Antibiotic Susceptibility Test Results Research Articles

Determination rates of antibiotic resistance, inducible beta-lactamase, and metallo beta-lactamase ratios in Pseudomonas aeruginosa isolates in a university hospital in Turkey

Objective: This study aimed to determine the antibiotic resistance, inducible beta-lactamase (IBL), and Metallo beta-lactamase (MBL) rates in P. aeruginosa isolates.
 Material and Methods: In our study, 100 P. aeruginosa isolates obtained from various clinical samples were used. Antibiotic susceptibility was performed by using the Kirby-Bauer disk diffusion method. Carbapenem resistance to imipenem and meropenem was verified by the E test. The disk induction method was used to determine the IBL production while the Modified Hodge test, MBL E test, and combined imipenem/ EDTA disk were used to determine the production of MBL.
 Results: According to the results of antibiotic susceptibility tests, 58% of P. aeruginosa isolates were susceptible to all antipseudomonal drugs, while resistance rates to other drugs were as follows; ceftazidime 7%, cefoperazone sulbactam 8%, cefepime 13%, piperacillin 14%, piperacillin-tazobactam 12%, imipenem 9%, meropenem 11%, aztreonam 8%, amikacin 8%, gentamicin 13%, tobramycin 12%, netilmicin 19%, There was a 10% resistance to ciprofloxacin. 8% of the isolates were resistant to at least three drugs, of which two isolates were positive for MBL enzyme production. IBL production was detected in 86% of the isolates with the disk induction method.
 Conclusion: The results we obtained in our study are consistent with other researchers globally and in Turkey. It was concluded that there is a need for well-standardized phenotypic tests with defined evaluation criteria and further studies to verify these tests genotypically.

Antibiotics Susceptibility Pattern in Diabetic Ulcer Patients

Diabetic ulcers are a chronic complication of diabetes mellitus and have a high risk of infection. Severe ulcer infectionsare a significant cause of lower-extremity amputations in addition to trauma. Therefore, therapy for diabetic ulcer infectionsmust be performed immediately. This study aimed to determine the bacterial susceptibility pattern to the antibiotic indiabetic ulcer patients. This study was retrospective observational descriptive by taking the results of swab culture andantibiotic susceptibility patterns data in diabetic ulcer patients at Ulin General Hospital, Banjarmasin, in 2016-2018. Theresults showed 41 (62.1%) monomicrobial infections and 25 (37.9%) polymicrobial infections. The number of Gram-negativebacilli (57.4%) was higher than Gram-positive cocci (42.6%). The most common bacterial isolates on pus culture wereStaphylococcus aureus (26.6%), Klebsiella pneumonia (19.1%), and Escherichia coli (12.8%). Antibiotic susceptibility testresults showed that Gram-positive bacteria were sensitive to Tigecycline (100%), Nitrofurantoin (96.9%), and Linezolid(96.8%). Gram-negative bacteria were susceptible to Ertapenem (92.7%), Meropenem, and Amikacin (90.6%). S.aureusisolates were sensitive 100% to Meropenem and Tigecycline. K.peneumoniae and E.coli isolates were susceptible 100% toMeropenem and Amikacin. It was concluded in this study that the prevalence of Gram-negative bacteria in diabetic ulcerinfection was higher than Gram-positive bacteria. The most common isolated Gram-negative bacteria were K.pneumoniaeand E.coli, while the most common Gram-positive bacteria were S.aureus. The most sensitive antibiotics for K.pneumoniaeand E.coli were Meropenem and Amikacin, while the most sensitive antibiotics for S.aureus were Linezolid and Tigecycline.

The distribution of microorganisms and antibiotic resistance profile in pulmonary critical care unit patients: A single-centre study

