Serial Evaluation of Abdominal Fluid and Serum Amino-terminal pro-C-type Natriuretic Peptide in Dogs with Septic Peritonitis

Diagnosis of Septic Body Cavity Effusion in Dogs and Cats: Cytology vs. Bacterial Culture

The elective test for the determination of the effusions etiopathogenesis is represented by physico-chemical analysis and cytology. Nevertheless, the bacterial culture and antibiotic sensitivity tests are crucial for setting therapy and for the outcome. This study compared cytology with microbiology in the etiologic diagnosis of exudative body cavity effusions in dogs and cats collected from October 2018 to October 2022. All samples underwent aerobic and anaerobic culture and cytology examination. Bacterial identifications were confirmed using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, whereas cytological samples were blindly evaluated either in May Grunwald-Giemsa (MGG) or Gram-stained samples by two board-certified clinical pathologists. A moderate agreement (κ = 0.454) between cytology and bacterial culture was revealed. The sensitivity of the cytological evaluation in our study ranged from 38.5% to 67.9%, and the specificity ranged from 88.9% to 100%, depending on the type of the effusion, so cytology may not be representative of the etiopathogenesis, whereas bacterial culture can misidentify or fail to isolate the correct pathogen for difficult in vitro growing due to the presence of inhibitory substances or contamination. Cytology and bacterial culture results for exudative body cavity effusions in dogs and cats can be misleading if conducted separately, so these two tests should be performed together to increase diagnostic accuracy.

Diagnostic utility of the total nucleated cell count for differentiation of septic and sterile peritoneal effusions in dogs

BACKGROUND

Rapid and accurate diagnosis of septic peritonitis is critical for initiating appropriate medical and surgical management.

OBJECTIVES

The aim of this study was to determine the diagnostic utility of the total nucleated cell count (TNCC), absolute neutrophil count, neutrophil percentage, and total protein (TP) to distinguish septic versus non-septic peritoneal effusions in dogs.

METHODS

Electronic medical records were retrospectively searched for peritoneal fluid samples from 2008 to 2018 and classified as septic or non-septic based on bacterial culture and/or cytology results. Receiver operator characteristic curves (ROCs) were used to describe the overall diagnostic utility of each test, with optimal cutpoints analyzed to dichotomize continuous variables. Positive and negative likelihood ratios were calculated at these cutpoints.

RESULTS

A total of 166 unique samples, including 87 septic and 79 non-septic peritoneal effusions, were included. There were no significant differences in dog sex, age, or days hospitalized between groups. Septic effusions had significantly higher TP, TNCC, absolute neutrophil count, and neutrophil percentage compared with non-septic effusions. The area under the curve of the ROC curves was TNCC (0.80), absolute neutrophil count (0.80), neutrophil percentage (0.64), and TP (0.63). For TNCC and absolute neutrophil count, optimal cutoffs were 17.13 × 103  cells/μL and 19.88 × 103  cells/μL, resulting in positive and negative likelihood ratios of 2.39 and 0.28 and 2.85 and 0.28, respectively.

CONCLUSIONS

Total nucleated cell counts and absolute neutrophil counts aid in the differentiation of septic and non-septic peritoneal effusions with similar diagnostic utility but are not sufficiently sensitive or specific to use without concurrent microscopic evaluation.

Association of the origin of contamination and species of microorganisms with short-term survival in dogs with septic peritonitis

OBJECTIVE

To assess the association between anatomical location of contamination and mortality in dogs with gastrointestinal and biliary origin of septic peritonitis.

METHODS

Medical records at two private referral hospitals between 2003 and 2020 were retrospectively reviewed. Cases were included if the origin of contamination was confirmed intraoperatively within the gastrointestinal or biliary tract. Cases were excluded if the dog died or was euthanized intraoperatively or where the data regarding the origin of contamination were not available. The association of anatomical origin with survival was assessed specifying the locations as stomach, small intestine, large intestine and biliary tract. The gastrointestinal tract origin was further subdivided into pylorus, nonpylorus, duodenum, jejunum, ileum, caecum and colon.

