An invisible threat? Aspergillus positive cultures and co-infecting bacteria in airway samples.

BACKGROUND: Aspergillus fumigatus (Af) infection is associated with poor lung health in chronic suppurative lung diseases but often goes undetected. We hypothesised that inhibition of Af growth by Pseudomonas aeruginosa (Pa) increases the frequency of false-negative Af culture in co-infected people. Using a substantial group of cystic fibrosis (CF) airway samples, we assessed the relationship between Af and bacterial pathogens, additionally comparing fungal culture with next-generation sequencing. METHODS: Frequency of co-culture was assessed for 44,554 sputum/BAL cultures, from 1,367 CF patients between the years 2010-2020. In a subgroup, Internal Transcribed Spacer-2 (ITS2) fungal sequencing was used to determine sequencing-positive, culture-negative (S+/C-) rates. RESULTS: Pa+ samples were nearly 40% less likely (P<0.0001) than Pa- samples to culture Af, an effect that was also seen with some other Gram-negative isolates. This impact varied with Pa density and appeared to be moderated by Staphylococcus aureus co-infection. Sequencing identified Af-S+/C- for 40.1% of tested sputa. Samples with Pa had higher rates of Af-S+/C- (49.3%) than those without (35.7%; RR 1.38 [1.02-1.93], P<0.05). Af-S+/C- rate was not changed by other common bacterial infections. Pa did not affect the S+/C- rates of Candida, Exophiala or Scedosporium. CONCLUSIONS: Pa/ Af co-positive cultures are less common than expected in CF. Our findings suggest an Af-positive culture is less likely in the presence of Pa. Interpretation of negative cultures should be cautious, particularly in Pa-positive samples, and a companion molecular diagnostic could be useful. Further work investigating mechanisms, alternative detection techniques and other chronic suppurative lung diseases is needed.

Clinical characteristics of Pseudomonas and Aspergillus co-infected cystic fibrosis patients: A UK registry study.

BACKGROUND: Pseudomonas aeruginosa (Pa) and Aspergillus species (Asp) are the most common bacterial and fungal organisms respectively in CF airways. Our aim was to examine impacts of Asp infection and Pa/Asp co-infection. METHODS: Patients on the UK CF Registry in 2016 were grouped into: absent (Pa-), intermittent (Pai) or chronic Pa (Pac), each with Asp positive (Asp+) or negative (Asp-). Primary outcome was best percentage predicted FEV1 (ppFEV1) that year. Secondary outcomes were intravenous (IV) antibiotic courses, growth (height, weight, BMI) and additional disease complications. Associations between outcomes and infection-status were assessed using regression models adjusting for significant confounders (age, sex, Phe508del homozygosity and CF-related diabetes (CFRD)). RESULTS: 9,270 patients were included (median age 19 [IQR 9-30] years, 54% male, 50% Phe508del/F508del). 4,142 patients (45%) isolated Pa, 1,460 (16%) Asp. Pa-/Asp+ subjects had an adjusted ppFEV1 that was 5.9% lower than Pa-/Asp- (p < 0.0001). In patients with Pai or Pac, there was no additional impact of Asp on ppFEV1. However, there was a higher probability that Pac/Asp+ patients had required IV antibiotics than Pac/Asp- group (OR 1.23 [1.03-1.48]). Low BMI, ABPA, CF-liver disease and CFRD were all more frequent with Asp alone than Pa-/Asp-, though not more common in Pac/Asp+ than Pac/Asp-. CONCLUSIONS: Co-infection with Pa and Asp was not associated with reduced lung function compared with Pa alone, but was associated with additional use of IV antibiotics. Asp infection itself is associated with several important indicators of disease severity. Longitudinal analyses should explore the impact of co-infection on disease progression.

Delayed hepato-spleno-renal bypass for renal salvage following malposition of an infrarenal aortic stent-graft.

PURPOSE: To report a salvage maneuver for accidental coverage of both renal arteries during endovascular aneurysm repair (EVAR) of an infrarenal aortic aneurysm (AAA) and survey our surgical colleagues in the UK for their use of this bypass procedure. METHODS: A 74-year-old woman who had an EVAR complicated by renal failure secondary to malposition of the stent-graft underwent successful delayed renal revascularization with hepatorenal and splenorenal bypasses. This case prompted a literature review and preparation of an online 6-part questionnaire regarding the incidence and management of renal impairment following EVAR. The survey invitation was sent to all listed members of the Vascular Society of Great Britain and Ireland. RESULTS: Responses from 68 (10.5%) of the 650 vascular surgeons invited to participate in the survey were analyzed. The combined experience of those who completed the survey was >1500 EVAR procedures per annum. Forty percent (27/68) of the respondents had experienced a case of bilateral renal artery occlusion during EVAR. Two thirds (67%, 18/27) of these surgeons stated a preference for revascularizing the kidneys endovascularly, 7 surgeons would convert to open repair, 1 surgeon favored iliorenal bypass, and another suggested splenorenal bypass. Following intervention, 15 (56%) of 27 surgeons achieved revascularization that resulted in a return to baseline serum creatinine, 7 (26%) achieved partial recovery of the patient's serum creatinine, 3 (11%) had a patient on permanent dialysis, and 2 (7%) had patients who died (after open repair and endovascular procedure, respectively). CONCLUSION: Bilateral renal artery occlusion caused by malposition of a stent-graft is probably underreported. If revascularization of the kidneys by endovascular techniques fails, there is no consensus as to the optimal approach. Delayed revascularization should be considered if the kidneys show concentration of imaging contrast. Hepato-spleno-renal bypass, which has not heretofore been indicated for renal salvage post EVAR, can provide a good functional result in this situation.