Antimicrobial Susceptibility Of Bacteria Research Articles

Metabolic Modulation-Mediated Antibiotic and Immune Activation for Treatment of Chronic Lung Infections.

The Pseudomonas aeruginosa biofilm in recalcitrant chronic lung infections not only develops high antimicrobial tolerance but also induces an aberrant host inflammatory response. The metabolic condition plays a vital role in both the antimicrobial susceptibility of bacteria and the inflammatory response of immune cells, thereby offering a potential therapeutic target. Herein, we described a metabolic modulation strategy by using ultrasound-responsive liposomal nanoparticles containing a sonosensitizer and a hypoxia-activated prodrug against biofilm-associated chronic lung infections. Under ultrasound stimulation, the sonosensitizer generates antibacterial reactive oxygen species by oxygen consumption. Subsequently, the oxygen consumption-mediated hypoxia not only induces the anaerobic metabolism of bacteria for antibiotic activation but also triggers the glycolysis pathway of immune cells for inflammatory activation. Such metabolic modulation strategy demonstrated efficient therapeutic efficacy for P. aeruginosa biofilm-induced chronic lung infections in mice models and provides a promising way for combating biofilm-associated chronic infections.

Associations of antimicrobial use with antimicrobial susceptibility at the calf level in bacteria isolated from the respiratory and digestive tracts of veal calves before slaughter.

ObjectivesAntimicrobial drugs are frequently administered in veal calves, but investigations on associations with antimicrobial susceptibility of bacteria are scarce and convey partly contradictory findings. The aim of this study was to investigate associations of antimicrobial use (AMU) during the fattening period with antimicrobial susceptibility shortly before slaughter.MethodsDetailed treatment data of 1905 veal calves from 38 farms were collected prospectively during monthly farm visits for 1 year (n = 1864 treatments, n = 535 visits); 1582 Escherichia coli, 1059 Pasteurella multocida and 315 Mannheimia haemolytica were isolated from rectal and nasopharyngeal swabs collected before slaughter and subjected to antimicrobial susceptibility testing by microdilution. Associations of antimicrobial treatments with resistant isolates were investigated at the calf level.ResultsAssociations of AMU with antimicrobial resistance were observed using generalized linear models. For E. coli, the odds of being resistant were increased with increased AMU (OR 1.36 when number of treatments >1, P = 0.066). Use of tetracyclines was associated with resistance to tetracycline (OR 1.86, P < 0.001) and use of penicillins was associated with resistance to ampicillin (OR 1.66, P = 0.014). No significant associations were observed for P. multocida (use of aminoglycosides: OR 3.66 for resistance to spectinomycin, P = 0.074). For M. haemolytica, the odds of being resistant were increased with increased AMU (OR 4.63, P < 0.001), and use of tetracyclines was associated with resistance to tetracycline (OR 6.49, P < 0.001).ConclusionsOccurrence of resistant bacteria shortly before slaughter was associated with AMU in veal calves. Prudent and appropriate use may contribute to limit the selection of resistant bacteria on veal farms.

Appropriateness of Empirical Fluoroquinolones Therapy in Patients Infected with Escherichia coli, Klebsiella pneumoniae, or Pseudomonas aeruginosa: The Importance of the CLSI Breakpoints Revision.

PurposeEmpirical antibiotic therapy should follow the local bacterial susceptibility, and the breakpoints revisions of the antimicrobial susceptibility testing can reflect the changes in the antimicrobial susceptibility of bacteria. This study aimed to analyze whether the changes in the antimicrobial susceptibility to antibiotics caused by the breakpoint revision will affect the empirical antibiotic therapy and its appropriateness.Patients and MethodsA retrospective study was conducted among 831 hospitalized patients infected by Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa from April 10, 2018, to April 11, 2020. We evaluated the appropriateness of empirical therapy based on the antimicrobial susceptibility testing results. The rate of empirical use and appropriateness of fluoroquinolones was calculated, and logistic regression was used to analyze influencing factors of empirical use of fluoroquinolones.ResultsThe susceptibility rate of the three bacteria to levofloxacin (50.78% vs 32.06%) and ciprofloxacin (48.45% vs 21.90%) was decreased (P<0.001), while the resistance rate to levofloxacin (45.74% vs 58.73%) and ciprofloxacin (46.90% vs 66.67%) was increased (P<0.001) after the breakpoints revision. The empirical usage rate of fluoroquinolones in patients infected with Escherichia coli, Klebsiella pneumoniae, or Pseudomonas aeruginosa was 20.94%, which was influenced by the breakpoint revision (P=0.022), age (P=0.007), and the department (P=0.006); the appropriateness rate was 28.74%, affected by the pathogenic bacteria (P=0.001) and multidrug-resistant microorganism (P=0.001), department (P=0.024), and the length of stay before the empirical therapy (P=0.016).ConclusionThe susceptibility of bacteria to antibiotics has changed significantly after the breakpoint revision while the clinicians’ empirical therapy failure to change accordingly, which results in the decrease of the appropriateness of empirical use. It is enlightened that we should conduct more research to evaluate the rational use of antibiotics from the laboratory perspective and carry out interventions such as education and supervision to strengthen the collaboration between the microbiology laboratories and clinicians to improve the empirical antibiotic therapy and slow down the antimicrobial resistance.

