Carbapenemase-producing Klebsiella pneumoniae bloodstream infection in critically ill patients: risk factors and predictors of mortality.

A significant increase in carbapenemase-producing Klebsiella pneumoniae (CP-Kp) bacteraemias has been observed worldwide. The objective of the present work was to study the risk factors and predictors of mortality of CP-Kp bacteraemias among critically ill patients. During a 4-year period (2012-3015), a matched 1:2 case-control study was conducted. Klebsiella pneumoniae was identified by Vitek 2 technology. Antibiotic susceptibility was performed by the agar disc diffusion method and Etest. The presence of the bla KPC, bla VIM and bla NDM genes was confirmed by polymerase chain reaction (PCR). Epidemiologic data were collected from the intensive care unit (ICU) computerised database. One hundred and thirty-nine patients who developed a CP-Kp bacteraemia were matched with 278 patients. The majority of isolates (128; 92.1%) carried the bla KPC gene, seven carried both bla KPC and bla VIM, three bla VIM and one carried bla NDM. Risk factors for the development of CP-Kp bacteraemia were administration of tigecycline and number of antibiotics administered prior to CP-Kp bacteraemia. Overall, the 30-day mortality was 36.0%. Multivariate analysis revealed septic shock, Simplified Acute Physiology Score II (SAPS II) upon infection onset, adjunctive corticosteroid administration and parenteral nutrition as independent predictors of mortality, while treatment with a combination of appropriate antibiotics was identified as a predictor of good prognosis. Among septic shock patients (n = 74), Sequential Organ Failure Assessment (SOFA) score upon infection onset, adjunctive corticosteroid administration and strain carrying the bla KPC gene were independently associated with mortality, while the administration of combination treatment was identified as a predictor of a good prognosis. The administration of tigecycline predisposes to the induction of bacteraemia. Appropriate antibiotic treatment is associated with better survival, while concomitant corticosteroid treatment is associated with mortality.

Safety and effectiveness of alveolar recruitment maneuvers and positive end-expiratory pressure during general anesthesia for cesarean section: a prospective, randomized trial.

INTRODUCTION: During cesarean section, the supine position reduces functional residual capacity and worsens lung compliance. We tested the hypothesis that alveolar recruitment maneuvers and positive end-expiratory pressure improve lung compliance in women undergoing general anesthesia for cesarean section. METHODS: Ninety women undergoing cesarean section were randomly assigned to one of two groups in a prospective, double-blind trial. In the alveolar recruitment maneuver group, pressure-control ventilation was used and inspiratory time was increased to 50% after delivery; positive end-expiratory pressure was increased to 20cmH2O and peak airway inspiratory pressure gradually increased to 45-50cmH2O. Volume-control ventilation was then used with low tidal volumes (6mL/kg) and positive end-expiratory pressure was reduced stepwise to 8cmH2O. In the control group, alveolar recruitment maneuvers were not used. Data were collected before and 3, 10 and 20min after the alveolar recruitment maneuver, before extubation and postoperatively at 10 and 20min. RESULTS: Dynamic compliance, peak airway inspiratory pressure, PaO2 and PaO2/FiO2 were significantly different in the alveolar recruitment maneuver group compared to controls at all time points during surgery except at baseline. Oxygen saturation was significantly greater in the alveolar recruitment maneuver group at 10 and 20min and before extubation. Dynamic compliance was 29.7-42.5% higher and peak airway inspiratory pressure 3.6-10.2% lower in the alveolar recruitment maneuver group compared to controls. The PaO2, PaO2/FiO2 and oxygen saturation were higher (9.4-12%, 10.3-11.9% and 0.4-1.3%, respectively) in the alveolar recruitment maneuver group. Postoperatively, PaO2 and oxygen saturation were significantly higher in the alveolar recruitment maneuver group compared to controls (PaO2 9.2% at 10min and 8.4% at 20min, oxygen saturation 0.8% at 10min and 1.1% at 20min). There were no significant differences in hemodynamic stability or adverse events between groups. CONCLUSION: Compared to standard care, the alveolar recruitment maneuver with positive end-expiratory pressure and low tidal volumes appears safe and effective in improving lung compliance and both intraoperative and postoperative oxygenation in women undergoing general anesthesia for elective cesarean section.

