Home-based treatment of cellulitis with twice-daily cefazolin

OBJECTIVE

To assess the clinical outcome and pharmacokinetics of therapy with cefazolin for patients with cellulitis in a hospital-in-the-home (HIH) program.

DESIGN

Observational study with outcome data compared with previously published reports of therapy for cellulitis.

SETTING

A university teaching hospital and HIH unit, July 1996-December 1997.

PARTICIPANTS

Patients with cellulitis were eligible for inclusion provided their medical condition was stable, they did not require surgical intervention, and their social circumstances allowed home-based therapy.

INTERVENTION

Cefazolin 2 g intravenously twice daily, with regular nursing and medical assessment.

MAIN OUTCOME MEASURES

Clinical efficacy; peak and trough serum concentrations of cefazolin.

RESULTS

Fifty-seven patients (37 were men) with a mean age of 48 years (range, 18-90 years) had 61 episodes of moderate to severe cellulitis (41, lower limb; 17, upper limb; and three, face). They received a median of 11 doses of cefazolin (range, 3-27 doses). Clinical outcomes were: cure in 54, improvement in one, treatment failure in three, and in the remaining three episodes the outcome was indeterminate. Cefazolin concentrations were measured in 27 patients. All peak concentrations were more than 40 micrograms/mL, while trough concentrations were all above the MIC90 of the expected pathogens: median, 3.2 micrograms/mL (range: 0.4-18.5 micrograms/mL). Cefazolin was well tolerated.

CONCLUSIONS

Twice-daily cefazolin 2 g intravenously is a convenient and effective option for home-based treatment of patients with cellulitis. Its clinical efficacy is comparable with other treatment regimens.

Antimicrobial resistance testing of Helicobacter pylori: a comparison of Etest and disk diffusion methods

Routine antimicrobial resistance testing of Helicobacter pylori is more commonly performed since the correlation between metronidazole resistance and failure to eradicate using this drug, has been made. While resistance testing of H. pylori by Etest is simple to perform, it is expensive compared to disk diffusion methods. In this study the Etest was compared with a modified Kirby-Bauer disk diffusion (NCCLS) method for routine resistance screening of H. pylori. Fifty one pre-treatment isolates were tested against amoxycillin, metronidazole, tetracycline and erythromycin by both Etest and disk diffusion using NCCLS guideline strength disks. Clarithromycin was tested by Etest only. Nitroimidazole and macrolide resistance were detected using the modified Kirby-Bauer disk diffusion method which correlated with Etest minimum inhibitory concentration (MIC). Resistance rates were 49% for metronidazole and 8% for clarithromycin. Cross resistance occurs with macrolides against H. pylori and allows testing of erythromycin to predict resistance to clarithromycin. The very low MICs obtained with H. pylori against amoxycillin and tetracycline require the use of Etest or lower strength disk methods to be used.

Neurological complications of chlamydial infections: case report and review

We describe a patient with Chlamydia pneumoniae infection who presented with cerebellar dysfunction, followed by respiratory failure requiring mechanical ventilation. C. pneumoniae is an important respiratory pathogen, and other clinical manifestations, including neurological syndromes, are being increasingly recognized. Meningoencephalitis and other neurological complications have also been described in patients with infections due to Chlamydia psittaci and Chlamydia trachomatis. Chlamydial infections should be included in the differential diagnosis of neurological syndromes, including cerebellar dysfunction.

Risk factors for adverse cutaneous reactions associated with intravenous vancomycin

We retrospectively studied adverse cutaneous reactions associated with intravenous vancomycin therapy over a 14-month period when two different brands of vancomycin were used. Of 224 adults, 12 (5.4%) had infusion-related reactions; ten of 174 patients who received more than one day of vancomycin (5.7%) had delayed cutaneous reactions. Age less than 40 years was a risk factor for both infusion-related and delayed reactions by both univariate and multivariate analysis. Duration of therapy greater than 7 days was a risk factor for delayed reactions. There was a significant increase in adverse cutaneous reactions associated with the use of a particular batch of vancomycin, although analytical testing of this batch failed to identify any difference from other batches associated with routine rates of adverse reactions. Awareness of vancomycin-associated infusion-related and delayed cutaneous reactions is necessary, and the risk factors associated with these reactions may have important clinical implications.

