BMY-28100, a new oral cephalosporin: antimicrobial activity against nearly 7,000 recent clinical isolates, comparative potency with other oral agents, and activity against beta-lactamase producing isolates

Staphylococcal skin infections in children: rational drug therapy recommendations

Staphylococcus aureus remains one of the most common and troublesome of bacteria causing disease in humans, despite the development of effective antibacterials and improvement in hygiene. The organism is responsible for over 70% of all skin and soft tissue infections in children and accounts for up to one-fifth of all visits to pediatric clinics. Skin and soft tissue infections that are predominantly caused by S. aureus include bullous and non-bullous impetigo, folliculitis, furunculosis, carbunculosis, cellulitis, surgical and traumatic wound infections, mastitis, and neonatal omphalitis. Other skin and soft tissue infections may also be caused by S. aureus but are often polymicrobial in origin and require special consideration. These include burns, decubitus ulcers (particularly in the perianal region), puncture wounds of the foot, as well as human and mammalian bites. Treatment of staphylococcal skin infections varies from topical antiseptics to prolonged intravenous antibacterials, depending on severity of the lesions and the health of the child. The treatment of choice for oral antibacterials remains the penicillinase-resistant penicillins such as flucloxacillin. Cefalexin and erythromycin are suitable cost-effective alternatives with broader cover, although care must be taken with the use of macrolides because of development of resistance to multiple families of antibacterials, particularly the lincosamides. Other cephalosporins such as cefadroxil and cefprozil are also effective, can be given once daily and have a better tolerability profile -- while azithromycin has a further advantage of a 3-day course. However, all of these agents are more expensive. Although the antibacterials have been given for 10 days in most clinical trials, there is no evidence that this duration is more effective than a 7-day course. In children requiring intravenous therapy, ceftriaxone has a major advantage over other antibacterials such as sulbactam/ampicillin and cefuroxime in that it can be given once daily and may, therefore, be suitable for outpatient treatment of moderate-to-severe skin infections. Newer-generation cephalosporins and loracarbef are also effective and have a broader spectrum of activity, but do not offer any added benefit and are significantly more expensive. Skin and soft tissue infections due to methicillin-resistant S. aureus (MRSA) are still relatively uncommon in children. Well children with community-acquired MRSA infections can be treated with clindamycin or trimethoprim-sulfamethoxazole (cotrimoxazole), but must be observed closely for potentially severe adverse effects. In severe infections, vancomycin remains the treatment of choice, while intravenous teicoplanin and clindamycin are suitable alternatives. Linezolid and quinupristin/dalfopristin are currently showing great promise for the treatment of multi-resistant Gram-positive infections. While the choice of antibacterial is important, supportive management, including removal of any infected foreign bodies, surgical drainage of walled-off lesions, and regular wound cleaning, play a vital role in ensuring cure.

Efficacy of penicillin versus cefdinir in eradication of group A streptococci and tonsillar flora

Core tonsillar cultures were obtained from 40 children with recurrent tonsillitis treated with either penicillin or cefdinir. Group A beta-hemolytic streptococci were isolated from 11 penicillin- and 3 cefdinir-treated (P < 0.001) patients. beta-Lactamase producers were recovered from 17 penicillin- and 3 cefdinir-treated (P < 0.01) patients. Inhibiting alpha-hemolytic streptococci were isolated less often from penicillin-treated patients than from cefdinir-treated patients.

Antibiotics in the management of pediatric skin disease

An increasingly large number of antibiotics are available for the treatment of uncomplicated skin and skin structure infections in children. Primary factors in the choice among these agents are the antibiotic resistance profile of the target pathogen(s), and the antibiotic's spectrum of activity, pharmacologic properties, potential adverse reactions and interactions and propensity to select for the emergence of resistant organisms. Based on a consideration of these principles, this article provides a practical guide to the use of antibiotics in the management of common cutaneous infections in the pediatric population.

Impetigo: an overview

This article reviews in detail the pathogenesis, clinical characteristics and management of impetigo in children. Impetigo is the most common bacterial skin infection of children. Most cases of nonbullous impetigo and all cases of bullous impetigo are caused by Staphylococcus aureus. The remainder of cases of nonbullous impetigo are due to group A beta hemolytic streptococci (GABHS). GABHS colonize the skin directly by binding to sites on fibronectin that are exposed by trauma. In contrast, S. aureus colonizes the nasal epithelium first; from this reservoir, colonization of the skin occurs. Patients with recurrent impetigo should be evaluated for carriage of S. aureus. Superficial, localized impetigo may be treated successfully in more than 90% of cases with topical application of mupirocin ointment. Impetigo that is widespread or involves deeper tissues should be treated with a beta-lactamase-resistant oral antibiotic. The choice of antibiotics is affected by the local prevalence of resistance to erythromycin among strains of S. aureus, antibiotic cost and availability, and issues of compliance.

