Trimethoprim-sulfamethoxazole

Resistance Gene Association and Inference Network (ReGAIN): A Bioinformatics Pipeline for Assessing Probabilistic Co-Occurrence Between Resistance Genes in Bacterial Pathogens

The rampant rise of multidrug resistant (MDR) bacterial pathogens poses a severe health threat, necessitating innovative tools to unravel the complex genetic underpinnings of antimicrobial resistance. Despite significant strides in developing genomic tools for detecting resistance genes, a gap remains in analyzing organism-specific patterns of resistance gene co-occurrence. Addressing this deficiency, we developed the Resistance Gene Association and Inference Network (ReGAIN), a novel web-based and command line genomic platform that uses Bayesian network structure learning to identify and map resistance gene networks in bacterial pathogens. ReGAIN not only detects resistance genes using well-established methods, but also elucidates their complex interplay, critical for understanding MDR phenotypes. Focusing on ESKAPE pathogens, ReGAIN yielded a queryable database for investigating resistance gene co-occurrence, enriching resistome analyses, and providing new insights into the dynamics of antimicrobial resistance. Furthermore, the versatility of ReGAIN extends beyond antibiotic resistance genes to include assessment of co-occurrence patterns among heavy metal resistance and virulence determinants, providing a comprehensive overview of key gene relationships impacting both disease progression and treatment outcomes.

Overview of Antibiotic-Induced Nephrotoxicity

Drug-induced nephrotoxicity accounts for up to 60% of cases of acute kidney injury (AKI) in hospitalized patients and is associated with increased morbidity and mortality in both adults and children. Antibiotics are one of the most common causes of drug-induced nephrotoxicity. Mechanisms of antibiotic-induced nephrotoxicity include glomerular injury, tubular injury or dysfunction, distal tubular obstruction from casts, and acute interstitial nephritis (AIN) mediated by a type IV (delayed-type) hypersensitivity response. Clinical manifestations of antibiotic-induced nephrotoxicity include acute tubular necrosis (ATN), AIN, and Fanconi syndrome. Given the potential nephrotoxic effects of antibiotics on critically ill patients, the use of novel biomarkers can provide information to optimize dosing and duration of treatment and can help prevent nephrotoxicity when traditional markers, such as creatinine, are unreliable. Use of novel kidney specific biomarkers, such as cystatin C and urinary kidney injury molecule-1 (KIM-1), may result in earlier detection of AKI, dose adjustment, or discontinuation of antibiotic and development of nonnephrotoxic antibiotics.

Clinical features, risk factors, diagnosis, and treatment of trimethoprim-sulfamethoxazole-induced hypoglycemia

OBJECTIVE

Hypoglycemia is a sporadic and serious adverse reaction of trimethoprim-sulfamethoxazole (TMP-SMX) due to its sulfonylurea-like effect. This study explored the clinical characteristics, risk factors, treatment, and prognosis of TMP-SMX-induced hypoglycemia.

METHODS

Case reports and series of TMP-SMX-induced hypoglycemia were systematically searched using Chinese and English databases. Primary patient and clinical information were extracted for analysis.

RESULTS

A total of 34 patients were reported from 31 studies (16 males and 18 females). The patients had a median age of 64 years (range 0.4-91), and 75.8% had renal dysfunction. The median duration of a hypoglycemic episode was six days (range 1-20), and the median minimum glucose was 28.8 mg/dL (range 12-60). Thirty-two patients (97.0%) showed neuroglycopenic symptoms, with consciousness disturbance (30.3%) and seizure (24.2%), sweating (18.2%), confusion (15.2%), asthenia (12.1%) being the most common symptoms. Fifteen patients (44.1%) had elevated serum insulin levels, with a median of 31.8 μU/mL (range 3-115.3). C-peptide increased in 13 patients (38.2%), with a median of 7.7 ng/mL (range 2.2-20). Complete recovery from symptoms occurred in 88.2% of patients without sequelae. The duration of hypoglycemia symptoms was 8 hours to 47 days after the intervention. Interventions included discontinuation of TMP-SMX, intravenous glucose, glucagon, and octreotide.

CONCLUSION

Hypoglycemia is a rare and serious adverse effect of TMP-SMX. Physicians should be aware of this potential adverse effect, especially in patients with renal insufficiency, increased drug doses, and malnutrition.

Multipurpose Drugs Active Against Both Plasmodium spp. and Microorganisms: Potential Application for New Drug Development

Malaria, a disease caused by the protozoan parasites Plasmodium spp., is still causing serious problems in endemic regions in the world. Although the WHO recommends artemisinin combination therapies for the treatment of malaria patients, the emergence of artemisinin-resistant parasites has become a serious issue and underscores the need for the development of new antimalarial drugs. On the other hand, new and re-emergences of infectious diseases, such as the influenza pandemic, Ebola virus disease, and COVID-19, are urging the world to develop effective chemotherapeutic agents against the causative viruses, which are not achieved to the desired level yet. In this review article, we describe existing drugs which are active against both Plasmodium spp. and microorganisms including viruses, bacteria, and fungi. We also focus on the current knowledge about the mechanism of actions of these drugs. Our major aims of this article are to describe examples of drugs that kill both Plasmodium parasites and other microbes and to provide valuable information to help find new ideas for developing novel drugs, rather than merely augmenting already existing drug repurposing efforts.

Sulfamethoxazole-induced sulfamethoxazole urolithiasis: a case report

BACKGROUND

Drug-induced urolithiasis falls into two categories: drug-induced and metabolically-induced. Certain antimicrobials are associated with each; sulfonamides are associated with drug- or metabolite-containing calculi when taken in large doses over a long period of time. Trimethoprim-sulfamethoxazole, a member of the sulfonamide family, is a rare cause of drug-induced calculi. Cases of sulfonamide urolithiasis occurring in patients with known stone disease have rarely been reported.