Frequency of occurrence and antimicrobial susceptibility of bacteria isolated from respiratory samples of patients hospitalized with pneumonia in Western Europe, Eastern Europe and the USA: results from the SENTRY Antimicrobial Surveillance Program (2016-19).

BackgroundThe SENTRY Antimicrobial Surveillance Program monitors the frequency of occurrence and antimicrobial susceptibility of organisms from various infection types worldwide.ObjectivesTo evaluate the SENTRY programme results for organisms isolated from respiratory samples of patients hospitalized with probable pneumonia.MethodsA total of 28 918 bacterial isolates were consecutively collected (one per patient) in 2016–19 from 121 medical centres located in western Europe (W-EU; n = 7966), eastern Europe (E-EU; n = 3182) and the USA (n = 17 770) and then susceptibility tested by reference broth microdilution methods in a central laboratory.ResultsGram-negative bacilli (GNB) represented 76.3%, 88.6% and 69.1% of organisms; non-fermentative (NF) GNB accounted for 26.9%, 51.8% and 34.6% of organisms in W-EU, E-EU and USA, respectively. Pseudomonas aeruginosa susceptibility to piperacillin/tazobactam and meropenem was 75.4% and 76.9% in W-EU, 57.4% and 48.3% in E-EU, and 76.1% and 74.8% in the USA, respectively. Only 10.4% of Acinetobacter baumannii isolates from E-EU were meropenem susceptible compared with 45.8% in W-EU and 58.8% in the USA. Overall MRSA rates were 21.4% in W-EU and 28.7% in E-EU. In the USA, MRSA rates decreased from 44.8% in 2016 to 40.1% in 2019. Carbapenem resistance among Enterobacterales decreased continuously in the USA from 3.0% in 2016 to 1.7% in 2019 (2.4% overall) and was higher in E-EU (16.6%) than W-EU (2.2%). Klebsiella pneumoniae susceptibility to meropenem was 91.3%, 72.5% and 95.3% in W-EU, E-EU and the USA, respectively.ConclusionsRank order and antimicrobial susceptibility of bacteria isolated from patients with pneumonia widely varied by geography. MDR NF-GNB represented an important cause of pneumonia.

Rapid antimicrobial susceptibility testing from positive blood cultures based on Stimulated Raman Scattering Imaging analysis

The existing identification (ID) and antimicrobial susceptibility testing (AST) method requires at least two to three days to detect blood infection, and a fast and accurate detection method is very necessary for sepsis patients or Intensive Care Unit (ICU) patients. Here, we describe a direct isolated bacteria from a positive blood culture bottle (PBCB), and rapid AST method by femtosecond stimulated Raman scattering (SRS) imaging of deuterium oxide (D2O) metabolism, which can determine the antimicrobial susceptibility of bacteria from PBCB in 5-6 hours. The positive blood culture sample is passed through a filter membrane and mixed with cell lysis, after through the centrifugal which can directly isolated bacterium in order to identification by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS), following by antibiotic susceptibility testing by SRS imaging within a day. Overall, this rapid and rapid process combination of MALDI-TOF MS and SRS imaging of deuterium oxide (D2O) metabolism can solve the direct identification and antibiotic susceptibility testing of pathogen in positive blood cultures.

