Changes in susceptibilities to teicoplanin, vancomycin and other antibiotics among Staphylococcus aureus isolates in a tertiary-care University hospital

Topical Vancomycin for Prevention of Surgical Site Infection in Cranial Surgeries: Results of an Updated Systematic Review, Meta-Analysis and Meta-Regression

Background

Surgical site infection (SSI) rates (1-9%) remain high despite the widespread adoption of infection control bundles. Topical vancomycin has emerged as an effective strategy to reduce the rate of SSI in patients undergoing spinal surgery including instrumentation. However, its use and efficiency in cranial neurosurgery is not well established. The aim of this study is to study the efficacy of topical vancomycin in cranial neurosurgery.

Methods

A systematic search was performed according to Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Data regarding type of surgery, use of implants, the dose of vancomycin, technique of administration in each study, outcomes, rate of SSI, and the interval between surgery and SSI; possible complications related to antibiotic use were collected.

Results

A total of 12 studies were included in the qualitative analysis with 3,446 patients. SSI developed in 1.6% of the patients in the vancomycin group as compared to 5.28% in the control group. The pooled risk ratio was 0.24 with 95% CI: 0.12-0.51 (P-value: <0.00001). The difference between the subgroups was significant (P-value: < 0.00001). The number needed to treat (NNT) was 27.2. The studies showed low heterogeneity with an I2 of 24%. Meta-regression analysis showed that the number of patients in a study, duration of follow-up, and year of publication did not contribute significantly to effect size.

Conclusion

The limited systemic absorption of vancomycin and broad-spectrum led to its widespread applicability in the prevention of SSI in all types of cranial neurosurgery. Cases with implantable pulse generators, cranioplasty, and cerebrospinal fluid (CSF) diversion procedures have all demonstrated their unequivocal effectiveness.

Vancomycin prophylaxis of surgical site infection in clean orthopedic surgery

Community-acquired methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as a public health concern since the mid-1990s. Because of the increase in reports of this pathogen, it has become increasingly tempting for clinicians to provide prophylaxis against this entity using antibiotics known to be effective against MRSA. The goal of this study was to assess the use of MRSA prophylaxis to determine whether it is safe and effective. A systematic search of the literature was performed to identify articles that examined the use of vancomycin in clean orthopedic surgery. Infection rates and adverse events were extracted, and the data were aggregated and analyzed using a DerSimonian and Laird random effects model. Publication bias and study quality were also assessed. No benefit of parenteral administration of vancomycin was identified. Local, vancomycin-impregnated cement and powder are associated with lower infection rates. Few adverse events occurred, and most of those that occurred involved infusion rate.Cost, resistance, and side effects are concerns in using vancomycin therapy in addition to standard antibiotic prophylaxis. Given the lack of efficacy of intravenous vancomycin, the authors do not recommend its routine use in clean orthopedic surgery. However, local administration appears to be safe and effective. The data are most compelling in orthopedic spine surgery in which a patient without prophylaxis is more than 4 times as likely to have a deep postoperative wound infection compared with a patient who received local vancomycin. The authors recommend the use of local antibiotics when possible in clean orthopedic surgery.

Identification of a Variant "Rome Clone" of Methicillin-ResistantStaphylococcus aureuswith Decreased Susceptibility to Vancomycin, Responsible for an Outbreak in an Intensive Care Unit

