Molecular epidemiology and risk factors of Stenotrophomonas maltophilia infections in a Chinese teaching hospital

Abstract

Background: Stenotrophomonas maltophilia (S. maltophilia) is an important opportunistic pathogen that can be isolated in hospitals. With the abuse of broad spectrum antibiotics and invasive surgical devices, the rate of S. maltophilia infection is increasing every year. This study is an epidemiological analysis of the clinical and molecular characteristics of S. maltophilia infection in a Chinese teaching hospital. The goal is to obtain a comprehensive understanding of the status of S. maltophilia infection in order to provide strong epidemiological data for the prevention and treatment of S. maltophilia infection.Results: A total of 93 isolates from Renji Hospital affiliated to Shanghai Jiaotong University School of Medicine were included, in which 62 isolates were from male patients and 81 isolates were isolated from sputum samples. A total of 86 patients had underlying diseases. All of the patients had received antibiotic therapeutics. The multilocus sequence typing (MLST) analysis indicated that 61 different sequence types (STs) were found (including 45 novel STs), and the MLST did not show significantly dominant STs. Pulsed field gel electrophoresis (PFGE) results showed the 93 isolates could be divided into 73 clusters, and they also showed weak genetic linkage between isolates. The resistant rates to Trimethoprim/sulfamethoxazole (TMP/SMX) and levofloxacin were 9.7% and 4.3%, respectively, and all of the isolates were susceptible to minocycline. The positive rates of the four virulence genes Stmpr1, Stmpr2, Smf-1, and Smlt3773 locus were 79.6%, 91.4%, 94.6%, and 52.7%, respectively. The positive rates of the three biofilm genes rmlA, spgM, and rpfF were 82.8%, 92.5%, and 64.5%, respectively. The mean biofilm forming level of OD492 was 0.54 ± 0.49, and there was no significant difference between different genders and different age groups. Data from patients in the intensive care unit (ICU) and the control group were analyzed retrospectively, and the independent risk factors of those who were infected in the ICU included immunosuppression and the increased of the antibiotics usage.Conclusions: Most of the patients had prior medical usage histories and baseline diseases. The positive rate of virulence genes was high, the drug resistance rate of S. maltophilia was low, and the biofilm formation ability was strong. The increased use of antibiotics was an independent risk factor for S. maltophilia infection, which should receive more attention. No obvious clonal transmission was found in the same department.

Impact of COVID-19 on the Distribution of Pathogenic Bacteria in the Lower Respiratory Tract of the Elderly

“…According to one study, individuals over the age of 60 were more prone to S. maltophilia infection, which could be attributed to immunosuppression [11] . In recent years, S. maltophilia has been relatively stable in third place among non-fermenting Gram-negative bacteria, after Pseudomonas aeruginosa and Acinetobacter baumannii, according to the CHINET monitoring service [12] . Patients with severely impaired or weakened immune functions were more susceptible to serious consequences when infected with S. maltophilia, suggesting that the respiratory tract was the main site of colonization and infection ofS.…”