Vickie S. Baselski

Bronchoscopic diagnosis of pneumonia.

Lower respiratory tract infections are characterized by significant morbidity and mortality but also by a relative inability to establish a specific etiologic agent on clinical grounds alone. With the recognized shortcomings of expectorated or aspirated secretions toward establishing an etiologic diagnosis, clinicians have increasingly used bronchoscopy to obtain diagnostic samples. A variety of specimen types may be obtained, including bronchial washes or brushes, protected specimen brushings, bronchoalveolar lavage, and transbronchial biopsies. Bronchoscopy has been applied in three primary clinical settings, including the immunocompromised host, especially human immunodeficiency virus-infected and organ transplant patients; ventilator-associated pneumonia; and severe, nonresolving community- or hospital-acquired pneumonia in nonventilated patients. In each clinical setting, and for each specimen type, specific laboratory protocols are required to provide maximal information. These protocols should provide for the use of a variety of rapid microscopic and quantitative culture techniques and the use of a variety of specific stains and selective culture to detect unusual organism groups.

Legionella and community-acquired pneumonia: a review of current diagnostic tests from a clinician’s viewpoint

Many physicians are unaware of the limitations of the available tests for diagnosing infections with Legionella organisms. Geographic differences in the importance of nonpneumophila Legionella species as pathogens are underrecognized, in part because available diagnostic tests are biased toward the detection of pneumophila serogroup 1. Routine laboratory practices reduce the likelihood of culturing Legionella species from clinical isolates. Failure of seroconversion is common, particularly with nonpneumophila species; even when seroconversion occurs, it may take much longer than 4 weeks. Urinary antigen testing has insufficient sensitivity to affect clinical management in most regions of the United States, as it can reliably detect only L. pneumophila serogroup 1 infections. Polymerase chain reaction-based techniques offer hope of providing highly sensitive, rapid diagnostic tests for all Legionella species, but limitations in the current tests will make validating them difficult.

Chlamydia trachomatis infection in pregnancy and effect of treatment on outcome.

The effect of Chlamydia trachomatis on pregnancy outcome and the effect of treatment of positive cervical cultures was studied by culturing 11,544 women for chlamydia at their first prenatal visit. Chlamydia culture was positive in 2433 (21.08%) and prevalence was related to age and race. Of the positive cultures, 1110 were classified as untreated. The untreated group demonstrated a significant increase in the incidence of premature rupture of the membranes and low birth weight and a decrease in survival when compared with either those with positive cultures who received treatment (N = 1323) or those with negative cultures (N = 9111). Screening of populations at high risk of chlamydia is recommended and treatment of chlamydia-positive patients may improve pregnancy outcome.

Effectiveness of Preanalytic Practices on Contamination and Diagnostic Accuracy of Urine Cultures: a Laboratory Medicine Best Practices Systematic Review and Meta-analysis

