Evaluation of Oral Amoxicillin/Clavulanate for Urinary Tract Infections Caused by Ceftriaxone Non-Susceptible Enterobacterales.

Urinary tract infections (UTIs) are one of the most common infections and are frequently caused by Gram-negative organisms. The rise of resistant isolates has prompted evaluation of alternative therapies, including amoxicillin-clavulanate which has potent activity against Ambler class A enzymes. This study sought to evaluate clinical outcomes of patients with ceftriaxone non-susceptible UTIs receiving amoxicillin-clavulanate or standard of care (SOC). This was a single-center, retrospective, cohort study of adult patients with urinary tract infections caused by a ceftriaxone non-susceptible pathogen who received amoxicillin-clavulanate or SOC. The primary outcome was clinical failure at 90 days. Secondary outcomes included time to failure, isolation of a resistant organism, and hospital length of stay. Fifty-nine patients met study inclusion: 26 received amoxicillin/clavulanate and 33 received SOC. Amoxicillin-clavulanate recipients did not have higher failure rates compared to SOC recipients. For patients requiring hospital admission, hospital length of stay was numerically shorter with amoxicillin-clavulanate. The frequency of amoxicillin-clavulanate and carbapenem-resistant organisms did not differ significantly between groups. Amoxicillin-clavulanate may be a useful alternative therapy for the treatment of ceftriaxone non-susceptible Enterobacterales UTIs.

Amoxicillin-clavulanate Breakpoints Against Enterobacterales: Rationale for Revision by the Clinical and Laboratory Standards Institute.

Amoxicillin-clavulanate (AMC) is among the most frequently prescribed antibiotics globally. It has broad antibacterial activity against gram-positive, gram-negative, and anaerobic bacteria, and has been utilized to treat infections caused by a broad range of pathogens. AMC breakpoints against Enterobacterales were initially set in the 1980s but since then increases in antibiotic resistance, advances in pharmacokinetic (PK)/pharmacodynamic (PD) analyses, and publication of additional clinical data prompted a reassessment by the Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing. Based on this contemporary reappraisal, the CLSI retained the Enterobacterales breakpoints but revised comments regarding dosing associated with use of the AMC breakpoints in the 2022 supplement of M100. This viewpoint provides insight into the CLSI breakpoint reevaluation process and summarizes the data and rationale used to support these revisions to the AMC Enterobacterales breakpoint.

Comparative evaluation of antimicrobial efficacy of triple antibiotic paste and amoxicillin clavulanate paste as an intracanal medicament against Enterococcus faecalis: An in vitro study.

Background: Triple antibiotic paste (TAP) is the commonly used intracanal medicament against Enterococcus faecalis. Amoxicillin clavulanate paste (ACP) is recommended as a "fall-back" antibiotic when traditional dental antibiotics fail. Literature comparing the antimicrobial efficacy of TAP and ACP in eradicating E. faecalis from the root canal system is sparse; hence, this in vitro study was conducted to evaluate and compare the antimicrobial efficacy of TAP and ACP as an intracanal medicament for endodontic treatment of single-rooted permanent teeth against E. faecalis. Materials and Methods: This in vitro, experimental study evaluated 60 root samples obtained from extracted single-rooted human permanent teeth. The canal diameter was enlarged and subsequently infected with E. faecalis for 21 days. Four groups of the contaminated samples were treated with TAP, ACP, calcium hydroxide (positive control), and saline (negative control), respectively. Dentinal shavings were collected at the end of the 1st, 7th, and 10th day and inoculated in agar plates. The number of colony-forming units was determined, and the data were statistically analyzed using the Kolmogorov-Smirnov and Shapiro-Wilks test. P <0.05 was considered statistically significant. Results: The mean number of E. faecalis colony counts across all 3 test days demonstrated that TAP exhibited the highest inhibition of bacterial growth, followed by ACP which is not statistically significant (P = 1.00). Conclusion: Considering the limitations of this in vitro study, the findings suggest that ACP could be an effective alternative intracanal medicament to TAP for endodontic therapy.

