Outbreak caused by multidrug-resistant OXA-48 and NDM-1 producing Klebsiella pneumoniae in the intensive care unit of a cancer hospital.

We report a nosocomial outbreak caused by a multidrug-resistant carbapenemase-producing Klebsiella pneumoniae (MDRCPKp), that was detected in six patients admitted to the medical intensive care unit between 20th of December 2023 and 15th of January 2024 in Ankara, Turkey. The investigation of this outbreak was started on 29th of December 2023. During the outbreak 11 samples were collected from the six patients with MDRCPKp. Pulsed-field gel electrophoresis (PFGE) was performed to determine the genetic relatedness and clonality of MDRCPKp strains. MDRCPKp was isolated in the tracheal aspiration culture, blood, urine, and screening samples. Five patients with MDRCPKp colonization developed healthcare-associated infection. In one patient MDRCPKp was isolated from tracheal aspirate and the screening cultures were considered as colonization not infection. PFGE analysis revealed that all isolates belonged to the same K. pneumoniae clone. MDRCPKp strain of this outbreak exhibited multidrug resistance and co-produced OXA-48 and NDM-1. This outbreak ended after application of strict infection control measures. An outbreak of MDRCPKp can occur in hospitals, especially in the intensive care units; thus, it should be detected early by infection control teams. A strong collaboration between infection control team and microbiology laboratory is essential to cope with MDR bacterial outbreaks in hospitals.

Early identification of the nosocomial spread of vancomycin-resistant Enterococcus faecium by Fourier-transform infrared spectroscopy and performance comparison with PFGE and WGS.

Early detection of disseminating vancomycin-resistant Enterococcus faecium (VREfm) in ICU wards is crucial for outbreak identification and the implementation of prompt infection control measures. Genotypic methods like pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS) are costly and time-consuming, hindering rapid response due to batch dependency. Fourier-transform infrared spectroscopy (FT-IR) offers the potential for real-time outbreak detection and reliable strain typing. We utilized FT-IR to identify clonal VREfm dissemination and compared its performance to PFGE and WGS. Between February through October 2023, an unusually high number of VREfm were recovered at a tertiary hospital in Barcelona. Isolates were examined for antimicrobial susceptibility, carriage of vanA/vanB genes and clonality was also studied using FT-IR, PFGE, and WGS. Routine FT-IR inspections revealed recurring VREfm clustering during the outbreak's initial weeks. In total, 104 isolates were recovered from 75 patients and from multiple wards. However, only one isolate was recovered from an environmental sample, suggesting the absence of environmental reservoirs. An ST80 vancomycin-resistant (vanA) E. faecium strain was the main strain responsible for the outbreak, although a few additional VREfm strains were also identified, all belonging to CC17. PFGE and cgMLST (WGS) yielded identical clustering results to FT-IR, and WGS confirmed vanA/vanB gene carriage in all VREfm isolates. Infection control measures led to a rapid decline in VREfm isolates, with no isolates detected in November. FT-IR spectroscopy offers rapid turnaround times, sensitivity, and reproducibility, comparable to standard typing methods. It proved as an effective tool for monitoring VREfm dissemination and early outbreak detection.

Molecular typing of reduced susceptibility of Acinetobacter calcoaceticus-baumannii complex to Chlorhexidine in Turkey by pulsed-field gel electrophoresis.

