Activity of gatifloxacin compared to those of five other quinolones versus aerobic and anaerobic isolates from skin and soft tissue samples of human and animal bite wound infections

Ubiquitous Nature of Fluoroquinolones: The Oscillation between Antibacterial and Anticancer Activities

Fluoroquinolones are synthetic antibacterial agents that stabilize the ternary complex of prokaryotic topoisomerase II enzymes (gyrase and Topo IV), leading to extensive DNA fragmentation and bacteria death. Despite the similar structural folds within the critical regions of prokaryotic and eukaryotic topoisomerases, clinically relevant fluoroquinolones display a remarkable selectivity for prokaryotic topoisomerase II, with excellent safety records in humans. Typical agents that target human topoisomerases (such as etoposide, doxorubicin and mitoxantrone) are associated with significant toxicities and secondary malignancies, whereas clinically relevant fluoroquinolones are not known to exhibit such propensities. Although many fluoroquinolones have been shown to display topoisomerase-independent antiproliferative effects against various human cancer cells, those that are significantly active against eukaryotic topoisomerase show the same DNA damaging properties as other topoisomerase poisons. Empirical models also show that fluoroquinolones mediate some unique immunomodulatory activities of suppressing pro-inflammatory cytokines and super-inducing interleukin-2. This article reviews the extended roles of fluoroquinolones and their prospects as lead for the unmet needs of "small and safe" multimodal-targeting drug scaffolds.

A Review of New Fluoroquinolones : Focus on their Use in Respiratory Tract Infections

The new respiratory fluoroquinolones (gatifloxacin, gemifloxacin, levofloxacin, moxifloxacin, and on the horizon, garenoxacin) offer many improved qualities over older agents such as ciprofloxacin. These include retaining excellent activity against Gram-negative bacilli, with improved Gram-positive activity (including Streptococcus pneumoniae and Staphylococcus aureus). In addition, gatifloxacin, moxifloxacin and garenoxacin all demonstrate increased anaerobic activity (including activity against Bacteroides fragilis). The new fluoroquinolones possess greater bioavailability and longer serum half-lives compared with ciprofloxacin. The new fluoroquinolones allow for once-daily administration, which may improve patient adherence. The high bioavailability allows for rapid step down from intravenous administration to oral therapy, minimizing unnecessary hospitalization, which may decrease costs and improve quality of life of patients. Clinical trials involving the treatment of community-acquired respiratory infections (acute exacerbations of chronic bronchitis, acute sinusitis, and community-acquired pneumonia) demonstrate high bacterial eradication rates and clinical cure rates. In the treatment of community-acquired respiratory tract infections, the various new fluoroquinolones appear to be comparable to each other, but may be more effective than macrolide or cephalosporin-based regimens. However, additional data are required before it can be emphatically stated that the new fluoroquinolones as a class are responsible for better outcomes than comparators in community-acquired respiratory infections. Gemifloxacin (except for higher rates of hypersensitivity), levofloxacin, and moxifloxacin have relatively mild adverse effects that are more or less comparable to ciprofloxacin. In our opinion, gatifloxacin should not be used, due to glucose alterations which may be serious. Although all new fluoroquinolones react with metal ion-containing drugs (antacids), other drug interactions are relatively mild compared with ciprofloxacin. The new fluoroquinolones gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin have much to offer in terms of bacterial eradication, including activity against resistant respiratory pathogens such as penicillin-resistant, macrolide-resistant, and multidrug-resistant S. pneumoniae. However, ciprofloxacin-resistant organisms, including ciprofloxacin-resistant S. pneumoniae, are becoming more prevalent, thus prudent use must be exercised when prescribing these valuable agents.

Maxillofacial injuries due to animal bites

INTRODUCTION

Animal bites are a significant public health problem, with the majority of bites coming from dogs, cats and humans. These may present as punctures, abrasions, tears, or avulsions. The force and relative bluntness of the teeth also increases the possibility of a crush injury with devitalized tissue .The clinical presentation and appropriate treatment of infected bite wounds vary according to the animal and causative organisms. These wounds have always been considered complex injuries contaminated with a unique polymicrobial inoculum.

MATERIALS

This article reviews animal bite wound incidence, bacteriology, risk factors for complications, evaluation components, recommended treatment and prevention based on advanced PUBMED search of the English language literature from the years 1970 to present.

CONCLUSION

As the bite wounds are frequently located on the face, an oral and maxillofacial surgeon needs to be familiar with the treatment of animal bites, pitfalls in management and to educate patients on ways to avoid future bite injuries. The management of animal bites is an evidence poor area and most recommendations are based on small case series, microbiological data and expert opinion. The main controversies include whether wounds should or should not undergo primary closure and the use of prophylactic antimicrobials.