Early switch from intravenous to oral antibiotic therapy in patients with cancer who have low-risk neutropenic sepsis: the EASI-SWITCH RCT.

Background: Neutropenic sepsis is a common complication of systemic anticancer treatment. There is variation in practice in timing of switch to oral antibiotics after commencement of empirical intravenous antibiotic therapy. Objectives: To establish the clinical and cost effectiveness of early switch to oral antibiotics in patients with neutropenic sepsis at low risk of infective complications. Design: A randomised, multicentre, open-label, allocation concealed, non-inferiority trial to establish the clinical and cost effectiveness of early oral switch in comparison to standard care. Setting: Nineteen UK oncology centres. Participants: Patients aged 16 years and over receiving systemic anticancer therapy with fever (≥ 38°C), or symptoms and signs of sepsis, and neutropenia (≤ 1.0 × 109/l) within 24 hours of randomisation, with a Multinational Association for Supportive Care in Cancer score of ≥ 21 and receiving intravenous piperacillin/tazobactam or meropenem for < 24 hours were eligible. Patients with acute leukaemia or stem cell transplant were excluded. Intervention: Early switch to oral ciprofloxacin (750 mg twice daily) and co-amoxiclav (625 mg three times daily) within 12-24 hours of starting intravenous antibiotics to complete 5 days treatment in total. Control was standard care, that is, continuation of intravenous antibiotics for at least 48 hours with ongoing treatment at physician discretion. Main outcome measures: Treatment failure, a composite measure assessed at day 14 based on the following criteria: fever persistence or recurrence within 72 hours of starting intravenous antibiotics; escalation from protocolised antibiotics; critical care support or death. Results: The study was closed early due to under-recruitment with 129 patients recruited; hence, a definitive conclusion regarding non-inferiority cannot be made. Sixty-five patients were randomised to the early switch arm and 64 to the standard care arm with subsequent intention-to-treat and per-protocol analyses including 125 (intervention n = 61 and control n = 64) and 113 (intervention n = 53 and control n = 60) patients, respectively. In the intention-to-treat population the treatment failure rates were 14.1% in the control group and 24.6% in the intervention group, difference = 10.5% (95% confidence interval 0.11 to 0.22). In the per-protocol population the treatment failure rates were 13.3% and 17.7% in control and intervention groups, respectively; difference = 3.7% (95% confidence interval 0.04 to 0.148). Treatment failure predominantly consisted of persistence or recurrence of fever and/or physician-directed escalation from protocolised antibiotics with no critical care admissions or deaths. The median length of stay was shorter in the intervention group and adverse events reported were similar in both groups. Patients, particularly those with care-giving responsibilities, expressed a preference for early switch. However, differences in health-related quality of life and health resource use were small and not statistically significant. Conclusions: Non-inferiority for early oral switch could not be proven due to trial under-recruitment. The findings suggest this may be an acceptable treatment strategy for some patients who can adhere to such a treatment regimen and would prefer a potentially reduced duration of hospitalisation while accepting increased risk of treatment failure resulting in re-admission. Further research should explore tools for patient stratification for low-risk de-escalation or ambulatory pathways including use of biomarkers and/or point-of-care rapid microbiological testing as an adjunct to clinical decision-making tools. This could include application to shorter-duration antimicrobial therapy in line with other antimicrobial stewardship studies. Trial registration: This trial is registered as ISRCTN84288963. Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 13/140/05) and is published in full in Health Technology Assessment; Vol. 28, No. 14. See the NIHR Funding and Awards website for further award information.