Introduction. The global spread of Acinetobacter spp., particularly the Acinetobacter calcoaceticusbaumannii (ACB) complex, has led to its recognition as a significant pathogen by the World Health Organization (WHO). The increasing resistance of the ACB complex to multiple antibiotics presents a challenge for treatment, necessitating accurate antibiotic susceptibility profiling after isolation.Hypothesis or gap statement. There is limited understanding of the antimicrobial resistance and chlorhexidine, a biocide, susceptibility profiles of ACB complex strains, especially in clinical settings in Turkey.Aim. This study aimed to identify ACB complex strains recovered from various clinical specimens at Hacettepe University Hospitals in Ankara, Turkey, in 2019, and to assess identification, their antibiotic and chlorhexidine susceptibility profiles, and genomic relatedness.Methodology. Eighty-two ACB complex strains were identified using MALDI-TOF MS. Susceptibility testing to 12 antibiotics was conducted using the disc diffusion method, and colistin, chlorhexidine susceptibility was assessed using the broth microdilution technique, following the latest EUCAST and CLSI guidelines. ACB complex members with reduced chlorhexidine sensitivity were further analyzed by pulsed-field gel electrophoresis (PFGE) for bacterial typing.Results. Among the isolates, 1.2% were multidrug-resistant (MDR), 73.2% were extensively drug-resistant (XDR), and 12.2% were pandrug-resistant (PDR). Carbapenem resistance was found in 86.7% of MDR, PDR, and XDR strains. Colistin resistance was observed in 15.8% of isolates, and 18.2% exhibited decreased susceptibility to chlorhexidine. PFGE revealed seven different clones among strains with reduced chlorhexidine sensitivity, indicating vertical transmission within the hospital.Conclusion. This study highlights the reduced susceptibility to chlorhexidine in ACB complex members and provides epidemiological insights into their spread. The findings underscore the importance of screening for antimicrobial resistance and biocide susceptibility profiles to effectively manage healthcare-associated infections.

Genetic characterization of vancomycin-resistant Enterococcus faecium isolates from neutropenic patients in Tunisia: spread of the pandemic CC17 clone associated with high genetic diversity in Tn1546-like structures.

AIMS: In Tunisia, limited research has focused on characterizing clinical vancomycin-resistant Enterococcus faecium (VREfm). This study aimed to bridge this knowledge gap by molecular characterization of antimicrobial resistance, determining the genetic elements mediating vancomycin-resistance, and whole-genome sequencing of one representative VREfm isolate. METHODS AND RESULTS: Over 6 years (2011-2016), a total of eighty VREfm isolates responsible for infection or colonization were identified from hospitalized patients, with the incidence rate increasing from 2% in 2011 to 27% in 2016. All of these strains harbored the vanA gene. The screening for antimicrobial resistance genes revealed the predominance of ermB, tetM, and aac(6')-Ie-aph(2'')-Ia genes and 81.2% of strains harbored the Tn1545. Pulsed-field gel electrophoresis identified seven clusters, with two major clusters (belonging to ST117 and ST80) persisting throughout the study period. Seven Tn1546 types were detected, with type VI (truncated transposon) being the most prevalent (57.5%). Whole-genome sequencing revealed a 3 028 373 bp chromosome and five plasmids. Mobile genetic elements and a type I CRISPR-cas locus were identified. Notably, the vanA gene was carried by the classic Tn1546 transposon with ISL3 insertion on a rep17pRUM plasmid. CONCLUSION: A concerning trend in the prevalence of VREfm essentially attributed to CC17 persistence and to horizontal transfer of multiple genetic variants of truncated vanA-Tn1546.

Analysis of in vitro expression of virulence genes related to antibiotic and disinfectant resistance in Escherichia coli as an emerging periodontal pathogen.

The collective involvement of virulence markers of Escherichia coli as an emerging pathogen associated with periodontitis remains unexplained. This study aimed to implement an in vitro model of infection using a human epithelial cell line to determine the virulome expression related to the antibiotic and disinfectant resistance genotype and pulse field gel electrophoresis (PFGE) type in E. coli strains isolated from patients with periodontal diseases. We studied 100 strains of E. coli isolated from patients with gingivitis (n = 12), moderate periodontitis (n = 59), and chronic periodontitis (n = 29). The identification of E. coli and antibiotic and disinfectant resistance genes was performed through PCR. To promote the expression of virulence genes in the strains, an in vitro infection model was used in the human epithelial cell line A549. RNA was extracted using the QIAcube robotic equipment and reverse transcription to cDNA was performed using the QuantiTect reverse transcription kit (Qiagen). The determination of virulence gene expression was performed through real-time PCR. Overall, the most frequently expressed adhesion genes among the isolated strains of gingivitis, moderate periodontitis, and chronic periodontitis were fimH (48%), iha (37%), and papA (18%); those for toxins were usp (33%); those for iron acquisition were feoB (84%), fyuA (62%), irp-2 (61%), and iroN (35%); those for protectins were traT (50%), KpsMT (35%), and ompT (28%); and those for pathogenicity islands were malX (45%). The most common antibiotic and disinfectant resistance genes among gingivitis, moderate periodontitis, and chronic periodontitis strains were sul-2 (43%), blaSHV (47%), blaTEM (45%), tet(A) (41%), dfrA1 (32%), marR-marO (57%), and qacEA1 (79%). The findings revealed the existence of a wide distribution of virulome expression profiles related to the antibiotic and disinfectant resistance genotype and PFGE type in periodontal strains of E. coli. These findings may contribute toward improving the prevention and treatment measures for periodontal diseases associated with E. coli.

