Ciprofloxacin and norfloxacin for selective decontamination in patients with severe granulocytopenia

Infectious complications in patients with myelodysplastic syndromes: A review of the literature with emphasis on patients treated with 5-azacitidine

Myelodysplastic Syndromes are oligo-clonal stem cell disorders that are associated with cytopenias in the peripheral blood. Major causes for morbidity and mortality in myelodysplastic syndromes (MDS) patients are infections mostly due to bacteria or fungi. Beside leucopenia per se in affected patients, function of white blood cells particularly that of neutrophils seems to be impaired. Here we summarize the available data on infections in MDS patients in general and particularly those treated with 5-azacitidine.

The prevention and management of infections due to multidrug resistant organisms in haematology patients

Infections due to resistant and multidrug resistant (MDR) organisms in haematology patients and haematopoietic stem cell transplant recipients are an increasingly complex problem of global concern. We outline the burden of illness and epidemiology of resistant organisms such as gram-negative pathogens, vancomycin-resistant Enterococcus faecium (VRE), and Clostridium difficile in haematology cohorts. Intervention strategies aimed at reducing the impact of these organisms are reviewed: infection prevention programmes, screening and fluoroquinolone prophylaxis. The role of newer therapies (e.g. linezolid, daptomycin and tigecycline) for treatment of resistant and MDR organisms in haematology populations is evaluated, in addition to the mobilization of older agents (e.g. colistin, pristinamycin and fosfomycin) and the potential benefit of combination regimens.

Antibiotic prophylaxis for bacterial infections in afebrile neutropenic patients following chemotherapy

BACKGROUND

Bacterial infections are a major cause of morbidity and mortality in patients who are neutropenic following chemotherapy for malignancy. Trials have shown the efficacy of antibiotic prophylaxis in reducing the incidence of bacterial infections but not in reducing mortality rates. Our systematic review from 2006 also showed a reduction in mortality.

OBJECTIVES

This updated review aimed to evaluate whether there is still a benefit of reduction in mortality when compared to placebo or no intervention.

SEARCH METHODS

We searched the Cochrane Cancer Network Register of Trials (2011), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2011), MEDLINE (1966 to March 2011), EMBASE (1980 to March 2011), abstracts of conference proceedings and the references of identified studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-RCTs comparing different types of antibiotic prophylaxis with placebo or no intervention, or another antibiotic, to prevent bacterial infections in afebrile neutropenic patients.

DATA COLLECTION AND ANALYSIS

Two authors independently appraised the quality of each trial and extracted data from the included trials. Analyses were performed using RevMan 5.1 software.

MAIN RESULTS

One-hundred and nine trials (involving 13,579 patients) that were conducted between the years 1973 to 2010 met the inclusion criteria. When compared with placebo or no intervention, antibiotic prophylaxis significantly reduced the risk of death from all causes (46 trials, 5635 participants; risk ratio (RR) 0.66, 95% CI 0.55 to 0.79) and the risk of infection-related death (43 trials, 5777 participants; RR 0.61, 95% CI 0.48 to 0.77). The estimated number needed to treat (NNT) to prevent one death was 34 (all-cause mortality) and 48 (infection-related mortality).Prophylaxis also significantly reduced the occurrence of fever (54 trials, 6658 participants; RR 0.80, 95% CI 0.74 to 0.87), clinically documented infection (48 trials, 5758 participants; RR 0.65, 95% CI 0.56 to 0.76), microbiologically documented infection (53 trials, 6383 participants; RR 0.51, 95% CI 0.42 to 0.62) and other indicators of infection.There were no significant differences between quinolone prophylaxis and TMP-SMZ prophylaxis with regard to death from all causes or infection, however, quinolone prophylaxis was associated with fewer side effects leading to discontinuation (seven trials, 850 participants; RR 0.37, 95% CI 0.16 to 0.87) and less resistance to the drugs thereafter (six trials, 366 participants; RR 0.45, 95% CI 0.27 to 0.74).

AUTHORS' CONCLUSIONS

Antibiotic prophylaxis in afebrile neutropenic patients significantly reduced all-cause mortality. In our review, the most significant reduction in mortality was observed in trials assessing prophylaxis with quinolones. The benefits of antibiotic prophylaxis outweighed the harm such as adverse effects and the development of resistance since all-cause mortality was reduced. As most trials in our review were of patients with haematologic cancer, we strongly recommend antibiotic prophylaxis for these patients, preferably with a quinolone. Prophylaxis may also be considered for patients with solid tumours or lymphoma.