Neutropenic sepsis, or infection with a low white blood cell count, can occur following cancer treatment. Usually patients receive treatment with intravenous antibiotics (antibiotics delivered into a vein) for two or more days. Patients at low risk of complications from their infection may be able to have a shorter period of intravenous antibiotics benefitting both patients and the NHS. The trial compared whether changing from intravenous to oral antibiotics (antibiotics taken by mouth as tablets or liquid) 12­24 hours after starting antibiotic treatment ('early switch') is as effective as usual care. Patients could take part if they had started intravenous antibiotics for low-risk neutropenic sepsis. Patients were randomly allocated to 'early switch' or to usual care. The main outcome measured was treatment failure. Treatment failure happened if fever persisted or recurred despite antibiotics, if patients needed to change antibiotics, if they needed to be re-admitted to hospital or needed to be admitted to intensive care within 14 days or died. We had originally intended that 628 patients would take part, but after review of the design of the study the number needed to take part was revised to 230. We were not able to complete the trial as planned as unfortunately only 129 patients took part. As the trial was smaller than expected we were not able to draw conclusions as to whether 'early switch' is no less effective than usual care. Our findings suggest that 'early switch' might result in a shorter time in hospital initially; however, treatment failure was more likely to occur, meaning some patients had to return to hospital for further antibiotics. There were no differences in side effects and no serious complications from treatment or treatment failure (such as intensive care admission or death) among the 65 patients in the 'early switch' group. Patients were satisfied with 'early switch'. Early switch may be a treatment option for some patients with low-risk neutropenic sepsis who would prefer a shorter duration of hospital admission but accept a risk of needing hospital re-admission.

Comprehensive stability analysis of 13 ß-lactams and ß-lactamase inhibitors in in vitro media, and novel supplement dosing strategy to mitigate thermal drug degradation.

Non-clinical antibiotic development relies on in vitro susceptibility and infection model studies. Validating the achievement of the targeted drug concentrations is essential to avoid under-estimation of drug effects and over-estimation of resistance emergence. While certain ß-lactams (e.g., imipenem) and ß-lactamase inhibitors (BLIs; clavulanic acid) are believed to be relatively unstable, limited tangible data on their stability in commonly used in vitro media are known. We aimed to determine the thermal stability of 10 ß-lactams and 3 BLIs via LC-MS/MS in cation-adjusted Mueller Hinton broth at 25 and 36°C as well as agar at 4 and 37°C, and in water at -20, 4, and 25°C. Supplement dosing algorithms were developed to achieve broth concentrations close to their target over 24 h. During incubation in broth (pH 7.25)/agar, degradation half-lives were 16.9/21.8 h for imipenem, 20.7/31.6 h for biapenem, 29.0 h for clavulanic acid (studied in broth only), 23.1/71.6 h for cefsulodin, 40.6/57.9 h for doripenem, 46.5/64.6 h for meropenem, 50.8/97.7 h for cefepime, 61.5/99.5 h for piperacillin, and >120 h for all other compounds. Broth stability decreased at higher pH. All drugs were ≥90% stable for 72 h in agar at 4°C. Degradation half-lives in water at 25°C were >200 h for all drugs except imipenem (14.7 h, at 1,000 mg/L) and doripenem (59.5 h). One imipenem supplement dose allowed concentrations to stay within ±31% of their target concentration. This study provides comprehensive stability data on ß-lactams and BLIs in relevant in vitro media using LC-MS/MS. Future studies are warranted applying these data to antimicrobial susceptibility testing and assessing the impact of ß-lactamase-related degradation.

The pipeline for drugs for control and elimination of neglected tropical diseases: 2. Oral anti-infective drugs and drug combinations for off-label use.