Frequency and antimicrobial susceptibility of bacteria causing bloodstream infections in pediatric patients from United States (US) medical centers (2014–2018): therapeutic options for multidrug-resistant bacteria

Studies evaluating large series of pediatric patients with bloodstream infections (BSIs) are scarce. We evaluated the frequency and antimicrobial susceptibility of organisms isolated from pediatric patients with BSI and therapeutic options for BSI caused by multidrug-resistant (MDR) organisms. A total of 2423 organisms were consecutively collected from 33 US medical centers between 2014 and 2018, and susceptibility was tested by reference broth microdilution methods. Isolates with an extended-spectrum β-lactamase phenotype were screened for β-lactamase genes. Overall, 40.2% of organisms were Gram-negative bacteria, 57.0% Gram-positives, and 2.8% Candida spp. The 5 most common organisms were Staphylococcus aureus (26.0%), Escherichia coli (13.0%), coagulase-negative staphylococci (8.3%), Enterococcus faecalis (7.1%), and Klebsiella pneumoniae (6.9%). Among S. aureus, 26.0% were oxacillin-resistant and 99.8% were susceptible to ceftaroline (MIC50/90, 0.25/0.5 mg/L). Enterobacterales and Pseudomonas aeruginosa isolates combined represented >85% of Gram-negative bacteria, and all isolates (100.0%) were susceptible to ceftazidime-avibactam.

Antimicrobial susceptibility of bacteria ısolated from blood cultures comparison of CLSI and EUCAST standards in the ınvestigation

Antimicrobial susceptibility of bacteria ısolated from blood cultures comparison of CLSI and EUCAST standards in the ınvestigation

Perfil de Sensibilidade aos Antibióticos na Infeção Urinária em Ambulatório no Distrito de Coimbra: Um Estudo Transversal

Urinary tract infections in the community setting are quite common. It is necessary to be aware of antibiotic susceptibility patterns in order to provide rational empirical therapy. The aim of this study is to determine the frequency and antimicrobial susceptibility of the strains responsible for urinary tract infections in primary health care, in the district of Coimbra, Portugal. In this observational and cross-sectional study, we analyzed 7134 positive urine cultures of outpatient laboratories in the district of Coimbra, over one year. In most cases, a positive culture was defined by a threshold of 105 colony-forming units per milliliter and was conducted by the automated system VITEK® 2, by bioMérieux. We used descriptive and inferential statistics to determine the prevalence and antimicrobial susceptibility of bacteria and to ascertain whether there were differences associated with sex and age. From the total of positive cultures, 83.4% pertained to females and 41.0% to individuals over 75 years old. Escherichia coli was the most frequent strain (63.9%), although its prevalence was lower (p < 0.001) in males and individuals over 75 years old. Its susceptibility to fosfomycin and nitrofurantoin was higher than 95% and with ciprofloxacin and trimethoprim/sulfamethoxazole it was lower than 80%. Resistances were more frequent (p < 0.001) in males and in the elderly. Escherichia coli was the most frequent strain, revealing less resistance to fosfomycin and nitrofurantoin. Antimicrobial susceptibility was lower in the elderly and in males, populations in whom empirical therapy may be less successful. In order to improve clinical results, we recommend periodic surveillance of antimicrobial susceptibility, which could enable the provision of efficient information to clinicians, namely those who prescribe empirically for such infections, as well as standardization of identification methods of bacterial strains diagnosis and of the antibiotic kits to be tested.

Antimicrobial susceptibility of bacteria from healthy cattle and sheep at slaughter.

Antimicrobial susceptibility of bacteria from healthy cattle and sheep at slaughter.

Prevalence of Bacterial and Fungal Isolates Associated with Road Traffic Accident In-patients in General Hospitals in Niger State

