The safety and efficacy of linezolid in orthopaedic practice for the treatment of infection due to antibiotic-resistant organisms

Antibiotic therapy in reconstructive surgery of deep sternal wound infections

BACKGROUND

The choice of antibiotics and length of administration in the treatment of deep sternal wound infections (DSWI) is unclear. The reason for this is the lack of studies and local differences in resistance. An increase in resistance can be observed in gram-positive cocci, which are the most frequently detected in deep sternal infections. The duration of administration is often 2- 6 weeks or longer, although the benefit of prolonged antibiotic administration has not been confirmed by studies. We evaluated the antibiotic treatment during surgical treatment, consisting of surgical wound debridement and plastic chest reconstruction.

METHODS

Retrospective analysis of patients (n = 260) who underwent reconstructive surgery in the Department of Plastic Surgery at Leipzig University Hospital from 01.05.2012 - 31.12.2020. The duration of intake, results of microbiological swabs and resistance were investigated.

RESULTS

At the time of discharge, closed wound conditions were noted in 177 of 260 cases (68.1%). The largest proportion of patients (n = 238) was treated with a latissimus dorsi flap (91.5%).Antibiotic treatment was conducted in 206 of 260 cases (79.2%). The mean duration of antibiotic administration was 21.4 days (±17.6). Prolonged treatment over 14 days did not alter outcome (p = 0.226), in contrast, the number of multidrug resistances (p < 0.001). There was no prove of resistance against linezolid which is effective against the most common found infectious agents Staphylococcus epidermidis (n = 93; 24.0 %) & Staphylococcus aureus (n = 47; 12.1 %).

CONCLUSION

There is no evidence of benefit from antibiotic therapy over 14 days, whereas multidrug resistance increases with prolonged antibiotic use. In the absence of infectious agents or clinical signs of inflammation, surgical treatment without additional antibiotic treatment is effective.Linezolid is a suitable antibiotic in the treatment of gram-positive infections which are the most frequent in DSWI.

Prolonged use of linezolid in bone and joint infections: a retrospective analysis of adverse effects

OBJECTIVES

Antibiotic treatment for bone and joint infections generally lasts for 6 weeks or longer. Linezolid may be a good option for treating bone and joint infections, but there is an increased risk of potential serious adverse drug events (ADEs) when used for more than 28 days. The aim of this study was to obtain detailed information on the type and time to occurrence of the patient-reported ADEs, the dynamics of haematopoiesis over time, and the reasons for early discontinuation of linezolid when used for an intended maximum duration of 12 weeks.

METHODS

This single-centre retrospective study was conducted at the Sint Maartenskliniek in The Netherlands. Patients were included if they were planned to use linezolid for more than 28 days. The main reason for discontinuation of linezolid, the ADE according to the Naranjo score, and the time to occurrence of ADEs were analysed.

RESULTS

Among 78 patients, drug toxicity led to early discontinuation of linezolid in 11 (14%) patients before and nine (12%) after 28 days of therapy. The median treatment duration was 42 days. Gastrointestinal intolerance (42%) and malaise (32%) were the most common ADEs. In 75% of the cases the ADE occurred within 28 days of therapy. Sixty-seven patients were able to continue linezolid beyond 28 days, 87% of whom completed therapy as scheduled. Severe cytopenia, according to the Common Terminology Criteria for Adverse events (CTCA), was observed in four patients and was reversible after discontinuation of linezolid. One patient suffered optic neuropathy related to linezolid use.

CONCLUSIONS

Linezolid could be considered an alternative option to the current standard of IV glycopeptides for the treatment of bone and joint infection for up to 12 weeks. If patients pass the first 28 days of therapy, the likelihood of successful completion of therapy is high with a low risk of serious ADEs.

Zoliflodacin: An Oral Spiropyrimidinetrione Antibiotic for the Treatment of Neisseria gonorrheae, Including Multi-Drug-Resistant Isolates