Defining the role of macrophages in local moxifloxacin tissue concentrations using biopsy data and whole-body physiologically based pharmacokinetic modelling

OBJECTIVES

This study used a whole-body physiologically based pharmacokinetic (WB-PBPK) model for moxifloxacin, plus in vitro and in vivo literature data on its interaction with macrophages, to interpret biopsy results generated from patients undergoing primarily colorectal surgery.

METHODS

A WB-PBPK model was developed using PK-Sim(R) software and refined using observed plasma profiles. The model was assessed by comparing predictions of unbound interstitial concentrations with in vivo data from a microdialysis study.

RESULTS

Incorporating in vitro data on the percentage volume of macrophages in a colorectal resection (8.1%) plus the in vivo kinetic and accumulation potential of moxifloxacin in macrophages into the WB-PBPK model, biopsy concentrations and kinetics were predicted and compared with observed data. The WB-PBPK model accurately described adipose and muscle interstitial unbound concentrations. The predicted biopsy concentrations (including interstitial, intracellular, vascular space and macrophages) were slightly greater than the observed values, although the kinetic (i.e. observed biopsy half-life = 21 hours) was similar to that of moxifloxacin in macrophages (20.8 hours) and thus similar to the predicted biopsy half-life. A reduction in the predicted biopsy concentrations to match the observed data required a decrease in the volume fraction of macrophages from 8.1% to 3.6%.

CONCLUSION

When plasma concentrations are known, WB-PBPK is a method to determine interstitial and intracellular concentrations. In this study, integration of biopsy data with WB-PBPK allowed for generation and testing of hypotheses to determine the reason for the observed biopsy kinetics. This type of translational modelling may lead to a better understanding of the anti-infective pharmacokinetic/pharmacodynamic relationship.

Antibiotic prophylaxis for bacterial infections in afebrile neutropenic patients following chemotherapy

BACKGROUND

Bacterial infections are a major cause of morbidity and mortality in neutropenic patients following chemotherapy for malignancy. Trials have shown the efficacy of antibiotic prophylaxis in decreasing the incidence of bacterial infections, but not in reducing mortality rates.

OBJECTIVES

This review aimed to evaluate whether antibiotic prophylaxis in afebrile neutropenic patients reduced mortality when compared to placebo or no intervention.

SEARCH STRATEGY

Electronic searches on The Cochrane Cancer Network Register of Trials (2004), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2004), MEDLINE (1966 to 2004) and EMBASE (1980 to 2004) and abstracts of conference proceedings; references of identified studies; the first author of each included trial was contacted.

SELECTION CRITERIA

RCTs or quasi-RCTs comparing different types of antibiotic prophylaxis with placebo or no intervention, or another antibiotic to prevent bacterial infections in afebrile neutropenic patients.

DATA COLLECTION AND ANALYSIS

Two authors independently appraised the quality of each trial and extracted data from the included trials. Relative risks (RR) or average differences, with their 95% confidence intervals (CI) were estimated.

MAIN RESULTS

One hundred trials (10,274 patients) performed between the years 1973 to 2004 met inclusion criteria. Antibiotic prophylaxis significantly decreased the risk for death when compared with placebo or no intervention (RR, 0.66 [95% CI 0.54 to 0.81]). The authors estimated the number needed to treat (NNT) in order to prevent 1 death from all causes as 60 (95% CI 34 to 268). Prophylaxis resulted in a significant decrease in the risk of infection-related death, RR 0.58 (95% CI 0.45 to 0.74) and in the occurrence of fever, RR 0.78 (95% CI 0.75 to 0.82). A reduction in mortality was also evident when the more recently conducted quinolone trials were analysed separately. Quinolone prophylaxis reduced the risk for all-cause mortality, RR 0.52 (95% CI, 0.37 to 0.84).

AUTHORS' CONCLUSIONS

Our review demonstrated that prophylaxis significantly reduced all-cause mortality. The most significant reduction in mortality was observed in trials assessing prophylaxis with quinolones. The benefit demonstrated in our review outweighs harm, such as adverse effects, and development of resistance, since all-cause mortality is reduced. Since most trials in our review were of patients with haematologic cancer, prophylaxis, preferably with a quinolone, should be considered for these patients.

