Serial Surveillance Cultures Research Articles

Acquisition of antimicrobial-resistant bacteria in the absence of antimicrobial exposure: A systematic review and meta-analysis.

The main risk factor for acquisition of antimicrobial-resistant bacteria (ARB) is antimicrobial exposure, although acquisition can occur in their absence. The aim of this study was to quantify the proportion of patients who acquire ARB without antimicrobial exposure. We searched Medline, Embase, and the Cochrane library for publications between January 1, 2000, and July 24, 2017, to identify studies of ARB acquisition in endemic settings. Studies required collection of serial surveillance cultures with acquisition defined as a negative baseline culture and a subsequent positive culture for an ARB, including either multidrug-resistant gram-negative bacteria or antimicrobial-resistant enterococci. Intervention studies were excluded. For each study, the proportion of patients who acquired an ARB but were not exposed to antimicrobials during the study period was quantified. A total of 4,233 citations were identified; 147 underwent full-text review. Of these, 10 studies met inclusion criteria; 7 studies were considered to be at low risk of bias; and 6 studies were conducted in the intensive care unit (ICU) setting. The overall summary estimate for the proportion of patients who were not exposed to antimicrobials among those who acquired an ARB was 16.6% (95% CI, 7.8%-31.8%; P < .001), ranging from 0% to 57.1%. We observed no heterogeneity in the ICU studies but high heterogeneity among the non-ICU studies. In most included studies, a subset of patients acquired an ARB but were not exposed to antimicrobials. Future studies need to address transmission dynamics of ARB acquisition in the absence of antimicrobials.

Severe ventilator-associated pneumonia caused by methicillin-resistant Staphylococcus aureus and other pathogens: report of a case successfully managed by serial surveillance cultures of endotracheal aspirates

Severe ventilator-associated pneumonia (VAP) caused by methicillin-resistant Staphylococcus aureus (MRSA) developed in a patient with acute respiratory distress syndrome. After tracheostomy, the patient was treated with antibiotic therapy guided by serial surveillance cultures of endotracheal aspirates. According to the result of the culture, the suitable antibiotic targeting the pathogen (e.g., MRSA, Pseudomonas aeruginosa, Klebsiella oxytoca) that had grown most predominantly in the culture was used until clinical resolution of VAP, leading to avoidance of overusing broad-spectrum antibiotics and ultimately a favorable outcome. During vancomycin (VCM) therapy for MRSA VAP, MRSA bacteremia occurred even though the trough value of VCM was sufficiently high. After the change from VCM to linezolid (LZD), the VAP improved promptly, indicating that LZD is superior to VCM in the treatment of MRSA pneumonia.

Comparison of the value of initial and serial endotracheal aspirate surveillance cultures in predicting the causative pathogen of ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is the most common nosocomial infection in the intensive care unit (ICU) and its outcome is affected by the adequacy and timing of initial antibiotic therapy. Recent studies have suggested that surveillance cultures of the lower airways may provide microbiological guidance for initial antibiotic prescription and increase the use of appropriate antibiotic therapy. This study aimed to compare the predictive value of initial and serial surveillance cultures of endotracheal aspirates in predicting the causative pathogen of VAP in patients receiving antibiotic therapy. This was an observational prospective cohort study. Ninety-two patients ventilated for at least 4 days were recruited into the study. Initial (IS-ETA) and serial (SS-ETA) endotracheal aspirate surveillance cultures were obtained on the day of intubation and every second day, respectively. The sensitivity, specificity, and positive and negative predictive values for the causative pathogens of VAP were calculated for each surveillance culture. Ninety-two initial and 252 serial surveillance cultures were obtained during the study period. The sensitivity of IS-ETA culture was 12% and of SS-ETA culture was 44%. The sensitivity of SS-ETA in late-onset VAP was 51%. The value of SS-ETA surveillance cultures was better than IS-ETA surveillance in predicting the causative pathogen of VAP, particularly in late-onset pneumonia.