Postoperative care of the facial laceration

The purpose of this investigation is to examine factors involved in the postoperative care of traumatic lacerations. An evidence-based comprehensive literature review was conducted. There are a limited number of scientifically proven studies that guide surgeons and emergency room physicians on postoperative care. Randomized controlled trials must be conducted to further standardize the postoperative protocol for simple facial lacerations.

Cellulitis and bacteremia caused by Bergeyella zoohelcum

Bergeyella zoohelcum is a rod-shaped, aerobic, Gram-negative, non-motile and non-saccharolytic bacterium. It is frequently isolated from the upper respiratory tract of dogs, cats and other mammals. Clinically, B. zoohelcum has been known to cause cellulitis, leg abscess, tenosynovitis, septicemia, pneumonia and meningitis, and is associated with animal bites. In addition, food-borne transmission was considered in a recent case report. We report a 73-year-old man with liver cirrhosis who had no history of dog bite but had dog exposure, who developed cellulitis of the left lower leg and B. zoohelcum was isolated from blood culture. This patient, without evidence of polymicrobial infection, was treated with cefazolin and gentamicin with a good outcome. B. zoohelcum is a zoonotic pathogen that may cause bacteremia in patients with underlying disease such as liver cirrhosis; it can be treated with a beta-lactam or quinolone.

Levofloxacin for the treatment of community-acquired pneumonia

New respiratory fluoroquinolones (FQs), such as levofloxacin, offer many improved qualities over older agents, such as ciprofloxacin. These include retaining excellent Gram-negative bacilli activity, with improved Gram-positive activity. New FQ-like levofloxacin possesses greater bioavailabilty and a longer serum half-life compared with ciprofloxacin, allowing for once-daily dosing, which may improve patient adherence. The high bioavailability of levofloxacin allows for rapid step-down from intravenous administration to oral therapy, minimizing unnecessary hospitalization, which may decrease costs and improve patient quality of life. Levofloxacin has been evaluated for the treatment of community-acquired pneumonia (CAP) in numerous randomized clinical trials. Most published studies have used the 500 mg dose, although more recent studies have investigated the 750 mg dose once daily. These trials demonstrate that levofloxacin is effective and safe for the treatment of CAP, displaying relatively mild adverse effects that are more or less comparable with ciprofloxacin. Levofloxacin has much to offer in terms of bacterial eradication, including for resistant respiratory pathogens. However, ciprofloxacin-resistant organisms are becoming more prevalent so prudence must be exercised when prescribing this agent.

Children hospitalized with skin and soft tissue infections: a guide to antibacterial selection and treatment

Skin and soft tissue infections in children are an important cause for hospitalization. A thorough history and physical examination can provide clues to the pathogens involved. Collection of purulent discharge from lesions should be completed prior to initiating antimicrobial therapy, and results of bacteriologic studies (Gram stain and culture) should guide therapeutic decisions. The main pathogens involved in these infections are Staphylococcus aureus and group A beta-hemolytic streptococci, but enteric organisms also play a role especially in nosocomial infections. Increasing antibacterial resistance is becoming a major problem in the treatment of these infections worldwide. Specifically, the rise of methicillin-resistant S. aureus and glycopeptide-resistant S. aureus pose challenges for the future. Infections of the skin and soft tissues can be broadly classified based on the extent of tissue involvement. Superficial infections such as erysipelas, cellulitis, bullous impetigo, bite infections, and periorbital cellulitis may require hospitalization and parenteral antibacterials. Deeper infections such as orbital cellulitis, necrotizing fasciitis, and pyomyositis require surgical intervention as well as parenteral antibacterial therapy. Surgery plays a key role in the treatment of abscesses and for the debridement of necrotic tissue in deep infections. Intravenous immunoglobulin, as an adjunctive therapy, can be helpful in treating necrotizing fasciitis. For most infections an antistaphylococcal beta-lactam antibacterial is first-line therapy. Third-generation cephalosporins and beta-lactam/beta-lactamase inhibitor antibacterials as well as clindamycin or metronidazole are often required to provide broad-spectrum coverage for polymicrobial infections.Special populations, such as immunocompromised children, those with an allergy to penicillins, and those that acquire infections in hospitals, require specific antibacterial strategies. These usually involve broader antimicrobial coverage with increased Gram-negative (including antipseudomonal) and anerobic coverage. In patients with a true allergy to penicillins, clindamycin and vancomycin play an important role in treating Gram-positive infections. Newer antibacterial agents, such as linezolid and quinupristin/dalfopristin, are increasingly being studied in children for the treatment of skin and soft tissue infections. These agents hold promise for the future especially in the treatment of highly resistant, Gram-positive organisms such as methicillin-resistant S. aureus, vancomycin-resistant S. aureus, and vancomycin-resistant enterococci.

