The study investigated A. baumannii
infections with three kinds of clinical characters: Antibiotic resistance, cross-infection, and inducible resistance. Among the microbial infections, MDRAB is one of the most severe nosocomial pathogens and causes cross-infections in hospitals. Tien et al
] reported that infections in the injured soldiers contracted while in the military field hospitals were caused by A. baumannii
. These isolations were resistant to numerous classes of antimicrobials, including the carbapenems. Previous studies have also reported nosocomial infections caused by A. baumannii
, in neurosurgery and neonatal ICUs.[23
] In addition, antibiotic-resistant bacterial nosocomial infections were also the main pathogen in ICU. Most bacterial infections, such as A. baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus
, and Streptococcus pyogenes
, were isolated from ICU. Among the isolations, A. baumannii
was more resistant to a larger numbers of antibiotics.[25
] For example, A. baumannii
was associated with urinary tract infections, respiratory tract infections, septicemia, bacteremia, meningitis, and wound infections.
IL-1 was among the pro-inflammatory cytokines that contributed to the inflammation and immune response. Activated monocytes and macrophages, as well as T and B cells and NK cells, secrete IL-1, which can affect the activation of T cells and the differentiation of B cells. The IL-1 family consists of IL-1 alpha (IL-1α), IL-1 beta (IL-1β), and IL-1ra. Both IL-1α and IL-1β were the most potent pro-inflammatory cytokines, and they bonded to the IL-1 receptor (IL-1R) on the cell surface. This way, they were able to initiate a cascade of signal transduction to affect the activation of macrophages and neutrophils. In contrast, IL-1ra also bonded to the IL-1R, but the IL-1ra was a competitive inhibitor that attenuated a signal transduction. Romero and Tartakovsky[26
] reported that pretreatment with IL-1ra could prevent the pre-term parturition induced by IL-1 in mice experiments. Lynch et al
] found that the expression was fundamentally different between women and men, with the IL-1ra levels in women being higher. And, the result was also found that IL-1ra might inhibit IL-1 activity or up regulate IL-1 gene expression. McIntyre et al
] reported that the initiation and termination of the pro-inflammatory response could be mediated by the relative concentrations of IL-1β and IL-1ra.
Tarlow et al
] reported that the polymorphic site of the IL-1ra gene's intron 2 contains three protein-binding sites: An α-interferon silencer A, a β-interferon silencer A, and an acute-phase response element. These sites, with potential regulating effects, might affect the production of the interleukin-1 family system. In coding or non-coding regions of the IL-1ra gene, there might be either a single-base pair substitution of one nucleotide for another or a variable nucleotide of repeats of a short, repetitive DNA sequence. These variations may influence the rate of gene transcription, the stability of the messenger RNA, or the quantity and activity of the resulting protein. Thus, the possession of specific alleles of polymorphic genes would influence the susceptibility to or severity of a number of disorders.[16
This work studied the distribution of the 86-bp VNTR in the IL-1ra gene's intron 2. The frequencies of the IL-1ra genotype were associated with the occurrence of MDRAB-related pneumonia in the hospital. Furthermore, the results showed that the frequency of allele 1 in IL-1ra polymorphism in MDRAB-related pneumonia cases was significantly higher than in the control group. This was the first study to investigate the association between IL-1ra polymorphism and MDRAB-related pneumonia. The results revealed that IL-1ra polymorphism might be associated with the risk of MDRAB-related pneumonia. Our study had some limitations, such as the small size of the group and the ethnic differences among its subjects, but the difference was statistically significant. In conclusion, we suggest that IL-1ra polymorphism is associated with patients who have MDRAB-related pneumonia.