Aim: This study was carried out to determine the prevalence and antimicrobial susceptibility of bacteria and fungi isolated from wounds of in-patients with road traffic accidents at four General hospitals in Niger State.&#x0D; Place and Duration of Study: Department of Microbiology, Federal University of Technology, Minna, Nigeria, between October 2017 and May 2018.&#x0D; Methodology: Wound swabs were taken twice per patient, first swab at contact and second swab taken seven days post wound dressing. The outcome of 1000 wound swabs taken from 409 (267 male and 142 female) in-patients with road traffic accident wound treated in the General hospitals Bida, Minna, Kontagora and Suleja areas of Niger State, Nigeria.&#x0D; Results: The results showed that 405 (40.5%) samples were positive for bacteria and fungi pathogens while 595 (59.5%) were negative. 262 (80.6%) swabs yielded single isolates while 46 (14.2%) yielded double organisms and 17 (5.2%) yielded three or more organisms. Of the 405 positive cultures, 347 (85.7%) were bacterial isolates while 58 (14.3%) were fungal isolates. Staphylococcus aureus predominates (37.7%), followed by Pseudomonas aeruginosa (15.6%), E. coli (11.4%), Streptococcus pyogenes (9.4%), Bacillus subtillis (7.2%), Klebsiella pneumonia (4.4%), Aspergillus niger (4.2%), Candida albicans (3.7%), Aspergillus flavus (2.7%), Candida pseudotropicallis (2.2%) and Mucor pusillus (1.5%).&#x0D; Conclusion: Most bacterial isolates were sensitive to Levofloxacin, Ciprofloxacin, Streptomycin and Gentamycin, while others showed some degree of resistance to the remaining antibiotics. Klebsiella pneumoniae showed the highest resistance to all the antibiotics used. All the fungi isolated were highly sensitive to the antifungal drugs used except Griseofulvin.

Bacterial isolates, antimicrobial susceptibility and multidrug resistance in cultures from samples collected from beef and pre-production dairy cattle in New Zealand (2003–2016)

ABSTRACTAims: To describe the common species and the antimicrobial susceptibility of bacteria cultured from samples submitted to commercial veterinary diagnostic laboratories from beef and pre-production dairy cattle between 2003–2016, and to describe the proportion of isolates with multidrug resistance (MDR).Methods: Bacterial culture and antimicrobial susceptibility data from July 2003 to March 2016 were obtained from commercial veterinary diagnostic laboratories in New Zealand. Results were included from samples from beef cattle, irrespective of age or sex, dairy-breed females aged <2 years and dairy-breed males of any age. Submission information provided included the specimen description, the organisms cultured, and the antimicrobial susceptibilities of isolates, if tested. Antimicrobial resistance (AMR) was defined as any isolate not showing susceptibility to an antimicrobial compound and MDR as any isolate showing AMR to ≥3 antimicrobial classes.Results: There were 1,858 unique laboratory submissions, yielding 2,739 isolates. Of these submissions, most were from the Canterbury (389; 21.9%), Manawatu (388; 21.9%) Waikato (231; 12.4%) and Hawke’s Bay (136; 7.3%) regions. There were 163 unique species identifications for the 2,739 isolates; the most common were Yersinia pseudotuberculosis (452; 16.5%), Campylobacter jejuni (249; 9.1%), Escherichia coli (230; 8.4%) and Salmonella enterica serovar Typhimurium (143; 5.2%). Only 251/2,739 (9.2%) isolates from 122/1,858 (6.6%) submissions had antimicrobial susceptibility results. There were no sensitivity results for Yersinia spp., and only one each for Salmonella spp., and Campylobacter spp. Amongst the isolates tested, susceptibility to ampicillin was lowest (33/56; 58.9%). Overall, 57/251 (20.7%) isolates tested for antimicrobial susceptibility had MDR, and MDR was most common for Enterococcus spp. (12/17; 71%) and E. coli (13/30; 43%).Conclusions and Clinical Relevance: This is the first report on antimicrobial susceptibility and MDR in New Zealand beef and pre-production dairy cattle. Findings highlight the limited use of bacterial culture and sensitivity testing by veterinarians and deficits in the information accompanying submissions. A national antimicrobial resistance surveillance strategy that specifically includes this population is recommended.

1004. Frequency of Occurrence and Antimicrobial Susceptibility of Bacteria Isolated From Patients Hospitalized With Bloodstream Infections in United States Medical Centers (2015–2017)

