Infection and Drug Resistance最新文献

Purpose: To present a rare case of pulmonary cryptococcosis that exhibited radiological findings consistent with interstitial pneumonia in a patient diagnosed with IgA (Immunoglobulin A) nephropathy.

Patients and methods: A 66-year-old man was admitted to the hospital with interstitial lung disease. The cryptococcal capsular antigen test was positive in both serum and bronchoalveolar lavage fluid. Histopathological examination of the bronchoscopically obtained lung biopsy and positive culture results revealed the presence of Cryptococcus yeast, while no Cryptococcus species were detected in the cerebrospinal fluid. Collectively, these findings confirmed the diagnosis of pulmonary cryptococcosis.

Results: The fluconazole dosage was tailored according to the patient's renal function, and the lesions in the right lung were significantly improved following one month of antifungal therapy.

Conclusion: This case illustrates that in immunocompromised patients, pulmonary cryptococcosis may manifest with imaging findings resembling interstitial pneumonia. Therefore, clinicians should consider pulmonary cryptococcosis in the differential diagnosis of interstitial pneumonia, particularly in immunocompromised individuals.

Purpose: Epidemiological data on small colony variants (SCVs) of Staphylococcus aureus (S. aureus) in China are lacking. This study aimed to investigate the prevalence and characteristics of S. aureus SCVs in patients with Pseudomonas aeruginosa (P. aeruginosa) pneumonia.

Methods: From October 2024 to September 2025, S. aureus SCVs were collected from lower respiratory tract specimens at two tertiary hospitals in Fuzhou and identified using MALDI-TOF MS. Antibiotic susceptibility testing was performed using a VITEK ^® 2 Compact System. Genetic diversity and virulence were analyzed using multilocus sequence typing (MLST), staphylococcal protein A (spa) typing, and toxin gene profiling. Biofilm formation was assessed using a microtiter plate assay, and patient characteristics were analyzed using the Hospital Information System.

Results: Thirty-eight S. aureus SCVs (2.1%) were isolated from 1,832 lower respiratory tract specimens collected from patients with P. aeruginosa pneumonia. Compared to normal phenotype strains, SCVs exhibited smaller colonies and reduced hemolysis. Among resistant strains, 20 were methicillin-resistant S. aureus SCVs (MRSA-SCVs), with ST1-t128 (25.0%) being the most prevalent. ST764-t1084 MRSA-SCVs were resistant to penicillin, oxacillin, gentamicin, ciprofloxacin, levofloxacin, moxifloxacin, erythromycin, clindamycin, and tetracycline. Eighteen strains were methicillin-susceptible S. aureus SCVs (MSSA-SCVs), predominantly ST72-t3735 (16.7%). Virulence analysis showed adhesion-related gene carriage rates of 47.4-100.0% and immune evasion gene carriage rates of 52.6-73.7%. In addition, most S. aureus SCVs showed strong biofilm production.

Conclusion: This study identified a 2.1% prevalence of S. aureus SCVs (often undetected) in P. aeruginosa pneumonia patients. More than half of patients were methicillin-resistant (MRSA), with strong biofilm-forming capacity and a potential association with prolonged hospitalization. Vigilance is warranted against potential outbreaks of the predominant MRSA-SCV clone ST1-t128, as well as the severe drug resistance observed in ST764-t1084 MRSA-SCVs.

Purpose: Talaromycosis is an invasive fungal infection caused by the pathogenic fungus Talaromyces marneffei (T. marneffei), prevalent in Southeast Asia and Southern China. This disease is rare in non-endemic areas and primarily affects the respiratory system with atypical manifestations. Therefore, the condition is often misdiagnosed as other respiratory infections. This article presents two cases of talaromycosis in non-endemic areas, aiming to provide diagnostic and therapeutic references for this rare fungal infection.

Case presentation: Two cases of talaromycosis in non-endemic areas were retrospectively analyzed. The first case involved a human immunodeficiency virus (HIV)-infected patient with tracheobronchial talaromycosis. Bronchoscopy revealed multiple nodular neoplasms in the trachea and bilateral main bronchi. Histopathological examination of the biopsy tissue showed histiocyte aggregation and intracellular pathogens. T. marneffei was identified by microbial culture of bronchoalveolar lavage fluid (BALF). The second case was an HIV-negative patient with pulmonary talaromycosis. Bronchoscopy revealed mucosal congestion and edema, and T. marneffei was detected by metagenomics next-generation sequencing (mNGS) of BALF.

