Use of rifampin in nonstaphylococcal, nonmycobacterial disease

Control of extensively drug-resistant Pseudomonas aeruginosa co-harboring metallo-β-lactamase enzymes with oprD gene downregulation

PURPOSE

to study control and treatment of infection with extensive drug-resistant carbapenem-resistant Pseudomonas aeruginosa (XDR-CRPA).

METHODS

Eleven Pseudomonas aeruginosa (XDR-CRPA) strains used in this study were isolated from a clinical sample, identified, and antibiotics susceptibility recorded in a previous study. Real-time PCR (RT-PCR) was performed to determine the expression level of the OprD gene. Besides, a checkerboard technique was performed to assess the effect of polymyxin-B (POX), colistin (COL), rifampicin (RIF), imipenem (IPM), and meropenem (MEM) during 2 and 3- dimensional antibiotic combinations. Further, the time-kill study was determined for the most potent combination against four representative strains, log₁₀ changes of viable cell counts were expressed as their mean value (±SD) values.

RESULTS

Molecular analysis by Real-time PCR revealed that the diminished expression level of OprD mRNA was overwhelming to various degrees. The checkerboard method demonstrated that the relevant synergism was achieved in 90.9% of strains for both carbapenem antibiotics during the triple combinations. While an additive effect was noted for all the dual regimen assays. Regarding time-kill experiments, a remarkable bactericidal effect with [99.9% killing rate] was observed toward only one strain whilst a bacteriostatic attitude was proven with ≥95% bacterial eradication against the three remaining strains.

CONCLUSIONS

These findings underscore the promising implications of these combinations for treatment against XDR-Pseudomonas aeruginosa even they are resistant to carbapenems due to multiple mechanisms of action.

In vitro antibacterial activity of rifampicin in combination with imipenem, meropenem and doripenem against multidrug-resistant clinical isolates of Pseudomonas aeruginosa

Background

Multidrug-resistant Pseudomonas aeruginosa has emerged as one of the most important healthcare-associated pathogens. Colistin is regarded as the last-resort antibiotic for multidrug-resistant Gram-negative bacteria, but is associated with high rates of acute kidney injury. The aim of this in vitro study is to search for an alternative treatment to colistin for multidrug-resistant P. aeruginosa infections.

Methods

Multidrug and carbapenem-resistant P. aeruginosa isolates were collected between January 2009 and December 2012 at MacKay Memorial Hospital. Minimal inhibitory concentrations (MICs) were determined for various antibiotic combinations. Carbapenemase-producing genes including bla_VIM, other β-lactamase genes and porin mutations were screened by PCR and sequencing. The efficacy of carbapenems (imipenem, meropenem, doripenem) with or without rifampicin was correlated with the type of porin mutation (frameshift mutation, premature stop codon mutation) in multidrug-resistant P. aeruginosa isolates without carbapenemase-producing genes.

Results

Of the 71 multidrug-resistant clinical P. aeruginosa isolates, only six harboured the bla_VIM gene. Imipenem, meropenem and doripenem were significantly more effective (reduced fold-change of MICs) when combined with rifampicin in bla_VIM-negative isolates, especially in isolates with porin frameshift mutation.

Conclusions

Imipenem + rifampicin combination has a low MIC against multidrug-resistant P. aeruginosa, especially in isolates with porin frameshift mutation. The imipenem + rifampicin combination may provide an alternative treatment to colistin for multidrug -resistant P. aeruginosa infections, especially for patients with renal insufficiency.

Rising incidence of Enterococcus species in microbiological specimens from orthopedic patients correlates to increased use of cefuroxime: a study concentrating on tissue samples

BACKGROUND AND PURPOSE

Enterococci are emerging causes of severe infections, including wound and bone infections in orthopedic patients. The main purpose of this study was to determine whether there was a correlation between the incidence of enterococci in tissue samples (biopsies) from orthopedic patients and consumption of cefuroxime in the orthopedic department.

METHODS AND RESULTS

Data were obtained from the department of clinical microbiology and the hospital pharmacy. The consumption of cefuroxime successively increased from 40 defined daily doses (DDD)/10(3) bed days in 2002 to 212 DDD/10(3) bed days in 2009. The incidence of patients with enterococci in tissue samples increased steadily from 1.03/10(3) bed days in 2002 to 5.90/10(3) bed days in 2009. Regression analysis revealed a significant correlation between the consumption of cefuroxime and the incidence of enterococci.

INTERPRETATION

Continuous surveillance of species distribution, resistance rates, and antibiotic consumption is of utmost importance for optimal antibiotic strategy in orthopedic patients.

