Intravenous Cefazolin Achieves Sustained High Interstitial Concentrations in Open Lower Extremity Fractures

BACKGROUND

Infection remains a serious clinical concern in patients with open fractures, despite timely antibiotic administration and surgical debridement. Soft tissue and periosteal stripping may alter local tissue homeostasis and antibiotic pharmacokinetics in the injured limb. The tissue (interstitial) concentration of intravenously administered antibiotics at an open fracture site has not been characterized using direct sampling techniques.

QUESTION/PURPOSE

We performed this study to evaluate the concentration and pharmacokinetics of intravenously delivered cefazolin at an open fracture site after surgical debridement.

METHODS

Twelve patients with an open fracture distal to the knee who presented at a regional Level I trauma center were approached for enrollment in this nonrandomized, observational study. Of the 12 patients, eight adults (one female, seven male) with a median age of 32 years (range 23 to 51 years) were enrolled and underwent successful sample collection for analysis. Three patients had incomplete datasets because of equipment malfunction and one elected not to participate. Seven patients had open tibia fractures, and one patient had an open fibula fracture associated with a closed tibia fracture. There were six Gustilo-Anderson Type II injuries and two Type IIIA injuries. Empiric antibiotics were administered in the prehospital setting or in the emergency department according to institutional protocol. When patients were taken to the operating room, a 2-g intravenous dose of cefazolin was administered. After surgical debridement, fracture stabilization, and wound closure, a microdialysis catheter was placed transdermally into the injury zone (within 5 cm of the fracture site) and a second catheter was placed in the contralateral uninjured (control) limb. Additional doses of cefazolin were administered every 8 hours postoperatively. Baseline and periodic interstitial fluid and whole blood (plasma) samples were collected in the operating room and at prespecified times for 24 hours postoperatively. Free cefazolin in the interstitial fluid and plasma samples were analyzed by ultra-high-performance liquid chromatography using C 18 column separation with quadrupole time-of-flight mass spectrometry detection. Data from the second postoperative dose of cefazolin were used to characterize pharmacokinetic parameters through a noncompartmental analysis using time-concentration curves of free cefazolin and assuming first-order elimination. For pharmacodynamic analyses, the modal cefazolin minimum inhibitory concentration (MIC) of Staphylococcus aureus (1 µg/mL) was used.

RESULTS

With the samples available, no difference was observed in the median free cefazolin exposure over 24 hours ( f area under the curve [AUC] 0→24hrs ) between injured limbs (352 μg∙hr/mL [IQR 284 to 594 μg∙hr/mL]) and uninjured limbs (341 μg∙hr/mL [IQR 263 to 438 μg∙hr/mL]; p = 0.64). The median time to achieve the maximum concentration of free cefazolin ( f T max ) for injured limbs was delayed (2.7 hours [IQR 2.2 to 3.1 hours]) compared with control limbs (1.7 hours [IQR 1.2 to 2.0 hours]; p = 0.046). The time to the maximum concentration for plasma was not different from that of control limbs (p = 0.08). The time the cefazolin concentration was above the modal S. aureus MIC (T > MIC) in the injured and control limbs over 24 hours was 100% (IQR 100% to 100%) and 100% (IQR 97% to 100%), respectively.

CONCLUSION

These preliminary findings suggest that current prophylactic cefazolin dosing regimens result in successful antibiotic delivery to the traumatized limb in moderately severe open fractures. Although cefazolin delivery to open-fracture wound beds was delayed compared with healthy tissues, the cefazolin concentration was sustained above the European Union Committee Antimicrobial Susceptibility Testing modal MIC for S. aureus , demonstrating a high likelihood of a prophylactic antimicrobial environment at an open fracture site with this empiric antimicrobial regimen. Importantly, patients in this analysis had Gustilo-Anderson Types II and IIIA injuries. Further research with a larger patient cohort is needed to determine whether antibiotic delivery to traumatized soft tissues in patients with higher-grade open fractures (Gustilo-Anderson Types IIIB and IIIC) demonstrates similar pharmacokinetic characteristics.

LEVEL OF EVIDENCE

Level II, therapeutic study.

External validation of a pharmacokinetic model for target-controlled infusion of cefazolin as a prophylactic antibiotic

AIMS

This study aimed to evaluate the predictive performance of previously constructed cefazolin pharmacokinetic models and determine whether cefazolin administration via the target-controlled infusion (TCI) method may be possible in clinical practice.

METHODS

Twenty-five gastrectomy patients receiving cefazolin as a prophylactic antibiotic were enrolled. Two grams of cefazolin was dissolved in 50 mL of normal saline to give a concentration of 40 mg mL-1 . Before skin incision, cefazolin was administered using a TCI syringe pump, and its administration continued until the end of surgery. The target total plasma concentration was set to 100 μg mL-1 . Total and unbound plasma concentrations of cefazolin were measured in three arterial blood samples collected at 30, 60 and 120 min after the start of cefazolin administration. The predictive performance of the TCI system was evaluated using four measures: inaccuracy, divergence, bias and wobble.

RESULTS

Total (n = 75) and unbound (n = 75) plasma concentration measurements from 25 patients were included in the analysis. The pooled median (95% confidence interval) biases and inaccuracies were 6.3 (4.0-8.5) and 10.5 (8.6-12.4) for the total concentration model and -10.3 (-16.8 to -3.7) and 22.4 (18.2-26.7) for the unbound concentration model, respectively. All unbound concentrations were above 10 μg mL-1 .

CONCLUSION

Administration of cefazolin by the TCI method showed a clinically acceptable performance. Applying the TCI method by setting the total concentration as the target concentration rather than the unbound concentration is effective in maintaining a constant target concentration of cefazolin.

Oral antimicrobial therapy for cellulitis versus outpatient parenteral antimicrobial therapy: a single-centre audit of cellulitis outcomes

BACKGROUND

Cellulitis is a common acute skin and soft tissue infection that causes substantial morbidity and healthcare costs.

AIMS

To audit the impact on cellulitis management, regimen tolerability and outcomes of switching from outpatient parenteral antimicrobial therapy (OPAT) using intravenous (i.v.) cefazolin once daily plus probenecid to oral beta-lactam therapy (OBLT) using oral flucloxacillin plus probenecid.

METHODS

We undertook a retrospective audit on cellulitis management, regimen tolerability and outcomes at the Dunedin Public Hospital Emergency Department (ED) before and after a change of the local outpatient cellulitis treatment pathway from OPAT using i.v. cefazolin once daily plus probenecid to OBLT using oral flucloxacillin plus probenecid.

RESULTS

OPAT was used in 97/123 (78.9%) patients with cellulitis before compared to 1/70 (1.4%) after the pathway change (odds ratio (OR), 0.04, P < 0.01). OBLT was used in 26/123 (21.1%) patients with cellulitis before and 69/70 (98.6%) after (OR, 218.8, P < 0.01). Antimicrobial change due to intolerance occurred in 4/123 (3.2%) patients with cellulitis before and 4/70 (5.7%) after (OR, 1.8, P, not significant (NS)) the pathway change. Inpatient admission within 28 days occurred in 15/123 (12.2%) cellulitis patients before and 9/70 (12.9%) after (OR, 1.1, P, NS) the pathway change.

CONCLUSIONS

Implementation of a change in outpatient cellulitis treatment pathway resulted in a significant change in prescribing practice. Our findings suggest that OBLT was both tolerable and had similar outcomes to OPAT.

The role of clinical pharmacists in patients with suspected allergy to β-lactams: A systematic review

OBJECTIVE

To analyze the role played by the clinical pharmacist and its impact in antibiotic stewardship facing suspected allergy to beta-lactam antibiotics.

METHOD

We performed two different independent bibliographic searches. A total of 35 articles were found, and the final number included in the study was 12. We analysed the articles and collected variables of efficacy, safety and applicability of evaluation tools applied to patients with suspected allergy to beta-lactams. Also, the variation in the consumption and prescription profile of alternative antibiotics was analyzed.

RESULTS

The selected studies analysed questionnaires, allergy delabeling, intradermal tests and oral challenge tests performed by pharmacists. Significant differences in the efficacy endpoint were found in 4 studies in favour of pharmaceutical intervention. In the study of Kwiatkowski et al, cefazolin use increased in surgical patients after pharmacist intervention (65 vs. 28%; p < 0.01). In a quasi-experimental study, the mean defined daily dose of aztreonam and the mean days of therapy per 1000 patients/day decreased (21.23 vs 9.05, p <0.01) and (8.79-4.24, p = 0.016), pre and post-intervention, respectively, increasing antibiotic de-escalations (p ≤ 0.01). In another quasi-experimental study, the prescription of restricted-use antibiotics decreased (42.5% vs. 17.9%, p < 0.01) and the use of pre-surgical prophylactic antibiotics alternative to cefazolin (81.9% vs 55.9%, p<0.01) in another study. Other study showed that the mean time per interview was 5.2 minutes per patient. No adverse events were reported in any study.

CONCLUSION

The pharmacist intervention in the evaluation of the patient with suspected allergy to beta-lactams is effective, safe and feasible to implement on daily clinical practice. The standardization of protocols to clarify the history of allergies and development of evaluation tools represent simple screenings to perform delabelling or refer to the Immunoallergology service, improving penicilins use and reducing the need for second line antibiotics. More studies are needed to standardize the desensitization tests made by pharmacists. However, despite these results, the involvement and leadership of the pharmacist in this area is limited and constitutes a future challenge for the profession.

[Translated article] The role of clinical pharmacists in patients with suspected allergy to β-lactams: A systematic review

OBJECTIVE

To analyze the role played by the clinical pharmacist and its impact in antibiotic stewardship facing suspected allergy to beta-lactam antibiotics.

