Secondary Mycobacterium abscessus Infection after Debridement in Child with Dog Bite: a Case Report.

BACKGROUND: In recent years, there have been increasing reports related to infection caused by Mycobacterium abscessus (MAB). As one of the most common mycobacterium iatrogenic infections, it is characterized by pulmonary infection. However, only a few reports of MAB-related skin and soft tissue infections are available. This study reported a 3-year-old child admitted to our hospital for a dog bite with MAB infection after debridement. METHODS: The diagnosis of MAB in this child was made after detecting the bacteria in the wound secretion based on secretion culture in clinical laboratory. RESULTS: The result of the first bacterial isolation and culture of wound secretion was negative. However, the results were positive two days later and was diagnosed as MAB infection for samples of the purulent secretions collected by puncture and aspiration during debridement from the red and swollen regions of the thigh. The drug sensitivity results suggested that the child was sensitive to cefoxitin. However, she was resistant to amikacin, linezolid, minocycline, imipenem, tobramycin, moxifloxacin, clarithromycin, and doxycycline. The combined treatment strategy was used for managing MAB infection with a good effect. CONCLUSIONS: The management of MAB soft tissue infection has limitations, like poor tolerance, toxicity, and mul¬ti-drug interaction. The combined treatment strategy is important for MAB infection, and monitoring adverse re-actions and toxicity is the key.

[Relationship Between the VNTR Loci Polymorphism and MALDI-TOF MS Protein Profile Diversity in Mycobacterium tuberculosis Complex].

OBJECTIVE: To study the relationship between the copy numbers of repetitive units at variable number tandem repeat (VNTR) loci of Mycobacterium tuberculosis complex (MTBC) with its diversity of protein profiles. METHODS: The MTBC strains were subjected to genotyping using multiple locus variable number tandem repeat analysis (MLVA). Also, the principal component analysis (PCA) was performed for bacterial protein profiles of MTBC using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The relationship between the polymorphism of VNTR loci and PCA clustering was analyzed. RESULTS: A total of 157 MTBC strains were collected. 146 MTBC strains (MS identification score values ≥1.700) were performed PCA and three clusters, clusterⅠ(61 strains), clusterⅡ(26 strains) and cluster Ⅲ(59 strains), were generated. Polymorphic diversities were observed in 24 VNTR loci, among them, 7 were highly various, 7 were moderately, and 10 were low various. The polymorphism of Mtub39, QUB26 and QUB4156 loci were correlated with the results of MALDI-TOF MS clustering (P=0.000, P=0.035, P=0.017). CONCLUSION: The polymorphism of Mtub39, QUB26 and QUB4156 loci in MTBC was correlated with the difference of MALDI-TOF MS protein profiles, suggesting that these loci may play a role in regulating the composition of protein profiles of MTBC strains.

[Galactomannan Tests of Bronchoalveolar Lavage Fluid for Diagnosing Invasive Pulmonary Aspergillosis].

OBJECTIVE: To determine the value of galactomannan (GM) in bronchoalveolar lavage fluid (BALF) for diagnosing invasive pulmonary aspergillosis. METHODS: According to the European Organization for Research and Treatment of Cancer / Invasive Fungal Infection Group (EORTC / IFICG) and the American Mycosis Research Group (MSG),and the American College of Infectious Diseases (IDSA) guidelines,295 patients with pulmonary aspergillosis (IPA) and high risk of invasive infections were divided into four groups: IPA group (42 cases),clinically diagnosed group (68 cases),suspected group (61 cases),and non-IPA group (124 cases). Their serum and BALF concentrations of GM were detected by enzyme-linked immunosorbent assay (ELISA).The clinically diagnosed and confirmed invasive pulmonary fungal infections (IPFI) were treated as golden standards (+). A GM value ≥ proposed threshold was deemed diagnostic test positive. Receiver operating characteristic (ROC) curves were drawn to determine the diagnostic efficiency of BALF GM assay for IPFI. The optimal cut-off point of BALF GM was determined using Youden index. RESULTS: BALF GM had an area under the curve (AUC) of 0.932 in diagnosing IPFI,with 87.5% sensitivity, 96.7% specificity, 87.5% positive predictive value,and 96.7% negative predictive value when the BALF GM value was set at 1.5 ng/mL as the optimal cut-off point. Higher BALF and serum GM values were found in the confirmed IPA group,followed by the clinical diagnosed group compared with the non-IPA group ( P<0.05). The threshold value was set at 0.5 ng/mL for serum GM and 1.5 ng/mL for bronchoalveolar lavage GM. Higher positive rates were found in the confirmed IPA group and the clinical diagnosed group compared with the non-IPA group ( P<0.05). Serum GM appeared to have higher false positives and false negative rates. CONCLUSION: BALF GM is a rapid and accurate indicator with high sensitivity and specificity for the early diagnosis of IPA.