Efficacy of sulbactam-ampicillin for the treatment of severe diabetic foot infections

The Epidemiology of Antibiotic-Related Adverse Events in the Treatment of Diabetic Foot Infections: A Narrative Review of the Literature

The use of antibiotics for the treatment of diabetic foot infections (DFIs) over an extended period of time has been shown to be associated with adverse events (AEs), whereas interactions with concomitant patient medications must also be considered. The objective of this narrative review was to summarize the most frequent and most severe AEs reported in prospective trials and observational studies at the global level in DFI. Gastrointestinal intolerances were the most frequent AEs, from 5% to 22% among all therapies; this was more common when prolonged antibiotic administration was combined with oral beta-lactam or clindamycin or a higher dose of tetracyclines. The proportion of symptomatic colitis due to Clostridium difficile was variable depending on the antibiotic used (0.5% to 8%). Noteworthy serious AEs included hepatotoxicity due to beta-lactams (5% to 17%) or quinolones (3%); cytopenia's related to linezolid (5%) and beta-lactams (6%); nausea under rifampicin, and renal failure under cotrimoxazole. Skin rash was found to rarely occur and was commonly associated with the use of penicillins or cotrimoxazole. AEs from prolonged antibiotic use in patients with DFI are costly in terms of longer hospitalization or additional monitoring care and can trigger additional investigations. The best way to prevent AEs is to keep the duration of antibiotic treatment short and with the lowest dose clinically necessary.

Pharmacotherapy of Diabetic Foot Ulcers

The incidence of diabetes and diabetic foot ulcers is increasing significantly in the United States. These ulcers and infections are the result of long-term complications of diabetes including neuropathy and vascular insufficiency. These infections can be classified into mild, limb threatening, and life threatening. This classification helps clarify the expected organisms involved and consequently appropriate, empiric antibiotic therapy. Mild infections are generally caused by Gram-positive organisms and can usually be treated as an outpatient with oral antibiotics. Antibiotics used for mild infections-include cephalexin, clindamycin, and amoxicillin/ clavulanate. Moderate to severe or limb-threatening infections are usually polymicrobial and frequently require hospitalization. These infections are typically treated with more broad-spectrum antibiotics including ampicillin/sulbactam, imipenem, or the combination of clindamycin and a fluoroquinolone. Severe or life-threatening infections also require broad-spectrum antibiotics. Other therapeutic options besides antibiotics include growth factors, such as becaplermin, and various skin substitutes.

Systemic antibiotics for treating diabetic foot infections

BACKGROUND

Foot infection is the most common cause of non-traumatic amputation in people with diabetes. Most diabetic foot infections (DFIs) require systemic antibiotic therapy and the initial choice is usually empirical. Although there are many antibiotics available, uncertainty exists about which is the best for treating DFIs.

OBJECTIVES

To determine the effects and safety of systemic antibiotics in the treatment of DFIs compared with other systemic antibiotics, topical foot care or placebo.

SEARCH METHODS

In April 2015 we searched the Cochrane Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library); Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE, and EBSCO CINAHL. We also searched in the Database of Abstracts of Reviews of Effects (DARE; The Cochrane Library), the Health Technology Assessment database (HTA; The Cochrane Library), the National Health Service Economic Evaluation Database (NHS-EED; The Cochrane Library), unpublished literature in OpenSIGLE and ProQuest Dissertations and on-going trials registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating the effects of systemic antibiotics (oral or parenteral) in people with a DFI. Primary outcomes were clinical resolution of the infection, time to its resolution, complications and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed the risk of bias, and extracted data. Risk ratios (RR) were estimated for dichotomous data and, when sufficient numbers of comparable trials were available, trials were pooled in a meta-analysis.

