Susceptibility Testing Of Isolates Research Articles

Agreement of antimicrobial susceptibility testing of Pasteurella multocida and Mannheimia haemolytica isolates from preweaned dairy calves with bovine respiratory disease.

Evaluate agreement among the antimicrobial susceptibility profiles of Mannheimia haemolytica or Pasteurella multocida obtained by transtracheal wash, nasal swab, nasopharyngeal swab, and bronchoalveolar lavage. 100 Holstein and Holstein-cross bull calves with bovine respiratory disease. Calves > 30 days old with naturally occurring bovine respiratory disease were sampled sequentially by nasal swab, nasopharyngeal swab, transtracheal wash, and then bronchoalveolar lavage. Samples were cultured, and for each antimicrobial, the MIC of 50% and 90% of isolates was calculated, and isolates were categorized as susceptible or not. Categorical discrepancies were recorded. Percent positive agreement and kappa values were calculated between isolates for each of the sampling methods. Antimicrobial susceptibility varied by pathogen and resistance to enrofloxacin, florfenicol, tilmicosin, and spectinomycin was detected. Minor discrepancies were seen in up to 29% of classifications, with enrofloxacin, penicillin, and florfenicol more frequently represented than other drugs. Very major and major discrepancies were seen when comparing florfenicol (1.9%) and tulathromycin (3.8 to 4.9%) across sampling methods. Some variability was seen in agreement for enrofloxacin for several comparisons (8.3 to 18.4%). Susceptibility testing of isolates from 1 location of the respiratory tract can reliably represent susceptibility in other locations. Nevertheless, the potential for imperfect agreement between sampling methods does exist. The level of restraint available, the skill level of the person performing the sampling, the age and size of the animal, disease status, and treatment history all must be factored into which test is most appropriate for a given situation.

Antimicrobial Resistance of <i>Pseudomonas aeruginosa</i> Isolated from Human Infections in N’Djamena, Chad

Background: Urinary Tract infections and pus are major public health problems. The evolution of bacterial resistance to antibiotics makes the treatment of these infections problematic. This is why this study is undertaken to identify and evaluate the resistance of Pseudomonas aeruginosa to antibiotics. Methods: This is a prospective study carried out from December 2020 to November 2021. The germs were isolated on the agar supplemented with cetrimide and identified by the API 20 NE gallery method according to the manufacturer’s protocol. The strains’ resistance profiles were determined by the diffusion method on Mueller-Hinton according to the criteria EUCAST- 2021. Results: A total of 46/1467 (3.13%) Pseudomonas aeruginosa were identified, of which 29/1008 (2.87%) were urinary tract infections and 17/459 (3.70%) were pus. The high resistances were: 97.8% to ceftazidim, 91.3% to aztreonam, 93.5% to cefepim, 82.6% to piperacillin, 58.7% to levofloxacin, 52.2% to amikacin, 47.8% to tazobactam-piperacillin, 47.8% to tobramycin and 43.5% to ciprofloxacin. Low resistance was only 2.2% to fosfomycin, 2.2% to colistin and 15.2% to imipenem. Conclusion: This study reveals the considerable resistance of Pseudomonas aeruginosa to commonly used antibiotics, and thus compromises the empirical treatment practiced in hospitals. This result motivates the need to carry out susceptibility testing of isolates before any prescription of antimicrobials.

Gut microbiota and age shape susceptibility to clostridial enteritis in lorikeets under human care