The Centers for Disease Control and the World Health Organization have issued a list of priority pathogens for which there are dwindling therapeutic options, including antibiotic-resistant Neisseria gonorrheae, for which novel oral agents are urgently needed. Zoliflodacin, the first in a new class of antibacterial agents called the spiropyrimidinetriones, is being developed for the treatment of gonorrhea. It has a unique mode of inhibition against bacterial type II topoisomerases with binding sites in bacterial gyrase that are distinct from those of the fluoroquinolones. Zoliflodacin is bactericidal, with a low frequency of resistance and potent antibacterial activity against N. gonorrheae, including multi-drug-resistant strains (MICs ranging from ≤0.002 to 0.25 μg/mL). Although being developed for the treatment of gonorrhea, zoliflodacin also has activity against Gram-positive, fastidious Gram-negative, and atypical pathogens. A hollow-fiber infection model using S. aureus showed that that pharmacokinetic/pharmacodynamic index of fAUC/MIC best correlated with efficacy in in vivo neutropenic thigh models in mice. This data and unbound exposure magnitudes derived from the thigh models were subsequently utilized in a surrogate pathogen approach to establish dose ranges for clinical development with N. gonorrheae. In preclinical studies, a wide safety margin supported progression to phase 1 studies in healthy volunteers, which showed linear pharmacokinetics, good oral bioavailability, and no significant safety findings. In a phase 2 study, zoliflodacin was effective in treating gonococcal urogenital and rectal infections. In partnership with the Global Antibiotic Research Development Program (GARDP), zoliflodacin is currently being studied in a global phase 3 clinical trial. Zoliflodacin represents a promising new oral therapy for drug-resistant infections caused by N. gonorrheae.

Clinical and Microbiological Analysis of Deep Sternal Wound Infections in Fifty-Two Consecutive Patients

Background: Mediastinitis after cardiac surgery can lead to devastating consequences such as deep sternal wound infections (DSWI). Staphylococcus epidermidis and other coagulase-negative staphylococci belong to the physiological skin flora and therefore generally are not considered pathogenic agents. Thus, local resistance patterns of these bacterial species often recovered from wound specimens generally are ignored while choosing antibiotics for peri-operative prophylaxis in cardiac surgery as well as in the selection of empiric antibiotic therapy of DSWI. Methods: During the period May 2012-May 2013, 52 patients suffering from DSWI were treated at our institution. For every patient, deep tissue samples were obtained during surgical debridement procedures and submitted to microbiologic analysis. The frequency of and the time to occurrence of a DSWI was recorded, and baseline data, previous operative interventions, complications, and the technique used for soft tissue reconstruction, as well as the microbiologic results and individual risk factors, were documented. Results: There were 32 male patients (62%) and 20 female. The patients' age at the time of revision was a mean of 67 ± 11.5 years (range 35-83 years). There was bacterial growth in 31 cases (60%), the predominant species being S. epidermidis (20 patients; 65%). Extended antibiotic therapy was indispensable to controlling the infection. Conclusion: The local resistance patterns of antibiotics should have a greater influence on the standardized prophylaxis or empirical therapy of DSWI and need to be discussed specifically for this high-risk population. Because of its multi-resistance spectrum, S. epidermidis must be classified as a potential pathogen. In the cases reported here, extended antibiotic therapy was necessary to support wound healing and thus good patient outcomes.

Responding to the challenge of untreatable gonorrhea: ETX0914, a first-in-class agent with a distinct mechanism-of-action against bacterial Type II topoisomerases

With the diminishing effectiveness of current antibacterial therapies, it is critically important to discover agents that operate by a mechanism that circumvents existing resistance. ETX0914, the first of a new class of antibacterial agent targeted for the treatment of gonorrhea, operates by a novel mode-of-inhibition against bacterial type II topoisomerases. Incorporating an oxazolidinone on the scaffold mitigated toxicological issues often seen with topoisomerase inhibitors. Organisms resistant to other topoisomerase inhibitors were not cross-resistant with ETX0914 nor were spontaneous resistant mutants to ETX0914 cross-resistant with other topoisomerase inhibitor classes, including the widely used fluoroquinolone class. Preclinical evaluation of ETX0914 pharmacokinetics and pharmacodynamics showed distribution into vascular tissues and efficacy in a murine Staphylococcus aureus infection model that served as a surrogate for predicting efficacious exposures for the treatment of Neisseria gonorrhoeae infections. A wide safety margin to the efficacious exposure in toxicological evaluations supported progression to Phase 1. Dosing ETX0914 in human volunteers showed sufficient exposure and minimal adverse effects to expect a highly efficacious anti-gonorrhea therapy.

Clinical results of linezolid in arthroplasty and trauma MRSA related infections

AIM: To analyse the management of patients treated with linezolid for orthopaedic infections.

METHODS: Twenty-two patients with orthopaedic related infections receiving a course of linezolid were reviewed retrospectively. Patients were classified into either post trauma, post arthroplasty and non trauma related infections. A diagnosis of infection was based on clinical findings, positive microbiological specimens, and positive signs of infection on radiological imaging and raised inflammatory markers. Pathogens isolated, inflammatory markers both at presentation and at final follow up, length of linezolid treatment, adverse drug reactions, concomitant anti-microbial therapy, length of hospital stay and any surgical interventions were recorded.

