First Trimester Ultrasound and Aneuploidy Screening in Twins

All patients with twin pregnancy should have first trimester ultrasound and be offered screening for chromosomal aneuploidy as well as diagnostic testing. Screening for aneuploidy in twins presents unique challenges compared with singletons. Cell-free DNA screening should be considered first-line; however, this option may not be available or may have limitations in certain clinical scenarios, such as vanishing twins. If cell-free DNA screening is not available, maternal serum marker screening in conjunction with nuchal translucency assessment should be offered. Patients with positive aneuploidy screening tests or fetal structural abnormalities should be offered diagnostic testing.

Standard-Dose Azithromycin in Class III Obese Patients Undergoing Unscheduled Cesarean Delivery

OBJECTIVE

 Perioperative antibiotic prophylaxis reduces cesarean wound complications. This study investigates whether integration of standard-dose (500 mg) azithromycin prophylaxis reduced wound complications in patients with class III obesity (body mass index [BMI] ≥ 40 kg/m2) undergoing unscheduled cesarean delivery.

STUDY DESIGN

 Retrospective cohort study of patients with class III obesity undergoing unscheduled cesarean delivery in single hospital system from January 1, 2017, to January 1, 2020. A standard dose (500 mg) of azithromycin was integrated into system order sets in 2018. Medical history and postoperative wound outcomes were compared in pre- and postintegration cohorts. Wound complication was defined as composite of wound seroma, hematoma, superficial or deep infection.

RESULTS

 A total of 1,273 patients met inclusion criteria, 303 patients in the preorder set group, and 970 patients in the postorder set group. Demographics were similar between the pre- and postintegration cohorts, including BMI (median: 44.4 kg/m2, p = 0.84) and weight at delivery (mean: 121.2 ± 17.8 kg, p = 0.57). Patients in the postintegration cohort had lower rates of composite postpartum wound complication (7.9 vs. 13.9%, p = 0.002), superficial infection or deep infection/abscess (6.7 vs. 10.2%, p = 0.042), and postpartum readmission or unscheduled visits (18.7 vs. 24.4%, p < 0.029). Rates of chorioamnionitis and endometritis were similar between the pre- and postintegration groups (8.6 vs. 6.9%, p = 0.33, and 1.7 vs. 1.9%, p = 0.81, respectively). Patients in the postintegration cohort had lower risk of postoperative composite wound complication (unadjusted odds ratio [OR]: 0.54, confidence interval [CI]: 0.36-0.80, p = 0.002) and lower rates of wound infection (unadjusted OR: 0.63, 95% CI: 0.40-0.99, p = 0.044). When comparing patients who received azithromycin at delivery and patients who did not, standard-dose azithromycin reduced risk of postoperative wound complication (unadjusted OR: 0.67, 95% CI: 0.46-0.99, p = 0.043).

CONCLUSION

 A standard dose of azithromycin provides adequate perioperative prophylaxis in class III obese patients, decreasing rates of postcesarean wound complications and unscheduled postpartum outpatient visits.

KEY POINTS

· Class III obese patients undergoing unscheduled cesarean have high rates of wound complications.. · Standard-dose azithromycin reduces risk of postcesarean wound infection in class III obese patients.. · Standard-dose azithromycin reduces readmission, unscheduled visits in class III obese patients..

The Evolving Landscape of Genetic Carrier Screening: Clinical Considerations and Challenges

Importance

Genetic carrier screening is performed to identify carriers of rare genetic diseases. Identification of carriers allows patients to make informed reproductive health choices and can decrease the incidence of genetic disorders with serious medical implications.

Objective

This review aims to provide an overview of the history of prenatal genetic screening and the various forms of carrier screening, a synopsis of recent changes in society recommendations and current practice guidelines, and discussion of clinical challenges associated with carrier screening.

Evidence Acquisition

Published practice guidelines from relevant professional societies were reviewed and synthesized. PubMed search was performed for relevant history and clinical considerations of carrier screening.

Results

Information and evidence summarized in this review include professional society practice guidelines, review articles, and peer-reviewed research articles.

Conclusions and Relevance

Current practice guidelines differ between stakeholder professional organizations. Expanded carrier screening offers increased identification of rare disease carriers allowing for more informed reproductive choices. However, there are several barriers to the implementation of expanded carrier screening for all patients.

Labor and Delivery Outcomes with the Sequential Use of Misoprostol Followed by Cervical Foley Catheter

OBJECTIVE

Studies demonstrate shorter time to delivery with concurrent use of misoprostol and cervical Foley catheter. However, concurrent placement may not be feasible. If misoprostol is used to start an induction, little is known regarding the benefit of sequentially using Foley catheter. We examine obstetrical outcomes in women with Foley catheter placed after misoprostol compared with those only requiring misoprostol.