A review of the microbiology of amoxycillin/clavulanic acid over the 15 year period 1978-1993

A review of the published literature over the period 1978-1993 was undertaken to assess any changes in the prevalence of beta-lactamase-producing bacterial pathogens and also any changes in the susceptibility in these pathogens to amoxycillin/clavulanate. The review has involved the examination of over 1500 publications. The review shows that in general there has been an increase in the frequency of beta-lactamase-producing pathogens resistant to ampicillin and amoxycillin but there is no evidence for any significant increase in resistance to amoxycillin/clavulanate over the period of the review.

Comparative microbiological activity and pharmacokinetics of cefprozil

In vitro studies on the activity of cefprozil have been conducted in Europe and North America. Against gram-negative bacilli, cefprozil and cefaclor are at least two to four times more active than cephalexin. Cefixime is more active against these organisms. Against gram-positive cocci, cefprozil is at least two to four times more active than cefaclor and cephalexin; cefixime has limited gram-positive activity, and is particularly inactive against staphylococci (MIC90 32 mg/l). Cefprozil is highly active against Streptococcus pneumoniae (unlike cefixime). Those strains of this genus that display intermediate resistance to pneumococci are more susceptible to cefprozil than cefaclor. Neisseria species and Moraxella catarrhalis are susceptible to cefprozil (MIC90 0.06 and 1 mg/l). beta-lactamase-producing strains of Haemophilus influenzae appear to be susceptible to cefprozil, as the reported MIC90 is 2-4 mg/l. Enterococci, Pseudomonas aeruginosa, and those strains of the Enterobacteriaceae that commonly possess a chromosomal cephalosporinase (e.g., Providencia, Morganella and Enterobacter) are generally considered to be resistant to cefprozil as well as to other oral cephalosporins. Cefprozil appears to display enhanced stability to the commonly encountered Tem-1 and SHV-1 plasmid-mediated beta-lactamases, as found in Haemophilus influenzae, Neisseria gonorrhoeae and the Enterobacteriaceae. Cefprozil is rapidly absorbed, reaching a maximum concentration 0.9 to 1.2 h post-dose. Following oral doses of 250 and 500 mg, the Cmax is 6.2 and 10.0 mg/l respectively. Serum half-lives are generally reported as between 1.2 and 1.4 h, and urine recovery is high, 57-70%.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy and safety of cefprozil versus other beta-lactam antibiotics in the treatment of lower respiratory tract infections

Cefprozil was evaluated in four multicentre comparative studies in the treatment of acute respiratory tract infections. In two studies, cefprozil 500 mg q. 12 hours was compared to cefaclor 500 mg q. eight hours for ten days of therapy. Randomization was on a 2:1 (cefprozil:cefaclor) basis in the European centres and 1:1 in North America. The clinical efficacy in acute bronchitis was 88% (284 out of 324 patients) for cefprozil and 88% (183 out of 208) for cefaclor, with successful bacteriological eradication of the causative pathogen in 86% and 82% of the patients, respectively. Amongst the patients with acute exacerbations of chronic bronchitis, the clinical response rate of 80% (59 out of 74) for cefprozil appeared superior to that of cefaclor at 62% (p = 0.067), whilst the bacteriological response rates were 62% (36 out of 58) for cefprozil and 74% (20 out of 27) for cefaclor. In pneumonia, the clinical response rates for cefprozil and cefaclor therapy were similar, 82% vs. 79%, although bacteriological eradication rates were better for cefprozil at 82% than for cefaclor at 71%. In the comparison of cefprozil with cefuroxime axetil, a total of 170 patients were evaluable. The clinical and bacteriological response rates for cefprozil of 95% and 100% were better than those for cefuroxime axetil 500 mg q. 12 hours of 84% and 75%, respectively. In the cefprozil vs. amoxicillin-clavulanate, 500 mg q. eight hours comparative study, the two antibiotics displayed no significant difference in clinical or bacteriological responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum sickness-like reactions associated with cefprozil therapy

Four patients had serum sickness-like reactions during treatment with cefprozil, a new cephalosporin. Two patients had had previous mild reactions associated with cephalosporin therapy. It remains uncertain whether cefprozil-associated serum sickness-like reaction represents a unique or a class-related adverse drug reaction.