BackgroundEnteritis is a common cause of morbidity and mortality in lorikeets that can be challenging to diagnose and treat. In this study, we examine gut microbiota in two lorikeet flocks with enteritis (Columbus Zoo and Aquarium—CZA; Denver Zoo—DZ). Since 2012, the CZA flock has experienced repeated outbreaks of enteritis despite extensive diet, husbandry, and clinical modifications. In 2018, both CZA and DZ observed a spike in enteritis. Recent research has revealed that the gut microbiota can influence susceptibility to enteropathogens. We hypothesized that a dysbiosis, or alteration in the gut microbial community, was making some lorikeets more susceptible to enteritis, and our goal was to characterize this dysbiosis and determine the features that predicted susceptibility.ResultsWe employed 16S rRNA sequencing to characterize the cloacal microbiota in lorikeets (CZA n = 67, DZ n = 24) over time. We compared the microbiota of healthy lorikeets, to lorikeets with enteritis, and lorikeets susceptible to enteritis, with “susceptible” being defined as healthy birds that subsequently developed enteritis. Based on sequencing data, culture, and toxin gene detection in intestinal contents, we identified Clostridium perfringens type A (CZA and DZ) and C. colinum (CZA only) at increased relative abundances in birds with enteritis. Histopathology and immunohistochemistry further identified the presence of gram-positive bacilli and C. perfringens, respectively, in the necrotizing intestinal lesions. Finally, using Random Forests and LASSO models, we identified several features (young age and the presence of Rhodococcus fascians and Pseudomonas umsongensis) associated with susceptibility to clostridial enteritis.ConclusionsWe identified C. perfringens type A and C. colinum associated with lorikeet necrohemorrhagic enteritis at CZA and DZ. Susceptibility testing of isolates lead to an updated clinical treatment plan which ultimately resolved the outbreaks at both institutions. This work provides a foundation for understanding gut microbiota features that are permissive to clostridial colonization and host factors (e.g. age, prior infection) that shape responses to infection.

Bovine mastitis caused by rapid-growth environmental mycobacteria

Rapid-growth mycobacteria were isolated from two cases of cow mastitis with similar clinical appearance and within a narrow time frame. Mycobacteria were isolated on blood esculine agar. The isolated mycobacteria were Gram stained, Ziehl-Nielsen stained and tested for growth at 25°C, 37°C and 42°C, iron uptake, growth on Löwenstein-Jensen (LJ) agar with and without 5% NaCl, arylsulphatase (3 days), tween 80 hydrolysis, tellurite reduction, nitrate reductase and niacin synthesis. Molecular identification was performed using the Mycobacteria GenoType CM and AS tests (Hain Diagnostika, Nehren, Germany). One isolate was additionally sequenced for the hsp65, rpoB, 16S rRNA gene sequence and transcribed spacer sequence (ITS) DNA. Susceptibility testing of isolates was performed on the Sensititre Rapmycol plate (TREK Diagnostic Systems Ltd.) for trimethoprim/sulfamethoxasole, linezolid, ciprofloxacin, imipenem, moxifloxacin, cefepime, cefoxitin, amoxicillin / clavulanic acid, amikacin, ceftriaxone, doxycycline, minocycline, tigecycline, tobramycine and clarythromycine. Gram-positive acid-resistant rods were observed in stained smears. Both strains grew at 25°C, 37°C and 42°C on LJ medium, and on LJ medium containing 5 % NaCl. The conventional biochemical tests for iron uptake, arylsulphatase (3 days), Tween 80 hydrolysis, tellurite reduction and nitrate reductase were positive, while the niacin test was negative. Both isolates were identified by the GenoType Mycobacterium CM as Mycobacterium fortuitum II/ Mycobacterium mageritense, while application of the GenoType Mycobacterium AS kit identified both isolates as belonging to the species Mycobacterium smegmatis. Analysis of the isolate sequences (strain DS) for 16S ribosomal RNA confirmed a 100% identical result with Mycobacterium smegmatis strain INHR2. According to the CLSI criteria, both strains were sensitive to sulfametoxazole/trimethoprim, linezolid, doxicycline, amikacin and tobramycin. The strains differed in their sensitivity to cefoxitim, and both strains were resistant to clarithromycin. There was a strong difference between the isolates in sensitivity toward cefoxitime and tigecycline.

Frequency of Extensively Drug-Resistant Gram-Negative Pathogens in a Tertiary Care Hospital in Pakistan.

BackgroundGram-negative bacteria are frequently involved in nosocomial infections. These bacteria have a particular tendency to develop antibiotic resistance and may become extensively drug-resistant (XDR). This study aimed to detect the prevalence of XDR Gram-negative bacteria in a tertiary care hospital in Pakistan.Materials and methodsClinical samples were obtained from patients admitted to different inpatient wards and sent for microbial analysis and culture. Antibiotic susceptibility testing of isolates was performed by the disk diffusion method to detect XDR strains.ResultsAntibiotic susceptibility patterns of a total of 673 clinical samples were studied. Of all bacterial isolates, 64% were extensively drug-resistant. Klebsiella pneumoniae had the highest percentage of XDR isolates (68.4%), followed by Pseudomonas aeruginosa (67.6%) and Escherichia coli (56.1%). Most XDR pathogens were isolated from the burn unit (87.7%), followed by the intensive care unit (69.2%) and surgical unit (68.9%).ConclusionsThe rate of extensive drug-resistance is alarmingly high, which calls for strict surveillance and control measures to prevent the development of further resistance. Proper sanitation and rational prescription of antibiotics should be ensured.

