Excretion of sulfamethoxazole and trimethoprim into human bile

Changes in the aerobic faecal flora of patients treated with antibiotics for acute intra-abdominal infection

BACKGROUND

An open observational study was performed to investigate changes in the rectal flora and antibiotic susceptibility among faecal bacteria in patients treated with antibiotics for acute intra-abdominal infection.

METHODS

One hundred and forty patients with acute intra-abdominal infection requiring antibiotic treatment and hospitalization were included. Eight surgical units from the southern part of Sweden participated, between January 2006 and November 2007. Antibiotic treatments were according to local guidelines. Rectal swabs were obtained on admission (sample 1) and 2-14 days after the end of antibiotic treatment (sample 2). Aerobic bacteria and yeasts were analysed. The material was divided into 2 groups: 1 group with Enterobacteriaceae and 1 group with non-fermentative Gram-negative bacteria. The susceptibility to antibiotics in each group was compared between samples 1 and 2.

RESULTS

The main finding of this study on patients with severe intra-abdominal infections was a shift in the aerobic faecal flora following antibiotic treatment, from Escherichia coli to other more resistant Enterobacteriaceae, Enterococcus faecium, and yeasts. The susceptibility to cephalosporins and piperacillin-tazobactam decreased in Enterobacteriaceae.

CONCLUSIONS

Following antibiotic treatment, a shift in the aerobic rectal flora to species with intrinsic antibiotic resistance was observed. This indicates that the emergence of resistance is not due to new mutations, but rather to selection of more resistant species. This should be taken into account when designing treatments for secondary intra-abdominal infections.

The pharmacokinetics and safety profile of oral ganciclovir in combination with trimethoprim in HIV- and CMV-seropositive patients

AIMS

We investigated the pharmacokinetics and safety profile of oral ganciclovir coadministered with trimethoprim in HIV-and CMV-seropositive patients.

METHODS

In an open-label, randomized, 3-way crossover study, 12 adult males received oral ganciclovir 1000 mg every 8h, oral trimethoprim 200 mg once daily, or both drugs concomitantly in a sequence of three 7-day treatment periods. Pharmacokinetic parameters were determined and adverse events recorded for each treatment.

RESULTS

The presence of trimethoprim significantly decreased CLr (12.9%, P=0.0068) and increased t1/2 (18.1%, P=0.0378) of ganciclovir. However, these changes are unlikely to be clinically meaningful. There were no statistically significant changes in trimethoprim pharmacokinetic parameters in the presence of ganciclovir, with the exception of a 12.7% increase in Cmin. Ganciclovir was well tolerated when administered alone or in combination with trimethoprin.

CONCLUSIONS

There was no clinically significant pharmacokinetic interaction between oral ganciclovir and trimethoprim when coadministered.

Biliary tract infections: a guide to drug treatment

Initial therapy of acute cholecystitis and cholangitis is directed towards general support of the patient, including fluid and electrolyte replacement, correction of metabolic imbalances and antibacterial therapy. Factors affecting the efficacy of antibacterial therapy include the activity of the agent against the common biliary tract pathogens and pharmacokinetic properties such as tissue distribution and the ratio of concentration in both bile and serum to the minimum inhibitory concentration for the expected micro-organism. Antimicrobial therapy is usually empirical. Initial therapy should cover the Enterobacteriaceae, in particular Escherichia coli. Activity against enterococci is not required since their pathogenicity in biliary tract infections remains unclear. Coverage of anaerobes, in particular Bacteroides spp., is warranted in patients with previous bile duct-bowel anastomosis, in the elderly and in patients in serious clinical condition. In patients with acute cholecystitis or cholangitis of moderate clinical severity, monotherapy with a ureidopenicillin--mezlocillin or piperacillin--is at least as effective as the combination of ampicillin plus aminoglycoside. In severely ill patients with septicaemia, an antibacterial combination is preferable. Therapy with aminoglycosides, mostly for Pseudomonas aeruginosa-related infections, should not exceed a few days because the risk of nephrotoxicity seems to be increased during cholestasis. Relief of biliary obstruction is mandatory, even if there is clinical improvement with conservative therapy, because cholangitis is most likely to recur with continued obstruction. Emergency invasive therapy is reserved for patients who fail to show a clinical response to antibacterial therapy within the first 36 to 48 hours or for those who deteriorate after an initial clinical improvement. Immediate surgery is indicated for gangrenous cholecystitis and perforation with peritonitis. Long-term administration of antibacterials is required for recurrent cholangitis, as seen in bile duct-bowel anastomosis. Oral cotrimoxazole (trimethoprim/sulfamethoxazole) is the preferred agent. Wound infection rates after biliary tract surgery can be significantly reduced by preoperative administration of prophylactic antibacterials. Newer generation beta-lactams have not proven to be of greater benefit than older agents such as cefuroxime or cefazolin. Antibacterial prophylaxis before endoscopic retrograde cholangiopancreatography (ERCP) should be reserved for patients with obstructive jaundice, since the risk of infectious complications seems to be strongly associated with this clinical condition. Failure to achieve full biliary drainage is the most important factor in predicting septicaemia, and prophylaxis should be prolonged until the bile duct is unobstructed. Piperacillin, cefazolin, cefuroxime, cefotaxime and ciprofloxacin are effective for this indication.