MAIN RESULTS

We included 20 trials with 3791 participants. Studies were heterogenous in study design, population, antibiotic regimens, and outcomes. We grouped the sixteen different antibiotic agents studied into six categories: 1) anti-pseudomonal penicillins (three trials); 2) broad-spectrum penicillins (one trial); 3) cephalosporins (two trials); 4) carbapenems (four trials); 5) fluoroquinolones (six trials); 6) other antibiotics (four trials).Only 9 of the 20 trials protected against detection bias with blinded outcome assessment. Only one-third of the trials provided enough information to enable a judgement about whether the randomisation sequence was adequately concealed. Eighteen out of 20 trials received funding from pharmaceutical industry-sponsors.The included studies reported the following findings for clinical resolution of infection: there is evidence from one large trial at low risk of bias that patients receiving ertapenem with or without vancomycin are more likely to have resolution of their foot infection than those receiving tigecycline (RR 0.92, 95% confidence interval (CI) 0.85 to 0.99; 955 participants). It is unclear if there is a difference in rates of clinical resolution of infection between: 1) two alternative anti-pseudomonal penicillins (one trial); 2) an anti-pseudomonal penicillin and a broad-spectrum penicillin (one trial) or a carbapenem (one trial); 3) a broad-spectrum penicillin and a second-generation cephalosporin (one trial); 4) cephalosporins and other beta-lactam antibiotics (two trials); 5) carbapenems and anti-pseudomonal penicillins or broad-spectrum penicillins (four trials); 6) fluoroquinolones and anti-pseudomonal penicillins (four trials) or broad-spectrum penicillins (two trials); 7) daptomycin and vancomycin (one trial); 8) linezolid and a combination of aminopenicillins and beta-lactamase inhibitors (one trial); and 9) clindamycin and cephalexin (one trial).Carbapenems combined with anti-pseudomonal agents produced fewer adverse effects than anti-pseudomonal penicillins (RR 0.27, 95% CI 0.09 to 0.84; 1 trial). An additional trial did not find significant differences in the rate of adverse events between a carbapenem alone and an anti-pseudomonal penicillin, but the rate of diarrhoea was lower for participants treated with a carbapenem (RR 0.58, 95% CI 0.36 to 0.93; 1 trial). Daptomycin produced fewer adverse effects than vancomycin or other semi-synthetic penicillins (RR 0.61, 95%CI 0.39 to 0.94; 1 trial). Linezolid produced more adverse effects than ampicillin-sulbactam (RR 2.66; 95% CI 1.49 to 4.73; 1 trial), as did tigecycline compared to ertapenem with or without vancomycin (RR 1.47, 95% CI 1.34 to 1.60; 1 trial). There was no evidence of a difference in safety for the other comparisons.

AUTHORS' CONCLUSIONS

The evidence for the relative effects of different systemic antibiotics for the treatment of foot infections in diabetes is very heterogeneous and generally at unclear or high risk of bias. Consequently it is not clear if any one systemic antibiotic treatment is better than others in resolving infection or in terms of safety. One non-inferiority trial suggested that ertapenem with or without vancomycin is more effective in achieving clinical resolution of infection than tigecycline. Otherwise the relative effects of different antibiotics are unclear. The quality of the evidence is low due to limitations in the design of the included trials and important differences between them in terms of the diversity of antibiotics assessed, duration of treatments, and time points at which outcomes were assessed. Any further studies in this area should have a blinded assessment of outcomes, use standardised criteria to classify severity of infection, define clear outcome measures, and establish the duration of treatment.

Preoperative medical treatment in patients undergoing diabetic foot surgery with a Wagner Grade-3 or higher ulcer: a retrospective analysis of 52 patients

Diabetic foot ulcers (DFU) are one of the most important complications in people with diabetes mellitus. The present study was aimed to retrospectively review the efficacy of at least 1-week medical treatment before any surgical intervention in patients with Grade-3 and higher DFU according to Wagner's classification. A total of 52 patients (36 males and 16 females) hospitalized and treated between June 2006 and February 2009 and had initially received therapeutic treatment (local wound care, antibiotic therapy and blood glucose regulation) for a period of at least 1 week were included in the study. The level of amputation, rates of reulceration and mortality in both groups were recorded in the following period of 2 years. Group 1 (did not respond to preoperative medical intervention) included 16 patients where a surgical debridement, flap or skin graft surgery was performed in 2 (12.5%) patients, major amputation was performed in another 2 (12.5%) patients and minor amputation was performed in the remaining 12 (75%) patients. Of 36 patients in Group 2 (did respond to preoperative medical intervention), 5 (13.9%) patients underwent the surgical debridement, flap or skin graft surgery, 8 (22.2%) patients had a major amputation and the remaining 23 (63.9%) patients lead to a minor amputation. The ulcer recurrence and mortality rates were obtained as 2 (12.5%) and 2 (12.5%) in Group 1 and 2 (5.6%) and 1 (2.8%) in Group 2, respectively. Despite the lower rates of ulcer recurrence and mortality in patients having adequate responses to initial treatment before surgical procedures were performed, no statistically significant difference was observed between the 2 groups. In addition, there was no statistically significant difference between the levels of amputation in both groups.