The patients in the intensive care unit have a higher risk of infections because of the poor general condition of these patients and the frequent application of invasive procedures with longer hospitalization length. Also, this group of patients tend to have resistant infections due to empirically widespread and uncontrolled use of broad-spectrum antibiotics. Hence, data are needed to determine appropriate empirical antibiotic therapy in intensive care patients. In this study, it was aimed to assess the distribution of microorganisms and antibiotic resistance profile from the samples taken from the patients in the intensive care unit. Patients who were hospitalized in Ankara University Faculty of Medicine Chest Diseases Intensive Care Unit for more than 24 hours between December 2016 and December 2017 were included in our study. Demographic characteristics, comorbid diseases, clinical findings, results of sputum, tracheal aspirate, blood, urine, gaita and pus culture samples and antibiotic susceptibility test results were recorded prospectively. A total of 287 patients, 150 males and 137 females, were included in the study. The mean age of all patients was 69.96 ± 14.4 years. Two hundred twenty-three positive cultures were detected in 1053 samples taken from 287 patients. Gram-negative bacilli constituted 55.1% of the 223 positive cultures. The most common microorganisms were Acinetobacter (16.6%), Staphylococcus (14.8%) and Klebsiella (10.8%). Colistin resistance was found to be 8.3% in the Acinetobacter strains and resistance rates of 97-100% were observed to other antibiotic groups. Thirty-three staphylococcus were isolated, 17 were S. aureus and 16 were coagulase-negative Staphylococcus. While 29.4% of S. aureus were resistant to methicillin (MRSA), vancomycin resistance was not detected. Meanwhile, the MRSA ratio was 62.5%, there was no vancomycin resistance among the coagulase-negative Staphylococcus. Klebsiella was the third most common microorganism and beta-lactamase producing Klebsiella strain was 62.5%. Gentamycin was found to be the most susceptible antibiotic in Klebsiella strains with a resistance rate of 20.8%. Pseudomonas aeruginosa constituted 9.4% of the cultures. While the resistance to colistin was not detected, resistance to piperacillin/tazobactam 42.8%, tobramycin, imipenem and meropenem 50% and ceftazidime 61.9%. The duration of hospitalization in patients with Acinetobacter isolated (23 [10-34] days vs 12.5 [5-24] days, p= 0.011) and the mortality rate (62.5% vs 37.5%, p= 0.008) were significantly higher than those who were not Acinetobacter isolated. In conclusion, gram-negative bacilli constitute the majority of the patients in intensive care unit. Acinetobacter, the most common microorganism, has a high resistance rate and has been associated with prolonged hospitalization and mortality.

Infectious Diseases Society of America Guidance on the Treatment of Extended-Spectrum β-lactamase Producing Enterobacterales (ESBL-E), Carbapenem-Resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with Difficult-to-Treat Resistance (DTR-P. aeruginosa).

Antimicrobial-resistant infections are commonly encountered in US hospitals and result in significant morbidity and mortality. This guidance document provides recommendations for the treatment of infections caused by extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with difficult-to-treat resistance (DTR-P. aeruginosa). A panel of 6 infectious diseases specialists with expertise in managing antimicrobial-resistant infections formulated common questions regarding the treatment of ESBL-E, CRE, and DTR-P. aeruginosa infections. Based on review of the published literature and clinical experience, the panel provide recommendations and associated rationale for each recommendation. Because of significant differences in the molecular epidemiology of resistance and the availability of specific anti-infective agents globally, this document focuses on treatment of antimicrobial-resistant infections in the United States. Approaches to empiric treatment selection, duration of therapy, and other management considerations are briefly discussed. The majority of guidance focuses on preferred and alternative treatment recommendations for antimicrobial-resistant infections, assuming that the causative organism has been identified and antibiotic susceptibility testing results are known. Treatment recommendations apply to both adults and children. The field of antimicrobial resistance is dynamic and rapidly evolving, and the treatment of antimicrobial-resistant infections will continue to challenge clinicians. This guidance document is current as of 17 September 2020. Updates to this guidance document will occur periodically as new data emerge. Furthermore, the panel will expand recommendations to include other problematic gram-negative pathogens in future versions. The most current version of the guidance including the date of publication can be found at www.idsociety.org/practice-guideline/amr-guidance/.

Antibiogram of Pseudomonas species: an important tool to combat antibiotic resistance for patient safety in Gombe, Nigeria

Background: Pseudomonas species are responsible for different healthcare-associated infections and are inherently resistant to many commonly used antibiotics. Hospital antibiograms are either absent or not regularly available in most healthcare facilities in Nigeria. The objective of this study is to present the antibiogram of Pseudomonas isolates in Federal Teaching Hospital Gombe (FTHG) in order to guide antibiotic prescription for better patient safety in the hospital.Methodology: The is a hospital-based cross-sectional study. A total of 4309 bacterial isolates were recovered from aerobic cultures of routine clinical specimens including urine, sputum, blood, swabs, aspirates, biopsies, seminal fluids and cerebrospinal fluids at the Medical Microbiology laboratory of the hospital between January and December 2019. Pseudomonas species were identified by colony morphology, Gram-reaction and conventional biochemical tests. Antibiotic susceptibility testing was performed on each Pseudomonas isolate using the modified Kirby-Bauer disk diffusion method on Mueller-Hinton agar and results interpreted according to the guideline of the Clinical and Laboratory Standards Institute (CLSI). Data were analysed using the Statistical Package for Social Sciences (SPSSTM) software version 23.0.Results: Of the total 4309 bacterial isolates, 436 (10.1%) Pseudomonas species were identified, with majority (49.8%) from urine specimens. Antibiotic susceptibility test results revealed average susceptibility rates of 73.8%, 70.1%, 66.2%, 59.5%, and 34.3% to ciprofloxacin, gentamicin, levofloxacin ceftazidime, and carbenicillin respectively. These rates fluctuate only slightly for each of the antibiotic during the 12 months period of survey.Conclusion: Pseudomonas species were most sensitive to ciprofloxacin and gentamicin among the first line antibiotics in FTHG in 2019. Regular updates and presentation of hospital antibiogram especially for intrinsically resistant bacteria such as Pseudomonas involved in healthcare associated infections, is an important tool in combating antimicrobial resistance and ensuring patient safety.
 Keywords: antibiogram, Pseudomonas, antimicrobial resistance, antimicrobial stewardship, patient safety