Cost-effectiveness of ampicillin/sulbactam versus imipenem/cilastatin in the treatment of limb-threatening foot infections in diabetic patients

A cost-effectiveness analysis was performed following a double-blind, randomized study of ampicillin/sulbactam (A/S) versus imipenem/cilastatin (I/C) for the treatment of limb-threatening foot infections in 90 diabetic patients. There were no significant differences between the treatments in terms of clinical success rate, adverse-event frequency, duration of study antibiotic treatment, or length of hospitalization. Costs of the study antibiotics, treatment of failures and adverse events, and hospitalization were calculated. Mean per-patient treatment cost in the A/S group was $14,084, compared with $17,008 in the I/C group (P = .05), primarily because of lower drug and hospitalization costs and less-severe adverse events in the A/S group. Sensitivity analyses varying drug prices or hospital costs demonstrated that A/S was consistently more cost-effective than I/C. Varying the clinical success rate for each drug revealed that I/C would have to be 30% more effective than A/S to change the economic decisions.

A meta-analysis of studies on the safety and efficacy of aminoglycosides given either once daily or as divided doses

We performed a meta-analysis of randomised clinical studies in which the efficacy and toxicity of the same total daily dose of aminoglycosides administered once-daily was compared with multiple divided daily dosing for treating human infections. Of twenty-eight publications identified from a literature search using Medline 19 publications of 20 study comparisons involving 2881 patients met the criteria for analysis. Netilmicin was investigated in 11 studies, amikacin in seven studies and gentamicin in two studies but no studies of tobramycin met the inclusion criteria. The meta-analysis showed that there was a small, statistically significant difference in clinical efficacy of 3.5% (95% confidence intervals 0.5% to 6.5%, P = 0.027) in favour of once-daily administration but no significant differences in bacteriological efficacy or nephrotoxicity were detected. Auditory and vestibular toxicity rates were low for all agents and no differences in these toxicities were identified between once-daily or multiple-dose administration regimens either clinically or by audiometry or electronystagmography. Aminoglycosides can be given once-daily without loss of efficacy or increased toxicity offering greater simplicity and potentially improved cost-effectiveness than can be achieved by giving these drugs in divided doses.

Treatment of urinary tract infections

Urinary tract infections (UTIs) are common conditions in clinical practice. For uncomplicated UTIs, the causative organisms and their antimicrobial susceptibility profiles are generally predictable, and empiric short course (3 day) antibiotic therapy after an abbreviated laboratory workup is advocated. Acute pyelonephritis requires a 2 week antibiotic course, often with initial parenteral therapy. Women with frequent recurrences of UTIs may require intermittent self-treatment or continuous or postcoital antibiotic prophylaxis. Catheter-associated UTIs generally only require treatment if the patient shows signs of systemic infection. Treatment of asymptomatic bacteriuria is only recommended in certain circumstances. Careful consideration of the clinical circumstances, the patient's known or predicted urinary tract anatomy, and the antibiotic susceptibility of the bacterial pathogen(s) are critical factors in the choice of appropriate therapy for urinary tract infections.

In vitro inhibition of Helicobacter pylori NCTC 11637 by organic acids and lactic acid bacteria

In this study the effects of both pH and organic acids on Helicobacter pylori NCTC 11637 were tested. Lactobacillus acidophilus, Lact. casei, Lact. bulgaricus, Pediococcus pentosaceus and Bifidobacterium bifidus were assayed for their lactic acid production, pH and inhibition of H. pylori growth. A standard antimicrobial plate well diffusion assay was employed to examine inhibitory effects. Lactic, acetic and hydrochloric acids demonstrated inhibition of H. pylori growth in a concentration-dependent manner with the lactic acid demonstrating the greatest inhibition. This inhibition was due both to the pH of the solution and its concentration. Six strains of Lact. acidophilus and one strain of Lact. casei subsp. rhamnosus inhibited H. pylori growth where as Bifidobacterium bifidus, Ped. pentosaceus and Lact. bulgaricus did not. Concentrations of lactic acid produced by these strains ranged from 50 to 156 mmol l-1 and correlated with H. pylori inhibition. The role of probiotic organisms and their metabolic by-products in the eradication of H. pylori in vivo remains to be determined.

