A retrospective cohort study assessing acute kidney injury and renal recovery among septic patients empirically treated with vancomycin piperacillin-tazobactam versus vancomycin cefepime

Vancomycin plus piperacillin-tazobactam (VPT) is a commonly used antimicrobial regimen for septic patients. VPT is more nephrotoxic than other regimens such as vancomycin plus cefepime (VC) when given over several days. This risk of nephrotoxicity is less clear when VPT is given for initial empiric therapy in sepsis and de-escalated quickly based on evolving clinical information. The objective of this study was to assess nephrotoxicity among septic patients empirically treated with either VPT or VC at initial clinical presentation. We conducted a retrospective study of septic patients who received VPT or VC within 12 h of presentation to the emergency department. The primary outcomes were acute kidney injury (AKI) and renal recovery 72 h after presentation. For the total of 418 patients, 306 received VPT and 112 received VC. Rates of AKI at 72 h were 15.2% for VPT patients and 11.0% for VC patients [p = 0.44]. Among patients with AKI at presentation, 16.3% of VPT patients had AKI at 72 h compared to 8.9% of VC patients [p = 0.19]. Among those without AKI at presentation, 14.2% VPT patients and 16.7% VC patients had AKI at 72 h [p = 0.71]. Renal recovery rates for patients with AKI at presentation were 42.3% for VPT patients versus 40.3% for VC patients [p = 0.78]. In-hospital renal replacement therapy occurred in 6.2% VPT patients and 0.9% VC patients [p = 0.024]. Therefore, initial empiric therapy with VPT in sepsis may not confer increased risk of AKI when de-escalated appropriately.

An excess of rare genetic variation in ABCE1 among Yorubans and African-American individuals with HIV-1

Signatures of natural selection occur throughout the human genome and can be detected at the sequence level. We have re-sequenced ABCE1, a host candidate gene essential for HIV-1 capsid assembly, in European- (n=23) and African-descent (Yoruban; n=24) reference populations for genetic variation discovery. We identified an excess of rare genetic variation in Yoruban samples, and the resulting Tajima's D was low (-2.27). The trend of excess rare variation persisted in flanking candidate genes ANAPC10 and OTUD4, suggesting that this pattern of positive selection can be detected across the 184.5 kb examined on chromosome 4. Owing to ABCE1's role in HIV-1 replication, we re-sequenced the candidate gene in three small cohorts of HIV-1-infected or resistant individuals. We were able to confirm the excess of rare genetic variation among HIV-1-positive African-American individuals (n=53; Tajima's D=-2.34). These results highlight the potential importance of ABCE1's role in infectious diseases such as HIV-1.

Sonicated diagnostic immunoblot for bartonellosis

Two simple Bartonella bacilliformis immunoblot preparation methods were developed. Antigen was prepared by two different methods: sonication of whole organisms or glycine extraction. Both methods were then tested for sensitivity and specificity. Well-defined control sera were utilized in the development of these diagnostic immunoblots, and possible cross-reactions were thoroughly examined. Sera investigated for cross-reaction with these diagnostic antigens were drawn from patients with brucellosis, chlamydiosis, Q fever, and cat scratch disease, all of whom were from regions where bartonellosis is not endemic. While both immunoblots yielded reasonable sensitivity and high specificity, we recommend the use of the sonicated immunoblot, which has a higher sensitivity when used to detect acute disease and produces fewer cross-reactions. The sonicated immunoblot reported here is 94% sensitive to chronic bartonellosis and 70% sensitive to acute bartonellosis. In a healthy group, it is 100% specific. This immunoblot preparation requires a simple sonication protocol for the harvesting of B. bacilliformis antigens and is well suited for use in regions of endemicity.