Resistance Patterns Of Clinical Isolates Research Articles

Integrons and multidrug resistance across phylogenetic groups of clinical isolates of Escherichia coli.

This study was aimed to investigate the multidrug resistance patterns in clinical isolates of Escherichia coli and their correlation with integrons and phylogenetic groupings. A total of 37 clinical E. coli isolates were evaluated for drug resistance patterns by disk diffusion method. Phylogenetic groupings and the presence of integrons among E. coli were determined by multiplex PCR assays. Multidrug resistance was identified in 84% of the clinical isolates of E. coli with higher resistance found against cephalosporins (94.6%) and fluoroquinolones (83.8%), while lower resistance was observed against polymyxins (24.3%) and carbapenems (29.7%). Metallo-β-lactamases were found in all carbapenem resistant isolates. The phylogenetic group B2 was the most dominant (40.5%), followed by groups A (35.1%), D (13.5%) and B1 (10.8%). Integrons were detected in 25 (67.6%) isolates and intI1, intI2, and intI3 genes were found in 62.2%, 18.9% and 10.8% of isolates respectively. Our results show that phylogenetic classification of E. coli is not relevant with antimicrobial resistance. However, there was strong association between the integron classes and resistance against β-lactam and fluoroquinolones antimicrobials. Additionally, this study highlighted that the presence of integrons plays a crucial role in the development of multidrug resistance in clinical isolates of E. coli. Most significantly, this is the first report of detection of three classes of integron among clinical isolates of E. coli in Pakistan.

Evaluation of antibiotic resistance patterns in clinical isolates of Klebsiella pneumoniae in Bangladesh

The treatment of K. pneumoniae infections has become more difficult due to the emergence of multidrug-resistant strains. This study aimed to evaluate antimicrobial resistance patterns and detect different types of beta-lactamase genes among MDR and non-MDR Klebsiella pneumoniae in various clinical samples. A total of 150 Klebsiella pneumoniae were identified from different clinical samples by conventional microbiological procedures. Antibiotic sensitivity was detected by the Kirby-Bauer disc diffusion method. Extended-spectrum beta-lactamase, Metallo-β-lactamase, and carbapenemase were phenotypically detected by double-disk synergy test, combined disk assay, and modified Hodge test. PCR also detected different β lactamase genes and virulence genes. The majority of Klebsiella pneumoniae were multi-drug resistant (82%). The bacteria were found resistant to most β-lactam antibiotics, aminoglycosides, ciprofloxacin, cotrimoxazole, carbapenem, piperacillin, and tazobactam. However, only about 0.7% colistin resistance was observed. A double-disk synergy test was performed among the isolates for phenotypic detection of ESBL producing Klebsiella pneumoniae. Only 16.6% of isolates were found to be ESBL producers. Among β-lactamase genes, NDM (23.34%), OXA-48(8%), and KPC (7.3%) were detected. Other prevalent β lactamase genes VIM and IMP were not detected. In summary, the prevalence of MDR Klebsiella pneumoniae is high in Bangladesh, which may complicate the treatment of hospitalized patients.

Secrets of the Hospital Underbelly: Patterns of Abundance of Antimicrobial Resistance Genes in Hospital Wastewater Vary by Specific Antimicrobial and Bacterial Family.

Background: Hospital wastewater is a major source of antimicrobial resistance (AMR) outflow into the environment. This study uses metagenomics to study how hospital clinical activity impacts antimicrobial resistance genes (ARGs) abundances in hospital wastewater.Methods: Sewage was collected over a 24-h period from multiple wastewater collection points (CPs) representing different specialties within a tertiary hospital site and simultaneously from community sewage works. High throughput shotgun sequencing was performed using Illumina HiSeq4000. ARG abundances were correlated to hospital antimicrobial usage (AMU), data on clinical activity and resistance prevalence in clinical isolates.Results: Microbiota and ARG composition varied between CPs and overall ARG abundance was higher in hospital wastewater than in community influent. ARG and microbiota compositions were correlated (Procrustes analysis, p=0.014). Total antimicrobial usage was not associated with higher ARG abundance in wastewater. However, there was a small positive association between resistance genes and antimicrobial usage matched to ARG phenotype (IRR 1.11, CI 1.06–1.16, p<0.001). Furthermore, analyzing carbapenem and vancomycin resistance separately indicated that counts of ARGs to these antimicrobials were positively associated with their increased usage [carbapenem rate ratio (RR) 1.91, 95% CI 1.01–3.72, p=0.07, and vancomycin RR 10.25, CI 2.32–49.10, p<0.01]. Overall, ARG abundance within hospital wastewater did not reflect resistance patterns in clinical isolates from concurrent hospital inpatients. However, for clinical isolates of the family Enterococcaceae and Staphylococcaceae, there was a positive relationship with wastewater ARG abundance [odds ratio (OR) 1.62, CI 1.33–2.00, p<0.001, and OR 1.65, CI 1.21–2.30, p=0.006 respectively].Conclusion: We found that the relationship between hospital wastewater ARGs and antimicrobial usage or clinical isolate resistance varies by specific antimicrobial and bacterial family studied. One explanation, we consider is that relationships observed from multiple departments within a single hospital site will be detectable only for ARGs against parenteral antimicrobials uniquely used in the hospital setting. Our work highlights that using metagenomics to identify the full range of ARGs in hospital wastewater is a useful surveillance tool to monitor hospital ARG carriage and outflow and guide environmental policy on AMR.