METHOD

We performed 2 different independent bibliographic searches. A total of 35 articles were found, and the final number included in the study was 12. We analyzed the articles and collected variables of efficacy, safety, and applicability of evaluation tools applied to patients with suspected allergy to beta-lactams. Also, the variation in the consumption and prescription profile of alternative antibiotics was analyzed.

RESULTS

The selected studies analyzed questionnaires, allergy delabeling, intradermal tests, and oral challenge tests performed by pharmacists. Significant differences in the efficacy endpoint were found in 4 studies in favor of pharmaceutical intervention. In the study of Kwiatkowski et al., cefazolin use increased in surgical patients after pharmacist intervention (65% vs 28%; P < .01). In a quasi-experimental study, the mean defined daily dose of aztreonam and the mean days of therapy per 1000 patients/day decreased (21.23 vs 9.05, P <.01) and (8.79-4.24, P = .016), pre- and post-intervention, respectively, increasing antibiotic de-escalations (P = < .01). In another quasi-experimental study, the prescription of restricted use antibiotics decreased (42.5% vs 17.9%, P < .01)and the use of pre-surgical prophylactic antibiotics alternative to cefazolin (81.9% vs 55.9%, P < .01)in another study. Other study showed that the mean time per interview was 5.2 min per patient. No adverse events were reported in any study.

CONCLUSION

The pharmacist intervention in the evaluation of the patient with suspected allergy to beta-lactams is effective, safe, and feasible to implement on daily clinical practice. The standardization of protocols to clarify the history of allergies and development of evaluation tools represent simple screenings to perform delabeling or refer to the Immunoallergology service, improving penicilins use and reducing the need for second-line antibiotics. More studies are needed to standardize the desensitization tests made by pharmacists. However, despite these results, the involvement and leadership of the pharmacist in this area is limited and constitutes a future challenge for the profession.

Anaphylaxis mortality in the perioperative setting: Epidemiology, elicitors, risk factors and knowledge gaps

Perioperative anaphylaxis (PA) is a severe condition that can be fatal, but data on PA mortality are scarce. The aim of this article is to review the epidemiology, elicitors and risk factors for PA mortality and identify knowledge gaps and areas for improvement regarding the management of severe PA. PA affects about 100 cases per million procedures. Mortality is rare, estimated at 3 to 5 cases per million procedures, but the PA mortality rate is higher than for other anaphylaxis aetiologies, at 1.4% to 4.8%. However, the data are incomplete. Published data mention neuromuscular blocking agents and antibiotics, mainly penicillin and cefazolin, as the main causes of fatal PA. Reported risk factors for fatal PA vary in different countries. Most frequently occurring comorbidities are obesity, male gender, cardiovascular diseases and ongoing treatment with beta-blockers. However, there are no clues about how these factors interact and the impact of individual risk factors. The pathophysiology of fatal PA is still not completely known. Genetic factors such as deficiency in PAF-acetyl hydrolase and hereditary alpha-tryptasemia, have been reported as modulators of severe anaphylaxis and possible targets for specific treatments. Our review underlines unmet needs in the field of fatal PA. Although we confirmed the need for timely administration of an adequate dose of adrenaline and the proper infusion of fluids, there is no evidence-based data on the proper dose of intravenous titrated adrenaline and which clinical manifestations would flag the need for fluid therapy. There are no large clinical studies supporting the administration of alternative vasopressors, such as glucagon and methylene blue. Further research on pathophysiological mechanisms of PA and its severity may address these issues and help clinicians to define new therapeutic approaches.

Indication-driven order entry decreases stewardship and pharmacist interventions

Indication-driven order entry (IDOE) was implemented at our pediatric institution for cefazolin, piperacillin-tazobactam, and meropenem; the 3 most intervened upon antibiotics during prospective audit and feedback (PAF) by the antimicrobial stewardship program (ASP). IDOE was associated with a significant reduction in both ASP PAF recommendations and clinical pharmacist interventions.

Pharmacokinetic analysis of ceftazidime and cefazolin in the treatment of continuous ambulatory peritoneal dialysis-related peritonitis

OBJECTIVE

Peritoneal dialysis-related peritonitis (PDRP) presents a significant challenge for nephrologists. Continuous intraperitoneal cefazolin and ceftazidime are recommended for the treatment of peritonitis. However, some pharmacokinetic studies have shown that doses of 15-20 mg/kg/d may not achieve sufficient therapeutic levels. In this study, we investigated the pharmacokinetics of ceftazidime and cefazolin in patients with continuous ambulatory peritoneal dialysis-related peritonitis and compared the pharmacokinetic characteristics between traditional and modified treatment groups.

METHODS

From February 2017 to December 2019, 42 PDRP patients (17 males, 25 females; mean age: 50.7 ± 12.1 years; mean body weight: 60.9 ± 11.8 kg) were recruited for the study, all participants were anuric. Twenty patients were enrolled in the traditional group and treated with cefazolin (1.0 g) and ceftazidime (1.0 g) via intraperitoneal administration once daily for 14 days. Twenty-two patients were enrolled in the modified group and received the same dose of antibiotics twice daily for the initial five days, followed by once daily for the subsequent nine days. Serum and dialysate samples were collected after days 1, 2, 3, 5, 7, 10, and 14 and analyzed via liquid chromatography-mass spectrometry.

RESULTS

In the traditional group, the highest and lowest serum concentrations of ceftazidime were 35.9 and 21.7 µg/mL, respectively. The highest concentration of cefazolin was 54.6 µg/mL on day 5 and the lowest concentration was 30.4 µg/mL on day 1. In the modified group, the highest and lowest serum concentrations of ceftazidime were 102.2 and 54.8 µg/mL, respectively. The highest concentration of cefazolin was 141.7 µg/mL and the lowest concentration was 79.8 µg/mL. All antibiotic concentrations were above the minimum inhibitory concentration (MIC) level (8 µg/mL of ceftazidime and 2 µg/mL of cefazolin) throughout the treatment period. However, on day 1, the concentration of ceftazidime in the third bag of dialysate effluent from the traditional group fell below the MIC level. Despite remaining above the MIC, cefazolin concentration was consistently lower in the third bag of dialysate effluent from the traditional group throughout the treatment period.

CONCLUSIONS

Intraperitoneal administration of cefazolin and ceftazidime at a dose of 1 g twice daily for 5 days and then once daily for the rest of the treatment period ensured adequate therapeutic levels of antibiotics for treating anuric PDRP patients.

Empiric antibiotic treatment for periprosthetic joint infections: a national survey in The Netherlands

Early periprosthetic joint infection (PJI) is generally treated by means of debridement, antibiotics and implant retention (DAIR). Subsequently, empiric antibiotic therapy is commenced directly after surgery which is important for the successful treatment of PJI. The aim of this study is to evaluate current nationwide empiric antibiotic treatment regimens for PJI in the Netherlands. An electronic 15-question survey addressing the empiric antibiotic treatment strategy for PJI following THA or TKA was sent to orthopaedic surgeons in all Dutch hospitals in April 2019. Orthopaedic surgeons active in every single Dutch orthopaedic hospital (n=69) were approached. At least one surgeon in every hospital completed the survey (100% response rate). A protocol dictating the empiric antibiotic treatment following DAIR was used in 87% (60 hospitals). Among all hospitals, 72% (50 hospitals) used antibiotic monotherapy and 28% (19 hospitals) used combination therapy. Cefazolin was the most commonly used regimen in centres opting for monotherapy (42%, 29 hospitals). Similar regimens were used for the empiric treatment of suspected early PJI after revision surgery and for acute hematogenous PJI. In septic patients, combination therapy was preferred (64%). 81% (56 hospitals) incubated tissue biopsies for a minimum of 10 days whereas 16% (9 hospitals) indicated an incubation period of 7 days or less. Even in a small country such as the Netherlands there seems to be no uniformity regarding empiric antibiotic treatment for PJI. Increased uniformity regarding empiric treatment could be an important first step in improving PJI treatment.

Comparison of prophylactic antibiotics for endonasal transsphenoidal surgery using a national inpatient database in Japan

BACKGROUND

The choice of prophylactic antibiotics for use in endonasal transsphenoidal surgery (ETSS) lacks universal standards. This study aimed to investigate the effectiveness of cefazolin, ampicillin and third-generation cephalosporins for preventing postoperative meningitis and secondary outcomes (in-hospital death and the combination of pneumonia and urinary tract infection) in patients who have undergone ETSS.

METHODS

The study used data from the Diagnosis Procedure Combination database in Japan. Data from 10 688 patients who underwent ETSS between April 2016 and March 2021 were included. Matching weight analysis based on propensity scores was conducted to compare the outcomes of patients receiving cefazolin, ampicillin or third-generation cephalosporins as prophylactic antibiotics.

RESULTS

Of the 10 688 patients, 9013, 102 and 1573 received cefazolin, ampicillin and third-generation cephalosporins, respectively. The incidence of postoperative meningitis did not significantly differ between the cefazolin group and the ampicillin group (OR, 1.02; 95% CI, 0.14-7.43) or third-generation cephalosporins group (OR, 0.81; 95% CI, 0.10-6.44). Similarly, in-hospital death and the composite incidence of pneumonia and urinary tract infection did not differ between the cefazolin group and the ampicillin or third-generation cephalosporins group.

CONCLUSIONS

Cefazolin, ampicillin and third-generation cephalosporins as perioperative prophylactic antibiotics for ETSS do not differ significantly in terms of preventing meningitis.

Therapeutic Options for Adult Patients With Persistent Methicillin-Susceptible Staphylococcus aureus Bacteremia: A Narrative Review

OBJECTIVE

To compare the efficacy of antimicrobial therapies used in the management of persistent methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia.