Conclusion: Talaromycosis warrants more clinical attention in both HIV-negative individuals and non-endemic areas. In addition, clinicians should improve diagnostic recognition of this disease for timely management. Bronchoscopy combined with mNGS can facilitate early diagnosis of talaromycosis, particularly in culture-negative cases where conventional methods fail. This strategy directly addresses a major diagnostic challenge and improves patient prognosis.

Objective: The Candida genus has become an important pathogen of urinary tract infections (UTIs). Systemic infections caused by Candida could result in high mortality and significant medical costs, presenting an increasingly severe clinical challenge. This five-year retrospective study was designed to investigate the species distribution, antifungal resistance patterns and clinical risk factors associated with Candida urinary tract infections, it is critical to guide the rational selection of antifungal agents and optimize clinical management strategies.

Methods: This retrospective study analyzed 229 cases of Candida UTIs diagnosed at the Third Medical Center of the Chinese PLA General Hospital between 2020 and 2024. Species distribution and antifungal susceptibility were evaluated using chi-square tests, while multivariate logistic regression was employed to identify independent risk factors.

Results: 1. A total of 230 Candida strains were isolated from 229 patients (138 males and 91 females). The detection rate of C. albicans decreased from 47.06% in 2020 to 39.22% in 2024, with a corresponding rise in non-albicans species.2. Among the 199 strains tested for antifungal susceptibility, all isolates remained fully susceptible to amphotericin B and 5-fluorocytosine (0.00% resistance). In contrast, resistance to azole antifungals was notably higher. C. tropicalis exhibited significantly greater resistance to triazole agents compared to C. albicans (P<0.05), while C. glabrata demonstrated a high resistance rate to itraconazole (44.00%), indicating a growing resistance concern. 3. Univariate analysis showed that hospital stays ≥14 days, urinary catheterization ≥7 days, and broad-spectrum antibiotic use were significantly associated with Candida UTIs (P<0.05). Multivariate logistic regression identified prolonged hospitalization and catheterization as independent risk factors (P<0.05).

Conclusion: The increasing prevalence of non-Candida albicans species and rising azole resistance-particularly among Candida tropicalis-underscore the importance of routine species identification and antifungal susceptibility testing. Early urine culture screening and individualized antifungal selection are crucial, especially for patients with prolonged hospital stays or indwelling catheters, promoting the transition from empirical medication use to individualized treatment in clinical practice.

Background: Cystobasidium spp. are rare yeasts recently recognized as emerging human pathogens. This study presents the first report from China of Cystobasidium slooffiae isolated from human wound infections, and characterizes its microbiological profile, phylogenetic identity, and antifungal susceptibility.

Methods: Two strains were isolated from skin wounds of immunocompromised patients. They were characterized based on colony morphology on Sabouraud dextrose agar, Gram staining, MALDI-TOF MS analysis, Erg11 amino acid sequences analysis, and phylogenetic analysis using combined sequences of 18S rDNA, D1/D2 domains, and ITS regions. Antifungal susceptibility testing was performed according to CLSI guidelines (M27-A3/M60).

Results: The colonies transitioned from light yellow to orange within 48-96 h with Gram-positive budding cells. MALDI-TOF MS failed to identify accurately any of these strains. However, phylogenetic analysis of ITS confirmed that both strains were C. slooffiae. Both strains exhibited high minimum inhibitory concentrations (MICs) for all three echinocandins (>8 µg/mL) and fluconazole (32-64 µg/mL), whereas the MICs for isavuconazole were in the range 0.75-1 µg/mL. Erg11 sequence analysis revealed they formed a distinct clade that was genetically distant from Rhodotorulaceae.

Conclusion: Our findings showed that C. slooffiae could be an important emerging, opportunistic human invasive fungal pathogen because of its reduced susceptibility to echinocandins and fluconazole.

Background: Candidemia, a bloodstream infection caused by Candida species, poses a significant clinical challenge, especially in immunocompromised individuals and intensive care unit (ICU) patients. Prompt diagnosis and treatment are crucial, as delayed antifungal therapy is associated with higher mortality rates. This study, conducted at King Abdulaziz University Hospital (KAUH) in Saudi Arabia, aimed to investigate the clinical and microbiological aspects of candidemia.