Antimicrobial Resistance Patterns in Clinical Isolates of Enterobacteriaceae from a Tertiary Care Hospital, Kathmandu, Nepal

Introduction: Multidrug resistance among Enterobacteriaceae is in increasing trend these days. The objective of this study was to determine the antibiogram of clinical isolates of Enterobacteriaceae with special reference to multidrug resistance and extended spectrum beta-lactamases production.Materials and Methods: A descriptive cross sectional study was conducted over a period of six months (February -July, 2017) in the microbiology laboratory of Nepal Medical College Teaching Hospital, Kathmandu, Nepal. A total of 936 bacterial isolates of Enterobacteriaceae from clinical specimens were processed for antimicrobial susceptibility testing and screened for multidrug resistance. ESBL production was detected among potential isolates by combination disk diffusion test.Results: The rate of multidrug resistance and extended spectrum beta-lactamases production was 54.2% and 23.8% respectively. Of the total ESBL producers 92.4% were multidrug resistance. The rate of multidrug resistance and extended spectrum beta-lactamases production were higher in organisms isolated from clinical samples collected from inpatients. High rate of multidrug resistance and extended spectrum beta-lactamases production was seen in E. coli (54.4% &amp; 27.7%), Klebsiella spp. (67.1% &amp; 28.2%) and Citrobacter spp. (70.3% &amp; 10.9%). The antimicrobial resistance rate was highest against ampicillin (76.7%) followed by cefixime (54. 0%), ceftazidime (51.5%), ceftriaxone (51.0%), cotrimoxazole (48.7%), ciprofloxacin (43.9%) and ofloxacin (41.1%).Conclusions: Multidrug resistance is common among Enterobacteriaceae. These bacteria have high rate of resistance against commonly used groups of antibiotics like cephalosporins and quinolones. Continuous monitoring, surveillance of antimicrobial resistance, proper infection control and practices are important to combat with these issues.

Geographic distribution of staphylococcus spp. infections and antimicrobial resistance among dogs from Gauteng Province presented at a veterinary teaching hospital in South Africa

The objective of this study was to investigate spatial patterns of staphylococcal infections and resistance patterns of clinical isolates among dogs from Gauteng province in South Africa. Data from records of 1497 dog clinical samples submitted to a veterinary teaching hospital between 2007 and 2012 were used in the study. Spatial empirical Bayesian smoothed risk maps were used to investigate spatial patterns of staphylococcal infections, antimicrobial resistance (AMR), and multidrug resistance (MDR). Moran's I and spatial scan statistics were used to investigate spatial clusters at municipal and town spatial scales. Significant clusters of staphylococcal infections were identified at both the municipal (Relative Risk [RR] = 1.71, p = 0.003) and town (RR = 1.65, p = 0.039) scales. However, significant clusters of AMR (p = 0.003) and MDR (p = 0.007) were observed only at the town scale. Future larger studies will need to investigate local determinants of geographical distribution of the clusters so as to guide targeted control efforts.