Leukotriene D4 activates 2-integrin adhesion in human polymorphonuclear leukocytes

We examined the functional role and mechanisms by which activation of cysteinyl leukotriene-1 receptor (cysLT(1)R) regulates beta(2)-integrin adhesion to intercellular adhesion molecule (ICAM)-1 in human polymorphonuclear leukocytes (PMNs) in vitro. Human peripheral blood PMNs and eosinophils were isolated separately from the same mildly atopic donors. Surface expression of cysLT(1)R was identified both in PMNs and in eosinophils by immunofluorescence analysis. Total cysLT(1)R protein was substantially greater in eosinophils than in PMNs as determined by Western blot analysis. However, leukotriene D(4) (LTD(4)) upregulated beta(2)-integrin adhesion of PMNs to ICAM-1 with high efficacy in a time- and concentration-dependent manner. Upregulated beta(2)-integrin adhesion of PMNs was related temporally and quantitatively to phosphorylation of 85-kDa cytosolic group IVa phospholipase A2 (gIVaPLA2). Augmented LTD(4)-induced adhesion was blocked significantly by montelukast, a cysLT(1)R antagonist. Trifluoromethylketone (a gIVaPLA2 inhibitor) blocked beta(2)-integrin adhesion caused by LTD(4) activation, as did anti-CD18 monoclonal antibody directed against beta(2)-integrin on the PMN surface. Our data demonstrate that LTD(4) causes phosphorylation of gIVaPLA2 and upregulation of beta(2)-integrin adhesion to ICAM-1 or ICAM-1 surrogate through cysLT(1)R activation. Activation of gIVaPLA2 is a critical step through which beta(2)-integrin adhesion is upregulated by the cysLT(1)R expressed on the surface membrane of human PMN.

Multidrug-Resistant Gram-Negative Bacteria among Patients Who Require Chronic Hemodialysis

Multidrug-resistant gram-negative bacteria are rapidly spreading throughout the world. The epidemiology of multidrug-resistant gram-negative bacteria in patients who require chronic hemodialysis has not been previously studied. A prospective cohort study of an outpatient hemodialysis unit was conducted. Serial surveillance cultures for multidrug-resistant gram-negative bacteria, vancomycin-resistant enterococci, and methicillin-resistant Staphylococcus aureus were collected from patients who were undergoing chronic hemodialysis. Nineteen (28%) of the 67 enrolled patients were colonized with one or more antimicrobial-resistant bacteria at study enrollment. Eleven (16%), nine (13%), and three (5%) patients were colonized with multidrug-resistant gram-negative bacteria, vancomycin-resistant enterococci, and methicillin-resistant Staphylococcus aureus, respectively. Independent risk factors associated with harboring multidrug-resistant gram-negative bacteria at enrollment were residence in a long-term care facility and antibiotic exposure for > or = 7 d in the previous 3 mo. Twenty-two (40%) of 55 patients who had follow-up cultures acquired at least one antimicrobial-resistant bacterium. A total of 20, 15, and 13% of patients acquired multidrug-resistant gram-negative bacteria, vancomycin-resistant enterococci, and methicillin-resistant Staphylococcus aureus, respectively. Antibiotic exposure was the only independent risk factor for multidrug-resistant gram-negative bacteria acquisition. Endogenous multidrug-resistant gram-negative bacteria acquisition was detected among 69% of acquired multidrug-resistant gram-negative bacterial strains. The prevalence and acquisition of multidrug-resistant gram-negative bacteria surpassed that of vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus. Endogenous acquisition, as opposed to patient-to-patient spread, was the predominant mechanism of acquisition. Residence in a long-term care facility and antibiotic exposure may be important factors promoting the spread of multidrug-resistant gram-negative bacteria among this patient population.