Study the Effect of Ultraviolet (UV) on Mutagenicity of Pseudomonas Aeruginosa Isolated from Burn Wound Infections

Burn wound infections are regarded as one of the serious complications occurs in the acute period afterinjury and leads to high morbidity and mortality. Pseudomonas aeruginosa plays a prominent role as anetiological agent involved in serious infections of burn and wounds.During this study, a total of (52) samples were taken from patients suffering from burn wound infectionsin (2) hospital in Baghdad from 1/9/2019 to 1/12/2019 for isolation of pseudomonas aeruginosa. Resultsreveals that (31) isolate (59.6%) were gave typical morphological characteristics and biochemical test thatrelated to Pseudomonas aeruginosa. Five Pseudomonas aeruginosa isolates were subject to antimicrobialsusceptibility test that was done according to NCCLS. Results of Antibiotic susceptibility test for pseudomonasaeruginosa isolates reveals that 100% of them were sensitive to ciprofloxacin and Norfloxacin while 100%of the isolates were resistant to ampicillin ,cefixime ,Erythromycin, Naldixic acid , chloramphenicol andbacitracin.Mutagenesis of Pseudomonas aeruginosa PS1 isolate by UV irradiation was done for (60,120,240,300 ) Sec.Results of mutation to ( PS1) isolate revealed that exposure to UV irradiation from (60-300) Sec leads to decreasein the viability of bacterial cells but increase in the sensitivity of PS1 isolate to ciprofloxacin,gentamycine,Norfloxacin and oxytetracycline that reach to (40,21,26,30 )mm zone of inhibition respectively . Thesame isolate revealed changes in results from resistant to sensitive to chloromphenicol ,Erythromycin andNaldixic acid that reach to (33,31,33)mm zone of inhibition respectively but its gave the same results for theantibiotics (Ampicillin,Bacitracin and cefixime).

Distribution of multidrug-resistant Salmonella spp. recovered from aquatic environment of Banda Aceh, Indonesia

Abstract. Suhartono S, Ismail YS, Aini Z. 2021. Distribution of multidrug-resistant Salmonella spp. recovered from aquatic environment of Banda Aceh, Indonesia. Biodiversitas 22: 881-886. The occurrence of pathogenic bacteria in an aquatic system might increase waterborne infections including salmonellosis. This might raise a concern related to the increasing pathogenic bacteria, including the multidrug-resistant Salmonella spp. in the two major rivers, namely Lamnyong and Krueng Aceh crossing the city of Banda Aceh, Indonesia. The objectives of the present study were to isolate and enumerate Salmonella spp. recovered from aquatic environment in Banda Aceh and to determine their antibiotic susceptibility. Bacterial enumeration was performed using most probable number (MPN) method followed by bacterial isolations using selective media Salmonella-Shigella Agar (SSA); whereas, antibiotic susceptibility test was conducted using a procedure as recommended by the National Committee for Clinical Laboratory Standards. There was no significant Salmonella spp. densities/mL of both locations (p = 0.200) although, on average there was about 441.67 Salmonella spp. MPN/mL in Krueng Aceh as opposed to 20.47 MPN/mL of Lamnyong river. There were 57 Salmonella spp. isolates recovered in the sampling sites, i.e. 38 isolates of Lamnyong and 19 isolates of Krueng Aceh. The results of antibiotic susceptibility tests showed that Salmonella spp. isolates recovered from Lamnyong and Krueng Aceh showed antibiotic resistance to azithromycin, tetracycline, and streptomycin. Moreover, Salmonella spp. isolates also showed high resistance to ofloxacin, ciprofloxacin, dan ceftriaxone. All Salmonella spp. isolates were classified as MDR with the number of isolates resistant to 4-6 antibiotics was 33 (57.9%), whereas those that were resistant to 7-9 antibiotics and over 10 antibiotics were 23 (40.4%%) and 5 (8.8%) respectively. The prevalence of MDR Salmonella spp. in the current study suggest that river remain the major reservoirs for the transmission of the pathogen in aquatic systems. An appropriate assessment and monitoring are necessary to reduce the potential health risks and to ensure water quality in the aquatic environment.

Microbiological pattern of prosthetic hip and knee infections: a high-volume, single-centre experience in China.