Effects of blood medium supplements on activities of newer cephalosporins tested against enterococci

This comparative study determined the effect of blood on the antienterococcal activities of the newer cephalosporins. Standardized disk diffusion susceptibility tests were performed with 57 strains of enterococci (30 Enterococcus faecalis strains) on Mueller-Hinton agar with and without 5% sheep blood supplementation. Twelve cephalosporins representing five different structural groups (based on the 7-alpha position substitution) were tested. The greatest frequency of activity enhancement by blood was observed with cefdaloxime and cefdinir (7-alpha hydroxyimino group) against E. faecalis. Cephalosporins with a 7-alpha methoxyimino group (cefpodoxime, cefepime, and cefpirome) had marked increases in zone diameters (3 to > 9 mm) when tested with the blood supplement. Cephems with 7-alpha amino or carboxy substitutions did not demonstrate any enhanced activity. Awareness of this phenomenon is important for the interpretation and accuracy of cephalosporin susceptibility testing.

Susceptibility of United States clinical trial isolates to cefprozil and cefaclor

First bacterial isolates (n = 2022) from patients enrolled in the United States cefprozil clinical trials were tested for susceptibility to cefprozil and cefaclor. Cefprozil was two- to eightfold more active than cefaclor against Gram-positive bacteria based on minimum inhibitory concentration (MIC50 and MIC90) values. The differential was greatest, for the most part, for the 80% of isolates of each species with the lowest MICs. Against Gram-negative bacterial species, the two cephalosporins were very similar in activity and MIC90 values ranged from 2 to 8 micrograms/ml for the most prevalent pathogens except Enterobacter spp., which were resistant. The majority of streptococci (98%) were susceptible to < or = 0.5 microgram/ml of cefprozil, and the majority of staphylococci tested (> 90%) were susceptible to < or = 4 micrograms/ml of cefprozil. These results for isolates primarily from community-acquired infections were similar to previously reported results from uncharacterized or hospital-associated isolates.

Review of in vitro activity, pharmacokinetic characteristics, safety, and clinical efficacy of cefprozil, a new oral cephalosporin

OBJECTIVE

To review the pharmacokinetics, microbiology, clinical efficacy, safety, and tolerance of cefprozil, a new, broad-spectrum oral cephalosporin.

DATA SOURCES

Published clinical trials and microbiologic, pharmacokinetic, and safety data were identified by MEDLINE; additional references were derived from bibliographies of these articles; microbiologic data on file were provided by Bristol-Myers Squibb.

STUDY SELECTION

Only published comparative clinical trial reports are included in the review of clinical efficacy. Noncomparative clinical data pertaining to uses of cefprozil not approved by the Food and Drug Administration are not included.

DATA SYNTHESIS

Data are presented on the in vitro microbiologic activity of cefprozil against 10,152 bacterial isolates, including most of the clinically important streptococci (e.g., Streptococcus pyogenes, Streptococcus pneumoniae), beta-lactamase-positive and -negative Staphylococcus aureus and Haemophilus influenzae, Moraxella catarrhalis, Escherichia coli, Proteus mirabilis, Clostridium difficile, and numerous other gram-negative aerobes and anaerobes. In clinical trials, cefprozil appears to be at least as effective as commonly used comparison agents such as cefaclor, cefixime, and amoxicillin/clavulanic acid. Additionally, cefprozil is better tolerated than the latter two agents, especially with regard to gastrointestinal adverse effects.

CONCLUSIONS

Cefprozil is a broad-spectrum cephalosporin that provides coverage against both gram-negative and -positive bacteria that may cause otitis media, pharyngitis/tonsillitis, skin and skin-structure infections, secondary bacterial infection of acute bronchitis, and acute bacterial exacerbations of chronic bronchitis. The beta-lactamase stability of cefprozil appears to exceed that of other oral cephalosporins for some important pathogens. Cefprozil is used primarily for second-line treatment as less-expensive, first-line generic alternatives generally are available. Cefprozil demonstrates clinical advantages over many other orally administered beta-lactam antibiotics in terms of antimicrobial spectrum, a once- or twice-daily dosing regimen, and/or reduced incidence of adverse effects.