Retinal toxicity of liposome-incorporated and free ofloxacin after intravitreal injection in rabbit eyes

BACKGROUND

Ofloxacin (OFLX) is a fluoroquinolone-antibiotic with a broad antimicrobial spectrum that may have a potential role in the treatment of bacterial endophthalmitis. However, its elimination half life after intravitreal injection is short. To prolong the intravitreal antibacterial level OFLX was incorporated into liposomes. This study was performed to investigate the retinal toxicity of liposome-incorporated and free OFLX.

MATERIALS AND METHODS

OFLX was incorporated into multilamellar large vesicles. 0.1 ml of this suspension (= 180.2 microg OFLX) was injected into the midvitreous of rabbit eyes (n = 6). Free OFLX in doses of 100 microg, 500 microg and 1,000 microg was injected into the midvitreous of a second group of rabbit eyes (n = 18). The other eye served as a control and received empty liposomes or normal saline solution, respectively. Before injection and at the end of follow-up an ERG was obtained. After a follow-up of 1 day, 14 and 28 days the animals were perfused with glutaraldehyde and the eyes were examined by light- and transmission electron microscopy.

RESULTS

The ERG as well as the histologic studies did not reveal any pathological changes after injection of liposome-incorporated OFLX compared to the control eyes. Significant reduction of the ERG was observed after 500 microg free OFLX in 2 out of 6 eyes after 1 and 14 days, respectively, and in 2 eyes 1 day after 1,000 microg free OFLX. Three days after injection of 1,000 microg OFLX the retina showed focal destruction in 1 out of 6 eyes. In another eye with the same dose 14 days after injection the photoreceptor outer segments showed disorganisation.

CONCLUSION

This study shows that liposome-incorporated OFLX did not have any retinal toxicity in this animal model. Free OFLX appears to have no retinal toxicity in rabbit eyes at a dose of 100 microg after intravitreal injection. Injection of higher doses resulted in ERG changes and marked retinal damage.

Selective decontamination of the colon before elective colorectal surgery. West of Scotland Surgical Infection Study Group

The controversy over the route of administration of antibiotic prophylaxis in patients undergoing elective colorectal operations persists for oral, parenteral, and a combination of the two routes. The oral antibiotics commonly administered for colorectal prophylaxis, neomycin and eythromycin base, are not absorbed in the gastrointestinal tract (GIT). However, the 4-fluoroquinolones are absorbed in the upper GIT and are excreted in part by the colonic mucosa. Their action is then to remove, or severely depress, the gram-negative aerobic bacilli leaving the anaerobic flora unaffected. This action is the principle of selective decontamination. We have assessed the efficacy of oral ciprofloxacin in a prospective randomized clinical trial in which all patients received piperacillin 4 g i.v. as single-dose parenteral prophylaxis. A group of 327 evaluable patients were randomized to receive ciprofloxacin 500 mg b.i.d. with the preoperative cathartic (group OA, n = 159) or no oral antibiotic (group NOA, n = 168). Postoperative wound infection occurred in 18 (11.3%) patients in group OA and 39 (23.2%) patients in group NOA (chi 2 = 7.2, p = 0.007). Operation-related infection of any type occurred in 23 (14.5%) patients in group OA compared with 55 (32.7%) in group NOA (chi 2 = 14.0, p = 0.0002). The median postoperative hospital stay was 11 days (interquartile range 4.5 days) for group OA and 12 days (interquartile range 8 days) for group NOA (Mann Whitney U test, p = 0.005). Ignoring the treatment group, the median postoperative hospital stay was 17 days (interquartile range 10 days) for infected patients and 11 days (interquartile range 4 days) for those not infected.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteremia due to viridans streptococci in neutropenic patients: a review

Viridans streptococci have long been considered, with the exception of the ability to cause endocarditis, as minor pathogenic agents. More recently, however, these bacteria have become a major concern in neutropenic patients undergoing a chemotherapeutic treatment. In this high-risk population, they can be responsible for up to 39% of bacteremia cases and are the most frequent cause of this type of infection. The most frequently isolated species in blood cultures are Streptococcus mitis and Streptococcus sanguis II. Viridans streptococcus bacteremia can be accompanied by serious complications, like adult respiratory distress syndrome (ARDS) (3% to 33%), shock (7% to 18%) or endocarditis (7% to 8%). Mortality rates range from 6% to 30%. Case-control studies have identified the following risk factors: severe neutropenia (< 100 neutrophils/mm3), prophylactic antibiotic treatments with quinolone or co-trimoxazole, absence of intravenous antibiotics at the time of bacteremia, high doses of cytosine arabinoside, oropharyngeal mucositis, and heavy colonization by viridans streptococci. The introduction of penicillin in prophylactic antibiotic treatments has reduced the incidence of these infections, but the long-term use of penicillin could be compromised by the emergence of resistant strains.