BackgroundBloodstream infections (BSIs) cause significant morbidity and mortality. We evaluated the frequency and antimicrobial susceptibility of bacteria causing BSIs in the United States.MethodsA total of 9,210 bacterial isolates were consecutively collected (1/patient) from 33 US medical centers in 2015–2017 and tested for susceptibility by reference broth microdilution methods in a central laboratory (JMI Laboratories) as part of the International Network for Optimal Resistance Monitoring (INFORM) program. Whole-genome sequencing was performed on carbapenem-resistant Enterobacteriaceae (CRE).ResultsThe most common organisms were S. aureus (SA; 24.3%), E. coli (EC; 20.8%), K. pneumoniae (KPN; 9.1%), coagulase-negative staphylococci (7.3%), E. faecalis (5.5%), P. aeruginosa (PSA; 4.7%), and β-hemolytic streptococci (4.7%). Overall, 50.0% of isolates were Gram-negative bacilli (GNB) and 41.4% were Enterobacteriaceae (ENT). All SA were susceptible (S) to dalbavancin (MIC90, 0.03 μg/mL), linezolid, tigecycline (TGC), and vancomycin; >99.9% S to daptomycin, 97.6% S to ceftaroline, and 57.8% S to oxacillin. The most active agents against ENT were CAZ-AVI (99.9% S; table), amikacin (AMK; 99.7% S), and the carbapenems meropenem (MEM) and doripenem (99.1% S). Ceftolozane-tazobactam (C-T; tested in 2017 only) was active against 96.9% of ENT. Ceftriaxone (CRO)-S rates were 83.0% and 86.5% among EC and KPN, respectively. CRO-non-S KPN exhibited low S rates to most agents, except CAZ-AVI (99.1% S), TGC (93.6%), AMK (93.8%), and colistin (COL; 93.4%). Among 28 CRE isolates (0.7% of ENT), 21 produced a KPC-like, 2 an NMD-like, and 1 a KPC-17 and an NDM-1. COL (100.0% S), C-T (98.7%S), CAZ-AVI (98.2% S), AMK (97.9% S), and tobramycin (95.6% S) were very active against PSA. CAZ-AVI and C-T remained active against most PSA isolates non-S to MEM (93.0 and 95.0% S, respectively) and/or piperacillin–tazobactam (P-T; 88.9 and 91.3% S) and/or CAZ (86.9 and 88.2% S).ConclusionGNB represented 50.0% of bacteria isolated from patients with BSIs and the most active agents against these organisms were CAZ-AVI and AMK. Various agents exhibited excellent overall coverage against Gram-positives, including dalbavancin, daptomycin, linezolid, and TGC. Disclosures H. S. Sader, Allergan: Research Contractor, Research support. R. K. Flamm, Allergan: Research Contractor, Research support. M. A. Pfaller, Allergan: Research Contractor, Research support. M. Castanheira, Allergan: Research Contractor, Research support.

Prevalence of Enterobacteriaceae on fresh produce and food safety practices in small-acreage farms in Tennessee, USA

In spite of the health benefits acquired from produce, microbial safety continues to be a major concern. This study evaluated microbial quality of produce and food safety practices in small-scale farms. Microbial quality of produce from farms was determined by standard and biochemical techniques. Antimicrobial-susceptibility of bacteria was determined by Kirby-Bauer’s disc diffusion method. In addition, questionnaires were developed and distributed to in Middle Tennessee, US growers to capture growers’ practices on the farm. Aerobic plate counts in leafy produce and herbs (5.2–6.1 log CFU/g) were significantly higher (p < 0.05) than that of fruits (3.2–4.0 log CFU/g). Total coliforms in carrots (3.6 CFU/g) were also significantly higher (p < 0.05) than in lettuce (2.9/CFU/g), strawberries (2.5 CFU/g), and apples (2.1 CFU/g). Our results demonstrated that produce harbored diverse bacterial communities which were dominated by Escherichia coli (29.7%), followed by Serratia liquefacians (13%), Klebsiella pneumoniae (11.4%), Proteus mirabilis (10.8%), Pantoea spp. (8.1%), Salmonella (2.7%), Shigella (0.5%), among others. No Escherichia coli O157:H7 was recovered in produce. Bacterial resistance to antibiotics was highest for erythromycin (22.3%), followed by ampicillin (19.6%), streptomycin (12.8%), and amoxicillin (10.3%). About 9% of the farms had food safety plans in place, 31% tested irrigation water annually, and 93% of growers indicated the need for food safety education. Our results indicate that fresh produce from small farms harbor antibiotic resistant bacteria. Food safety education for growers is needed to cause positive changes in food safety awareness and increased adoption of good agricultural practices by small-scale produce growers.

