Diagnostic Utility of Platelet Count/Lymphocyte Count Ratio and Platelet Count/Mean Platelet Volume Ratio in Periprosthetic Joint Infection Following Total Knee Arthroplasty

BackgroundDiagnosing a periprosthetic joint infection (PJI) can be challenging and often requires a combination of clinical and laboratory findings. Monocyte/lymphocyte ratio, neutrophil/lymphocyte ratio, platelet/lymphocyte ratio (PLR), and platelet/mean platelet volume ratio (PVR) are simple predictors for inflammation that can be readily obtained from complete blood count. The aim of this study is to evaluate the diagnostic utility of these markers in predicting PJI in total knee arthroplasty (TKA) patients.MethodsA total of 538 patients who underwent revision TKA with calculable marker ratios prerevision in 2 groups were evaluated: (1) 206 patients with a preoperative diagnosis of PJI (group I) and (2) 332 patients treated for revision TKA for aseptic failures (group II). The diagnostic abilities of the markers were assessed via receiver operator characteristic curve analysis.ResultsThe optimal threshold of PVR at 30.82 had the highest sensitivity of 87.7%, while the optimal threshold of PLR at 234.13 had the highest specificity of 82.5%. Both PLR and PVR, when combined with Musculoskeletal Infection Society thresholds for erythrocyte sedimentation rate, C-reactive protein, synovial WBC, and PMN%, achieve significantly higher sensitivity and specificity rates for PJI at or above 97% (PLR: 99.03%; 98.80%; PVR: 98.54%;97.89%).ConclusionOur study demonstrates that PVR and PLR, which are readily available and inexpensive to obtain from complete blood counts, when combined with serum and synovial fluid markers have increased sensitivity and specificity comparable to that of alpha defensin. This suggests that PVR and PLR can be used together with other hematologic and aspirate markers to increase the accuracy of PJI diagnosis in TKA patients.     

Minority Race and Ethnicity is Associated With Higher Complication Rates After Revision Surgery for Failed Total Hip and Knee Joint Arthroplasty

BackgroundRacial and ethnic disparities in access to hip and knee total joint arthroplasty (TJA) and postoperative outcomes have wide-reaching implications for patients and the health care system. The aim of this study is to evaluate the effect of ethnicity on clinical outcomes and complications following revision hip and knee TJA.MethodsA single-institution, retrospective analysis of a consecutive series of 4424 revision hip and knee TJA patients was evaluated. Student’s t-test and chi-squared analysis were used to identify significant differences in patient demographics and clinical outcomes between Caucasians and various ethnic minorities, including African Americans, Hispanics, and Asians.ResultsWhen compared with white patients, African American patients demonstrated a significantly higher BMI (P = .04), ASA score (P = .04), length of hospital stay (P = .06), and postoperative infection rates (P = .04). Hispanics demonstrated a significantly higher BMI (P = .04), when compared with white patients, alongside a significantly higher risk for postoperative infection (P < .01). African American demonstrated a significantly higher ASA score (P = .02; P = .03), when compared with Hispanics and Asians, alongside a significantly increased length of stay (P = .01) and higher risk for postoperative infection (P = .02).ConclusionThe study findings demonstrate an underutilization of revision TJA by ethnic minority groups, suggesting that disparities in access to orthopedic surgery increase from primary to revision surgery despite higher failure rates of minority ethnic groups reported after primary TJA surgery. In addition, inferior postoperative outcomes were associated with African Americans and Hispanics, when compared to white patients, with African Americans demonstrating the highest risk of postoperative complications.     

Outcome of Debridement,Antibiotics, and Implant Retention With Modular Component Exchange in Acute Culture-Negative Periprosthetic Joint Infections

BackgroundModular component exchange and culture-directed antibiotic treatment is routinely employed for acute periprosthetic joint infection (PJI). However, as many as 7%-23% of PJIs have been reported to yield negative culture results. The efficacy of debridement, antibiotics, and implant retention (DAIR) with modular component exchange in the setting of acute culture negative PJI remains largely unknown. The aim of our study is to evaluate the outcomes of DAIR with modular component exchange in acute culture-positive and culture-negative PJI.MethodsA total of 149 consecutive patients with primary total joint replacements (90 total knee arthroplasties and 59 total hip arthroplasties) who underwent DAIR with modular component exchange for acute PJI with at least 3 years of follow-up were evaluated: (1) 46 culture-negative PJI patients and (2) 103 culture-positive PJI patients. Reinfection and aseptic revision rates along with complication rates were compared.ResultsThe reinfection rate for DAIR in acute culture-negative PJI was 13.0% compared to 19.4% in culture-positive PJI (P = .48). Mean survival time from reinfection between culture-negative (7.7 ± 0.4 years) and culture-positive (7.4 ± 0.3 years) PJI groups did not differ significantly (P = .40). Aseptic revision rates were 8.7% and 4.9% (P = .46), respectively, with loosening being the primary reason for implant failure in both cohorts.ConclusionsDespite lack of an identifying organism to guide postoperative antibiotic therapy, DAIR with modular component exchange for acute culture-negative PJI was associated with similar reinfection rates compared to acute culture-positive PJI, suggesting that culture negativity may not be a contraindication to DAIR in patients with acute PJI.     

