12, and obstructions in 21; 38 (13.6%) were removed for an infectious complication: phlebitis in 13 (4.6%, 1.5/1000 PICC days), exit-site infection in 10 (3.5%, 1.1/1000 PICC days), PICC-associated bloodstream infection in 12 (4.3%, 1.4/1000 PICC days), and PICC-related bloodstream infection in 4 (1.4%, 0.4/1000 PICC days); 15 more were removed for presumed infection (5.3%, 1.7/1000 PICC days). On multivariate analysis, composite indication for PICC use and older patient age were significantly associated with infectious complications. CONCLUSIONS: PICCs are safe and may be used for prolonged periods. In our center, the rates of infectious complications are lower than for tunneled central venous catheters. Accidental dislodgement is not uncommon and may be prevented by use of sutures, occlusive dressing, and education of patients, families, and medical staff.

Identification of novel cell wall destabilizing antifungal compounds using a conditional Aspergillus nidulans protein kinase C mutant.

OBJECTIVES: Despite the need for novel drugs to combat fungal infections, antifungal drug discovery is currently limited by both the availability of suitable drug targets and assays to screen corresponding targets. The aim of this study was to screen a library of small chemical compounds to identify cell wall inhibitors using a conditional protein kinase C (PKC)-expressing strain of Aspergillus nidulans. This mutant is specifically susceptible to cell wall damaging compounds under PKC-repressive growth conditions. METHODS: The inhibitory effect of a library of small chemical compounds was examined in vitro using the conditional A. nidulans PKC strain and a panel of pathogenic fungal isolates. Microscopy was used to assess alterations to fungal ultrastructure following treatment. RESULTS: Three 'hit' compounds affecting cell wall integrity were identified from a screen of 5000 small chemical compounds. The most potent compound, CW-11, was further characterized and shown to specifically affect cell wall integrity. In clinical isolates of Aspergillus fumigatus, CW-11 induces morphological changes characteristic of damage to the cell wall, including wall thickening and rupturing. Analysis of the susceptibility of A. fumigatus and A. nidulans cell wall and signalling pathway mutants to CW-11 suggests that its mode of action differs from that of the antifungals caspofungin and voriconazole. CONCLUSIONS: This work demonstrates the feasibility of using a conditional Aspergillus mutant to conduct a small-molecule library screen to identify novel 'hit' compounds affecting cell wall integrity.

In vitro synergy of caspofungin with licensed and novel antifungal drugs against clinical isolates of Fusarium spp.

Combinations of caspofungin (CAS) with amphotericin-B (AMB), voriconazole (VRC), terbinafine (TRB) and tacrolimus (FK-506) were tested in vitro with 10 Fusarium isolates. MIC and minimal effective concentrations (MEC) were investigated in accord with the CLSI methodology. Drug interactions were assessed by the fractional inhibitory concentration index (FICI). Synergy occurred in 10/10, 9/10, 7/10 and 4/10 isolates with CAS/FK-506, CAS/TRB, CAS/AMB and CAS/VRC, respectively. Caspofungin MECs reached clinically attainable concentrations with FK-506 and TRB. Hyphal length and DiBAC staining demonstrated enhanced inhibition and killing with CAS/FK-506 and CAS/TRB. The combination of CAS/TRB and CAS/FK-506 is strongly synergistic in vitro against Fusarium spp. Our finding should be further studied in animal models of invasive infections caused by this fungus.

Antibiotic use in 26 departments of internal medicine in 6 general hospitals in Israel: variability and contributing factors.

OBJECTIVES: Increased antibiotic consumption is associated with increased bacterial resistance worldwide. We aimed to analyse antibiotic consumption and potential contributory factors in internal medicine departments in Israel. METHODS: Data (2003-04) from 26 departments in 6 hospitals were retrieved. Defined daily doses (DDD)/100 bed-days were calculated for total antibiotic use and by antibiotic class. Patterns identified were correlated with 15 patients' and departmental variables by univariate and multivariate analyses. RESULTS: Total antibiotic consumption differed by a factor of 2.3 (115 DDD/100 bed-days to 49.1 DDD/100 bed-days) between the highest and lowest consuming departments. Antibiotic classes differed by a factor of 22.8 for macrolides, a factor of 20 for piperacillin/tazobactam, a factor of 17 for carbapenems, a factor of 13.3 for quinolones, a factor of 9 for vancomycin, a factor of 6.8 for amoxicillin/clavulanate, a factor of 6.6 for aminoglycosides, a factor of 5.3 for penicillins and a factor of 2.8 for cephalosporins. Even among departments within hospitals, there was a difference of up to 1.5-fold for total use and antibiotic class differences ranged between 2.5- and 7.2-fold for third- and fourth-generation cephalosporins, despite similar Charlson scores and other patient variables. In the multivariate analysis, hospital affiliation and rate of 1 day hospitalization were the only significant variables predicting total antibiotic use, contributing 43% and 7.3%, respectively, to the variance. By antibiotic class, controlling for hospital affiliation, patients with neutropenia, lower respiratory tract infections and assisted ventilation were the most common significant contributors, ranging from 3.5% for quinolones to 7.7% for piperacillin/tazobactam. CONCLUSIONS: Patterns of antibiotic use vary widely among internal medicine departments in Israel, which cannot be explained by objective parameters related either to patients or wards. Ongoing monitoring and guideline formulation are needed to regulate antibiotic prescription.