STUDY DESIGN

Retrospective cohort study of singleton pregnancies, intact membranes, and an unfavorable cervix (Bishop score of ≤6 and dilation ≤2 cm) undergoing term induction May 2013 to June 2015. We compared obstetrical outcomes between women receiving misoprostol alone versus those that had a Foley catheter placed after misoprostol. Outcomes are mode of delivery, time to delivery, chorioamnionitis, admission to neonatal intensive care unit, and maternal morbidity. Chi-square and Fisher's exact tests were used for categorical variables, Mann-Whitney U-tests compared continuous variables.

RESULTS

Among 364 women, 281 began induction with misoprostol alone. A total of 135 (48%) subsequently had a Foley catheter placed. Characteristics were similar between the groups, although nulliparity and cervical dilation <1 cm at start of induction were more likely to have subsequent Foley catheter. Women with Foley catheter placement after misoprostol had a longer median time to delivery (15 vs. 11 hours, p < 0.001), twofold higher rate of cesarean (42 vs. 26%, odds ratio: 2.1, 95% confidence interval: 1.26-3.44, p = 0.004), and increased risk of neonatal intensive care unit (NICU) admission (21 vs. 11%, p = 0.024). There was a nonsignificant increased risk of chorioamnionitis (12 vs. 7%, p = 0.1) and maternal morbidity (15 vs. 8%, p = 0.08) in the misoprostol followed by Foley catheter group.

CONCLUSION

In women receiving misoprostol for induction, nulliparas and those with dilation <1 cm are more likely to have subsequent Foley catheter placement. Sequential use of cervical Foley catheter after misoprostol is associated with longer labor, higher cesarean rate, and increased NICU admission. Requirement of Foley catheter after misoprostol confers higher risk and may guide counseling.

KEY POINTS

· Little is known regarding efficacy of misoprostol followed by cervical Foley catheter.. · Nulliparas and dilation <1 cm increases need for Foley after misoprostol.. · Complications were more common in women requiring Foley after misoprostol..

Screening Echocardiogram in High-Risk Women with Class III Obesity to Predict the Risk of Preeclampsia

OBJECTIVE

Women with obesity and other comorbidities such as hypertension and diabetes are at an increased risk of preeclampsia and perinatal morbidity. This study evaluates whether screening echocardiogram can identify women with obesity at a higher risk of preeclampsia.

METHODS

We conducted a retrospective cohort study of women with class III obesity (body mass index [BMI] ≥40 kg/m²) and one or more medical comorbidities associated with an increased risk of preeclampsia (such as diabetes, hypertension, and rheumatologic disease) undergoing screening echocardiogram. Abnormal findings were defined as the presence of one or more of the following: diastolic dysfunction, ejection fraction of ≤45%, or cardiac chamber enlargement or hypertrophy. Multivariable logistic regression was used to estimate the odds ratio (OR) of gestational hypertension/mild preeclampsia, severe preeclampsia, and any preterm delivery <37 weeks associated with abnormal echocardiographic findings when controlling for potential confounders.

RESULTS

Of 267 eligible women, 174 (64%) underwent screening echocardiograms. Sixty-nine women (40%) had abnormal echocardiograms. Maternal clinical characteristics were similar between women with normal echocardiographic findings and women with abnormal findings. Women with abnormal echocardiograms were more likely to have chronic hypertension (78 vs. 62%, p = 0.04) and a history of preeclampsia (27 vs. 10%, p = 0.02). After controlling for confounders, women with abnormal echocardiogram were at an increased risk of hypertensive disorders of pregnancy, OR 6.80 (95% confidence interval [CI] 3.32-13.93, p = 0.01), and in particular severe preeclampsia, OR 8.77 (95% CI 3.90-19.74, p = 0.01).

CONCLUSION

Among pregnant women with class III obesity and medical comorbidities, screening echocardiogram may help identify a subset of women at the highest risk of developing preeclampsia.

KEY POINTS

· Women with obesity and comorbid conditions are at a high risk of abnormal echocardiogram.. · Women with obesity, medical comorbid conditions, and abnormal echo are at a high risk of preeclampsia.. · Screening echocardiogram can help identify obese women at the highest risk of severe preeclampsia..