CASE PRESENTATION

We report a case of a patient with a brief history of recurrent calcium oxalate nephrolithiasis requiring 2 ureteroscopic procedures whose existing 6 mm lower pole renal stone more than quadrupled in size to form a 4 cm renal staghorn after 4 months of high-dose treatment for Nocardia pneumonia with trimethoprim-sulfamethoxazole. After ureteroscopy with laser lithotripsy and basketing of fragments, the stone was found to be predominantly composed of N4-acetyl-sulfamethoxazole, a metabolite of sulfamethoxazole.

CONCLUSION

Stones composed of sulfamethoxazole or its metabolites are rare but have known associated risk factors that should be considered when prescribing this antibiotic. This case report illustrates additional risk factors for consideration, including pre-existing urinary calculi that may serve as a nidus for sulfamethoxazole deposition, and reviews treatment and prevention methods.

Challenges to Early Discharge of Patients with Upper Urinary Tract Infections by ESBL Producers: TMP/SMX as a Step-Down Therapy for Shorter Hospitalization and Lower Costs

Background

Urinary tract infections (UTIs) caused by extended spectrum beta-lactamase (ESBL) producing pathogens have increased and are treated with carbapenem in general. Carbapenem use is associated with prolonged hospitalization or daily outpatient visit. The aim of this study was to investigate patients with UTIs by ESBL-producing pathogens for early discharge using an old oral antibiotic, trimethoprim-sulfamethoxazole (TMP-SMX), which is susceptible to ESBL-producing pathogens.

Methods

Data on UTIs caused by ESBL-producing pathogens from a single tertiary hospital were collected retrospectively. Patients who had been treated with intravenous carbapenems or oral TMP/SMX were included. Patients’ clinical and microbiological outcomes were compared between oral TMP/SMX and ertapenem treatment groups.

Results

A total of 103 patients were included, 21 of whom had been treated with TMP/SMX, whereas 82 with ertapenem. Clinical outcomes between the two groups were not significantly different (TMP/SMX: 90.5%; ertapenem: 84.1%, p = 0.73). The microbiological cure rate was higher in the TMP/SMX group than in the ertapenem group (90.5% vs 58.5%, respectively, p = 0.01). The mean duration of hospitalization was significantly shorter in the TMP/SMX group than in the ertapenem group (8.00 ± 10.50 days vs 14.00 ± 37.00 days, p = 0.07). The mean duration of antibiotic treatment was longer in the ertapenem group than in the TMP/SMX group (16.45 ± 4.77 vs 12.76 ± 5.37 days, p = 0.006).

Conclusion

For susceptible pathogens, TMP/SMX may enable early discharge as an effective oral antibiotic treatment option for UTIs caused by ESBL-positive pathogens. Additionally, use of oral antibiotics can shorten hospital stays and reduce medical costs.

Silver-coated magnetic nanoparticles as an efficient delivery system for the antibiotics trimethoprim and sulfamethoxazole against E. Coli and S. aureus: release kinetics and antimicrobial activity

Trimethoprim and sulfamethoxazole are prescribed for a broad spectrum of bacteria. However, the use of these medicines is restricted due to the risk of microbial resistance in the body. Nanotechnology is a strategy for overcoming this problem by helping develop novel drug delivery systems. This study aims to assess the ability of Fe₃O₄/Ag and Fe₃O₄@SiO₂/Ag nanoparticles to improve efficiency of the traditional formulation of trimethoprim and sulfamethoxazole. Fe₃O₄/Ag and Fe₃O₄@SiO₂/Ag were found to have sphere-like morphologies with average sizes of 33.2 and 35.1 nm, respectively. The values of the zeta potential for the pure sulfamethoxazole and trimethoprim were -30.6 and -10.0 mV, respectively, which increased to zero or even larger positive values after being conjugated with the NPs. The study of the release kinetics showed that 64.7% of the medicines were released from the carriers within 40 days. The values of MIC for sulfamethoxazole, trimethoprim, Fe₃O₄/Ag/sulfamethoxazole, Fe₃O₄/Ag/trimethoprim, Fe₃O₄@SiO₂/Ag/sulfamethoxazole, and Fe₃O₄@SiO₂/Ag/trimethoprim against Escherichia coli were calculated to be 12, 9, 4, 4, 4, and 4 μg/mL, respectively. Besides, the relevant values against Staphylococcus aureus were measured to be 12, 9, 4, 4, 3, and 2 μg/mL, respectively. The use of synthesized nanomaterials for the delivery of these antibiotics leads to smaller doses compared to their traditional forms.

Quantification of Serum Sulfamethoxazole and Trimethoprim by Ultra-fast Solid-Phase Extraction-Tandem Mass Spectrometry

BACKGROUND

The combination of trimethoprim (TMP) and sulfamethoxazole (SMX) is used to treat a number of bacterial infections. TMP/SMX concentrations in serum are conventionally monitored using high-performance liquid chromatography (HPLC) or liquid chromatography tandem mass spectrometry. These methods require laborious manual extraction techniques and relatively long sample analysis times, necessitating the development of a simple, high-throughput method. A simple, high-throughput method to measure TMP/SMX using ultra-fast solid-phase extraction (SPE)-tandem mass spectrometry has been developed.

METHODS

Calibration standards, quality control materials, and patient samples were precipitated with acetonitrile containing isotopically labeled internal standards. Samples were vortexed, centrifuged for 5 minutes at 2053g, and the resulting supernatant was diluted in aqueous mobile phase and injected onto the C18 SPE cartridge. MS/MS analysis was performed by electrospray ionization in positive ion mode at a rate of <20 seconds per sample. A 5-point linear 1/x calibration curve was used to calculate sample concentrations.