Fluoroquinolones and Anaerobes

The usefulness of fluoroquinolones for the treatment of mixed aerobic and anaerobic infections has been investigated since these agents started being used in clinical practice. Newer compounds have increased in vitro activity against anaerobes, but clinically relevant susceptibility breakpoints for these bacteria have not been established. Pharmacodynamic analyses and corroboration by new data from clinical trials have enhanced our knowledge concerning the use of fluoroquinolones to treat selective anaerobic pathogens. These studies suggest that newer agents could be useful in the treatment of several types of mixed aerobic and anaerobic infections, including skin and soft-tissue, intra-abdominal, and respiratory infections. The major concerns with expanding the use of fluoroquinolones to treat anaerobic infections have been reports of increasing resistance in Bacteroides group isolates and the impact of these antibiotics on the incidence of Clostridium difficile-associated disease.

Activity of gatifloxacin tested against isolates from pediatric patients: report from the SENTRY Antimicrobial Surveillance Program (North America, 1998-2003)

The SENTRY Antimicrobial Surveillance Program has monitored the activity of antimicrobial agents worldwide since 1997. The increasing number of clinical failures with established anti-infectives (penicillins, other beta-lactams, macrolides) among pediatric patients has stressed the importance for alternative therapeutic options. Ciprofloxacin has been recently approved for expanded use as treatment of complicated urinary tract infections in children, and gatifloxacin has been used successfully in clinical trials in selected children with severe or refractory otitis media. We evaluated the activity of gatifloxacin against strains isolated from children < 7 years of age and compared this to the general patient population (all ages included) using the SENTRY Program database. A total of 59826 North American isolates were collected, of which 4641 were from children (< 7 years old); all isolates were tested using reference broth microdilution methods. In contrast to the general population (GP), gatifloxacin resistance rates were very low among isolates from this younger patient group. Gatifloxacin susceptibility rates were > 84% for all pathogens evaluated in younger patients. All Streptococcus pneumoniae strains from children < 7 years old were susceptible to gatifloxacin, and susceptibility among the Enterobacteriaceae species was > 98%. The greatest difference in susceptibility rates between the younger children and the GP was observed among nonfermentative gram-negative bacilli (95.0-100% versus 64.8-83.7%, respectively) and Enterococcus faecalis (94.7% versus 58.4%). Gatifloxacin susceptibilities of Pseudomonas aeruginosa and Acinetobacter spp. isolates from the pediatric population were > or = 95% (> 97% for ciprofloxacin) compared to the GP at only 64.8-69.1%. In conclusion, gatifloxacin remains very active against bacterial isolates from children < 7 years, indicative of the limited exposure of this population to fluoroquinolones. Continued resistance surveillance will be necessary to monitor the activity of the fluoroquinolone class as they are introduced for specific clinical indications into the pediatric age groups, especially if re-studied against S. pneumoniae (refractory otitis media) and P. aeruginosa (cystic fibrosis associated pneumonia).

Management of human and animal bite wounds: an overview

Serious infections can result from wounds that are caused by bites from animals and humans. Organisms recovered from bite wounds generally originate from the oral cavity of the biting animal, as well as from the patient's skin flora. Anaerobes have been isolated from animal and human bite wound infections, especially those associated with abscess formation. In addition to local wound infections, common complications, such as lymphangitis, septic arthritis, tenosynovitis, and osteomyelitis, and uncommon complications, such as endocarditis, meningitis, brain abscess, and sepsis, may occur. Wound management includes proper local care and, when needed, antimicrobial therapy.

Broth microdilution and disk diffusion tests for susceptibility testing of Pasteurella species isolated from human clinical specimens

Broth microdilution and disk diffusion susceptibility testing were performed on 73 strains of Pasteurella species isolated from human infections and on five American Type Culture Collection strains of Pasteurella species. Both methods appear reliable for testing susceptibilities of Pasteurella species.

The use of fluoroquinolones in the treatment of skin infections

Fluoroquinolones have been studied for both uncomplicated and complicated skin and skin structure infections. Their broad spectrum, rapid bactericidal activity, extensive tissue penetration, excellent bioavailability and ease of administration have made these drugs a common choice for many infectious diseases, including skin infections. Extensive research has shown the fluoroquinolones to be as effective as beta-lactam antibiotics in managing a spectrum of diseases including erysipelas, cellulitis, impetigo, surgical wounds and diabetic foot infections. However, resistance to the fluoroquinolones has increased among the staphylococci, streptococci, Enterobacteriaceae and other important Gram-negative bacilli. Resistance has been linked directly to the widespread use of these compounds. Despite their appeal in the treatment of both uncomplicated and complicated skin infections, the fluoroquinolones should be reserved as alternatives to beta-lactams and other antibiotics or as empirical therapy in complicated infections until pathogens have been identified and drug regimens can be focused.