Seven-Year Trend of Antimicrobial Resistance of Acinetobacter and Pseudomonas spp. Causing Bloodstream Infections: A Retrospective Study from Shiraz, Southern Iran

Background: Antimicrobial resistance is a growing healthcare system threat of huge concern worldwide. Objectives: This study aimed to report the seven-year trend of antimicrobial resistance of Acinetobacter and Pseudomonas spp. causing bloodstream infections (BSIs) in Shiraz, southern Iran, during 2010 - 2016. Methods: This retrospective study was conducted on the recorded blood cultures during 2010 - 2016. The susceptibility testing of isolates was performed by the agar diffusion test. Data were grouped into three episodes: 2010 to 2011, 2012 to 2013, and 2014 to 2016. The chi-square test was used to determine the significance of antimicrobial resistance trends. Results: The rates of resistance to antibiotics such as amikacin, cefepime, cefotaxime, ceftazidime, ciprofloxacin, and piperacillin-tazobactam were high within 2014 - 2016, with a statistically significant increasing trend over the abovementioned three periods. The resistance rates of Pseudomonas spp. to the antibiotics such as amikacin, tobramycin, gentamicin, cefepime, ceftazidime, and ciprofloxacin were high in 2014 - 2016 with a statistically significant increasing trend over the three periods. Conclusions: The increasing trend of antimicrobial resistance of Acinetobacter and Pseudomonas spp. to almost all the conventional antibiotics over the seven-year period of this study is alarming.

Antimicrobial susceptibility pattern of urinary isolates from outpatients suspected for urinary tract infection

Urinary tract infection (UTI) is one of the most common bacterial infections in humans and a major cause of morbidity. The pathogens traditionally associated with UTI and their antibiotic sensitivity patterns are changing from time to time and across different environment. Knowledge of the antibiotic resistance patterns of uropathogens in specific geographical locations is an important factor for choosing an appropriate empirical antimicrobial treatment. This study therefore evaluates the causative organisms present in urine specimen and their antibiotic susceptibility profile among patients suspected for UTI attending the general outpatient department clinic of the University of Port Harcourt Teaching Hospital, Nigeria. One hundred and fifty (150) mid-stream urine samples were collected from patients suspected of having a UTI and subjected to macroscopic assessment, isolation, and characterization as well as resistance- susceptibility test of isolates using standard conventional techniques. Results showed that UTI was frequently encountered in females 39 (26%) than males 21 (14%) while 60 % of the samples yielded no growth after 48 hours incubation. The most common pathogens isolated were Staphylococcus aureus (47.19%), followed by Escherichia coli (20.22%), Klebsiella pneumoniae (15.73%), Candida albicans (10.11%), Pseudomonas aeruginosa (5.62%) and Proteus mirabilis (1.12%). Staphylococcus aureus isolates were highly susceptible to Amoxicillin/Clavulanate (88.10%) with lower susceptibility to Ofloxacin (52%), Cloxacillin (50%). This information will directly affect selection of empirical therapy for UTI and emphasizes the need for choosing an appropriate antimicrobial treatment in specific geographical locations.