Current use for old antibacterial agents: polymyxins, rifamycins, and aminoglycosides

This article reviews three classes of antibacterial agents that are uncommonly used in bacterial infections and therefore can be thought of as special-use agents. The polymyxins are reserved for gram-negative bacilli that are resistant to virtually all other classes of drugs. Rifampin is used therapeutically, occasionally as a companion drug in treatment of refractory gram-positive coccal infections, especially those involving foreign bodies. Rifaximin is a new rifamycin that is a strict enteric antibiotic approved for treatment of traveler's diarrhea and is showing promise as a possible agent for refractory Clostridium difficile infections. The aminoglycosides are used mainly as companion drugs for the treatment of resistant gram-negative bacillary infections and for gram-positive coccal endocarditis.

Current use for old antibacterial agents: polymyxins, rifamycins, and aminoglycosides

This article reviews three classes of antibacterial agents that are uncommonly used in bacterial infections and therefore can be thought of as special-use agents. The polymyxins are reserved for gram-negative bacilli that are resistant to virtually all other classes of drugs. Rifampin is used therapeutically, occasionally as a companion drug in treatment of refractory gram-positive coccal infections, especially those involving foreign bodies. Rifaximin is a new rifamycin that is a strict enteric antibiotic approved for treatment of traveler's diarrhea and is showing promise as a possible agent for refractory Clostridium difficile infections. The aminoglycosides are used mainly as companion drugs for the treatment of resistant gram-negative bacillary infections and for gram-positive coccal endocarditis.

Rifamycin lavage in the treatment of experimental intra-abdominal infection

HYPOTHESIS

Peritoneal lavage with rifamycin reduces the number of intraperitoneal bacteria and adhesions and improves the outcome of intra-abdominal infection (IAI).

MATERIAL AND METHODS

Experimental IAI was induced in Wistar rats. After 24 h, the animals underwent relaparotomy. A peritoneal fluid sample was obtained and lavage of the abdominal cavity was performed. Animals were randomly assigned to the three following groups: lavage with 0.9% sodium chloride solution (S group); lavage with rifamycin at the dose of 25 mg/kg (R25 group); and lavage with rifamycin at the dose of 12.5 mg/kg (R12.5 group). Mortality was recorded every 8 h for 7 d. All animals that died had a necropsy. Surviving rats were later sacrificed and also underwent a necropsy. At necropsy, intraperitoneal adhesions were noted and a peritoneal fluid sample was obtained for bacterial analysis.

RESULTS

Peritoneal lavage with rifamycin improved survival from 50% in the S group to 91.7 and 100% in the R25 group and R12.5 group, respectively. Adhesion formation was significantly reduced in the R25 group and R12.5 group compared with the S group (P < or = 0.01 and P < 0.01, respectively). There was a greater reduction in bacterial counts in peritoneal fluid in the R25 group compared with the S group (P = 0.003) but there was no significant difference in the reduction of bacterial count between R25 group and R12.5 group.

CONCLUSION

These results suggest that peritoneal lavage with rifamycin improves the outcome of IAI.

New C25 carbamate rifamycin derivatives are resistant to inactivation by ADP-ribosyl transferases

A novel series of 3-morpholino rifamycins in which the C25 acetate group was replaced by a carbamate group were prepared and found to exhibit significantly improved antimicrobial activity than rifampin against Mycobacterium smegmatis. Further characterization of such compounds suggests that relatively large groups attached to the rifamycin core via a C25 carbamate linkage prevent inactivation via ribosylation of the C23 alcohol as catalyzed by the endogenous rifampin ADP-ribosyl transferase of M. smegmatis. SAR studies of the C25 carbamate rifamycin series against M. smegmatis and other bacteria are reported.

Monitoring in vivo fitness of rifampicin-resistant Staphylococcus aureus mutants in a mouse biofilm infection model

OBJECTIVES

To investigate in vivo fitness of rifampicin-resistant Staphylococcus aureus mutants in a mouse biofilm model using bioluminescence imaging.

MATERIALS AND METHODS

S. aureus was engineered with a luciferase operon to emit bioluminescence that can be detected in vivo using an IVIS imaging system. Two rifampicin-resistant strains of S. aureus that were previously isolated from animals undergoing rifampicin treatment, S464P (resistant to low concentrations of rifampicin) and H481Y (resistant to high concentrations of rifampicin), were characterized and then compared with their parental strain for in vivo fitness to form biofilm infections in the absence of rifampicin.

RESULTS

The mutant S464P showed better adaptation to in vivo growth than either the parental strain or H481Y without selective pressure. Six days after implanting pre-colonized catheters, bioluminescent signals were seen from 100% of the catheters coated by the mutant S464P. In comparison, only 83% and 61% of the catheters coated by the parental strain and H481Y, respectively, maintained a signal in vivo. Rifampicin treatment of S464P biofilms in vivo resulted in a slight decline, but earlier rebound in bioluminescence from these catheters compared with the parental signal, whereas rifampicin had no affect on bioluminescence in mice infected with mutant H481Y.

CONCLUSIONS

The mutant with low-level rifampicin resistance appears to be better adapted to in vivo growth than the mutant that has high-level rifampicin resistance. Moreover, the former mutant may actually have a slight competitive advantage over the rifampicin-susceptible strain (parental), raising awareness for the occurrence of such strains in clinical environments.