In vitro activity of gatifloxacin, a new fluoroquinolone, against 204 anaerobes compared to seven other compounds

The activity of gatifloxacin, a new fluoroquinolone derivative, was compared with the activities of ciprofloxacin, levofloxacin, amoxicillin, amoxicillin-clavulanate, imipenem, clindamycin and metronidazole against 204 anaerobes isolated from clinical specimens, by MIC determination, using the reference agar dilution method. When determining the overall activity against anaerobes, the MIC50/90 (mg/L) values were amoxicillin 16/>64, amoxicillin-clavulanate 0.125/1, imipenem 0.25/0.5, clindamycin 0.5/>256, metronidazole 1/8, ciprofloxacin 2/32, levofloxacin 1/8 and gatifloxacin 0.5/4. The broad in vitro spectrum of gatifloxacin is promising for the treatment of mixed anaerobic infections, especially those of the respiratory tract, ear, sinus, skin and soft tissues, and bite wounds. These data suggest that gatifloxacin may have a clinical role in the treatment of infections in which anaerobic pathogens are involved.

A practical guide to the treatment of complicated skin and soft tissue infections

Complicated skin and soft tissue infections (SSTIs) remain a common reason for hospitalisation. Optimal management of complicated SSTIs begins with a physical examination, and obtaining the complete social and medical history of the patient. Empirical intravenous antibacterial therapy is guided by expected pathogens, patient factors and diagnostic procedure reports, such as the Gram-stained smear of discharge or exudates. The majority of community-acquired SSTIs are caused by Staphylococcus aureus and beta-haemolytic streptococci. On the basis of recent surveillance data, 80-90% of these pathogens remain susceptible to cefazolin or oxacillin. Consequently, a first generation cephalosporin or an antistaphylococcal penicillin remains the first line empirical therapy for community-acquired skin and soft tissue infections. Vancomycin may be an appropriate alternative when vancomycin-resistant S. aureus is highly suspected on the basis of patient history and co-morbid conditions. With the global emergence and spread of macrolide-resistant S. aureus and beta-haemolytic streptococci, clindamycin rather than a macrolide is the recommended agent for empirical antibacterial therapy of community-acquired SSTIs in penicillin-allergic patients. Nosocomial complicated SSTIs are predominantly caused by S. aureus, Pseudomonas aeruginosa, Enterococcus spp., Escherichia coli and other Enterobacteriaceae. Piperacillin/tazobactam with or without vancomycin is the preferred agent for empirical treatment depending on local resistance statistics. The newer fluoroquinolones may have a role in the treatment of complicated SSTIs, especially in penicillin-allergic patients. More clinical studies are needed before a formal recommendation can be made. Many of the newer antimicrobial agents such as the carbapenems, oxazolidinones and streptogramins have been shown to be effective for the treatment of complicated SSTIs. However, because of their proven activity against highly resistant organisms including methicillin-resistant S. aureus and vancomycin-resistant enterococci (oxazolidinones and streptogramins), and Gram-negative bacilli producing extended spectrum beta-lactamases (carbapenems), these antibacterials should be reserved for life-threatening situations and/or when resistant pathogens are suspected. Complicated skin and soft tissue infections are often associated with exudates, ulcerations, fluid collections or abscesses. Adequate debridement of devitalized tissues and drainage of abscesses and fluid collections in addition to systemic antibacterial therapy is an integral part of appropriate management.

In vitro activities of new fluoroquinolones against Campylobacter jejuni and Campylobacter coli isolates obtained from humans in 1980 to 1982 and 1997 to 2001

