Cefazolin as a predictor of urinary cephalosporin activity in indicated Enterobacterales.

Traditionally, cephalothin susceptibility results were used to predict the susceptibility of additional cephalosporins; however, in 2013-2014, the Clinical and Laboratory Standards Institute (CLSI) revisited this practice and determined that cefazolin is a more accurate proxy than cephalothin for uncomplicated urinary tract infections (uUTIs). Therefore, a cefazolin surrogacy breakpoint was established to predict the susceptibility of seven oral cephalosporins for Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis in the context of uUTIs. Clinical microbiology laboratories face several operational challenges when implementing the cefazolin surrogacy breakpoint, which may lead to confusion for the best path forward. Here, we review the historical context and data behind the surrogacy breakpoints, review PK/PD profiles for oral cephalosporins, discuss challenges in deploying the breakpoint, and highlight the limited clinical outcome data in this space.

Dose regimen optimization of cephalothin for surgical prophylaxis against Staphylococcus aureus and coagulase negative staphylococci in dogs by pharmacokinetic/pharmacodynamic modeling.

First generation cephalosporins such cephalothin of cefazolin are indicated for antimicrobial prophylaxis for clean and clean contaminated surgical procedures because its antimicrobial spectrum, relative low toxicity and cost. Anesthesia and surgery could alter the pharmacokinetic behavior of different drugs administered perioperative by many mechanisms that affect distribution, metabolism or excretion processes. Intravenous administration of the antimicrobial within 30 and 60 min before incision is recommended in order to reach therapeutic serum and tissue concentrations and redosing is recommended if the duration of the procedure exceeds two half-life of the antimicrobial. To the author's knowledge there are no pharmacokinetic studies of cephalothin in dogs under anesthesia/surgery conditions. The aim of this study was (1) to evaluate the pharmacokinetics of cephalothin in anesthetized dogs undergoing ovariohysterectomy by a nonlinear mixed-effects model and to determine the effect of anesthesia/surgery and other individual covariates on its pharmacokinetic behavior; (2) to determine the MIC and conduct a pharmacodynamic modeling of time kill curves assay of cephalothin against isolates of Staphylococcus spp. isolated from the skin of dogs; (3) to conduct a PK/PD analysis by integration of the obtained nonlinear mixed-effects models in order to evaluate the antimicrobial effect of changing concentrations on simulated bacterial count; and (4) to determine the PK/PD endpoints and PK/PDco values in order to predict the optimal dose regimen of cephalothin for antimicrobial prophylaxis in dogs. Anesthesia/surgery significantly reduced cephalothin clearance by 18.78%. Based on the results of this study, a cephalothin dose regimen of 25 mg/kg q6h by intravenous administration showed to be effective against Staphylococcus spp. isolates with MIC values ≤2 µg/mL and could be recommended for antimicrobial prophylaxis for clean surgery in healthy dogs.

Unlocking the mechanism of action: a cost-effective flow cytometry approach for accelerating antimicrobial drug development.

Antimicrobial resistance is one of the greatest challenges to global health. While the development of new antimicrobials can combat resistance, low profitability reduces the number of new compounds brought to market. Elucidating the mechanism of action is crucial for developing new antimicrobials. This can become expensive as there are no universally applicable pipelines. Phenotypic heterogeneity of microbial populations resulting from antimicrobial treatment can be captured through flow cytometric fingerprinting. Since antimicrobials are classified into limited groups, the mechanism of action of known compounds can be used for predictive modeling. We demonstrate a cost-effective flow cytometry approach for determining the mechanism of action of new compounds. Cultures of Actinomyces viscosus and Fusobacterium nucleatum were treated with different antimicrobials and measured by flow cytometry. A Gaussian mixture mask was applied over the data to construct phenotypic fingerprints. Fingerprints were used to assess statistical differences between mechanism of action groups and to train random forest classifiers. Classifiers were then used to predict the mechanism of action of cephalothin. Statistical differences were found among the different mechanisms of action groups. Pairwise comparison showed statistical differences for 35 out of 45 pairs for A. viscosus and for 32 out of 45 pairs for F. nucleatum after 3.5 h of treatment. The best-performing random forest classifier yielded a Matthews correlation coefficient of 0.92 and the mechanism of action of cephalothin could be successfully predicted. These findings suggest that flow cytometry can be a cheap and fast alternative for determining the mechanism of action of new antimicrobials.IMPORTANCEIn the context of the emerging threat of antimicrobial resistance, the development of novel antimicrobials is a commonly employed strategy to combat resistance. Elucidating the mechanism of action of novel compounds is crucial in this development but can become expensive, as no universally applicable pipelines currently exist. We present a novel flow cytometry-based approach capable of determining the mechanism of action swiftly and cost-effectively. The workflow aims to accelerate drug discovery and could help facilitate a more targeted approach for antimicrobial treatment of patients.