RESULTS

The overall survival rate was 75.9% (n = 44/58). There were no significant differences in survival among different anatomical origins of contaminations before or after subdivision (P = 0.349 and 0.832, respectively). Also, there was no association between isolated microorganism species in microbiological culture and the anatomical origin (P = 0.951) and the microorganism species was not associated with survival (P = 0.674).

CONCLUSIONS

There was no association between anatomical location of leakage, microorganism species and survival although further studies are warranted to analyse the relationships between anatomical leakage site and microorganism species as well as microorganism species and mortality.

Evaluation of Biomarkers from Peritoneal Fluid as Predictors of Severity for Abdominal Sepsis Patients Following Emergency Laparotomy

Purpose

Intra-abdominal infection is considered the second most common cause of sepsis and results in localized or diffused inflammation of the peritoneum. The main treatment for abdominal sepsis is an emergency laparotomy for source control. However, surgical trauma also causes inflammation, and patients become susceptible to postoperative complications. Therefore, it is necessary to identify biomarkers that can be used to distinguish sepsis from abdominal infection. This prospective study investigated whether cytokine levels in the peritoneum could predict complications and indicate severity of sepsis following emergency laparotomy.

Methods

We prospectively observed 97 patients with abdominal infection admitted to the Intensive Care Unit (ICU). After emergency laparotomy,SEPSIS-3 criteria were used for the diagnosis of sepsis or septic shock. Blood and peritoneal fluid samples were drawn at postoperative admission to the ICU and cytokine concentrations were measured by flow cytometry.

Results

Fifty-eight postoperative patients were enrolled. We found significant elevations in the peritoneal concentrations of IL-1β, IL-6, TNF-α, IL-17, and IL-2 in patients with sepsis or septic shock compared to the patients without sepsis after surgery. Positive correlations between levels of these peritoneal cytokines with APACHE II scores were found: IL-6, in particular, had the highest correlation coefficient of 0.833. Meanwhile, IL-10 in blood, MCP-1 and IL-8 in both blood and peritoneum were simultaneously increased in patients with sepsis and septic shock, and also positively correlated with disease severity.

Conclusion

The cytokine storm that occurs in the abdominal cavity after emergency laparotomy may be the main mechanism leading to sepsis. It may be valuable to measure IL-1β, IL-6, TNF-α,IL-17, IL-2, MCP-1, and IL-8 in the peritoneal fluid, combined with serum IL-10, MCP-1 and IL-8, in a panel of cytokines, to assess the severity of sepsis and predict mortality from abdominal infection after emergency laparotomy.

A feasibility study investigating the utility of a point-of-care rapid immunoassay for detecting septic peritoneal effusion in dogs

OBJECTIVE

To determine the sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy of a point-of-care urine bacterial rapid immunoassay (RIA) for a diagnosis of septic peritonitis, compared to more traditional diagnostic tools, such as cytology and bacterial culture.

DESIGN

Prospective, cross-sectional feasibility study conducted from October 2016 to June 2017.

SETTING

Four locations within a private practice referral hospital.

ANIMALS

Sixty-four dogs with peritoneal effusion of any etiology were enrolled. Four dogs were excluded due to absent RIA or bacterial culture results. Two additional dogs were excluded because of an inability to definitively classify them as having septic peritonitis.

INTERVENTIONS

Abdominocentesis was performed to obtain peritoneal effusion samples for aerobic and anaerobic bacterial culture, cytology, and RIA. Cytological slides were evaluated by a clinical pathologist following enrollment.

MEASUREMENTS AND MAIN RESULTS

Fifty-eight dogs were included in the study, 8 of which were classified as having septic peritonitis. Compared to final diagnosis of septic peritonitis, RIA had a low PPV (36.8%) but good NPV (97.4%) and was 77.5% accurate. SN of RIA (87.5%) to diagnose septic peritonitis was similar to cytology (85.7%) and bacterial culture (87.5%); however, SP was lower (76%, 100%, and 98%, respectively). Cytology had the best overall predictive values and accuracy for diagnosing septic peritonitis (PPV 100%, NPV 97.9%, and accuracy 98%) compared to RIA and bacterial culture.