DATA SOURCES

A literature search using the PubMed database (inception to December 2022) was conducted using the search terms "Staphylococcus aureus bacteremia," "methicillin-susceptible Staphylococcus aureus bacteremia," "persistent methicillin-susceptible Staphylococcus aureus bacteremia," and "refractory methicillin-susceptible Staphylococcus aureus bacteremia ." In addition, therapeutic agents which could be used as treatment for MSSA including "nafcillin," "oxacillin," "cefazolin," "ceftaroline," "gentamicin," "rifampin," and "daptomycin" were also combined with the aforementioned search terms to capture data using these agents.

STUDY SELECTION/DATA EXTRACTION

Clinical data were limited to those published in the English language. Articles and abstracts were considered for inclusion in addition to ongoing trials identified through ClinicalTrials.gov.

DATA SYNTHESIS

A total of 78 articles were reviewed including 17 in vitro or animal model studies and 39 studies including patient data. The remaining 22 articles included guidelines, review articles, and editorials. Recent data evaluating use of dual β-lactam regimens for persistent MSSA bacteremia were limited to 8 case reports or case series.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

At present, there is little guidance on how to best manage patients with persistent MSSA bacteremia. This narrative review collates the available data to assist clinicians in selecting the best possible antimicrobial regimen when facing this clinical conundrum.

CONCLUSIONS

Modification of antimicrobial therapy, in conjunction with source control and infectious diseases consultation, may all be necessary to sterilize blood cultures in patients with persistent MSSA bacteremia.

Rat model of recalcitrant prosthetic joint infection using biofilm inocula

Prosthetic joint infection (PJI) is a rare but devastating complication of joint arthroplasty. Biofilm formation around the prosthesis confers tolerance to antibiotics so that treatment is challenging. Most animal models of PJI use planktonic bacteria to establish the infection which fails to reproduce the pathology of chronic infection. We aimed to establish a rat model of Staphylococcus aureus PJI in male Sprague-Dawley rats using biofilm inocula and demonstrate its tolerance to frontline antibiotics. Pilot studies indicated that infection could be introduced to the knee joint by a biofilm-coated pin but that handling the prosthetic without disturbing the biofilm was difficult. We, therefore, developed a pin with a slotted end and used a miniature-biofilm reactor to develop mature biofilm in this niche. These biofilm-laden pins consistently produced infection of the bone and joint space. Treatment with high dose cefazolin, 250 mg/kg, starting the day of surgery reduced or cleared pin-adherent bioburden within 7 days, however when escalation from 25 to 250 mg/kg cefazolin treatment was delayed for 48 h, rats were unable to clear the infection. To track infections, we used bioluminescent bacteria, however, the bioluminescent signal did not accurately track the degree of infection in the bone and joint space as the signal did not penetrate the bone. In conclusion, we demonstrate that using a custom prosthetic pin, we can generate biofilm in a specific niche using a novel bioreactor setup and initiate a rat PJI that rapidly develops tolerance to supra-clinical doses of cefazolin.

In Vitro Characterization of Drug-Loaded Superabsorbent Polymer Microspheres: Absorption and Release Capacity of Contrast Material, Antibiotics and Analgesics

PURPOSE

To examine the characteristics of drug-loaded superabsorbent polymer microspheres (SAP-MS) such as drug absorption, drug release, diameter, and visibility.

MATERIALS AND METHODS

SAP-MS (HepaSphere150-200 µm; Merit Medical, South Jordan, UT, USA) were suspended in drug solutions: (a) cefazolin, (b) lidocaine, (c) iopamidol and cefazolin, (d) iopamidol and lidocaine, and (e) iopamidol, cefazolin, and lidocaine. The concentrations of drugs were measured, and the amount of each drug absorbed was calculated. Filtered drug-loaded SAP-MS were mixed with saline, and the drug release rates were calculated. The diameter changes of SAP-MS during absorption were observed. Radiography of drug-loaded SAP-MS was evaluated as radiopacity by contrast-to-noise ratio (CNR).

RESULTS

The drug concentration did not change during absorption. The release rates increased for 10 min and then came to an equilibrium. The mean amounts of drug absorbed at 180 min and mean release rates at 24 h were (a) cefazolin: 265.4 mg, 64.2%; (b) lidocaine: 19.6 mg, 75.6%; (c) iopamidol: 830.2 mg, 22.5%; cefazolin: 137.6 mg, 21.2%; (d) iopamidol: 1620.6 mg, 78.5%; lidocaine: 13.5 mg, 81.4%; and (e) iopamidol: 643.7 mg, 52.9%; cefazolin: 194.0 mg, 51.6%; lidocaine: 5.3 mg, 58.4%. The diameter of SAP-MS increased for approximately 15 min. Finally, the diameters of SAP-MS were (a) 3.9 times, (b) 5.0 times, (c) 2.2 times, (d) 5.5 times, and (e) 3.6 times larger than the original size. Drug-loaded SAP-MS containing iopamidol were visible under X-ray imaging, with CNRs of (c) 3.0, (d) 9.0, and (e) 4.5.

CONCLUSION

SAP-MS can absorb and release iopamidol, cefazolin, and lidocaine.

Treatment outcomes with benzylpenicillin and non-benzylpenicillin antibiotics, and the performance of the penicillin zone-edge test versus molecular detection of blaZ in penicillin-susceptible Staphylococcus aureus (PSSA) bacteraemia

OBJECTIVES

The blaZ gene encodes penicillinase, which inactivates penicillin. As there were reports on suboptimal sensitivity for the penicillin zone-edge test, a phenotypic method for blaZ detection, we investigated treatment outcomes in patients with penicillin-susceptible Staphylococcus aureus (PSSA) bacteraemia (phenotypically negative for penicillinase), subjecting isolates to molecular testing for blaZ retrospectively.

PATIENTS AND METHODS

A retrospective cohort study was conducted on 121 patients with a first episode of PSSA bacteraemia from 1 January 2012 to 31 October 2015 at Tan Tock Seng Hospital (TTSH), Singapore. Patients were grouped into IV benzylpenicillin and non-benzylpenicillin groups. The primary outcome was overall treatment failure, defined as either 30 day all-cause mortality and/or 90 day relapse. The penicillin (P10) zone-edge test was repeated on archived PSSA isolates, concurrently with penicillin MIC determination via gradient diffusion and PCR for blaZ.

RESULTS

Among 121 patients, 57 patients (47.1%) received IV benzylpenicillin as the predominant antibiotic. There was no significant difference in overall treatment failure between treatment with the benzylpenicillin [7/57 (12.3%)] versus non-benzylpenicillin groups [12/64 (18.8%)] (P = 0.33) or cloxacillin/cefazolin [6/37 (16.2%)] (P = 0.59). For 112 PSSA isolates available for testing, repeat penicillin zone-edge testing was negative for penicillinase production, corroborating previous results. A single PSSA isolate with a negative penicillin zone-edge test was found to be positive for blaZ.

CONCLUSIONS

We found no differences in overall treatment failure between patients with PSSA bacteraemia treated with benzylpenicillin, anti-staphylococcal β-lactams cefazolin/cloxacillin and other antimicrobials, when using the penicillin zone-edge test as the phenotypic method for blaZ screening.

Optimal drug therapy for Staphylococcus aureus bacteraemia in adults

PURPOSE OF REVIEW

Staphylococcus aureus is a significant human pathogen, causing a variety of infections, from skin and soft tissue infections to endocarditis, bone and joint infections and deep tissue abscesses. Mortality from S. aureus bacteraemia remains high, without major therapeutic advances in recent decades.

RECENT FINDINGS

In recent years, optimized dosing of antibiotics is increasingly being recognized as a cornerstone of management for severe infections including S. aureus bacteraemia. This comprehensive review details the pharmacokinetics/pharmacodynamics (PK/PD) targets for commonly used antistaphylococcal antibiotics and the doses predicted to achieve them in clinical practice. Recent advances in dosing of teicoplanin and use of cefazolin in CNS infections and findings from combination therapy studies are discussed. Drug exposure relationships related to toxicity are also detailed.

SUMMARY

This review details the different PK/PD targets for drugs used to treat S. aureus bacteraemia and how to apply them in various scenarios. The drug doses that achieve them, and the risks of toxicity are also provided.

Peri-operative pharmacokinetics of cefazolin prophylaxis during valve replacement surgery

OBJECTIVE

There is little prospective data to guide effective dosing for antibiotic prophylaxis during surgery requiring cardiopulmonary bypass (CPB). We aim to describe the effects of CPB on the population pharmacokinetics (PK) of total and unbound concentrations of cefazolin and to recommend optimised dosing regimens.

METHODS

Patients undergoing CPB for elective cardiac valve replacement were included using convenience sampling. Intravenous cefazolin (2g) was administered pre-incision and re-dosed at 4 hours. Serial blood and urine samples were collected and analysed using validated chromatography. Population PK modelling and Monte-Carlo simulations were performed using Pmetrics® to determine the fractional target attainment (FTA) of achieving unbound concentrations exceeding pre-defined exposures against organisms known to cause surgical site infections for 100% of surgery (100% fT>MIC).

RESULTS

From the 16 included patients, 195 total and 64 unbound concentrations of cefazolin were obtained. A three-compartment linear population PK model best described the data. We observed that cefazolin 2g 4-hourly was insufficient to achieve the FTA of 100% fT>MIC for Staphylococcus aureus and Escherichia coli at serum creatinine concentrations ≤ 50 μmol/L and for Staphylococcus epidermidis at any of our simulated doses and serum creatinine concentrations. A dose of cefazolin 3g 4-hourly demonstrated >93% FTA for S. aureus and E. coli.

CONCLUSIONS

We found that cefazolin 2g 4-hourly was not able to maintain concentrations above the MIC for relevant pathogens in patients with low serum creatinine concentrations undergoing cardiac surgery with CPB. The simulations showed that optimised dosing is more likely with an increased dose and/or dosing frequency.