Screening for aneuploidy in twins

All pregnant women should be offered screening for aneuploidy. Twin pregnancies present unique challenges in aneuploidy screening. This review describes available aneuploidy screening options and their benefits and limitations in twin pregnancy, along with describing special circumstances, such as vanishing twins and diagnostic testing in twin pregnancy. No method of aneuploidy screening is as accurate in twin pregnancies as singleton pregnancies. Cell-free DNA screening should be considered a first-line approach; however, this option may not be available or may have limitations in certain clinical scenarios, such as vanishing twins. If cell-free DNA screening is not available, nuchal translucency and/or maternal serum marker screening can be offered.

Obesity and no call results: optimal timing of cell-free DNA testing and redraw

BACKGROUND

Fetal fraction of cell-free DNA decreases with increasing maternal weight. Consequently, cell-free DNA screening for fetal aneuploidy has higher screen failures or "no call" rates in women with obesity owing to a low fetal fraction. The optimal timing of testing based on maternal weight is unknown.

OBJECTIVE

This study aimed to identify the optimal timing of initial cell-free DNA testing based on maternal weight and to identify the optimal timing of repeat cell-free DNA testing in cases with an initial screen failure.

STUDY DESIGN

This was a retrospective cohort study of women undergoing cell-free DNA for fetal aneuploidy screening between 9 and 18 weeks through a single laboratory over 1 year from 2018 to 2019. Fetal fraction change per week was calculated, and generalized linear models were used to calculate relative risk and 95% confidence interval of a no call result at given maternal weights and gestational ages.

RESULTS

The vast majority of samples (99.22%) received a test result. The risk of a no call result owing to a low fetal fraction was higher with increasing maternal weight. At 9 to 12 weeks, the rate of a no call result owing to a low fetal fraction in women who weighed <150 lb was 0.14% compared with 17.39% in women weighing >400 lb. Fetal fraction increased with increasing gestational age, although the incremental increase in fetal fraction over time is inversely proportional to maternal weight. At 13 to 18 weeks' gestation, 6.45% of women weighing >400 lb received a no call result owing to a low fetal fraction. In women in the highest weight category, >400 lb, fetal fraction increased 0.5% with each week of gestation.

CONCLUSION

Although the risk of a no call result increases with maternal weight, cell-free DNA screening should be offered to all women at 9 to 12 weeks' gestation, allowing the option to have chorionic villus sampling after a positive test result. Pretest counseling for women with obesity should include the increased chance for a test failure. Most women weighing less than 400 lb will receive a test result and more than 80% of women with a weight of >400 lb will receive a test result at 9 to 12 weeks' gestation. Data regarding the expected increase in cell-free DNA fetal fraction per week may help guide the timing of a redraw to optimize test success.

Exome Sequencing and Its Emerging Role in Prenatal Genetic Diagnosis

Importance

Prenatal genetic diagnosis can guide pregnancy management and decision making. Genetic diagnosis has advanced rapidly, and chromosomal microarray has become widely used, in addition to conventional karyotype. Exome sequencing may provide an even higher detection rate of genetic anomalies and may be more commonly applied in the future.

Objectives

The objectives of this manuscript are to review current practices in prenatal genetic diagnosis, define exome sequencing, identify scenarios in which exome sequencing may be indicated, identify potential concerns regarding exome sequencing, and review the importance for the general obstetrician-gynecologist to understand exome sequencing technology and its uses.

Evidence Acquisition

A MEDLINE search of "prenatal genetic testing," "chromosomal microarray," "conventional karyotype," or "exome sequencing" in the review was performed.

Results

The evidence cited in this review includes 6 medical society committee opinions and 17 additional peer-reviewed journal articles that were original research or expert opinion summaries.

Conclusions and Relevance

Exome sequencing may be a useful prenatal genetic diagnostic tool in cases with ultrasound anomalies with previously normal chromosomal microarray and/or karyotype. As more data become available, technology improves, and costs fall, exome sequencing may become more widely used in prenatal genetic diagnosis.

Association between cell-free DNA fetal fraction and gestational diabetes

OBJECTIVE

To determine the association between cell-free DNA (cfDNA) fetal fraction and gestational diabetes (GDM) in a cohort of women presenting for cfDNA screening for fetal aneuploidy.

METHODS

A retrospective cohort study of women with singleton pregnancies who had cfDNA screening at a single institution at 10 to 20 weeks gestation between October 2011 and October 2017. Fetal fractions were adjusted for gestational age (GA) using multiples of the median (MoM). Multivariable logistic regression was used to estimate the odds ratio (OR) of GDM controlling for potential confounders.