In its 'Road map for neglected tropical diseases 2021-2030', the World Health Organization outlined its targets for control and elimination of neglected tropical diseases (NTDs) and research needed to achieve them. For many NTDs, this includes research for new treatment options for case management and/or preventive chemotherapy. Our review of small-molecule anti-infective drugs recently approved by a stringent regulatory authority (SRA) or in at least Phase 2 clinical development for regulatory approval showed that this pipeline cannot deliver all new treatments needed. WHO guidelines and country policies show that drugs may be recommended for control and elimination for NTDs for which they are not SRA approved (i.e. for 'off-label' use) if efficacy and safety data for the relevant NTD are considered sufficient by WHO and country authorities. Here, we are providing an overview of clinical research in the past 10 years evaluating the anti-infective efficacy of oral small-molecule drugs for NTD(s) for which they are neither SRA approved, nor included in current WHO strategies nor, considering the research sponsors, likely to be registered with a SRA for that NTD, if found to be effective and safe. No such research has been done for yaws, guinea worm, Trypanosoma brucei gambiense human African trypanosomiasis (HAT), rabies, trachoma, visceral leishmaniasis, mycetoma, T. b. rhodesiense HAT, echinococcosis, taeniasis/cysticercosis or scabies. Oral drugs evaluated include sparfloxacin and acedapsone for leprosy; rifampicin, rifapentin and moxifloxacin for onchocerciasis; imatinib and levamisole for loiasis; itraconazole, fluconazole, ketoconazole, posaconazole, ravuconazole and disulfiram for Chagas disease, doxycycline and rifampicin for lymphatic filariasis; arterolane, piperaquine, artesunate, artemether, lumefantrine and mefloquine for schistosomiasis; ivermectin, tribendimidine, pyrantel, oxantel and nitazoxanide for soil-transmitted helminths including strongyloidiasis; chloroquine, ivermectin, balapiravir, ribavirin, celgosivir, UV-4B, ivermectin and doxycycline for dengue; streptomycin, amoxicillin, clavulanate for Buruli ulcer; fluconazole and isavuconazonium for mycoses; clarithromycin and dapsone for cutaneous leishmaniasis; and tribendimidine, albendazole, mebendazole and nitazoxanide for foodborne trematodiasis. Additional paths to identification of new treatment options are needed. One promising path is exploitation of the worldwide experience with 'off-label' treatment of diseases with insufficient treatment options as pursued by the 'CURE ID' initiative.

Clostridioides difficile recovered in pleural fluid: Contamination or infection? A case report of a proven empyema and a literature review / Aislamiento de Clostridioides difficile en líquido pleural: ¿contaminación o infección? Presentación de un caso probado de empiema y revisión de la literatura

Introduction: Pleural empyema is an infrequent manifestation of extraintestinal Clostridioidesdifficile infection, with just eight cases reported in literature. Methods: We report a new case in a 70-year-old male without comorbidities or evidence of concomitant gastrointestinal disease, and review the previous cases reported in the literature. Results: The isolate was susceptible to all antimicrobial tested and was negative for A+B toxins. The patient fully recovered after drainages and antimicrobial therapy with amoxicillin–clavulanate and doxycycline. Conclusion: As in the previously reported cases, aspiration was the most plausible hypothesis of mechanism of infection in our patient. Empyema by Clostridioidesdifficile is a diagnostic challenge, since it is necessary to rule out that the isolation of this microorganism in pleural fluid is not a contamination. Furthermore, more evidence is needed for its treatment since data regarding this entity are still scarce.(AU)

Introducción: El empiema pleural es una manifestación infrecuente de la infección extraintestinal por Clostridioidesdifficile, con sólo ocho casos reportados en la literatura. Métodos: Documentamos un nuevo caso de un varón de 70 años sin comorbilidades ni evidencia de enfermedad gastrointestinal concomitante y revisamos los casos previamente descritos en la literatura. Resultados: El aislado fue sensible a todos los antibióticos testados y fue negativo para las toxinas A+B. El paciente se recuperó totalmente tras la realización de drenajes y terapia antimicrobiana con amoxicilina-clavulánico y doxiciclina. Conclusión: Al igual que en los casos previamente documentados, la broncoaspiración fue la hipótesis más plausible del mecanismo de infección en nuestro paciente. El empiema por Clostridioidesdifficile constituye un reto diagnóstico, ya que es necesario descartar que su aislamiento en líquido pleural no se deba a una contaminación. Además, se necesita más evidencia científica para el tratamiento de esta entidad, ya que los datos sobre la misma aún son escasos.(AU)

Comparative metabolomics reveal key pathways associated with the synergistic activities of aztreonam and clavulanate combination against multidrug-resistant Escherichia coli.

IMPORTANCE: Multidrug-resistant Escherichia coli is a major threat to the health care system and is associated with poor outcomes in infected patients. The combined use of antibiotics has become an important treatment method for multidrug-resistant bacteria. However, the mechanism for their synergism has yet to be explored.

Hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) in Canada: treatment update and the role of new IV antimicrobials.