Breakthrough cerebral toxoplasmosis in a patient receiving atovaquone prophylaxis after a hematopoietic stem cell transplantation.

We describe a case of breakthrough cerebral toxoplasmosis during atovaquone therapy in a child who was intolerant of conventional prophylactic regimens after hematopoietic stem cell transplantation. The available data on the efficacy of atovaquone prophylaxis in Toxoplasma sero-positive stem cell transplant recipients remain limited, and other strategies, such as preemptive strategy using toxoplasma PCR or TMP-SMX desensitization should be considered in this setting.

Quinolones as enhancers of camptothecin-induced cytotoxic and anti-topoisomerase I effects.

Camptothecins (CPTs) are topoisomerase I (topo I) inhibitor chemotherapeutic agents. Studies indicate that combination therapy is needed in most therapeutic protocols with camptothecins. Certain fluoroquionolones inhibit topoisomerase II activity in eukaryotic cells. We showed previously that the fluoroquionolone moxifloxacin inhibited purified human topoisomerase II, acted synergistically with etoposide and enhanced anti-proliferative effect in THP-1 and Jurkat cells. There is no information on flouroquionolone's activity on topoisomerase I. We examined the effect of moxifloxacin and ciprofloxacin alone or in combination with camptothecin on purified topoisomerase I activity and further analysed their combined activity on proliferation and apoptosis in HT-29 cells. Moxifloxacin and ciprofloxacin alone slightly inhibited purified topoisomerase I activity; however in combination with camptothecin it led to a 82% and 64% reduction in enzyme activity, respectively. Moreovwer, our studies indicate that incubation of HT-29 cells with a combination of moxifloxacin or ciprofloxacin with CPT increases cellular topoisomerase I inhibitory activity. In cell proliferation assays, addition of moxifloxacin to 1nM camptothecin enhanced its cytotoxic activity by three-fold and was similar to that of 50nM camptothecin alone (45+/-2.1% inhibition). Ciprofloxacin enhanced cytotoxic activity to a lesser extent. Apoptosis studies showed up to 1.6-fold increase in annexin V positive cells when the fluoroquinolones were combined with camptothecin as compared to camptothecin alone. Analysis of the proangiogenic factors IL-8 and VEGF showed significant reduction in IL-8 production by moxifloxacin and ciprofloxacin up to 48% and in VEGF secretion from the cells. Further in vivo and clinical studies of camptothecins combined with the above fluoroquinolones are warranted.

The epidemiology of bacteremia with febrile neutropenia: experience from a single center, 1988-2004.

BACKGROUND: The epidemiology of bacteremic febrile neutropenia differs between locations and constitutes the basis for selection of empiric antibiotic therapy for febrile neutropenia. OBJECTIVES: To describe the epidemiology of bacteremia among patients with neutropenia in a single center in Israel. METHODS: We conducted a prospective data collection on all patients with neutropenia (< 500/mm3) and clinically significant bacteremia or fungemia during the period 1988-2004. RESULTS: Among adults (462 episodes) the most common bloodstream isolate was Escherichia coli. Gram-negative bacteria predominated throughout the study period and the ratio between Gram-negative and Gram-positive bacteremia increased from 1.7 to 2.3. Among children (752 episodes), the ratio between Gram-negative and Gram-positive bacteremia reversed from 1.2 to 0.7, due to increasing prevalence of coagulase-negative staphylcoccal bacteremia. Both among adults and children, the length of hospital stay prior to bacteremia had a major impact on the pathogens causing bacteremia and their antibiotic susceptibilities. The prevalence of E. coli decreased with time in hospital, while the rates of Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter spp., Acinetobacter spp., Enterococcus spp. and Candida spp. increased. Resistance to broad-spectrum empiric monotherapy in our center was observed in > 40% of Gram-negative bacteria when bacteremia was acquired after 14 days in hospital. CONCLUSIONS: Improved infection-control measures for neutropenic cancer patients in our center are needed. Empiric antibiotic treatment should be tailored to patients' risk for multidrug-resistant organisms. Individual hospitals should monitor infection epidemiology among cancer patients to guide empiric antibiotic treatment.