Evaluation of bacterial interference and beta-lactamase production in management of experimental infection with group A beta-hemolytic streptococci

The in vivo effects of penicillin and cefprozil therapy on the interaction between organisms commonly recovered from inflamed tonsils were studied by using a subcutaneous abscess model in mice. These organisms were group A beta-hemolytic streptococci (GABHS), Streptococcus salivarius (which is capable of interfering with GABHS), and Staphylococcus aureus. In mice infected with GABHS and S. salivarius alone or in combination, penicillin eliminated both organisms and cefprozil eliminated GABHS and S. aureus but not S. salivarius. Penicillin did not, however, reduce the number of GABHS or S. salivarius in the presence of S. aureus. The present study demonstrated the ability of beta-lactamase-producing S. aureus to protect GABHS from penicillin. However, no such protection was present following the administration of cefprozil. Furthermore, the preservation of S. salivarius that interferes with GABHS growth may provide protection from reinfection with GABHS. This study supports and provides an explanation for the increased efficacies of cephalosporins administered orally over that of penicillin when treating patients with acute GABHS pharyngitis or tonsillitis.

Cefprozil

Cefprozil is a new, orally bioavailable, cephalosporin with significant activity against the bacteria commonly associated with upper and lower respiratory tract infection, and skin and soft tissue infections. Its absorption and elimination dynamics suggest once- or twice-daily dosing. The low-rate of gastrointestinal and dermatologic side effects associated with cefprozil administration suggest that it may have a significant role in the management of patients with these infections. Children with pharyngitis or urinary tract infection are more appropriately treated with antibiotics having a narrower spectrum of activity. With a variety of newer cephalosporins being marketed in the early 1990s, it will be important for the clinician to examine the data from ongoing comparative clinical trials to determine which antibiotic is best for a patient with a specific infection and whether the added cost justifies its use.

Cefprozil. A review of its antibacterial activity, pharmacokinetic properties, and therapeutic potential

Cefprozil is an orally active cephalosporin which has demonstrated activity against a wide range of organisms in vitro. It is particularly active against the Gram-positive organisms Streptococcus pyogenes, pneumoniae and agalactiae and against methicillin-susceptible Staphylococcus aureus. Strains of methicillin-resistant S. aureus are not susceptible to cefprozil. Cefprozil is also moderately active against Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, many Enterobacteriaceae and certain anaerobic organisms, and is relatively stable to hydrolysis by a number of beta-lactamases. In comparative trials, the clinical and bacteriological efficacy of cefprozil 500mg or 20 mg/kg administered once or twice daily has been comparable with multiple daily dosage regimens of erythromycin in patients with tonsillitis or pharyngitis, with cefaclor and amoxicillin/clavulanate in lower respiratory tract infections, with amoxicillin/clavulanate and erythromycin in skin and skin-structure infections and with cefaclor in acute uncomplicated urinary tract infections. The clinical efficacy of cefprozil is similar to that of cefaclor in patients with tonsillitis or pharyngitis but the bacteriological efficacy of cefprozil is significantly greater than that of cefaclor. Cefprozil is clinically more effective than cefuroxime axetil in the treatment of lower respiratory tract infections and demonstrated greater efficacy than cefaclor in one of 2 comparative studies when administered twice daily in patients with skin and skin-structure infections. In children with acute otitis media, cefprozil 15 mg/kg twice daily was as effective as cefaclor or amoxicillin/clavulanate 13.3 mg/kg 3 times daily and was as effective as cefixime 8 mg/kg once daily. The most frequently reported adverse effects associated with cefprozil, diarrhoea and nausea, are usually mild to moderate in severity and discontinuation of treatment is rarely necessary. Thus, cefprozil with its convenient administration regimen appears to be a suitable alternative to cefaclor, cefixime, amoxicillin/clavulanate or erythromycin for the treatment of upper and lower respiratory tract infections, skin and skin-structure infections, and otitis media in children. While cefprozil has shown similar efficacy to cefaclor in the treatment of uncomplicated urinary tract infections, well-controlled clinical trials comparing its efficacy with that of cotrimoxazole (trimethoprim+sulfamethoxazole) in this indication are required.

Inability of cephalothin testing to predict cefprozil susceptibility

The 30-micrograms cefprozil disk and the cephalosporin class (30-micrograms cephalothin) disk were compared for their abilities to predict cefprozil susceptibility by agar disk diffusion testing. High error (5.02% major and 14.11% minor) rates were encountered with the cephalothin disk and were most frequently observed for Escherichia coli and Enterococcus faecalis. The cefprozil disks resulted in rates of 0.05% very major, 0% major, and 3.72% minor errors. Thus, the 30-micrograms cefprozil disk is more desirable for predicting cefprozil susceptibility.