INTRODUCTION: Hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) continue to be common infections causing significant morbidity and mortality worldwide. The timely initiation of empiric antimicrobial therapy is essential. In this paper, we provide a focused expert opinion on the current and potential empiric antimicrobial treatment options in HABP and VABP in Canada influenced by antimicrobial resistance impacting the use of older agents as well as available new intravenous (IV) antimicrobials. AREAS COVERED: The authors discuss treatment options for HABP and VABP in Canada. In addition, we focus on the potential role of new IV antimicrobials recently introduced to Canada. A literature search of HABP and VABP treatments was performed via PubMed (up to March 2023), using the following key words: monotherapy, combination therapy, aminoglycosides, carbapenems, cephalosporins, fluoroquinolones, penicillins as well as amoxicillin/clavulanate, ceftobiprole, ceftolozane/tazobactam, dalbavancin, and fosfomycin. EXPERT OPINION: Empiric antimicrobial treatment for HABP and VABP in Canada continues to focus on both the severity of illness and the presence/absence of patient risk factors for antimicrobial resistance. The role of new IV antimicrobials in the empiric treatment for HABP and VABP depends on their antimicrobial activity and published data on efficacy and safety and influenced by Health Canada-approved indications.

Amoxicillin-induced aseptic meningitis: clinical features, diagnosis and management.

OBJECTIVES: The clinical features of aseptic meningitis associated with amoxicillin are unknown. The main objective of this study was to investigate the clinical characteristics of amoxicillin-induced aseptic meningitis (AIAM) and provide a reference for clinical diagnosis and treatment. METHODS: AIAM-related studies were collected by searching the relevant databases from inception to October 31, 2022. RESULTS: AIAM usually occurred 3 h to 7 days after amoxicillin administration in 13 males and 9 females. Twenty-one patients (95.5%) had recurrent AIAM with a total of 62 episodes. Fever (19 cases, 86.4%) and headache (18 cases, 81.8%) were the most common symptoms. Typical cerebrospinal fluid (CSF) findings were leukocytosis (100%) with lymphocytic predominance (14 cases, 63.6%), elevated protein (20 cases, 90.1%), normal glucose (21 cases, 95.5%) and negative culture (21 cases, 100%). Brain magnetic resonance imaging showed mild meningeal enhancement in one patient. The symptoms resolved mainly within 1-4 days after drug discontinuation in all patients. CONCLUSION: Clinical attention should be given to the adverse effects of AIAM. The medication history of patients with suspected meningitis should be investigated to avoid unnecessary examination and antibiotic treatment.

Antibiotic treatment failure of uncomplicated urinary tract infections in primary care.

BACKGROUND: Higher resistance rates of > 20% have been noted in Enterobacteriaceae urinary isolates towards ciprofloxacin and co-trimoxazole (C + C) in Singapore, compared with amoxicillin-clavulanate and nitrofurantoin (AC + N). This study examined if treatment failure varied between different antibiotics, given different resistant rates, for uncomplicated urinary tract infections (UTIs) managed in primary care. We also aimed to identify gaps for improvement in diagnosis, investigations, and management. METHODS: A retrospective cohort study was conducted from 2019 to 2021 on female patients aged 18-50 with uncomplicated UTIs at 6 primary care clinics in Singapore. ORENUC classification was used to exclude complicated UTIs. Patients with uncomplicated UTIs empirically treated with amoxicillin-clavulanate, nitrofurantoin, ciprofloxacin or co-trimoxazole were followed-up for 28 days. Treatment failure was defined as re-attendance for symptoms and antibiotic re-prescription, or hospitalisation for UTI complications. After 2:1 propensity score matching in each group, modified Poisson regression and Cox proportional hazard regression accounting for matched data were used to determine risk and time to treatment failure. RESULTS: 3194 of 4253 (75.1%) UTIs seen were uncomplicated, of which only 26% were diagnosed clinically. Urine cultures were conducted for 1094 (34.3%) uncomplicated UTIs, of which only 410 (37.5%) had bacterial growth. The most common organism found to cause uncomplicated UTIs was Escherichia coli (64.6%), with 92.6% and 99.4% of isolates sensitive to amoxicillin-clavulanate and nitrofurantoin respectively. Treatment failure occurred in 146 patients (4.57%). Among 1894 patients treated with AC + N matched to 947 patients treated with C + C, patients treated with C + C were 50% more likely to fail treatment (RR 1.49, 95% CI 1.10-2.01), with significantly higher risk of experiencing shorter time to failure (HR 1.61, 95% CI 1.12-2.33), compared to patients treated with AC + N. CONCLUSION: Treatment failure rate was lower for antibiotics with lower reported resistance rates (AC + N). We recommend treating uncomplicated UTIs in Singapore with amoxicillin-clavulanate or nitrofurantoin, based on current local antibiograms. Diagnosis, investigations and management of UTIs remained sub-optimal. Future studies should be based on updating antibiograms, highlighting its importance in guideline development.