2386. Efficacy of Lefamulin (LEF) vs. Moxifloxacin (MOX) Against Common Pathogens in Adults With Community-Acquired Bacterial Pneumonia (CABP): Results From the Phase 3 Lefamulin Evaluation Against Pneumonia (LEAP 1) Study

BackgroundNew CABP treatments with targeted activity and improved tolerability are needed. LEF, a novel pleuromutilin antibiotic that binds to a conserved region of the bacterial ribosome, is in development for IV or oral CABP treatment. This Phase 3 clinical study evaluated the efficacy of LEF vs. MOX in adults with CABP.MethodsIn this multicenter, randomized, double-blind study, 551 adult patients with CABP (Patient Outcomes Research Team Risk Class ≥III) were randomized to LEF 150 mg IV Q12 hours (n = 276) or MOX 400 mg IV Q24 hours (n = 275). After 6 IV doses, qualifying patients could be switched to oral therapy. Adjunctive linezolid was given with MOX for suspected methicillin-resistant S. aureus.Primary outcomes were early clinical response (ECR) in the intent-to-treat (ITT) population (FDA endpoint), and investigator assessment of clinical response (IACR) at test of cure in the modified ITT (mITT) and clinically evaluable (CE-TOC) populations (co-primary EMA endpoints). The microITT population included all patients with a baseline CABP pathogen detected by respiratory tract or blood culture, urinary antigen test, serology, and real-time PCR from sputum, oropharyngeal and nasopharyngeal swabs. The microITT2 population included patients with a CABP pathogen detected by methods excluding PCR. Confirmatory identification and susceptibility testing of isolates, serology, and PCR were performed by a central laboratory.ResultsLEF was noninferior to MOX for ECR and IACR (LEF 87.3% [ITT], 81.7% [mITT], 86.9% [CE-TOC]; MOX 90.2% [ITT], 84.2% [mITT], 89.4% [CE-TOC]). The most common pathogen identified was S. pneumoniae. In the microITT population (n = 159 per arm), LEF and MOX demonstrated similar ECR and IACR rates (figure). LEF was efficacious against S. pneumoniae (including resistant phenotypes), H. influenzae, M. catarrhalis, S. aureus, and atypical pathogens. In the microITT2 population, response rates remained similar across baseline pathogens but showed more variation likely due to smaller sample sizes.ConclusionIn this first Phase 3 clinical trial, LEF showed similar efficacy to MOX against the most commonly identified CABP pathogens. LEF demonstrates promise as a targeted monotherapy for the treatment of CABP in adults. Disclosures T. File, BioMerieux: Scientific Advisor, Consulting fee. Curetis: Scientific Advisor, Consulting fee. Melinta: Scientific Advisor, Consulting fee. Merck: Scientific Advisor, Consulting fee. MotifBio: Scientific Advisor, Consulting fee. Nabriva: Investigator and Scientific Advisor, Consulting fee and Research grant. Pfizer: Scientific Advisor, Consulting fee. Paratek: Scientific Advisor, Consulting fee. L. Goldberg, Nabriva: Employee, Employee Stock Options and Salary. S. Paukner, Nabriva: Employee and Shareholder, Salary. A. Das, Achaogen: Consultant, Consulting fee. Cempra: Consultant, Consulting fee. Contrafect: Consultant, Consulting fee. Paratek: Consultant, Consulting fee. Tetraphase: Consultant, Consulting fee. Wockhardt: Consultant, Consulting fee. Theravance: Consultant, Consulting fee. Zavante: Consultant, Consulting fee. UTILITY: Consultant, Consulting fee. S. P. Gelone, Nabriva Therapeutics: Employee, Equity, Shareholder and Salary. Achaogen: Shareholder, Equity, Shareholder. J. Saviski, Nabrica Therapeutics, plc: Employee, Salary. C. Sweeney, Nabriva: Employee, employee stock options and Salary. E. Seltzer, Nabriva (previous employee and salary): Employee and Shareholder, Salary. G. H. Talbot, Nabriva Therapeutics: Board Member, Consultant and Shareholder, Consulting fee and stock options, board fees. L. B. Gasink, Nabriva: Employee, Salary.

Detection of alpha toxin and enterotoxins of Clostridium perfringens isolated from minced meat by real time polymerase chain reaction (PCR)