Introduction. Prosthetic joint infection (PJI) is a serious complication after arthroplasty, which results in high morbidity, prolonged treatment and considerable healthcare expenses in the absence of accurate diagnosis. In China, microbiological data on PJIs are still scarce.Hypothesis/Gap Statement. The incidence of PJI is increasing year by year, and the proportion of drug-resistant bacteria infection is nicreasing, which brings severe challenges to the treatment of infection.Aim. This study aimed to identify the pathogens in PJIs, multi-drug resistance, and evaluate the effect of the treatment regimen in patients with PJI.Methodology. A total of 366 consecutive cases of PJI in the hip or knee joint were admitted at the Orthopedic Surgery Center in Zhengzhou, China from January 2012 to December 2018. Infections were confirmed in accordance with the Infectious Diseases Society of America and the Musculoskeletal Infection Society (MSIS) criteria. Concurrently, patient demographic data, incidence and antibiotic resistance were investigated. Statistical differences were analysed using Fisher's exact test or chi-square test.Results. Altogether, 318 PJI cases satisfying the inclusion criteria were enrolled in this study, including 148 with hip PJIs and 170 with knee PJIs. The average age of patients with hip PJIs was lesser than that of patients with knee PJIs (56.4 vs. 68.6 years). Meanwhile, coagulase-negative staphylococcus (CNS, n=81, 25.5 %) was the predominant causative pathogen, followed by Staphylococcus aureus (n=67, 21.1 %). Methicillin-resistant Staphylococcus (MRS) was identified in 28.9 % of PJI patients. In addition, fungus accounted for 4.8 % (n=15), non-tuberculosis mycobacterium accounted for 1.6 % (n=5), polymicrobial pathogens accounted for 21.7 % (n=69), and Gram-negative bacteria accounted for 7.9 % (n=25) of the total infections. The results of antibiotic susceptibility testing showed that gentamicin and clindamycin β-lactam antibiotics were poorly susceptible to Gram-positive isolates, but they were sensitive to rifampicin, linezolid and vancomycin. While antibiotics such as amikacin and imipenem were effective against Gram-negative bacteria, there was a high resistance rate of other pathogens to gentamicin, clindamycin and some quinolone antibacterial drugs. Empirical antibiotic treatment should combine vancomycin and cephalosporin, levofloxacin or clindamycin. When the pathogen is confirmed, the treatment should be individualized.Conclusions. The prevalence of culture-negative PJIs is still very high. Gram-positive bacteria are still the main type of pathogens that cause PJIs. Attention should be paid to the high incidence of MRS, such as MRSA and MR-CNS, among PJI patients. Empirical antibiotic treatment should cover Gram-positive isolates, especially Staphylococcus.

Impact of urinary selective antibiogram in primary care

ABSTRACT INTRODUCTION: Selective reporting of antibiotic susceptibility test results (selective antibiogram), is increasingly recognized as one of the key strategies of antibiotic stewardship programs. The objective of this study is to determine the impact of selective susceptibility reporting on ciprofloxacin utilization and Escherichia coli susceptibility to ciprofloxacin in the outpatient setting. MATERIAL AND METHODS: A selective reporting policy was created and implemented in 2011. The policy involves the non-reporting of ciprofloxacin susceptibility to Enterobacteriaceae isolated in a urine sample when there was susceptibility to other agents with narrow spectrum. The outcomes evaluated were outpatient ciprofloxacin utilization and E. coli susceptibility to ciprofloxacin between January 2011 and December 2018 RESULTS: Between 2011 and 2018 we detected an increased susceptibility rate of E. coli to ciprofloxacin from 79% to 87% (p < 0.001) and a decreased incidence rate of E. coli resistant to ciprofloxacin from 2.52 to 0.87 (p < 0.001). The ciprofloxacin dropped from 0.75 defined daily doses (DHD) to 0.36 DHD and there was a compensatory increase in nitrofurantoin and fosfomycin utilization. DISCUSSION: Our study showed that selective reporting can influence prescribing practice in a community level and encourages clinicians to select more narrow-spectrum and cost-effective antimicrobial agents in UTIs. CONCLUSION: Our results suggest that selective antibiogram should be considered an effective prevention strategy to reduce targeted antimicrobial utilization.

Bacterial Cross-Contamination in a Veterinary Ophthalmology Setting.

