Efficacy of a broad-spectrum antibiotic (mupirocin) in an in vitro model of infected skin

Stability-indicating RP-HPLC method development and validation for estimation of Mupirocin calcium in bulk and in pharmaceutical formulation

Background

A simple, rapid, sensitive and selective stability-indicating (RP-HPLC) method is suggested for the determination of Mupirocin calcium in bulk drug and in pharmaceutical formulation. Mupirocin calcium was eluted from a PrincetoneSPHER-100 C8 (250 × 4.6 mm, 5 µm) column with mobile phase consisting of methanol and water (75:25 v/v) pH adjusted to 4 with acetic acid. The gradient was optimized with a flow rate of 1 mL/min and a wavelength of 221 nm.

Result

The complete analytical method validation was successfully carried out as per ICH guidelines. The retrieval study was carried out at 80% to 120% level of working concentration, and results were in the range of 99 to 101%. The linearity was proven in range of 4–24 µg/mL of working concentration with linear regression curve (R2 = 0.999) with limits of detection (LOD) and quantitation (LOQ) being 0.35 and 1.08 µg/mL, respectively. The retention time for Mupirocin calcium was 5.09 min. The method shows good recoveries and intra-day and inter-day relative standard deviations were less than 2%. Validation parameters as ruggedness and robustness were also determined as per ICH guidelines and were found to be satisfactory. For stability study, the drug was exposed to various stress conditions such as acid, base, oxidation and sunlight as per recommendations of ICH guidelines.

Conclusion

The developed HPLC method could be successfully used for the estimation of Mupirocin calcium in bulk and in Pharmaceutical formulation. The high recovery and low relative standard deviation confirm the suitability of proposed method that can be employed for the routine analysis in bulk and Pharmaceutical formulation.

The effect of mupirocin dressings on postoperative surgical site infections in elective colorectal surgery: A prospective, randomized controlled trial

BACKGROUND

Surgical site infections (SSIs) are the most common nosocomial infection among surgical patients. We hypothesized that mupirocin ointment would decrease SSI rates compared to standard surgical dressings in patients undergoing colorectal surgery.

METHODS

A prospective randomized controlled trial was performed, including patients undergoing elective open and minimally invasive colorectal surgery. Patients were randomized 1:1 to receive standard gauze dressings or mupirocin ointment (2%) dressings. The primary outcome was incisional SSI at 30 days postoperative.

RESULTS

A total of 192 patients were enrolled; 150 underwent randomization: 75 to the mupirocin arm, and 75 to the standard gauze dressing arm. Three SSIs occurred; one (1%) in the mupirocin group, and two (3%) in the standard gauze group (P = 0.560). There was no significant difference between standard gauze dressings and mupirocin dressings.

CONCLUSION

Mupirocin (2%) ointment failed to show a benefit compared to standard dressings for postoperative SSI.

A veterinary perspective on methicillin-resistant staphylococci

OBJECTIVE

To familiarize the reader with the epidemiology, diagnosis, and infectious and zoonotic potential of methicillin-resistant staphylococci.

DATA SOURCES

Original research publications, scientific reviews and abstracts, case reports, and conference proceedings.

HUMAN DATA SYNTHESIS

Staphylococcus aureus is a common human commensal organism; acquisition of genes encoding an altered penicillin-binding protein confers resistance to beta-lactam antimicrobial drugs. Methicillin-resistant S. aureus (MRSA) are often resistant to non-beta-lactam antimicrobial drugs as well. Originally described as an important cause of nosocomial infection, MRSA colonization and infection are now often identified in humans outside healthcare settings. Like other S. aureus, MRSA may be present without clinical illness. However, when they do cause infection the consequences can be extremely serious.

VETERINARY DATA SYNTHESIS

The major domestic animal species, including pets and livestock, may become contaminated, colonized, or infected with methicillin-resistant staphylococci, including MRSA. Dogs and cats are more likely to be colonized/infected with Staphylococcus pseudintermedius than S. aureus, but this pathogen can acquire genes encoding methicillin resistance (ie, MRSP). Diagnosis of MRSA or MRSP has implications not only for treatment of infected animals, but for potential zoonotic transmission.

CONCLUSIONS

MRSA infection is an important cause of morbidity and mortality in humans. Animals may be contaminated, colonized, or infected with MRSA, with implications for the animal's health and as a potential reservoir for human infection. Staphylococci other than S. aureus may also acquire genes for methicillin resistance, and these species can also result in animal and occasionally human morbidity or mortality.