Emergence of fluoroquinolone-resistant Escherichia coli at a cancer center

Prophylactic treatment with fluoroquinolones of patients with profound neutropenia has been found to be useful for preventing gram-negative bacteremia and has become a standard preventive-therapy strategy in many cancer centers, but the development of bacterial resistance is a cause of concern. During the past few years, we have observed an increasing number of patients with leukemia from whom fluoroquinolone-resistant strains of Escherichia coli were isolated. The increase was significant in this patient population, and among patients with other underlying diseases, the rates of isolation of such strains per number of discharges were significantly lower and did not increase. Most of the leukemia case patients (16 of 19) had been pretreated with an oral quinolone (ofloxacin), with cumulative doses until the first isolation of a resistant E. coli strain ranging from 0 to 97.8 g (median, 14.4 g). Repeated isolation of such strains was seen in 8 of 17 patients during a follow-up period of > or = 4 weeks and in 1 of 6 patients during a follow-up period of > or = 16 weeks. Ten patients developed bacteremia (mortality, 1 of 10). On the basis of the number of patients with leukemia admitted to the hematology-oncology service, the incidence of bacteremia caused by fluoroquinolone-resistant E. coli increased from < 0.5% in 1988-1989 and 0.8% in 1990-1991 to 4.5% in 1992-1993 (P < 0.01). MICs for nine isolates obtained from cultures of blood from different patients ranged between 8 and 16 microgram/ml (ciprofloxacin and PD 131628), 8 and 32 microgram/ml (ofloxacin and BAY Y 3118), and 16 and 32 microgram/ml (sparfloxacin) and indicated resistance to trimethoprim-sulfamethoxazole, ampicillin, doxycycline, and chloramphenicol. Of nine isolates obtained from cultures of blood from different patients and that were subjected to genomic DNA typing by pulsed-field gel electrophoresis of XbaI digests, seven were typeable. Among these, four different genotypes were identified, suggesting both the independent development and the horizontal spread of resistant clones of E. coli.

Use of the quinolones for the prophylaxis and therapy of infections in immunocompromised hosts

The prevention and treatment of infections are major issues of supportive care in patients with haematological malignancies. Because of their broad antimicrobial activity, the use of fluoroquinolones for prophylaxis in neutropenic patients has been extensively studied. In comparison with placebo, norfloxacin reduces the incidence of Gram-negative infections, whereas Gram-positive bacterial and fungal infections remain unaffected. Ofloxacin and enoxacin also bacterial and fungal infections remain unaffected. Ofloxacin and enoxacin also produce a reduction in fever and documented infections. In randomized studies comparing ciprofloxacin with cotrimoxazole (trimethoprim/sulfamethoxazole) plus colistin (each in combination with nonabsorbable antifungal agents), conflicting results were obtained. The incidence of documented Gram-negative bacterial infections was markedly reduced by ciprofloxacin prophylaxis; however, the number of Gram-positive infections may increase dramatically. Combining ciprofloxacin with a macrolide antibiotic in an attempt to prevent streptococcal infections can result in breakthrough bacteraemias due to resistant Gram-positive pathogens. Empirical antimicrobial therapy after quinolone prophylaxis should also be directed against microorganisms susceptible to quinolones, since sustained eradication by oral administration cannot be assumed with certainty. Clinical trials comparing intravenous quinolones in combination with aminoglycosides with widely used standard regimens for the treatment of infections in cancer patients indicate equivalent efficacy; however, in studies of ciprofloxacin alone, response rates were significantly lower compared with standard combinations. Therefore, quinolone monotherapy as empirical treatment in febrile neutropenic patients cannot be recommended.