RESULTS

Two thousand six hundred twenty-three pregnancies met criteria. Women with GDM had a lower fetal fraction (0.93 MoM vs. 1.05 MoM, P = .002). However, the association between fetal fraction and GDM was not significant after adjusting for body mass index (BMI) [OR 0.84, 95% confidence interval (CI) 0.52-1.36; P = .48]. Since insulin resistance increases at later GAs, separate analysis on women with GA 14 to 20 weeks was performed. Again, the association between fetal fraction and GDM was not significant after adjusting for BMI, (OR 0.81, 95% CI 0.31-2.12; P = .67).

CONCLUSION

Low or high fetal fraction of cfDNA was not associated with GDM. Although fetal fraction was lower among women diagnosed with GDM, this relationship was no longer statistically significant once maternal BMI was taken into account.

Cell-free DNA for Down syndrome screening in obese women: Is it a cost-effective strategy?

OBJECTIVE

Determine cost differences between cell-free DNA (cfDNA) and serum integrated screening (INT) in obese women given the limitations of aneuploidy screening in this population.

METHODS

Using a decision-analytic model, we estimated the cost-effectiveness of trisomy 21 screening in class III obese women using cfDNA compared with INT. Primary outcomes of the model were cost, number of unnecessary invasive tests, procedure-related fetal losses, and missed cases of trisomy 21.

RESULTS

In base case, the mean cost of cfDNA was $498 greater than INT ($1399 vs $901). cfDNA resulted in lower probabilities of unnecessary invasive testing (2.9% vs 3.5%), procedure-related loss (0.015% vs 0.019%), and missed cases of T21 (0.00013% vs 0.02%). cfDNA cost $87 485 per unnecessary invasive test avoided, $11 million per procedure-related fetal loss avoided, and $2.2 million per missed case of T21 avoided. In sensitivity analysis, when the probability of insufficient fetal fraction is assumed to be >25%, cfDNA is both costlier than INT and results in more unnecessary invasive testing (a dominated strategy).

CONCLUSION

When the probability of insufficient fetal fraction more than 25% (a maternal weight of ≥300 lbs), cfDNA is costlier and results in more unnecessary invasive testing than INT.

Are prediction models for vaginal birth after cesarean accurate?

BACKGROUND

The use of trial of labor after cesarean delivery calculators in the prediction of successful vaginal birth after cesarean delivery gives physicians an evidence-based tool to assist with patient counseling and risk stratification. Before deployment of prediction models for routine care at an institutional level, it is recommended to test their performance initially in the institution's target population. This allows the institution to understand not only the overall accuracy of the model for the intended population but also to comprehend where the accuracy of the model is most limited when predicting across the range of predictions (calibration).

OBJECTIVE

The purpose of this study was to compare 3 models that predict successful vaginal birth after cesarean delivery with the use of a single tertiary referral cohort before continuous model deployment in the electronic medical record.

STUDY DESIGN

All cesarean births for failed trial of labor after cesarean delivery and successful vaginal birth after cesarean delivery at an academic health system between May 2013 and March 2016 were reviewed. Women with a history of 1 previous cesarean birth who underwent a trial of labor with a term (≥37 weeks gestation), cephalic, and singleton gestation were included. Women with antepartum intrauterine fetal death or fetal anomalies were excluded. The probability of successful vaginal birth after cesarean delivery was calculated with the use of 3 prediction models: Grobman 2007, Grobman 2009, and Metz 2013 and compared with actual vaginal birth after cesarean delivery success. Each model's performance was measured with the use of concordance indices, Brier scores, and calibration plots. Decision curve analysis identified the range of threshold probabilities for which the best prediction model would be of clinical value.

RESULTS

Four hundred four women met the eligibility criteria. The observed rate of successful vaginal birth after cesarean delivery was 75% (305/404). Concordance indices were 0.717 (95% confidence interval, 0.659-0.778), 0.703 (95% confidence interval, 0.647-0.758), and 0.727 (95% confidence interval, 0.669-0.779), respectively. Brier scores were 0.172, 0.205, and 0.179, respectively. Calibration demonstrated that Grobman 2007 and Metz vaginal birth after cesarean delivery models were most accurate when predicted probabilities were >60% and were beneficial for counseling women who did not desire to have vaginal birth after cesarean delivery but had a predicted success rates of 60-90%. The models underpredicted actual probabilities when predicting success at <60%. The Grobman 2007 and Metz vaginal birth after cesarean delivery models provided greatest net benefit between threshold probabilities of 60-90% but did not provide a net benefit with lower predicted probabilities of success compared with a strategy of recommending vaginal birth after cesarean delivery for all women .

CONCLUSION

When 3 commonly used vaginal birth after cesarean delivery prediction models are compared in the same population, there are differences in performance that may affect an institution's choice of which model to use.