Phenotypic and genomic characteristics of oxacillin-susceptible mecA-positive Staphylococcus aureus, rapid selection of high-level resistance to beta-lactams.

The aim of this study is to describe the phenotypic and genetic properties of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) isolates and their beta-lactam resistant derivatives obtained after selection with oxacillin. A collection of hospital- (HA-) and community-acquired (CA-) MRSA was screened for oxacillin susceptibility. Antibiotic susceptibility testing, population analysis profile (PAP), mecA expression analysis, and whole genome sequencing (WGS) were performed for 60 mecA-positive OS-MRSA isolates. Twelve high-level beta-lactam resistant derivatives selected during PAP were also subjected to WGS. OS-MRSA were more prevalent among CA-MRSA (49/205, 24%) than among HA-MRSA (11/575, 2%). OS-MRSA isolates belonged to twelve sequence types (ST), with a predominance of ST22-t223-SCCmec IVc and ST59-t1950-SCCmec V lineages. OS-MRSA were characterized by mecA promoter mutations at - 33 (C→T) or - 7 (G→T/A) along with PBP2a substitutions (S225R or E246G). The basal and oxacillin-induced levels of mecA expression in OS-MRSA isolates were significantly lower than those in control ST8-HA-MRSA isolates. Most of the OS-MRSA isolates were heteroresistant to oxacillin. High-level beta-lactam resistant OS-MRSA derivatives selected with oxacillin carried mutations in mecA auxiliary factors: relA (metabolism of purines), tyrS, cysS (metabolism of tRNAs), aroK, cysE (metabolism of amino acids and glycolysis). Cefoxitin-based tests demonstrated high specificity for OS-MRSA detection. The highest positive predictive values (PPV > 0.95) were observed for broth microdilution, the VITEK® 2 automatic system, and chromogenic media. Susceptibility testing of CA-MRSA requires special attention due to the high prevalence of difficult-to-detect OS-MRSA among them. Mis-prescription of beta-lactams for the treatment of OS-MRSA may lead to selection of high-level resistance and treatment failures.

National Amoxicillin-Clavulanate Formulation Use Pattern: A Survey.

OBJECTIVE: Five commercially available amoxicillin-clavulanate (AMC) ratio formulations contribute to ratio selection variability with efficacy and toxicity implications. The objective of this survey was to determine AMC formulation use patterns across the United States. METHODS: A multicenter practitioner survey was distributed to multiple listservs (American College of Clinical Pharmacy pediatrics, infectious diseases, ambulatory care, pharmacy administration; American Society of Health-System Pharmacists; Pediatric Pharmacy Association members), and selected pediatric Vizient members in June 2019. Responses were screened for multiples within institutions. Repeated organization responses were identified (n = 37) and excluded if the duplicate matched another response from the same organization exactly (n = 0). RESULTS: One hundred ninety independent responses were received. Nearly 62% of respondents represented a children's hospital within an acute care hospital; remainder being from stand-alone children's hospitals. Around 55% of respondents indicated prescribers were responsible for choosing the patient-specific formulation for inpatients. Nearly 70% of respondents indicated multiple formulations were available due to clinical need (efficacy, toxicity, measurable volume), whereas over 40% responded that the number of liquid formulations were limited to decrease the potential for error. Variability was demonstrated among institutions using ≥ 2 different formulations for acute otitis media (AOM), sinusitis, lower respiratory tract infection, skin and soft tissue infection, and urinary tract infection (33.6%, 37.3%, 41.5%, 35.8%, and 35.8%, respectively). The 14:1 formulation was the most common, but not exclusive, for AOM, sinusitis, and lower respiratory tract infections with 2.1%, 2.1%, and 2.6% of respondents indicating use of the 2:1 formulation and 10.9%, 15%, and 16.6% of respondents indicating use of the 4:1 formulation. CONCLUSIONS: Significant AMC formulation selection variability exists across the United States.