Frequency of Uropathogens and Antimicrobial Susceptibility in Childhood Urinary Tract Infection at Kamenge University Hospital, Bujumbura, Burundi

Background: Increasing resistance to antimicrobials is a worldwide problem. The aim of our study was to determine the pathogens and antimicrobial susceptibility of bacteria causing urinary tract infection (UTI) in children. Methods: This is a prospective cohort study conducted over a 10-month period with 101 children hospitalised at Kamenge University Hospital for acute UTI. The infections were confirmed by Kass urinalysis criteria, and culture and susceptibility antibiotic tests were performed for isolated microbial agents. Results: Frequency of UTI in the overall population of children hospitalised at Kamange University Hospital was 8.4%. Of the 101 children with UTIs, 87 (86.1%) were under the age of 24 months. Diagnosis of pyelonephritis (82%) was the most common, followed by cystitis (18%). Escherichia coli (82%) was the most frequent pathogen causing UTI. We found E coli and Klebsiella pneumonia to be resistant to aminopenicillins (100%), cotrimoxazole (98.2%, 100%), Augmentin (amoxicillin/clavulanic acid) (70.5%, 80%), cefotaxime (45.8%, 28.6%), cefuroxime (36.8 to 45.5%, 50%), fluoroquinolones (33.3 to 53.6%, 28.6 to 50%), gentamicin (27.5%, 20%), and nitrofurantoin (9.3%, 50%). Conclusion: E coli is the main causal agent of UTI in childhood with a high resistance to antibiotics. Appropriate antibiotics for empiric therapy should be based on local circulating bacterial strains and resistance profiles.

Frequency of Uropathogens and Antimicrobial Susceptibility in Childhood Urinary Tract Infection at Kamenge University Hospital, Bujumbura, Burundi.

Background:Increasing resistance to antimicrobials is a worldwide problem. The aim of our study was to determine the pathogens and antimicrobial susceptibility of bacteria causing urinary tract infection (UTI) in children.Methods:This is a prospective cohort study conducted over a 10-month period with 101 children hospitalised at Kamenge University Hospital for acute UTI. The infections were confirmed by Kass urinalysis criteria, and culture and susceptibility antibiotic tests were performed for isolated microbial agents.Results:Frequency of UTI in the overall population of children hospitalised at Kamange University Hospital was 8.4%. Of the 101 children with UTIs, 87 (86.1%) were under the age of 24 months. Diagnosis of pyelonephritis (82%) was the most common, followed by cystitis (18%). Escherichia coli (82%) was the most frequent pathogen causing UTI. We found E coli and Klebsiella pneumonia to be resistant to aminopenicillins (100%), cotrimoxazole (98.2%, 100%), Augmentin (amoxicillin/clavulanic acid) (70.5%, 80%), cefotaxime (45.8%, 28.6%), cefuroxime (36.8 to 45.5%, 50%), fluoroquinolones (33.3 to 53.6%, 28.6 to 50%), gentamicin (27.5%, 20%), and nitrofurantoin (9.3%, 50%).Conclusion:E coli is the main causal agent of UTI in childhood with a high resistance to antibiotics. Appropriate antibiotics for empiric therapy should be based on local circulating bacterial strains and resistance profiles.

Alterations in conjunctival bacteria and antimicrobial susceptibility during topical administration of ofloxacin after cataract surgery in dogs.

OBJECTIVE To evaluate changes in conjunctival bacteria and antimicrobial susceptibility of bacteria after cataract surgery in dogs. ANIMALS 16 client-owned dogs. PROCEDURES Samples for aerobic and anaerobic culture were obtained from the conjunctival fornices of both eyes of dogs 24 hours before (week 0) and 1, 3, and 6 weeks after cataract surgery. Topical administration of ofloxacin (every 6 hours) was initiated 12 hours before surgery and continued for 3 weeks. In vitro antimicrobial susceptibility was determined by Kirby-Bauer disk diffusion and a commercially available test for ofloxacin. RESULTS Frequency of positive culture results was significantly higher at week 6 than at weeks 0 and 1. Bacterial load was more likely to be moderate or high at weeks 3 and 6 than at weeks 0 and 1. The most frequently cultured organism was Staphylococcus pseudintermedius (21/78 [26.9%]), followed by coagulase-negative Staphylococcus spp (19/78 [24.4%]). Staphylococcus pseudintermedius was the organism most frequently cultured at weeks 0 (5/12), 1 (4/12), and 6 (8/19), whereas frequency of this organism was lowest at week 3 (1/20). In contrast, coagulase-negative Staphylococcus spp were the most frequently cultured organisms at week 3 (10/20). There was a significant increase in the proportion of organisms resistant to ofloxacin at week 3, compared with the proportion at week 0. CONCLUSIONS AND CLINICAL RELEVANCE The number of bacterial organisms increased and the population of conjunctival bacteria was altered and had a higher proportion resistant to ofloxacin during the 6 weeks after cataract surgery for dogs treated by use of this protocol.