Assessment and treatment of compulsive exercise in anorexia nervosa - A combined investigation of Compulsive Exercise Activity Therapy (LEAP) and Compulsive Exercise Test subscales.

INTRODUCTION: Compulsive exercise is a transdiagnostic feature of eating disorders which adversely affects aspects of recovery, such as length of hospitalisation, risk of a chronic outcome, and risk of relapse. CompuLsive Exercise Activity TheraPy (LEAP) aims to reduce compulsive exercise through a cognitive behavioural approach. This study aims to investigate the effect of LEAP on compulsive exercise behaviour using subscales of the Compulsive Exercise Test (CET), a measure of exercise in individuals with eating disorders. Predictive validity of the CET's subscales and its ability to predict eating psychopathology are investigated. METHOD: This study used data from a randomized controlled trial of LEAP (1). Linear mixed modelling was used to investigate the effect of LEAP on compulsive exercise behaviour, and the predictive ability of CET subscales on various outcomes. The CET was compared to other exercise measures to assess its superiority in predicting eating psychopathology. RESULTS: LEAP was superior in reducing the scores of the CET's Avoidance and Rule Driven Behaviour and Exercise Rigidity subscales. All subscales made a contribution to the respective models. The CET was superior to other measures in predicting eating pathology. CONCLUSION: The results lend credibility to LEAP's ability to reduce core parts of compulsive exercise. The CET has been found to target important aspects of compulsive exercise behaviour, and has was superior to other exercise measures in predicting eating psychopathology.

No difference in risk of revision due to infection between clindamycin and cephalosporins as antibiotic prophylaxis in cemented primary total knee replacements: a report from the Norwegian Arthroplasty Register 2005-2020.

BACKGROUND AND PURPOSE: Systemic antibiotic prophylaxis with clindamycin, which is often used in penicillin- or cephalosporin-allergic patients', has been associated with a higher risk of surgical revision for deep prosthetic joint infection (PJI) than cloxacillin in primary total knee replacement (TKR). We aimed to investigate whether clindamycin increases the risk of surgical revisions due to PJI compared with cephalosporins in primary cemented TKR. PATIENTS AND METHODS: Data from 59,081 TKRs in the Norwegian Arthroplasty Register (NAR) 2005-2020 was included. 2,655 (5%) received clindamycin and 56,426 (95%) received cephalosporins. Cox regression analyses were performed with adjustment for sex, age groups, diagnosis, and ASA score. Survival times were calculated using Kaplan-Meier estimates and compared using Cox regression with revision for PJI as endpoint. The cephalosporins cefalotin and cefazolin were also compared. RESULTS: Of the TKRs included, 1.3% (n = 743) were revised for PJI. 96% (n = 713) had received cephalosporins and 4% (n = 30) clindamycin for perioperative prophylaxis. Comparing cephalosporins (reference) and clindamycin, at 3-month follow-up the adjusted hazard ratio rate (HRR) for PJI was 0.7 (95% confidence interval [CI] 0.4-1.4), at 1 year 0.9 (CI 0.6-1.5), and at 5 years 0.9 (CI 0.6-1.4). Analysis using propensity score matching showed similar results. Furthermore, comparing cefalotin (reference) and cefazolin, HRR was 1.0 (CI 0.8-1.4) at 3 months and 1.0 (CI 0.7-1.3) at 1-year follow-up. CONCLUSION: We found no difference in risk of revision for PJI when using clindamycin compared with cephalosporins in primary cemented TKRs. It appears safe to continue the use of clindamycin in penicillin- or cephalosporin-allergic patients.

Disc Test for Detecting Staphylococcus aureus Strains Producing Type A and Type C ß-Lactamases.