Diagnostic Dilemma in a Case of Necrotizing Pneumonia With Negative Transbronchial Biopsy.

A 33-year-old male with a past medical history of asthma presented to the Emergency room with a three-day history of right-sided chest pain, productive cough with dark brown sputum, and shortness of breath. He was found to have right lower lobe consolidation consistent with acute pneumonia, and areas of non-homogenous density within the consolidation, suspicious of necrotizing pneumonia. Computed tomography (CT) of the chest with IV contrast revealed a large, irregular thick-walled cavitary mass involving the right middle lobe with surrounding ground glass cavitation. An extensive workup was negative, including a transbronchial biopsy. The case explains how a causative organism was detected.

Evaluation of Phenotypic Tests to Detect Extended-Spectrum ß-Lactamase (ESBL)-Producing Klebsiella oxytoca Complex Strains.

Klebsiella oxytoca complex (KoC) species may overproduce their chromosomal class A OXY ß-lactamases, conferring reduced susceptibility to piperacillin-tazobactam, expanded-spectrum cephalosporins and aztreonam. Moreover, since clavulanate maintains its ability to inhibit these enzymes, the resulting resistance phenotype may falsely resemble the production of acquired extended-spectrum ß-lactamases (ESBLs). In this work, a collection of 44 KoC strains of human and animal origin was characterized with whole-genome sequencing (WGS) and broth microdilution (BMD) susceptibility testing. Comparison of ESBL producers (n = 11; including CTX-M-15 [n = 6] and CTX-M-1 [n = 5] producers) and hyperproducers of OXYs (n = 21) showed certain phenotypic differences: piperacillin-tazobactam (MIC90s: 16 versus >64 µg/mL), cefotaxime (MIC90s: 64 versus 4 µg/mL), ceftazidime (MIC90s: 32 versus 4 µg/mL), cefepime (MIC90s: 8 versus 4 µg/mL) and associated resistance to non-ß-lactams (e.g., trimethoprim-sulfamethoxazole: 90.9% versus 14.3%, respectively). However, a clear phenotype-based distinction between the two groups was difficult. Therefore, we evaluated 10 different inhibitor-based confirmatory tests to allow such categorization. All tests showed a sensitivity of 100%. However, only combination disk tests (CDTs) with cefepime/cefepime-clavulanate and ceftazidime/ceftazidime-clavulanate or the double-disk synergy test (DDST) showed high specificity (100%, 95.5%, and 100%, respectively). All confirmatory tests in BMD or using the MIC gradient strip did not perform well (specificity, ≤87.5%). Of note, ceftazidime/ceftazidime-avibactam tests also exhibited low specificity (CDT, 87.5%; MIC gradient strip, 77.8%). Our results indicate that standard antimicrobial susceptibility profiles can raise some suspicion, but only the use of cefepime/cefepime-clavulanate CDT or DDST can guarantee distinction between ESBL-producing KoC strains and those hyperproducing OXY enzymes.

Antibiotic associated diarrhea in outpatient pediatric antibiotic therapy.