RESULTS

The intra-assay precision coefficients of variation were <6% and <7% for SMX and TMP, respectively, and <10% for both interassay precision coefficients of variation. Comparison studies using 50 patient and spiked serum samples showed r values of 0.9890 and 0.9853 and y-intercept values of -1.918 and -1.357, respectively compared with the HPLC reference method. All data points were <±15% of the mean. Linearity [r = 0.9952 (SMX) and 0.9954 (TMP)] was established from 12 to 400 mcg/mL with a detection limit of 0.47 mcg/mL, and 1.2-40 mcg/mL with a detection limit of 0.06 mcg/mL, for SMX and TMP, respectively. For either drug, no significant carryover was observed after samples at the upper limit of quantification. No interference was observed from any of the 77 drugs and respective metabolites tested.

CONCLUSIONS

A high-throughput SPE-tandem mass spectrometry method for TMP/SMX quantification was developed. The <20 seconds analysis time is a significant improvement compared with traditional HPLC and liquid chromatography tandem mass spectrometry methods, without sacrificing analytical performance.

Risk factors associated with increased discontinuation rate of trimethoprim-sulfamethoxazole used as a primary prophylaxis for Pneumocystis pneumonia: A retrospective cohort study

BACKGROUND

The use of trimethoprim-sulfamethoxazole (TMP-SMX) for Pneumocystis pneumonia (PcP) prophylaxis is often discontinued owing to adverse drug reactions. Half-dosage of TMP-SMX (40/200 mg daily) is considered more tolerable than the conventional dosage (80/400 mg daily). However, patient background characteristics that are associated with the discontinuation of TMP-SMX prophylaxis and suitable for reduced dosage remain unclear. In this study, we aimed to identify the risk factors for the discontinuation of and efficacy of different doses of TMP-SMX prophylaxis in patients with creatinine clearance higher than 30 mL/min.

METHODS

We retrospectively evaluated 318 immunocompromised non-human immunodeficiency virus (HIV)-infected patients (194 men and 124 women; median age, 68.5 [interquartile range, 59-75] years) who underwent TMP-SMX therapy as a primary PcP prophylaxis between July 2014 and August 2019. The patients were segregated into two groups on the basis of dosage: single-strength (SS; n = 244) and half-strength (HS; n = 74) groups. We evaluated PcP occurrence, TMP-SMX discontinuation rate, and discontinuation-related risk factors in these groups.

RESULTS

PcP did not occur in either group. The univariate and multivariate Cox proportional hazards models revealed that the SS dosage and renal function (e.g. serum creatinine and creatinine clearance) were independently associated with prophylaxis discontinuation. At 24 weeks, the HS group presented significantly lower discontinuation rates than the SS group (P = 0.019, log-rank test). In the SS group, patients with mild renal impairment (e.g. serum creatinine ≥0.78 mg/dL or creatinine clearance ≤64.26 mL/min) presented significantly higher TMP-SMX discontinuation rates than those without such an impairment (P < 0.05, log-rank test with Bonferroni correction). This difference was not significant in the HS group.

CONCLUSION

Mild renal impairment might increase the risk of discontinuation of conventional TMP-SMX prophylaxis. In patients with a mild renal impairment, the HS dosage may improve tolerability while maintaining prophylactic efficacy.

Dose-Dependent Hyperkalemia Among Hospitalized, HIV-Infected Patients Receiving Sulfamethoxazole/Trimethoprim

Background: Sulfamethoxazole-trimethoprim (SXT) therapy is commonly used in HIV-infected patients and is associated with hyperkalemia and elevated serum creatinine (SCr). Objective: The purpose of this study was to examine the frequency of hyperkalemia and elevated SCr in hospitalized, HIV-infected patients receiving SXT. Methods: This was a retrospective, single-center cohort study. HIV-infected hospitalized patients receiving a minimum of 3 consecutive days of SXT were included. Patients were grouped according to high dose (≥10 mg/kg/d) and low dose (<10 mg/kg/d) trimethoprim. The primary end point was the frequency of hyperkalemia, severe hyperkalemia, and elevated SCr. Secondary end points included an evaluation of concomitant potassium-altering medications and concomitant nephrotoxic drugs. Results: A total of 100 consecutive patients were selected from all possible patients who met inclusion criteria. Overall, 47 patients experienced at least 1 adverse drug event (ADE) of either hyperkalemia or increased SCr, with 20 patients experiencing these ADEs in the low-dose group and 27 patients experiencing these ADEs in the high-dose group (P = 0.229). The ADEs of hyperkalemia or increased SCr occurred after a shorter period (5.5 vs 8.7 days) in the high-dose group (P = 0.049). Overall frequency of elevated SCr was 24% and of elevated serum K was 36%. Hyperkalemia requiring a therapeutic intervention occurred in 12 patients in the high-dose group compared with 2 in the low-dose group (P = 0.009). Conclusion and Relevance: Rates of elevated SCr and hyperkalemia in hospitalized HIV-infected patients receiving SXT are significant. Hyperkalemia requiring intervention is more common in patients receiving high-dose SXT.

Assessment of trimethoprim-sulfamethoxazole susceptibility testing methods for fastidious Haemophilus spp

OBJECTIVES

To compare the determinants of trimethoprim-sulfamethoxazole resistance with established susceptibility values for fastidious Haemophilus spp., to provide recommendations for optimal trimethoprim-sulfamethoxazole measurement.

METHODS

We collected 50 strains each of Haemophilus influenzae and Haemophilus parainfluenzae at Bellvitge University Hospital. Trimethoprim-sulfamethoxazole susceptibility was tested by microdilution, E-test and disc diffusion using both Mueller-Hinton fastidious (MH-F) medium and Haemophilus test medium (HTM) following EUCAST and CLSI criteria, respectively. Mutations in folA, folP and additional determinants of resistance were identified in whole-genome-sequenced isolates.