Systemic antibiotic therapy for chronic osteomyelitis in adults

The standard recommendation for treating chronic osteomyelitis is 6 weeks of parenteral antibiotic therapy. However, oral antibiotics are available that achieve adequate levels in bone, and there are now more published studies of oral than parenteral antibiotic therapy for patients with chronic osteomyelitis. Oral and parenteral therapies achieve similar cure rates; however, oral therapy avoids risks associated with intravenous catheters and is generally less expensive, making it a reasonable choice for osteomyelitis caused by susceptible organisms. Addition of adjunctive rifampin to other antibiotics may improve cure rates. The optimal duration of therapy for chronic osteomyelitis remains uncertain. There is no evidence that antibiotic therapy for >4-6 weeks improves outcomes compared with shorter regimens. In view of concerns about encouraging antibiotic resistance to unnecessarily prolonged treatment, defining the optimal route and duration of antibiotic therapy and the role of surgical debridement in treating chronic osteomyelitis are important, unmet needs.

Risk factors for developing osteomyelitis in patients with diabetic foot wounds

AIMS

Osteomyelitis worsens the prognosis in the diabetic foot, but predisposing factors remain largely undefined. In a prospectively followed cohort we assessed risk factors for developing osteomyelitis.

METHODS

We enrolled consecutive persons with diabetes who presented to a managed-care diabetes disease management program. The patients underwent standardized assessments. We monitored for all foot complications, defined infections by criteria consistent with International Working Group guidelines, and defined osteomyelitis as a positive culture from a bone specimen.

RESULTS

1666 persons were enrolled, 50% male, mean age 69 years. Over a mean of 27.2 months of follow-up, 151 patients developed foot infections, 30 (19.9%) of which involved bone. Independent risk factors for osteomyelitis were: wounds that extended to bone or joint (relative risk [RR]=23.1), previous history of a wound prior to enrollment (RR=2.2), and recurrent or multiple wounds during the study period (RR=1.9).

CONCLUSIONS

In this study population, managed in a specialized diabetic foot care center, the results suggest that independent risk factors for developing osteomyelitis are deep, recurrent and multiple wounds. These results may help clinicians target their efforts at diagnosing foot osteomyelitis to the highest risk patients.

Diabetic foot osteomyelitis: a progress report on diagnosis and a systematic review of treatment

The International Working Group on the Diabetic Foot appointed an expert panel to provide evidence-based guidance on the management of osteomyelitis in the diabetic foot. Initially, the panel formulated a consensus scheme for the diagnosis of diabetic foot osteomyelitis (DFO) for research purposes, and undertook a systematic review of the evidence relating to treatment. The consensus diagnostic scheme was based on expert opinion; the systematic review was based on a search for reports of the effectiveness of treatment for DFO published prior to December 2006. The panel reached consensus on a proposed scheme that assesses the probability of DFO, based on clinical findings and the results of imaging and laboratory investigations. The literature review identified 1168 papers, 19 of which fulfilled criteria for detailed data extraction. No significant differences in outcome were associated with any particular treatment strategy. There was no evidence that surgical debridement of the infected bone is routinely necessary. Culture and sensitivity of isolates from bone biopsy may assist in selecting properly targeted antibiotic regimens, but empirical regimens should include agents active against staphylococci, administered either intravenously or orally (with a highly bioavailable agent). There are no data to support the superiority of any particular route of delivery of systemic antibiotics or to inform the optimal duration of antibiotic therapy. No available evidence supports the use of any adjunctive therapies, such as hyperbaric oxygen, granulocyte-colony stimulating factor or larvae. We have proposed a scheme for diagnosing DFO for research purposes. Data to inform treatment choices in DFO are limited, and further research is urgently needed.