The present study describes the prevalence of bacterial cross-contamination in a veterinary ophthalmology setting, a serious issue that can result in healthcare-associated (or nosocomial) infections among patients and staff. Retrospective (n = 5 patients) and prospective (n = 23 patients) studies evaluated bacterial isolates in companion animals presenting with ulcerative keratitis, sampling the patients' cornea and surrounding examination room, including the environment (exam table, countertop, floor) and ophthalmic equipment (slit lamp, transilluminator, direct ophthalmoscope, indirect headset, tonometer). Results of bacterial culture and antibiotic susceptibility testing were recorded, and degree of genetic relatedness was evaluated in six pairs of isolates (cornea + environment or equipment) using pulse-field gel electrophoresis (PFGE). Overall contamination rate of ophthalmic equipment, environment, and examination rooms (equipment + environment) was 42.9% (15/35 samples), 23.7% (9/38 samples) and 32.9% (24/73 samples), respectively. Methicillin-resistant Staphylococcus pseudintermedius (MRSP), a multi-drug resistant (MDR) pathogen with zoonotic potential, was isolated in 8.2% (6/73) of samples. The patient's cornea was likely the source of cross-contamination in 50% (3/6) of MRSP pairs as evaluated by PFGE; notably, two of the three similar bacterial strains did not have an exact match of their antibiotic susceptibility profiles, highlighting the importance of advanced diagnostics such as PFGE to assess cross-contamination in healthcare facilities. Future work could examine the contamination prevalence of specific equipment or the efficacy of cleaning protocols to mitigate cross-contamination in veterinary practice.

Microbiological profile of chronic suppurative otitis media among patients attending outpatient clinics at alexandria main university hospital, Egypt

Background: Chronic suppurative otitis media (CSOM) is a major public health problem in Egypt and one of the most common diseases of the ear for all age groups. The prevalence and antibiogram of microorganisms associated with CSOM have been reported to vary with time and geographical area probably due to indiscriminate use of antibiotics. Prompt appropriate antimicrobial therapy can effectively reverse the disease process, thereby preventing long term sequels. Hence, the periodic update of the prevalence and antibiogram of the etiological agents for CSOM would be helpful in management of patients. Methods and materials: A cross-sectional study was conducted on 143 patients with active CSOM attending the outpatient clinics of the Otorhinolaryngology Department at Alexandria Main University Hospital (AMUH) over a period of one year from September 2017 to August 2018. Ear discharge samples were aseptically collected using sterile cotton swabs and analyzed by the standard microbiological procedures. Data were analyzed using SPSS (Statistical Package for Social Science) version 21 software. Results: Pathogens were isolated from 95.00% of samples with a total of 153 isolates. Pseudomonas aeruginosa (24.83%), Staphylococcus aureus (S. aureus) (22.22%) and Proteus mirabilis and coagulase-negative staphylococci (13.07% each) were the dominant bacterial isolates. Anaerobes represented only 1.31% of the bacterial isolates and comprised of Peptostreptococcus and Bacteroides spp. Fungi were isolated from 14.38% of samples and comprised of Aspergillus flavus (45.83%), Aspergillus niger (25.00%), Candida albicans and non-albicans Candida (12.50% each) and Penicillium spp. (4.17%). Half of S. aureus isolates (50.00%) were methicillin-resistant S. aureus (MRSA), while 3 (8.82%) were vancomycin-resistant S. aureus (VRSA). Seventy-one (46.41%) aerobic bacterial isolates were multi-drug resistant (MDR), while 6 (3.92%) were pan-drug resistant (PDR). Only 50.33% of aerobic bacterial isolates were sensitive to ciprofloxacin which is the standard antibiotic prescribed by physicians at the outpatient clinics at AMUH. Conclusion: The most common causes of the studied CSOM infections were Pseudomonas aeruginosa and S. aureus.Treatment of CSOM should be based on results of culture and antibiotic susceptibility tests instead of empirical treatment to avoid emergence of MDR and PDR bacteria. Fungal culture should be considered in CSOM, since fungal infection can occur without specific signs and symptoms.

Selective reporting of antibiotic susceptibility testing results: less is more

This Commentary discusses the finding of a study recently published in CMI (Langford B, Daneman N, Diong C, Marchand-Austin A, Adomako K, Saedi A, et al. Antibiotic Susceptibility Reporting and Association with Antibiotic Prescribing: A Cohort Study). It also discusses the available evidence on selective reporting of antibiotic susceptibility testing results, especially on the following topics: What is selective reporting and its forms ? What are the aims we want to achieve with selective reporting ? What is the evidence that it can achieve these aims ? Is there potential harm to the patient, and what is the evidence that this occurs or not ? Potential role of ESCMID and EUCAST ?

