Role of quinolones in the treatment of diarrhoeal diseases

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.

Infectious Enteritis

Initial management of acute infectious enteritis should focus on fluid and electrolyte repletion and symptomatic care. A decision to prescribe empiric antibiotic therapy should rest on clinical or epidemiologic features of the illness that suggest a treatable bacterial origin or a high-risk host. This decision should be reinforced by the detection of leukocytes or blood in the stool. If empiric therapy is indicated, a quinolone is generally the best initial choice. A stool culture yielding an enteropathogen should generally be specifically treated. A possible exception is uncomplicated Salmonella gastroenteritis in an otherwise healthy host. Nosocomial diarrhea is caused by Clostridium difficile in a minority of cases. Because diagnostic studies for this pathogen are sufficiently sensitive and specific, empiric antibiotic treatment for C. difficile is seldom indicated. Diarrhea in AIDS patients is best worked up and managed in a stepwise fashion, beginning with simple measures. Endoscopy or surgery are seldom indicated in the evaluation and management of infectious enteritis.

Comparative efficacy of cefixime and ampicillin-sulbactam in shigellosis in children

Shigellosis is still an important health problem in developing and underdeveloped countries as it is resistance to commonly used antibiotics including ampicillin, trimethoprim-sulfamethoxazole, chloramphenicol and tetracycline. Between May 1996 and October 1996, in a prospective randomized double-blind trial, cefixime was compared with ampicillin-sulbactam, both given orally for a period of 5 days, for the treatment of 80 children with acute bloody diarrhea. Forty patients were treated with a single-dose (8 mg/kg per day) of cefixime and the other 40 patients were given three doses of 100 mg/kg per day of ampicillin-sulbactam. After identification of Shigella organisms in stool specimens, nine patients in the cefixime receiving group and six patients in the ampicillin-sulbactam receiving group were excluded from the study. Differences in average age, sex and weight between the cefixime and ampicillin-sulbactam group were statistically meaningless (P > 0.05). Fever and bloody diarrhea were universal features. The efficacy of cefixime was found to be better than ampicillin-sulbactam. Patients given cefixime had a shorter duration of fever (P < 0.01), shorter duration to disappearance of blood in the stool (P < 0.01), reduced time with diarrhea (P < 0.01) and reduced hospitalization time during the 5 study days (P < 0.01) than patients given ampicillin-sulbactam. No adverse effects were observed in the two study groups. This controlled trial showed good efficacy with cefixime compared to ampicillin-sulbactam in the treatment of shigellosis. Single-dose daily oral therapy with cefixime also showed good tolerability. Cefixime should be considered as an alternative drug of choice for shigellosis in children.

Ciprofloxacin. An updated review of its pharmacology, therapeutic efficacy and tolerability

Ciprofloxacin is a broad spectrum fluoroquinolone antibacterial agent. Since its introduction in the 1980s, most Gram-negative bacteria have remained highly susceptible to this agent in vitro; Gram-positive bacteria are generally susceptible or moderately susceptible. Ciprofloxacin attains therapeutic concentrations in most tissues and body fluids. The results of clinical trials with ciprofloxacin have confirmed its clinical efficacy and low potential for adverse effects. Ciprofloxacin is effective in the treatment of a wide variety of infections, particularly those caused by Gram-negative pathogens. These include complicated urinary tract infections, sexually transmitted diseases (gonorrhoea and chancroid), skin and bone infections, gastrointestinal infections caused by multiresistant organisms, lower respiratory tract infections (including those in patients with cystic fibrosis), febrile neutropenia (combined with an agent which possesses good activity against Gram-positive bacteria), intra-abdominal infections (combined with an antianaerobic agent) and malignant external otitis. Ciprofloxacin should not be considered a first-line empirical therapy for respiratory tract infections if penicillin-susceptible Streptococcus pneumoniae is the primary pathogen; however, it is an appropriate treatment option in patients with mixed infections (where S. pneumoniae may or may not be present) or in patients with predisposing factors for Gram-negative infections. Clinically important drug interactions involving ciprofloxacin are well documented and avoidable with conscientious prescribing. Recommended dosage adjustments in patients with impaired renal function vary between countries; major adjustments are not required until the estimated creatinine clearance is < 30 ml/min/1.73m2 (or when the serum creatinine level is > or = 2 mg/dl). Ciprofloxacin is one of the few broad spectrum antibacterials available in both intravenous and oral formulations. In this respect, it offers the potential for cost savings with sequential intravenous and oral therapy in appropriately selected patients and may allow early discharge from hospital in some instances. In conclusion, ciprofloxacin has retained its excellent activity against most Gram-negative bacteria, and fulfilled its potential as an important antibacterial drug in the treatment of a wide range of infections. Rational prescribing will help to ensure the continued clinical usefulness of this valuable antimicrobial drug.