Efficacy of Non-Beta-lactam Antibiotics for Prevention of Cesarean Delivery Surgical Site Infections

Objective  To examine the association between perioperative Beta ( β ))-lactam versus non- β -lactam antibiotics and cesarean delivery surgical site infection (SSI). Study Design  Retrospective cohort of women undergoing cesarean delivery from January 1 to December 31, 2014. All women undergoing cesarean after 34 weeks with a postpartum visit were included. Prevalence of SSI was compared between women receiving β -lactam versus non- β -lactam antibiotics. Bivariate analyses were performed using Pearson's Chi-square, Fisher's exact, or Wilcoxon's rank-sum tests. Logistic regression models were fit controlling for possible confounders. Results  Of the 929 women included, 826 (89%) received β -lactam prophylaxis and 103 (11%) received a non- β -lactam. Among the 893 women who reported a non-type I (low risk) allergy, 819 (92%) received β -lactam prophylaxis. SSI occurred in 7% of women who received β -lactam antibiotics versus 15% of women who received a non- β -lactam ( p  = 0.004). β -Lactam prophylaxis was associated with lower odds of SSI compared with non- β -lactam antibiotics (odds ratio [OR] = 0.43; 95% confidence interval [CI] = 0.22-0.83; p  = 0.01) after controlling for chorioamnionitis in labor, postlabor cesarean, endometritis, tobacco use, and body mass index (BMI). Conclusion   β -Lactam perioperative prophylaxis is associated with lower odds of a cesarean delivery surgical site infection compared with non- β -lactam antibiotics.

Induction of Labor versus Scheduled Cesarean in Morbidly Obese Women: A Cost-Effectiveness Analysis

OBJECTIVE

To assess the costs, complication rates, and harm-benefit tradeoffs of induction of labor (IOL) compared to scheduled cesarean delivery (CD) in women with class III obesity.

STUDY DESIGN

We conducted a cost analysis of IOL versus scheduled CD in nulliparous morbidly obese women. Primary outcomes were surgical site infection (SSI), chorioamnionitis, venous thromboembolism, blood transfusion, and readmission. Model outcomes were mean cost of each strategy, cost per complication avoided, and complication tradeoffs. We assessed the costs, complication rates, and harm-benefit tradeoffs of IOL compared with scheduled CD in women with class III obesity.

RESULTS

A total of 110 patients underwent scheduled CD and 114 underwent IOL, of whom 61 (54%) delivered via cesarean. The group delivering vaginally experienced fewer complications. SSI occurred in 0% in the vaginal delivery group, 13% following scheduled cesarean, and 16% following induction then cesarean. In the decision model, the mean cost of induction was $13,349 compared with $14,575 for scheduled CD. Scheduled CD costs $9,699 per case of chorioamnionitis avoided, resulted in 18 cases of chorioamnionitis avoided per additional SSI and 3 cases of chorioamnionitis avoided per additional hospital readmission. In sensitivity analysis, IOL is cost saving compared with scheduled CD unless the cesarean rate following induction exceeds 70%.

CONCLUSION

In morbidly obese women, induction of labor remains cost-saving until the rate of cesarean following induction exceeds 70%.

Perioperative Antibiotic Choice in Labored versus Unlabored Cesareans and Risk of Postcesarean Infectious Morbidity

OBJECTIVE

 This study aims to estimate postcesarean infectious morbidity in women receiving perioperative β-lactam versus non-β-lactam antibiotics.

METHODS

 We conducted a retrospective cohort analysis of the Maternal-Fetal Medicine Unit Cesarean Registry. The exposure was β-lactam perioperative antibiotics versus non-β-lactam regimens at cesarean delivery (CD). We stratified by labored versus unlabored CD. The primary composite outcome included wound infection, seroma, hematoma, endometritis, readmission due to wound complication, or debridement. Multivariable logistic regression estimated odds of wound complication by antibiotic regimen after adjusting for relevant confounders.

RESULTS

 Our analysis included 43,735 women who delivered via CD, 48% following labor. In both groups, 95% of women received β-lactam antibiotics. In the labored CD group (n = 20,860), there was no significant difference in primary outcome by β-lactam versus non-β-lactam antibiotics (10.5 vs. 9.9%, p = 0.53). In the unlabored CD group (n = 22,875), women receiving non-β-lactam antibiotics were more likely to experience a wound complication compared with those in the β-lactam group (6.2 vs. 4.7%, p = 0.02, adjusted odds ratio: 1.39, 95% confidence interval: 1.08-1.80) after adjustment for clinical confounders.

CONCLUSION

 In unlabored CD, non-β-lactam antibiotics have a higher risk of wound complications compared with β-lactam regimens. Further study to optimize antibiotic prophylaxis for β-lactam allergic women undergoing unlabored CD is warranted.