The antibacterial activities of three newly developed fluoroquinolones (gatifloxacin, levofloxacin, and moxifloxacin) against a total of 307 gastrointestinal human isolates of Campylobacter jejuni and Campylobacter coli collected during 1980 to 1982 and 1997 to 2001 were examined and compared to those of ciprofloxacin and the unrelated antibacterial agents, clarithromycin, erythromycin, and tetracycline by using the agar plate dilution method. All of the fluoroquinolones exhibited a good activity against Campylobacter, and some of them were more active than ciprofloxacin, the macrolides, and tetracycline. Among the fluoroquinolones, gatifloxacin and moxifloxacin showed the highest anticampylobacter activity, with MICs at which 50% of the isolates tested are inhibited (MIC(50)s) and MIC(90)s of 0.125 and 4 microg/ml, respectively; the MIC(50) for both levofloxacin and ciprofloxacin was 0.25, and the MIC(90)s were 16 and 32 microg/ml, respectively. About 30% of the strains were found to be resistant to at least one fluoroquinolone. Resistance to gatifloxacin occurred in 9.8% of the isolates tested, and resistance to the other fluoroquinolones occurred in 19.9 to 27.4% of the isolates tested; the frequency of cross-resistance was 35.7 to 100%. An increase in fluoroquinolone resistance from 0% in 1980 to 1982 to 11.8 to 29% in 1997 and 1998, 8.2 to 31.8% in 1999 and 2000, and 12.1 to 30.3% in 2001 was found. A total of 61.4 to 73.2% of the C. jenuni strains resistant to erythromycin, clarithromycin, and/or tetracycline were susceptible to fluoroquinolones; gatifloxacin showed the highest percentage of inhibition. These results show that the newer fluoroquinolones with their potent activity could be used to treat infections with C. jejuni and C. coli. However, when these drugs are used, one must consider the increase in resistance and the high cross-resistance to these antimicrobial agents.

Bite Wound Infections

Patients with mammalian bite wounds account for hundreds of thousands of emergency department, urgent care center, and physician office visits in the United States each year. The types of wounds encountered by physicians range from insignificant scratches to life-threatening neck and facial injuries. Infectious complications of bite wounds are common, and the consequences of these infections are significant and sometimes disabling. This article reviews the infectious complications of cat, dog, and human bite wounds. The prevention of tetanus and rabies virus infection, the appropriate antimicrobial treatment of bacterial infections, and the frequent need for surgical consultation and intervention are emphasized.

Review of the in vitro activity and potential clinical efficacy of levofloxacin in the treatment of anaerobic infections

The activity of levofloxacin against aerobic bacteria has been well documented both in vitro and clinically, but its anaerobic activity has been infrequently studied. This new fluoroquinolone exhibits good in vitro activity (MIC(S) < or =2.0 microg/mL) against many anaerobic pathogens associated with acute sinusitis, bite wounds, and other soft-tissue infections. It is less active against Bacteroides fragilis (MIC (90)=2-4 microg/mL ) and has poor inhibitory activity against non-fragilis B. fragilis group species that are associated with gastrointestinal and genitourinary tract infections. Levofloxacin does not antagonize the in vitro activity of clindamycin and metronidazole and often provides additive or synergistic activity against anaerobic bacteria with these agents. In pharmacodynamic models, levofloxacin exhibits rapid bactericidal activity at 2-4 times the MIC of anaerobic bacteria. Prolonged killing is observed when the area-under-the concentration-time-curve to MIC ratio is greater than 40. In clinical efficacy trials, levofloxacin has been effective in the treatment of patients with gynecologic, skin and skin-structure, and bone infections involving anaerobic pathogens. Both micro-biologic and pharmacodynamic studies support further evaluations of levofloxacin in the treatment of selective mixed aerobic/anaerobic infections.

Microbiology and management of human and animal bite wound infections

This article describes the microbiology, diagnosis, and management of human and animal bite wound infections. Various organisms can be recovered from bite wounds that generally result from aerobic and anaerobic microbial flora of the oral cavity of the biting animal, rather than the victim's own skin flora. The role of anaerobes in bite wound infections has been increasingly appreciated. Anaerobes were isolated from more than two thirds of human and animal bite wound infections, especially those associated with abscess formation. This article describes several of the organisms found in the bites of various species. In addition to local wound infection, other complications may occur, including lymphangitis, local abscess, septic arthritis, tenosynovitis, and osteomyelitis. Rare complications include endocarditis, meningitis, brain abscess, and sepsis with disseminated intravascular coagulation, especially in immunocompromised individuals. Wound management includes the administration of proper local care and the use of proper antimicrobial agents when needed.

The Role of Fluoroquinolones in the Treatment of Skin and Soft Tissue Infection

Skin and soft tissue infections vary widely in their nature and severity, and their nomenclature is complex. Most are readily recognized and easily treated, but more severe infections may masquerade in forms similar to those of more innocent infections, causing delay in diagnosis and treatment that may result in loss of limb or life. Antimicrobial therapy is clearly beneficial for both recovery from these infections as well as preventing disease progression. The fluoroquinolones are potent broad-spectrum antimicrobial agents. The older fluoroquinolones mainly have excellent in vitro activity against gram-negative bacilli and borderline activity against clinically important gram-positive organisms, but newer fluoroquinolones were developed to have enhanced activity against both gram-positive and anaerobic organisms while retaining broad-spectrum anti-gram-negative activity. Several comparative trials using fluoroquinolones suggest that the efficacy of these agents is similar to that of b-lactam antimicrobial agents. Additional clinical trials are necessary to determine the overall role of newer fluoroquinolones as alternatives for skin and soft tissue infections.