Clostridium perfringens is one of the most widespread pathogen producing toxins related to variable pathogenic conditions, particularly food poisoning in humans. Thus, this study described the prevalence, enumeration, toxigenic types and antibiotic susceptibility of C. perfringens strains isolated from minced meat in Egypt as well as the validation of a real-time polymerase chain reaction (PCR) test for the identification of C. perfringens toxin genes. A high prevalence of C. perfringens (98/105, 93.3%) was detected in minced meat samples. The total count of viable C. perfringens in 23 samples was 2.0 × 102 to 4.5 × 102 with a mean value 3.7 × 102 ± 1.07 × 102 CFU/g. The toxin typing of C. perfringens based on lecithinase activity and dermonecrotic reactions in albino guinea pig exhibited 33 (33.7%) as toxigenic strains of C. perfringens type A and 65 (66.3%) as non-toxigenic strains. Antibiotic susceptibility testing of isolates against 15 different antimicrobial agents indicated that C. perfringens was extremely sensitive to penicillin, followed by erythromycin, tetracycline, doxycycline and amoxicillin. All the other drugs were relatively less effective against the isolates. The real time PCR (RT-PCR) was performed for screening of alpha (cpa), beta, epsilon, iota toxins and enterotoxin (cpe) genes in toxigenic isolates of C. perfringens type A. All toxigenic strains of C. perfringens type A (33, 33.7%) were positive for alpha toxin (cpa) and enterotoxin (cpe) genes, while none of these isolates carried beta, epsilon and iota toxin genes. To the best of the authors’ knowledge, this is one of the studies that used RT-PCR for the determination of toxigenic strains of C. perfringens in Egypt. It is suggested that RT-PCR could be used instead of the conventional culture procedures for identification of C. perfringens in minced meat in Egypt. Key words: Clostridium perfringens, minced meat, alpha toxin (cpa) gene, enterotoxin (cpe) gene, real time-polymerase chain reaction (RT-PCR).

Bacteriological Screening of Paediatric Cough Syrups Marketed Within Port Harcourt Metropolis, South-South Nigeria

Non-adherence to good manufacturing practice alongside improper handling during dispensing, packaging and inadequate post-marketing surveillance of pharmaceutical products accounts to product’s deterioration reduced therapeutic effect and adversely affects patient’s safety especially the paediatrics. This study evaluates the microbiological quality of various brands of paediatric cough syrups marketed and used within Port Harcourt metropolis. Twenty cough syrup brands were experimented on in duplicate, coded as USS and UNS (used and unused respectively). They were subjected to organoleptic assessment, pH, viscosity, total aerobic viable count, as well as resistance- susceptibility test of isolates using standard conventional techniques. Results showed viscosity value of 0.22 - 9.09 Pascal seconds (Pa.s), pH values of 3.13 - 8.34 across the UNS and USS categories respectively. While 80% of the UNS cough syrup samples were free from potential microbial threat, 20% fraction and all USS cough syrup (100%) samples were contaminated with objectionable microorganisms and non- compliant with USP permissible limit. The potentially pathogenic isolates were Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumonia, demonstrating varied resistance pattern to exposed antibiotic categories. Microbial contamination might have been caused by poor quality control and improper handling of the products during use. This calls for more stringent measures during product manufacturing and handling to ensure patient’s safety and forestall possible transference of resistance strain.

Prevalence of Extended Spectrum Beta Lactamase Producing Escherichia coli and Pseudomonas aeruginosa Isolated from Clinical Samples

There has been an increasing attention globally over the rising treatment failures caused by Extended Spectrum Beta-Lactamase (ESBL) producing organisms when new generation antibiotics are used. This study was carried out to investigate the prevalence of ESBL producing Escherichia coli and Pseudomonas aeruginosa isolates from the Federal Medical Centre (FMC) Owerri, Imo State, Nigeria. Two hundred and fifty clinical isolates comprising, E. coli (136) and P. aeruginosa (114) was used for the study. Antimicrobial susceptibility testing of isolates was determined using the disc diffusion method. ESBL phenotypes were further determined by the double disc synergy test using Ceftazidime, Cefotaxime, Ceftriazone and Amoxicillin clavulanic acid. Out of the 250 isolates tested, 114 (45.6%) were positive for ESBL production comprising 66(26.4%) E. coli and 48(19.2%) P. aeruginosa. The antimicrobial sensitivity testing showed that the highest resistance of 100% was recorded with Cephalexine while the least of 0% was recorded with the aminoglycosides and quinolones, giving a clear indication that the aminoglycosides and quinolnes could be recommended for the treatment of ESBL infections caused by these organisms. The result of the present study showed that there is apparently high prevalence of ESBL producing E. coli and P. aeruginosa in the Federal Medical Centre (FMC) Owerri, Imo State, Nigeria.