Pitfalls in the identification of Enterococcus species and the detection of vanA and vanB genes.

UNLABELLED: The aims were to assess the performance of Vitek 2 in identifying enterococcal species and the implementation of GeneXpert(®) vanA/vanB PCR for the detection of vancomycin-resistant enterococci (VRE). Gram-positive cocci from clinical and environmental specimens (n = 431) suspicious of being enterococci by conventional methods were evaluated by Vitek 2. This system identified 296 Enterococcus faecium, 87 Enterococcus faecalis, 10 Enterococcus villorum, 9 Enterococcus gallinarum, 9 Enterococcus durans, 5 Enterococcus casseliflavus, 1 Enterococcus spp. and 14 isolates as Non-Enterococcus. All strains were submitted to pulsed field gel electrophoresis (PFGE) analysis showing 64 banding patterns. Representative strains from each banding pattern were further characterized to species level by 16S rDNA sequencing. The misidentification rate by Vitek 2 to species level among 429 molecularly identified enterococci was 6% (26 isolates). Additionally, 372 rectal swabs were obtained from critically ill patients. They were evaluated for the presence of VRE by ChromID VRE combined with in-house PCR vs GeneXpert(®) . GeneXpert(®) showed high (>92%) sensitivity, specificity, accuracy for vanA-positive Enterococcus detection, as well as, sensitivity and specificity for vanB-positive strains. Positive predictive value for detection of vanB-positive enterococci by GeneXpert(®) vanA/vanB was low (30%). GeneXpert(®) showed the same efficacy as ChromID VRE in detecting vanA-positive enterococci, but lower for vanB-gene detection. SIGNIFICANCE AND IMPACT OF THE STUDY: The study shows that even though the performance of Vitek 2 Advanced Expert System was good in identifying enterococci to species level, it is important to verify results by a molecular method when phenotypic findings are discordant with epidemiologic patterns. Furthermore, GeneXpert(®) vanA/vanB PCR and ChromID VRE combined with in-house PCR were applied in rectal samples for the detection of VRE colonization among critically ill patients. GeneXpert(®) showed an excellent performance in detecting vanA-positive enterococci, but false-positive results for vanB-gene detection render its application problematic in departments with high incidence of vanB-positive enterococci.

Number of positive blood cultures, biofilm formation, and adhesin genes in differentiating true coagulase-negative staphylococci bacteremia from contamination.

The significance of the number of coagulase-negative staphylococci (CNS)-positive blood cultures remains obscure in regards to determining true bacteremia versus contamination. The goal of this study was to determine the predictors of real CNS bloodstream infection among intensive care unit (ICU) patients. ICU patients with at least one CNS-positive blood culture were identified from the microbiology database. Biofilm formation was tested by glass tube and microtiter plate assay. mecA gene, ica operon genes (icaA, icaB, icaD), and adhesin genes (aap, bap, atlE, fbe, fnbA) were detected by polymerase chain reaction (PCR). CNS were recovered from 120 septic episodes, 20 of which were true CNS bacteremias, whereas from the remaining 100 episodes, the isolated CNS were characterized as contaminants. The number of positive blood cultures was significantly associated with true CNS bacteremia. Nineteen true bacteremic Staphylococcus epidermidis strains were compared to 38 contaminants. Biofilm synthesis was documented in 37 isolates associated with the presence of the ica operon (p = 0.048). There were 39, 26, 38, 21, and 10 strains positive for the presence of atlE, bap, fbe, aap, and fnbA genes, respectively. Rifampicin resistance, absence of severe sepsis, number of S. epidermidis-positive blood cultures, and absence of the bap gene were independently associated with true S. epidermidis bacteremia as compared to contaminant strains. The number of positive blood cultures is associated with true CNS bacteremia. The presence of adhesin genes may play a role in differentiating true infection from contamination, whereas absence of the bap gene is associated with true S. epidermidis bacteremia.

Co-colonization by multidrug-resistant bacteria in two Greek intensive care units.