Comparison of CRISPR typing and conventional molecular methods for distinguishing Laribacter hongkongensis isolates from fish, frogs and humans.

High-resolution and efficient typing for Laribacter hongkongensis (L. hongkongensis) is essential for epidemiological investigation of such emerging foodborne pathogens. Clustered regularly interspaced short palindromic repeats (CRISPR) typing is an innovative molecular method that shows great promise for L. hongkongensis typing. Here, we explored the CRISPR typing method by combining CRISPR1 and CRISPR2 loci to characterize a collection of 109 L. hongkongensis isolates from humans and animals and compared it to current molecular methods such as pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The results showed that all three methods have high discriminatory power (diversity index was 0.9902 for PFGE, 0.9663 for CRISPR and 0.9562 for MLST); strong congruence was observed between them (Rand index was 0.969 between CRISPR and PFGE, 0.953 between CRISPR and MLST, 0.958 between PFGE and MLST). CRISPR typing could well distinguish the isolates in the same STs or PFGE profiles, and the genetic information contained by the CRISPR array is useful for deep phylogenetic typing. We demonstrate that rapid CRISPR typing is a practical genetic fingerprinting tool with high resolution, comparable ease of use and lower cost, ability to track the source of various groups of L. hongkongensis strains and indication of genetic characteristics.

Homology of Escherichia coli isolated from urine and vagina and their antimicrobial susceptibility in postmenopausal women with recurrent cystitis.

Uropathogenic Escherichia coli (UPEC) is a typical cystitis-causing organism that can migrate from the vagina to the bladder and cause recurrent cystitis (RC). Few reports have compared the characteristics of urinary and vaginal UPEC in patients with RC. We carried out molecular biological analyses of Escherichia coli (E. coli) strains and their antimicrobial susceptibility to assess the association between urinary and vaginally UPEC. We included E. coli isolated from urinary and vaginal samples at the onset of cystitis in postmenopausal women with RC between 2014 and 2019 in our hospital. Pulsed-field gel electrophoresis (PFGE) was performed using a restriction enzyme (Xba I). These sequences were compared with 17 antimicrobial susceptibilities determined by a micro-liquid dilution method. Multilocus sequence typing (MLST) and classification of extended-spectrum ß-lactamase (ESBL) genotypes by multiplex polymerase chain reaction (PCR) were performed on ESBL-producing E. coli. We analyzed 14 specimens (each seven urine and vaginal) from seven patients in total. On PFGE, the similarity of urinary and vaginal E. coli per patient ranged from 89.5 to 100 %, including four patients with 100 % matches. MLST demonstrated that 29 % (4/14 specimens) were strain sequence type 131. Two specimens contained ESBL-producing strains and identified the CTX-M-27 genotype for each specimen. For each patient, antimicrobial susceptibilities between urinary and vaginal E. coli were mostly identical. Thus, urinary- and vaginally-derived E. coli were identical in postmenopausal women with RC. Management targeting both urinary and vaginal UPEC is essential for RC, indicating the importance of a vagina-targeted approach.

Outbreak of Burkholderia cenocepacia in an intensive care unit of a tertiary care hospital identified by pulsed-field gel electrophoresis.