Randomized clinical trial to evaluate the effect of fecal microbiota transplant for initial Clostridium difficile infection in intestinal microbiome.

ObjectiveThe aim of this study was to evaluate the impact of fecal donor-unrelated donor mix (FMT-FURM) transplantation as first-line therapy for C. difficile infection (CDI) in intestinal microbiome.MethodsWe designed an open, two-arm pilot study with oral vancomycin (250mg every 6 h for 10–14 days) or FMT-FURM as treatments for the first CDI episode in hospitalized adult patients in Hospital Universitario “Dr. Jose Eleuterio Gonzalez”. Patients were randomized by a closed envelope method in a 1: 1 ratio to either oral vancomycin or FMT-FURM. CDI resolution was considered when there was a reduction on the Bristol scale of at least 2 points, a reduction of at least 50% in the number of bowel movements, absence of fever, and resolution of abdominal pain (at least two criteria).From each patient, a fecal sample was obtained at days 0, 3, and 7 after treatment. Specimens were cultured to isolate C. difficile, and isolates were characterized by PCR. Susceptibility testing of isolates was performed using the agar dilution method. Fecal samples and FMT-FURM were analyzed by 16S rRNA sequencing.ResultsWe included 19 patients; 10 in the vancomycin arm and 9 in the FMT-FURM arm. However, one of the patients in the vancomycin arm and two patients in the FMT-FURM arm were eliminated. Symptoms resolved in 8/9 patients (88.9%) in the vancomycin group, while symptoms resolved in 4/7 patients (57.1%) after the first FMT-FURM dose (P = 0.26) and in 5/7 patients (71.4%) after the second dose (P = 0.55). During the study, no adverse effects attributable to FMT-FURM were observed in patients.Twelve isolates were recovered, most isolates carried tcdB, tcdA, cdtA, and cdtB, with an 18-bp deletion in tcdC. All isolates were resistant to ciprofloxacin and moxifloxacin but susceptible to metronidazole, linezolid, fidaxomicin, and tetracycline. In the FMT-FURM group, the bacterial composition was dominated by Firmicutes, Bacteroidetes, and Proteobacteria at all-time points and the microbiota were remarkably stable over time. The vancomycin group showed a very different pattern of the microbial composition when comparing to the FMT-FURM group over time.ConclusionThe results of this preliminary study showed that FMT-FURM for initial CDI is associated with specific bacterial communities that do not resemble the donors’ sample.

English

Nosocomial infections due to multidrug resistant Staphylococcus aureus are an important health problem worldwide. Antimicrobial resistance prolongs the duration of hospitalization, thereby increasing the cost of patient care. For a long time, methicillin was considered as drug of choice for treatment of penicillin-resistant staphylococcal infections. Emergence of methicillin resistance reduced the available options for treatment of nosocomial and community acquired S. aureus. Normally, such strains are only sensitive to glycopeptides such as vancomycin and teicoplanin. Recent reports show that methicillin resistant S. aureus (MRSA) have become multiply resistant to other drugs such as fluoroquinolones, trimethoprim-sulfamethoxazole (SXT), clindamycin or erythromicin and there are reports of vancomycin resistant strains from different parts of the world. The aim of this study was to determine the susceptibility patterns of Staphylococcus isolates from humans. Drug susceptibility testing of isolates was determined using the disk diffusion method. A total of 110 S. aureus (SA) and 23 coagulase negative staphylococcus (CoNS) isolates from human sources were studied. Both SA and CoNS isolates were completely sensitive to vancomycin. On one hand, there was a comparable high resistance for both SA and CoNS to penicillin G, augmentin and tetracycline. On the other hand, there was significantly high resistance to erythromycin (69.6%), SXT (69.6%), oxacillin (82.6%), ciprofloxacin (52.2%) and clindamycin (39.1%) among CoNS when compared with SA isolates (erythromycin 38.2%, SXT 38.2, oxacillin (33.6%), ciprofloxacin (26.4%), clindamycin 18.2%) with p values 0.0090, 0.0099, 0.0001, 0.0239 and 0.0483, respectively. These high levels of resistance, calls for continuous surveillance studies to monitor for S. aureus infections in the community and hospital settings and the emergence of vancomycin resistant isolates. Key words: Methicillin resistant, Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA), antibiotic susceptibility, vancomycin, coagulase negative staphylococci.