Our goal was to identify the risk factors for co-colonization by KPC-producing Klebsiella pneumoniae (KPC-Kp), vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA) upon intensive care unit (ICU) admission and during stay. Rectal and nasal samples were taken from each patient upon admission at two Greek ICUs and each week afterwards, and were inoculated onto chromogenic agar. Representative colonies were characterized with standard methods and Vitek-2 technology. The presence of the bla KPC gene (K. pneumoniae isolates), vanA and vanB (Enterococcus faecium and E. faecalis isolates), and mecA (S. aureus isolates) was confirmed by polymerase chain reaction (PCR). Upon ICU admission, among 481 patients, 59 (12%), 63 (13%), and 20 (4%) were colonized by KPC-Kp, VRE, or MRSA, respectively. Simultaneous colonization by KPC-Kp and VRE upon admission (34 patients) was associated with the number of co-morbidities [adjusted odds ratio (aOR): 1.5; confidence interval (CI) 1.0-2.5], administered antibiotics (aOR: 1.7; CI 1.3-2.3), and prior KPC-Kp infection (aOR: 24.4; CI 1.5-396.0). Among patients with an ICU stay of more than 6 days, 181 (73%), 31 (13%), and 9 (4%) became KPC-Kp, VRE, or MRSA colonized during ICU stay, respectively. KPC-Kp colonization was an independent risk factor for VRE colonization upon admission (aOR: 2.7; CI 1.0-7.2) and during stay (aOR: 7.4; CI 2.0-27.4), whereas VRE colonization was a risk factor for KPC-Kp upon admission (aOR: 5.1; CI 1.9-13.9) and MRSA colonization upon admission (aOR: 3.5; CI 1.2-10.1) and during ICU stay (aOR: 14.5; CI 2.1-100.1). Colonization by a multidrug pathogen could promote colonization by another.

Risk factors for enterococcal infection and colonization by vancomycin-resistant enterococci in critically ill patients.

PURPOSE: Vancomycin-Resistant Enterococci (VRE) are important causes of Intensive Care Unit (ICU) infections. Our goal was to identify the prevalence and risk factors for VRE colonization upon ICU admission and during ICU stay, as well as, their impact in enterococcal infection including vancomycin-susceptible cases (VSE). METHODS: A prospective study regarding patients admitted in ICU (n = 497) was conducted during a 24-month period. Rectal swabs were collected upon admission and during hospitalization and inoculated onto selective medium. Enterococci were phenotypically characterized. van genes were investigated by PCR and clones were identified by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing. Epidemiologic data were collected from the ICU database. RESULTS: Risk factors for VRE carriage upon ICU admission (71/497) were: duration of previous hospitalization, glycopeptide administration, chronic heart failure, malignancy, insulin-dependent diabetes mellitus, and previous enterococcal infection (VRE and/or VSE). Risk factors for VRE colonization during ICU stay (36/250) were: quinolone administration, chronic obstructive pulmonary disease, chronic renal failure, and number of VRE-positive patients in nearby beds. Risk factors for enterococcal infection during ICU stay (15/284), including VRE and VSE cases, were: administration of third- or fourth-generation cephalosporins, cortisone use before ICU admission and VRE colonization, whereas, enteral nutrition was a protective factor. CONCLUSIONS: Previous VRE colonization and antibiotic usage are essential parameters for enterococcal infection (by VRE or VSE) during ICU stay. Previous enterococcal infection, co-morbidities and antibiotic usage are associated with VRE colonization upon ICU admission, whereas, patient to patient transmission, co-morbidities and antibiotic usage constitute risk factors for VRE colonization during ICU hospitalization.

The role of colonization pressure in the dissemination of colistin or tigecycline resistant KPC-producing Klebsiella pneumoniae in critically ill patients.