Staphylococcus aureus can produce ß-lactamases capable of hydrolyzing penicillins and first-generation cephalosporins. The propensity of type A and type C ß-lactamase-producing S. aureus (TAPSA and TCPSA) to hydrolyze cefazolin at a high inoculum is termed the cefazolin inoculum effect (CIE). Strains with a CIE have a theoretical risk of causing treatment failure and are unable to be detected routinely by most laboratories. We developed a high-performing yet straightforward ß-lactamase disc test that identifies and differentiates both TAPSA and TCPSA and is suitable for routine diagnostic laboratory workflows. Clinical isolates of S. aureus resistant to penicillin were identified, and their blaZ genes were sequenced. MICs were determined at low and high inocula (5 × 105 CFU/mL and 5 × 107 CFU/mL), and isolates demonstrating a CIE were characterized. A semimechanistic model was established to describe differential hydrolysis patterns, and candidate models were iteratively assessed using area-under-the-curve analysis from competitor receiver operating characteristic (ROC) curves. Biomarker thresholds were derived from Youdon index-derived optimal cutoff values. Genetic analysis of 99 isolates identified 26 TAPSA isolates and 45 TCPSA isolates. The model best differentiating TAPSA from non-TAPSA utilized cefazolin-to-cephalothin ratio analysis (sensitivity, 96.2%; specificity, 98.6%). The model best differentiating TCPSA from non-TCPSA incorporated cefazolin, cephalothin, and oxacillin (sensitivity, 88.6%; specificity, 96.6%). TAPSA and TCPSA can be differentiated using three antibiotic discs on a single agar plate. The test has potential value in typing the ß-lactamase type from isolates from patients that are candidates for or have failed cefazolin therapy. IMPORTANCE The key significance of this article is that it details a straightforward method of performing a disc test that can differentiate Staphylococcus aureus isolates that are likely to be associated with a cefazolin inoculum effect and theoretical risk of cefazolin treatment failure from isolates that are less likely to be associated with a cefazolin inoculum effect.

Analysis of the Antimicrobial and Anti-Biofilm Activity of Natural Compounds and Their Analogues against Staphylococcus aureus Isolates.

(1) Background: Staphylococcus aureus (S. aureus) is one of the most frequent causes of biofilm-associated infections. With the emergence of antibiotic-resistant, especially methicillin-resistant S. aureus (MRSA), there is an urgent need to discover novel inhibitory compounds against this clinically important pathogen. In this study, we evaluated the antimicrobial and anti-biofilm activity of 11 compounds, including phenyl propenes and phenolic aldehydes, eugenol, ferulic acid, sinapic acid, salicylaldehyde, vanillin, cinnamoyl acid, and aldehydes, against drug-resistant S. aureus isolates. (2) Methods: Thirty-two clinical S. aureus isolates were obtained from Alkhidmat Diagnostic Center and Blood Bank, Karachi, Pakistan, and screened for biofilm-forming potential, and susceptibility/resistance against ciprofloxacin, chloramphenicol, ampicillin, amikacin, cephalothin, clindamycin, streptomycin, and gentamicin using the Kirby-Bauer disk diffusion method. Subsequently, 5 representative clinical isolates were selected and used to test the antimicrobial and anti-biofilm potential of 11 compounds using both qualitative and quantitative assays, followed by qPCR analysis to examine the differences in the expression levels of biofilm-forming genes (ica-A, fnb-B, clf-A and cna) in treated (with natural compounds and their derivatives) and untreated isolates. (3) Results: All isolates were found to be multi-drug resistant and dominant biofilm formers. The individual Minimum Inhibitory Concentration (MIC) of natural compounds and their analogues ranged from 0.75−160 mg/mL. Furthermore, the compounds, Salicylaldehyde (SALI), Vanillin (VAN), α-methyl-trans-cinnamaldehyde (A-MT), and trans-4-nitrocinnamic acid (T4N) exhibited significant (15−92%) biofilm inhibition/reduction percentage capacity at the concentration of 1−10 mg/mL. Gene expression analysis showed that salicylaldehyde, α-methyl-trans-cinnamaldehyde, and α-bromo-trans-cinnamaldehyde resulted in a significant (p < 0.05) downregulation of the expression of ica-A, clf-A, and fnb-A genes compared to the untreated resistant isolate. (4) Conclusions: The natural compounds and their analogues used in this study exhibited significant antimicrobial and anti-biofilm activity against S. aureus. Biofilms persist as the main concern in clinical settings. These compounds may serve as potential candidate drug molecules against biofilm forming S. aureus.

Isolation, identification and antibiotic resistance profile of thermophilic Campylobacter species from Bovine, Knives and personnel at Jimma Town Abattoir, Ethiopia.

