The role of methicillin-resistant Staphylococcus aureus in orthopaedic implant surgery

Incidence of Urinary Tract Infection Following Transrectal Ultrasound Guided Prostate Biopsy at a Tertiary-Care Medical Center in Lebanon

Objective:

To determine the incidence of urinary tract infections (UTIs) following transrectal ultrasound guided needle biopsy of the prostate (TRUBP) and the bacteriology of these infections.

Design:

Retrospective evaluation of the charts and records of all patients who underwent TRUBP between June 1, 2002, and August 31, 2003.

Setting:

American University of Beirut Medical Center, a tertiary-care center in Lebanon.

Patients:

Two hundred seven patients underwent TRUBP. All received prophylactic antibiotics. One hundred twenty (58%) received ciprofloxacin alone, whereas 87 (42%) received both ciprofloxacin and gentamicin. Sixty-one patients (29.5%) had an enema prior to the procedure, whereas 146 (70.5%) did not.

Results:

Thirteen patients (6.3%) were admitted with UTI. All had rigors and fever on admission. Symptoms appeared at a mean of 2.7 days and the mean hospital stay was 9.2 days. The mean duration of antibiotic treatment was 23.2 days. Ten (77%) of the patients had positive bacteriology. Urine cultures were positive in 8 (61.5%) of the patients and blood cultures in 6 (46.2%). All positive cultures grew Escherichia coli resistant to ciprofloxacin, with 5 isolates producing extended-spectrum beta-lactamases.

Conclusions:

TRUBP continues to be associated with significant infectious complications, especially UTI. Given the increasing incidence of antibiotic resistance mainly among the Enterobacteriaceae, antimicrobial prophylaxis practices should be reevaluated and the universal administration of quinolones alone or in combination with aminoglycosides should be reconsidered.

Cis-2-decenoic acid inhibits S. aureus growth and biofilm in vitro: a pilot study

BACKGROUND

Cis-2 decenoic acid (C2DA) disperses biofilm in many strains of microorganisms. However, whether C2DA inhibits bacterial growth or has potential to boost the actions of antibiotics is unknown.

QUESTIONS/PURPOSES

We asked whether (1) C2DA inhibited MRSA growth and biofilm, (2) antibiotics increased inhibitory effects, (3) inhibitory concentrations of C2DA were cytotoxic to human cells, and (4) effective concentrations could be delivered from a chitosan sponge drug delivery device.

METHODS

Broth containing seven concentrations of C2DA and six concentrations of either daptomycin, vancomycin, or linezolid was inoculated with a clinical isolate of MRSA and added to a total of 504 coated microtiter plate wells in triplicate (n = 3) for turbidity bacterial growth and crystal violet biofilm mass quantification. We used fibroblast cell viability assays of six C2DA concentrations (n = 4) to evaluate preliminary biocompatibility. We measured the elution of C2DA from a chitosan sponge drug delivery device with two representative loading concentrations (n = 3).

RESULTS

C2DA at concentrations of 500 μg/mL and above inhibited growth, while 125 μg/mL C2DA inhibited biofilm. Combination with antibiotics increased these effects. At concentrations up to 500 μg/mL, there were no cytotoxic effects on fibroblasts. Chitosan sponges loaded with 100 mg of C2DA eluted concentrations at or above biofilm-inhibitory concentrations for 5 days.

CONCLUSIONS

C2DA inhibited biofilm formation by MRSA at biocompatible concentrations, with increasing biofilm reduction with added antibiotics. Elution of C2DA from a chitosan sponge can be modified through adjusting loading concentration.

CLINICAL RELEVANCE

By inhibiting biofilm formation on implant surfaces, C2DA may reduce the number of infections in musculoskeletal trauma.

MRSA colonisation in patients with proximal femur fractures in a German trauma centre: incidence, infection rates and outcomes

PURPOSE

The aim of this study was to assess the incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonisation in patients admitted into a level 1 German trauma centre with proximal femur fractures, to correlate this incidence with defined risk factors for MRSA colonisation and to determine its influence on morbidity and mortality.

METHODS

Between August and November 2006, 65 patients were included in the study. Cotton-tipped swab samples were taken from the nose, throat, groin and any skin defects in the emergency room. The following factors were recorded: age, gender, any concomitant diseases, the fracture type and treatment device, skin lesions, hospitalisation within the last year, any urinary or vascular catheters, a nasogastric or gastrostomy tube, an ileal stoma, the use of a respirator and antibiotic therapy within the last year. During follow-up, data concerning any surgical site infections; any chest, urinary or vascular catheter infections; the success of decontamination and death within 1 year after surgery were collected.

RESULTS

The risk factors for MRSA colonisation were positive in 40 patients. The incidence of MRSA colonisation was 17%, which is higher than in most comparable studies but consistent with some very recent publications. The nosocomial infection rates, surgical site infection rates and mortality within the 1-year follow-up period were significantly higher in the MRSA-colonised patients.

CONCLUSION

The high incidence of MRSA in this study supports the need for systematic detection of MRSA-colonised patients. In our hospital, any patient with positive risk factors for MRSA colonisation is swabbed in the emergency room and treated as MRSA positive until proven otherwise.

The prevalence of meticillin-resistant Staphylococcus aureus in long-term care facilities: is there a need for tailored glycopeptide prophylaxis?