SUMMARY Background. Urinary tract infection (UTI) in the United States is the most common bacterial infection, and urine cultures often make up the largest portion of workload for a hospital-based microbiology laboratory. Appropriately managing the factors affecting the preanalytic phase of urine culture contributes significantly to the generation of meaningful culture results that ultimately affect patient diagnosis and management. Urine culture contamination can be reduced with proper techniques for urine collection, preservation, storage, and transport, the major factors affecting the preanalytic phase of urine culture. Objectives. The purposes of this review were to identify and evaluate preanalytic practices associated with urine specimens and to assess their impact on the accuracy of urine culture microbiology. Specific practices included collection methods for men, women, and children; preservation of urine samples in boric acid solutions; and the effect of refrigeration on stored urine. Practice efficacy and effectiveness were measured by two parameters: reduction of urine culture contamination and increased accuracy of patient diagnosis. The CDC Laboratory Medicine Best Practices (LMBP) initiatives systematic review method for assessment of quality improvement (QI) practices was employed. Results were then translated into evidence-based practice guidelines. Search strategy. A search of three electronic bibliographic databases (PubMed, SCOPUS, and CINAHL), as well as hand searching of bibliographies from relevant information sources, for English-language articles published between 1965 and 2014 was conducted. Selection criteria. The search contained the following medical subject headings and key text words: urinary tract infections, UTI, urine/analysis, urine/microbiology, urinalysis, specimen handling, preservation, biological, preservation, boric acid, boric acid/borate, refrigeration, storage, time factors, transportation, transport time, time delay, time factor, timing, urine specimen collection, catheters, indwelling, urinary reservoirs, continent, urinary catheterization, intermittent urethral catheterization, clean voided, midstream, Foley, suprapubic, bacteriological techniques, and microbiological techniques. Main results. Both boric acid and refrigeration adequately preserved urine specimens prior to their processing for up to 24 h. Urine held at room temperature for more than 4 h showed overgrowth of both clinically significant and contaminating microorganisms. The overall strength of this body of evidence, however, was rated as low. For urine specimens collected from women, there was no difference in rates of contamination for midstream urine specimens collected with or without cleansing. The overall strength of this evidence was rated as high. The levels of diagnostic accuracy of midstream urine collection with or without cleansing were similar, although the overall strength of this evidence was rated as low. For urine specimens collected from men, there was a reduction in contamination in favor of midstream clean-catch over first-void specimen collection. The strength of this evidence was rated as high. Only one study compared midstream collection with cleansing to midstream collection without cleansing. Results showed no difference in contamination between the two methods of collection. However, imprecision was due largely to the small event size. The diagnostic accuracy of midstream urine collection from men compared to straight catheterization or suprapubic aspiration was high. However, the overall strength of this body of evidence was rated as low. For urine specimens collected from children and infants, the evidence comparing contamination rates for midstream urine collection with cleansing, midstream collection without cleansing, sterile urine bag collection, and diaper collection pointed to larger reductions in the odds of contamination in favor of midstream collection with cleansing over the other methods of collection. This body of evidence was rated as high. The accuracy of diagnosis of urinary tract infection from midstream clean-catch urine specimens, sterile urine bag specimens, or diaper specimens compared to straight catheterization or suprapubic aspiration was varied. Authors conclusions. No recommendation for or against is made for delayed processing of urine stored at room temperature, refrigerated, or preserved in boric acid. This does not preclude the use of refrigeration or chemical preservatives in clinical practice. It does indicate, however, that more systematic studies evaluating the utility of these measures are needed. If noninvasive collection is being considered for women, midstream collection with cleansing is recommended, but no recommendation for or against is made for midstream collection without cleansing. If noninvasive collection is being considered for men, midstream collection with cleansing is recommended and collection of first-void urine is not recommended. No recommendation for or against is made for collection of midstream urine without cleansing. If noninvasive collection is being considered for children, midstream collection with cleansing is recommended and collection in sterile urine bags, from diapers, or midstream without cleansing is not recommended. Whether midstream collection with cleansing can be routinely used in place of catheterization or suprapubic aspiration is unclear. The data suggest that midstream collection with cleansing is accurate for the diagnosis of urinary tract infections in infants and children and has higher average accuracy than sterile urine bag collection (data for diaper collection were lacking); however, the overall strength of evidence was low, as multivariate modeling could not be performed, and thus no recommendation for or against can be made.

Acute Postoperative Respiratory Failure Caused by Chlamydia Pneumoniae and Diagnosed by Bronchoalveolar Lavage

Most Chlamydia pneumoniae infections are mild, but 10% develop into pneumonia. C. pneumoniae has been observed in hospital in intubated patients undergoing major surgery or admitted with severe trauma. A patient with squamous cell carcinoma in whom severe pneumonia developed postpneumonectomy and who required mechanical ventilation is presented. The patient was initially treated for nosocomial bacterial pneumonia with the broad spectrum antibiotics ceftazidime, amikacin, and vancomycin. The patient underwent a bronchoalveolar lavage, from which C. pneumoniae was grown. Generally, these patients are a high-risk mortality group. Only after substituting the above antibiotics with doxycycline, to which C. pneumoniae was sensitive, did the pneumonia respond. Whether this was a nosocomial or a community-acquired pneumonia is uncertain.

Point-Counterpoint: Quantitative Cultures of Bronchoscopically Obtained Specimens Should Be Performed for Optimal Management of Ventilator-Associated Pneumonia

ABSTRACT Ventilator-associated pneumonia (VAP) is a leading cause of health care-associated infection. It has a high rate of attributed mortality, and this mortality is increased in patients who do not receive appropriate empirical antimicrobial therapy. As a result of the overuse of broad-spectrum antimicrobials such as the carbapenems, strains of Acinetobacter, Enterobacteriaceae, and Pseudomonas aeruginosa susceptible only to polymyxins and tigecycline have emerged as important causes of VAP. The need to accurately diagnose VAP so that appropriate discontinuation or de-escalation of antimicrobial therapy can be initiated to reduce this antimicrobial pressure is essential. Practice guidelines for the diagnosis of VAP advocate the use of bronchoalveolar lavage (BAL) fluid obtained either bronchoscopically or by the use of a catheter passed through the endotracheal tube. The CDC recommends that quantitative cultures be performed on these specimens, using ≥104 CFU/ml to designate a positive culture (http://www.cdc.gov/nhsn/TOC_PSCManual.html, accessed 30 October 2012). However, there is no consensus in the clinical microbiology community as to whether these specimens should be cultured quantitatively, using the aforementioned designated bacterial cell count to designate infection, or by a semiquantitative approach. We have asked Vickie Baselski, University of Tennessee Health Science Center, who was the lead author on one of the seminal papers on quantitative BAL fluid culture, to explain why she believes that quantitative BAL fluid cultures are the optimal strategy for VAP diagnosis. We have Stacey Klutts, University of Iowa, to advocate the semiquantitative approach.