A novel method for quantification of cefazolin local tissue concentration in blood, fat, synovium, and bone marrow using liquid chromatography - mass spectrometry

To be effective, the concentration of antibiotic used must exceed the minimum inhibitory concentration (MIC) against infecting organisms at and in the surgical site. Few studies follow antibiotic levels for tissues that are manipulated during surgery. The aim of this work was to develop and validate a novel LC-MS method as well as an efficient extraction technique for the quantification of cefazolin in local tissues and whole blood. This method uses the same efficient extraction method across multiple tissue types affected by orthopedic surgery: blood, fat, synovium, and bone marrow. The ability to quantify cefazolin in these tissues will help identify surgical techniques and antibiotic dosing protocols that better protect patients from infection. The internal standard, 13C2,15N-cefazolin, co-elutes with cefazolin, and was used in calibration curves and tissue extracts as well as for cefazolin recovery and matrix effects. The protocol was rigorously tested, including measurements of reproducibility and calibration curve quality. The recovery of the extraction method ranges from 94% to 113% across all sample types. There is little to no matrix effect on cefazolin signal (98-120%). The developed method was used to determine cefazolin concentrations in tissues of 10 patients undergoing a total knee replacement. Cefazolin blood concentrations were approximately 500 times higher than in adipose, synovium, and bone marrow tissues. This clinical data shows that although the minimum inhibitory concentration is largely surpassed in blood, the concentration of cefazolin in fat, synovium, and bone marrow could be insufficient during a knee replacement. This method of cefazolin quantification will help surgeons optimize antibiotic concentrations in the local tissues during knee replacement surgery and potentially reduce serious post-surgical infections.

Activity fingerprinting of AMR β-lactamase towards a fast and accurate diagnosis

Antibiotic resistance has become a serious threat to global public health and economic development. Rapid and accurate identification of a patient status for antimicrobial resistance (AMR) are urgently needed in clinical diagnosis. Here we describe the development of an assay method for activity fingerprinting of AMR β-lactamases using panels of 7 β-lactam antibiotics in 35 min. New Deli Metallo β-lactamase-1 (NDM-1) and penicillinase were demonstrated as two different classes of β-lactamases. The panel consisted of three classes of antibiotics, including: penicillins (penicillin G, piperacillin), cephalosporins (cefepime, ceftriaxone, cefazolin) and carbapenems (meropenem and imipenem). The assay employed a scheme combines the catalytic reaction of AMR β-lactamases on antibiotic substrates with a flow-injected thermometric biosensor that allows the direct detection of the heat generated from the enzymatic catalysis, and eliminates the need for custom substrates and multiple detection schemes. In order to differentiate classes of β-lactamases, characterization of the enzyme activity under different catalytic condition, such as, buffer composition, ion strength and pH were investigated. This assay could provide a tool for fast diagnosis of patient AMR status which makes possible for the future accurate treatment with selected antibiotics.

The use of antibiotic-loaded bone cement and systemic antibiotic prophylactic use in 2,971,357 primary total knee arthroplasties from 2010 to 2020: an international register-based observational study among countries in Africa, Europe, North America, and Oceania

BACKGROUND AND PURPOSE

Antibiotic-loaded bone cement (ALBC) and systemic antibiotic prophylaxis (SAP) have been used to reduce periprosthetic joint infection (PJI) rates. We investigated the use of ALBC and SAP in primary total knee arthroplasty (TKA).

PATIENTS AND METHODS

This observational study is based on 2,971,357 primary TKAs reported in 2010-2020 to national/regional joint arthroplasty registries in Australia, Denmark, Finland, Germany, Italy, the Netherlands, New Zealand, Norway, Romania, South Africa, Sweden, Switzerland, the UK, and the USA. Aggregate-level data on trends and types of bone cement, antibiotic agents, and doses and duration of SAP used was extracted from participating registries.

RESULTS

ALBC was used in 77% of the TKAs with variation ranging from 100% in Norway to 31% in the USA. Palacos R+G was the most common (62%) ALBC type used. The primary antibiotic used in ALBC was gentamicin (94%). Use of ALBC in combination with SAP was common practice (77%). Cefazolin was the most common (32%) SAP agent. The doses and duration of SAP used varied from one single preoperative dosage as standard practice in Bolzano, Italy (98%) to 1-day 4 doses in Norway (83% of the 40,709 TKAs reported to the Norwegian arthroplasty register).

CONCLUSION

The proportion of ALBC usage in primary TKA varies internationally, with gentamicin being the most common antibiotic. ALBC in combination with SAP was common practice, with cefazolin the most common SAP agent. The type of ALBC and type, dose, and duration of SAP varied among participating countries.

Bacterial profile, antimicrobial resistance, and molecular detection of ESBL and quinolone resistance gene of uropathogens causing urinary tract infection in the southeastern part of Bangladesh

Humans frequently contract urinary tract infections (UTIs), which can be brought on by uropathogens (UPs) that are multi-drug resistant. Treatment for UTIs brought on by pathogenic UPs that produce extended-spectrum lactamases (ESBLs) is more costly and potentially fatal. As a result, the objective of this study was to use culture, biochemical, and 16S rRNA sequencing to identify and characterize UPs isolated from outpatients in Noakhali, Bangladesh, who had symptoms of UTIs. ESBL gene identification and quinolone resistance gene typing were then performed on the isolates using polymerase chain reaction (PCR). Throughout the trial's 8-month duration, 152 (76%) of 200 urine samples were positive for the presence of UPs. The overall number of UPs recovered was 210, with 39 individuals having multiple UPs present in their samples. Among all of the isolates, Escherichia coli (45.24%, 95/210; 95% confidence interval (CI): 35.15-57.60%), Enterobacter spp. (24.76%, 52/210; CI: 19.15-35.77%), Klebsiella spp. (20.95%; 44/210; CI: 15.15-30.20%), and Providencia spp. (9.05%; 19/210; CI: 4.95-19.25%) were the four most prevalent bacteria found in the isolates. The UPs displayed a very high level of resistance to piperacillin 96.92% (126/130), ampicillin 90% (117/130), nalidixic acid 77.69% (101/130), cefazolin 70% (91/130), amoxicillin 50% (55/130), cefazolin 42.31% (55/130), nitrofurantoin 43.08% (56/130), and ciprofloxacin 33.08% (43/130), whereas resistance to netilmicin (3.85%), amikacin (4.62%), and imipenem (9.23%) was low. Individually, every species of E. coli and Providencia spp. showed greater ampicillin, amikacin, cefazolin, cefazolin, and nalidixic acid resistance than the others. The bivariate results indicate several antibiotic pairings, and isolates had meaningful associations. All MDR isolates were subjected to PCR, which revealed that blaCTX-M-15 genes predominated among the isolates, followed by the blaTEM class (37%). Isolates also had the qnrS, aac-6´-Ib-cr, and gyrA genes. The findings provide worrying indications of a major expansion of MDR isolates in the study locations, particularly the epidemiological balCTX-M 15, with the potential for the transmission of multi-drug-resistant UP strains in the population.

Impact of the cefazolin shortage on the selection and cost of parenteral antibiotics during the supply disruption period in Japan: A controlled interrupted time series analysis

BACKGROUND

A serious shortage of cefazolin (CEZ) occurred in Japan in 2019. We compared the impact of the CEZ shortage on the selection of parenteral antibiotics at affected and non-affected hospitals.

METHODS

The data were extracted from a nationwide Japanese administrative database and included all hospitalized cases between April 2016 and December 2020. We defined 'hospitals with shortage' as those hospitals with a statistically significant decrease in the use of CEZ during the supply disruption period compared to the same months of the previous year; other hospitals as 'hospitals without shortage'. We determined the proportion of each selected parenteral antibiotic use to the sum of all selected antibiotic use in the two groups of hospitals during the supply disruption period and during the same months of the previous year. A controlled interrupted time series (CITS) analysis was conducted to estimate the impact of the CEZ shortage on each antibiotic use and the cost of all parenteral antibiotics per patient day in hospitals with shortage as compared to those without shortage.

RESULTS

In the hospitals with shortage, the proportion of CEZ use to the sum of all selected antibiotics decreased (23.5-11.1%). The decrease in CEZ use was mainly offset by the use of ceftriaxone, ceftriaxone, and ampicillin/sulbactam. The CITS analysis showed a statistically significant increase in the use of broader-spectrum beta-lactams and clindamycin during the supply disruption period (flomoxef up 58.1%, cefotiam up 63.1%, cefmetazole up 14.5%, ceftriaxone up 13.9%, and clindamycin up 20.1%). The analysis showed no statistically significant change in the cost of all parenteral antibiotics per patient day.

CONCLUSIONS

During the CEZ supply disruption, there was a statistically significant increase in the use of broader-spectrum beta-lactams and clindamycin in hospitals with shortage compared with those without shortage.

Perovskite quantum dots as a chemiluminescence platform for highly sensitive assay of cefazolin

This paper reports on a chemiluminescence (CL) probe consist of CsPbBr₃ quantum dots (QDs) in organic phase together with Fe(II) and K₂S₂O₈ in aqueous medium for the highly selective and sensitive determination of the antibiotic, cefazolin (CFZ). The CsPbBr₃perovskite QDs prepared by the ligand assisted reprecipitation method, exhibit a narrow fluorescence at 533 nm under 460 nm excitation with a high quantum yield (42 %). The Fe(II) - S₂O₈^2- as an ultra-weak CL system is converted to a rather strong CL sensing platform in the presence of organic-phase CsPbBr₃ QDs. It was observed that CFZ exerts an enhancement effect on the CL signal of the designed probe in the linear range of 25 - 300 nM, with a low limit of detection (9.6 nM). The introduced sensor has broad application prospects in biosensing, food detection, and other fields with recovery ranging from 94 to 106 %.

