PDF(Pubmed)
Abstract：
Actinotignum schaalii is an underrecognized Gram-positive bacillus that is associated with urinary tract infections and cutaneous abscesses. The role of A. schaalii in invasive infections continues to be unappreciated because the bacteria can be isolated from a diverse spectrum of clinical specimens, ranging from being a single pathogen in urine and blood cultures to being deemed a colonizer in polymicrobial anaerobic cultures of sterile fluids and tissues. We conducted a microbiological analysis of clinical isolates obtained from 2012 through 2019. A total of 86 isolates were analyzed; 37 (43%) were from blood cultures, 35 (41%) were from deep wounds and abscesses, 6 (7%) were from urine samples, and the rest were recovered from peritoneal, kidney, and scrotal fluid samples. Urinary tract infections were clinically identified as the source of most cases of bacteremia, although no simultaneous urine cultures yielded positive results. The 16S rRNA gene sequences were available for 32 isolates (37%). Phylogenetic analysis revealed that AS.1/AS.2 strains caused a larger proportion of bloodstream infections (BSIs) (100% versus 52% [P = 0.01]) and trended toward a higher rate of hospitalization (91% versus 76% [P = 0.18]) but had a lower clindamycin MIC90 (0.12 versus >256 μg/mL). Our study emphasizes the emergence of A. schaalii as a pathogen in human urine samples, BSIs, and skin and soft tissue infections. It highlights the pitfalls of current laboratory methods in recovering and identifying this organism from clinical specimens, particularly urine samples. Phylogenetic analysis showed unique genotypic sequences for A. schaalii AS.1/AS.2 strains causing urosepsis, which requires further study to identify potential virulence factors. IMPORTANCE Actinotignum schaalii is an underrecognized Gram-positive bacillus due to its special growth requirements and prior phenotypic identification methods, and it is often mistaken as a contaminant. It has been associated with various clinical syndromes, from urinary tract infections to cutaneous infections. The widespread use of molecular diagnostic methods allowed for improved detection. However, its role in invasive infections remains underappreciated. We conducted a detailed microbiological analysis to improve our understanding of this organism\'s genotypic and phenotypic characteristics. Our results highlight the pitfalls of clinical laboratory recovery, particularly from urine cultures. Although most BSIs were caused by urinary tract infections, no simultaneous urine cultures identified A. schaalii, largely due to the failure of phenotypic methods to reliably isolate and identify this organism. Additionally, this is the first study demonstrating A. schaalii strains with differences in clinical and microbiological characteristics, raising the possibility of potential bacterial virulence factors contributing to invasive infections.
摘要：
沙氏放线菌是一种未被认可的革兰氏阳性杆菌，与尿路感染和皮肤脓肿有关。沙氏芽孢杆菌在侵袭性感染中的作用仍然没有得到重视，因为这种细菌可以从不同的临床标本中分离出来。从尿液和血液培养物中的单一病原体到无菌液体和组织的多微生物厌氧培养物中的定植者。我们对2012年至2019年获得的临床分离株进行了微生物学分析。总共分析了86个分离株；37个（43％）来自血液培养物，35人（41%）来自深层伤口和脓肿，6（7%）来自尿液样本，其余的从腹膜中恢复,肾,和阴囊液样本.临床上确定尿路感染是大多数菌血症的来源，尽管没有同时尿液培养产生阳性结果。16SrRNA基因序列可用于32个分离株(37%)。系统发育分析显示，AS.1/AS.2菌株引起的血流感染（BSIs）比例更高（100％对52％[P=0.01]），住院率更高（91％对76％[P=0.18]），但克林霉素90较低（0.12对>256μg/mL）。我们的研究强调了沙氏芽孢杆菌作为人类尿液样本中病原体的出现，BSIs,皮肤和软组织感染.它强调了当前实验室方法在从临床标本中恢复和识别这种生物的陷阱，尤其是尿液样本。系统发育分析显示导致尿脓毒血症的沙氏A.schaaliiAS.1/AS.2菌株的独特基因型序列，这需要进一步研究以确定潜在的毒力因子。IMPORTANCESchaaliiActinotignumschaalii是一种未被认可的革兰氏阳性芽孢杆菌，由于其特殊的生长要求和先前的表型鉴定方法，它经常被误认为是污染物。它与各种临床综合征有关，从尿路感染到皮肤感染。分子诊断方法的广泛使用允许改进的检测。然而,其在侵袭性感染中的作用仍未得到充分重视。我们进行了详细的微生物学分析，以提高我们对这种生物的基因型和表型特征的理解。我们的结果突出了临床实验室恢复的陷阱，特别是从尿液培养。虽然大多数BSI是由尿路感染引起的，没有同时尿液培养物鉴定出沙卡利，主要是由于表型方法无法可靠地分离和鉴定这种生物。此外,这是第一项证明沙氏芽孢杆菌菌株在临床和微生物学特征上存在差异的研究，提高潜在细菌毒力因子导致侵袭性感染的可能性。