Thermophilic Campylobacter species are common cause of animal and human bacterial diseases with growing resistance to antimicrobials. The aim of this study was to determine the prevalence and antimicrobial susceptibility pattern of Campylobacter species from bovine, knives and personnel in Jimma Town, Ethiopia. Faecal samples and carcasses swabs were collected from cattle systematically selected from the annual plan of Jimma Municipal Abattoir. Personnel hand and knife swabs were collected after slaughtering each selected cattle. A cross-sectional study with systematic sampling method was conducted from October 2019 to September 2020 for the isolation, identification and antimicrobial susceptibility pattern of thermophilic Campylobacter species. Isolation and identification of Campylobacter species were performed according to the techniques recommended by the International Organization for Standardization, and in vitro antibiotic susceptibility testing was screened using the standard agar disc diffusion method as recommended by Clinical and Laboratory Standards Institutions. A total of 684 samples (171 samples from faeces, carcasses, knives and personnel hands, were collected independently). The overall prevalence of thermophilic Campylobacterspecies was 5.6% (38/684). Majority of the isolates were from faecal samples (12.9%, n = 22) followed by carcass swabs(4.1% n = 7), knife swabs(3.5% n = 6) and personnel hand swabs(1.8% n = 3). Isolated and identified species of C.jejuni, C. coli and C. lari accounted for 63.2%, 23.7% and 13.2%, respectively. The isolated Campylobacter species were found to be resistant to Cephalothin (100%), Ampicillin (60.5%), Cefotaxime (60.5%), Chloramphenicol (47.4%) and Tetracycline (42.1%). On the other hand, the isolates were susceptible to Nalidixic acid (86.8%), Ciprofloxacin (86.8%), Sulphamethazole (84.2%), Ceftriaxone (78.9%), Clindamycin (68.4%) and Cefixime (65.8%). 84.2% of the isolates showed multi-drug resistance for three-to-six drug classes. All the C. lari isolates were multidrug resistant. All the three isolated species of Campylobacter were resistant to Cephalothin, and most were multidrug resistant. Isolation of Campylobacter species from faecal, carcass, knife and hand swabs revealed possible risk of contamination and exposure to Campylobacter infection of those who consume raw meat. Therefore, enactment of hygienic practices during the slaughtering process, proper handling and cooking of meat and awareness creation on jurisdictional antibiotic usage are required to avoid Campylobacter infection.

Screening of Antibacterial Efficacy of Chitosan Encapsulated Probiotics (Lactococcus lactis and Lactobacillus curvattus) against Clinical Bacterial Pathogens.

Probiotics frontier in depressing the clinical bacterial pathogens to avoid multidrug resistance phenomenon. The present study aimed to determine the antibacterial efficiency of chitosan encapsulated probiotics isolated from buffalo milk samples against clinical bacterial pathogens. The Agar well method was used for antibacterial activity. Lactococcus lactis (A) and Lactobacillus curvattus (B) were isolated from fresh buffalo milk samples, identified via culturing media, Gram's staining, biochemical tests, and antibiogram analysis. Encapsulation of probiotics was carried out using chitosan and was characterized via a scanning electron microscope. Antibiogram analysis elicit that L. lactis culture (A1) was highly sensitive to chloramphenicol (17.66±0.47 mm), tobramycin (15.33±0.47 mm), and ciprofloxacin (12.33±0.47 mm) and resistant against tetracycline, Penicillin G, Erythromycin, Amoxycillin, Ceftriaxone, Cephalothin, and Cephradine, while L. curvattus culture (B1) was affected by Ceftriaxone (18.67±0.47 mm), Amoxycillin (14.33±0.94 mm), Cephalothin (13.67±0.47 mm), Erythromycin (13.33±0.47 mm), Penicillin G (12.67±0.47 mm), Cephradine (10.33±0.47 mm), and Chloramphenicol (9.67±0.47 mm) and resistant against tetracycline, Tobramycin, and Ciprofloxacin. Antibacterial efficacy of non-encapsulated probiotic cultures was significant and maximum inhibition of bacterial were recorded compared to their cellular components. SEM of encapsulated probiotics revealed that they were successfully covered with a chitosan protective layer and could be effective as bio-preservatives due to being slowly released at the target site. The current study concluded that L. lactis, L. curvattus, and their cellular components have a significant bactericidal effect against infectious pathogens and could be used as a potential therapeutic drug against infectious diseases.

Cefadroxil Comparable to Cephalexin: Minimum Inhibitory Concentrations among Methicillin-Susceptible Staphylococcus aureus Isolates from Pediatric Musculoskeletal Infections.