Hepatoid carcinoma of the ovary: A case report and review of the literature

Primary hepatoid carcinoma of the ovary (HCO) is a rare aggressive tumor that typically presents at an advanced stage in postmenopausal women with unilateral or bilateral ovarian masses and elevated AFP and CA125. We report a case of HCO in a 73 year-old woman who presented with abdominal distention, weight loss, and a large lower abdominal mass. Postoperative serum AFP was markedly elevated and trended down with initiation of chemotherapy. Review of the literature revealed thirty-two reported cases with no consensus on histogenesis or consistent immunohistochemical profile other than positive AFP staining in all but one case. Although the optimal treatment has not yet been determined, tumor debulking surgery followed by a platinum and taxane based chemotherapy regimen has shown promise. Both serum AFP and CA125 appear to have prognostic value and can be used to follow response to treatment and screen for recurrence.

Endogenous microbial contamination of cultured autologous preparations in trials of cancer immunotherapy

BACKGROUND

Standardization of the manufacturing and processing of cellular immunotherapy products is necessary to ensure patient safety, establish efficacy, and demonstrate potency. Recognition of the autologous donor as a likely source of microbial contamination of cellular immunotherapy products may improve patient care and reduce expense to the laboratory.

METHODS

Data on 243 immunotherapy products manufactured in the authors' institution between December 1997 and June 2001 were retrospectively reviewed. Also reviewed were the case reports of four patients whose autologous immunotherapy products were contaminated.

RESULTS

Twenty-five (10%) of the 243 immunotherapy products processed were positive on one or more tests for microbial contamination. In six (24%) of the products, the source of microbial contamination was the autologous donor. In 17 of the remaining 19 products, test results were judged to be false-positive.

DISCUSSION

The unique processing techniques and stringent controls involved in the manufacture of cellular immunotherapy products may result in changes in the sources of microbial contamination routinely encountered. The identification of the autologous donor as a potential source of the microbial contamination of the product may assist the clinician and the laboratory in troubleshooting products with positive results on microbial sterility testing. Also, the number of false-positive results in this study indicates that further research is needed to maximize the specificity of testing while maintaining the present high sensitivity.

Direct detection of Legionella species from bronchoalveolar lavage and open lung biopsy specimens: comparison of LightCycler PCR, in situ hybridization, direct fluorescence antigen detection, and culture

We developed a rapid thermocycling, real-time detection (also known as real-time PCR) method for the detection of Legionella species directly from clinical specimens. This method uses the LightCycler (Roche Molecular Biochemicals, Indianapolis, Ind.) and requires approximately 1 to 2 h to perform. Both a Legionella genus PCR assay and Legionella pneumophila species-specific PCR assay were designed. A total of 43 archived specimens from 35 patients were evaluated, including 19 bronchoalveolar lavage (BAL) specimens and 24 formalin-fixed, paraffin-embedded open lung biopsy specimens. Twenty-five of the specimens were culture-positive for Legionella (9 BAL specimens and 16 tissue specimens). BAL specimens were tested by LightCycler PCR (LC-PCR) methods and by a direct fluorescent antibody (DFA) assay, which detects L. pneumophila serogroups 1 to 6 and several other Legionella species. Tissue sections were tested by the two LC-PCR methods, by DFA, by an in situ hybridization (ISH) assay, specifically designed to detect L. pneumophila, and by Warthin-Starry (WS) staining. The results were compared to the "gold standard" method of bacterial culture. With BAL specimens the following assays yielded the indicated sensitivities and specificities, respectively: Legionella genus detection by Legionella genus LC-PCR, 100 and 100%; Legionella genus detection by DFA assay, 33 and 100%; and L. pneumophila detection by L. pneumophila species-specific LC-PCR, 100 and 100%. With open lung biopsy specimens the following assays yielded the indicated sensitivities and specificities, respectively: Legionella genus detection by LC-PCR 68.8 and 100%; Legionella genus detection by DFA assay, 44 and 100%; Legionella genus detection by WS staining, 63 and 100%; L. pneumophila species-specific detection by LC-PCR, 17 and 100%; and L. pneumophila species-specific detection by ISH, 100 and 100%. The analytical sensitivity of both LC-PCR assays was <10 CFU/reaction. LC-PCR is a reliable method for the direct detection of Legionella species from BAL specimens. The Legionella genus LC-PCR assay could be performed initially; if positive, L. pneumophila species-specific LC-PCR could then be performed (if species differentiation is desired). The speed with which the LC-PCR procedure can be performed offers significant advantages over both culture-based methods and conventional PCR techniques. In contrast, for the methods evaluated, culture was the best for detecting multiple Legionella species in lung tissue. WS staining, Legionella genus LC-PCR, and L. pneumophila species-specific ISH were useful as rapid tests with lung tissue.