Indian tick typhus presenting as Purpura fulminans

Seriously ill patients presenting with purpura fulminans, sepsis and multi-organ failure often require extensive diagnostic workup for proper diagnosis and management. Host of common infections prevalent in the tropics, e.g. malaria, dengue; other septicemic infections e.g. meningococcemia, typhoid, leptospirosis, toxic shock syndrome, scarlet fever, viral exanthems like measles, infectious mononucleosis, collagen vascular diseases (Kawasaki disease, other vasculitis) diseases, and adverse drug reactions are often kept in mind, and the index of suspicion for rickettsial illness is quite low. We present a case of Indian tick typhus presenting with purpura fulminans (retiform purpura all over the body), sepsis and multiorgan failure without lymphadenopathy and eschar, successfully treated with doxycycline and discharged home. Hence, a high index clinical suspicion and prompt administration of a simple therapy has led to successful recovery of the patient.     

Molecular characterization of African swine fever virus from outbreaks in Namibia in 2018

Five samples were collected from four suspected outbreaks of African swine fever in Namibia in 2018. Sequencing of the C‐terminus of the B646L gene (p72 protein), the central hypervariable region (CVR) of the B602L gene, the E183L gene (p54 protein) and the CD2v (used to determine the serogroup) was performed on DNA isolated from the samples. Phylogenetic analyses of the B646L (p72) revealed that one of the samples belonged to genotype I while the remaining samples could not be assigned to any currently known genotype. In contrast, by using the E183L gene three of the samples were shown to belong to genotype Id and only two were of unknown genotype. Based on the analysis of the partial CD2v amino acid sequences of four of the samples, one of the viruses clustered with serogroup 2 while the other three did not cluster within any of the eight known serogroups. Examination of the CVR identified three variants with 8, 18 and 24 tetrameric tandem repeat sequences. This study indicates that at least three different genetically distinct ASFV are currently present in Namibia.     

Rosiglitazone quantification in rat plasma using high performance liquid chromatography with mass spectrometric detection and its application to pre-clinical pharmacokinetic studies

A rapid and sensitive high performance liquid chromatography-mass spectrometry method has been developed for quantitative determination of Rosiglitazone, a thiazolidinedione drug used for the treatment of type II diabetes mellitus in rat plasma. The method was also validated as per International Conference on Harmonization (ICH) and Food and Drug Administration (FDA) guidelines. The analyte was extracted from rat plasma by the simple precipitation of plasma proteins technique using acetonitrile as a precipitating agent. Alprazolam was used as the internal standard. A Chromolith RP-18(e) column provided chromatographic separation of the analyte using a mobile phase containing 5mM ammonium acetate in water (pH 3) and methanol (20:80) at a flow rate of 1 mL/min with an elution time as low as 2.5 min, which was followed by detection with mass spectrometry. The mass transition ion-pair was followed as m/z 358.0 for rosiglitazone and m/z 308.8 for alprazolam. Simple isocratic chromatographic conditions and mass spectrometric detection of the method enable the detection of rosiglitazone at less than nanogram levels. The proposed method was found to be linear from 0.5 to 100 ng/mL (r(2) = 0.9987). The percent coefficient of variance for precision and accuracy values found at LLOQ (9.17), LQC (8.45), MQC (1.66) and HQC (1.53). The overall recovery of rosiglitazone was 95.9%. The developed and validated method was successfully applied for the pharmacokinetic studies of rosiglitazone tablets after a single oral dose to healthy Wistar rats. LAY ABSTRACT: A rapid and sensitive high performance liquid chromatography-mass spectrometry method has been developed and validated for quantification of rosiglitazone in rat plasma. The analyte was extracted from rat plasma by simple precipitation technique. Alprazolam was used as the internal standard. A Chromolith RP-18(e) column provided chromatographic separation of the analyte using a mobile phase containing 5mM ammonium acetate in water and methanol (20:80) at a flow rate of 1 mL/min which was followed by detection with mass spectrometry. The mass transition ion-pair was followed as m/z 358.0 for rosiglitazone and m/z 308.8 for alprazolam. The method involves precipitation of rosiglitazone from plasma, simple isocratic chromatography conditions and mass spectrometric detection that enables detection at less than nanogram levels. The proposed method has been validated with a linear range of 0.5 to100 ng/mL for rosiglitazone. The percent coefficient of variation for precision and accuracy are within 10%. The overall recovery of rosiglitazone was 95.9%. Total elution time was as low as 2.5 min. The developed and validated method was successfully applied for the pharmacokinetic studies of rosiglitazone tablets after a single oral dose to rats.