Cephalexin and cefadroxil are oral first-generation cephalosporins used to treat methicillin-susceptible Staphylococcus aureus (MSSA) infections. Despite its shorter half-life, cephalexin is more frequently prescribed, although cefadroxil is an appealing alternative, given its slower clearance and possibility for less frequent dosing. We report comparative MIC distributions for cefadroxil and cephalexin, as well as for oxacillin, cephalothin, ceftaroline, and cefazolin, for 48 unique clinical MSSA isolates from pediatric patients with musculoskeletal infections. Both cefadroxil and cephalexin had MIC50 values of 2 µg/mL and MIC90 values of 4 µg/mL. MIC50s for oxacillin, cephalothin, and ceftaroline were ≤0.25 µg/mL, and cefazolin's MIC50 was 0.5 µg/mL. While cefadroxil and cephalexin MICs are higher than those for other active agents, the distributions of MICs for cefadroxil and cephalexin are statistically equivalent, suggesting similar in vitro MSSA activities. Cefadroxil should be further considered an alternative agent to cephalexin, although additional work is needed to identify the optimal dose and frequency of these antibiotics for the treatment of serious MSSA infections. IMPORTANCE Cephalexin and cefadroxil are oral antibiotics that are used to treat serious infections due to the bacteria MSSA. While cephalexin is used more commonly, cefadroxil is excreted from the body more slowly; this generally allows patients to take cefadroxil less frequently than cephalexin. In this study, we compared the abilities of cefadroxil, cephalexin, and several other representative intravenous antibiotics to inhibit the growth of MSSA in the laboratory. Bacterial samples were obtained from children with bone, joint, and/or muscle infections caused by MSSA. We found that cefadroxil and cephalexin inhibited the growth of MSSA at similar concentrations, suggesting similar antibacterial potencies. The selected intravenous antistaphylococcal antibiotics generally inhibited bacterial growth with lower antibiotic concentrations. Based on these results, cefadroxil should be further considered an alternative oral antibiotic to cephalexin, although future research is needed to identify the optimal dose and frequency of these antibiotics for serious infections.

Globally Vibrio cholera antibiotics resistance to RNA and DNA effective antibiotics: A systematic review and meta-analysis.

BACKGROUND: Vibrio cholera (V. cholera) is a facultative pathogen that colonizes the small intestine and produces cholerae toxin as the primary virulence factor that causes cholera and fatal diarrhea in humans. In recent decades, V. cholera has emerged as a notorious multidrug-resistant enteric pathogen. This meta-analysis estimated the pooled proportion of V. cholera antimicrobial resistance against RNA and DNA effective antibiotics. METHOD: A systematic search was performed for relevant literature until 05 June 2021 in PubMed, Scopus, Embase, and Web of Science databases. Freeman-Tukey double arcsine transformation was performed to estimate weighted pooled resistance (WPR). RESULTS: The meta-analysis were included 164 articles. The WPR of V. cholera were as follows 76% [67,84] to furazolidone, 65% [29,94] to nitrofurantoin, 55% [44,66] to nalidixic acid, 10% [2,23] to rifampicin, 4%(0, 12) to novobiocin, 4% [2,6] to norfloxacin, 3% [1,4] to ciprofloxacin, 1%(0, 3) to sparofloxacin, 0%(0, 3) to levofloxacin, 0%(0, 2) to ofloxacin, 0%(0, 0) to gatifloxacin. CONCLUSION: V. cholera is a severe problem in Asia and Africa, especially in South Asian countries. The resistance patterns are various in geographical regions. novobiocin 0% (0, 0), and ofloxacin 0% (0, 1) in Africa, gatifloxacin 0% (0, 0), and levofloxacin 0% (0, 6) in Asia and ciprofloxacin 0% (0, 2) in North America are most effective antibiotis. The resistance rate to furazolidone, nalidixic acid, nitrofurantoin, and cephalothin has increased over the years. Monitoring antibiotic resistance and prescribing an appropriate antibiotic is vital to control resistance.

Priming with biocides: A pathway to antibiotic resistance?

AIMS: To investigate the priming effects of sub-inhibitory concentrations of biocides on antibiotic resistance in bacteria. METHODS AND RESULTS: Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were exposed to sub-inhibitory concentrations of biocides via a gradient plate method. Minimum inhibitory concentration (MIC) and antibiotic susceptibility were determined, and efflux pump inhibitors (thioridazine and chlorpromazine) were used to investigate antibiotic resistance mechanism(s). Escherichia coli displayed a twofold increase in MIC (32-64 mg l-1 ) to H2 O2 which was stable after 15 passages, but lost after 6 weeks, and P. aeruginosa displayed a twofold increase in MIC (64-128 mg l-1 ) to BZK which was also stable for 15 passages. There were no other tolerances observed to biocides in E. coli, P. aeruginosa or S. aureus; however, stable cross-resistance to antibiotics was observed in the absence of a stable increased tolerance to biocides. Sixfold increases in MIC to cephalothin and fourfold to ceftriaxone and ampicillin were observed in hydrogen peroxide primed E. coli. Chlorhexidine primed S. aureus showed a fourfold increase in MIC to oxacillin, and glutaraldehyde-primed P. aeruginosa showed fourfold (sulphatriad) and eightfold (ciprofloxacin) increases in MIC. Thioridazine increased the susceptibility of E. coli to cephalothin and cefoxitin by fourfold and twofold, respectively, and both thioridazine and chlorpromazine increased the susceptibility S. aureus to oxacillin by eightfold and fourfold, respectively. CONCLUSIONS: These findings demonstrate that sub-inhibitory concentrations of biocides can prime bacteria to become resistant to antibiotics even in the absence of stable biocide tolerance and suggests activation of efflux mechanisms may be a contributory factor. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates the effects of low-level exposure of biocides (priming) on antibiotic resistance even in the absence of obvious increased biocidal tolerance.