Nosocomial outbreaks of Burkholderia cepacia complex, transmitted through contaminated medical surfaces or equipment have been reported. Pulsed-field Gel Electrophoresis (PFGE) is recognized as the "gold standard" for molecular subtyping, yet studies on clonal relationships in India are limited. PFGE was used to study the clonal relationships of 22 isolates of Burkholderia cenocepacia from 12 patients admitted to a critical care unit during 2 months (November and December 2021). PFGE revealed three different profiles with 15 isolates belonging to a single cluster suggesting a common source within the hospital, emphasizing the need for preventive measures to control B. cenocepacia transmission.

Multicenter retrospective genomic characterization of carbapenemase-producing Acinetobacter baumannii isolates from Jiangxi patients 2021-2022: identification of a novel international clone, IC11.

This study aimed to characterize carbapenem-resistant Acinetobacter baumannii (CRAB) isolates from Jiangxi patients using whole-genome sequencing (WGS). We subjected 100 clinical CRAB strains isolated from the three local largest teaching hospitals to WGS and antimicrobial susceptibility testing. Molecular epidemiology was investigated using multilocus sequence typing, core genome multilocus typing, core genome single-nucleotide polymorphism phylogeny, and pulsed-field gel electrophoresis. The most prevalent acquired carbapenemase was blaOXA-23, predominant in all isolates (100%). Isolates belonging to the dominating international clone IC2 accounted for 92% of all isolates. International IC11 (ST164Pas/ST1418Ox) clone was found in an additional 8% (eight isolates), with seven isolates (87.5%) carrying an acquired additional blaNDM-1 carbapenemase. The oxa23-associated Tn2009, either alone or in a tandem repeat structure containing four copies of blaOXA-23, was discovered in 62% (57 isolates) of IC2. The oxa23-associated Tn2006 was identified in 38% (35 isolates) of IC2 and all IC11 isolates. A putative conjugative RP-T1 (formerly RepAci6) plasmid with blaOXA-23 in Tn2006 within AbaR4, designated pSRM1.1, was found in IC2 A. baumannii strain SRM1. The blaNDM-1 gene found in seven IC11 isolates was located on a novel Tn6924-like transposon, a first-time report in IC11. These findings underscore the significant importance of real-time surveillance to prevent the further spread of CRAB. IMPORTANCE: Carbapenem-resistant Acinetobacter baumannii (CRAB) is notorious for causing difficult-to-treat infections. To elucidate the molecular and clinical epidemiology of CRAB in Jiangxi, clinical CRAB isolates were collected and underwent whole-genome sequencing and antibiotic susceptibility phenotyping. Key findings included the predominance of OXA-23-producing IC2 A. baumannii, marked by the emergence of OXA-23 and NDM-1-producing IC11 strains.

Mapping Heterogeneous Population Structure of Mannheimia haemolytica Associated with Pneumonic Infection of Sheep in Southern State Karnataka, India.

Mannheimia haemolytica is recognized as principal pathogen associated with pneumonic pasteurellosis leading to huge economic losses to small ruminant farmers. Even though the disease causes huge economic losses, epidemiology of M. haemolytica is less studied, hindering the formulation of effective control strategies. Current study aimed to highlight molecular characterisation of M. haemolytica strains isolated from ovine pneumonic infection. M. haemolytica 27 isolates with two reference strains were characterised using capsular and virulence gene typing, multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) methods. M. haemolytica serotype A2 recognized as predominant serotype (74%) followed by A6 (11%) and A1 (5%) serotypes. Virulence gene profiling by PCRs showed dominance of all five virulent genes [such as adh and gcp (100% each)] followed by gs60 (88.8%), lktC (85.2%), tbpB (51.9%) and least nmaA gene (14.8%). MLST profiling delineated M. haemolytic isolates into 11 sequence types (STs) with most prevalent being ST37 (27.9%) and ST16 (23%) and nine new STs (ST37, 38, 39, 40, 41, 42, 47, 48, and 49). These new STs did not belong to any of the three clonal complexes (CC4, CC8 and CC28). ST16 was exclusively noted in A1 and A6 serotypes. Amongst 25 isolates, 22 pulsotypes (GD 0.88) recorded indicated variability of the M. haemolytica isolates in PFGE analysis. In conclusion, the study suggested dominance of M. haemolytica serotype A2 harbouring different virulent genes, diverse STs and pulsotypes responsible for pneumonic pasteurellosis frequently encountered in sheep.