RESULTS

Strains presented generally higher rates of trimethoprim-sulfamethoxazole resistance when grown on HTM than on MH-F, independent of the methodology used (average MIC 2.6-fold higher in H. influenzae and 1.2-fold higher in H. parainfluenzae). The main resistance-related determinants were as follows: I95L and F154S/V in folA; 3- and 15-bp insertions and substitutions in folP; acquisition of sul genes; and FolA overproduction potentially linked to mutations in -35 and -10 promoter motifs. Of note, 2 of 19 H. influenzae strains (10.5%) and 9 of 33 H. parainfluenzae strains (27.3%) with mutations and assigned as resistant by microdilution were inaccurately considered susceptible by disc diffusion. This misinterpretation was resolved by raising the clinical resistance breakpoint of the EUCAST guidelines to ≤30 mm.

CONCLUSIONS

Given the routine use of disc diffusion, a significant number of strains could potentially be miscategorized as susceptible to trimethoprim-sulfamethoxazole despite having resistance-related mutations. A simple modification to the current clinical resistance breakpoint given by the EUCAST guideline for MH-F ensures correct interpretation and correlation with the reference standard method of microdilution.

Pharmacological properties of oral antibiotics for the treatment of uncomplicated urinary tract infections

The therapeutic management of uncomplicated bacterial urinary tract infections (UTIs) is based on short-term courses of oral antibiotics. The preferred drugs are nitrofurantoin trimethoprim-sulfamethoxazole, fosfomycin trometamol, fluoroquinolones and β-lactam agents. The choice of agent for treating uncomplicated UTIs should be based on the pharmacokinetic characteristics of the molecule so that clinical benefit is optimized and the risk of antibacterial resistance is minimized. This article discusses the general pharmacokinetic-pharmacodynamic (PK/PD) aspects of antimicrobial chemotherapy, the PK/PD characteristics of oral antimicrobial agents for the treatment of uncomplicated UTIs and the pharmacological and therapeutic strategies for limiting or preventing bacterial resistance.

Cefepime shows good efficacy and no antibiotic resistance in pneumonia caused by Serratia marcescens and Proteus mirabilis - an observational study

Background

Many antibiotics have no effect on Gram-positive and Gram-negative microbes, which necessitates the prescription of broad-spectrum antimicrobial agents that can lead to increased risk of antibiotic resistance. These pathogens constitute a further threat because they are also resistant to numerous beta-lactam antibiotics, as well as other antibiotic groups. This study retrospectively investigates antimicrobial resistance in hospitalized patients suffering from pneumonia triggered by Gram-negative Serratia marcescens or Proteus mirabilis.

Methods

The demographic and clinical data analyzed in this study were obtained from the clinical databank of the HELIOS Clinic, Witten/Herdecke University, Wuppertal, Germany, for inpatients presenting with pneumonia triggered by S. marcescens or P. mirabilis from 2004 to 2014. An antibiogram was conducted for the antibiotics utilized as part of the management of patients with pneumonia triggered by these two pathogens.

Results

Pneumonia was caused by Gram-negative bacteria in 115 patients during the study period from January 1, 2004, to August 12, 2014. Of these, 43 (37.4 %) hospitalized patients [26 males (60.5 %, 95 % CI 45.9 %–75.1 %) and 17 females (39.5 %, 95 % CI 24.9 %–54.1 %)] with mean age of 66.2 ± 13.4 years had pneumonia triggered by S. marcescens, while 20 (17.4 %) patients [14 males (70 %, 95 % CI 49.9 %–90.1 %) and 6 females (30 %, 95 % CI 9.9 %–50.1 %)] with a mean age of 64.6 ± 12.8 years had pneumonia caused by P. mirabilis. S. marcescens showed an increased antibiotic resistance to ampicillin (100 %), ampicillin-sulbactam (100 %), and cefuroxime (100 %). P. mirabilis had a high resistance to tetracycline (100 %) and ampicillin (55 %). S. marcescens (P < 0.0001) and P. mirabilis (P = 0.0003) demonstrated no resistance to cefepime in these patients with pneumonia.

Conclusions

S. marcescens and P. mirabilis were resistant to several commonly used antimicrobial agents, but showed no resistance to cefepime.

Disseminated nocardiosis during systemic steroid therapy for the prevention of esophageal stricture after endoscopic submucosal dissection

An 85-year-old man underwent endoscopic submucosal dissection for a large superficial esophageal epithelial neoplasm, which required removal of 95% of the circumference of the esophageal mucosa. Steroids were given orally to prevent esophageal stricture starting on day 3 postoperatively. In the 6th week of steroid treatment, he developed high fever without other symptoms. Chest computed tomography revealed a nodular lesion in the lung. Sputum sample showed Gram-positive, branching, filamentous bacteria, and a diagnosis of nocardiosis was suspected. Brain magnetic resonance imaging revealed multiple focal lesions which indicated dissemination of nocardiosis. Trimethoprim-sulfamethoxazole was immediately started, which led to the disappearance of pulmonary and cerebral nocardiosis with alleviation of fever. Recently, oral steroid treatment has been widely used for the prevention of esophageal stricture. However, the present case indicates the risk of life-threatening infection and the importance of close monitoring of this treatment.

The efficacy and safety of amoxicillin, trimethoprim-sulfamethoxazole, and spironolactone for treatment-resistant acne vulgaris

In situations where acne has proved resistant to other systemic agents or they are not indicated and isotretinoin is not desired by patients, the authors find amoxicillin, TMP-SMX, and spironolactone, alone or in combination, useful alternatives. In women who have acne, spironolactone can be used, and in patients who have sulfa allergy, amoxicillin can be used. It is important to continue alternate topical therapy along with these interventions to augment the improvement and to assist in the eventual discontinuance of oral medication. All of the authors' patients were using topical therapy concomitantly and, although this may have contributed to improvement, the authors believe the addition of amoxicillin, TMP-SMX, or spironolactone contributes to the majority of improvement. Tetrospective chart analysis provides supportive data for amoxicillin, TMP-SMX, and spironolactone in the treatment of refractory acne vulgaris.