Home intravenous antibiotic therapy. A safe and effective alternative to inpatient care

OBJECTIVE

To assess the practicality, safety, cost effectiveness and outcome of receiving intravenous antibiotics at home.

METHODS

Patients with serious bacterial infections requiring parenteral antibiotic therapy were enrolled in a pilot program to receive treatment at home. Antibiotics were premixed in the hospital pharmacy and administered by the Royal District Nursing Service, and medical back-up was provided.

RESULTS

Twenty patients (mean age, 58 years; range, 19-84 years) received 21 courses of intravenous antibiotics at home (mean duration +/- SD, 26 +/- 9 days; range, 11-44 days). Conditions treated included osteomyelitis (10 patients), endocarditis (5), vascular graft and pacemaker sepsis (4), and chronic cellulitis (1). Treatment at home was well tolerated with no significant complications, and cure was achieved in 18 of the 20 patients. It was both efficient and cost effective, with a mean benefit in treatment costs between home and the equivalent inpatient therapy of at least $112 per day for the 538 days that home therapy was provided. Moreover, the reduced bed use could allow an additional hospital throughput of between 86 and 107 patients annually.

CONCLUSIONS

Home intravenous antibiotic therapy is safe, effective and well tolerated. It allows more efficient inpatient care and reduces total treatment costs in an important subpopulation of patients.

Diabetic foot infections. Antimicrobial therapy

Pedal infection in diabetic patients is both a common and potentially disastrous complication that can progress rapidly to irreversible septic gangrene necessitating amputation of the foot. The choice of optimal antibiotic therapy depends on an accurate assessment of sepsis severity, reliable microbiologic data, and consideration of host factors, such as renal and vascular impairment. Empiric broad-spectrum antibiotic regimens are generally preferred because of the polymicrobial nature of most pedal infections. Mild infections may be treated as an outpatient with oral antibiotics and close clinical review while moderate/severe (limb-threatening) and severe (life-threatening) infections require resection of necrotic tissue, parenteral broad-spectrum antibiotic therapy, and in some cases, lower limb revascularization once sepsis has been controlled. Pedal osteomyelitis frequently requires prolonged antibiotic therapy or resection of involved bone. In this article, treatment trials are reviewed and suitable antibiotic regimens commensurate with the severity of infection are proposed.

Random amplified polymorphic DNA and plasmid analyses used in investigation of an outbreak of multiresistant Klebsiella pneumoniae

Multiresistant Klebsiella pneumoniae strains with plasmid-borne extended-spectrum beta-lactamases (ESBL) are increasingly frequent nosocomial pathogens. A major outbreak of clinical infections, mainly involving patients in the Newborn Services Unit with limited spread to adult patients, occurred at our hospital. This epidemic was investigated by typing the isolates phenotypically and with random amplified polymorphic DNA analysis (RAPD) and plasmid analysis. Forty-eight isolates, consisting of 44 consecutive clinical isolates and 4 selected surveillance isolates, were studied. A single decamer primer was used for the RAPD, and this was effective in demonstrating that the majority of isolates (45 of 48) had the same profile. Three other isolates had different RAPD patterns identifying them as nonepidemic strains. Plasmids were extracted by alkaline lysis with Magic-miniprep kits from 10 isolates selected to represent the epidemic and nonepidemic strains. This method produced small (< 20-kb) plasmids; larger ESBL-carrying plasmids were not produced, but the small plasmids nonetheless allowed strain differentiation. Antibiotic susceptibility patterns alone were not reliable as strain indicators, since some isolates with the RAPD pattern characteristic of the epidemic strains did not express ESBL and therefore were susceptible to extended-spectrum cephalosporins. The investigation showed the predominance of a single epidemic strain that was transmitted between patients in the Newborn Services Unit. RAPD was the best of the methods used for detecting strain differences, and its speed and ability to type a wide variety of species suggest that it will be an increasingly useful molecular epidemiologic tool.