Customizable BAC-based DNA markers for pulsed-field gel electrophoresis.

DNA markers are used as a size reference and sample loading control during gel electrophoresis. Most markers are designed for conventional gel electrophoresis to separate DNA smaller than 20 kb. For larger molecules, pulsed-field gel electrophoresis (PFGE) marker is required. Limited PFGE markers are available because large DNA are prone to nicking and degradation, causing smeary bands. Here, we developed a robust marker based on bacterial artificial chromosomes (BACs) with bands up to 184 kb. This marker could consistently confer intense and distinct bands for accurate gel analysis in molecular biology studies, laboratory validations or clinical diagnosis.

Epidemiological Characteristics of Shiga Toxin-Producing Escherichia coli Responsible for Infections in the Polish Pediatric Population.

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens causing hemorrhagic colitis and hemolytic uremic syndrome (HUS) in children and the elderly. Stool samples were collected from 180 children hospitalized in five pediatric centers in Poland in 2018-2022. Direct stx1/stx2 gene detection by PCR in feces and E. coli isolates was performed. Antibiotic susceptibility was tested according to EUCAST v.12. Randomly selected isolates were serotyped with O157 antiserum and genotyped by pulsed-field gel electrophoresis (PFGE). A total of 44 E. coli isolates were confirmed as STEC by PCR. Among them, 84.4% were positive for stx2, and equally 6,8% for only stx1 and both stx1 and stx2 genes. The stx1 gene was also found in one Citrobacter freundii isolate. E. coli serotype O157 was present in 97.6% of the isolates. STEC infections most often occurred between June-October with a peak in July and August (51%). The highest, 77.8% of STEC isolates were found in the 1-5 years old group. No extended-spectrum ß-lactamases (ESBL) were found. Resistance only to amoxicillin/clavulanic acid (24.4%), piperacillin/tazobactam (3%), cefotaxime (6%), gentamicin (6%), ciprofloxacin (3%), azithromycin (3%), trimethoprim/sulfamethoxazole (24,2%) was detected. PFGE analysis showed 18 PFGE types with no clonal distribution. Eight isolates with A, B, and C PFGE types showed genetic relatedness in the type with no detection of transmission way of distribution. STEC strains pose a serious threat to human health, therefore demographic and epidemiological characteristics are crucial for their surveillance.

Phenotypic and molecular characterisation of Salmonella spp. isolates in healthy poultry.

1. Epidemiological surveillance of Salmonella spp. serves as a primary tool for maintaining the health of poultry flocks. Characterising circulating serotypes is crucial for implementing control and prevention measures. This study conducted phenotypic and molecular characterisation of S. enterica Pullorum, S. enterica Heidelberg, and S. enterica Corvalis isolated from broiler chickens during slaughtering.2. All strains were susceptible to gentamicin, neomycin and norfloxacin. However, resistance rates exceeded 50% for ciprofloxacin and tiamulin, irrespective of the serotype. Approximately 64% of strains were classified as multidrug-resistant, with S. enterica Heidelberg strains exhibiting significantly higher overall resistance. The isolates demonstrated the ability to adhere and produce biofilm at a minimum of three temperatures, with S. enterica Pullorum capable of biofilm production at all temperatures encountered during poultry rearing.3. Each strain possessed between two and seven different virulence-associated genes. Genetic similarity, as indicated by pulsed field gel electrophoresis, exceeded 90% for all three serotypes and strains were classified in the R5 ribotype by PCR, regardless of serotype. Sequencing revealed high similarity among all strains, with homology ranging from 99.61 to 100% and all were classified to a single cluster.4. The results suggested a clonal relationship among the strains, indicating the possible circulation of a unique clonal group of S. enterica Pullorum in the southern region of Brazil.

Genetic relatedness, antibiotic resistance, and virulence of Klebsiella pneumoniae isolated from health care and food sources in Wuhan, China.