Current use for old antibacterial agents: polymyxins, rifampin, and aminoglycosides

This article discusses three classes of antibacterial agents that are uncommonly used in bacterial infections (other than mycobacterial infections) and can be thought of as special-use agents. These are the polymyxins, rifampin, and the aminoglycosides.

Antimicrobial durability and rare ultrastructural colonization of indwelling central catheters coated with minocycline and rifampin

OBJECTIVE

To determine the duration of antimicrobial activity and the efficacy of indwelling catheters coated with minocycline and rifampin in preventing ultrastructural colonization.

DESIGN

Multicenter, prospective, randomized, clinical trial.

SETTING

Five university-based medical centers.

PATIENTS

Cohort 1 consisted of 40 randomized patients in whom an equal number of minocycline- and rifampin-coated and uncoated catheters were inserted and studied using scanning electron microscopy. Cohort 2 consisted of 118 patients who received coated catheters that were tested for the antimicrobial activity and levels of the antibiotics at the time of removal.

INTERVENTIONS

Catheters pretreated with tridodecylmethylammonium chloride and subsequently coated with minocycline and rifampin; uncoated catheters (control).

MEASUREMENTS AND MAIN RESULTS

Quantitative scanning electron microscopy was utilized to determine both the ultrastructural colonization in biofilm on coated and uncoated catheters. The zones of inhibition of coated catheters from studied patients against Staphylococcus epidermidis was used to determine the antimicrobial durability. High-performance liquid chromatography was used to determine antibiotic levels on indwelling coated catheters and in serum. Mild-to-heavy ultrastructural colonization was detected in 7 (35%) of 20 coated catheters and in 16 (80%) of 20 uncoated catheters (p = .004). Significant antimicrobial inhibitory activity against S. epidermidis was maintained for 16 days. Rifampin and minocycline continued to be detected on the surfaces of coated catheters for at least 2 wks after placement. Neither antibiotic was detected in the 60 serum samples obtained from 15 patients during catheterization.

CONCLUSION

Coating catheters with minocycline and rifampin inhibits ultrastructural colonization of indwelling catheters and maintains effective antimicrobial activity for at least 2 wks.

Electron microscopy and serological features of a patient with Q fever prosthetic valve endocarditis

The clinical, serological and electron microscopic findings in a 47 year old woman with bioprosthetic valve coxiella endocarditis occurring 15 years after streptococcal endocarditis are described. The patient underwent valvular surgery a total of four times to control symptoms and remains well on medical therapy more than two years after her last operation.

Addition of rifampin to cephalexin therapy for recalcitrant staphylococcal skin infections--an observation

We report two pediatric patients with recalcitrant staphylococcal infections whose infections resolved when rifampin was added to standard antistaphylococcal therapy. One patient had a post-varicella staphylococcal ulcerative lesion and did not respond to cephalexin alone but did respond when rifampin was added. A second patient had staphylococcal bullous impetigo and did not respond to dicloxacillin or cephalexin but did respond when rifampin was added to the cephalexin. If a patient fails to respond to traditional antistaphylococcal therapy, the addition of rifampin may be beneficial.

Rifampin-fluconazole interaction in critically ill patients

OBJECTIVE

To report the influence of rifampin coadministration on the pharmacokinetics of fluconazole in 2 critically ill patients.

CASE SUMMARIES

The pharmacokinetics of fluconazole are reported in 5 patients in the intensive care unit (ICU), 2 of whom received rifampin and 3 who received only fluconazole. Patient 1 was a 52 year-old man with bilateral pneumonia who received rifampin for 9 days in addition to other antibiotics when fluconazole was added for suspected fungal superinfection. Patient 2, a 39-year-old man with steroid-dependent asthma was admitted to the ICU with a right middle lobe pneumonia and ventilatory insufficiency. Because of rapid clinical deterioration, intravenous rifampin 600 mg q12h and fluconazole 100 mg q24h were added to conventional antibacterial therapy. Patients 3-5 received intravenous fluconazole therapy, but were never administered rifampin prior to their antifungal therapy.

DISCUSSION

Fluconazole has gained wide use as an antifungal agent because of its efficacy, limited toxicity, and the paucity of reported drug interactions. In some clinical situations, however, the drug must be coadministered with rifampin. Limited data in healthy volunteers suggest that the coadministration of rifampin and fluconazole results in a 23% reduction in the fluconazole area under the concentration-time curve (AUC). In this report, we found a statistically significant lowering of the AUC (52%) and a 93% higher total body clearance of fluconazole in patients treated with rifampin.

CONCLUSIONS

Although limited data are available describing the magnitude of the interaction between fluconazole and rifampin in patients, our data suggest a more significant interaction than previously reported. If the concurrent administration of the 2 drugs in unavoidable, the patient's clinical response to treatment should be monitored closely, as the unexpectedly large reduction in fluconazole serum concentrations may lead to poor treatment outcomes.