Current use of anti-infectives in dermatology

Dermatologic diseases encompass a broad category of pathologic situations. Infection remains a significant aspect of the pathology faced in patient encounters, and it is natural to expect that anti-infectives play a major element in the armamentarium utilized by dermatologists. Aside from the treatment of the classic bacterial and fungal infections, there are now new uses for antiviral agents to help suppress recurrent disease, such as herpes simplex. There is also the novel approach of using anti-infectives, or agents that have been thought to have antimicrobial activity, to treat inflammatory diseases. This review describes anti-infectives, beginning with common antibiotics used to treat bacterial infections. The discussion will then cover the current use of antivirals. Finally, the description of antifungals will be separated, starting with the oral agents and ending with the topical antimycotics. The use of anti-infectives in tropical dermatology has been purposefully left out, and perhaps should be the subject of a separate review. Cutaneous bacterial infections consist chiefly of those microorganisms that colonize the skin, such as species of staphylococcus and streptococcus. Propionibacterium acnes and certain other anaerobes can be involved in folliculitis, pyodermas and in chronic conditions such as hidradenitis suppurativa.

Successful orthotopic liver transplantation after trimethoprim-sulfamethoxazole associated fulminant liver failure

Trimethoprim-sulfamethoxazole (TMP-SMZ) is one of the most commonly used antibiotics. Although many of its adverse effects are well recognized, TMP-SMZ related hepatotoxicity is considered rare and is usually characterized by cholestasis or mixed hepatocellular-holestatic reactions. In this study, we describe the case of a previously healthy young man with acute fulminant liver failure caused by TMP-SMZ. The patient presented with complaints of 'flu-like' symptoms with myalgia and fever after taking TMP-SMZ for 7 d for otitis externa. The patient subsequently developed fever, worsening jaundice, and a rash on his neck and chest. Liver enzymes peaked on day 3 with alanine aminotransferase (ALT) 11,549, aspartate aminotransferase (AST) 23,289, alkaline phosphatase 245, and total bilirubin 10.3 mg/dL, with a conjugated bilirubin of 8.3 mg/dL, prothrombin time (PT) 60.5 s, partial normalized ratio (PTT) 49 s, and international normalized ratio (INR) 7.5. Of note, acetaminophen level on admission was undetectable. Serology for hepatitis A, B, C, cytomegalovirus, HIV, toxoplasmosis, and blood cultures were all negative. The patient developed hepatic encephalopathy with hallucination on day 4. Laboratory tests revealed a serum ammonia level of 190 U, serum creatinine kinase (CK) 10,466 (42 on admission), serum creatinine 8.2 mg/dL (1.2 on admission), and significant metabolic acidosis. Renal ultrasound was unremarkable. The patient was started on hemodialysis for acute renal failure. Meanwhile, liver transplantation assessment was also initiated. On day 8 post-admission (15 d after taking TMP-SMZ), the patient received a successful orthotopic liver transplant.

Severe thrombocytopenia possibly associated with TMP/SMX therapy

OBJECTIVE

To report a case of possible severe, life-threatening thrombocytopenia associated with trimethoprim/sulfamethoxazole (TMP/SMX) therapy.

CASE SUMMARY

A 54-year-old white woman received a 10-day course of TMP/SMX for treatment of chronic sinusitis. One day after finishing the course of TMP/SMX therapy, the presented to the emergency department because of the development of scattered petechiae on both hands and blood blisters in her mouth. On admission, her complete blood cell count results revealed a severely low platelet count of 2 x 10(3)/mm3. Other laboratory test results were normal, except for elevated blood glucose (nonfasting blood glucose). TMP/SMX was believed to be the most likely cause of thrombocytopenia. She was treated successfully with a transfusion of 2 units of platelets and oral prednisone. Her platelet count increased to 110 x 10(3)/mm3 4 days after discontinuation of TMP/SMX. She was discharged on hospital day 5. On follow-up (2 wk after hospital discharge), her platelet count was normal (351 x 10(3)/mm3).

DISCUSSION

TMP/SMX has been implicated as a cause of thrombocytopenia, which is defined as platelet count < 150 x 10(3)/mm3. Although it is uncommon, spontaneous severe bleeding may occur when platelet count decreases to < or = 10 x 10(3)/mm3. Thrombocytopenia associated with TMP/SMX appears to be an immune-mediated process resulting in platelet destruction by drug-dependent platelet antibodies. Treatment of thrombocytopenia associated with TMP/SMX therapy includes discontinuation of the offending drug and the use of corticosteroids. Platelet transfusion and intravenous immunoglobulin may be required in some patients.

CONCLUSIONS

Thrombocytopenia associated with TMP/SMX therapy can be serious or life threatening because it may result in significant bleeding complications. This hematologic adverse effect of TMP/SMX may occur even with the usual recommended dosage and duration of therapy. Careful monitoring of complete blood cell count, including platelet count, before and during TMP/SMX therapy is suggested.

Systemic antibiotic agents

Understanding the breadth of systemic antimicrobial agents available for use by the dermatologist and their associated side-effect profiles and drug interactions allows the clinician to offer patients optimal care in the management of cutaneous infectious disease.

Acute fulminant hepatic failure in a woman treated with phenytoin and trimethoprim-sulfamethoxazole

Massive hepatic necrosis following exposure to phenytoin and trimethoprim-sulfamethoxazole is a rare occurrence and to the best of our knowledge has not been reported previously. Acute hepatic failure following administration of trimethoprim-sulfamethoxazole has rarely been seen, and only 4 cases have been well documented pathologically. We report a case of acute liver failure in a 60-year-old woman following ingestion of phenytoin and trimethoprim-sulfamethoxazole concomitantly over a 9-day period. Autopsy findings revealed acute fulminant hepatic failure. This case demonstrates the effects of chemical-chemical interactions in the potentiation of hepatotoxicity of single agents and specifically illustrates the need for discontinuing trimethoprim-sulfamethoxazole in the presence of early liver injury.

Oral antibiotics: are the old still gold?