BACKGROUND: To investigate genetic relatedness and antibiotic resistance of Klebsiella pneumoniae from retail meat samples, clinical source samples, and hospital environmental samples in Wuhan, China. METHODS: Hypermucoviscosity and biofilm formation of K. pneumoniae were assessed by string test and crystal violet staining. MICs of 18 antimicrobials were determined by broth microdilution. PCR detected 14 antibiotic resistance genes. Genetic relatedness and clonal dissemination were analyzed by PFGE. RESULTS: Among 5,730 samples, 46 were tested positive for K pneumoniae, with higher rates observed in meat (23.4%) than in clinical samples (0.6%) and hospital environmental samples (8.0%). Meat-derived isolates showed high resistance to tetracycline (36.4%, 4/11), sulfonamide (27.3%, 3/11), and gentamicin (27.3%, 3/11), whereas clinical isolates exhibited significant resistance to ampicillin-sulbactam (32.3%, 10/31). Multidrug resistance was observed in 17.4% (8/46) of the isolates, particularly in hospital environmental samples (3/4). Biofilm production was observed in 88.1% (37/42) of K pneumoniae. Pulsed-field gel electrophoresis analysis revealed patient-to-patient K pneumoniae transmission, transmission between patients and hospital environment, as well as cross-contamination between markets. CONCLUSIONS: The findings underscore the importance of comprehensive surveillance, infection control, and judicious antibiotic use in mitigating the impact of K pneumoniae on public health, especially in the food chain and health care settings.

Wound colonization with methicillin-resistant Staphylococcus aureus and hypotheses about acquisition routes in rural health care settings in Sub-Saharan Africa: Perspective from a center devoted to the treatment of cutaneous neglected tropical diseases.

We identified a high prevalence (46.4%) of wound colonization with methicillin-resistant Staphylococcus aureus (MRSA) in patients hospitalized in a center devoted to the treatment of cutaneous tropical diseases in Benin. The proportion of MRSA among S aureus isolates was 54.3%. Thirty percent of these MRSA were identified in outpatients. The analysis of pulsed-field gel electrophoresis demonstrated an important diversity of strains but also identified 8 small clusters containing between 2 and 4 isolates suggesting cross-transmission.

Residual risk of Pseudomonas aeruginosa waterborne contamination in an intensive care unit despite the presence of filters at all water points-of-use.

OBJECTIVE: To assess the residual risk of waterborne contamination by Pseudomonas aeruginosa from a water network colonized by a single genotype [sequence type (ST) 299] despite the presence of antimicrobial filters in a medical intensive care unit (ICU). METHODS: During the first 19-month period since the ICU opened, contamination of the water network was assessed monthly by collecting water upstream of the filters. Downstream water was also sampled to assess the efficiency of the filters. P. aeruginosa isolates from patients were collected and compared with the waterborne ST299 P. aeruginosa by multiplex-rep polymerase chain reaction (PCR), pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing. Cross-transmission events by other genotypes of P. aeruginosa were also assessed. RESULTS: Overall, 1.3% of 449 samples of filtered water were positive for P. aeruginosa in inoculum, varying between 1 and 104 colony-forming units/100 mL according to the tap. All P. aeruginosa hydric isolates belonged to ST299 and displayed fewer than two single nucleotide polymorphisms (SNPs). Among 278 clinical isolates from 122 patients, 10 isolates in five patients showed identical profiles to the hydric ST299 clone on both multiplex-rep PCR and PFGE, and differed by an average of fewer than five SNPs, confirming the water network reservoir as the source of contamination by P. aeruginosa for 4.09% of patients. Cross-transmission events by other genotypes of P. aeruginosa were responsible for the contamination of 1.75% of patients. DISCUSSION/CONCLUSION: Antimicrobial filters are not sufficient to protect patients from waterborne pathogens when the water network is highly contaminated. A microbiological survey of filtered water may be needed in units hosting patients at risk of P. aeruginosa infections, even when all water points-of-use are fitted with filters.