RESULTS: Infections were classified as post arthroplasty (n = 10), post trauma surgery (n = 8) or non-trauma related infections (n = 4). Twenty patients (91%) underwent surgical intervention as part of their treatment. The number of required surgical procedures ranged from 1 to 6 (mean = 2.56). Mean total length of stay per admission was 28.5 d (range 1-160 d). Furthermore, the mean duration of treatment with linezolid of patients who had resolution of symptoms was 31 d (range 10-84 d). All patients within this group were discharged on oral linezolid. Pathogens isolated included methicillin resistant Staphylococcus aureus, coagulase negative staphylococci, coliforms, enterococcus, Staphylococcus epidermidis, streptococcus viridans, Escherichia coli, group B streptococcus and pseudomonas. An overall 77% of patients demonstrated resolution of infections at follow-up, with mean C-reactive protein reducing from 123 mg/L to 13.2 mg/L.

CONCLUSION: This study demonstrates that the use of linezolid offers excellent efficacy in orthopaedic related infections when used alongside appropriate surgical management.

Implant stability in the treatment of MRSA bone implant infections with linezolid versus vancomycin in a rabbit model

The increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infections represents a significant healthcare burden. Vancomycin and linezolid exhibit potent clinical and microbiological activity in MRSA infections. Our purpose was to investigate the efficacy of linezolid versus vancomycin in experimental implant infections and the influence on implant stability in a rabbit model. Thirty-six female New Zealand White rabbits received surgical insertion of titanium implants into their distal femurs and were randomly assigned to six groups (A: infected, no treatment; B: infected, vancomycin; C: infected, linezolid; D: no infection, no treatment; E/F: no infection, vancomycin or linezolid, respectively). Antibiotics were administered, and plasma levels determined. Bone-implant specimens were tested for mechanical stability of fixation. Quantitative histomorphometry of bone and soft tissue was performed using computerized image analysis. Plasma levels of linezolid and vancomycin were within the respective therapeutic ranges. Microbiological analysis of specimens from infected rabbits showed MRSA tissue colonization in all untreated animals, in two of six vancomycin-treated animals, and in none of the linezolid-treated animals. Antibiotic treatment improved mechanical stability significantly (p = 0.004) with both vancomycin and linezolid. Mechanical testing correlated with histomorphometry results. A significant negative correlation was found between displacement of the implant and the percentage of calcified tissue around the implant, and a significant positive correlation was found between displacement of the implant and the amount of noncalcified tissue. Our data indicate that both treatment regimens improved implant stability.

Efficacies of ceftobiprole medocaril and comparators in a rabbit model of osteomyelitis due to methicillin-resistant Staphylococcus aureus

The pharmacokinetics and distribution into bone tissue of ceftobiprole in uninfected New Zealand White rabbits were determined after subcutaneous administration of the prodrug ceftobiprole medocaril. Serum exposure (maximum concentration of the drug in serum, trough concentration, area under the concentration-time curve) to ceftobiprole at 20 and 80 mg/kg was dose proportional, and there was no accumulation of ceftobiprole following repeated (every 6 h [q6h]) injections of the antibiotic. Ceftobiprole titers in the tibial matrix and marrow were 3.2 +/- 1.3 microg/g and 11.2 +/- 6.5 microg/g, respectively, in uninfected animals treated with 20 mg/kg of the antibiotic and 13.4 +/- 7.3 microg/g and 66.3 +/- 43.2 microg/g, respectively, in uninfected animals treated with 80 mg/kg of the antibiotic. No differences in ceftobiprole titers were observed between right and left tibiae for either bone matrix or marrow. The efficacies of 4 weeks of treatment with ceftobiprole (40 mg/kg administered subcutaneously [s.c.] q6h), vancomycin (30 mg/kg administered s.c. q12h), or linezolid (60 mg/kg administered orally q8h) were compared, using a rabbit model of methicillin-resistant Staphylococcus aureus tibial osteomyelitis. After treatment with ceftobiprole, the bacterial titers in all infected left tibiae from evaluable rabbits were below the level of detection, whereas only 73% of infected left tibiae from vancomycin- or linezolid-treated animals had bacterial titers below the level of detection; the mean titers of ceftobiprole were 3 to 5 times higher in infected left tibiae than in uninfected right tibiae. These results indicate that ceftobiprole provided effective parenteral treatment of osteomyelitis in this rabbit model.

Treatment of orthopedic infections caused by resistant staphylococci

During 1999-2005 we treated 15 patients with linezolid for relevant infections of locomotion apparatus (7 cases with endoprosthesis infection, 5x osteomyelitis and 3x another infection). With the exception of one case the antibiotic therapy was always combined with appropriate surgical intervention. Average period of linezolid administration was 26 d; linezolid was applied from the beginning intravenously on average for 10 d, and then orally for 16 d (average). There were no undesirable effects in the file. Success rate reached 86.6%. MRSA strains were proved by standard methods: growth on Mueller-Hinton agar with increased concentration of NaCl and 2 mg/L of oxacilline, and measuring inhibitory zones around cephoxitine disk. The sensitivity to other antibiotics was specified by disk-diffusion test; that to linezolid was verified by E-test. Linezolid represents a medical reserve for the treatment of multiresistant Gram-positive infections or for emergencies, when allergy onset, high toxicity risk, intolerance, etc. do not allow to use other, in vitro effective, antibiotics.

