Failure of the first step of two-stage revision due to polymicrobial prosthetic joint infection of the hip

Background

The unsuccessful treatment of prosthetic joint infection (PJI) with two-stage revision leads to infection recurrence. The objectives of the study were to assess the clinical and demographic characteristics of patients with polymicrobial PJI, and to evaluate the role of the microbial profile involved in PJI in the risk of infection recurrence after the first step of two-stage revision surgery.

Materials and methods

A retrospective analysis of 189 cases of culture-positive PJI following total hip replacement over a 5-year period was performed. The demographic characteristics of patients, clinical symptoms, microbiology cultures of intraoperative biopsies, laboratory values of C-reactive protein (CRP), white blood cell count and erythrocyte sedimentation rate were analyzed. Patients were divided into two groups—135 with monomicrobial and 54 with polymicrobial infection.

Results

Of all patients, 68.9 % in the monomicrobial and 83.3 % in the polymicrobial group had a body mass index >25 kg/m² (p = 0.05). The median CRP values were 5.7 mg/L (IQR 4.0–10.0 mg/L) in the monomicrobial compared to 8.8 mg/L (IQR 5.0–27 mg/L) in the polymicrobial group (p = 0.01). The percentage of successful outcomes was 27.8 % in patients with microbial associations (p < 0.0001). Gram-negative pathogens caused polymicrobial PJI in 61.5 % of cases with infection recurrence (OR 4.4; 95 % CI 1.18–16.37; p = 0.03).

Conclusions

Overweight and obese patients or those with elevated CRP had a greater risk of polymicrobial PJI. They were predisposed to recurrence of infection after the first step of two-stage revision. An unsuccessful outcome was more likely in cases with polymicrobial infection compared to those with monomicrobial infection. In addition, the presence of multidrug-resistant strains of Gram-negative bacteria substantially increased the risk of PJI treatment being unsuccessful.

Level of evidence

Level III, therapeutic study.

     

Gating of the HypoPP-1 mutations: I. Mutant-specific effects and cooperativity

Hypokalemic periodic paralysis type 1 (HypoPP-1) is a hereditary muscular disorder caused by point mutations in the gene encoding the voltage-gated Ca²⁺ channel α subunit (Ca_v1.1). Despite extensive research, the results on HypoPP-1 mutations are minor and controversial, as it is difficult to analyse Ca²⁺ channel activation macroscopically due to an existence of two open states. In this study, we heterologously expressed the wild-type and HypoPP-1 mutations introduced into the rabbit cardiac Ca²⁺ channel (R650H, R1362H, R1362G) in HEK-293 cells. To examine the cooperative effects of the mutations on channel gating, we expressed two double mutants (R650H/R1362H, R650H/R1362G). We performed whole-cell patch-clamp and, to obtain more information, applied a global fitting procedure whereby several current traces elicited by different potentials were simultaneously fit to the kinetic model containing four closed, two open and two inactivated states. We found that all HypoPP-1 mutations have “loss-of-function” features: D4/S4 mutations shift the equilibrium to the closed states, which results in reduced open probability, shorter openings and, therefore, in smaller currents, and the D2/S4 mutant slows the activation. In addition, HypoPP-1 histidine mutants favored the second open state O₂ with a possibly lower channel selectivity. Cooperativity between the D2/S4 and D4/S4 HypoPP-1 mutations manifested in dominant effects of the D4/S4 mutations on kinetics of the double mutants, suggesting different roles of D2/S4 and D4/S4 voltage sensors in the gating of voltage-gated calcium channels. Alexey Kuzmenkin and Chao Hang contributed equally to this work.     

Aetiological risk factors are associated with distinct imaging findings in patients with chronic pancreatitis: A study of 959 cases from the Scandinavian Baltic Pancreatic Club (SBPC) imaging database

ObjectivesThe relation between aetiology and structural changes of the pancreas in patients with chronic pancreatitis (CP) is not fully understood. Earlier studies are limited by focusing on selected factors in studies of limited sample size. We aimed to use a large dataset to explore associations between aetiology and pancreatic morphology in CP.MethodsSubjects with definite or probable CP according to the M-ANNHEIM diagnostic criteria were included in this multicentre cross-sectional observational study and assessed using a standardized and validated CP imaging system. We performed multivariate logistic regression to analyse if aetiological factors adjusted for covariates were independently associated with morphological pancreatic features.ResultsWe included 959 patients (66% males). Mean (SD) age was 55 (14) years. Pancreatic structural changes were found in 94% of the subjects: 67% had calcifications, 59% main pancreatic duct dilatation, 33% pseudo-cysts and 22% pancreatic atrophy. Alcohol abuse was independently associated with pancreatic calcifications (odds ratio (OR, [95% CI]); 1.61, [1.09, 2.37]) and focal acute pancreatitis (OR; 2.13, [1.27, 3.56]), whereas smoking was independently associated with more severe calcifications (OR; 2.09, [1.34, 3.27]) and involvement of the whole gland (OR; 2.29, [1.61, 3.28]). Disease duration was positively associated with calcifications (OR; (per year) 1.05 [1.02, 1.08]) and pancreatic atrophy (OR; 1.05 [1.02, 1.08]) and negatively associated with focal acute pancreatitis (OR 0.91, [0.87, 0.95] and pseudo cysts (OR; 0.96, [0.93, 0.98]).ConclusionIn this large-scale study, etiological risk factors and disease duration in CP were independently associated with specific structural pancreatic imaging changes.     

Vertical Transmission of SARS-CoV-2 in Second Trimester Associated with Severe Neonatal Pathology

The effects of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in women on the gestation course and the health of the fetus, particularly in the first and second trimesters, remain very poorly explored. This report describes a case in which the normal development of pregnancy was complicated immediately after the patient had experienced Coronavirus disease 2019 (COVID-19) at the 21st week of gestation. Specific conditions included critical blood flow in the fetal umbilical artery, fetal growth restriction (1st percentile), right ventricular hypertrophy, hydropericardium, echo-characteristics of hypoxic-ischemic brain injury (leukomalacia in periventricular area) and intraventricular hemorrhage at the 25th week of gestation. Premature male neonate delivered at the 26th week of gestation died after 1 day 18 h due to asystole. The results of independent polymerase chain reaction (PCR), mass spectrometry and immunohistochemistry analyses of placenta tissue, umbilical cord blood and child blood jointly indicated vertical transmission of SARS–CoV-2 from mother to the fetus, which we conclude to be the major cause for the development of maternal vascular malperfusion in the studied case.