Corynebacterium Keratitis: Pure Versus Mixed Infection and Antibiotic Susceptibility Patterns From Different Tertiary Eye Care Centers

PURPOSE

The objective of this study was to compare the clinical and microbiological profiles of culture-proven pure Corynebacterium keratitis with mixed infection and their antibiotic susceptibility patterns over a 2-year period.

METHODS

A retrospective analysis of culture-proven cases of Corynebacterium keratitis over a 2-year period was performed in 3 different tertiary eye care centers. All isolates were tested for antibiotic susceptibility in vitro using the disc-diffusion method for 7 antibiotics.

RESULTS

Altogether 108 cases were identified as culture-positive Corynebacterium keratitis in 3 tertiary eye care centers. Of these, 60.2% (n = 65) and 39.8% (n = 43) of cases were due to pure Corynebacterium and mixed infection, respectively. The mean duration of symptoms was 23.2 ± 29.6 days. In the mixed-infection group, fungus was identified as the coexistent pathogen in 22 cases (51.1%). Ocular surface disorder was the most common risk factor (33.9%) in Corynebacterium keratitis. The most frequently isolated species was Corynebacterium amycolatum (22.2%) in both groups. Therapeutic keratoplasty was performed in 8.3% of cases. There was no significant difference in the outcome between the 2 groups. Cefazolin resistance was seen in 13.9% of patients, and all isolates were susceptible to vancomycin. The resistance pattern showed emerging resistance toward fluoroquinolone because the isolates were resistant to gatifloxacin (58.3%), moxifloxacin (47.2%), ciprofloxacin (54.6%), and ofloxacin (45.4%).

CONCLUSIONS

Ocular surface disorder is the most common risk factor in Corynebacterium keratitis. Although fluoroquinolones are commonly used as first-line therapy in microbial keratitis, the in vitro resistance pattern indicates that these are less likely to be effective in infection with Corynebacterium species.

Pathogenicity and transcriptome analysis of a strain of Vibrio owensii in Fenneropenaeus merguiensis

Vibrio is an important conditional pathogen in shrimp aquaculture. This research reported a dominant bacteria strain E1 isolated from a shrimp tank with the method of biofloc culture, which was further identified as Vibrio owensii. To understand the interaction between V. owensii and the host shrimp, we studied the pathogenicity of the V. owensii and the molecular mechanisms of the Fenneropenaeus merguiensis immunity during the Vibrio invasion. Drug susceptibility tests showed that V. owensii was resistant to antibiotics streptomycin oxacillin, tetracycline, minocycline, and aztreonam, but highly sensitive to cefazolin, cefotaxime, and ciprofloxacin, and moderately sensitive to cefotaxime, ampicillin, and piperacillin. Lethal concentration 50 (LC₅₀) test was performed to evaluate the toxicity of V. owensii to F. merguiensis. The LC₅₀ of V. owensii infected F. merguiensis after 24, 48, 72, 96, 120, 144 and 168 h were 1.21 × 10⁷, 1.68 × 10⁶, 6.36 × 10⁵, 2.15 × 10⁵, 7.58 × 10⁴, 5.55 × 10⁴ and 4.33 × 10⁴ CFU/mL. In order to explore the molecular response mechanism of F. merguiensis infected with V. owensii, the hepatopancreas of F. merguiensis were sequenced at 24 hpi and 48 hpi, and a total 40,181 of unigenes were obtained. Through comparative transcriptomic analysis, 86 differentially expressed genes (DEGs) (including 38 up-regulated DEGs, and 48 down-regulated DEGs) and 305 DEGs (including 150 up-regulated DEGs, and 155 down-regulated DEGs) were identified at 24 hpi and 48 hpi, respectively. Annotation and classification analysis of these 391 DEGs showed that most of the DEGs were annotated to metableolic and immune pathways, which indicated that F. merguiensis responded to the invasion through the regulation of material metableolism and immune system genes during V. owensii infection. In the KEGG enrichment analysis, some pathways related to immune response were significantly influenced by V. owensii infection, including phagosome, MAPK signalling pathway and PI3K-Akt signalling pathway. In addition, some pathways related to the warburg effect were also significantly enriched after V. owensii infection, including pyruvate metableolism, glycolysis/gluconeogenesis, and citrate cycle (TAC cycle). Further analysis showed that C-type lectins and ficolin were also play important roles in the immune response of F. merguiensis against V. owensii infection. The current research preliminarily revealed the immune response of F. merguiensis to V. owensii infection at the molecular level, which provided valuable information to further understand the disease control and the interaction between shrimp and Vibrio.

Systematic review of the stability of antimicrobial agents in elastomeric devices for outpatient parenteral antimicrobial therapy services based on NHS Yellow Cover Document standards

BACKGROUND

In order to use aseptically prepared elastomeric infusers, outpatient parenteral antimicrobial therapy (OPAT) services require extended stability data for antimicrobial agents to assign a product shelf-life. In the UK, the relevant standards for stability testing and shelf-life assignment are published in 'A Standard Protocol for Deriving and Assessment of Stability-Part 1 (Aseptic Preparations-Small Molecules), commonly called the Yellow Covered Document (YCD). A previous systematic review published in 2017 failed to identify data on the stability of antimicrobials in elastomeric devices for OPAT services that met YCD requirements in force at the time. The aim of this review was to update that search, following a subsequent change to YCD requirements in 2017 and 2019 and expand that dataset to identify progress made in providing assurance about the stability of antimicrobial agents for OPAT services.

METHODS

Searches were undertaken for papers relating to extended stability of antimicrobials. Citations were included when antimicrobial shelf-life was assessed using a stability-indicating method and considered a period of storage, either refrigerated or at room temperature, followed by in-use testing at a temperature at or above 32°C.

RESULTS

Of 267 initial citations, six met the inclusion criteria and underwent full text review for data extraction. Included antimicrobials were cefazolin, ceftazidime, piperacillin/tazobactam, flucloxacillin and ceftolozane/tazobactam. Of these, only flucloxacillin and piperacillin demonstrated YCD compliant stability over the 24-hour infusion period while cefazolin, ceftazidime and ceftolozane/tazobactam could be infused over 12-hour period.

CONCLUSIONS

Contrary to the position found in 2017 review, high-quality data are now available to support the use of a number of antimicrobial agents in extended infusion in elastomeric devices for OPAT services. There is a need to expand the dataset, as well as developing international consensus on the ideal parameters for stability assessment of such infusions in elastomeric devices.

Therapeutic Effects of Boric Acid in a Septic Arthritis Model Induced by Escherichia coli in Rats

The study aimed to evaluate the therapeutic effect of boric acid (BA) in experimentally induced septic arthritis. A total of 30 rats, 6 rats in each group (5 groups), were used in the study. No treatment was applied to the rats in the control group. Only BA was administered intraperitoneally (IP) to the rats in the bor group. Escherichia coli was administered at a single dose of 25 μL, 1 × 10¹⁰ cfu/rat from the right foot pad of the rats, via intra-articular route, to the mice in the arthritis, arthritis-bor, and arthritis-antb groups. Then, BA at a dose of 50 mg/kg and cefazolin at a dose of 25 mg/kg were administered to the rats in the arthritis-bor and arthritis-antb groups, respectively, for 7 days via the IP route. At the end of the study, all animals were euthanized following the ethical rules. Blood and tissue samples were taken from the rats for biochemical and histopathological analyses. The levels of GSH, MDA, Endoglin, Endocan, and TNF-β markers were measured in the blood samples taken. A significant decrease was observed in MDA and Endoglin levels in the boric acid-administered group compared with the arthritis group, while a significant increase was observed at the GSH level. Histopathologically, it was determined that the reactive surrounding tissue response in the bor group was significantly reduced. As a result, a significant decrease in inflammation was found biochemically and histopathologically in the groups treated with BA.

Plaque rupture and neovascularisation detected with optical coherence tomography in a case of Kounis syndrome

Kounis syndrome is an allergic acute coronary syndrome (ACS) characterised by coronary artery spasm, plaque erosion/rupture or stent thrombosis caused by mast cell and other interacting cell activation. Although intracoronary imaging modalities can detect those ACS mechanisms, Kounis syndrome due to plaque rupture has rarely been reported using intracoronary imaging. We present the case of a woman in her 70s who developed Kounis syndrome as a result of plaque rupture detected with optical coherence tomography (OCT). She had non-ST-segment elevation ACS as a result of anaphylaxis to cefazolin. Coronary angiography revealed severe stenosis in the left anterior descending artery; angiographically undetectable plaque rupture was detected using OCT. OCT also revealed intraplaque neovascularisation, suggesting that the culprit plaque had been vulnerable. OCT can aid in understanding the underlying mechanisms of Kounis syndrome.

Adsorption of cefazolin on organoclay: experimental design, characterization, and a complete batch study

Cefazolin (CFZ) is a ubiquitous antibiotic in hospital settings and has been recognized as an emerging contaminant due to its ecotoxicity. Despite the growing concern around this compound, the literature addressing feasible advanced techniques for CFZ uptake from aqueous matrices is still scarce. Thus, the objective of this work was to evaluate the adsorption of cefazolin on Spectrogel® organoclay in a batch system as an efficient remediation method. The optimization of experimental conditions was determined by a central composite rotational design. A pH study, as well as equilibrium, kinetic, and thermodynamic assays, was performed to assess the adsorption of CFZ on Spectrogel®. The kinetic and equilibrium models that best described the system were the external mass transfer resistance and Sips models, respectively. A removal efficiency above 80% was achieved, and the maximum adsorption capacity at 25 °C was 398.6 mg g^-1. The post-process contaminated organoclay was thermally regenerated. The outcomes of this work indicate that Spectrogel® is an environmentally friendly adsorbent for the removal of cefazolin from wastewater.