Sulbactam-containing beta-lactamase inhibitor combinations

Sulbactam irreversibly inhibits the hydrolytic activity of beta-lactamases. This compound is commercially available in combination with either ampicillin or cefoperazone. In each instance, the activity of the partner antibiotic against beta-lactamase-producing bacteria is restored. One of the particular advantages of using sulbactam-containing combinations is that sulbactam itself has inherent activity against some Acinetobacter baumannii. Sulbactam combinations have not demonstrated strong selective pressures for extended-spectrum beta-lactamase-producing Enterobacteriaceae and vancomycin-resistant enterococci. In contrast to clavulanate, sulbactam does not induce class I (Ampc) chromosomal beta-lactamases in Enterobacteriaceae.

Diabetes, hand and/or foot ulcers: a cross-sectional hospital-based study in Port Harcourt, Nigeria

OBJECTIVE

The study aimed to establish the prevalence of diabetes mellitus and the pattern of diabetic hand and foot ulcers in hospitalized adult patients in a teaching hospital in Port Harcourt, Nigeria.

RESEARCH DESIGN AND METHODS

All medical admission at the University of Port Harcourt Teaching Hospital between January 2000 and April 2001 were included in this cross-sectional study. Diabetes mellitus was diagnosed based on a fasting venous plasma glucose >or=7.0 mmol/l or a 2-h post-prandial venous plasma glucose level of >or=11.1 mmol/L using the glucose oxidase method. Data was processed for the 60 diabetic patients with limb ulcers excluding ulcers from major trauma.

RESULTS

The prevalence of diabetes mellitus was 38.1% (95% CI=34.8-41.4) among medical in-patients; while hand and foot ulcer was 19.1% among diabetic patients. The left lower limb ranked highest in ulcer involvement (32/60); hand ulcers were found in 5 cases (8.3%). Twenty (33.3%) of the patients had a previous limb ulcer. In 31 patients (51.7%) the ulcers evolved spontaneously without an identifiable cause (p-value=0.00). By Wagner's Grading System, Grade III lesions ranked highest (21/64).

CONCLUSIONS

A high prevalence of hand and foot ulcers was confirmed among patients with diabetics, which are common indications for hospitalization, and usually associated with long hospital stay with adverse outcomes including amputation and death. Diabetes education needs to be stepped-up, with emphasis on foot care and early presentation to hospital in the event of limb ulceration.

Ampicillin/Sulbactam

Ampicillin/sulbactam is a beta-lactam/beta-lactamase inhibitor combination with a broad spectrum of antibacterial activity against Gram-positive, Gram-negative and anaerobic bacteria. Data from comparative studies justify the use of ampicillin/sulbactam in a 2 : 1 ratio in various severe bacterial infections. In comparative clinical trials, ampicillin/sulbactam has proved to be a significant drug in the therapeutic armamentarium for lower respiratory tract infections and aspiration pneumonia, gynaecological/obstetrical infections, intra-abdominal infections, paediatric infections such as acute epiglottitis and periorbital cellulitis, diabetic foot infections, and skin and soft tissue infections. Of particular interest during this era of increasing antimicrobial resistance in various settings and populations is the effectiveness of sulbactam against a considerable proportion of infections due to Acinetobacter baumannii.