Characterization of culture-derived spiral bacteria by 16S ribosomal RNA gene sequence analysis

Broad range amplification and sequence analysis of the 16S ribosomal RNA gene was used to identify three spiral-form organisms. The agents were identified as Campylobacter fetus, "Flexispira rappini", and Borrelia burgdorferi, respectively, using either proprietary or public sequence databases. In each case, the rDNA sequence showed 99-100% homology with known sequence data. Sequence-based analysis for each isolate required only 2-3 days, whereas traditional means of identification took 8-12 days to complete. The identification of spirochetes and vibrio-like agents from human clinical samples is often time consuming and results may be difficult to interpret, sometimes due to atypical phenotypic characteristics. Analysis of 16S rDNA or other molecular targets may provide a way to accurately and rapidly characterize isolates that are recalcitrant to speciation.

Identification of coryneform bacterial isolates by ribosomal DNA sequence analysis

Identification of coryneform bacteria to the species level is important in certain circumstances for differentiating contamination and/or colonization from infection, which influences decisions regarding clinical intervention. However, methods currently used in clinical microbiology laboratories for the species identification of coryneform bacteria are often inadequate. We evaluated the MicroSeq 500 16S bacterial sequencing kit (Perkin-Elmer Biosystems, Foster City, Calif.), which is designed to sequence the first 527 bp of the 16S rRNA gene for bacterial identification, by using 52 coryneform gram-positive bacilli from clinical specimens isolated from January through June 1993 at the Mayo Clinic. Compared to conventional and supplemented phenotypic methods, MicroSeq provided concordant results for identification to the genus level for all isolates. At the species level, MicroSeq provided concordant results for 27 of 42 (64.3%) Corynebacterium isolates and 5 of 6 (83.3%) Corynebacterium-related isolates, respectively. Within the Corynebacterium genus, MicroSeq gave identical species-level identifications for the clinically significant Corynebacterium diphtheriae (4 of 4) and Corynebacterium jeikeium (8 of 8), but it identified only 50.0% (15 of 30) of other species (P < 0.01). Four isolates from the genera Arthrobacter, Brevibacterium, and Microbacterium, which could not be identified to the species level by conventional methods, were assigned a species-level identification by MicroSeq. The total elapsed time for running a MicroSeq identification was 15.5 to 18.5 h. These data demonstrate that the MicroSeq 500 16S bacterial sequencing kit provides a potentially powerful method for the definitive identification of clinical coryneform bacterium isolates.

Comparison of phenotypic and genotypic techniques for identification of unusual aerobic pathogenic gram-negative bacilli

Rapid and accurate identification of bacterial pathogens is a fundamental goal of clinical microbiology, but one that is difficult or impossible for many slow-growing and fastidious organisms. We used identification systems based on cellular fatty acid profiles (Sherlock; MIDI, Inc., Newark, Del.), carbon source utilization (Microlog; Biolog, Inc., Hayward, Calif.), and 16S rRNA gene sequence (MicroSeq; Perkin-Elmer Applied Biosystems Division, Foster City, Calif.) to evaluate 72 unusual aerobic gram-negative bacilli isolated from clinical specimens at the Mayo Clinic. Compared to lengthy conventional methods, Sherlock, Microlog, and MicroSeq were able to identify 56 of 72 (77.8%), 63 of 72 (87.5%), and 70 of 72 (97.2%) isolates to the genus level (P = 0.002) and 44 to 65 (67.7%), 55 of 65 (84.6%), and 58 of 65 (89.2%) isolates to the species level (P = 0.005), respectively. Four Acinetobacter and three Bordetella isolates which could not be identified to the species level by conventional methods were identified by MicroSeq. In comparison to the full 16S rDNA sequences, the first 527 bp provided identical genus information for all 72 isolates and identical species information for 67 (93.1%) isolates. These data show that MicroSeq provides rapid, unambiguous identification of clinical bacterial isolates. The improved turnaround time provided by genotypic identification systems may translate into improved clinical outcomes.

Determination of 16S rRNA sequences of enterococci and application to species identification of nonmotile Enterococcus gallinarum isolates

The 16S rRNA sequences of enterococcal species E. faecium, E. faecalis, E. gallinarum, E. casseliflavus/flavescens, E. dispar, E. pseudoavium, E. sulfureus, E. malodoratus, E. raffinosus, E. cecorum, E. hirae, E. saccharolyticus, E. seriolicida, E. mundtii, E. avium, E. durans, E. columbae, and E. solitarius are presented herein. These data were utilized to confirm the species identification of two nonmotile E. gallinarum isolates which had been previously phenotypically identified as E. faecium. The implications of this finding are discussed.