Hepatic cyst infection in autosomal dominant polycystic kidney disease

To characterize the syndrome of hepatic cyst infection in autosomal dominant polycystic kidney disease (ADPKD) and to review its diagnosis and management, we retrospectively studied five such cases in patients from our institution and nine detailed case reports from the literature. The clinical manifestations were an acute (58%) or subacute (42%) febrile illness, typically associated with tenderness in the right upper quadrant, leukocytosis, a very high erythrocyte sedimentation rate, but minor abnormalities of liver function tests. Bacteremia was present in 7 of 11 patients. Enterobacteriaceae grew in pure culture from the cyst fluid in 9 of 12 patients. Complex cysts were observed by ultrasonography (in four of eight patients), computed tomography (in six of nine), and magnetic resonance imaging (in two of two). 111In leukocyte scans were positive in all four patients in whom they were done, and 67Ga scans were positive in only one of three patients. An unfavorable outcome was observed in six of seven patients treated with only antibiotics, in contrast with one of seven patients who received antibiotics and early drainage. In two patients, ciprofloxacin cyst levels were 2.3 and 4.8 times higher than the level in serum; in a third patient, cyst levels remained in therapeutic range 30 hours after the last dose of ciprofloxacin, at which time serum levels were undetectable. Clinical and laboratory features and the use of modern scanning techniques facilitate a prompt diagnosis of infection in hepatic cysts in ADPKD. The treatment of choice is a combination of percutaneous drainage and antimicrobial therapy.

Trimethoprim: mechanisms of action, antimicrobial activity, bacterial resistance, pharmacokinetics, adverse reactions, and therapeutic indications

Trimethoprim has recently been marketed as a single-entity product for the treatment of initial episodes of uncomplicated symptomatic urinary tract infections; it was previously available only in combination with sulfamethoxazole. Trimethoprim exerts antimicrobial activity by blocking the reduction of dihydrofolate to tetrahydrofolate, the active form of folic acid, by susceptible organisms. It has inhibitory activity for most gram-positive aerobic cocci and some gram-negative aerobic bacilli. Resistance to trimethoprim may be either intrinsic or acquired. Acquired resistance most commonly stems from a chromosomal mutation that results in the production of a dihydrofolate reductase enzyme which is less vulnerable to trimethoprim inhibition. Gastrointestinal intolerance and skin eruptions are the most common untoward reactions resulting from the administration of trimethoprim. Trimethoprim constitutes very effective therapy for women with acute symptomatic urinary tract infections caused by E. coli, and the compound compares favorably with alternative standard agents, such as ampicillin and cephalexin. The safety of trimethoprim in the pregnant woman has not been established. Since indiscriminate use of trimethoprim could foster the emergence of trimethoprim resistance, thereby negating the value of both trimethoprim and trimethoprim-sulfamethoxazole, trimethoprim should only be prescribed for well defined indications. Trimethoprim is currently being investigated as definitive therapy for a wide range of infections, including bacterial exacerbations of chronic bronchitis, bacterial pneumonia, and typhoid fever. Initial reports are encouraging.