Most common infections in ambulatory care can be treated effectively and safely with conventional antibiotics. A rational approach using such antibiotics as primary choices and reserving newer antibiotics for selected, more difficult-to-treat infections will result in substantial cost savings and may help to prevent the rapid development of drug resistance.

Crystal structure of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase, a potential target for the development of novel antimicrobial agents

BACKGROUND

Folate cofactors are essential for life. Mammals derive folates from their diet, whereas most microorganisms must synthesize folates de novo. Enzymes of the folate pathway therefore provide ideal targets for the development of antimicrobial agents. 6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the transfer of pyrophosphate from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in the folate biosynthetic pathway.

RESULTS

The crystal structure of HPPK from Escherichia coli has been determined at 1.5 A resolution with a crystallographic R factor of 0.182. The HPPK molecule has a novel three-layered alpha beta alpha fold that creates a valley approximately 26 A long, 10 A wide and 10 A deep. The active center of HPPK is located in the valley and the substrate-binding sites have been identified with the aid of NMR spectroscopy. The HP-binding site is located at one end of the valley, near Asn55, and is sandwiched between two aromatic sidechains. The ATP-binding site is located at the other end of the valley. The adenine base of ATP is positioned near Leu111 and the ribose and the triphosphate extend across and reach the vicinity of HP.

CONCLUSIONS

The HPPK structure provides a framework to elucidate structure/function relationships of the enzyme and to analyze mechanisms of pyrophosphoryl transfer. Furthermore, this work may prove useful in the structure-based design of new antimicrobial agents.

Evaluation of and antimicrobial therapy for recurrent urinary tract infections in women

The problem with recurrent urinary tract infections in women is enormous and contributes significantly to national health care costs. As the role of office urology and the external "cost-effective" pressures placed on the practicing urologist have heightened, a consistent, logical approach towards diagnosis and management of urinary tract infection becomes essential. This article briefly discusses the cause and pathophysiology behind recurrent urinary tract infections in women. A practical discussion of proper evaluation and treatment options will also be provided in hopes of offering the clinician a simple, stepwise approach to this sometimes difficult condition.

Antimicrobial agents for the dermatologist. II. Macrolides, fluoroquinolones, rifamycins, tetracyclines, trimethoprim-sulfamethoxazole, and clindamycin

This article is the second of a two-part series reviewing antimicrobial agents that are used by the dermatologist. In part I we reviewed beta-lactam antibiotics and related compounds. In this section we again emphasize some newer agents (macrolides, fluoroquinolones) as well as some of the more commonly employed older agents (rifamycins, tetracyclines, trimethoprim-sulfamethoxazole, and clindamycin.

Trimethoprim/sulfamethoxazole-induced hypoglycemia in a patient with acute renal failure

OBJECTIVE

To report a case of trimethoprim/sulfamethoxazole (TMP/SMX)-induced hypoglycemia in a patient with acute renal failure.

DATA SOURCES

English-language references identified via a MEDLINE search from January 1966 to August 1996 and a bibliographic review of pertinent articles.

DATA SYNTHESIS

Similar to sulfonylureas, sulfonamides are thought to cause hypoglycemia by increasing pancreatic secretion of insulin. To date, nine cases of TMP/SMX-induced hypoglycemia have been reported in the literature. This case represents the second report in which a patient experienced TMP/SMX-induced hypoglycemia that resolved after the dosage was adjusted for the patient's decreased renal function. This case involved a 73-year-old comatose white man initiated on high-dose TMP/SMX for nosocomial pneumonia caused by Stenotrophomonas maltophilia. After 5 days of therapy, the patient presented with severe hypoglycemia that persisted over 8 hours despite multiple intravenous bolus doses and infusions of dextrose. The patient had several risk factors that may have compounded his risk for hypoglycemia, including food deprivation and acute renal failure. After management with dextrose and dose adjustment of the patient's TMP/SMX regimen according to renal function, the hypoglycemia resolved.

CONCLUSIONS

TMP/SMX may cause reversible hypoglycemia that may be prolonged (approximately 12 h), particularly in patients with risk factors for hypoglycemia. Common risk factors include compromised renal function, prolonged fasting conditions, malnutrition, and the use of excessive doses. Patients with these risk factors should be monitored closely and, more importantly, initiated on a dosing regimen adjusted for renal impairment.

Whipple disease. Clinical review of 52 cases. The SNFMI Research Group on Whipple Disease. Société Nationale Française de Médecine Interne

Whipple disease is a rare, multiorgan disease with prominent intestinal manifestations. We report a retrospective clinical study of 52 patients recruited in various parts of France from 1967 to 1994. Seventy-three percent of the patients were male. Clinical manifestations preceding the diagnosis were articular for 35 patients (67%), digestive for 8 patients (15%), general for 7 patients (14%), and neurologic for 2 patients (4%). At a later stage of the disease, 44 patients (85%) presented diarrhea, weight loss, and malabsorption, while 8 patients (15%) did not show any gastrointestinal symptom throughout the development of the disease. Forty-three patients (83%) presented arthralgia or arthritis, and 11 (21%) had prominent neurologic symptoms. In addition, cardiovascular symptoms were present in 9 patients (17%); mucocutaneous symptoms, in 9 patients (17%); pleuropulmonary symptoms, in 7 patients (13%); and ophthalmologic symptoms, in 5 patients (10%). All patients but 1 were given a positive diagnosis on histopathologic criteria: jejunal biopsy for 46 patients (90%), lymph node biopsy for 3 patients (6%), brain biopsy for 1 patient (2%), postmortem jejunal and cerebral biopsy for 1 patient (2%). With treatment, the disease evolved favorably in 47 patients (90%), while 5 patients (10%) had unfavorable outcomes (2 deaths from neurologic involvement, 1 patient with chronic dementia, and 2 patients with digestive symptoms insensitive to antimicrobial therapy). Of the 41 patients initially treated successfully and whose treatment has been completed, clinical evolution after discontinuation of treatment was favorable in 34 cases (83%). Clinical relapses occurred in 7 patients. No relapse was observed after treatment by trimethoprim-sulfamethoxazole, alone or following a combination of penicillin and streptomycin, or after the combination of penicillin and streptomycin, whatever the oral follow-up treatment prescribed. The evolution of patients showing a relapse was favorable in all cases after reintroduction of antibiotic therapy. These results are discussed in the light of previously published series and case reports of Whipple disease. The diagnosis of the disease remains difficult at an early phase or when digestive symptoms are absent. It is noteworthy that proximal enteroscopy is sometimes misleading, considered normal on macroscopic examination and nonspecific on pathologic grounds. A normal erythrocyte sedimentation rate represents another pitfall. Histopathology is the key for positive and differential diagnosis, and may require multiple and repeated biopsies. Findings from molecular biology confirm the central role of an uncultured Gram-positive bacillus which was named in 1992 Tropheryma whippelii. A recent report suggests that polymerase chain reaction (PCR) analysis of peripheral blood might allow the diagnosis of Whipple disease in some cases. However, immunologic or cellular parameters such as macrophagic function may play an important, although not clearly elucidated, role in the pathogeny of the disease. Trimethoprim-sulfamethoxazole should be considered the antimicrobial agent of choice in the treatment of Whipple disease, minimizing the risk of cerebral involvement and relapses.