Failure of clindamycin to influence the course of severe oromucositis associated with streptococcal bacteraemia in allogeneic bone marrow transplant recipients

33 consecutive allogeneic bone marrow transplant recipients who were likely to develop streptococcal bacteraemia were treated for 5 days with clindamycin (900 mg i.v. t.d.s) and ceftazidime (2 g t.d.s.) for the initial management of fever associated with severe oral mucositis. Bacteraemia due to 'viridans' streptococci was encountered in 23 cases (70%) as mucositis progressed to peak severity and occurred a day before fever in 8 cases. At the end of treatment with clindamycin only 2 patients had defervesced although the streptococci were successfully eradicated. C-reactive protein (CRP) levels continued to rise in 18 cases and declined by more than 10% in only 7 cases. Severe oromucositis rather than infection appeared to induce an acute phase response with fever suggesting bacteraemia due to 'viridans' streptococci to have been a consequence of mucosal damage. Indeed, oromucositis was the only primary focus of inflammation in 22 patients and only after its resolution did both fever and CRP levels diminish. By then, patients had also begun to recover from granulocytopenia. These data indicate that rather than including a specific antimicrobial like clindamycin in an empirical regimen, it would be more beneficial to evolve strategies that minimise mucosal damage in this patient population.

The new fluorinated quinolones for antimicrobial prophylaxis in neutropenic cancer patients

Fluoroquinolones are the most attractive agents for prophylactic use in neutropenic cancer patients, due to their broad antimicrobial spectrum, high concentration in the faeces, systemic bactericidal activity, uncommon emergence of resistant strains and good tolerability. They have proved to be more effective than placebo, oral non-absorbable antibiotics or cotrimoxazole in the prevention of Gram-negative infections. In a prospective, randomised multicentre study performed by the GIMEMA infection program, ciprofloxacin was demonstrated to be more effective than norfloxacin for the reduction of febrile episodes, use of systemic antibiotics, and Gram-negative infections in neutropenic patients with haematological malignancies. The greater efficacy may be related to its better systemic or greater antibacterial activity. The potential problems related to the prophylactic use of fluoroquinolones are the increasing prevalence of Gram-positive infections caused by streptococci and coagulase-negative staphylococci; the reported emergence and nosocomial spread of resistant strains, especially among coagulase-negative staphylococci; the lack of their usefulness as empirical therapy in febrile neutropenic patients. Fluoroquinolones are today the better choice for preventing Gram-negative infections in neutropenic patients and ciprofloxacin should probably be preferred. More information on their efficacy and their relationship to the overall susceptibility of micro-organisms in patients with cancer would be valuable, and careful monitoring of patients treated with these drugs is therefore warranted.

Selective decontamination in bone marrow transplant recipients

Patients undergoing bone marrow transplantation become immunocompromised for various reasons. Deep granulocytopenia, induced by conditioning (chemotherapy and total body irradiation), renders the patient at risk for serious bacterial and fungal infections. Our strategy for prevention of these infections by selective decontamination (SD) is the result of more than 15 years of clinical experience and research. The combination of antibiotics, used as standard SD (neomycin, polymyxin B, pipemidic acid and amphotericin B), with the application of local antimicrobial agents eliminates aerobic Gram-negative rods, Staphylococcus aureus and Candida spp. from the mucosal surfaces of the digestive tract, while the majority of the anaerobic flora persist and support colonization resistance (CR). The antibiotics used either are not resorbed or do not yield therapeutic serum concentrations. Antibiotics which induce therapeutic serum concentrations, such as ciprofloxacin and cotrimoxazole, are only used for SD on a limited scale. When Gram-negative rods persist despite intake of the standard regimen, ciprofloxacin is given until these persisting rods are eliminated. If the patients cannot swallow the oral regimen, i.v. cotrimoxazole is given temporarily. Streptococcal infections are prevented by the i.v. administration of penicillin for 14 days starting on the first day after cytotoxic treatment (conditioning for bone marrow transplantation). The combination of SD and systemic prophylaxis has been shown to be adequate; the major problem then remaining is a relatively mild catheter-associated infection with coagulase-negative staphylococci.