Prevalence of Campylobacter Species in Diarrheal Samples of Children Less than 10 Years

Introduction: Campylobacter spp. is one of the most common causes of diarrheal diseases all over theworld, with a rapid acquisition of antibiotic resistance.Objective: Detect the frequency of Campylobacter species in diarrheal stool of children under ten years byconventional and molecular methods, and detect the bacterial ability to produce biofilm.Methods: A total of 200 children presented with diarrhea had been enrolled in this study. Campylobacterwas isolated and diagnosed primarily by characteristic features on Gram stain, culture media, biochemicaltests, and tested against 13 antibiotics by disc diffusion method. The ability of biofilm production wastested by crystal violet quantitative ELISA microtiter plate assays. Then Campylobacter spp was detectedby Multiplex PCR using species specific genes.Result: The prevalence of Campylobacter spp. was 17% by conventional methods and 15% by molecularmethod. The results of antibiotic susceptibility test showed that, there is complete resistance (100%)to cephalothin, ampicillin, and clindamycin for both species, full resistance (100%) to trimethoprimsulfamethoxazol and erythromycin by C.coli, and high resistance (92.3%) to trimethoprim-sulfamethoxazoland erythromycin by C.jejuni, while the lowest resistance was to nalidixic acid and amikacin (7.7%) byC.jejuni, and (12.5%) to tetracyclin, amoxicillin, amikacin, chloramphenicol, and ciprofloxacin by C.coli.The frequency of biofilm production in all positive Skirrow’s culture was (35.29%) as 12 out of 34 positiveisolates, ranging from mild to severe biofilm formation. By PCR assay, 64.7 % (22 of 34) positive Skirrow’sculture were also positive based on hipO gene specific for C.jejuni, while the prevalence of asp gene was(23.5%).Conclusion: The prevalence of Campylobacter spp. was 17% by conventional methods and 15% by molecularmethods, most of Campylobacter jejuni and Campylobacter coli isolates were MDR, and sensitive only tolimited number of antibiotics, many Campylobacter isolates produce biofilm, there was highly significantcorrelation between hippurate hydrolysis results and molecular detection of Campylobacter spp. dependingon hipO and asp genes.

Infectious Diseases Society of America Guidance on the Treatment of Extended-Spectrum β-lactamase Producing Enterobacterales (ESBL-E), Carbapenem-Resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with Difficult-to-Treat Resistance (DTR-P. aeruginosa).

Antimicrobial-resistant infections are commonly encountered in US hospitals and result in significant morbidity and mortality. This guidance document provides recommendations for the treatment of infections caused by extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with difficult-to-treat resistance (DTR-P. aeruginosa). A panel of 6 infectious diseases specialists with expertise in managing antimicrobial-resistant infections formulated common questions regarding the treatment of ESBL-E, CRE, and DTR-P. aeruginosa infections. Based on review of the published literature and clinical experience, the panel provide recommendations and associated rationale for each recommendation. Because of significant differences in the molecular epidemiology of resistance and the availability of specific anti-infective agents globally, this document focuses on treatment of antimicrobial-resistant infections in the United States. Approaches to empiric treatment selection, duration of therapy, and other management considerations are briefly discussed. The majority of guidance focuses on preferred and alternative treatment recommendations for antimicrobial-resistant infections, assuming that the causative organism has been identified and antibiotic susceptibility testing results are known. Treatment recommendations apply to both adults and children. The field of antimicrobial resistance is dynamic and rapidly evolving, and the treatment of antimicrobial-resistant infections will continue to challenge clinicians. This guidance document is current as of 17 September 2020. Updates to this guidance document will occur periodically as new data emerge. Furthermore, the panel will expand recommendations to include other problematic gram-negative pathogens in future versions. The most current version of the guidance including the date of publication can be found at www.idsociety.org/practice-guideline/amr-guidance/.

Antibiotic susceptibility reporting and association with antibiotic prescribing: a cohort study

ObjectiveSelective reporting of antibiotic susceptibility test results may help guide appropriate antibiotic prescribing, particularly for urinary tract infections. Our objective was to describe laboratory urine culture susceptibility reporting practices and to estimate their impact on antibiotic prescribing in outpatients. MethodsWe examined all positive urine cultures with Escherichia coli, Klebsiella pneumoniae, or Proteus mirabilis associated with an antibiotic prescription among outpatients over 65 years of age in Ontario, Canada from 2014 through 2017. We evaluated antibiotic prescribing in the empirical window (1–3 days before culture result) and in the directed window (0–5 days after culture result). Unadjusted and adjusted odds ratios were reported to estimate the association between reporting and prescribing. ResultsIn total 113 780 eligible urine cultures from 48 laboratories were included in the study cohort. Susceptibility reporting practices were highly variable between laboratories, with a range across antibiotics from norfloxacin (n = 5/48, 10.4% reporting) to nitrofurantoin (n = 40/48, 83.3% reporting). Reporting antibiotic susceptibility was associated with increased odds of prescribing that antibiotic in the directed window (aOR 2.98, 95%CI 2.07–4.28). At the laboratory level, the proportion of urine cultures reporting specific antibiotic susceptibility results was also associated with an increase in prescribing of that antibiotic in the empirical window (adjusted OR 1.23, 95%CI 1.13–1.33, per 25% increase in reporting). ConclusionsLaboratory reporting of antibiotic susceptibility results for urine cultures is associated with empirical and directed prescribing of the reported antibiotics. Laboratories can play an important role in guiding appropriate antibiotic selection for urinary indications.