Diagnosis and treatment of diabetic foot infections

EXECUTIVE SUMMARY: 1. Foot infections in patients with diabetes cause substantial morbidity and frequent visits to health care professionals and may lead to amputation of a lower extremity. 2. Diabetic foot infections require attention to local (foot) and systemic (metabolic) issues and coordinated management, preferably by a multidisciplinary foot-care team (A-II). The team managing these infections should include, or have ready access to, an infectious diseases specialist or a medical microbiologist (B-II). 3. The major predisposing factor to these infections is foot ulceration, which is usually related to peripheral neuropathy. Peripheral vascular disease and various immunological disturbances play a secondary role. 4. Aerobic Gram-positive cocci (especially Staphylococcus aureus) are the predominant pathogens in diabetic foot infections. Patients who have chronic wounds or who have recently received antibiotic therapy may also be infected with Gram-negative rods, and those with foot ischemia or gangrene may have obligate anaerobic pathogens. 5. Wound infections must be diagnosed clinically on the basis of local (and occasionally systemic) signs and symptoms of inflammation. Laboratory (including microbiological) investigations are of limited use for diagnosing infection, except in cases of osteomyelitis (B-II). 6. Send appropriately obtained specimens for culture before starting empirical antibiotic therapy in all cases of infection, except perhaps those that are mild and previously untreated (B-III). Tissue specimens obtained by biopsy, ulcer curettage, or aspiration are preferable to wound swab specimens (A-I). 7. Imaging studies may help diagnose or better define deep, soft-tissue purulent collections and are usually needed to detect pathological findings in bone. Plain radiography may be adequate in many cases, but MRI (in preference to isotope scanning) is more sensitive and specific, especially for detection of soft-tissue lesions (A-I). 8. Infections should be categorized by their severity on the basis of readily assessable clinical and laboratory features (B-II). Most important among these are the specific tissues involved, the adequacy of arterial perfusion, and the presence of systemic toxicity or metabolic instability. Categorization helps determine the degree of risk to the patient and the limb and, thus, the urgency and venue of management. 9. Available evidence does not support treating clinically uninfected ulcers with antibiotic therapy (D-III). Antibiotic therapy is necessary for virtually all infected wounds, but it is often insufficient without appropriate wound care. 10. Select an empirical antibiotic regimen on the basis of the severity of the infection and the likely etiologic agent(s) (B-II). Therapy aimed solely at aerobic Gram-positive cocci may be sufficient for mild-to-moderate infections in patients who have not recently received antibiotic therapy (A-II). Broad-spectrum empirical therapy is not routinely required but is indicated for severe infections, pending culture results and antibiotic susceptibility data (B-III). Take into consideration any recent antibiotic therapy and local antibiotic susceptibility data, especially the prevalence of methicillin-resistant S. aureus (MRSA) or other resistant organisms. Definitive therapy should be based on both the culture results and susceptibility data and the clinical response to the empirical regimen (C-III). 11. There is only limited evidence with which to make informed choices among the various topical, oral, and parenteral antibiotic agents. Virtually all severe and some moderate infections require parenteral therapy, at least initially (C-III). Highly bioavailable oral antibiotics can be used in most mild and in many moderate infections, including some cases of osteomyelitis (A-II). Topical therapy may be used for some mild superficial infections (B-I). 12. Continue antibiotic therapy until there is evidence that the infection has resolved but not necessarily until a wound has healed. Suggestions for the duration of antibiotic therapy are as follows: for mild infections, 12 weeks usually suffices, but some require an additional 12 weeks; for moderate and severe infections, usually 24 weeks is sufficient, depending on the structures involved, the adequacy of debridement, the type of soft-tissue wound cover, and wound vascularity (A-II); and for osteomyelitis, generally at least 46 weeks is required, but a shorter duration is sufficient if the entire infected bone is removed, and probably a longer duration is needed if infected bone remains (B-II). 13. If an infection in a clinically stable patient fails to respond to 1 antibiotic courses, consider discontinuing all antimicrobials and, after a few days, obtaining optimal culture specimens (C-III). 14. Seek surgical consultation and, when needed, intervention for infections accompanied by a deep abscess, extensive bone or joint involvement, crepitus, substantial necrosis or gangrene, or necrotizing fasciitis (A-II). Evaluating the limb's arterial supply and revascularizing when indicated are particularly important. Surgeons with experience and interest in the field should be recruited by the foot-care team, if possible. 15. Providing optimal wound care, in addition to appropriate antibiotic treatment of the infection, is crucial for healing (A-I). This includes proper wound cleansing, debridement of any callus and necrotic tissue, and, especially, off-loading of pressure. There is insufficient evidence to recommend use of a specific wound dressing or any type of wound healing agents or products for infected foot wounds. 16. Patients with infected wounds require early and careful follow-up observation to ensure that the selected medical and surgical treatment regimens have been appropriate and effective (B-III). 17. Studies have not adequately defined the role of most adjunctive therapies for diabetic foot infections, but systematic reviews suggest that granulocyte colony-stimulating factors and systemic hyperbaric oxygen therapy may help prevent amputations (B-I). These treatments may be useful for severe infections or for those that have not adequately responded to therapy, despite correcting for all amenable local and systemic adverse factors. 18. Spread of infection to bone (osteitis or osteomyelitis) may be difficult to distinguish from noninfectious osteoarthropathy. Clinical examination and imaging tests may suffice, but bone biopsy is valuable for establishing the diagnosis of osteomyelitis, for defining the pathogenic organism(s), and for determining the antibiotic susceptibilities of such organisms (B-II). 19. Although this field has matured, further research is much needed. The committee especially recommends that adequately powered prospective studies be undertaken to elucidate and validate systems for classifying infection, diagnosing osteomyelitis, defining optimal antibiotic regimens in various situations, and clarifying the role of surgery in treating osteomyelitis (A-III).