Relationship between Antibiotic Resistance Patterns and Coagulase in Clinical Isolates of Staphylococcus aureus in Nowshahr and Chalous

Background: Staphylococcus aureus is one of the main agents of nosocomial infections. Identifying coagulase enzyme in staphylococcal infections is of great importance as it is one of the main virulence agents. The present study aims to accurately detect the presence of coagulase gene and its relationship with antibiotic resistance patterns in clinical isolates. Methods: In this experimental study, a total of 20 clinical samples of S. aureus and 10 clinical samples of coagulase-negative staphylococci were collected and identified from hospitals and laboratories in Nowshahr and Chalous. Antibiotic resistance patterns of isolates were examined based on CLSI and finally polymerase chain reaction was used in order to detect the presence of coagulase gene with specific primers. Treatments were examined in three intervals and the results were analyzed using one-way analysis of variance (ANOVA), univariate ANOVA, and t-test at the probability level of P < 0.05. Moreover, the comparison of means was presented using Duncan’s multiple range tests (P < 0.05). All the statistical analyses were carried out using SPSS (V. 16). Results: Suggested that isolates showed phenotypic presence of coagulase enzyme and had this gene genotypically as well. Coagulase-positive samples demonstrated higher resistance to tetracycline 20%, oxacillin 55%, gentamicin 20%, and kanamycin 25%. Statistically, there was no significant difference among inhibition zone diameters of oxacillin, nalidixic acid, gentamicin, kanamycin, and penicillin. Conclusions: Coagulase gene causes antibiotic resistance and coagulase-negative staphylococci are spreading rapidly and their resistance is increasing.

Phenotypic characterization of macrolide and lincosamide resistance patterns in clinical isolates of staphylococci

Introduction: The macrolide, lincosamides, and streptogramin (MLS) group of antibiotics are one of the few alternative antibiotics available for the treatment of methicillin-resistant staphylococcal isolates. Clinical failures with these antibiotics have been reported because of the usage of these drugs in improperly characterized and tested isolates. The purpose of this study was to know the prevalence of different phenotypes in our area, with an emphasis on inducible resistance detection. Materials and Methods: A total of 100 methicillin-resistant staphylococcal isolates were included in the study. Phenotypic characterization was done by using erythromycin and clindamycin disks kept at a distance of 15 mm on the Muller Hinton agar plate and incubating at 24 h. Results: Among 100 isolates, 23 were sensitive to both erythromycin and clindamycin (S phenotype). Thirty-one isolates were resistant to erythromycin but sensitive to clindamycin (MS phenotype). Inducible resistance (iMLSB) was seen in 26 of the total isolates. Isolates which were resistant to both the antibiotics numbered 19 (cMLSB). There was only one isolate which was sensitive to erythromycin but resistant to clindamycin (L phenotype). Conclusion: MLS group of antibiotics is still an effective group of antibiotics against methicillin-resistant staphylococcal isolates, and routine testing for the inducible resistance in these isolates will help in the prevention of therapeutic failure and for the better management of the patient.

Resistance patterns in clinical isolates of pathogenic Actinomyces species.

Actinomyces spp. are commensals that may occasionally invade deep tissue structures, causing difficult-to-treat and disfiguring lesions. Information on antimicrobial resistance patterns is limited to observations from two previous studies. Therefore, we examined antimicrobial resistance patterns in clinical isolates of Actinomyces spp. In this retrospective assessment of antimicrobial resistance patterns, we identified 392 Actinomyces spp. at a tertiary care centre from January 2008 to December 2014. MICs of various antimicrobial agents, including ampicillin/sulbactam, meropenem, clindamycin, metronidazole and vancomycin for anaerobic actinomycetes, were obtained by Etest. For aerobic actinomycetes, imipenem, cefotaxime, amikacin, linezolid, moxifloxacin, trimethoprim/sulfamethoxazole and clarithromycin were tested. MIC results were interpreted based on guidelines published by the CLSI (formerly NCCLS). Actinomyces meyeri was predominantly isolated and accounted for 34% of all Actinomyces spp. identified, followed by Actinomyces turicensis with 23%. Actinomyces neuii is considered to be a rare Actinomyces sp., but accounted for 8% of isolates. Antimicrobial susceptibility testing of isolates showed that the Actinomyces spp. were almost uniformly susceptible to β-lactam antimicrobials (with and without β-lactamase inhibitors), carbapenems, tetracyclines and vancomycin. In contrast, Actinomyces spp. isolates were almost uniformly resistant to metronidazole. β-Lactam antimicrobial agents remain the first choice, whereas metronidazole should be avoided, in the treatment of actinomycosis. Reasonable alternatives for treatment are tetracyclines and carbapenems.

The need for continued monitoring of antibiotic resistance patterns in clinical isolates of Staphylococcus aureus from London and Malta.