Oral Valacyclovir as Prophylaxis against Herpes Simplex Virus Reactivation During High Dose Chemotherapy for Leukemia

Reactivation of herpes simplex virus is a common event in patients undergoing dose-intensive remission induction or consolidation chemotherapy of acute leukemia, for which either intravenous or oral acyclovir provides effective prophylaxis. This drug's short serum half-life and low oral bioavailability make frequent dosing necessary, however, and we therefore sought to determine if the pro-drug valacyclovir, which has improved bioavailability, could be successfully substituted for this indication. Eighty-one patients with leukemia were randomized to receive either 500 mg or 1,000 mg of valacyclovir orally every 8 h and followed clinically, as well as with serial surveillance cultures. Over a total of 1,979 days on study between the groups, and 380 throat cultures, no documented episodes of herpes simplex reactivation were noted. Valacyclovir was tolerated well with no evident drug-related toxicities. We conclude that valacyclovir at either of the two doses studied can be safely substituted for oral or intravenous acyclovir, and that it provides effective prophylaxis against reactivation of herpes simplex virus in this patient population.

Vancomycin-resistant enterococci in intensive care units: high frequency of stool carriage during a non-outbreak period.

We aimed to define the epidemiological associations of vancomycin-resistant enterococci (VRE) in intensive care units (ICUs) during a non-outbreak period by examining prevalence, risk factors for colonization, frequency of acquisition, and molecular strain types. A prospective cohort design was followed. Consecutive patient admissions to 2 surgical ICUs at a tertiary care hospital were enrolled. The main outcome measures were results of serial surveillance cultures screened for VRE. Of 290 patients enrolled, 35 (12%) had colonization with VRE on admission. The VRE colonization or infection had been previously detected by clinical cultures in only 4 of these patients. Using logistic regression, VRE colonization at the time of ICU admission was associated with second- and third-generation cephalosporins (odds ratio [OR] = 6.0, P<.0001), length of stay prior to surgical ICU admission (OR = 1.06, P = .001) greater than 1 prior ICU stay (OR = 9.6, P = .002), and a history of solid-organ transplantation (OR = 3.8, P = .021). Eleven (12.8%) of 78 patients with follow-up cultures acquired VRE. By pulsed-field gel electrophoresis, 2 strains predominated, one of which was associated with an overt outbreak on a non-ICU ward near the end of the study period. Colonization was common and usually not recognized by clinical culture. Most patients who had colonization with VRE and were on the surgical ICU acquired VRE prior to surgical ICU entry. Exposure to second- and third-generation cephalosporins, but not vancomycin, was an independent risk factor for colonization. Prospective surveillance of hospitalized patients may yield useful insights about the dissemination of nosocomial VRE beyond what is appreciated by clinical cultures alone.

Serial surveillance cultures of skin and catheter hub specimens from critically ill patients with central venous catheters: molecular epidemiology of infection and implications for clinical management and research.

A prospective study of 45 central venous catheters was conducted to assess, by strain delineation, the turnover of skin and catheter hub (superficial) colonization and the relative contributions of catheter hub and skin colonization to catheter tip colonization. Serial quantitative cultures of skin and catheter hub were performed. Catheter tip, blood, and specimens for culture from targeted superficial sites (TSSs) were also collected at the time of catheter removal. Strains from 17 tip-positive catheters were delineated by pulsed-field gel electrophoresis. Only 12 (28.6%) of 42 skin strains and 14 (31.1%) of 45 catheter hub strains were found to be present at the time of catheter removal. In addition, only 9 (29.0%) of the 31 tip-colonizing strains were present on TSSs. Moreover, 15 (48.4%) of the 31 tip-colonizing strains had a superficial origin, and the other 16 (51.6%) were of unknown origin. In catheters suspected of infection, cultures of TSSs had a negative predictive value for catheter-related bacteremia of 94.4% but a positive predictive value of 44.4%. When the causative agent was identified (to the strain level) these values dropped to 80.9 and 18.7%, respectively. The study shows that skin and catheter hub colonization is a common, dynamic phenomenon. Strains recovered from TSSs showed a low level of correlation with strains from previous cultures of specimens from superficial sites and catheter tip isolates. Consequently, TSSs cannot be recommended for use in determining the therapy. However, catheter-related bacteremia is uncommon when cultures of TSSs are negative.