An open-label, randomized study comparing efficacy and safety of intravenous piperacillin/tazobactam and ampicillin/sulbactam for infected diabetic foot ulcers

BACKGROUND

Soft tissue and bone infections of the lower limb continue to be a frequent and serious complication in patients with diabetes mellitus. The best choice of antimicrobial for the empiric treatment of moderate to severe diabetic foot infections has not been established clearly.

METHODS

We conducted a prospective, randomized, open-label, multicenter trial comparing piperacillin/tazobactam (P/T) (4 g/0.5 g q8h) and ampicillin/sulbactam (A/S) (2 g/1 g q6h) as a parenteral treatment for 314 adult patients with moderate-to-severe infected diabetic foot ulcers. Patients with polymicrobial infections involving methicillin-resistant Staphylococcus aureus also received vancomycin 1 g q12h.

RESULTS

Clinical efficacy rates (cure or improvement) were statistically equivalent overall (81% for P/T vs. 83.1% for A/S), and median duration of treatment was similar in the clinically evaluable populations (nine days for P/T, 10 days for A/S). Drug-related adverse events for both study drugs were comparable in frequency and type.

CONCLUSIONS

Although both study drugs provide safe and effective empiric treatment for moderate-to-severe infected diabetic foot ulcers, piperacillin/tazobactam has the advantage of covering Pseudomonas aeruginosa (bacteriologic success rate of 85.7%), the most commonly isolated gram-negative pathogen in this study.

Antibiotic treatment of infected diabetic foot ulcers

Antimicrobial treatment can be effective in diabetic foot ulcers. However, choosing the appropriate regimen depends on the clinical and microbial presentation. This review describes the factors practitioners need to consider.

A systematic approach to diabetic foot infections

Foot infection is the most common reason for hospitalization and subsequent lower extremity amputation among persons with diabetes. Foot ulceration caused by diabetic neuropathy, trauma, and peripheral vascular disease can lead to a limbor life-threatening infection. The optimum treatment of these potentially devastating conditions depends on a multidisciplinary approach that addresses the related or underlying disorders and thus ensures proper wound healing and a positive outcome. In addition to antibiotic therapy, severe soft-tissue or bone infections may necessitate surgical treatment, including drainage, débridement, and vascular reconstruction. Initial (empiric) antibiotic therapy should provide coverage against staphylococci and streptococci and should be revised according culture results. Antibiotic therapy is not indicated in clinically noninfected wounds. The duration of antibiotic treatment can range from 1 week for mild infections to 6 weeks or more for residual osteomyelitis and severe deep tissue infections. Aggressive (and sometimes repeated or staged) surgical intervention and appropriate antibiotic therapy can reduce the likelihood of a major amputation and the duration of hospitalization.

Diagnosis and treatment of diabetic foot infections

Diabetic foot infections frequently cause morbidity, hospitalization, and amputations. Gram-positive cocci, especially staphylococci and also streptococci, are the predominant pathogens. Chronic or previously treated wounds often yield several microbes on culture, including gram-negative bacilli and anaerobes. Optimal culture specimens are wound tissue taken after debridement. Infection of a wound is defined clinically by the presence of purulent discharge or inflammation; systemic signs and symptoms are often lacking. Only infected wounds require antibiotic therapy, and the agents, route, and duration are predicated on the severity of infection. Mild to moderate infections can usually be treated in the outpatient setting with oral agents; severe infections require hospitalization and parenteral therapy. Empirical therapy must cover gram-positive cocci and should be broad spectrum for severe infections. Definitive therapy depends on culture results and the clinical response. Bone infection is particularly difficult to treat and often requires surgery. Several adjuvant agents may be beneficial in some cases.