Linezolid in the treatment of implant-related chronic osteomyelitis

New antibiotics have been developed targeting resistant microorganisms; however, limited information is available on their use in implant-related chronic osteomyelitis. We evaluated the infection control rate of linezolid in treating these challenging infections and delineate indications for its use. We retrospectively reviewed 22 consecutive adult patients with chronic implant-related osteomyelitis, treated with linezolid in addition to surgical débridement and implant removal. Osteomyelitis was associated with fracture fixation implants (n = 18) or arthroplasty implants (n = 4). Methicillin-resistant Staphylococcus aureus (MRSA) was the most common pathogen (10 of 22 patients). Fourteen patients had one or more comorbidity, including intravenous drug abuse in four patients. Indications for linezolid use included preference for oral administration in 13 patients, presence of vancomycin-resistant enterococcus (VRE) in five patients, and development of allergic reactions to vancomycin in four patients. Fourteen patients were followed for a minimum of 6 months (mean, 22 months; range, 6-34 months) with no recurrence of infection. Linezolid is a reasonable alternative for treating chronic implant-related osteomyelitis. Our treatment protocol, including linezolid, achieved control of infection in all patients despite the challenging nature of these infections due to patient comorbidities and resistant organisms.

New carbon-linked azole oxazolidinones with improved potency and pharmacokinetics

Substitution of phenyl oxazolidinones with carbon-linked azoles resulted in the discovery of a new class of potent oxazolidinones that have excellent Gram-positive activity. In addition, replacement of the C-5 acetamide side chains with a 4-methyl triazole diminished monoamine oxidase activity. The synthesis and biological evaluation of these compounds are reported.

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.

[Clinically significant toxicity and tolerance of the main antibiotics used in lower respiratory tract infections]

The purpose of this article was not to review all reported adverse reactions of antibiotics used in the treatment of lower respiratory tract infections but rather to focus either on those which might have an impact on observance, efficacy, and resistance, or on rare but life-threatening adverse effects such as torsade de pointe. The latter are mostly predictable and prescribers should adhere to precautions and contraindications. For new antibiotics, the number of patients enrolled in phase I to III clinical trials is far to small to detect such rare adverse effects and large post registration tolerance surveys are mandatory. ss-lactams are well tolerated. The risk of anaphylactic reaction is magnified by patient reports and can be reduced by skin testing. Macrolides are well tolerated as well. The risk of cardiac toxicity should be reduced by assessing individual susceptibility and avoiding drug interactions. The tolerance to telithromycin, a new ketolide, is similar to that of macrolides. Serious toxic reactions such as convulsions, tendon rupture, torsade de pointe, and hypoglycemia are associated with the use of fluoroquinolones. Most of these adverse reactions can be often circumvented by avoiding exposure patients at risk. Quinupristin/dalfopristin can induce arthralgia and myalgia and the major adverse effects of linezolid are IMAO like reactions, reversible myelosuppression, and peripheral neuropathy. Most of the adverse antibiotic reactions are reported when precautions of use in susceptible patients are not taken into account. When they are, the safety/risk ratio is good.

Severe staphylococcal knee arthritis responding favourably to linezolid, after glycopeptide-rifampicin failure: a case report and literature review

A puzzling case report of a septicaemic post-surgical staphylococcal knee arthritis which did not respond to long-term courses of associated rifampicin and teicoplanin or vancomycin, despite apparently favourable in vitro susceptibility assays, but which rapidly resolved after i.v. followed by oral administration of linezolid is presented, and discussed in the context of the most recent literature evidence. The lack of response to a 14-d-long course of glycopeptides does not find explanation from the in vitro minimum inhibitory concentrations (MIC90) of involved organisms, which showed full susceptibility of Staphylococcus aureus to vancomycin and teicoplanin, and sensitivity of an accompanying Staphylococcus epidermidis isolated from blood cultures to vancomycin and rifampicin, with borderline 'intermediate' values found for teicoplanin. Since neither bone involvement nor abscess formation was of concern, effective glycopeptide and rifampicin penetration into infectious tissue should have been assured. From a clinical viewpoint, the introduction of a 2-week i.v. linezolid followed by 1 further week of oral linezolid led to complete clinical and microbiological cure, and an unexpected functional success.