Prevalence and Antimicrobial Susceptibility of Uropathogens Isolated from Ambulatorial and Nosocomial Infections at Nova Friburgo, Rio de Janeiro, Brazil.

Justificativa e Objetivos: Infecção do Trato Urinário (ITU) é a segunda infecção mais comum, geralmente causada por enterobactérias, principalmente Escherichia coli. Estes microrganismos tem apresentado resistência antimicrobiana para as principais drogas utilizadas para tratar ITU em diferentes partes do mundo. Entretanto, estudos prévios sobre a prevalência e susceptibilidade antimicrobiana regional não foram publicados. Este trabalho objetivou investigar a prevalência e susceptibilidade aos antimicrobianos apresentado por bactérias associadas a ITU de pacientes ambulatoriais ou nosocomiais atendidos ou internados em um hospital em Nova Friburgo, Rio de Janeiro, Brasil. Métodos: Um estudo retrospectivo avaliou a prevalência e a susceptibilidade antimicrobiana de urinoculturas positivas de pacientes ambulatoriais e nosocomiais entre Julho de 2010 a Junho de 2014. Resultados: Dos pacientes ambulatoriais, o microrganismo mais prevalente foi Escherichia coli (76.50%), seguido por Enterobacter sp. (12.02%), e Proteus sp. (5.46%). Nas ITUs nosocomiais, as bactérias mais prevalentes foram E. coli (65.96%), Proteus sp. (7.80%), e Pseudomonas sp. (7.09%). A maioria das urinoculturas positivas foi isolada de mulheres (89.13%). A susceptibilidade antimicrobiana revelou que a maioria de E. coli isolada de pacientes ambulatoriais foi mais resistente à ampicilina (45.00%), ácido nalidíxico (37.14%), nitrofurantoína (35.71%). Dos isolados nosocomiais, E. coli foi mais resistente à ampicilina (56.69%), cefalotina, trimetoprim/sulfametoxazol (43.01%) e ciprofloxacina (33.33%). Conclusão: A resistência antimicrobiana de E. coli foi observada na maioria das ITUs, independente na origem do paciente. Estes resultados contribuirão para melhorar a seleção da terapia antimicrobiana adequada tanto para ITU ambulatorial quanto hospitalar adquiridas em nossa comunidade.

Prevalence and Antimicrobial Susceptibility of E. coli and Salmonella Spp. in Market Show Cattle and Swine

ObjectivesThe objective of this study was to determine the prevalence and antimicrobial susceptibility of generic Escherichia coli and Salmonella spp. in feces of market show steers and hogs from a state wide livestock show.Materials and MethodsFecal samples were collected from market steers (n = 84) and hogs (n = 84) at a statewide livestock show, stored at 4°C and processed within 36 h of collection. Fecal samples were processed using 3M E. coli/Coliform Count Plates for enumeration and isolated onto MacConkey Agar for susceptibility testing. Salmonella prevalence was determined using selective enrichment in Rappaport Vassiliadis and Tetrathionate broths and selective plating on XLT4 agar. Salmonella spp. isolates, which were confirmed positive via latex agglutination, were utilized for antimicrobial susceptibility testing. Antimicrobial susceptibility testing was conducted with a microbroth dilution method using Sensititre plates from Trek Diagnostic. Isolates were tested against 14 antimicrobial agents important to both human and animal health, including: Cefoxitin, Azithromycin, Chloramphenicol, Tetracycline, Ceftriaxone, Amoxicillin/Clavulanic Acid, Ciprofloxacin, Gentamicin, Nalidixic Acid, Ceftiofur, Sulfisoxazole, Trimethoprim/Sulfamethoxazole, Ampicillin, and Streptomycin. Resistance breakpoints used were published in the NARMS 2014 Human Isolates Surveillance Report. Data was analyzed using procedures of SAS (Version 9.1.3; SAS Inst. Inc., Cary, NC).ResultsAs E. coli can serve as a vehicle for resistance genetics, fecal samples were analyzed for its presence and antibiotic resistance. E. coli populations were higher in hogs with 6.12 log10 CFU/g of feces compared to steer samples at 5.57 log10 CFU/g (P < 0.05). Of the 662 E. coli isolates, 98.18% (324 of 330 tested) of hog isolates and 63.25% (210 of 332 tested) of steer isolates exhibited resistance to at least 1 antimicrobial. Within isolates from hogs, the most common resistance was to Tetracycline, Sulfisoxazole, and Streptomycin with 96.67, 69.70, and 53.64% of isolates exhibiting resistance to the respective antimicrobial. Escherichia coli isolates from steers exhibited the most common resistance to Tetracycline, Streptomycin, and Sulfisoxazole with 55.12, 32.53, and 28.61% of isolates exhibiting resistance, respectively.Salmonella was more prevalent in hog samples than steer samples (P < 0.05) with 19.05% of hogs (16 of 84) and 3.61% steers (3 of 83) testing positive. Of the 18 Salmonella isolates from hog samples, 83.33% exhibited resistance to at least 1 antimicrobial. Isolates from market hogs exhibited the most common resistance to Tetracycline, Streptomycin, and Sulfisoxazole with 77.78, 44.44 and 44.44% of isolates resistant to the respective antimicrobial. Conversely, none of the Salmonella isolates from steers exhibited clinical resistance to any of the antimicrobials.ConclusionLittle research has been done on the antimicrobial susceptibility of bacteria in show animals. Results from this study indicate that market show hogs had higher levels the bacteria of interest and isolates from hogs were consistently more resistant to the tested antimicrobial agents when compared to steers. While making up a small percentage of the overall industry, show animals that are designated “market livestock” will eventually be introduced to the human food supply and play a role in its safety.