Clinical efficacy, tolerability, and cost savings associated with the use of open-label metronidazole plus ceftriaxone once daily compared with ticarcillin/clavulanate every 6 hours as empiric treatment for diabetic lower-extremity infections in older males

BACKGROUND

Patients with diabetes mellitus, particularly those with poor glucose control, commonly experience various medical complications related to the disease (eg, renal impairment, decreased peripheral vascular circulation, suppressed immune function). Infections of the lower extremities can range from superficial cellulitis to ulcerative, deep soft-tissue infections to osteomyelitis that necessitates some degree of amputation.

OBJECTIVE

This study compared the efficacy, tolerability, and cost differences associated with the use of metronidazole plus ceftriaxone (MTZ/CTX) given once daily with those of ticarcillin/clavulanate potassium (T/C) given every 6 hours in hospitalized older males with diabetic lower-extremity infections.

METHODS

This prospective, open-label study was conducted at a Veterans Affairs Medical Center. Male patients with diabetes and a lower-extremity infection were randomized to receive MTZ/CTX 1 g once daily or T/C 3.1 g every 6 hours. Treatment success was determined at 96 hours or on discontinuation of antibiotic. Success was measured in terms of body temperature <38.3 degrees C (100.6 degrees F), normalization of the finger-stick blood sugar concentration, improvement in wound staging, or a white blood cell count <10,000 cells/mm3. Medication acquisition costs per treatment arm were calculated and compared.

RESULTS

Seventy patients were enrolled in the study (36 MTZ/CTX, 34 T/C). The study population had a mean (SD) age of 63.8 (10.8) years, a duration of diabetes of 12.4 (9.1) years, 0.5 (0.7) diabetes-related comorbidities, and an initial creatinine clearance of 67.1 (26.0) mL/min. There were no significant differences between groups at randomization. At 96 hours, treatment success was achieved in 31 (86%) patients in the MTZ/CTX group, compared with 28 (82%) patients in the T/C group (P=NS). Twenty-six patients were considered successfully treated on the final day of therapy in both the MTZ/CTX group (72%) and the T/C group (76%) (P=NS). There were no significant differences in primary or secondary measures of success between the 2 groups. No single or multiple baseline factors predicted treatment success or failure. No patient experienced adverse events considered related to study medication. MTZ/CTX was associated with savings of $61.06 per hospital admission, or $2198.05 for all patients who received this combination.

CONCLUSION

In this population of older males, once-daily MTZ/CTX was as well tolerated and effective as T/C in the treatment of diabetic lower-extremity infections and was associated with reduced institutional costs.

The role of beta-lactam/beta-lactamase inhibitor combinations in surgical infections

Many surgical infections are characterized by synergistic polymicrobial mixed infection, for which broad-spectrum antimicrobial therapy is usually administered on an empiric basis. Until relatively recently, standard empiric therapeutic regimens have involved the use of two or more antibiotics, such as aminoglycosides and anti-anaerobic agents, to achieve adequate aerobic and anaerobic coverage. There are often substantial drawbacks, however, such as drug-induced toxicity and high costs of treatment. Evidence from a number of clinical studies suggests that single-agent therapy with beta-lactam/beta-lactamase inhibitor combinations is a suitable and cost-effective alternative to multidrug regimens, as well as to monotherapy with cephalosporins or carbapenems in the treatment of intra-abdominal, gynecologic, and diabetic foot infections, and brain abscesses. These agents are also suitable for use in perioperative prophylaxis and may offer benefits over other agents in terms of reduced incidence of surgical wound infections and lower costs.

Diabetic foot infections and antibiotic therapy

Diabetic foot infections are associated with high morbidity and mortality rates as well as significant financial impact on the health care system. Improved patient outcomes and intelligent use of resources should determine the selection of diagnostic procedures and the therapeutic modalities used. Diabetic patients who develop lower extremity infections require a multidisciplinary approach in the management of their infections and other disorders. Aggressive surgical debridement and appropriate and adequate antibiotic therapy are necessary to successfully treat severe foot infections and permit faster recovery.

