Emergence of trimethoprim-resistant enterobacteria in patients receiving long-term co-trimoxazole for the control of intractable urinary-tract infection

Risk factors for hospital acquisition of trimethoprim-sulfamethoxazole resistant Stenotrophomonas maltophilia in adults: A matched case-control study

BACKGROUND/PURPOSE

The emergence of trimethoprim-sulfamethoxazole resistant Stenotrophomonas maltophilia (TSRSM) represents a serious threat to patients. The aim of current study was to identify risk factors associated with hospital-acquired TSRSM occurrence in adult inpatients.

METHODS

We conducted a matched case-control study in Tri-Service General Hospital, Taipei, Taiwan. From January 2014 through June 2015, case patients with TSRSM and control patients with trimethoprim-sulfamethoxazole susceptible S. maltophilia (TSSSM) during hospitalization were identified. Control patients were matched with TSRSM cases for age (within five years), sex, and site of isolation at a ratio of 1:1.

RESULTS

A total of 266 patients were included in our study (133 cases and 133 matched controls). Bivariable analysis showed that previous exposure to fluoroquinolone [odds ratio (OR), 2.693; 95% confidence interval (CI, 1.492-5.884; p = 0.002)], length of intensive care unit stay (OR, 1.015 per day; 95% CI, 1.001-1.030; p = 0.041), and length of hospital stay (OR, 1.012 per day; 95% CI, 1.002-1.023; p = 0.018) prior to S. maltophilia isolation were associated with TSRSM occurrence. A multivariable analysis showed that previous exposure to fluoroquinolone (OR, 3.158; 95% CI, 1.551-6.430; p = 0.002) was an independent risk factor for TSRSM occurrence after adjustment.

CONCLUSION

Previous fluoroquinolone use was an independent risk factor for hospital-acquired TSRSM occurrence in adult inpatients, suggesting that judicious administration of fluoroquinolone may be important for limiting TSRSM occurrence.

Prophylactic use of antimicrobials in commonly performed outpatient urologic procedures

An antimicrobial is an agent capable of killing or inhibiting the growth of a micro-organism. Antimicrobial prophylaxis encompasses efforts to prevent postprocedure infections through the use of an antimicrobial agent before, and, in some cases, for a limited time after a procedure. A thorough history and physical examination are essential to identify host factors that increase a patient's risk for postprocedural infection. Risk-modifying factors include age, anatomy, geographical area of residence, immune and nutritional status, cardiac valve integrity, prosthetic joints, the presence of indwelling hardware and distant infectious wounds. Prophylaxis for the most common urologic outpatient procedures can be attained with oral trimethoprim-sulfamethoxazole or fluoroquinolone administered between 2 h and 30 min before a procedure. Special consideration for the type and duration of prophylaxis should be given to patients with moderate to severe cardiac valvular conditions and recently inserted prosthetic joints.

Acute lymphoblastic leukaemia: trimethoprim resistant organisms during treatment

A cross sectional study was carried out in children receiving treatment for acute lymphoblastic leukaemia to determine the prevalence of trimethoprim resistant organisms in their gut flora and to compare this with a control population. There was a significantly higher prevalence of trimethoprim resistant bacteria in the study group (61%) compared with controls (14%). A longitudinal study showed that emergence of these organisms was intermittent during treatment.

Prevention of urinary tract infections

Potential candidates for measures designed to prevent urinary tract infections include (1) women (or girls) with frequent exogenous reinfections; (2) pregnant women; (3) hospitalized patients with short-term indwelling catheters; (4) men with chronic bacterial prostatitis; (5) patients with neurogenic bladders being managed with either intermittent catheterization or chronic indwelling catheters; and (6) men undergoing urologic surgery. Patients in the first three categories represent the vast majority of men and women with preventable urinary tract infections. On the basis of our current understanding of the pathogenesis of urinary infections in women, potential preventive measures can be envisioned. To date, the most successful methods in susceptible women include continuous low-dose antimicrobial prophylaxis or postintercourse antibiotic prophylaxis. In controlled clinical trials, the efficacy of low-dose trimethoprim-sulfamethoxazole, trimethoprim, or nitrofurantoin has repeatedly been demonstrated, and the cost effectiveness of this approach has also been established. An alternative strategy, intermittent, self-administered, single-dose antimicrobial therapy, may be useful in selected circumstances. Screening of high-risk patients for asymptomatic infections has largely been abandoned except in pregnant women in whom this practice remains an important preventive measure. Exciting newer approaches to prevention based on studies clarifying the fimbrial structures mediating bacterial adherence to receptors on uroepithelial cells include the use of receptor analogs and immunoprophylaxis, but these approaches are not yet of demonstrated clinical efficacy.

Oral antibiotic prophylaxis in patients with cancer: a double-blind randomized placebo-controlled trial

In an attempt to reduce the incidence of fever and infection, we randomized patients with cancer to receive trimethoprim/sulfamethoxazole plus erythromycin (TMP/SMX + E) versus placebos after each cycle of chemotherapy (no crossover) and to continue until granulocytopenia (polymorphonuclear leukocytes less than 500/mm3) resolved or the patient became febrile. We evaluated 541 episodes (150 patients); 249 episodes (77 patients) with TMP/SMX + E and 292 episodes (73 patients) with placebos. The patients' median age was 17 years. Thirty percent of the patients had leukemia, 23% had lymphoma, and 47% had solid tumors. Compliance with prescribed medication was prospectively rated as excellent in 60.6%, good in 11.7%, poor in 11.1%, and unknown in 16.6%; compliance was better for the placebo group (P = 0.001). The overall incidence of fever or infection was 22.1% for the TMP/SMX + E group versus 26.9% for the placebo group. When only episodes with excellent compliance in which granulocytopenia was documented were compared, the incidence of fever or infection was 18.1% for the TMP/SMX + E group vs 32.2% for the placebo group (P = 0.009), with bacterial infection occurring in 3.8% of the TMP/SMX + E group vs 11.9% of the placebo group (P = 0.019), and unexplained fever in 10.5% of the TMP/SMX + E group vs 19.6% of the placebo group (P = 0.037). Patients with good or poor compliance showed no significant benefit from the TMP/SMX + E, and patients with excellent compliance did best, regardless of whether they were receiving antibiotics or placebos, suggesting that patient compliance is an important independent variable. The incidence of fever or infection was significantly lower for patients with leukemia with excellent compliance who received antibiotics (P = 0.037) than for patients with lymphomas or solid tumors. Oral antibiotic prophylaxis reduced the incidence of fever and infection in some granulocytopenic patients, but the benefit was limited and restricted to patients whose compliance was complete.

Emergence of high-level trimethoprim resistance in fecal Escherichia coli during oral administration of trimethoprim or trimethoprim--sulfamethoxazole

The effect of daily administration of trimethoprim (TMP), trimethoprim--sulfamethoxazole (TMP--SMX), or placebo on aerobically grown fecal gram-negative bacteria was monitored in 136 students from the United States during a two-week diarrhea-prevention study in Mexico. Unlike patients in other studies with these agents, who had urinary-tract infection or granulocytopenia, most persons in this study had no change in total fecal Enterobacteriaceae and had high-level TMP and SMX resistance in virtually all these strains. Escherichia coli was the predominant TMP-resistant organism isolated; 96 per cent of 165 TMP-resistant Esch. coli isolates were resistant to at least four antimicrobial agents, and 25 per cent were resistant to seven. TMP resistance was transferable in 40 ot 100 strains tested. Despite the lack of TMP resistance in other studies of prophylaxis, our results clearly demonstrate the remarkable capacity for emergence and dissemination of resistance to this agent.

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.