PURPOSE: To identify the risk factors for incident enteric colonization by KPC-producing Klebsiella pneumoniae (KPC-Kp) resistant to colistin or tigecycline during Intensive Care Unit (ICU) stay. METHOD: A prospective observational study of patients admitted to the ICU was conducted during a 27-month period. Rectal samples taken upon admission and weekly afterwards were inoculated on selective chromogenic agar. K. pneumoniae isolates were characterized by standard methodology. Mean inhibitory concentration (MIC) to colistin and tigecycline were determined by E-test. The presence of bla KPC gene was confirmed by PCR. RESULTS: Among 254 patients, 62 (24.4%) became colonized by colistin- resistant KPC-Kp during their stay. Multivariate analysis revealed that corticosteroid, colistin administration and number of colonized patients in nearby beds per day were significantly associated with colonization. Among 257 patients, 39 (17.9%) became colonized by tigecycline resistant KPC-Kp during their stay. Risk factors identified by multivariate analysis were: days at risk, obesity, number of colonized patients treated in nearby beds per day and administration of tigecycline. CONCLUSIONS: The high prevalence of colistin or tigecycline resistant KPC-Kp enteric carriage in ICU patients indicate that dissemination is due to their transfer from patient to patient via the personnel and indicates the importance of strict infection control protocols.

Evaluation of the effects of autotransfusion of unprocessed blood on hemodynamics and oxygen transport in anesthetized pigs.

OBJECTIVE: To examine the hemodynamic effects and the oxygen transport pattern of autotransfusion of unprocessed blood on hemodynamics and oxygen transportation. DESIGN: Prospective, observational study. SETTING: Research laboratory of a university medical center. SUBJECTS: Six healthy, domestic pigs (20 - 33 kg). INTERVENTIONS: A left thoracotomy was performed and a 5-mm incision was created in the descending aorta, resulting in a controlled hemorrhage of 30 mL/kg (approximately 40% of blood volume) into the thoracic cavity over a 45-min time period. During that period, mean arterial pressure (MAP) was maintained slightly > 50 mm Hg, using intravenous lactated Ringers' solution. The blood sample was collected from the open thorax with compresses soaked in citric acid solution and then extracted by manual squeezing, filtered through several layers of gauzes, and stored in glass bottles. Repeat measurements were performed after hemorrhage, after retransfusion of the harvested blood, and thereafter every 15 mins up to 60 mins. The animals were supported for 2 more hrs and were observed for the following 48 hrs. MEASUREMENTS AND MAIN RESULTS: All animals survived and were in good condition 48 hrs after the experimental hemorrhage. The circulatory and oxygen transport response at the end of hemorrhage and concomitant maintenance of blood pressure at > 50 mm Hg resulted in: significant reductions of cardiac index, MAP, and oxygen transport (DO2) (46%, 50%, and 64% reductions, respectively, p < .01, in an increase of heart rate (HR) (+21%, not significant), pulmonary vascular resistance index (+112%, p < .05), and oxygen extraction (+105%, p < .01), as well as in a nonsignificant decrease of systemic vascular resistance index (-8%). After autotransfusion, the basic hemodynamic variables, MAP and HR were corrected, remaining near baseline (not significant) afterward. Cardiac index and DO2 increased after autotransfusion, but remained below the baseline until the end of the study protocol (p < .05). A significant increase was noticed for pulmonary arterial pressure and pulmonary vascular resistance index immediately after autotransfusion (p < .01). These values were corrected in part after 15 to 30 mins, but remained higher throughout the observaton period compared with baseline (29.5% and 89.8%, respectively, p < .05). The recently introduced relationship between cardiac index and oxygen extraction has been proposed to avoid problems of mathematical coupling between oxygen consumption and DO2 measurements. This relationship followed a similar course in all experiments throughout each phase. A shift downward and to the right represented the endpoint of the hemorrhagic phase. After autotransfusion, a shift toward baseline was noticed. Prothrombin time and partial thromboplastin time remained unchanged after autotransfusion. Free hemoglobin concentrations increased immediately after autotransfusion (+33%, p < .05), but returned to baseline values 48 hrs later. Histologic examination showed no changes in the examined organs. CONCLUSIONS: Reinfusion of large amounts of unprocessed blood (up to 40% of blood volume), collected with compresses from a noncontaminated surgical field is a cheap method, which may be of potential benefit in trauma patients, when more sophisticated autotransfusion devices are lacking. In the present study, this method resulted in transient but significant hemodynamic changes in the pulmonary circulation. Impairment of oxygen transport was noticed after the end of hemorrhage, but this impairment cannot be attributed to the autotransfusion technique alone, but also to factors such as hemorrhagic shock, surgical trauma, etc.