Eikenella corrodens in subgingival plaque: relationship to age and periodontal condition

BACKGROUND

The purpose of this study was to determine the prevalence and distribution of Eikenella corrodens (E. corrodens) in subgingival plaque in different age and periodontitis groups and to examine whether its presence is related to periodontal diseases.

METHODS

A total of 273 subgingival plaque samples from 213 periodontitis patients and 60 healthy subjects were assessed. Smears from each plaque sample were made and E. corrodens was detected by means of indirect immunofluorescent technique. Mean percentage of E. corrodens per total bacteria (distribution) was calculated in each sample. The prevalence (% of positive samples) and distribution of E. corrodens were statistically analyzed based on age or diagnosis by means of Fisher's exact test and analysis of variance (ANOVA).

RESULTS

Prevalence of E. corrodens decreased by age in the healthy control group; however, prevalence did not change in periodontitis groups. Distribution of E. corrodens was highest in juvenile periodontitis (JP) (2.3 +/- 1.5%) followed by post-JP (1.7 +/- 2.1%), prepubertal periodontitis (1.4 +/- 1.1%), rapidly progressive periodontitis (0.8 +/- 0.7%), adult periodontitis (0.7 +/- 0.6%), and healthy subjects (0.3 +/- 0.3%) (ANOVA, P<0.0001). The <20-year-old age group with periodontitis showed the highest distribution of E. corrodens (2.2 +/- 1.6%) compared to the older age groups who were either healthy or had periodontitis (ANOVA, P<0.0001).

CONCLUSIONS

Since the distribution of E. corrodens is significantly higher in JP, post-JP, and PP, E. corrodens might play an important role in the occurrence or progression of periodontitis in young patients.

The role of fluoroquinolones in skin and skin structure infections

Skin and skin structure infections encompass a broad range of clinical presentations and disease severity. Antimicrobial therapy is clearly beneficial for both recovery from these infections as well as preventing disease progression. Fluoroquinolones are potent broad spectrum antimicrobial agents with the older agents characterized as having broad spectrum anti-Gram-negative activity, borderline activity against clinically important Gram-positive pathogens and little or no anti-anaerobic bacteria activity. In contrast, the new quinolones are characterized by having enhanced activity against Gram-positive pathogens, anti-anaerobic activity and they remain highly active against aerobic-Gram-negative bacilli. Several fluoroquinolones have been evaluated for the treatment of uncomplicated skin and soft tissue infection, difficult skin and soft tissue infection and serious skin and skin structure infections. Clinical cure rates were found to be equivalent to comparators suggesting a role for the fluoroquinolone in treating these infections. It may be necessary to use some fluoroquinolones in combination with anti-anaerobic agents for those infections with mixed aerobic and anaerobic pathogens. Some additional clinical trials are necessary to identify the full potential of newer fluoroquinolones for skin and skin structure infections. At present, quinolones are, in general, equivalent to beta-lactam agents in the treatment of skin and soft tissue infection.

A critical review of the fluoroquinolones: focus on respiratory infections

The new fluoroquinolones (clinafloxacin, gatifloxacin, gemifloxacin, grepafloxacin, levofloxacin, moxifloxacin, sitafloxacin, sparfloxacin and trovafloxacin) offer excellent activity against Gram-negative bacilli and improved Gram-positive activity (e.g. against Streptococcus pneumoniae and Staphylococcus aureus) over ciprofloxacin. Ciprofloxacin still maintains the best in vitro activity against Pseudomonas aeruginosa. Clinafloxacin, gatifloxacin, moxifloxacin, sitafloxacin, sparfloxacin and trovafloxacin display improved activity against anaerobes (e.g. Bacteroides fragilis) versus ciprofloxacin. All of the new fluoroquinolones display excellent bioavailability and have longer serum half-lives than ciprofloxacin allowing for once daily dose administration. Clinical trials comparing the new fluoroquinolones to each other or to standard therapy have demonstrated good efficacy in a variety of community-acquired respiratory infections (e.g. pneumonia, acute exacerbations of chronic bronchitis and acute sinusitis). Limited data suggest that the new fluoroquinolones as a class may lead to better outcomes in community-acquired pneumonia and acute exacerbations of chronic bronchitis versus comparators. Several of these agents have either been withdrawn from the market, had their use severely restricted because of adverse effects (clinafloxacin because of phototoxicity and hypoglycaemia; grepafloxacin because of prolongation of the QTc and resultant torsades de pointes; sparfloxacin because of phototoxicity; and trovafloxacin because of hepatotoxicity), or were discontinued during developmental phases. The remaining fluoroquinolones such as gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin have adverse effect profiles similar to ciprofloxacin. Extensive post-marketing safety surveillance data (as are available with ciprofloxacin and levofloxacin) are required for all new fluoroquinolones before safety can be definitively established. Drug interactions are limited; however, all fluoroquinolones interact with metal ion containing drugs (eg. antacids). The new fluoroquinolones (gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin) offer several advantages over ciprofloxacin and are emerging as important therapeutic agents in the treatment of community-acquired respiratory infections. Their broad spectrum of activity which includes respiratory pathogens such as penicillin and macrolide resistant S. pneumoniae, favourable pharmacokinetic parameters, good bacteriological and clinical efficacy will lead to growing use of these agents in the treatment of community-acquired pneumonia, acute exacerbations of chronic bronchitis and acute sinusitis. These agents may result in cost savings especially in situations where, because of their potent broad-spectrum activity and excellent bioavailability, they may be used orally in place of intravenous antibacterials. Prudent use of the new fluoroquinolones will be required to minimise the development of resistance to these agents.