CONCLUSIONS

RIA testing was similarly sensitive in identifying septic peritonitis compared to cytology and bacterial culture but was not very specific or accurate. As a stand-alone test, RIA commonly had false-positive test results, making it unreliable in identifying septic peritonitis. Cytology was the most accurate diagnostic test and had no false-positive results. Further investigation with a larger sample size and prevalence of septic peritonitis may prove beneficial.

Biomarker Guided Diagnosis of Septic Peritonitis in Dogs

Septic peritonitis (SP) is common in dogs and is associated with high mortality. Early recognition is essential to maximizing survival and may be aided by biomarker measurement. The present study aimed to evaluate the ability of biomarkers to discriminate septic peritonitis from non-septic ascites (NSA). Eighteen dogs with SP and 19 age-matched controls with NSA were enrolled. Contemporaneous blood and peritoneal effusion samples were obtained. Concentrations of cell-free DNA (cfDNA), cytokines, glucose, lactate, N-terminal pro-C-type natriuretic peptide (NT-proCNP), nucleosomes, and procalcitonin (PCT) were measured using commercial reagents and assays. Paired biomarker concentrations were compared with the Wilcoxon matched-pairs signed rank test, and biomarker concentrations between groups were compared with the Mann-Whitney U-test. P-values were adjusted for multiple comparisons using the Bonferroni correction. Receiver operating characteristic curves were generated to assess the ability of the above biomarkers to discriminate SP from NSA. Dogs with SP had significantly greater blood CCL2 concentrations than dogs with NSA (P = 0.032). Dogs with SP had significantly greater effusion CCL2, IL-6, IL-10, and lactate concentrations than dogs with NSA (P ≤ 0.0121). Blood-effusion concentration gradients of CCL2, glucose, IL-6, IL-10, and lactate were significantly different in dogs with SP compared to dogs with NSA (P ≤ 0.0165). Effusion lactate concentration had the highest AUROC value (0.866, 95% CI 0.751–0.980, P = 0.0001), although other biomarkers performed similarly. An effusion lactate concentration of 4.2 mmol/L was 72.2% (95% CI 46.5–90.3%) sensitive and 84.2% (95% CI 60.4–96.6%) specific for the diagnosis of SP.

Plasma procalcitonin concentrations predict organ dysfunction and outcome in dogs with sepsis

Background

Procalcitonin (PCT) is a valuable prognostic biomarker in human sepsis that is predictive of organ dysfunction, septic shock and mortality. Data on PCT in dogs is limited. This study aimed to investigate the prognostic value of baseline and serial PCT measurements in dogs with sepsis and to determine the association between PCT and sepsis severity and the presence of organ dysfunction. PCT concentrations were measured in citrated plasma samples collected from 53 dogs with sepsis at the time of admission (T0, n = 53) and at 24 h (T1, n = 35) and 48 h (T2, n = 30) post-admission using a commercial ELISA. Dogs were classified by sepsis severity (sepsis without organ dysfunction; severe sepsis; septic shock) and outcome (survivors; non-survivors). Organ dysfunctions were recorded at T0 and during hospitalization, and the APPLE_fast score calculated at T0. Healthy dogs (n = 12) were used as controls.

Results

There were 18 septic dogs without organ dysfunction, 24 dogs with severe sepsis and 11 with septic shock. Baseline PCT concentrations were significantly greater in dogs with sepsis compared to healthy controls (P < 0.0001), and in dogs with septic shock compared to dogs without cardiovascular compromise (P = 0.01). Baseline PCT was significantly correlated with organ dysfunction (P = 0.003). Declining PCT concentrations were documented in survivors at T1 and T2 compared to PCT at T0 (P = 0.0006), and PCT clearance at 24 h was significantly higher in survivors (n = 38) compared to non-survivors (n = 15) (P = 0.037). Canine APPLE_fast score was not predictive of sepsis severity, the development of MODS or outcome.

Conclusion

In dogs with sepsis, PCT concentrations at hospital admissions are predictive of organ dysfunction and septic shock. Serial procalcitonin monitoring may offer valuable prognostic information in canine sepsis, wherein early decreases in PCT concentrations are associated with survival.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1427-y) contains supplementary material, which is available to authorized users.