Emerging resistance to antibiotics: impact on respiratory infections in the outpatient setting

OBJECTIVE

To review the major mechanisms of antibiotic resistance and provide an overview of currently available oral antibiotics. This article discusses the impact of antibiotic resistance on respiratory infections (eg, otitis media, sinusitis, and pneumonia) encountered in the outpatient setting and appropriate management strategies for these infections are proposed.

DATA SOURCES

A Medline search was performed to identify recent references from the English language pertinent to this topic. Proposed management schemes for infections due to antibiotic-resistant bacteria were derived from current literature as well as the opinion of the authors.

RESULTS

Currently available oral antibiotics including penicillins, cephalosporins, macrolides, trimethroprim/sulfamethoxazole, and clindamycin continue to provide effective therapeutic options despite the increasing importance of antibiotic resistance in bacteria causing respiratory tract infections in the outpatient setting. The effectiveness of a given agent may no longer be assured, leading to the need for development of updated management strategies for patients experiencing treatment failure with antibiotics. Diagnostic strategies (ie, tympanocentesis) and novel treatment algorithms (eg, use of amoxicillin in combination with amoxicillin/clavulanate) for patients experiencing clinical failures potentially due to antibiotic-resistant bacteria are proposed.

CONCLUSIONS

The increasing prevalence of antibiotic resistant bacteria (especially penicillin-resistant Streptococcus pneumoniae) is leading to new approaches to the management of common respiratory infections in the outpatient setting. Additional experience and careful clinical trials are necessary to identify optimal management strategies for these infections.

Effect of standard-dose trimethoprim/sulfamethoxazole on the serum potassium concentration in elderly men

OBJECTIVE

To determine the effect of standard-dose trimethoprim/sulfamethoxazole (TMP/SMX) (TMP 160 mg and SMX 800 mg q12h) on the serum potassium concentration.

DESIGN

Retrospective and concurrent study.

SETTING

A Veterans Affairs Medical Center.

PATIENTS

Fifty-three men hospitalized at the Fargo Veterans Affairs Medical Center. Thirty-three patients who received standard-dose TMP/SMX for 3 or more days comprised the study group. Twenty patients who received oral cephradine or amoxicillin for 3 or more days comprised the control group. Patients who received potassium supplements, potassium-sparing diuretics, angiotensin-converting enzyme inhibitors, nonsteroidal antiinflammatory drugs, beta-blockers, heparin, known nephrotoxic agents, patients with a serum creatinine concentration of more than 177 mumol/L, and patients with baseline hyperkalemia (serum potassium concentration > 5.1 mmol/L) were excluded.

RESULTS

The serum potassium concentration in the study group was 4.22 +/- 0.40 mmol/L and increased by 0.31 +/- 0.38 mmol/L at the end of therapy (p < 0.001). Twenty-six patients in the study group (78.8%) had an increase in the serum potassium concentration during TMP/SMX therapy. Fourteen of these patients had follow-up serum potassium concentrations obtained after completion of therapy. The serum potassium concentration returned to baseline in 10 of these patients. The serum creatinine concentration also increased during therapy. However, the correlation between the increase in the serum potassium concentration and the increase in the serum creatinine concentration was weak (Pearson r = 0.29). The serum potassium in the control group was 4.34 mmol/L and remained essentially unchanged during therapy.

CONCLUSIONS

Therapy with standard-dose TMP/SMX is associated with a slight increase in the serum potassium concentration. Routine monitoring of the serum potassium concentration in patients who are treated with standard-dose TMP/SMX therapy is unnecessary. However, TMP/SMX should be considered as a possible cause of unexplained hyperkalemia in elderly patients receiving TMP/SMX therapy.

A pharmacokinetic interaction study of didanosine coadministered with trimethoprim and/or sulphamethoxazole in HIV seropositive asymptomatic male patients