Assessing the Variability of Antibiotic Management in Patients With Open Hand Fractures Presenting to the Pediatric Emergency Department

OBJECTIVES

Open hand fractures may be difficult to recognize and treat. There is variability in management and administration of antibiotics for these types of injuries. Unlike open long bone fractures, there is no standardized protocol for antibiotic administration for open hand fractures in children. The objective of this study is to assess the variability of antibiotic management of open hand fractures in children.

METHODS

We performed a retrospective chart review at a tertiary hospital in New York of patients with hand injuries between ages 0 and 18 years presenting to the emergency department during January 2019 and December 2020. Patient encounters were reviewed for open fractures of the hand. Descriptive statistics were included for demographic and physical characteristics.

RESULTS

There were 80 encounters with open hand fractures, of which the most common being tuft fractures (77.5%). The mean age was 7.6 years (SD, 4.7 years) with male predominance (58.8%). Crush injuries were the most common mechanism of injury (78.8%). Bedside repair was performed on 62 encounters (77.5%), of which 45 (72.5%) required nail bed repair, 56 (90.3%) required suturing, and 24 (38.7%) required reduction. Antibiotics were given to 62 (77.5%) encounters, most commonly oral cefalexin (45.2%), oral amoxicillin-clavulanic acid (27.4%), and intravenous cefazolin (14.5%). Median time to antibiotics from emergency department registration to administration was 150 minutes (interquartile range, 92-216 minutes). Antibiotic prescriptions were sent for 71 encounters (88.8%). Seventy seven (96.3%) of the encounters were discharged home.

CONCLUSIONS

Pediatric open hand fractures have a variability of type and timing to antibiotics. Future initiatives should attempt to create standardized guidelines for management of open hand fractures.

A novel quantitative computer-assisted drug-induced liver injury causality assessment tool (DILI-CAT)

Background and aims

We hypothesized that a drug’s clinical signature (or phenotype) of liver injury can be assessed and used to quantitatively develop a computer-assisted DILI causality assessment-tool (DILI-CAT). Therefore, we evaluated drug-specific DILI-phenotypes for amoxicillin-clavulanate (AMX/CLA), cefazolin, cyproterone, and Polygonum multiflorum using data from published case series, to develop DILI-CAT scores for each drug.

Methods

Drug specific phenotypes were made up of the following three clinical features: (1) latency, (2) R-value, and (3) AST/ALT ratio. A point allocation system was developed with points allocated depending on the variance from the norm (or “core”) for the 3 variables in published datasets.

Results

The four drugs had significantly different phenotypes based on latency, R-value, and AST/ALT ratio. The median cyproterone latency was 150 days versus < 43 days for the other three drugs (median: 26 for AMX/CLA, 20 for cefazolin, and 20 for Polygonum multiflorum; p<0.001). The R-value for the four drugs was also significantly different among drugs (cyproterone [median 12.4] and Polygonum multiflorum [median 10.9]) from AMX/CLA [median 1.44] and cefazolin [median 1.57; p<0.001]). DILI-CAT scores effectively separated cyproterone and Polygonum multiflorum from AMX/CLA and cefazolin, respectively (p<0.001). As expected, because of phenotypic overlap, AMX/CLA and cefazolin could not be well differentiated.

Conclusions

DILI-CAT is a data-driven, diagnostic tool built to define drug-specific phenotypes for DILI adjudication. The data provide proof of principle that a drug-specific, data-driven causality assessment tool can be developed for different drugs and raise the possibility that such a process could enhance causality assessment methods.

Molecular characterization and biofilm-formation analysis of Listeria monocytogenes, Salmonella spp., and Escherichia coli isolated from Brazilian swine slaughterhouses

This study aimed to verify the presence of Listeria monocytogenes, Salmonella spp., and Escherichia coli in two Brazilian swine slaughterhouses, as well as to perform antibiograms, detect virulence and antimicrobial resistance genes, and evaluate the in vitro biofilm-forming capability of bacterial isolates from these environments. One Salmonella Typhi isolate and 21 E. coli isolates were detected, while L. monocytogenes was not detected. S. Typhi was isolated from the carcass cooling chamber’s floor, resistant to several antimicrobials, including nalidixic acid, cefazolin, chloramphenicol, doxycycline, streptomycin, gentamicin, tetracycline, and sulfonamide, and contained resistance genes, such as tet(B), tet(C), tet(M), and ampC. It also showed moderate biofilm-forming capacity at 37°C after incubating for 72 h. The prevalence of the 21 E. coli isolates was also the highest on the carcass cooling chamber floor (three of the four samplings [75%]). The E. coli isolates were resistant to 12 of the 13 tested antimicrobials, and none showed sensitivity to chloramphenicol, an antimicrobial prohibited in animal feed since 2003 in Brazil. The resistance genes MCR-1, MCR-3, sul1, ampC, clmA, cat1, tet(A), tet(B), and blaSHV, as well as the virulence genes stx-1, hlyA, eae, tir α, tir β, tir γ, and saa were detected in the E. coli isolates. Moreover, 5 (23.8%) and 15 (71.4%) E. coli isolates presented strong and moderate biofilm-forming capacity, respectively. In general, the biofilm-forming capacity increased after incubating for 72 h at 10°C. The biofilm-forming capacity was the lowest after incubating for 24 h at 37°C. Due to the presence of resistance and virulence genes, multi-antimicrobial resistance, and biofilm-forming capacity, the results of this study suggest a risk to the public health as these pathogens are associated with foodborne diseases, which emphasizes the hazard of resistance gene propagation in the environment.

Genetic Diversity, Antibiotic Resistance, and Pathogenicity of Aeromonas Species from Food Products in Shanghai, China

OBJECTIVE

Aeromonas has recently been recognized as an emerging human pathogen. Aeromonas-associated diarrhea is a phenomenon occurring worldwide. This study was designed to determine the prevalence, genetic diversity, antibiotic resistance, and pathogenicity of Aeromonas strains isolated from food products in Shanghai.

METHODS

Aeromonas isolates ( n = 79) collected from food samples were analyzed using concatenated gyrB- cpn60 sequencing. The antibiotic resistance of these isolates was determined using antimicrobial susceptibility testing. Pathogenicity was assessed using β-hemolytic, extracellular protease, virulence gene detection, C. elegans liquid toxicity (LT), and cytotoxicity assays.

RESULTS

Eight different species were identified among the 79 isolates. The most prevalent Aeromonas species were A. veronii [62 (78.5%)], A. caviae [6 (7.6%)], A. dhakensis [3 (3.8%)], and A. salmonicida [3 (3.8%)]. The Aeromonas isolates were divided into 73 sequence types (STs), of which 65 were novel. The isolates were hemolytic (45.6%) and protease-positive (81.0%). The most prevalent virulence genes were act (73.4%), fla (69.6%), aexT (36.7%), and ascV (30.4%). The results of C. elegans LT and cytotoxicity assays revealed that A. dhakensis and A. hydrophila were more virulent than A. veronii, A. caviae, and A. bivalvium. Antibiotic resistance genes [ tetE, blaTEM, tetA, qnrS, aac(6)-Ib, mcr -1, and mcr-3] were detected in the isolates. The multidrug-resistance rate of the Aeromonas isolates was 11.4%, and 93.7% of the Aeromonas isolates were resistant to cefazolin.

CONCLUSION

The taxonomy, antibiotic resistance, and pathogenicity of different Aeromonas species varied. The Aeromonas isolates A. dhakensis and A. hydrophila were highly pathogenic, indicating that food-derived Aeromonas isolates are potential risks for public health and food safety. The monitoring of food quality and safety will result in better prevention and treatment strategies to control diarrhea illnesses in China.

Detection of Salmonella Typhi in Bile by Quantitative Real-Time PCR

In countries where the incidence of typhoid fever is high, fecal material from short-term carriers of Salmonella Typhi contaminates inadequately treated water supplies. As treated water supplies and improved sanitation become available, chronic (mainly gallbladder) carriers of S. Typhi become important. The objective of this study was to develop a method for detection of S. Typhi in bile by quantitative real-time PCR (qPCR) in patients undergoing cholecystectomy. We evaluated sensitivity and specificity of probesets that target oriC, viaB, fliC-d, STY0201, and stoD. We optimized DNA extraction from bile and compared the sensitivity of culture and our qPCR method to detect S. Typhi in bile samples containing various cephalosporins. With the use of an optimized DNA extraction technique, our limit of detection of S. Typhi in spiked human bile samples was 7.4 × 102 CFU/mL. We observed that S. Typhi could be detected by qPCR in samples containing cefazolin, cefotaxime, or ceftriaxone whereas culture could only detect Typhi in samples containing cefazolin but not cefotaxime or ceftriaxone. Our qPCR detection method for S. Typhi in bile should be preferred in areas where antibiotic usage is common. IMPORTANCE New Salmonella Typhi conjugate vaccines have been deployed, which will potentially lead to a fall in incidence rates of typhoid fever in endemic areas. Identification of chronic carriers of S. Typhi will be important as these individuals can be a potential source of transmission to susceptible persons. To address this public health concern, we have developed a novel method to detect S. Typhi in bile using real-time PCR. Our method can be used to identify carriers of S. Typhi among patients undergoing cholecystectomy (gallbladder removal surgery). The sensitivity of our molecular-based assay was superior to culture when performed in the presence of antibiotics commonly used during surgery. Our methodology will complement efforts to eliminate typhoid disease.