An evaluation of a Stenotrophomonas maltophilia outbreak due to commercial arterial blood gas collection kit.

BACKGROUND: Stenotrophomonas maltophilia is a gram-negative bacterium that can cause hospital infections and outbreaks within hospitals. This study aimed to evaluate an outbreak of Stenotrophomonas maltophilia, caused by ready-to-use commercial syringes containing liquid lithium and heparin for arterial blood gas collection in a university hospital. METHODS: Upon detecting an increase in Stenotrophomonas maltophilia growth in blood cultures between 15.09.2021 and 19.11.2021, an outbreak analysis and a case-control study (52 patients for the case group, 56 patients for the control group) were performed considering risk factors for bacteremia. Samples from possible foci for bacteremia were also cultured. Growing bacteria were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The genetic linkage and clonal relationship isolates were investigated with pulsed-field gel electrophoresis (PFGE) in the reference laboratory. RESULTS: In the case-control study, the odds ratio for the central venous catheter [3.38 (95% confidence interval [CI]: 1.444, 8.705 ; p = 0.006)], for surgery [3.387 (95% confidence interval [CI]: 1.370, 8.373 ; p = 0.008)] and for arterial blood gas collection history [18.584 (95% confidence interval [CI]:4.086, 84.197; p < 0.001)] were identified as significant risk factors. Stenotrophomonas maltophilia growth was found in ready-to-use commercial syringes used for arterial blood gas collection. Molecular analysis showed that the growths in the samples taken from commercial syringes and the growths from blood cultures were the same. It was decided that the epidemic occurred because the method for sterilization of heparinized liquid preparations were not suitable. After discontinuing the use of the kits with this lot number, the outbreak was brought under control. CONCLUSIONS: According to our results, disposable or sterile medical equipment should be included as a risk factor in outbreak analyses. The method by which injectors containing liquids, such as heparin, are sterilized should be reviewed. Our study also revealed the importance of the cooperation of the infection control team with the microbiology laboratory.

In vitro activity of cefiderocol against carbapenem-resistant Acinetobacter baumannii carrying various ß-lactamase encoding genes.

OBJECTIVES: This study aimed to determine the in vitro efficacy of cefiderocol in carbapenem-resistant Acinetobacter baumannii (CRAB) isolates and evaluate the disk-diffusion (DD) method as an alternative method to broth-microdilution (BMD). METHODS: Totally 89 CRAB isolates were included. Cluster analysis was determined by Pulsed-Field Gel Electrophoresis (PFGE). Resistance genes; blaOXA-51, blaOXA-23, blaOXA-24, blaOXA-58,blaPER-1, blaNDM, blaIMP and mcr-1 were screened. Cefiderocol susceptibility testing was performed by both DD and BMD. Interpretation was made according to EUCAST and CLSI. Categorical agreement (CA), minor errors (mEs), major errors (MEs), and very major errors (VMEs) were determined. RESULTS: PFGE revealed 5 distinct pulsotypes; 86 of the isolates were extensively drug-resistant (XDR). All the isolates were negative for blaNDM, blaIMP, mcr-1, while positive for blaOXA-58 and blaOXA51. blaPER-1 was positive for 33.7%; blaOXA-23 for 74.2%; blaOXA-24 for 12.3%. According to CLSI, the MEs rate was 1.85%, mEs was 7.86% and there were no VMEs. According to EUCAST, MEs rate was 3.70%, there were no mEs and VMEs. CA was 91% for CLSI and 97.8% for EUCAST. MICs of cefiderocol against A. baumannii isolates ranged from 0.06 to > 128 mg/L, with MIC50 and MIC90 values of 0.5 and > 128 mg/L, respectively. CONCLUSIONS: Cefiderocol susceptibility was 60.7% in CRAB isolates. MIC50, MIC90 of blaPER-1 positive and blaPER-1 negative groups were > 128/>128 and 0.25/>128 mg/L. A correlation between the presence of blaPER-1 and cefiderocol resistance was observed (p < 0.0001). Among colistin-resistant isolates, the presence of blaPER-1 was 47.1% and 75% of them were resistant to cefiderocol respectively.