Bactericidal activity of flucloxacillin against Staphylococcus aureus in primary keratinocyte cultures of lesional and unaffected skin of patients suffering from atopic dermatitis

More than 90% of patients with atopic dermatitis (AD) are colonized by Staphylococcus aureus. Due to prevalent multi-resistant strains, it is highly difficult to eliminate S. aureus contamination of primary cell cultures of human AD skin by means of the antibiotics commonly used in cell culture. Therefore, an anti-staphylococcal treatment was investigated by which sterile proliferating keratinocyte cultures are attained from lesional and unaffected skin of AD patients by applying flucloxacillin, which in general is systemically used in vivo. The treatment with 1% flucloxacillin for 20 min included both colonized skin samples and contaminated primary cell cultures. In the case of persistent contamination, this step was repeated as often as required until complete decontamination without any cytotoxic indications was achieved. Antibacterial treatment with flucloxacillin permitted the cultivation of sterile, vital, and proliferating primary cultures of human skin keratinocytes from lesional and unaffected skin of AD patients with S. aureus colonization. The method increased the success rate of isolation of AD keratinocytes from 30 to 90%, representing on average 3 vs. 9 successfully isolated, sterile and proliferating cultures out of 10 contaminated skin biopsies, which is comparable to normal human keratinocyte isolation rates.

Comparison of silver sulfadiazine 1%, mupirocin 2%, and fusidic acid 2% for topical antibacterial effect in methicillin-resistant staphylococci-infected, full-skin thickness rat burn wounds

Silver sulfadiazine 1%, mupirocin 2%, and fusidic acid 2% were compared to assess the antibacterial effect of a once-daily application on experimental rat 15% full-skin thickness burn wounds seeded 24 hours earlier with a 10 standard strain of methicillin-resistant staphylococci. The quantitative counts of seeded organism in burn eschar and subjacent muscle were determined at postburn day 7, beside the cultures of blood and lung biopsies. All tested topical agents were equally effective against methicillin-resistant in reducing local burn wound bacterial count and preventing systemic infection.

Perianal candidosis--a comparative study with mupirocin and nystatin

OBJECTIVE

To assess the efficacy and clinical outcome of 2% mupirocin in a polyethylene glycol base and nystatin cream as treatment regimens in diaper candidosis.

DESIGN

A prospective randomized comparative study.

METHODS

In vitro. The susceptibility of 20 clinical isolates of Candida albicans to 2% mupirocin, nystatin, and five additional antifungal agents was evaluated using the Nathan agar-well diffusion assay. The minimum inhibitory concentration (MIC) of mupirocin against the Candida species was determined using a tube dilution method. In vivo. Twenty patients (mean age, 12 months; range, 1 month to 4 years) with moderate to severe Monilia diaper dermatitis either had mupirocin ointment or nystatin cream applied to the infected area every 8 h or after every diaper change for a period of 7 days. Microscopic examination of skin scrapings and mycologic and microbiological cultures were performed before treatment and daily for 7 days, and progress was clinically assessed.

RESULTS

In vitro. Topical mupirocin produced a greater zone of inhibition than nystatin cream, i.e. a mean of 27.2 mm (SD 1.55) compared with a mean of 17.3 mm (SD 1.08) for nystatin cream. MIC for mupirocin of 512 microg/mL in one case, 256 microg/mL in six cases, 200 microg/mL in 10 cases and 400 microg/mL in three cases were obtained for the 20 clinical isolates. C. albicans also displayed a universal sensitivity to mupirocin and nystatin. In vivo. Eradication of all Candida organisms was achieved within 2-6 days (mean, 2.6 days) in 10 patients receiving topical mupirocin therapy with rapid healing of the excoriated wounds (mean, 4.7 days). Both Gram-positive and Gram-negative bacteria were eradicated from the infected area within the trial period. Ten patients received topical nystatin cream and, in each case, Candida was successfully cleared within 5 days (mean, 2.8 days). Only three wounds were clinically healed within the trial period, however. The remaining seven wounds showed evidence of improved, but ongoing excoriated dermatitis and a heavy growth of polymicrobial organisms.

CONCLUSIONS

Both agents eradicated Candida, the major difference being the marked response of the diaper dermatitis to mupirocin. Mupirocin should be applied topically 3-4 times daily or with each diaper change and is an excellent antifungal agent.

Opportunities for mupirocin calcium cream in the emergency department

Mupirocin calcium cream is a newly reformulated topical antibiotic with a bactericidal spectrum specific for the pathogens that frequently cause secondary infections in superficial wounds. Both the calcium cream and ointment formulations have demonstrated efficacy in the treatment of secondarily infected traumatic lesions and dermatoses, including eczema, burns, wounds, bites, and ulcers. Mupirocin has a low risk of systemic and topical complications. To date, antimicrobial resistance is rare among target pathogens. The use of mupirocin to treat secondary wound infection has a profile of high efficacy and does not impair the normal healing in traumatized skin.