Preparation of a novel clay loaded with Fe (VI) for degradation of cefazolin: performance, pathway, and mechanism

Cephalosporin antibiotics, a group of widely prescribed antibiotics, are frequently detected in wastewater effluent and in the natural aquatic environment. Materials have been sought to effectively degrade the antibiotics. In this study, a novel high-iron clay was prepared with potassium ferrate and montmorillonite via a strong alkaline in situ synthesis method. Degradation of cefazolin sodium (CFZ) by this novel Fe (VI)-clay was investigated. The optimal conditions for the degradation of CFZ were determined using a single factor experiment and response surface optimization method. We found that 89.84% removal efficiency was obtained in 137 min when pH value was 5.16 and Fe (VI)-clay dosage was 0.79 g. The CFZ degradation mechanism was studied by computations on the Frontier Electron Density (FED) in combination with spectroscopic and mass spectroscopic analysis. The spectroscopic characteristics of the products at different stages showed that the oxidation decomposition reaction occurred during the degradation of CFZ by Fe (VI)-clay. Furthermore, FED calculation combined with GC-MS results showed that the degradation pathways of CFZ by the Fe (VI)-clay was mainly the cleavage of β-lactam, thiadiazole, tetrazole, and dihydrothiazine rings.

Adsorption of antibiotic cefazolin in organoclay fixed-bed column: characterization, mathematical modeling, and DFT-based calculations

Cefazolin (CFZ) is an antibiotic widely used in veterinary and human medicine that has been detected in high residual levels in the environment and is therefore considered an emerging contaminant. This work evaluated the adsorption of this contaminant by Spectrogel® type C organoclay, in continuous mode using a fixed-bed column. The fluid dynamics and the effect of the CFZ concentration were evaluated. In addition, prior and post-process organoclay were characterized. The continuous system under the conditions of C₀ = 0.3 mmol/L and Q = 0.1 mL/min presented lower values of mass transfer zone (5.88 cm), whereas the system with C₀ = 0.5 mmol/L and Q = 0.1 mL/min achieved higher CFZ adsorption capacity (20 µmol/g). Phenomenological and mass-transfer models were applied to the experimental data. The dual-site diffusion (DualSD) model better described the breakthrough (BTC) data. Furthermore, density functional theory (DFT) calculation was performed at the molecular level to provide a better comprehension of CFZ adsorption.

Development and characterization of a dry reservoir-hydrogel-forming microneedles composite for minimally invasive delivery of cefazolin

Cefazolin (CFZ) is one of the most extensively used cephalosporins. This antibiotic exerts its bactericidal activity by interfering with bacterial cell wall formation, leading to bacteriolysis. CFZ is highly polar, resulting in the drug having poor oral bioavailability. Accordingly, the antibiotic is administered via intramuscular or intravenous injections, which are both painful and invasive. Due to these limitations, there is an impetus to explore alternative drug delivery platforms which offer a minimally invasive approach to delivery CFZ into and across the skin. The current work presents the development of a composite pharmaceutical system composed of hydrogel-forming microneedles (MNs) in tandem with CFZ dry reservoirs. The hydrogel system was fabricated from Gantrez® S-97 and Carbopol® 974P NF crosslinked with PEG 10,000. Swelling kinetic studies showed that the hydrogel system developed was capable of achieving 4000% swelling in PBS pH 7.4. In addition, results from a solute diffusion study showed that CFZ was able to achieve ≈100% cumulative permeation across the swollen hydrogel film. When formulated into MNs, the hydrogel system was capable of breaching the stratum corneum, resulting in intradermal insertion of the hydrogel forming MNs into ex vivo neonatal porcine skin, as evidenced from optical coherence tomography. In addition, two different CFZ loaded dry reservoirs consisting of directly compressed tablets (DCT) and lyophilised (LYO) wafers were formulated and characterised. These dry reservoir systems showed fast dissolution, dissolving in phosphate buffer saline pH 7.4 in less than one minute. In vitro permeation studies, using full thickness ex vivo neonatal porcine skin were conducted. HPLC analysis demonstrated the dry reservoir combination consisting of DCT with hydrogel-forming MNs was capable of achieving up to 80 µg CFZ delivery into the epidermis within 2 hours of application. In addition, DCT reservoir coupled with hydrogel-forming MNs were able to deliver CFZ up to 1.8 mg into and across the skin at 24 hours. Should this system be translated into clinical practice, it may provide a minimally invasive strategy to administer CFZ for the treatment of infections such as septic arthritis, osteomyelitis and cellulitis.

Impact and quality of antimicrobial use in a referral pediatric intensive care unit

INTRODUCTION

We aimed to describe antimicrobial use (AU) and quality of prescriptions (QP) in a 28-bed medical-surgical PICU of a European referral children's hospital during 2019.

METHODS

AU data were expressed as days-of-therapy (DOT) over 100 days-present (DP) and as length-of-treatment (LOT). QP was based on monthly cross-sectional point-prevalence surveys. Length-of-stay (LOS), readmission rates (RR), and mortality rates (MR) were also collected.

RESULTS

PICU AU accounted for 13.5% of the global hospital AU; the median PICU density of AU was 1.4 (IQR 1.3-1.5) times higher than that of the rest of the hospital areas. Antibacterials represented 88.5% of the overall AU, cefazolin and amoxicillin-clavulanate being the most used drugs. A high QP rate was observed (149/168 optimal, 88.9%), with room for improvement in prophylactic regimens and de-escalation of broad-spectrum regimens. LOT, LOS, RR, and MR remained stable.

CONCLUSIONS

PICU AU represented a major portion of the global hospital AU. Despite high QP rates, prophylactic and broad-spectrum antibiotic regimens were optimizable.

Aerosol inhalation delivery of cefazolin in mice: Pharmacokinetic measurements and antibacterial effect

Aerosol inhalation delivery of cefazolin, a broad-spectrum first-generation cephalosporin antibiotic, was investigated. Inhalation system based on ultrasonic nebulizer was developed for the generation of dry cefazolin aerosol within mean particle diameter range 0.5-3.0 μm and mass concentration 0.01-3 μg/cm³. Pharmacokinetic measurements were carried out for the aerosolized form of cefazolin delivered in mice using nose-only chamber. Cefazolin concentrations in blood serum and in the lungs of mice were measured as a function of time by means of high performance liquid chromatography. Body-delivered dose depending on particle size, concentration and inhalation time as well as other pharmacokinetic parameters were determined. The antibacterial effect of aerosolized cefazolin was assessed through the aerosol inhalation treatment of mice infected with Klebsiella pneumoniae. Survival rate for infected mice after the treatment with cefazolin aerosol demonstrated high antibacterial efficiency of the inhalation delivery of cefazolin in comparison with intraperitoneal delivery.

Infection after Open Long Bone Fractures: Can we Improve on Prophylaxis?

INTRODUCTION

Current standards recommend antibiotic prophylaxis administered after open fracture injury. The purpose of this study was to assess culture results in patients with open fracture-associated infections, hypothesizing that cultures obtained do not vary by Gustilo-Anderson (GA) classification.

METHODS

We examined cultured bacterial species from patients with open long bone fractures that underwent irrigation and debridement at a Level 1 trauma center (2008-2016), evaluating our current and two hypothetical antibiotic protocols to assess whether they provided appropriate coverage. The antibiotic protocols included protocols 1 (cefazolin, with gentamicin added for type III fractures), 2 (vancomycin and cefepime) and 3 (ceftriaxone).

RESULTS

GA classification was not associated with bacterial gram stain (P = 0.161), nor was it predictive of mono- versus polymicrobial infection (P = 0.094). Of 42 culture-positive infections, 31 were type III and 11 were type I or II fractures. 27% of the infections for type I or II fractures were caused by organisms targeted by protocol 1 (OR 0.18, 95% CI 0.04-0.82; P = 0.027). There was no difference in coverage by fracture type among protocol 2 (P = 0.771) or protocol 3 (P = 0.891). For type III fractures, protocol 2 provided 94% appropriate coverage compared to 68% and 61% coverage by protocols 1 and 3, respectively.

CONCLUSION

For open fractures complicated by infection, isolated bacterial organisms do not correlate with GA open fracture classification, suggesting that hypothetical protocol 2 should be used for all fracture types. Protocol 2's broad coverage, across all GA fracture types, may prevent infection by organisms not covered by current antibiotic prophylaxis.

l-Cysteine directing synthesis of BiOBr nanosheets for efficient cefazolin photodegradation: The pivotal role of thiol

Cefazolin (CFZ) is widely present in the wastewater treatment effluents and in receiving waters and has caused severe impacts to the ecosystem. CFZ degradation by photocatalysis has attracted increasing attention due to its eco-friendly features. Herein, we presented a green synthesis strategy for a highly active BiOBr photocatalyst for CFZ removal with L-cysteine as a directing agent, and the role of thiol in cysteine for facets control and morphology regulation was discussed. We found that the photoactivity of cysteine-induced BiOBr nanosheet was much higher than those prepared by using arginine and glycine as directing agent. Further experiments showed that the cysteine preferentially coordinated Bi³⁺ with thiol rather than carboxyl. The strong interactions of thiol group with the external surface of the BiOBr crystals stabilize the small crystals that have high surface energy without the cysteine. Such a chemical environment favors forming BiOBr crystalline with small size of high surface area and oriented growth in [110] direction, which facilitates the photogenerated electron-hole separation to achieve significantly promoted photocatalytic activity. Moreover, the cysteine-directed BiOBr nanosheets displayed good photoreactivity to more pollutants (i.e. rhodamine B, cefradine and cefoperazone sodium) and excellent reusability as verified via seven consecutive recycle experiments. The proper photocatalyst dosage (0.4 g/L), relatively acidic water environment (pH 3.4) and high temperature (35 °C) would be beneficial to CFZ photodegrdation by BiOBr. Also, the CFZ photodegradation mechanism and degradation pathway were also proposed by combining radical trapping experiments and electron spin resonance (ESR) test with LC-MS analysis in the photocatalytic process.