Antibiotic-Resistance Profiles and Genetic Diversity of Shigella Isolates in China: Implications for Control Strategies.

The urgent need for comprehensive and systematic analyses of Shigella as the key pathogen led us to meticulously explore the epidemiology and molecular attributes of Shigella isolates. Accordingly, we procured 24 isolates (10 from Xinjiang and 14 from Wuhan, China) and performed serotype identification and antimicrobial susceptibility testing. Resistance gene detection and homology analysis by polymerase chain reaction and pulsed-field gel electrophoresis (PFGE), respectively, were performed for genetic diversity analysis. All isolates were identified as Shigella flexneri, with 70% (35.4-91.9%) and 30% (8.1-64.6%) of the Xinjiang isolates and 85.7% (56.2-97.5%) and 14.3% (2/14, 2.5-43.9%) of the Wuhan isolates belonging to serotype 2a and serotype 2b, respectively. All isolates displayed resistance to at least two antibiotics and complete resistance to ampicillin. Multidrug resistance (MDR) was recorded in 70.8% (48.8-86.6%) of isolates, with Xinjiang isolates exhibiting relatively higher resistance to ampicillin-sulbactam, piperacillin, ceftriaxone, and aztreonam. Conversely, Wuhan isolates displayed higher MDR and resistance to tetracycline, ciprofloxacin, levofloxacin, and cefepime relative to Xinjiang isolates. Molecular scrutiny of antibiotic-resistance determinants revealed that blaTEM was the main mechanism of ampicillin resistance, blaCTX-M was the main gene for resistance to third- and fourth-generation cephalosporins, and tetB was the predominant gene associated with tetracycline resistance. Four Xinjiang and seven Wuhan isolates shared T1-clone types (>85%), and two Xinjiang and one Wuhan isolates were derived from the T6 clone with a high similarity of 87%. Six PFGE patterns (T1, T2, T5, T6-3, T8, and T10) of S. flexneri were associated with MDR. Thus, there is a critical need for robust surveillance and control strategies in managing Shigella infections, along with the development of targeted interventions and antimicrobial stewardship programs tailored to the distinct characteristics of Shigella isolates in different regions of China.

Molecular characterization of Escherichia coli isolates recovered from broilers with cellulitis.

Avian cellulitis in broilers, caused by avian pathogenic Escherichia coli, is a major cause for carcass rejections during meat inspection, resulting in significant economic losses. In this study, we analysed E. coli isolates obtained from broiler chickens affected by cellulitis for their genetic relatedness and antimicrobial resistance phenotype and genotype. The objective was to determine whether there is a clonal spread or whether these clinical isolates differ. For this purpose, E. coli was isolated from swab samples collected from diseased broilers across 77 poultry farms in Germany, resulting in 107 isolates. These isolates were subjected to serotyping, PCR-based phylotyping and macrorestriction analysis with subsequent pulsed-field gel-electrophoresis for typing purposes. In addition, the presence of virulence genes associated with avian pathogenic E. coli (APEC) was investigated by PCR. Antimicrobial susceptibility of the isolates was examined by the disk diffusion method according to CLSI guidelines and subsequently, the presence of corresponding resistance genes was investigated by PCR. Typing results revealed that a significant proportion of the isolates belonged to serotype O78:K80, which is one of the major APEC serotypes. Phylogenetic grouping showed that phylogenetic group D was most commonly represented (n = 49). Macrorestriction analysis showed overall heterogenous results, however, some clustering of closely related isolates was observed. The level of antimicrobial resistance was high, with 83.8% of isolates non-susceptible to at least one class of antimicrobial agents and 40% of isolates showing resistance to at least three classes. The most frequently observed resistance was to ampicillin, mediated by blaTEM (n = 56). However, few isolates were non-susceptible to ciprofloxacin (n = 8) and none of the isolates was resistant to 3rd generation cephalosporins or carbapenems. Overall, the results show that genetically diverse APEC associated with avian cellulitis can be found among and within German poultry farms. While most isolates were antimicrobial resistant, resistance levels to high(est) priority critically important antimicrobials were low.