Experience with ampicillin/sulbactam in severe infections

The emergence of beta-lactamase-mediated resistance to established beta-lactam antibiotics prompted the development of beta-lactamase inhibitors for co-administration. Ampicillin has been combined with sulbactam for both parenteral and oral (as the mutual pro-drug sultamicillin) administration. The combination is active in vitro against a wide variety of Gram-positive and Gram-negative pathogens, including aerobic and anaerobic organisms. In clinical trials, ampicillin/sulbactam has proved clinically and bacteriologically effective against a variety of frequently encountered pediatric infections, including mild-to-moderate upper respiratory tract infections (acute otitis media, sinusitis, pharyngitis, and tonsillitis), severe post-operative and intra-abdominal infections, periorbital infections (which, left untreated, can lead to blindness, brain abscess, or death), acute epiglottitis, bacterial meningitis, and brain abscess. Ampicillin/sulbactam has also proved effective in the prevention of post-operative surgical infections in pediatric patients. The clinical efficacy profile of ampicillin/sulbactam and sultamicillin, combined with their excellent tolerability profile, make these agents attractive options for the management of many life-threatening infections in pediatric patients.

Pharmacotherapy of lower limb diabetic ulcers

OBJECTIVE

To discuss the pathophysiology, microbiology, and pharmacotherapy of lower extremity (LE) diabetic ulcers.

DATA SOURCES

A MEDLINE search from 1966 to April 1999 was conducted. The search was limited to humans and English-language journals. Key search words included "diabetic ulcer," "fluoroquinolones," "beta-lactam," "hyperbaric oxygen," "diabetes mellitus," "diabetic foot," and "growth factor."

STUDY SELECTION

Randomized and nonrandomized studies were selected for review. Results of randomized, placebo-controlled studies were emphasized more than nonrandomized results.

DATA SYNTHESIS

LE ulcers are a common cause of hospitalization, and cause significant morbidity and mortality. Staphylococcus aureus is the most common pathogen in non-limb-threatening infections; Gram-negative bacteria and anaerobes are most prevalent in limb-threatening and life-threatening infections. Oral antibiotic therapy may be used in non-limb-threatening infections, if adequate response is achieved in 24-48 hours; otherwise, intravenous antibiotics should be started. Intravenous antibiotics should be the initial therapy for limb-threatening or life- threatening ulcers. Antimicrobial therapy of at least 10-14 days has been effective in treating LE ulcers in the absence of osteomyelitis. Growth factors offer another treatment alternative, although only becaplermin is currently approved for diabetic ulcers.

CONCLUSION

Antibiotic therapy has been effective for the treatment of LE diabetic ulcers. However, further studies are required to identify optimal antibiotics and dosage regimens. Growth factors may have a role but additional research is needed to determine when best to initiate this therapy.

Evidence-based antibiotic therapy of diabetic foot infections

In addition to proper cleansing, debridement and local wound care, foot infections in diabetic patients require carefully selected antibiotic therapy. Serious infections necessitate hospitalization for initial parenteral broad-spectrum antibiotic therapy. Appropriately selected patients with mild infections can be treated as outpatients with oral (or even topical) therapy. Initial antibiotic selection is usually empirical, but definitive therapy may be modified based on culture results and the clinical response. Therapy should nearly always be active against staphylococci and streptococci, with broader-spectrum agents indicated if Gram-negative or anaerobic organisms are likely. In infected foot tissues levels of most antibiotics, except fluoroquinolones, are often subtherapeutic. The duration of therapy ranges from a week (for mild soft tissue infections) to over 6 weeks (for osteomyelitis). Recent antibiotic trials have shown that several intravenously or orally administered agents are effective in treating these infections, with no one agent or combination emerging as optimal. Suggested regimens based on the severity of infection are provided.

The role of beta-lactam/beta-lactamase inhibitors in the management of mixed infections

Microbiological studies show that the in vitro antimicrobial activity of sulbactam-ampicillin encompasses not only gram-positive and gram-negative aerobes, but also anaerobes. Such a broad spectrum of activity suggests its suitability as monotherapy for the empiric management of polymicrobial infections. Typical mixed infections, which are frequently life-threatening, include those occurring in the abdomen or pelvis, diabetic foot infections, and brain abscess. Numerous comparative clinical studies have revealed the clinical and bacteriological efficacy of sulbactam-ampicillin to be comparable to that of imipenem cilastatin and the second-generation cephalosporins cefoxitin and cefotetan. In addition, other studies have demonstrated that sulbactam-ampicillin monotherapy is cost-beneficial. A reduction in the duration of hospitalization, the lack of potentially toxic side-effects, and lower drug costs associated with monotherapy all contribute to the cost-effectiveness of sulbactam-ampicillin.