Gatifloxacin: a review of its use in the management of bacterial infections

Gatifloxacin is an 8-methoxy fluoroquinolone antibacterial agent. The drug has a broader spectrum of antibacterial activity than the older fluoroquinolones (e.g. ciprofloxacin) and shows good activity against many Gram-positive and Gram-negative pathogens, atypical organisms and some anaerobes. Notably, gatifloxacin is highly active against both penicillin-susceptible and -resistant strains of Streptococcus pneumoniae, a common causative pathogen in community-acquired pneumonia (CAP), acute sinusitis and acute bacterial exacerbations of bronchitis. Gatifloxacin is absorbed well from the gastrointestinal tract (oral bioavailability is almost 100%). Therefore, patients can be switched from intravenous to oral therapy without an adjustment in dosage. High concentrations of gatifloxacin are achieved in plasma and target tissues/fluids. Gatifloxacin has a long plasma elimination half-life, thus allowing once-daily administration. Few clinically significant interactions between gatifloxacin and other drugs have been reported. In patients with CAP, clinical response rates in recipients of intravenous/oral gatifloxacin 400 mg/day ranged from 86.8 to 98.0% and rates of bacterial eradication ranged from 83.1 to 100% (up to 28 days post-treatment). Gatifloxacin showed efficacy similar to that of amoxicillin/clavulanic acid, ceftriaxone (with or without erythromycin) with or without stepdown to clarithromycin, levofloxacin or clarithromycin. Gatifloxacin was as effective as clarithromycin or amoxicillin/clavulanic acid, and was significantly more effective (in terms of clinical response; p < 0.035) than 7 to 10 days' treatment with cefuroxime axetil in the treatment of acute exacerbations of chronic bronchitis. In acute sinusitis, gatifloxacin showed clinical efficacy similar to that of clarithromycin, trovafloxacin or amoxicillin/clavulanic acid. Genitourinary infections were also successfully treated with gatifloxacin. Gatifloxacin is generally well tolerated. Its tolerability profile was broadly similar to those of comparator agents in comparative trials. The most common adverse events are gastrointestinal symptoms (oral formulation) and injection site reactions.

CONCLUSIONS

Gatifloxacin has an extended spectrum of antibacterial activity and provides better coverage of Gram-positive organisms (e.g. S. pneumoniae) than some older fluoroquinolones. The drug has favourable pharmacokinetic properties, is administered once daily and is at least as well tolerated as other fluoroquinolones. Gatifloxacin is a useful addition to the fluoroquinolones currently available for use in the clinical setting and has an important role in the management of adult patients with various bacterial infections. As with other fluoroquinolones, careful control of gatifloxacin usage in the community is important in order to prevent the emergence of bacterial resistance and thus preserve the clinical value of this agent.

Periodontal bacteria in rabbit mandibular and maxillary abscesses

Despite the high incidence of odontogenic abscesses in pet rabbits, published data on the bacteriology of these infections are lacking, and clinical cultures are often ambiguous, making antibiotic choices difficult. In order to define the bacteriology of these infections, 12 rabbit mandibular and maxillary abscesses were cultured aerobically and anaerobically. All specimens yielded pathogenic bacteria, including Fusobacterium nucleatum, Prevotella heparinolytica, Prevotella spp., Peptostreptococcus micros, Streptococcus milleri group, Actinomyces israelii, and Arcanobacterium haemolyticum. These organisms are consistent with the characterized bacteriology of periodontal disease in human and other mammalian studies. The isolates were tested against 10 antimicrobial agents commonly used to treat rabbits; 100% of the strains tested were susceptible to clindamycin, 96% were susceptible to penicillin and ceftriaxone, 54% were susceptible to ciprofloxacin, and only 7% were susceptible to trimethoprim-sulfamethoxazole.