Low-cost multichannel system with disposable pH sensors for monitoring bacteria metabolism and the response to antibiotics

Antibiotic resistant bacteria are an important threat to human and animal health. Accurate antibiotic susceptibility test results are essential in medical control. We present a low-cost, simple, and rapid multichannel system for the registration of bacteria pH changes in time and the phenomena used to follow the microbial metabolic activity to evaluate the response to antibiotics. Small size silicon chips covered with a thin layer of Ta2O5 were employed as all-solid-state pH-sensors. The pH measurements were performed in 1 mL samples in Eppendorf tubes in which a liquid junction was formed by a rapidly wettable polymer pin. The tubes were fixed in a thermostatic bath filled with KCl with incorporated standard Ag/AgCl reference electrode. This system design permits the prevention of the reference electrode contact with the bacteria containing solution and eliminates the need for its cleaning and sterilization. The presented system was successfully applied for monitoring the response of Escherichia coli (E. coli), used as a model bacterium, to ampicillin, tetracycline, and kanamycin antibiotics in undiluted culture medium in just 5 hr. The proposed sensor fabrication cost is very low which permits disposable use.

Influence of Antibiotic Susceptibility Testing on Antibiotic Choice in Hospital-Acquired and Ventilator-Associated Pneumonia

Background: The survival of patients with hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) is largely determined by the timely administration of effective antibiotic therapy. Guidelines for the treatment HAP and VAP recommend empiric treatment with broad-spectrum antibiotics and tailoring of antibiotic therapy once results of microbiological testing are available. Objective: We examined the influence of bacterial identification and antibiotic susceptibility testing on antibiotic therapy for patients with HAP or VAP. Methods: We used the US Veterans’ Health Administration (VHA) database to identify a retrospective cohort of patients diagnosed with HAP or VAP between fiscal year 2015 and 2018. We further analyzed patients who were started on empiric antibiotic therapy, for whom microbiological test results from a respiratory sample were available within 7 days and who were alive within 48 hours of sample collection. We used the antibiotic spectrum index (ASI) to compare antibiotics prescribed the day before and the day after availability of bacterial identification and antibiotic susceptibility testing results. Results: We identified 4,669 cases of HAP and VAP in 4,555 VHA patients. The median time from respiratory sample receipt in the laboratory to final result of bacterial identification and antibiotic susceptibility testing was 2.22 days (IQR, 1.31–3.38 days). The most common pathogen was Staphylococcus aureus (n = 994), with methicillin resistance in 58% of those isolates tested. The next most common pathogen was Pseudomonas spp (n = 946 isolates). The susceptibility of antipseudomonal antibiotics, when tested, was as follows: 64% to carbapenems, 74% to cephalosporins, 75% to β-lactam/β-lactamase inhibitors, 69% to fluoroquinolones, and 95% to amikacin. Lactose-fermenting gram-negative bacteria (296 Escherichia coli and 360 Klebsiella pneumoniae) were also common. Among the 3,094 cases who received empiric antibiotic therapy, 607 (20%) had antibiotics stopped the day after antibiotic susceptibility results became available, 920 (30%) had a decrease in ASI, 1,075 (35%) had no change in ASI, and 492 (16%) had an increase in ASI (Fig. 1). Among the 1,098 patients who were not started on empiric antibiotic therapy, only 154 (14%) were started on antibiotic therapy the day after antibiotic susceptibility results became available. Conclusions: Changes in antibiotic therapy occurred in at least two-thirds of cases the day after bacterial identification and antibiotic susceptibility results became available. These results highlight how respiratory cultures can inform the treatment and improve antibiotic stewardship for patients with HAP/VAP.Funding: This study was supported by Accelerate Diagnostics.Disclosures: None

Surgery combined with antibiotics for the treatment of endogenous endophthalmitis caused by liver abscess

BackgroundsEndogenous endophthalmitis is a serious disease caused by intraocular infection that can rapidly progress to cause blindness. This study evaluated the clinical features, surgical and antibiotics treatment strategies, and treatment outcomes in patients with endophthalmitis caused by liver abscess.MethodsBetween April 2014 and April 2019, the clinical data of 16 patients (19 eyes) with endophthalmitis associated with liver abscess who underwent surgery at Shengjing Hospital were retrospectively analyzed. Furthermore, we evaluated the final visual outcomes in the patients to determine the efficacy of surgery.ResultsFifteen patients (18 eyes) underwent intravitreal injection followed by vitrectomy after admission. One patient (1 eye) only underwent intravitreal injection. Of the 16 patients, 3 patients (3 eyes) had recurrent intraocular inflammation and eventually underwent evisceration. Systemic antibiotics were administered for all patients based on the results of vitreous humor culture, blood culture, and antibiotic susceptibility tests. Outpatient follow-ups were performed until the patients were stable (6 months). Of the 19 eyes, 1 eye (5%) had visual acuity restored to 20/200, 6 eyes (31%) had visual acuity restored to counting fingers (CF), 2 eyes (11%) had visual acuity restored to hand motion (HM), 4 eyes (22%) showed only light perception (LP), and the remaining 6 eyes (31%) showed no light perception (NLP). Drug susceptibility tests suggested that the carbapenems exhibited significant effects in the inflammatory reaction.ConclusionEndogenous endophthalmitis caused by liver abscess is a very serious condition, and the final visual outcome is poor. Timely surgical intervention combined with antibiotic treatment is essential, and the primary disease must be treated to control disease progression at the earliest.