Selective decontamination in neutropenic patients

It is well known that severe neutropenia, as usually seen in patients with acute leukaemia, aplastic anaemia or secondary to aggressive chemotherapy, predisposes to infections with Gram-negative enteric bacilli,Pseudomonas aeruginosa, Staphylococcus aureus, and to fungal infections. Infection with anaerobes, in contrast, is rare in patients with haematologic malignancy [1]. The spectrum of bacterial pathogens in this patient population has recently broadened, and now includes coagulase-negative staphylococci, viridans group streptococci, and, occasionally, coryneforms and other rather unusual opportunistic organisms. All these microorganisms originate either from the patient's own microflora, especially from the digestive tract, or from the hospital environment after having colonized the patient during the hospital stay [2]. Studies have shown that the incidence of fever during periods of severe neutropenia approaches 100%, and most of these fever episodes actually represent bacterial infection. For more than 20 years, methods for the prevention of bacterial and fungal infections have been under investigation in patients with profound neutropenia. These included decontamination trails, oral or systemic antimicrobial prophylaxis, strict reverse isolation and maintenance of germ-free conditions [3–8], prophylactic granulocyte transfusions [9], and, more recently, the application of haemopoietic growth factors [10, 11]. The method which remains the most widely used is oral antimicrobial prophylaxis, especially with agents for so-called selective decontamination of the intestinal tract.

Selective decontamination of the digestive tract in intensive care patients: review and commentary

OBJECTIVE

To evaluate the benefits, risks, and costs of antimicrobial regimens used for selective decontamination of the digestive tract (SDD) in intensive care unit (ICU) patients.

DATA SOURCES

Information was obtained from clinical trials, review articles, abstracts, and textbooks. Key indexing terms included antibiotics, selective decontamination, and infections.

STUDY SELECTION

Research articles describing controlled clinical trials of SDD in medical or surgical ICU patients were reviewed. Trials that investigated transplant, cirrhotic, leukemic, or oncology patient populations were excluded.

DATA EXTRACTION

The details of studies that evaluated nosocomial infection or nosocomial pneumonia rates were extracted. These included study design, demographics, SDD regimens, severity of illness scores, and colonization, infection, and mortality rates.

DATA SYNTHESIS

The use of SDD in mechanically ventilated surgical or trauma ICU patients reduces the incidence of colonization, nosocomial pneumonia, and overall infection rates, but does not change the overall mortality rate. Administration of antibiotic and antifungal agents in a nasogastric suspension is required for SDD. The addition of systemic prophylactic antibiotics or oropharyngeal paste was not required to decrease nosocomial infections. The most frequently studied SDD regimen (colistin/amphotericin B/tobramycin) is not feasible for use in the US because of exorbitant drug costs. Less expensive alternatives include norfloxacin/nystatin, or colistin/nystatin/gentamicin.

CONCLUSIONS

Additional research is required before SDD regimens can be routinely recommended in surgical and trauma ICU patients. A multicenter study is warranted to determine the long-range benefits, potential for resistance, and cost-effectiveness of SDD.

Role of selective decontamination in surgery

Aspects of selective decontamination as an antibiotic prophylaxis in general surgery are discussed with respect to the respiratory tract and wound infection. The high rate of nosocomial infection encountered in surgical patients, who experience up to 71 per cent of all such infection, is considered. The infection rate increases to 70-80 per cent after 1 week in the surgical intensive care unit, while the infection-related mortality rate rises to up to 60 per cent. The endogenous origin of nosocomial infection suggests the importance of maintaining colonization resistance to prevent colonization with Gram-negative micro-organisms, especially using selective decontamination which eliminates potentially pathogenic micro-organisms while leaving colonization resistance intact. Selective decontamination has proved effective in decreasing infection rates by 50-80 per cent, and is especially successful in respiratory tract infection. Possible adverse effects and future indications for selective decontamination are discussed.

Selective oral antimicrobial prophylaxis for the prevention of infection in acute leukaemia-ciprofloxacin versus co-trimoxazole plus colistin. The EORTC-Gnotobiotic Project Group

230 leukaemic patients were entered into a randomised, prospective, multicentre trial of either ciprofloxacin (1 g/day) or co-trimoxazole (1920 mg/day) plus colistin (800 mg/day) for the prevention of infection during granulocytopenia. Bacteraemia due to resistant gram-negative rods occurred only in the co-trimoxazole-colistin group though both regimens were effective for selective gastrointestinal tract decontamination. However, there were fewer patients without any infective complications (31% vs. 18%: P = 0.02), fewer febrile days [mean (S.D.) 5.9 (1.1) vs. 8.2 (1.4): P = 0.0242], a lower proportion of infective events (0.9 (0.16) vs. 1.2 (0.18): P = 0.005) and fever occurred later (median 19 vs. 14 days: 0.025 less than P less than 0.05) in the co-trimoxazole-colistin group. The choice of prophylactic regimen therefore appears to depend upon whether or not protection against gram-negative infection is required or better systemic prophylaxis overall.

