Purpose
In the lungs of cystic fibrosis patients, Pseudomonas aeruginosa is exposed to a myriad of antibiotics leading to alterations in antibiotic susceptibility. This study identifies mutations ...resulting in hypersusceptibility in isogenic mutants of a P. aeruginosa clinical isolate, PA34.
Methods
PA34 was exposed to subinhibitory concentrations of doripenem or meropenem during growth to mid‐log phase. Antibiotic susceptibility of surviving colonies was determined by agar dilution. Two carbapenem‐resistant colonies hypersusceptible to non‐carbapenem antibiotics were selected for further analysis. Antibiotic resistance gene expression was evaluated by RT‐rtPCR and OprD production by SDS‐PAGE. PA34 and isogenic mutants were evaluated with whole genome sequencing. Sequence variants were confirmed by Sanger sequencing, and cognate genes in eight carbapenem‐resistant clinical isolates hypersusceptible to non‐carbapenem antibiotics were sequenced. Lipopolysaccharide preparations of PA34 and hypersusceptible mutants were evaluated with ProQ‐Emerald stain.
Results
Isogenic mutants showed 4‐ to 8‐fold MIC increase for imipenem, meropenem, and doripenem. However, they were hypersusceptible (≥4‐fold MIC decrease) to aminoglycosides, fluoroquinolones, and non‐carbapenem β‐lactams. Expression of ampC or mex‐opr efflux pumps was unchanged, but OprD production was decreased. Mutations causing Q86H AlgU and G77C LptG amino acid substitutions and nonsense mutations within OprD were observed in both mutants. Lipopolysaccharide modifications were observed between isogenic mutants and PA34. Non‐synonymous mutations in LptF or LptG were observed in 6/8 hypersusceptible clinical isolates resistant to carbapenem antibiotics.
Conclusion
Evaluation of hypersusceptible mutants identified the association between lptG and a hypersusceptible phenotype. Modifications in lipopolysaccharide profiles suggests LptG modification interferes with lipopolysaccharide transport and contributes to hypersusceptibility.
This study identifies mutations resulting in hypersusceptibility in isogenic mutants and clinical isolates of Pseudomonas aeruginosa. Mutations in the gene encoding the LptG subunit of the LptFG heterodimer were found to alter lipopolysaccharide (LPS) profiles in isogenic mutants. Modifications in LPS profiles suggest LptG modification interferes with LPS transport and contributes to hypersusceptibility.
•Chryseobacterium gleum is ubiquitously distributed in the environment.•It can cause pneumonia in patients with underlying disease such as nephrotic syndrome especially with medical device use.•The ...treatment of Chryseobacterium is challenging; the patient we presented was treated with levofloxacin.
Chryseobacterium gleum is commonly distributed in the environment. It can cause a wide variety of infections in immunocompromised patients in hospital setting.
A 6 month old infant with nephrotic syndrome was admitted to the emergency room for an acute onset of fever, difficulty breathing, cyanosis, and low oral intake. Cultures of endotracheal tube specimens were positive for Chryseobacterium gleum which was confirmed by ribosomal sequencing. The organism was susceptible to trimethoprim-sulfamethoxazole, minocycline, and levofloxacin. The patient clinically improved on levofloxacin treatment.
To the best of our knowledge, this is the first case of pneumonia caused by Chryseobacterium gleum in an infant with nephrotic syndrome. It is also the first report of C. gleum causing respiratory tract infection in Saudi Arabia.
The recent incorporation of bacterial whole-genome sequencing (WGS) into Public Health laboratories has enhanced foodborne outbreak detection and source attribution. As a result, large volumes of ...publicly available datasets can be used to study the biology of foodborne pathogen populations at an unprecedented scale. To demonstrate the application of a heuristic and agnostic hierarchical population structure guided pan-genome enrichment analysis (PANGEA), we used populations of
S. enterica
lineage I to achieve two main objectives: (i) show how hierarchical population inquiry at different scales of resolution can enhance ecological and epidemiological inquiries; and (ii) identify population-specific inferable traits that could provide selective advantages in food production environments. Publicly available WGS data were obtained from NCBI database for three serovars of
Salmonella enterica
subsp.
enterica
lineage I (
S
. Typhimurium,
S
. Newport, and
S
. Infantis). Using the hierarchical genotypic classifications (Serovar, BAPS1, ST, cgMLST), datasets from each of the three serovars showed varying degrees of clonal structuring. When the accessory genome (PANGEA) was mapped onto these hierarchical structures, accessory loci could be linked with specific genotypes. A large heavy-metal resistance mobile element was found in the Monophasic ST34 lineage of
S
. Typhimurium, and laboratory testing showed that Monophasic isolates have on average a higher degree of copper resistance than the Biphasic ones. In
S
. Newport, an extra
sugE
gene copy was found among most isolates of the ST45 lineage, and laboratory testing of multiple isolates confirmed that isolates of
S
. Newport ST45 were on average less sensitive to the disinfectant cetylpyridimium chloride than non-ST45 isolates. Lastly, data-mining of the accessory genomic content of
S
. Infantis revealed two cryptic Ecotypes with distinct accessory genomic content and distinct ecological patterns. Poultry appears to be the major reservoir for Ecotype 1, and temporal analysis further suggested a recent ecological succession, with Ecotype 2 apparently being displaced by Ecotype 1. Altogether, the use of a heuristic hierarchical-based population structure analysis that includes bacterial pan-genomes (core and accessory genomes) can (1) improve genomic resolution for mapping populations and accessing epidemiological patterns; and (2) define lineage-specific informative loci that may be associated with survival in the food chain.