The Epidemiology of Pseudomonas aeruginosa in Oncology Patients in a General Hospital

Pseudomonas aeruginosa colonization and infection was studied over a 6-mo period in a 36-bed mixed general medical-oncology unit. We used selective media for serial surveillance cultures on 283 patients, the environment, and personnel. Twelve percent of patients were colonized on admission and 10% acquired P. aeruginosa. Using serotyping and multilocus enzyme electrophoresis, we identified 63 genetically distinctive strains; four prevalent strains accounted for 21% of isolates. Only 5 of 33 nosocomial acquisitions were due to horizontal transmission. Nine acquisitions were linked to environmental sources (e.g., sink surfaces), which often harbored antibiotic-resistant strains but posed a risk only to oncology patients. Although significant Pseudomonas infections occurred in only 11% of colonized patients, 63% of colonized severely neutropenic patients--predominantly those who had acquired the prevalent, often environmentally linked strains--developed infections. Thus, P. aeruginosa was a significant pathogen in oncology patients; typing by multilocus enzyme electrophoresis allowed the detection of important environmental sources.

Surveillance tests for the diagnosis of invasive fungal infections in bone marrow transplant recipients.

A system for serial surveillance cultures and serological tests for diagnosis of disseminated fungal infections (FI) was evaluated retrospectively in 14 bone marrow transplantation (BMT) patients with autopsy proven FI (11 with Candida albicans and 3 with Aspergillus fumigatus) and 14 control BMT patients without FI. The 2 groups did not differ with regard to clinical features. Serial cultures for candida from various sites were more often positive in the FI group than in the controls (p less than 0.001). Consistently negative cultures were never seen in the FI patients (p less than 0.05). Positive conventional blood cultures or cultures of specimens from bronchoscopy were suggestive of FI before death in 6/14 of the patients with FI. No blood cultures were positive among the controls. Sequential serum samples taken before death in 7 patients with systemic candidiasis, 3 with invasive aspergillosis, and 12 control patients, were tested retrospectively for diagnostic candida and aspergillus antibody titers and free circulating candida mannan. The serological tests gave evidence of FI in 9/10 patients with FI and in half of the controls (p less than 0.05). In 8/10 cases with FI, serological tests became positive before a positive blood culture or a clinical suspicion of FI. With a prevalence of 7.5% of FI at our clinic, the predictive values for positive and negative was 100% and 97% for the antigenemia test and 14% and 100% for the ELISA test for IgA antibody against C. albicans mannan. Our data suggest that a rational use of surveillance cultures and serological tests may aid in an earlier diagnosis of FI in BMT patients.

Occult aminoglycoside resistance in Pseudomonas aeruginosa: epidemiology and implications for therapy and control.

The epidemiology of aminoglycoside-resistant Pseudomonas aeruginosa was evaluated in an intensive care unit (ICU) with serial surveillance cultures of throat and rectum. Bacterial population analysis performed by replica plating of primary isolation plates onto gentamicin-containing agar revealed the presence of resistant subpopulations in the initial isolates from 41 (71%) of 58 consecutive assessable patients; these isolates were stably resistant and proportionately less susceptible to other aminoglycosides. An increase in resistant subpopulations occurred during the ICU stay in 34% of 38 colonized patients cultured serially as opposed to none of 23 followed after ICU discharge (P = .0008). Isolates of P. aeruginosa from patients who received aminoglycosides in the ICU were more likely to show an increase in resistance than were isolates from other patients (55% vs. 11%; P = .005); decreasing resistance after ICU discharge followed discontinuation of antibiotic administration. ICU mortality was higher in patients with increasingly resistant subpopulations (69% vs. 16%; P = .0004). The difficulty in treating infections with P. aeruginosa and in controlling drug resistance likely relates to the common carriage of clinically undetected resistant subpopulations that emerge during therapy.