Prophylaxis with ofloxacin in patients with cancer and neutropenia

The suppression of potentially pathogenic microorganisms using prophylactic antibacterial treatment could eventually protect the patient from infection. Oral absorbable and non-absorbable antibacterial agents have been used with variable results. In the present study, 47 patients with cancer and neutropenia received oral ofloxacin 200 mg twice daily prophylactically. All patients were previously treated with antineoplastic chemotherapy. Septicemia developed in ten patients (21%). The number of infections was higher in patients with a level of granulocytopenia under 0.5 x 10(9)/1. Infection was caused in almost all patients by gram-positive organisms. Prophylaxis with ofloxacin provided efficacious protection against gram-negative bacteria and was well tolerated.

Protecting neutropenic patients from bowel-derived organisms

Prevention of infection from bowel-derived organisms in neutropenic patients requires both the appropriate use of chemoprophylaxis and close attention to the prevention of cross-colonization or cross-infection with resistant Enterobacteriaceae and pseudomonads. Control of common-source infection and control of Gram-positive infection are also important. The objectives of chemoprophylaxis should be considered and their efficacy regularly assessed. Non-absorbable antibiotics may have an important place in minimizing selection of resistant strains, but absorbed agents such as cotrimoxazole (trimethoprim/sulphamethoxazole) and 4-quinolones offer advantages over these and nalidixic acid as prophylactic agents. Ciprofloxacin prophylaxis is probably more effective at reducing Gram-negative bacteraemia than co-trimoxazole but overall mortality may be higher. Further confirmation and investigation of the reasons for this are needed. Protocols of rational antibiotic prophylaxis and treatment involving these agents can be modified to cover only the Gram-negative superinfections that are likely.

Use of quinolones in the immunocompromised host

Immune deficiency generally leads to infections. Cancer chemotherapy, medical interventions and various investigational procedures are important factors in the development of infection. In recent decades, there has been a major change in most cancer centers in the etiology of bacterial infections occurring in the immunocompromised host, most infections now being caused by gram-positive organisms. This might be partly due to prophylactic use of agents effective against gram-negative bacteria. The quinolones are now widely used in the treatment of serious infections of the immunocompromised patient. Prophylaxis with quinolones is also practised in cancer centers.

Ofloxacin versus trimethoprim-sulfamethoxazole for prevention of infection in patients with acute leukemia and granulocytopenia

In a prospective randomized study we evaluated the efficacy and safety of oral ofloxacin (dosage: 200 mg three times daily) versus trimethoprim-sulfamethoxazole (dosage: 960 mg three times daily) as antibacterial prophylaxis in 128 patients with acute leukemia who received aggressive cytotoxic chemotherapy and were granulocytopenic for a median duration of 30 days. Fewer patients receiving ofloxacin were colonized by Enterobacteriaceae (13% versus 90%, p less than 0.001) and Pseudomonas aeruginosa (3% versus 14%, p = 0.025), and developed gram-negative bacterial infection (4% versus 26%, p = 0.002), whereas the incidence of gram-positive bacterial (19% versus 22%) and fungal (7% versus 14%) infections was similar in both groups. Ofloxacin was significantly better tolerated than trimethoprim-sulfamethoxazole, and shortened the duration of fever (p = 0.02) and of parenteral antimicrobial therapy for presumed or documented acquired infection (p = 0.01). Ofloxacin appears to be a safe, effective, well-tolerated alternative to trimethoprim-sulfamethoxazole for preventing gram-negative infection in acute leukemia, but more effective prophylaxis of gram-positive infections is still needed.

Streptococcal bacteremia in adult patients with leukemia undergoing aggressive chemotherapy. A review of 55 cases

We reviewed 55 cases of streptococcal bacteremia in adult patients who received cytotoxic chemotherapy for treatment of acute leukemia. Viridans group streptococci were the most frequent species isolated (45 isolates). Hemolytic streptococci (four isolates), pneumococci (three isolates), and enterococci (three isolates) were infrequent. Clinical features of streptococcal bacteremia included fever, upper and lower respiratory infection, respiratory distress syndrome, soft tissue infection, and septic shock. Forty patients who had only streptococci, but no other organisms isolated from their blood, were compared with 36 cases of gram-negative bacillary bacteremia that occurred during the same study period within the same population at risk. The comparison showed that patients with streptococcal bacteremia had more often received high dose cytosine arabinoside as part of their chemotherapy (17 vs. five), had a longer mean duration of fever (11 vs. seven days, p less than 0.01) needed slightly more days of antibacterial therapy (15 vs. 12 days, p = 0.07, not significant), and were more likely to have been treated with newer quinolones for infection prevention (30 vs. eight). No differences between both groups were found for age, underlying disease, remission status, duration of severe granulocytopenia, and number of superinfections. The overall mortality was 18% in streptococcal bacteremia and 17% in gram-negative bacillary bacteremia. Streptococci, especially viridans group streptococci, should now be regarded as frequent causes of serious life-threatening infections following aggressive chemotherapy in patients with hematologic malignancies.