BackgroundAntibiotic resistance is an increasing problem in isolates of Staphylococcus aureus (S. aureus) worldwide. In 2001 The National Health Service in the UK introduced a mandatory bacteraemia surveillance scheme for the reporting of S. aureus and methicillin-resistant S. aureus (MRSA). This surveillance initiative reports on the percentage of isolates that are methicillin resistant. However, resistance to other antibiotics is not currently reported and therefore the scale of emerging resistance is currently unclear in the UK. In this study, multiple antibiotic resistance (MAR) profiles against fourteen antimicrobial drugs were investigated for 705 isolates of S. aureus collected from two European study sites in the UK (London) and Malta.ResultsAll isolates were susceptible to linezolid, teicoplanin and vancomycin. Multiple antibiotic resistance profiles from both countries were determined, a total of forty-two and forty-five profiles were seen in the UK cohort (MRSA and MSSA respectively) and comparatively, sixty-two and fifty-two profiles were shown in the Maltese group. The largest MAR profile contained six antibiotics (penicillin G, methicillin, erythromycin, ciprofloxacin, clindamycin and clarithromycin) and was observed in the MRSA isolates in both the UK and Maltese cohorts.ConclusionThe data presented here suggests that the monitoring of changing resistance profiles locally in maintaining treatment efficacy to resistant pathogens.

Antibiotic resistance among enterococcal strains isolated from clinical specimens

The distribution and resistance patterns of clinical isolates of enterococci from hospital patients were compared with those obtained from outpatients. Of 235 enterococcal isolates 212 (90.2%) were identified as Enterococcus faecalis and 23 (9.8%) as E. faecium. E. faecium occurred more frequently in specimens from hospitalized patients than from outpatients ( P<0.001). Over 90% of all E. faecalis isolates were susceptible to ampicillin. Resistance to ampicillin occurred in 66.7% of hospital strains of E. faecium. High-level resistance to gentamicin (MIC>500 mg/l) was seen in 37.03% of inpatients’ and in 11.5% of outpatients’ E. faecalis isolates and in 76.2% of hospital isolates of E. faecium. High-level streptomycin resistance (MIC>2000 mg/l) occurred in 52.8% of E. faecalis and 76.2% of E. faecium hospital isolates. There were no isolates resistant to vancomycin. The community acquired strains isolated from outpatients were more susceptible than isolates from hospitalized patients to all antimicrobial agents tested.

Antibiotic resistance patterns of enterococci and occurrence of vancomycin-resistant enterococci in raw minced beef and pork in Germany.

The food chain, especially raw minced meat, is thought to be responsible for an increase in the incidence of vancomycin-resistant enterococci (VRE) in human nosocomial infections. Therefore, 555 samples from 115 batches of minced beef and pork from a European Union-licensed meat-processing plant were screened for the occurrence of VRE. The processed meat came from 45 different slaughterhouses in Germany. Enterococci were isolated directly from Enterococcosel selective agar plates and also from Enterococcosel selective agar plates supplemented with 32 mg of vancomycin per liter. In addition, peptone broth was used in a preenrichment procedure, and samples were subsequently plated onto Enterococcosel agar containing vancomycin. To determine resistance, 209 isolates from 275 samples were tested with the glycopeptides vancomycin, teicoplanin, and avoparcin and 19 other antimicrobial substances by using a broth microdilution test. When the direct method was used, VRE were found in 3 of 555 samples (0.5%) at a concentration of 1.0 log CFU/g of minced meat. When the preenrichment procedure was used, 8% of the samples were VRE positive. Our findings indicate that there is a low incidence of VRE in minced meat in Germany. In addition, the resistance patterns of the VRE isolates obtained were different from the resistance patterns of clinical isolates. A connection between the occurrence of VRE in minced meat and nosocomial infections could not be demonstrated on the basis of our findings.

Identification and antimicrobial resistance patterns of clinical isolates of Clostridium clostridioforme, Clostridium innocuum, and Clostridium ramosum compared with those of clinical isolates of Clostridium perfringens