Risk factors for recurrence of Helicobacter pylori infection after successful eradication in Chinese children: A prospective, nested case‐control study

Limited research has been published on the recurrence of Helicobacter pylori infection and risk factors in Chinese children. Our study aimed to identify risk factors for Helicobacter pylori infection recurrence after successful eradication in children. A prospective, nested case-control study was performed. A cohort of 230 children with successful eradicationofHelicobacter pylori in Baoding (China) was selected from January 2018 to February 2019. A standardized questionnaire was used to obtain socioeconomic details. Eradication regimens and Helicobacter pylori antibiotic susceptibility testing results were also recorded. Interleukin-1β level, interferon-γ level, and genetic susceptibility (IFNGR1 and PTPRZ1 gene polymorphisms) were analyzed. All children were followed for 1year. Among 218 (94.8%) children who were successfully followed, 41 children (18.8%) had a Helicobacter pylori infection recurrence. The recurrence rate was higher in children ≤10years old than >10years old (22.8% vs 7.1%, P=.01). There was no significant difference between the recurrence group and the non-recurrence group in terms of types of therapy and antibiotic sensitivity (P>.05). Multivariable regression results indicated that residence in urban areas, higher household income, and having lunch at home were significantly protective against recurrence (OR 0.155, 0.408, and 0.351 respectively), whereas Helicobacter pylori infection in family members increased the risk of recurrence (OR 2.283). The levels of IL-1β and IFN-γ exhibited no significant difference between the recurrence group and the non-recurrence group. The allele frequency of G in the IFNGR1-56 site, A in the IFNGR1-600 site, and T in the IFNGR1-565 site was significantly higher in the recurrence group when compared to the non-recurrence group (P<.05). The Helicobacter pylori infection recurrence rate is high in children in Baoding region and is closely correlated to socioeconomic factors. The IFNGR1 gene polymorphism may be an independent risk factor for Helicobacter pylori infection recurrence.

Analytical Performance Validation of Next-Generation Sequencing Based Clinical Microbiology Assays Using a K-mer Analysis Workflow.

Next-generation sequencing (NGS) enables clinical microbiology assays such as molecular typing of bacterial isolates which is now routinely applied for infection control and epidemiology. Additionally, feasibility for NGS-based identification of antimicrobial resistance (AMR) markers as well as genetic prediction of antibiotic susceptibility testing results has been demonstrated. Various bioinformatics approaches enabling NGS-based clinical microbiology assays exist, but standardized, computationally efficient and scalable sample-to-results workflows including validated quality control parameters are still lacking. Bioinformatics analysis workflows based on k-mers have been shown to allow for fast and efficient analysis of large genomics data sets as obtained from microbial sequencing applications. We here demonstrate applicability of k-mer based clinical microbiology assays for whole-genome sequencing (WGS) including variant calling, taxonomic identification, bacterial typing as well as AMR marker detection. The wet-lab and dry-lab workflows were developed and validated in line with Clinical Laboratory Improvement Act (CLIA) guidelines for laboratory-developed tests (LDTs) on multi-drug resistant ESKAPE pathogens. The developed k-mer based workflow demonstrated ≥99.39% repeatability, ≥99.09% reproducibility and ≥99.76% accuracy for variant calling and applied assays as determined by intra-day and inter-day triplicate measurements. The limit of detection (LOD) across assays was found to be at 20× sequencing depth and 15× for AMR marker detection. Thorough benchmarking of the k-mer based workflow revealed analytical performance criteria are comparable to state-of-the-art alignment based workflows across clinical microbiology assays. Diagnostic sensitivity and specificity for multilocus sequence typing (MLST) and phylogenetic analysis were 100% for both approaches. For AMR marker detection, sensitivity and specificity were 95.29 and 99.78% for the k-mer based workflow as compared to 95.17 and 99.77% for the alignment-based approach. Summarizing, results illustrate that k-mer based analysis workflows enable a broad range of clinical microbiology assays, potentially not only for WGS-based typing and AMR gene detection but also genetic prediction of antibiotic susceptibility testing results.