Clinical use of selective decontamination: the concept

Infections can be classified according to: (1) the type of offending microorganism (virus, bacteria, fungi, parasites), (2) according to the clearance by the defence system (T cell dependent/independent) and (3) in case bacteria are the causative agents in Gram-positive and Gram-negative infections. The latter classification in Gram-positive and Gram-negative infections has appeared to have a practical consequence. Gram-negative bacteria, often involved in major infections and yeasts, appear to play practically no role in the intestinal ecological system. Consequently, it is nowadays increasingly attempted to eliminate Gram-negative bacteria and yeasts selectively from the digestive tract with antimicrobial agents. Selective suppression of Gram-positive bacteria may severely affect the ecosystem of the digestive tract. This selective suppression of Gram-negatives must be continued as long as patients are immunocompromised (locally or systemically) and is called selective decontamination of the digestive tract.

Prevention of infection in acute leukemia

In a randomized study comparing cotrimoxazole plus colistin with ciprofloxacin, each in combination with nonabsorbable antimycotics, the incidence of major infections in terms of septicemias and pneumonias as well as of minor infections and episodes of unexplained fever (FUO) was higher in patients treated with ciprofloxacin. In cases of microbiologically documented infections, gram-positive cocci dominated by far. In surveillance cultures of oral washings and of feces, gram-negative enterobacteria were only rarely detected; however, large numbers of cultures were positive for Acinetobacter species. There were four cases of documented Pneumocystis carinii pneumonia in patients not receiving cotrimoxazole. The incidence of documented mycotic infections as well as the detection of fungi in surveillance cultures was similar in both treatment groups. A decrease in the number of adverse events, especially of allergic reactions, could not be achieved by the administration of ciprofloxacin. In conclusion, cotrimoxazole plus colistin in combination with nonabsorbable antimycotics remains the standard regimen for prevention of infection in patients with acute leukemia undergoing aggressive remission induction therapy. A detailed analysis of study II will be prepared for publication.

Quinolones and the gastrointestinal tract

A number of studies have evaluated the efficacy of the new fluoroquinolones for therapy of bacterial enteric diseases and for prevention of gram-negative sepsis in granulocytopenic patients. The success of the quinolones in these settings is related to several special features of these agents, including their spectrum of activity and high fecal levels, which are in turn reflected in their effect on the gastrointestinal flora. Other factors that are important, particularly for invasive disease such as typhoid fever and shigellosis, include good intracellular and bowel wall penetration, and lymph node and systemic drug concentrations many times higher than the MICs of the causative organisms. This article reviews the factors that contribute to the changes in fecal flora, and the results of clinical studies in patients with diarrhea, granulocytopenic patients, and patients with selected other infections of, or related to, the gastrointestinal tract.

Effects on oral and intestinal microfloras of norfloxacin and pefloxacin for selective decontamination in bone marrow transplant patients

We monitored the modifications of oral and intestinal microfloras of 10 allogeneic bone marrow recipients who received randomly either norfloxacin or pefloxacin (400 mg three times a day) as selective decontamination for infection prevention. After 1 week of treatment, in all patients members of the family Enterobacteriaceae were no longer detectable and in all but one pefloxacin-treated patient enterococci were also eliminated in the intestine. The anaerobic flora was not affected, with the exception of Bacteroides spp., markedly reduced after treatment with pefloxacin. In most patients the most striking effect was the increase in staphylococcal counts. These strains were found to be resistant to both quinolones in the study. Less consistent changes were observed in oral flora. No relevant difference could be demonstrated between the two regimens on bacterial counts either in feces or in saliva. This study shows the efficacy of both quinolones in eradicating gram-negative bacilli in the alimentary tract of bone marrow transplant patients; however, the finding of the overgrowth of resistant gram-positive organisms during treatment with these agents deserves further evaluation.