can cause the zoonotic disease tularemia and is partitioned into subspecies due to differences in chromosomal organization and virulence. The subspecies
(type B) is generally considered more clonal ...than the other subpopulations with moderate virulence compared to the hypervirulent A.I clade. We performed whole genome sequencing (WGS) on six type B strains isolated from the blood of patients with tularemia within a one-year period from the same United States region, to better understand the associated pathogenicity. The WGS data were compared to the prototype strain for this subspecies, specifically FSC200, which was isolated from a patient with tularemia in Europe. These findings revealed 520-528 single nucleotide polymorphisms (SNPs) between the six United States type B strains compared to FSC200, with slightly higher A+T content in the latter strain. In contrast, comparisons between the six type B isolates showed that five of the six type B isolates had only 4-22 SNPs, while one of the strains had 47-53 SNPs. Analysis of SNPs in the core genome for the six United States type B isolates and the FSC200 strain gave similar results, suggesting that some of these mutations may have been nonsynonymous, resulting in altered protein function and pathogenicity.
To detect resistance genes to fluoroquinolones and β-lactams in Salmonella strains from a Saudi hospital.
From October 2015 to December 2016, a total of 149 Salmonella strains were collected from ...stool specimens from patients admitted to King Fahad Hospital of the University, AlKhobar, Saudi Arabia using CHROMagar Salmonella. The organism identification and antimicrobial susceptibility testing were performed using Vitek 2 system. Strain serogrouping was performed using Wellcolex color Salmonella kit. Fluoroquinolone resistance genes, extended-spectrum β-lactamases (ESBLs), and AmpC β-lactamase were determined using polymerase chain reaction (PCR). Enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR) was used to determine clonal relatedness.
The resistance rates to cefotaxime were 1.3% and ciprofloxacin 19.5%. Plasmid mediated quinolone resistance (PMQR) genes, qnrB and qnrS, were detected in 8 strains, qnrB (n=5) and qnrS (n=3), respectively. No ESBLs, AmpC, or mutations in the topoisomerases were detected. Salmonella isolates formed 7 clusters with similarity.
This study reveals the emergence of fluoroquinolone resistant Salmonella in the region imposing public health concerns.
The aim of this study was to determine the prevalence of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Proteus mirabilis (P. ...mirabilis). In addition, different methods for detection of these enzymes, including the newly introduced CHROMagar ESBL, were evaluated.
A total of 382 Enterobacteriaceae clinical isolates were obtained from King Fahad Specialist Hospital - Dammam, during 2011 and screened for production of ESBL using advanced expert system of Vitek 2, CHROMagar and ESBL-E-strips. PCR assay was used to detect blaTEM, blaSHV, and blaCTX-M genes. Susceptibility to a panel of antibiotics was determined.
The overall proportion of ESBL-producing enterobacterial isolates was 30.6%, which was higher in E. coli (35.8%) than in K. pneumoniae (25.7%). ESBL genotypes showed remarkable increase in the CTX-M (97.4%) compared to SHV (23.1%). The predominant ESBL was CTX-M- 15 (92.1 %). No TEM ESBL was detected in this study. The Vitek2 showed the highest sensitivity (100%), and the CHROMagar had the lowest specificity (97.3%) compared to the molecular method. All isolates were susceptible to imipenem and meropenem.
This study confirms a high level of blaCTX-M positive ESBL isolates are circulating in the Eastern Province of Saudi Arabia. The trend of a multidrug-resistant profile associated with the recovery of the blaCTX-M gene is alarming.
Understanding the significance of cytopathological tests in evaluating various infectious processes have become very essential nowadays, as it is a safe, fast, and cost-effective procedure. We ...present a case of a 52-year-old male with Salmonella empyema where the causative organisms were initially identified on cytology, and subsequently confirmed by microbiological culture. Diff-Quik stained smears showed many colorless, slender, fat short bacilli, which were visualized against the blue-gray background of the smear. These bacilli were identified both intracellularly inside the histiocytes and neutrophils cytoplasm as well as extracellularly in the smear background. We consider that this negative image represents the organism and its capsule creating an area that did not take the Diff-Quik stain. The patient was treated accordingly with suitable antibiotics. A brief discussion of this interesting finding in such a rare infection with pertinent literature review is presented.
A cost analysis of combining a tuberculin skin test (TST) and the QuantiFERON-TB Gold test (QFT-GT) to detect latent tuberculosis in newly hired health care workers was performed. An approximately ...50% reduction in the cost of additional care was realized when workers with positive TST results were subsequently screened using the QFT-GT.
First report of Candida auris infections from Saudi Arabia Abdalhamid, Baha; Almaghrabi, Reem; Althawadi, Sahar ...
Journal of infection and public health,
July-August 2018, 2018 Jul - Aug, 2018-07-00, Letnik:
11, Številka:
4
Journal Article
PDF