BACKGROUND: Antibiotic-associated diarrhea is one of the most frequent side effects of antimicrobial therapy. We assessed the epidemiological data of antibiotic-associated diarrhea in pediatric patients in our region. METHODS: The prospective multi-center study included pediatric patients who were initiated an oral antibiotic course in outpatient clinics and followed in a well-established surveillance system. This follow-up system constituded inclusion of patient by the primary physician, supply of family follow-up charts to the family, passing the demographics and clinical information of patient to the Primary Investigator Centre, and a close telephone follow-up of patients for a period of eight weeks by the Primary Investigator Centre. RESULTS: A result of 758 cases were recruited in the analysis which had a frequency of 10.4% antibiotic-associated diarrhea. Among the cases treated with amoxicillin-clavulanate 10.4%, and cephalosporins 14.4% presented with antibiotic-associated diarrhea. In the analysis of antibiotic-associated diarrhea occurrence according to different geographical regions of Turkey, antibiotic-associated diarrhea episodes differed significantly (p = 0.014), particularly higher in The Eastern Anatolia and Southeastern Anatolia. Though most commonly encountered with cephalosporin use, antibiotic-associated diarrhea is not a frequent side effect. CONCLUSION: This study on pediatric antibiotic-associated diarrhea displayed epidemiological data and the differences geographically in our region.

Repurposing ß-Lactams for the Treatment of Mycobacterium kansasii Infections: An In Vitro Study.

Mycobacterium kansasii (Mkn) causes tuberculosis-like lung infection in both immunocompetent and immunocompromised patients. Current standard therapy against Mkn infection is lengthy and difficult to adhere to. Although ß-lactams are the most important class of antibiotics, representing 65% of the global antibiotic market, they have been traditionally dismissed for the treatment of mycobacterial infections, as they were considered inactive against mycobacteria. A renewed interest in ß-lactams as antimycobacterial agents has shown their activity against several mycobacterial species, including M. tuberculosis, M. ulcerans or M. abscessus; however, information against Mkn is lacking. In this study, we determined the in vitro activity of several ß-lactams against Mkn. A selection of 32 agents including all ß-lactam chemical classes (penicillins, cephalosporins, carbapenems and monobactams) with three ß-lactamase inhibitors (clavulanate, tazobactam and avibactam) were evaluated against 22 Mkn strains by MIC assays. Penicillins plus clavulanate and first- and third-generation cephalosporins were the most active ß-lactams against Mkn. Combinatorial time-kill assays revealed favorable interactions of amoxicillin-clavulanate and cefadroxil with first-line Mkn treatment. Amoxicillin-clavulanate and cefadroxil are oral medications that are readily available, and well tolerated with an excellent safety and pharmacokinetic profile that could constitute a promising alternative option for Mkn therapy.

VRE acquisition in hospital and its association with hospital antimicrobial usage -a non-linear analysis of an extended time series.

BACKGROUND: Vancomycin resistant enterococci (VRE) have become endemic pathogens in many Australian hospitals causing significant morbidity. There are few observational studies that have evaluated the effect of antibiotic usage on VRE acquisition. This study examined VRE acquisition and its association with antimicrobial use. The setting was a NSW tertiary hospital with 800 beds over a 63 month period up to March 2020, straddling piperacillin-tazobactam (PT) shortages that occurred from in September 2017. METHODS: The primary outcome was monthly inpatient hospital onset Vancomycin-resistant Enterococci (VRE) acquisitions. Multivariate adaptive regression splines (MARS) were used to estimate hypothetical thresholds, where antimicrobial use above threshold is associated with increased incidence of hospital onset VRE acquisition. Specific antimicrobials and categorised usage (broad, less broad and narrow spectrum) were modelled. RESULTS: There were 846 hospital onset VRE detections over the study period. Hospital onset vanB and vanA VRE acquisitions fell significantly by 64% and 36% respectively after the PT shortage. MARS modelling indicated that PT usage was the only antibiotic found to exhibit a meaningful threshold. PT usage greater than 17.4 defined daily doses/1000 occupied bed-days (95%C I: 13.4, 20.5) was associated with higher onset of hospital VRE. CONCLUSIONS: This paper highlights the large, sustained impact that reduced broad spectrum antimicrobial use had on VRE acquisition and showed that PT use in particular was a major driver with a relatively low threshold. It raises the question as to whether hospitals should be determining local antimicrobial usage targets based on direct evidence from local data analysed with non-linear methods.