Clinical study of herbal mixture "Diding Oral Medicine" as an alternative to preventative antibiotics in perioperative hemorrhoids: A CARE-compliant article

To study the clinical effects of Diding Oral Medicine as an alternative to preventative antibiotics in perioperative hemorrhoids.From August 2017 to February 2018, a total of 214 patients who were treated with external exfoliation and internal ligation of mixed hemorrhoids in our hospital were divided into the control group and experimental group by way of stratified random (107 cases in each group). Patients in the control group were given antibiotics preventatively before operation, while patients in the experimental group took Diding Oral Medicine before operation, and the white blood cell count, neutrophil count, wound recovery, pain score, anal bulge score, and pathogen culture of wound secretions were compared between the 2 groups.There was no significant difference in white blood cell count and neutrophil count between both groups before and after operation (P > .05). The wound seepage score, wound edema score, and wound area score in the experimental group were lower than those in the control group, and the wound healing in the experimental group was shorter than that in the control group (all P < .05). The pain score and anal bulge score of the experimental group were decreased significantly compared to the control group (P < .05). In addition, the detection rate of pathogenic bacteria in the experimental group was downregulated significantly compared to the control group (P < .05).The Diding Oral Medicine has prominent bacteriostatic and antibacterial effects on patients with hemorrhoids during perioperative period, and promotes wound healing, reduces pain stress, and anal bulge.

In-situ electro-generation and activation of hydrogen peroxide using a CuFeNLDH-CNTs modified graphite cathode for degradation of cefazolin

The modified multifunctional electrodes for electro-Fenton (EF) process are suggested to be promising cathodes for in situ electro-generation and activation of H₂O₂ to produce hydroxyl radicals (^•OH). However, heterogeneous EF process still faces the challenges of limited catalytic activity and releasing of massive amounts of transition metals to the solution after removal of organic pollutants. The main aim of the present investigation was to prepare a cathode containing carbon nanotubes (CNTs) and CuFe nano-layered double hydroxide (NLDH) for degradation and mineralization of cefazolin antibiotic through electro-Fenton process. Structural and electrochemical analyses demonstrated that CuFeNLDH-CNTs nanocomposite was successfully incorporated on the surface of graphite cathode. Due to the increased formation of ^•OH in the reactor, the incorporation of CNTs into NLDH matrix with a catalyst loading of 0.1 g substantially improved the degradation efficiency of cefazolin (89.9%) in comparison with CNTs-coated (28.7%) and bare graphite cathode (22.8%) within 100 min. In the presence of 15 mM of ethanol, the degradation efficiency of cefazolin was remarkably decreased to 43.7% by the process, indicating the major role of ^•OH in the destruction of target molecules. Acidic conditions favored the degradation efficiency of cefazolin by the modified EF process. Mineralization efficiency of the bio-refractory compound was obtained to be 70.1% in terms of chemical oxygen demand (COD) analysis after 300 min. The gas chromatography-mass spectroscopy (GC-MS) analysis was also implemented to identify the intermediate byproducts generated during the degradation of cefazolin in the CuFeNLDH-CNTs/EF reactor.

Tolerability of Cefazolin and Ceftibuten in Patients with IgE-Mediated Aminopenicillin Allergy

BACKGROUND

Side-chain similarities or identities constitute the predominant factor for cross-reactivity between penicillins and cephalosporins, whereas differences in the side-chain structure seem to account for the absence of such cross-reactivity.

OBJECTIVE

We sought to assess the cross-reactivity between penicillins and 2 cephalosporins (ie, cefazolin and ceftibuten) that have side chains different from those of penicillins, as well as to evaluate the possibility of using these cephalosporins in penicillin-allergic subjects.

METHODS

We conducted a prospective study of 131 consecutive subjects who had suffered 170 immediate reactions (mostly anaphylaxis) to penicillins and had positive skin test results to at least 1 penicillin reagent. All patients underwent skin tests with cefazolin and ceftibuten. Patients with negative results were challenged with them.

RESULTS

One participant had positive skin test results to cefazolin and ceftibuten, as well as to all other reagents tested, including aztreonam and carbapenems. All 129 subjects who underwent challenges with cefazolin and ceftibuten tolerated them. One subject refused cephalosporin challenges.

CONCLUSIONS

Subjects with an IgE-mediated hypersensitivity to penicillins could be treated with cephalosporins such as cefazolin and ceftibuten, which are among the cephalosporins that have side-chain determinants different from those of penicillins. Nevertheless, in patients with such hypersensitivity who need these alternative β-lactams, pretreatment skin tests are advisable because of the possibility of coexisting sensitivities or, much less frequently, of a sensitivity to an antigenic determinant of the common β-lactam ring.

Effective removal of cefazolin from hospital wastewater by the electrocoagulation process

The present study evaluated the treatment of hospital wastewater by the electrocoagulation process using aluminum and iron electrodes. The effects of pH, voltage and reaction time on the removal efficiencies of the antibiotic cefazolin, chemical oxygen demand (COD) and turbidity were investigated. The results showed that by increasing reaction time and input voltage, the removal efficiency of pollutants was increased. The highest removal efficiency of cefazolin, COD, and turbidity occurred at neutral pH, which may have been related to the formation of aluminum hydroxide (Al(OH)₃) flocs through the combination of aluminum released from the surface of the electrode and the hydroxide ions present in the solution. The conductivity of the treated wastewater at neutral to alkaline pH decreased compared to acidic pH, which may have been due to the adsorption of anions and cations from the solution by the Al(OH)₃ flocs. The electrode and energy consumption in the present study was higher than in other studies, which may have been due to the high concentration of COD in and the turbidity of the solution.

Nasal Swab Screening for Staphylococcus aureus in Spinal Deformity Patients Treated With Growing Rods

BACKGROUND

Surgical-site infections are one of the most concerning complications in patients treated with growing rods (GR). The purpose of this study was to evaluate the use of preoperative screening for Staphylococcus aureus (SA) for all growing spine procedures, and if this would permit alteration of prophylactic antibiotics to cover the identified resistances.

METHODS

All patients were identified who had SA screening during the course of GR treatment. In otal, 34 patients [23 neuromuscular (NMS), 4 congenital, 4 idiopathic scoliosis (IS), and 3 syndromic] were identified who had 111 preoperative screenings [79 lengthenings, 23 insertions, 6 revisions, and 3 conversions to posterior spinal fusions (PSF)]. Mean age at GR insertion was 5.5 years (2 to 11 y).

RESULTS

There were 11 methicillin-resistant Staphylococcus aureus (MRSA) "+" screenings in 6 patients (5 NMS, 1 IS): 3 in 3 patients before GR insertion and 8 in 3 patients (all 3 were negative at GR insertion screening) at subsequent surgeries. There were 23 methicillin-sensitive Staphylococcus aureus (MSSA) "+" screenings in 12 patients (7 NMS, 2 congenital, 2 IS, 1 syndromic): 2 in 2 patients before GR insertion and 21 in 10 patients at subsequent surgeries (18 lengthenings, 3 revisions). Overall, 13 patients (3 MRSA+10 MSSA) were initially negative but screened positive for the first time at a subsequent surgery (12 lengthenings, 1 GR to PSF). All patients (n=5) with positive screenings before GR insertion were in patients with NMS (3 MRSA, 2 MSSA). On the basis of sensitivities, 9 patients demonstrated SA resistance to cefazolin (8 MRSA and 1 MSSA) and 6 to clindamycin (5 MRSA and 1 MSSA). Hence, if cefazolin was routinely used for all patients 26.5% of patients (9/34) would have been inadequately covered at some point during their GR treatment; clindamycin, 17.7% (6/34).

CONCLUSION

The use of SA nasal swab screening in GR patients identified 9 patients (26.5%) whose prophylactic antibiotics (cefazolin) could be altered to permit appropriate SA coverage.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

[Influence of frequent instillations of anti-infective solutions on eye tissues (an experimental study)]

PURPOSE

To investigate the toxic effects of frequent instillations of anti-infective solutions (antibiotic eye drops - 0.3 and 1.4% tobramycin, 0.5% levofloxacin and 0.5% moxifloxacin; antiseptic eye drops - 0.05% pyloxidine and 0.025% chlorhexidine; antifungal drug - 2 mg/ml fluconazole solution) on ocular tissues.

MATERIAL AND METHODS

The study was conducted on 21 Wistar rats (42 eyes) using method of semi-fine sections.

RESULTS

The majority of antibiotics and antifungal agents do not cause toxic reactions in rats` eyes when instilled with frequent regimen with the exception of 'fortified' 1.4% tobramycin and pyloxidine solutions, which caused a decrease in corneal endothelial cells density and formation of fibrovascular tissue in the anterior chamber.

CONCLUSION

Frequent instillations of antimicrobial drug solutions is a safe method for the treatment of purulent corneal ulcers and purulent keratitis. The exceptions were solutions of 'fortified' 1.4% tobramycin and piloxidine (vitabact).

High tolerance of and removal of cefazolin sodium in single-chamber microbial fuel cells operation

Single-chamber microbial fuel cells (MFCs) have been shown to be a promising approach for cefazolin sodium (CFZS)-contaminated wastewater treatment, in terms of electricity production, high CFZS tolerance and effective CFZS removal. MFCs exposed to CFZS loadings up to 100 mg L^-1, produced stable power of 18.2 ± 1.1 W m^-3 and a maximum power of 30.4 ± 2.1 W m^-3, similar to that of CFZS-free MFCs (stable power 19.4 ± 0.8 W m^-3 and maximum power 32.5 ± 1.6 W m^-3), notwithstanding a longer acclimitisation MFC activation. More anodophilic genera (i.e. Acinetobacter, Stenotrophomonas, Lysinibacillus) and antibiotic-resisting genera (i.e. Dysgonomonas) were enriched in CFZS acclimitised anodes. Both the thickness of biofilms and the duration of CFZS acclimitisation were essential for the development of high CFZS tolerance (e.g. 450 mg L^-1). The inhibition of MFCs by CFZS was reversible. The present MFCs generated a CFZS removal rate of 1.2-6.8 mg L^-1 h^-1 without any apparent inhibition of electricity production.