Cephalosporin susceptibility of Staphylococcus aureus strains isolated from commercial rabbit and goats farms in Spain.

Antimicrobial drug resistance is an important problem that challenges veterinary clinicians to provide effective treatments without further spreading resistance to other animals and people. The most commonly used pharmacodynamic parameter to define potency of antimicrobial drugs is minimum inhibitory concentration (MIC). The aim of this study was to evaluate the antibiotic susceptibility of thirty-six strains of Staphylococcus aureus isolated from dairy goats with mastitis and rabbits with chronic staphylococcosis. Four cephalosporins were tested: cephalexin, cephalotin, cefonicid and ceftiofur. MIC tests were performed according to the microdilution broth method. The calculated values of sensitivity in goats and rabbits were 66.67% and 72.22% for cephalexin, 72.22 % and 94.44% for cefonicid, 77.78% and 94.44% for cephalotin and 77.78% and 100% for ceftiofur, respectively. For all antibiotics, MIC90 of S. aureus from rabbits were lower than MIC90 from goats. These data suggest that more antibiotics are used in goat milk production than in rabbit farming. According to MIC values obtained in this study, ceftiofur and cephalotin may be the best option for treating S. aureus infections in lactating goats. For rabbits, ceftiofur showed lowest MIC values, therefore, it could be an alternative to treatment the infections caused by S. aureus in this species.

Evaluation of Probiotic Effects of Lactobacilli on Mutans Streptococci: An In Vitro Study.

AIM: The aim of the present study is to evaluate the probiotic effect of Lactobacillus acidophilus and Lactobacillus rhamnosus on clinical isolates of Mutans Streptococci (MS) and antibiotic susceptibility of these strains to commonly used antibiotics in dentistry. MATERIALS AND METHODS: Plaque samples from permanent first molars were collected and transferred aseptically onto Mitis-Salivarius agar and incubated at 37°C for 24 hours in the presence of 5-10% CO2. Mutans streptococci colonies were identified biochemically using Hi-Strep identification kit. The inhibitory activity of the clinical strains of MS on Lactobacilli was investigated using agar-overlay interference technique. Positive inhibition was appreciated as a clear zone around the Lactobacilli. Disk diffusion assay was done as described by CLSI M100-S25 for antibiotic susceptibility. The zone of growth inhibition caused by Lactobacilli and antibiotics on MS clinical strains was measured directly using a vernier caliper. Statistical analysis was done using independent t-test. RESULTS: Mutans streptococci exhibited positive inhibition with both the probiotic strains and L. acidophilus showed more zones of inhibition than L. rhamnosus. Antibiotic susceptibility of clinical strains of MS showed sensitivity to penicillin and vancomycin, however, tetracycline and erythromycin showed very few resistant strains. The highest zone of inhibition was shown by cephalothin followed by penicillin, tetracycline, ciprofloxacin, erythromycin, and vancomycin. CONCLUSION: L. rhamnosus and L. acidophilus have strong inhibitory effects on clinical strains of MS. Lactobacillus acidophilus showed a higher zone of inhibition. All the clinical strains of MS were sensitive to penicillin and vancomycin. The highest zone of inhibition was shown by cephalothin. CLINICAL SIGNIFICANCE: Dental caries remains silent epidemic and increasing antibiotic resistance is another major challenge that threatens the world. Newer methods such as whole-bacteria replacement therapy using probiotics for decreasing harmful oral pathogens and reducing the intake of antibiotics must be explored. More researches to promote use of probiotics should be initiated due to its possible preventive and health maintenance benefits providing an end to new cavities and antibiotic resistance.

Cephalothin: Review of Characteristics, Properties, and Status of Analytical Methods.