Probing to bone in infected pedal ulcers. A clinical sign of underlying osteomyelitis in diabetic patients

OBJECTIVE

To assess a bedside technique for diagnosing osteomyelitis.

DESIGN

We prospectively assessed infected pedal ulcers for detectable bone by probing with a sterile, blunt, stainless steel probe. We then examined the relationship between detection of bone and the presence or absence of osteomyelitis that was defined histopathologically and/or clinically.

SETTING

A tertiary care center.

PATIENTS

Seventy-five hospitalized diabetic patients with a total of 76 infected foot ulcers were studied.

RESULTS

Osteomyelitis was diagnosed in 50 instances (66%) and was excluded in 26 instances. Bone was detected by probing in 33 of 50 ulcers with contiguous osteomyelitis; in contrast, bone was probed in only four of 26 ulcers without contiguous osteomyelitis (P < .001). Bone detected on probing was visible in only three instances. Palpating bone on probing the pedal ulcer had a sensitivity of 66% for osteomyelitis, a specificity of 85%, a positive predictive value of 89%, and a negative predictive value of 56%.

CONCLUSIONS

Palpation of bone in the depths of infected pedal ulcers in patients with diabetes is strongly correlated with the presence of underlying osteomyelitis. If bone is palpated on probing, specialized roentgenographic and radionuclide tests to diagnose osteomyelitis are unnecessary. Probing for bone should be included in the initial assessment of all diabetic patients with infected pedal ulcers.

Cerebral sparganosis in an East Timorese refugee

OBJECTIVE

To report the first case of cerebral sparganosis diagnosed in Australia.

CLINICAL FEATURES

A 23-year-old East Timorese refugee, whose diet before migration included raw snakes and frogs, presented with a generalised tonic-clonic seizure and a nine-month history of episodic left hemianaesthesia. Computerised axial tomography of the brain showed a right frontal lesion, which was excised, and histological examination demonstrated changes typical of sparganosis.

INTERVENTION AND OUTCOME

Excision of the lesion resulted in cure. Postoperative eosinophilia and a subcutaneous nodule presumed to be due to disseminated sparganosis resolved following a course of praziquantel.

CONCLUSION

Clinicians should consider the possibility of unusual parasitic infections in refugees who present with intracranial space-occupying lesions, especially those from developing countries. A dietary history may aid the diagnosis.

Use of ampicillin/sulbactam versus imipenem/cilastatin in the treatment of limb-threatening foot infections in diabetic patients

In a double-blind randomized trial, imipenem/cilastatin (I/C; 500 mg every 6 hours) and ampicillin/sulbactam (A/S; 3 g every 6 hours) were compared in regard to their efficacy for initial empirical and definitive parenteral treatment of limb-threatening pedal infection in diabetic patients. The major endpoints of treatment were cure (resolution of soft-tissue infection), failure (inadequate improvement, necessitating a change in antibiotic therapy), and eradication (clearance of all pathogens from the wound and any bone cultures). Patients in the two treatment groups were similar in regard to the severity of diabetes; presence of neuropathy and peripheral vascular disease; site and severity of infection; pathogen isolated; and frequency of osteomyelitis (associated with 68% of the 48 A/S-treated infections and 56% of the 48 I/C-treated infections). After 5 days of empirical treatment, improvement was noted in 94% of the A/S and 98% of the I/C recipients. At the end of definitive treatment (days' duration [mean +/- SD]: 13 +/- 6.5 [A/S], 14.8 +/- 8.6 [I/C]), outcomes were similar: cure, 81% (A/S) vs. 85% (I/C); failure, 17% (A/S) vs. 13% (I/C); and eradication, 67% (A/S) vs. 75% (I/C). Treatment failures were associated with the presence of antibiotic-resistant pathogens and possible nosocomial acquisition of infections. The number of adverse events among patients in the two treatment groups was similar: 7 in the A/S group (4 had diarrhea and 3 had rash) and 9 in the I/C group (5 had diarrhea, 2 had severe nausea, 1 had rash, and 1 had seizure). Efficacy of A/S and I/C is similar for initial empirical and definitive treatment of limb-threatening pedal infection in patients with diabetes.