Methods: This study is a retrospective analysis, KAUH in Saudi Arabia, using data from January 2017 to March 2021. Advanced fungal diagnostic technologies, including MALDI-TOF MS, BioFire, and Vitek 2 systems, were utilized. Patient demographics, clinical characteristics, Candida species distribution, and antifungal susceptibility were assessed. Univariate, bivariate, and multivariate statistical analyses were conducted.

Results: Among 418 patients, Candida albicans was the most prevalent species (32.1%), followed by C. tropicalis (23.4%) and C. parapsilosis (18.4%). Various Candida species exhibited different antifungal susceptibility patterns, with high sensitivity to Amphotericin B (95%) and Fluconazole (94%). Sensitivity to Caspofungin varied significantly among species (p = 0.023), with C. parapsilosis showing the highest sensitivity (95%). The overall mortality rate was 67%. None of Candida Species exhibited a statistically significant association with death, however other factors including age, autoimmune diseases, and dialysis were associated with increased mortality risk.

Conclusion: This study provides valuable insights into the epidemiology and clinical characteristics of candidemia at KAUH, highlighting the importance of species identification and tailored antifungal therapy. These findings can inform strategies to improve patient care and infection control in Saudi Arabian healthcare settings, contributing to global efforts to mitigate the impact of invasive fungal infections.

Purpose: This study aims to conduct a whole-genome analysis of the isolated strain HhutSZ1, providing more reliable clinical experience for the treatment of patients infected with such bacteria.

Patients and methods: A patient with IgA nephropathy failed to respond to treatment with ciprofloxacin for an infection. A rare strain of Herbaspirillum was isolated from the patient's blood. The VITEK MS Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) System and VITEK 2 Automated Microbial Identification System were used to conduct a preliminary identification and antibiotic susceptibility tests. Then we performed whole-genome sequencing of this strain along with comparative genomic analysis.

Results: VITEK 2 System identified HhutSZ1 as Burkholderia cepacia, while the VITEK MS System identified it as Herbaspirillum huttiense with a high confidence coefficient. The phylogenetic tree based on the 16S rRNA gene showed that HhutSZ1 belonged to the genus Herbaspirillum. Average Nucleotide Identity (ANI) analysis showed that the scores of this strain compared with other Herbaspirillum huttiense strains were all lower than 95, confirming that this strain did not belong to Herbaspirillum huttiense. The patient's infection failed to resolve despite ciprofloxacin treatment. Subsequent antimicrobial susceptibility testing revealed that HhutSZ1 exhibited intermediate resistance to ciprofloxacin, which is consistent with the clinical treatment failure. Six genes were detected in the Comprehensive Antibiotic Resistance Database (CARD). And among them, five RND family efflux pump genes resistant to fluoroquinolone were all located on chromosomes.

Conclusion: For the genus Herbaspirillum, mass spectrometry identification cannot accurately identify the species. The analysis based on 16s rRNA combined with ANI can be more accurate. Some Herbaspirillum spp may have inherent resistance to fluoroquinolone antibiotics. In conclusion, our findings suggest that the low detection rate and low drug resistance of this strain cannot be overlooked, and the study provides valuable clinical insight for managing infections in immunocompromised patients.

Objective: To investigate the contribution of bla _IMP-45 and its plasmid-borne genetic context in the development of imipenem heteroresistance in Pseudomonas aeruginosa.

Methods: Six clinical isolates of P. aeruginosa (HN41, HN66, HN67, HN125, HN148, and HN232) were analyzed. Broth microdilution confirmed imipenem(IMP) resistance in all the strains (MIC ≥8 mg/L). Whole-genome sequencing was performed to identify the presence of bla _IMP-45. E-test strips were used to indicate suspected heteroresistance phenotypes, while Population Analysis Profile (PAP) assays were conducted to definitively classify the strains. Complete plasmid sequencing of HN232 (IMP-HR) and HN41 (IMP-NHR) was performed to identify the genetic context of bla _IMP-45. Pre-exposure of IMP-HR strain HN232 to sub-inhibitory IMP (1, 4, and 32 mg/L) for 24h was conducted to assess regrowth frequency. Quantitative reverse-transcription PCR (qRT-PCR) and digital PCR (ddPCR) were used to measure bla _IMP-45 expression and gene copy number.