Prophylactic antibiotics are effective in reducing the rate of surgical site infection (SSI). Cephalosporin antibiotics are recommended except for patients colonised with meticillin resistant staphylococcus aureus (MRSA), where glycopeptide antibiotics are indicated. However, in the trauma setting, the MRSA status is unknown prior to surgery.

Aim: To determine if the incidence of MRSA colonisation in trauma patients from long term care (LTC) warrants the use of empirical glycopeptide antibiotics.

Methods: A retrospective analysis of patients admitted with hip fractures was performed. The MRSA status of patient from LTC facilities and home was determined.

Results: The prevalence of MRSA colonisation in patients admitted from LTC facilities was 33.6%, compared to 3.6% for patients admitted from home, P < 0.001.

Our results suggest that risk of patients carrying MRSA is significantly higher for patients being admitted form LTC. This group of patients may benefit from empirical glycopeptide antibiotic when the MRSA status is unknown.

Methicillin-resistant Staphylococcus aureus in orthopaedic surgery

Methicillin-resistant Staphylococcus aureus (MRSA) has become a ubiquitous bacterium in both the hospital and community setting. There are two major subclassifications of MRSA, community-acquired and healthcare-acquired, each with differing pathogenicity and management. MRSA is increasingly responsible for infections in otherwise healthy, active adults. Local outbreaks affect both professional and amateur athletes and there is increasing public awareness of the issue. Health-acquired MRSA has major cost and outcome implications for patients and hospitals. The increasing prevalence and severity of MRSA means that the orthopaedic community should have a basic knowledge of the bacterium, its presentation and options for treatment. This paper examines the evolution of MRSA, analyses the spectrum of diseases produced by this bacterium and presents current prevention and treatment strategies for orthopaedic infections from MRSA.

Prophylactic antibiotics in orthopaedic surgery

The use of prophylactic antibiotics in orthopaedic surgery is effective in reducing surgical site infections in hip and knee arthroplasty, spine surgery, and open reduction and internal fixation of fractures. To maximize the beneficial effect of prophylactic antibiotics while minimizing adverse effects, the correct antimicrobial agent must be selected, the drug must be administered just before incision, and the duration of administration should not exceed 24 hours.

Early experience with linezolid for infections in orthopaedics

In infections following orthopaedic surgery, isolated staphylococci are reported to be methicillin resistant (MRSA) in up to 50% of cases. Linezolid, the first in a new class of antibiotics, has excellent efficacy against gram positive organisms that are resistant to other therapies and is 100% orally bioavailable. We report early results of its use for the treatment of resistant infections in orthopaedic practice. Infections were characterised according to the UK Nosocomial Infections National Surveillance Service classification of surgical infections as superficial, deep or organ/space. Osteomyelitis, joint sepsis and deep infection involving orthopaedic implants were included into the final category. Outcome was recorded as clinical, microbiological and blood parameter cure or fail. Over the 12-month study period, 54 patients received linezolid therapy, 41% of these had significant co-morbidity that might affect their ability to fight infection. Sixty-seven percent of infections were in association with implanted metal work. The majority of patients were treated with vancomycin for a short period before linezolid was used as oral 'switch' therapy for longer-term administration, allowing early discharge in all cases. MRSA was isolated in 87% of the patients treated. The mean length of linezolid therapy was 39 days (2-151). Clinical success was achieved in 90% of patients overall. Though there were no life-threatening complications, adverse event rates were significantly higher than those recorded in the literature, with 19% of patients needing to cease therapy. Linezolid offers an alternative to traditional treatments for resistant infections and can facilitate early discharge. Patients need to be monitored closely, particularly where long-term therapy is planned.

Role of topical antibiotics in hip surgery. A prospective randomised study

BACKGROUND

The effectiveness of topical antibiotics has been shown well enough in vitro to justify strong consideration of their use in orthopaedic procedures. We carried out a randomised prospective trial to study the role of topical chloramphenicol ointment application on postoperative wounds following surgeries for hip fractures.

METHODS

One hundred cases with fracture neck of femur were enrolled in the study. They were randomized into two treatment groups: one group had chloramphenicol ointment applied at the surgical site at the end of procedure and 3rd day postoperatively, while the control group did not. The wound was checked on the 3rd, 6th, 12th and 30th days postoperatively, by a tissue viability nurse on the guidelines issued by the Scottish Centre for Infection and Environmental Health (SCIEH).

RESULTS

We had 12 cases with superficial infection of which 8 belonged to control group. The risk of developing wound infection, however, was not significant with and without the use of chloramphenicol ointment (relative risk 0.430, 95% confidence interval (CI) 0.120-1.544). Using multivariate analysis, no association was found between wound infection and age, gender, type of fracture or type of surgical procedure. Smoking was found to be the only factor significantly associated with infection, with the relative risk for current smokers compared with former/non-smokers being 7.29 (95% CI 1.62-32.67).

CONCLUSION

Awareness is needed amongst the general public about the ill effects of smoking. There was reduction in the incidence of wound infection with the use of topical antibiotic ointment. However, this was not statistically significant to recommend its use in routine practice. A larger study should provide useful information on the role of topical antibiotic and its effect on postoperative wound infection.