Clostridium ramosum, C. innocuum, and C. clostridioforme are frequently isolated from clinical specimens including blood. Because of Gram stain variability, a lack of spores, and atypical colonial morphology, identification of these species is often difficult. Three anaerobe identification kits were evaluated for their abilities to identify these species. For comparison, 11 strains of C. perfringens were evaluated in parallel. By using profile numbers and codebooks, the correct genus and species were identified, as follows: with the RapID ANA II kit, 100% (20 of 20) of C. ramosum isolates, 24% (5 of 21) of C. innocuum isolates, and 50% (10 of 20) of C. clostridioforme isolates; with the AnIDent kit, 60% (12 of 20) of C. ramosum isolates, 28% (6 of 21) of C. innocuum isolates, and 90% (18 of 20) of C. clostridioforme isolates; with the ATB32A kit, 70% (14 of 20) of C. ramosum isolates, 0% (0 of 21) of C. innocuum isolates, and 40% (8 of 20) of C. clostridioforme isolates. Profile numbers that overlapped several species were obtained as follows: with the RapID ANA II kit, 0% of C. ramosum isolates, 76% of C. innocuum isolates, and 40% of C. clostridioforme isolates; with the AnIDent kit 40% of C. ramosum isolates, 62% of C. innocuum isolates, and 5% of C. clostridioforme isolates; with the ATB32A kit, 15% of C. ramosum isolates, 52% of C. innocuum isolates, and 25% of C. clostridioforme isolates. One strain of C. innocuum was misidentified by the AnIDent kit, and the remainder yielded profile numbers that were not listed in the codebooks. The MICs of 11 antimicrobial agents including penicillin G, metronidazole, clindamycin, cefoxitin, cefotetan, imipenem, meropenem, amoxicillin-clavulanate, ampicillin-sulbactam, piperacillin-tazobactam, and vancomycin were determined by the agar dilution method. All C. perfringens strains were susceptible to all antimicrobial agents tested. Various levels of resistance to cefoxitin, cefotetan, and penicillin G were noted with C. ramosum, C. clostridioforme, and C. innocuum. In addition, resistance to clindamycin was noted with C. ramosum (5%) and C. innocuum (10%). Most strains of C. innocuum were only moderately susceptible to vancomycin (MIC at which 90% of strains are inhibited, 4 micrograms/ml).

Didanosine and zidovudine resistance patterns in clinical isolates of human immunodeficiency virus type 1 as determined by a replication endpoint concentration assay.

Reports of in vitro resistance of human immunodeficiency virus type 1 (HIV-1) to zidovudine (AZT) have raised concerns about the development of resistance to other dideoxynucleosides in clinical use. To address this, we have developed a screening assay which supports the growth of clinical isolates and have applied this to a series of paired isolates from patients entered into a phase I trial of didanosine (DDI). Thirteen patients (10 with AIDS, 3 with AIDS-related complex) who had been exposed to AZT for a mean of 6.5 months (range, 1 to 13 months) were treated with DDI at 750 mg/day. Paired isolates were obtained pretherapy and after a mean of 58 weeks (range, 21 to 90) of DDI therapy by coculture of peripheral blood mononuclear leukocytes (PBLs) with phytohemagglutinin-stimulated donor PBLs. Isolates were passaged only one additional time in PBLs and then tested in parallel in a microtiter assay with phytohemagglutinin-stimulated donor PBLs as targets. PBLs were infected with 10(5) 50% tissue culture infectious doses per 10(7) cells and exposed to DDI (1 to 50 microM) or AZT (0.01 to 100 microM), and supernatants were assayed for the HIV p24 antigen at 7 days postinfection. Control AZT-susceptible and resistant isolates were included. The median pre- and posttherapy DDI susceptibilities of the 13 pairs of isolates were 10.0 microM (range, 1 to 25 microM) and 17.5 microM (range, 2.5 to 50 microM), respectively (P = 0.036; Wilcoxon signed-rank test). These studies thus indicated that (i) the susceptibility to DDI tends to mildly decrease with drug exposure; (ii) the susceptibility to AZT improves with time off AZT; (iii) baseline susceptibilities to DDI have a wide range, and the CD4 response may correlate with the initial susceptibility; and (iv) a PBL-based microtiter assay is useful for screening clinical isolated for dideoxynucleoside susceptibility profiles.

Acquisition of Resistance to Beta-Lactams by Enterobacter cloacae and Serratia marcescens in the Clinical Field.

We compared the drug resistance patterns of clinical isolates of Enterobacter cloacae and Serratia marcescens in 1983 and 1990 at Nagasaki University Hospital. Furthermore, beta-lactamase production by drug-resistant strains of several organisms was investigated. In 1990, the number of E.cloacae or S. marcescens strains isolated was about half of that in 1983. Most of the E.cloacae strains were isolated from the respiratory tract in both years. A large proportion of S. marcescens strains were isolated from the urinary tract in 1983, but in 1990 these strains were isolated from the respiratory tract. An increase in E. cloacae strains and S. marcescens strains resistant to ceftizoxime or to latamoxef was not noted when comparing 1990 with 1983. The beta-lactamase prepared from resistant strains isolated in 1990 showed a higher potency than that from susceptible strains isolated in the same year, and a larger amount of betalactamase was produced by the resistant strains. Beta-lactamase production by resistant strains of E. cloacae, Citrobacter freundii, and S. marcescens was found to be due to derepression. These strains resistant to beta-lactams were susceptible to imipenem.