BACKGROUND: Cephalothin (CET), a first generation cephalosporin, is the most efficient cephalosporin against resistant microorganisms. Many studies found in literature and pharmacopeias propose analytical methods which are most commonly HPLC and microbiological assays. OBJECTIVE: This paper shows a brief review of analytical methods to quantify CET with a green analytical chemistry approach. METHOD: The research data were collected from the literature and official compendia. RESULTS: Most of the analytical methods to determine CET were performed by HPLC and agar diffusion in pharmaceuticals, blood, urine, or water. Other analytical methods were found, such as UV-Vis, iodometry, fluorimetry, IR/Raman, electrochemical, and others in less quantity. One important aspect is that these methods use organic and toxic solvents like methanol and acetonitrile and only about 4% of the methods found use water as solvent. CONCLUSIONS: Research about analytical methods for CET focusing on green analytical chemistry is of great importance and could optimize its analysis in pharmaceutical industries and help to guarantee the quality of the product. More than just the development of new techniques, it is possible to enhance the ones that already exist, applying the green analytical chemistry principles. In this way, it will be possible to reduce the environmental impacts caused by other analytical procedures. HIGHLIGHTS: This work shows a brief review of literature and pharmacopeias of analytical methods to quantify CET. Its quality control can be updated to meet the needs of current analytical chemistry and to fit into sustainable and eco-friendly analysis.

KPC-2 ß-lactamase enables carbapenem antibiotic resistance through fast deacylation of the covalent intermediate.

Serine active-site ß-lactamases hydrolyze ß-lactam antibiotics through the formation of a covalent acyl-enzyme intermediate followed by deacylation via an activated water molecule. Carbapenem antibiotics are poorly hydrolyzed by most ß-lactamases owing to slow hydrolysis of the acyl-enzyme intermediate. However, the emergence of the KPC-2 carbapenemase has resulted in widespread resistance to these drugs, suggesting it operates more efficiently. Here, we investigated the unusual features of KPC-2 that enable this resistance. We show that KPC-2 has a 20,000-fold increased deacylation rate compared with the common TEM-1 ß-lactamase. Furthermore, kinetic analysis of active site alanine mutants indicates that carbapenem hydrolysis is a concerted effort involving multiple residues. Substitution of Asn170 greatly decreases the deacylation rate, but this residue is conserved in both KPC-2 and non-carbapenemase ß-lactamases, suggesting it promotes carbapenem hydrolysis only in the context of KPC-2. X-ray structure determination of the N170A enzyme in complex with hydrolyzed imipenem suggests Asn170 may prevent the inactivation of the deacylating water by the 6α-hydroxyethyl substituent of carbapenems. In addition, the Thr235 residue, which interacts with the C3 carboxylate of carbapenems, also contributes strongly to the deacylation reaction. In contrast, mutation of the Arg220 and Thr237 residues decreases the acylation rate and, paradoxically, improves binding affinity for carbapenems. Thus, the role of these residues may be ground state destabilization of the enzyme-substrate complex or, alternatively, to ensure proper alignment of the substrate with key catalytic residues to facilitate acylation. These findings suggest modifications of the carbapenem scaffold to avoid hydrolysis by KPC-2 ß-lactamase.

Rational dosage regimens for cephalothin and cefazolin using pharmacokinetics and pharmacodynamics analysis in healthy horses.

BACKGROUND: First-generation cephalosporins have good activity against gram-positive bacteria and are extensively used in horses. There are few reports of pharmacokinetics and pharmacodynamics (PK/PD) analysis of cephalosporins in horses. OBJECTIVE: To optimise the dosages of the two first-generation cephalosporins cephalothin (CET) and cefazolin (CEZ) in horses using PK/PD concepts. STUDY DESIGN: Experimental study with single administration. METHODS: Drug plasma concentrations following a single intravenous (i.v.) administration of 22 mg/kg bodyweight (bwt) CET in 12 horses and of 10 mg/kg bwt CEZ in six horses were measured using LC-MS/MS. Data were modelled using a nonlinear mixed effect modelling followed by Monte Carlo simulations. Minimum inhibitory concentrations (MICs) against Streptococcus zooepidemicus and Staphylococcus aureus isolated from horses were determined by the microbroth dilution method. RESULTS: The percentages of CET and CEZ binding to serum proteins were 19.9% ± 8.4% and 15.2% ± 8.5% respectively. For both CET and CEZ, the MIC90 against S. zooepidemicus was 0.12 mg/L and against S. aureus was 0.5 mg/L. For CET, to achieve a probability of target attainment (PTA) of 90% for a PK/PD target of a free serum plasma concentration exceeding the MIC90 for 40% of the dosing interval, an empirical CET dosage regimen of 22 mg/kg bwt q8h and 22 mg/kg bwt q4h i.v. administration were required for S. zooepidemicus and S. aureus respectively. For CEZ, the corresponding dosage regimens were 10 mg/kg bwt q12h and 10 mg/kg bwt q8h. MAIN LIMITATIONS: Small sample size only in healthy horses. CONCLUSIONS: For CET, more frequent administration than that currently recommended (22 mg/kg bwt q6-12h) is required to empirically control S. aureus infection in horses. For CEZ, less frequent administration compared to the dosage regimen currently proposed (10-22 mg/kg bwt q6h) could control S. zooepidemicus and S. aureus infections in horses.