Identification of Pathogenic Bacteria in Blood Cultures and Susceptibility Testing of Isolates With Various Antibiotics

Background: Blood infections are an extensive range of disorders that can vary from limited bacteremia to fatal septicemia. Bac- teremia refers to the transient presence of a bacterium in the bloodstream. A delay in the diagnosis and treatment of sepsis can cause mortality, with a 20% - 50% prevalence rate. Objectives: Due to the changing patterns of antibiotic resistance, as well as dierences in patterns over time in dierent settings, we decided to identify infectious agents and their antibiotic resistance patterns in blood cultures. Materials and Methods: This study was conducted at Shahid Beheshti hospital, Hamadan, Iran, during a one-year period (March 21, 2014, to March 22, 2015). From patients with suspected bloodstream infections, 5-10 mL of blood was collected three times and inoculated into culture bottles. After identifying the types of microorganisms, susceptibility testing was performed according to CLSI standards, and the results were analyzed with statistical software. Results: In the present study, 2,130 blood cultures were obtained from 710 patients (384 females and 326 males). Of these cultures, 232 (18.9%) were positive; 107 (46%) and 125 (54%) were from females and males, respectively. Most of the positive cultures were re- lated to the internal medicine and hematology wards, which had 132 cases (56.9%), and the ICU, with 37 cases (16%). The most frequent isolates were Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and coagulase-negative Staphylococcus aureus, with prevalence rates of 18.2%, 24.1%, 10.3%, and 10.3%, respectively. The most eective antibiotic against Gram-positive isolates was van- comycin. Conclusions: This study revealed that the most eective antibiotics against two Gram-negative and Gram-positive groups were amikacin and norfloxacin, so it is recommended that these antibiotics be used empirically, at least in the setting where this study was conducted, before performing the culturing and antibiogram process.

Performance of extended spectrum beta lactamases (ESBL) screening agar in various clinical specimens

Performance of extended spectrum beta lactamases (ESBL) screening agar in various clinical specimens

95 Susceptibility testing of isolates of Pseudomonas aeruginosa in patients with cystic fibrosis – Service evaluation

95 Susceptibility testing of isolates of Pseudomonas aeruginosa in patients with cystic fibrosis – Service evaluation

In Vitro Evaluations of Topical Agents to Treat Acanthamoeba Keratitis

To evaluate the effectiveness of topical agents for the treatment of Acanthamoeba keratitis (AK). Laboratory research. Fifty-six Acanthamoeba isolates from 56 patients with clinically proven AK were studied. The effectiveness of 7 agents against Acanthamoeba cysts was determined in vitro. The agents were 1.0% povidone-iodine, 0.05% benzalkonium chloride (BZC), 0.02% chlorhexidine gluconate (CHG), 0.1% propamidine isethionate, 0.02% polyhexamethylene biguanide (PHMB), 5.0% natamycin, and 1.0% voriconazole (VRCZ). These concentrations are those recommended for patients. In addition, 10-fold dilutions of each of the agents were tested. After exposing the cysts to each agent at 35°C for 1 hour or 24 hours, the agents were removed by centrifugal washing. The exposed cysts were observed by optical microscopy for 7 days. In addition, the fine structures of the exposed isolates were examined by transmission electron microscopy (TEM). The genotype of the isolates was determined by 18S rDNA fragment sequencing. The in vitro susceptibility was determined by complete growth inhibition, and the morphologic appearance was determined by TEM. The genotypes of the 56 isolates were determined by 18S rDNA fragment sequencing. The Acanthamoeba cysts were most susceptible to natamycin, followed by povidone-iodine, BZC, PHMB, propamidine, and CHG. None of the strains was susceptible to VRCZ. The susceptibilities to PHMB and CHG may be time dependent and to propamidine may be concentration dependent. Transmission electron microscopy showed changes in the inner structure of the cysts exposed to natamycin and povidone-iodine. The Acanthamoeba genotype was T4 in 52 isolates, and cysts with the same genotype had different agent susceptibilities. Natamycin and povidone-iodine had excellent cysti-static (or cystcidal) effects, and PHMB and propamidine did not. There was no correlation between agent effectiveness and Acanthamoeba genotype. Therefore, susceptibility tests of isolates are needed to choose the most appropriate agent, and our results can be a guideline for choosing the most appropriate agent for immediate empirical treatment of AK.

