Dataset Information

Molecular characteristics of antibiotic-resistant Escherichia coli and Klebsiella pneumoniae strains isolated from hospitalized patients in Tehran, Iran.

ABSTRACT:

Background

We evaluated the distribution of carbapenem and colistin resistance mechanisms of clinical E. coli and K. pneumoniae isolates from Iran.

Methods

165 non-duplicate non-consecutive isolates of K. pneumoniae and E. coli were collected from hospitalized patients admitted to Iran's tertiary care hospitals from September 2016 to August 2018. The isolates were cultured from different clinical specimens, including wound, urine, blood, and tracheal aspirates. Antibiotic susceptibility testing was performed by disc diffusion and microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) guideline. The presence of extended spectrum β-lactamases (ESBLs) genes, carbapenemase genes, as well as fosfomycin resistance genes, and colistin resistance genes was also examined by PCR-sequencing. The ability of biofilm formation was assessed with crystal violet staining method. The expression of colistin resistance genes were measured by quantitative reverse transcription-PCR (RT-qPCR) analysis to evaluate the association between gene upregulation and colistin resistance. Genotyping was performed using the multi-locus sequencing typing (MLST).

Results

Colistin and tigecycline were the most effective antimicrobial agents with 90.3% and 82.4% susceptibility. Notably, 16 (9.7%) isolates showed resistance to colistin. Overall, 33 (20%), 31 (18.8%), and 95 (57.6%) isolates were categorized as strong, moderate, and weak biofilm-producer, respectively. Additionally, bla_TEM, bla_SHV, bla_CTX-M, bla_NDM-1, bla_OXA-48-like and bla_NDM-6 resistance genes were detected in 98 (59.4%), 54 (32.7%), 77 (46.7%), 3 (1.8%), 17 (10.30%) and 3 (1.8%) isolates, respectively. Inactivation of mgrB gene due to nonsense mutations and insertion of IS elements was observed in 6 colistin resistant isolates. Colistin resistance was found to be linked to upregulation of pmrA-C, pmrK, phoP, and phoQ genes. Three of bla_NDM-1 and 3 of bla_NDM-6 variants were found to be carried by IncL/M and IncF plasmid, respectively. MLST revealed that bla_NDM positive isolates were clonally related and belonged to three distinct clonal complexes, including ST147, ST15 and ST3299.

Conclusions

The large-scale surveillance and effective infection control measures are also urgently needed to prevent the outbreak of diverse carbapenem- and colistin-resistant isolates in the future.

SUBMITTER: Sharahi JY

PROVIDER: S-EPMC8077724 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Introduction:Klebsiella pneumoniae is one of the most important infectious agents in neonates. There are "classic" and hypervirulent strains of K. pneumoniae. The "classic" non-virulent strain of K. pneumoniae, producing extended-spectrum beta-lactamases (ESBLs), is associated with nosocomial infections. Hypervirulent K. pneumoniae strains are associated with invasive infections in previously healthy adult people, and most of them exhibit antimicrobial susceptibility. The role of virulent strains of K. pneumoniae (including hv-KP) in neonatal infections is unknown. The aim of the study was the assessment of the impact of virulence factors and antibiotic resistance of K. pneumoniae strains on clinical features and outcomes of neonatal infection. Materials and Methods: Two groups of infants were enrolled. The first group consisted of 10 neonates with sepsis caused by K. pneumoniae. The second group consisted of 10 neonates with urinary tract infection (UTI) caused by K. pneumoniae. We investigated the susceptibility of K. pneumoniae isolates to antibiotics, the ability of the microorganism to produce ESBL, and virulence factors, including the rmpA gene, aerobactin, and colibactin genes. In neonates with sepsis, we investigated K. pneumoniae isolates, which was taken from the blood, in neonates with UTI-from the urine. Results: In neonates with sepsis testing of K. pneumoniae isolates for ESBL production was positive in 60% of cases, in neonates with UTI-in 40% of cases. All blood and urine ESBL producing K. pneumoniae isolates were resistant to ampicillins, including protected ones, and third-generation cephalosporins. At the same time, these isolates were sensitive to meropenem, amikacin, and ciprofloxacin. The rmpA gene was detected in four blood, and three urine K. pneumoniae isolates. In neonates with sepsis rmpA gene in two cases was detected in ESBL-producing K. pneumoniae isolates. They were infants with meningitis, and both cases were fatal. In the group of infants with UTI, the rmpA gene was detected only in K. pneumoniae isolates not producing ESBL. Aerobactin and colibactin genes were detected in two neonates with sepsis and in three neonates with UTI. In all cases, aerobactin and colibactin genes were detected only in rmpA-positive K. pneumoniae isolates. Out of three fatal outcomes, two cases were caused by hv-KP producing ESBL. Conclusion: The prevalence of virulent strains of K. pneumoniae among neonates with sepsis and other neonatal infection is higher than we think. The most severe forms of neonatal sepsis with an unfavorable outcome in our study were due to virulent strains of K. pneumoniae.