Cronobacter spp. isolated from aquatic products in China: Incidence, antibiotic resistance, molecular characteristic and CRISPR diversity.

Cronobacter species (Cronobacter spp.) are important foodborne pathogens that can infect and cause serious life-threatening diseases in infants and immunocompromised elderly. This study aimed to acquire data on Cronobacter spp. contamination of aquatic products in China from 2011 to 2016. In total, 800 aquatic products were tested, and the overall contamination rate for Cronobacter spp. was 3.9% (31/800). The average contamination level of the positive samples was 2.05 MPN/g. Four species and nine serotypes were identified among 33 isolates, of which the C. sakazakii serogroup O1 (n = 9) was the primary serotype. The majority of Cronobacter spp. strains harbored highest resistance against cephalothin (84.8%), followed by tetracycline (6.1%), trimethoprim/sulfameth-oxazole (3.0%) and chloramphenicol (3.0%). Two isolates were resistant to three antibiotics. In total, 26 sequence types and 33 CRISPR types (including 6 new STs and 26 new CTs) were identified, which indicates the extremely high diversity of Cronobacter spp. in aquatic products. Pathogenic C. sakazakii ST4, ST1, and C. malonaticus ST7 were also observed. Overall, this large-scale study revealed the relatively low prevalence and high genetic diversity of Cronobacter spp. in aquatic products in China, and the findings provide valuable information that can guide the establishment of effective measures for the control and precaution of Cronobacter spp. in aquatic products during production processes.

Structures of FOX-4 Cephamycinase in Complex with Transition-State Analog Inhibitors.

Boronic acid transition-state analog inhibitors (BATSIs) are partners with ß-lactam antibiotics for the treatment of complex bacterial infections. Herein, microbiological, biochemical, and structural findings on four BATSIs with the FOX-4 cephamycinase, a class C ß-lactamase that rapidly hydrolyzes cefoxitin, are revealed. FOX-4 is an extended-spectrum class C cephalosporinase that demonstrates conformational flexibility when complexed with certain ligands. Like other ß-lactamases of this class, studies on FOX-4 reveal important insights into structure-activity relationships. We show that SM23, a BATSI, shows both remarkable flexibility and affinity, binding similarly to other ß-lactamases, yet retaining an IC50 value < 0.1 µM. Our analyses open up new opportunities for the design of novel transition-state analogs of class C enzymes.

Postoperative Antibiotic Prophylaxis in Reduction Mammaplasty: A Randomized Controlled Trial.

BACKGROUND: Reduction mammaplasty is a well-established procedure. Studies have shown benefits of using antibiotics in this procedure. Nevertheless, there is no solid evidence to support postoperative antibiotic prophylaxis. The authors evaluated the influence of postoperative antibiotic delivery on infection rates after reduction mammaplasty. METHODS: The authors conducted a randomized trial of noninferiority, with two parallel groups, with triple blinding. The participants were 124 women with breast hypertrophy, with reduction mammaplasty already scheduled, selected consecutively. All patients underwent reduction mammaplasty, performed by the same surgical team, using the superomedial pedicle technique for ascending the nipple-areola complex. All patients received cephalothin (1 g) intravenously at the anesthetic induction and every 6 hours for 24 hours. At hospital discharge, they were assigned randomly to either the placebo (n = 62) or antibiotic group (n = 62) and were instructed to take identical capsules containing 500 mg of cephalexin or placebo, respectively, every 6 hours, for 7 days. Patients were assessed weekly, for 4 weeks, regarding the occurrence of surgical-site infection, by a surgeon who was unaware of the allocation. The criteria and definitions of the Centers for Disease Control and Prevention were adopted. RESULTS: There was no statistical difference between groups regarding age, body mass index, or resected breast tissue weight. The overall surgical-site infection rate was 0.81 percent. Only one patient, allocated to the antibiotic, presented infection, classified as superficial incisional (p = 1.00). In the placebo group, surgery time was higher (p = 0.003). CONCLUSION: The maintenance of antibiotics in the postoperative period of reduction mammaplasty did not influence the rates of surgical-site infection. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, I.