Secondarily infected wounds and dermatoses: a diagnosis and treatment guide

Secondary bacterial skin infections are common complications of primary dermatoses, primary nonbacterial skin infections, traumatic lesions, ulcers, cutaneous infestations, and other miscellaneous skin diseases. Most diagnoses are based on information obtained by patient history and physical examination. Secondary bacterial skin infections may be polymicrobial, commonly include the pathogens Staphylococcus aureus and Streptococcus pyogenes, and require proper antibiotic treatment. The use of topical antibiotics avoids the risk of systemic allergic reactions or generalized side effects, and provides a high antibiotic concentration at the site of infection. Therefore, topical antibiotics should be considered as potential primary therapy in the emergency department. When systemic therapy is indicated, most commonly used agents for secondary skin infections are the penicillinase-resistant semi-synthetic penicillins; the first-generation cephalosporins, the macrolides; and combination antibacterials, such as amoxicillin/ clavulanate potassium and trimethoprim/sulfamethoxazole.

Killing effects of antibiotics and two-fold antimicrobial combinations on proliferating and non growing staphylococci

Antimicrobial agents are generally tested against bacteria in the log phase of multiplication to produce the maximal bactericidal effect. In case of foreign body infections, bacteria may multiply less optimally. We examined the effects of several classes of lipophilic antistaphylococcal agents to determine their antimicrobial activity towards coagulase-positive and coagulase-negative staphylococci during the non-growing and slowly growing phases. Only two-fold combinations containing rifampicin were bactericidal (3-log kill) against Staphylococcus aureus. This was in contrast to growing bacteria in the log phase, in which a variety of antibiotics produced relevant killing. Concerning the staphylococci examined, antibiotic killing was greatly dependent on the growth rate. Most of the two-fold combinations containing rifampicin showed additive and synergistic antibacterial activity both in growth and stationary states as measured by the killing kinetics. The theoretical and clinical implications of delayed killing by chemotherapeutic agents for established bacterial infections and infections involving foreign bodies are discussed. Antimicrobial combinations including rifampicin and a second lipophilic antistaphylococcal drug may be most promising and appropriate as coating substances for intravascular devices or for clinical application in cases of implant infections.

Methicillin-resistant Staphylococcus aureus versus the burn patient

Methicillin-resistant Staphylococcus aureus (MRSA) has become a frequent cause of nosocomial infection, its increasing prevalence posing serious therapeutic and infection control problems within the hospital environment. MRSA is a major challenge to the burn patient, with potential to cause significant morbidity and mortality. Burn patients have been shown to become colonised and infected more readily than other patient groups. Extensive burn injuries are particularly susceptible to infection as a result of the disruption of the normal skin barrier and accompanying depression of immune responses. Extended hospitalisation and antibiotic therapy have been identified as additional risk factors for MRSA carriage and infection. Microbial surveillance, epidemiological studies and the introduction of strict infection control regimes can reduce the prevalence of MRSA but may be insufficient for eradication or prevention of outbreak situations. Recognition of the clinical importance of MRSA to the burn patient highlights the need to take appropriate measures to minimise transmission and infection in this vulnerable group of patients.

Development of a new CSF-shunt with sustained release of an antimicrobial broad-spectrum combination

The use of Cerebro-Spinal-Fluid-shunts (CSF-shunts) is often associated with infectious complications, because bacteria tend to colonize plastic material. The use of plastic materials with antibacterial activity may reduce catheter related bacterial colonization. A novel CSF-shunt impregnated with a broad-spectrum antimicrobial combination was designed in order to meet two requirements; lack of toxicity and persistence of antimicrobial efficacy. Incorporation of three antibiotics up to 10% (wt/wt) into the shunt material (polydimethyl-siloxane) was required for sustained release for more than 100 days, measured by HPLC. The combination of antimicrobials showed additive and synergistical effects as measured by the checker-board and time kill technique. These antimicrobial combinations prevented mutations in resistance inducing experiments with several S. epidermidis and S. aureus strains. Using large challenge doses of S. aureus in a catheter colonization model, antimicrobially modified catheters were protected against bacterial colonization for more than 14 days. Using a C3a-des-Arg-ELISA-test and a CH50-hemolysis test the modified catheter was as biocompatible as the unmodified shunt material. These encouraging results indicate that such antibiotic-bonded catheters substantially reduce the incidence and magnitude of catheter-related bacterial colonization and may substantially reduce CSF-shunt infection.