Antimicrobial susceptibility of uropathogens isolated from Cambodian children

Background: Bacterial resistance to commonly used antimicrobials is an increasing problem in Asia but information concerning the antimicrobial susceptibility of bacteria causing urinary tract infections (UTIs) in children is limited. Methods: This was a 5-year retrospective study of children with suspected UTI attending a paediatric hospital in north-west Cambodia. Urines with a positive culture containing a single organism with a count of >105 colony-forming units (CFU)/ml were considered diagnostic of infection. The organism was identified and the resistance pattern (using CLSI guidelines) and presence of an extended-spectrum β-lactamase (ESBL) phenotype was determined. Results: In total, there were 217 episodes of infection, 210 (97%) with Gram-negative bacteria. Escherichia coli was the most common infecting isolate with high levels of resistance to most oral antibiotics, except nitrofurantoin. Nearly half of the E. coli (44%) were extended-spectrum cephalosporin (ESC)-resistant with the proportion increasing significantly over the 5-year period. ESC-resistant E. coli were more likely to be multi-drug-resistant and 91% demonstrated an ESBL phenotype. Conclusion: The data highlight the importance of microbiological surveillance of UTIs in children, particularly in areas where there are known to be multiply resistant organisms.

Comparison of Disk Diffusion and E-Test with the Reference Method of Microbroth Dilution for Susceptibility Testing of Acinetobacter baumannii Isolates to Tetracyclines

Background and Objective: Due to the continuous increase of multidrug-resistant Acinetobacter baumannii strains around the world, decision making for an effective treatment of infections caused by this organism depends on the results of antimicrobial susceptibility tests. In this study, the validity of disk diffusion and E-test methods was assessed by their comparison with the reference method of microbroth dilution for three antibiotics of tetracycline, doxycycline and minocycline. Methods: Total of 68 A. baumannii isolates were obtained from patients hospitalized in the burn center of Shahid Motahari Hospital in Tehran, Iran. Susceptibility of the Acinetobacter isolates was evaluated using the disk diffusion, E-test and microbroth dilution methods, according to the guidelines of Clinical and Laboratory Standards Institute. Results: Among the isolates, 82.3% were tetracycline-resistant (with minimum inhibitory concentration 50 (MIC50) and MIC90 of 32 and more than 32 µg/ml, respectively and 41.2% were doxycycline-resistant (with MIC50 and MIC90 of 4 and more than 32 µg/ml, respectively). Minocycline, with resistance of up to 13.3% (MIC50 and MIC90 of 1 and 8 µg/ml, respectively) showed the highest antimicrobial activity against the A. baumannii isolates. Antimicrobial susceptibility of bacteria was different depending on the type of methods used. No very major error was observed in any of the methods of susceptibility testing. Overall, the level of major and minor errors in the E-test was lower than the disk diffusion method. Conclusion: The results of this study indicate that minocycline has notably high antimicrobial activity against A. baumannii compared to other antibiotics of the tetracycline group.