Once-daily oral gatifloxacin versus oral levofloxacin in treatment of uncomplicated skin and soft tissue infections: double-blind, multicenter, randomized study

This was a double-blind, multicenter study in which 410 adults (> or =18 years of age) with uncomplicated skin and soft tissue infections (SSTIs) were randomized to receive either 400 mg of gatifloxacin orally once daily or 500 mg of levofloxacin orally once daily for 7 to 10 days. The study protocol called for four assessments-before and during treatment, at the end of treatment, and posttreatment. Efficacy evaluations included clinical response and bacterial eradication rates. Of 407 treated patients, 202 (108 women, 94 men) received gatifloxacin and 205 (111 women, 94 men) received levofloxacin. For clinically evaluable patients, the cure rates were 91% for gatifloxacin and 84% for levofloxacin (95% confidence interval [CI] for the difference, -2.0 to 15.2%). Clinical cure rates for microbiologically evaluable patients were 93% for gatifloxacin and 88% for levofloxacin (95% CI for the difference, -6.5 to 16.8%). The bacterial eradication rate was 92% for each group, with gatifloxacin eradicating 93% of the methicillin-susceptible Staphylococcus aureus isolates and levofloxacin eradicating 91% of them. Both drugs were well tolerated. Most of the adverse events were mild to moderate, and nausea was the most common adverse event in each treatment arm. Once-daily oral gatifloxacin (400 mg) is clinically efficacious and well tolerated compared with once-daily levofloxacin (500 mg) for the treatment of patients with uncomplicated SSTIs.

Anaerobic pleuropulmonary infection

Obligate anaerobes are the predominant constituents of normal oropharyngeal flora and produce pleuropulmonary infection in patients who are prone to aspirate. Obtaining material from these patients for culture from the site of infection that is uncontaminated by normal flora is problematic. In-vitro cultivation of obligate anaerobes requires rigorous anaerobic techniques and susceptibility testing of obligate anaerobes is not standardized in many clinical microbiology laboratories. Few clinical trials of drugs have been done in patients with laboratory documented or putative anaerobic pulmonary infection. For these reasons the diagnosis and therapy of anaerobic pulmonary infection are frequently empirical and guided by published studies of in-vitro activity against collected clinical isolates. Several new drugs that have in-vitro activity against obligate anaerobes have recently become available for empirical treatment of pneumonia.

Gatifloxacin, an advanced 8-methoxy fluoroquinolone

Gatifloxacin is a new 8-methoxy-fluoroquinolone antibiotic approved for use in the United States in December 1999. It has a broad spectrum of activity with potent activity against gram-positive bacteria, including penicillin-resistant Streptococcus pneumoniae, as well as excellent activity against gram-negative and atypical organisms. Gatifloxacin is available in both oral and injectable forms and is administered once/day. Bioavailability is 96%, with a plasma half-life of approximately 8 hours in individuals with normal renal function. Elimination is primarily renal excretion of unchanged drug with no cytochrome P450-mediated metabolism. The drug is distributed extensively into tissues and fluids and has a favorable pharmacodynamic profile against important pathogens. It had excellent efficacy in clinical studies of acute sinusitis, acute bacterial exacerbations of chronic bronchitis, community-acquired pneumonia, complicated and uncomplicated urinary tract infections and pyelonephritis, skin and skin structure infections, and uncomplicated gonococcal infections. The agent is well tolerated, with no evidence of hepatic, cardiac, or phototoxicity noted thus far. Drug interactions are uncommon; however, like other fluoroquinolones, coadministration with multivalent cations should be avoided due to significantly decreased absorption. Gatifloxacin should prove to be a safe and effective agent for a wide variety of infections.

Gatifloxacin

Each month, subscribers to The Formulary® Monograph Service receive five to six researched monographs on drugs that are newly released or are in late Phase III trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation (DUE) is also provided each month. The monographs are published in printed form and on diskettes that allow customization. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board called The Formulary Information Exchange (The F.I.X). All topics pertinent to clinical pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The April 2000 Formulary monographs are alsosetron, oxcarbazepine, mitoxantrone, cevimeline HCl, and cicloporox. The DUE is on alosetron.

In vitro activities of gatifloxacin, two other quinolones, and five nonquinolone antimicrobials against obligately anaerobic bacteria

The activity of the new fluoroquinolone gatifloxacin was compared with those of other quinolones and antimicrobial agents of other classes against 294 anaerobes by the broth microdilution technique. For all strains tested, gatifloxacin MICs at which 50 and 90% of the isolates were inhibited were 0.5 and 2 mg/liter, respectively, and were 3 to 4 dilution steps lower than, e.g., ciprofloxacin.