We describe the identification of a variant of the "Rome clone" of methicillin-resistant Staphylococcus aureus (MRSA), responsible for an outbreak involving 5 patients in a Cardiac Surgery Intensive Care Unit (CS-ICU) of a tertiary-care University Hospital in Rome. All strains isolated from patients and from nasal swabs obtained from four members of the CS-ICU personnel, belonged to the same identified clone. The characteristics of this clone were: (1) resistance to ampicillin, oxacillin, gentamicin, ciprofloxacin, erythromycin, clindamycin, rifampin, spectinomycin, and tetracycline; (2) vancomycin and teicoplanin MICs respectively of 2 and 4 mg/L; (3) heteroresistant subpopulations in the presence of 4 and 6 mg/L of vancomycin (10(-3) and 10(-5), respectively); (4) clonal type I::J::C determined following an established protocol (mec A::Tn 554 ::PFGE); (5) sequence type ST247 (3-3-1-12-4-4-16), obtained by multilocus sequence typing (MLST); and (6) the staphylococcal cassette chromosome mec (SCC) IA, obtained by multiplex PCR method. This new strain had different characteristics from the epidemic clone circulating in the same hospital from 1997 and designed "Rome clone," which was susceptible to erythromycin, clindamycin, and spectinomycin and belonged to the II::NH::C genetic background. A high genetic similarity between this Rome clone and the previously classified Archaic and Iberian clones was found, because they shared the same allelic profile (ST247), probably originating from the same S. aureus ancestor of the Iberian MRSA strains. Therefore, the strains responsible for the outbreak, with vancomycin MICs 2-4 mg/L, are variant clones, showing the genotype of the "Rome clone," the ST247 in association with SCC mec type IA (ST247-MRSA-IA), and are characterized by a uniform susceptibility to fosfomycin.

Activity of moxifloxacin in combination with vancomycin or teicoplanin against Staphylococcus aureus isolated from device-associated infections unresponsive to glycopeptide therapy

We tested the in vitro bactericidal activity of moxifloxacin, a new 8-methoxyquinolone, alone and in combination with vancomycin or teicoplanin at different multiples of minimum inhibitory concentration (MIC) against 8 methicillin-ciprofloxacin-resistant Staphylococcus aureus (M-C-RSA) and 1 methicillin-ciprofloxacin susceptible S. aureus (M-C-SSA) recently isolated from device-associated infections unresponsive to or relapsing after glycopeptide therapy, despite device removal. MICs of vancomycin ranged from 1 to 4 microg/ml, MICs of teicoplanin ranged from 2 to 8 microg/ml; MICs of moxifloxacin were always 2 microg/ml against M-C-RSA isolates and 0.125 microg/ml against the M-C-SSA isolate. The 9 strains resulted tolerant when tested for vancomycin, teicoplanin, and moxifloxacin used alone at 2 x MIC. In all cases the combination of moxifloxacin and teicoplanin or vancomycin appeared to be bactericidal already at MIC concentration for glycopeptides plus 0.5 x MIC concentration for moxifloxacin. If these results are confirmed in vivo in animal experiments, the combination of moxifloxacin with glycopeptides might be useful for treating device-associated infections, and in preventing the frightening phenomenon of increasing MICs for glycopeptides.

A closer look at vancomycin, teicoplanin, and antimicrobial resistance

The worldwide increase in the incidence of resistant Gram-positive infections has renewed interest in the glycopeptide class of antimicrobial agents. Two glycopeptides are available in many parts of the world--vancomycin and teicoplanin. These two agents appear to differ in several respects, including: potential for selecting microbial resistance, dosing convenience, safety, and efficacy in severe infection. Teicoplanin appears to have lower toxicity and greater convenience; however, its widespread acceptance has been plagued by concerns over antimicrobial resistance, efficacy, and appropriate dosing. A review of available studies suggests that teicoplanin, when dosed at 6 mg/kg/day, is better tolerated than vancomycin 15 mg/kg/q12h; however, at these doses, it appears to be somewhat less effective than vancomycin in serious Staphylococcus aureus infection, such as endocarditis. Although higher doses of teicoplanin, 12 mg/kg/day to 30 mg/kg/day, have been associated with efficacy comparable to that of vancomycin in serious S. aureus infections, such doses may eliminate some of the safety advantages conferred by lower teicoplanin doses. Teicoplanin has been associated with resistance among coagulase-negative staphylococci and the selection of resistance in S. aureus. There is some evidence that widespread use of teicoplanin might accelerate the development of S. aureus resistance to both teicoplanin and vancomycin. The selection of an appropriate glycopeptide in an individual patient should be based not only on convenience, but also on a determination of optimal efficacy, safety at an efficacious dose, and the potential for resistance.