Laboratory surveillance of invasive pneumococcal disease in New South Wales, Australia, before and after introduction of 7-valent conjugate vaccine: reduced disease, but not antibiotic resistance rates

We compared serotype distributions of Streptococcus pneumoniae isolates from patients aged <5 and o5 years with invasive pneumococcal disease in New South Wales, Australia, and antibiotic susceptibilities of isolates from the <5 years age group only, before (2002–2004) and after(2005–2009) introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). Overall, there were significant decreases in the mean annual number of referred isolates (770 vs. 515) and the proportion belonging to PCV7 serotypes (74% vs. 38%), but non-PCV7 serotypes, particularly 19A, increased (5% vs. 18%). All changes were more marked in the <5 years age group.Susceptibility testing of isolates from the <5 years age group showed variation in resistance between serotypes, but significant overall increases in penicillin non-susceptibility (23% vs. 31%),ceftriaxone resistance (2% vs. 12%) and multidrug resistance (4% vs. 7%) rates ; erythromycin resistance fell (32% vs. 25%). Continued surveillance is needed to monitor changes following the introduction of 13-valent PCV in 2012.

Direct inoculation method using BacT/ALERT 3D and BD Phoenix System allows rapid and accurate identification and susceptibility testing for both Gram-positive cocci and Gram-negative rods in aerobic blood cultures

This study describes a direct inoculation method using the automated BacT/ALERT 3D and the BD Phoenix System in combination for identification and susceptibility testing of isolates from positive blood cultures. Organism identification and susceptibility results were compared with the conventional method for 211 positive aerobic blood cultures. Of 110 Gram-positive cocci (GPCs), 98 (89.1%) isolates were correctly identified to the species level. Of 101 Gram-negative rods (GNRs), 98 (97.0%) isolates were correctly identified to the species level. The overall categorical agreement in antimicrobial susceptibility testing among the 110 GPCs was 92.7%, with 0.04% very major and 0.7% major error rates. The overall categorical agreement among 78 isolates of enterobacteria and 23 isolates of nonfermenters in GNRs was 99.5% and 91.1%, respectively, with no major errors identified. We conclude that, compared with previously reported direct inoculation methods, our method is superior in identification and susceptibility testing of GPCs.

Penicillin Susceptibility and Macrolide-Lincosamide-Streptogramin B Resistance in Group BStreptococcusIsolates from a Canadian Hospital

Intrapartum antibiotic prophylaxis (IAP) is recommended for pregnant women who test positive for group B Streptococcus (GBS) in their genitourinary tract to prevent GBS-induced neonatal sepsis. Penicillin G is used as the primary antibiotic, and clindamycin or erythromycin as the secondary, if allergies exist. Decreased susceptibility to penicillin G has occasionally been reported; however, clindamycin and erythromycin resistance is on the rise and is causing concern over the use of clindamycin and erythromycin IAP. Antibiotic resistance was characterized phenotypically using a D-Test for erythromycin and clindamycin, while an E-Test (E-strip) was used for penicillin G. GBS was isolated from vaginal-rectal swabs and serologically confirmed using Prolex (Pro-Lab Diagnostics, Canada) streptococcal grouping reagents. Susceptibility testing of isolates was performed according to the Clinical Laboratory Standards Institute guidelines. All 158 isolates were penicillin G sensitive. Inducible macrolide-lincosamide-streptogramin B (MLSB) resistance was observed in 13.9% of isolates. Constitutive MLSB resistance was observed in 12.7% of isolates. M phenotype resistance was observed in 6.3% of isolates. In total, erythromycin resistance was present in 32.9% of the GBS isolates, while clindamycin resistance was present in 26.6%. The sampled GBS population showed no sign of reduced penicillin susceptibility, with all being well under susceptible minimum inhibitory concentration values. These data are congruent with the large body of evidence showing that penicillin G remains the most reliable clinical antibiotic for IAP. Clindamycin and erythromycin resistance was higher than expected, contributing to a growing body of evidence that suggests the re-evaluation of clindamycin and erythromycin IAP is warranted.