Results: Whole-genome sequencing revealed the absence of bla _IMP-45 in the HN67 and HN125 strains. E-test strips indicated suspected heteroresistance phenotypes, while Population Analysis Profile (PAP) assays definitively classified HN66, HN148, and HN232 as heteroresistant (heteroresistant subpopulation inhibitory concentration, HIC/HNIC ratio ≥8), with their maximum permissive growth concentrations (256 mg/L) 32-fold higher than non-heteroresistant strains HN67 and HN125 (8 mg/L), implicating bla _IMP-45 in driving phenotypic heterogeneity. Complete plasmid sequencing of HN232 (IMP-HR) and HN41 (IMP-NHR) identified bla _IMP-45 within the In786 integron, embedded in the Tn7445 transposon (a Tn1403 derivative) on IncP-2 type plasmids. Notably, the bla _IMP-45-flanking genetic environment was conserved between HR and NHR strains, excluding promoter region variations (eg, PcH2 and P2 promoters within In786) as drivers of differential expression. Pre-exposure of IMP-HR strain HN232 to sub-inhibitory IMP (1, 4, and 32 mg/L) for 24h induced dose-dependent increases in regrowth frequency at 4 and 8 mg/L IMP. Quantitative reverse-transcription PCR (qRT-PCR) and digital PCR (ddPCR) demonstrated that low-dose IMP exposure (1 mg/L, 24h) upregulated bla _IMP-45 expression and increased the gene copy number in HN232, whereas the NHR strain HN41 exhibited stringent plasmid regulation.

Conclusion: The study provided critical insights into bla _IMP-45-mediated IMP heteroresistance in P. aeruginosa, highlighting plasmid-encoded amplifiable resistance determinants as key modulators of phenotypic adaptability under antibiotic pressure.

Purpose: Organophosphate (OP) poisoning, a frequent method of suicide in the Asia-Pacific region and rural areas, inhibits cholinesterase (ChE), causing an acute cholinergic crisis. Pneumonia occurs in 20-50% of these cases, contributing to disease severity and mortality. However, data on the causative pathogens and the risk of drug-resistant bacteria in this patient population are limited. Thus, our study aimed to address these gaps.

Patients and methods: This retrospective cohort study (April 2011-March 2023) investigated patients admitted to the intensive care unit (ICU) or emergency medical center at Niigata University Medical & Dental Hospital with acute OP poisoning. Data on patient demographics, pneumonia diagnosis, sputum culture results, prior antibiotic use, and risk factors for drug-resistant bacteria were collected. We also analyzed the detection rates of methicillin-resistant Staphylococcus aureus and SPICE (Serratia, Pseudomonas, indole-positive Proteus, Citrobacter, and Enterobacter) organisms.

Results: Among the 21 patients with OP poisoning, 13 (62%) developed pneumonia and received antibiotic treatment. They had a longer ICU stay, higher Sequential Organ Failure Assessment scores on admission, and lower serum ChE activity (<100 IU/L). Gram-negative bacilli (GNB) were observed in five sputum cultures from 12 patients with pneumonia, with Pseudomonas aeruginosa isolated from three cases. None of the patients had known risk factors for drug-resistant bacteria.

Conclusion: Pneumonia in patients with OP poisoning was predominantly caused by GNB, particularly P. aeruginosa. Thus, despite the absence of known risk factors for drug-resistant bacteria, clinicians should consider the possibility of resistant pathogens when selecting empirical antibiotic therapy for pneumonia in these patients.

Background: Purulent meningitis caused by polymicrobial oral anaerobes represents a rare but life-threatening clinical challenge, with Porphyromonas endodontalis, Bacteroides heparinolyticus, Prevotella pleuritidis, and Streptococcus constellatus being pfastidious organisms. Traditional diagnostic methods often fail to identify these fastidious organisms, leading to delayed or inappropriate therapy.

Case presentation: We report a rare case of purulent meningitis resulting from a polymicrobial infection involving Porphyromonas endodontalis, Bacteroides heparinolyticus, Prevotella pleuritidis, and Streptococcus constellatus in a 76-year-old male patient who presented with a 40-day history of left facial pain. This case represents the first documented instance of these four oral anaerobes concurrently causing an infection of the central nervous system.

Conclusion: To the best of our knowledge, this case represents the first documented evidence of polymicrobial purulent meningitis caused by oral anaerobes, specifically Porphyromonas endodontalis, Bacteroides heparinolyticus, Prevotella pleuritidis, and Streptococcus constellatus. Our findings not only provide direct evidence for the oral-central nervous system (CNS) infection pathway but also validate that the valuable approach based on metagenomic next-generation sequencing (mNGS) offers significant clinical insights for diagnostic and therapeutic strategies.