1. The pharmacokinetics of didanosine, trimethoprim, and sulphamethoxazole were evaluated in ten HIV seropositive asymptomatic patients as single agents and upon coadministration of single doses. 2. Using a randomized, balanced incomplete block crossover study with at least a 1-week washout period between successive treatments, each patient under fasting conditions received four of the following five treatments: 200 mg didanosine as a single agent; 200 mg trimethoprim + 1000 mg sulphamethoxazole; 200 mg trimethoprim + 200 mg didanosine; 1000 mg sulphamethoxazole + 200 mg of didanosine and; 200 mg trimethoprim + 1000 mg sulphamethoxazole + 200 mg didanosine. 3. Serial blood and urine samples were collected following the administration of each treatment. Plasma and urine samples were analyzed using high-pressure liquid chromatography (h.p.l.c.)/ultraviolet assays specific for unchanged didanosine, trimethoprim and/or sulphamethoxazole. 4. Percent urinary recovery (%UR) and renal clearance (CLR) emerged as consistently affected parameters, being decreased in the case of didanosine (35%, P = 0.016) and trimethoprim (32%, P = 0.019) and increased in the case of sulphamethoxazole (39%, P = 0.079), when all three agents were coadministered. The magnitude of the changes in didanosine CLR and %UR values was no greater when both trimethoprim and sulphamethoxazole were coadministered vs when each single agent was given with didanosine, suggesting that any effect was not additive. 5. Other key parameters such as Cmax, AUC, and t1/2 for didanosine (1309.9 ng ml-1, 1796.9 ng ml-1 h, and 1.61 h, respectively), trimethoprim (1.96 micrograms ml-1, 22.86 micrograms ml-1 h, and 9.03 h, respectively) or sulphamethoxazole (58.62 micrograms ml-1, 799.7 micrograms ml-1 h and 9.84 h, respectively) were not affected when didanosine was coadministered with either trimethoprim (didanosine: 1751.9 ng ml-1, 2158.0 ng ml-1 h, and 1.28 h; trimethoprim: 1.81 micrograms ml-1, 28.89 micrograms ml-1 h, and 11.4 h), sulphamethoxazole (didanosine: 1279.3 ng ml-1, 1793.2 ng ml-1 h, and 1.61 h; sulphamethoxazole: 53.57 micrograms ml-1, 732.1 micrograms ml-1 h, and 8.95 h), or the combination of trimethoprim and sulphamethoxazole (didanosine: 1283.7 ng ml-1, 1941.8 ng ml-1 h, and 1.38 h; trimethoprim: 1.59 micrograms ml-1, 26.68 micrograms ml-1 h, and 11.3 h; sulphamethoxazole: 59.48 micrograms ml-1, 760.9 micrograms ml-1 h, and 9.47 h). 6. Because the observed differences in CLR and %UR are small and not considered to be clinically relevant, it is not necessary to alter the dosing regimens of didanosine, trimethoprim or sulphamethoxazole when administered in combination to HIV seropositive patients.

Combinations of sulphonamides with diaminopyrimidines: how, when and why?

Co-trimoxazole is still widely used for indications where trimethoprim alone is equally effective. The pharmacological rationale of the combination of trimethoprim and sulphamethoxazole involves synergistic action of the two drugs. This is true only from a laboratory point of view; several considerations have led to the conclusion that the synergism between the two components is of only in vivo marginal importance in determining the clinical efficacy of co-trimoxazole. This is due to a greater tissue affinity of trimethoprim compared to that of sulphamethoxazole and, therefore, to the different tissue concentration ratios obtained in vitro and in vivo. Another claim sustaining the combination is the prevention of developing resistance to trimethoprim; however, there is no substantial clinical evidence to support this claim. It does seem likely that trimethoprim has protected against the emergence of that sulphonamide resistance. This slight benefit is outweighed by the disadvantages of the combination, mainly consisting of the occurrence of adverse events due to the sulphonamide moiety. Consequently, the incidence and severity of the adverse events seen with co-trimoxazole should be reduced by using trimethoprim alone. There are only a few cases where co-trimoxazole is better than trimethoprim: toxoplasmosis, brucellosis, nocardiosis, chancroid and pneumonia due to Pneumocystis carinii. For the other and many common infections, scientific rationale, economic and clinical reasons dictate that trimethoprim is superior to co-trimoxazole.

Multifocal M. intracellulare osteomyelitis in an immunocompetent child

We report the successful treatment of disseminated Mycobacterium intracellulare osteomyelitis, without evidence of other visceral involvement, in a previously healthy, HIV-negative, 2-year-old female using a 23-month regimen of antimicrobial agents that included 18 months of oral therapy with azithromycin, rifabutin, trimethoprim-sulfamethoxazole (TMP/SMX), and ethambutol.

The use of aerosolized pentamidine for prophylaxis of Pneumocystis carinii pneumonia in children with leukemia

We report our experience giving aerosolized pentamidine as prophylaxis for Pneumocystis carinii pneumonia (PCP) to 9 children (mean age, 7.33 years; range 3-17 years) with leukemia who were unable to tolerate trimethoprim-sulfamethoxazole (TMP-SMX) due to allergy or myelosuppression. The dose of pentamidine was modified for each child to correct for weight and approximate alveolar ventilation. We were able to administer the drug to younger children by using a cushioned face mask in place of the standard mouthpiece. One child experienced moderate coughing with administration of pentamidine. He and four others with a past medical history suggestive of reactive airways disease were pretreated with inhaled albuterol. No other adverse effects were noted. Treatment lasted an average of 8.11 +/- 4.1 months per child; no case of PCP occurred. We conclude that aerosolized pentamidine can be administered to even very young children and may be of benefit to all immunosuppressed children unable to use TMP-SMX prophylaxis. The adjusted dose used here appears to be safe, but further studies regarding drug delivery and efficacy are needed.

Acute urinary tract infection in women. What kind of antibiotic therapy is optimal?

Urinary tract infections continue to be a major health problem for women. Understanding of the pathogenesis of urinary tract infections has improved; Staphylococcus saprophyticus has been recognized as a common causative agent, and low-colony-count infections are misdiagnosed less often. Traditional therapy with 10 days of amoxicillin (Amoxil, Wymox) or ampicillin (Omnipen, Totacillin) is no longer considered optimal. For women who fulfill certain clinical criteria, short-course therapy is recommended--preferably 3 days of trimethoprim-sulfamethoxazole, or trimethoprim alone (Proloprim, Trimpex) if the woman is allergic to sulfonamides. Longer therapy is indicated for women with complicated, prolonged, or recurrent infections. To appropriately treat patients and avoid overtreatment that would increase both costs and the incidence of side effects, physicians need to stay abreast of information about pathogens, mechanisms of disease, new drugs, and common resistance patterns.