Fatal Prototheca wickerhamii Bloodstream Infection in a Cardiac Allograft Recipient

We read with great interest the recent comprehensive review by McMullan et al. concerning the potential pitfalls involved in diagnosis of algaemia due to Prototheca species presented as a report of an elderly cardiac transplant recipient who had a fatal case of protothecosis ([1][1]). We found the

Quantitative cultures of bronchoscopically obtained specimens should be performed for optimal management of ventilator-associated pneumonia.

ABSTRACT Ventilator-associated pneumonia (VAP) is a leading cause of health care-associated infection. It has a high rate of attributed mortality, and this mortality is increased in patients who do not receive appropriate empirical antimicrobial therapy. As a result of the overuse of broad-spectrum antimicrobials such as the carbapenems, strains of Acinetobacter, Enterobacteriaceae, and Pseudomonas aeruginosa susceptible only to polymyxins and tigecycline have emerged as important causes of VAP. The need to accurately diagnose VAP so that appropriate discontinuation or de-escalation of antimicrobial therapy can be initiated to reduce this antimicrobial pressure is essential. Practice guidelines for the diagnosis of VAP advocate the use of bronchoalveolar lavage (BAL) fluid obtained either bronchoscopically or by the use of a catheter passed through the endotracheal tube. The CDC recommends that quantitative cultures be performed on these specimens, using ≥104 CFU/ml to designate a positive culture (http://www.cdc.gov/nhsn/TOC_PSCManual.html, accessed 30 October 2012). However, there is no consensus in the clinical microbiology community as to whether these specimens should be cultured quantitatively, using the aforementioned designated bacterial cell count to designate infection, or by a semiquantitative approach. We have asked Vickie Baselski, University of Tennessee Health Science Center, who was the lead author on one of the seminal papers on quantitative BAL fluid culture, to explain why she believes that quantitative BAL fluid cultures are the optimal strategy for VAP diagnosis. We have Stacey Klutts, University of Iowa, to advocate the semiquantitative approach.

The Standardization of Criteria for Processing and Interpreting Laboratory Specimens in Patients With Suspected Ventilator-Associated Pneumonia

The microbiologic analysis of respiratory specimens is a key component of both the clinical investigation of ventilator-associated pneumonia (VAP) and patient care. Although there is a substantial body of literature on the use of a variety of lower respiratory tract specimens, there is little standardization of the approaches to processing and interpreting results from the various specimens. The purpose of this communication is to delineate specific recommendations for the microbiologic analysis of specimens originating from the lower respiratory tract, as developed by the Laboratory Analysis Group of the Consensus Conference.

Point-Counterpoint: Quantitative cultures of bronchoscopically obtained specimens should be performed for optimal management in patients with ventilator associated pneumonia.

ABSTRACT Ventilator-associated pneumonia (VAP) is a leading cause of health care-associated infection. It has a high rate of attributed mortality, and this mortality is increased in patients who do not receive appropriate empirical antimicrobial therapy. As a result of the overuse of broad-spectrum antimicrobials such as the carbapenems, strains of Acinetobacter, Enterobacteriaceae, and Pseudomonas aeruginosa susceptible only to polymyxins and tigecycline have emerged as important causes of VAP. The need to accurately diagnose VAP so that appropriate discontinuation or de-escalation of antimicrobial therapy can be initiated to reduce this antimicrobial pressure is essential. Practice guidelines for the diagnosis of VAP advocate the use of bronchoalveolar lavage (BAL) fluid obtained either bronchoscopically or by the use of a catheter passed through the endotracheal tube. The CDC recommends that quantitative cultures be performed on these specimens, using ≥104 CFU/ml to designate a positive culture (http://www.cdc.gov/nhsn/TOC_PSCManual.html, accessed 30 October 2012). However, there is no consensus in the clinical microbiology community as to whether these specimens should be cultured quantitatively, using the aforementioned designated bacterial cell count to designate infection, or by a semiquantitative approach. We have asked Vickie Baselski, University of Tennessee Health Science Center, who was the lead author on one of the seminal papers on quantitative BAL fluid culture, to explain why she believes that quantitative BAL fluid cultures are the optimal strategy for VAP diagnosis. We have Stacey Klutts, University of Iowa, to advocate the semiquantitative approach.