Comparative efficacy and safety of cefprozil (BMY-28100) and cefaclor in the treatment of acute group A beta-hemolytic streptococcal pharyngitis

Cefprozil (BMY-28100) is a semisynthetic cephalosporin with broad-spectrum antibacterial activity and prolonged serum elimination half-life allowing for once-a-day oral administration. In vitro, cefprozil demonstrates excellent activity against Staphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae, and Moraxella catarrhalis. Cefprozil (500 mg once daily) was compared to cefaclor (250 mg three times daily) in an open, randomized, comparative trial for the treatment of acute group A beta-hemolytic streptococcal pharyngitis. Ninety-four patients were enrolled in this study; 53 patients were evaluable for clinical and bacteriological response assessment. Seventy-eight patients were evaluable for safety assessment. Three patients (all in the cefprozil treatment group) required disenrollment because of side effects, mainly nausea. Clinical and bacteriological responses were comparable for both study drugs. Leukopenia and nausea, the most common side effects observed, were more common in the cefprozil-treated group. Cefprozil appears to be an appropriate alternative to cefaclor for the treatment of acute group A beta-hemolytic streptococcal pharyngitis. However, because of the small number of patients eligible for efficacy assessment, a large type II (beta) error was expected in our study, which may have resulted in a potential failure to detect a difference between both treatment groups. A larger study would be required to determine the proper role of cefprozil in the treatment of group A beta-hemolytic streptococcal infections.

Antimicrobial resistance among respiratory isolates of Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae in the United States

A national surveillance study was conducted to determine trends in antimicrobial resistance patterns among three common causes of community-acquired respiratory tract infections. Fifteen participating U.S. medical centers submitted clinically significant isolates of Haemophilus influenzae, Moraxella (Branhamella) catarrhalis, and Streptococcus pneumoniae to two central laboratories for testing with a group of 12 antimicrobial agents. The majority of isolates were recovered from adult males greater than 50 years old. Overall, 84.1% of 378 M. catarrhalis and 16.5% of 564 H. influenzae (29.5% of type b strains; 15.0% of non-type b strains) produced beta-lactamase and were thus resistant to penicillin, ampicillin, and amoxicillin. Resistance in H. influenzae to other agents was 2.1% to tetracycline, 0.7% to trimethoprim-sulfamethoxazole, 1.1% to cefaclor, and 0.2% to cefuroxime and amoxicillin-clavulanate, while the M. catarrhalis isolates yielded very low MICs of these latter drugs. As demonstrated in prior studies, erythromycin showed little activity against H. influenzae. Of 487 S. pneumoniae isolates, 1 (0.2%) was penicillin resistant, while 3.8% were relatively resistant to penicillin, 4.5% were resistant to trimethoprim-sulfamethoxazole, 2.3% were resistant to tetracycline, 1.2% were resistant to chloramphenicol, and 0.2% were resistant to erythromycin. Overall, the lowest resistance rates for these common bacterial respiratory pathogens were noted with amoxicillin-clavulanate, cefuroxime, and cefaclor.

beta-Lactamase stability and in vitro activity of oral cephalosporins against strains possessing well-characterized mechanisms of resistance

The in vitro activity of four oral cephalosporins was assessed in dilution tests with 50 isolates of the family Enterobacteriaceae possessing well-characterized mechanisms of resistance to beta-lactam antibiotics. The interaction of the drugs with a broad array of beta-lactamases was also determined in spectrophotometric assays and tests for enzyme induction. Overall, the percentages of strains susceptible to each of the study drugs were 82% for cefixime, 62% for cefuroxime, 58% for cephalexin, and 44% for cefaclor. The poor activity of the older cephalosporins was due to a high degree of susceptibility to hydrolysis by both plasmid-mediated and chromosomally mediated beta-lactamases. For cefaclor, higher MICs were associated with higher levels of plasmid-mediated beta-lactamases in the strains. Resistance to cefuroxime was seen primarily among strains expressing high levels of class I or IV beta-lactamase. Resistance to cefixime was seen only among strains expressing high levels of class I enzymes. Neither cefixime nor cefuroxime was a strong inducer of class I beta-lactamases, although enzyme induction did appear to play a role in cefuroxime resistance in a strain of Serratia marcescens. The consistently greater activity of cefixime over cefuroxime was found not to be due to greater drug permeation into the cell. Rather, it appeared to result from the high affinity of the drug for target enzymes.