Cosegregation of a novel Bartonella species with Borrelia burgdorferi and Babesia microti in Peromyscus leucopus

During surveillance for various tickborne pathogens in the upper Midwest during the summer and early fall of 1995, a Bartonella-like agent was detected in the blood of mice that were concurrently infected with Borrelia burgdorferi or Babesia microti (or both). The organism was isolated in pure culture after inoculation of blood from wild-caught mice into C.B-17 scid/scid mice. Phylogenetic analysis of the 16S rRNA and the citrate synthase genes showed that the novel Bartonella species and a Bartonella isolate from a mouse captured on Martha's Vineyard, Massachusetts, were closely related to each other and secondarily related to Bartonella grahamii and Bartonella vinsonii. Further analysis of Peromyscus leucopus blood and tissue samples demonstrated that the novel Bartonella species was exclusively found in conjunction with B. burgdorferi and B. microti. Patent coinfection with these agents may be relatively frequent in naturally infected mice.

Bordetella holmesii-like organisms associated with septicemia, endocarditis, and respiratory failure

We recovered an unusual bacterial strain from blood or sputum of three patients with septicemia, endocarditis, and/or respiratory failure. The three isolates were thin, curved, gram-negative, light brown, pigment-producing bacilli with variable catalase activity. They were asaccharolytic, oxidase-negative, nonmotile, and fastidious. Identification was not possible on the basis of these characteristics alone or in combination with cellular fatty acid profiles. Nucleic acid amplification and sequence analysis of the 16S rRNA gene revealed that all three isolates were identical and most closely related to the emerging pathogen Bordetella holmesii, diverging from the published sequence at three nucleotide positions (99.8% similarity). Isolation of a B. holmesii-like pathogen from sputum suggests that, in addition to producing septicemia, the organism may inhabit the respiratory tract like other Bordetella species.

DNA sequence variation within vanA, vanB, vanC-1, and vanC-2/3 genes of clinical Enterococcus isolates

We studied the DNA sequence variation of van genes of 34 isolates of Enterococcus spp. The isolates containing the vanB gene exhibited between 0 and 41 base pair changes per 801 bp studied when the vanB sequences were compared to that of the reference strain Enterococcus faecalis V583. The isolates carrying the vanC-2 gene exhibited between 0 and 23 base pair changes per 346 bp studied when the vanC-2 sequences were compared to that of the reference strain E. casseliflavus ATCC 25788. Little variation was noted in the vanA and vanC-1 genes.

Comparison of agar dilution, broth microdilution, E-test, disk diffusion, and automated Vitek methods for testing susceptibilities of Enterococcus spp. to vancomycin

An evaluation was undertaken to determine the optimal method for testing the susceptibilities of 100 clinical isolates and two reference strains of Enterococcus spp. to vancomycin in vitro. Six testing methods were studied by using the following media and incubation times: agar screen with the Synergy Quad Plate (Remel, Lenexa, Kans.), an in-house-prepared brain heart infusion (BHI) agar plate, and an in-house-prepared Mueller-Hinton (MH) agar plate, all incubated for 24 or 48 h; broth microdilution (Sensititre Just One Strip; AccuMed International, Inc., West Lake, Ohio) with BHI or cation-adjusted MH broth incubated for 24 or 48 h; agar dilution with BHI or MH agar incubated for 24 or 48 h; epsilometer test (E test; AB BioDisk, Solna, Sweden) with BHI or MH agar incubated for 24 or 48 h; disk diffusion with BHI or MH agar incubated for 24 or 48 h; and the automated Vitek method with the gram-positive susceptibility Staphylococcus aureus card and R02.03 software (bioMerieux, Inc., Hazelwood, Mo.). Growth failures occurred with MH media (n = 6) but not with BHI media. One growth failure occurred with the Vitek method. Results for each testing method for each Enterococcus strain were interpreted as susceptible, intermediate, or resistant according to current National Committee for Clinical Laboratory Standards (NCCLS) criteria and compared to the vancomycin resistance genotype (i.e., vanA, vanB, vanC-1, or vanC-2/3). For all methods, extension of the incubation time from 24 h to 48 h either produced no difference in the results or gave poorer results. The following methods produced no very major or major interpretive errors: broth microdilution with BHI media incubated for 24 h, agar dilution with BHI media incubated for 24 or 48 h, and E test with BHI media incubated for 24 or 48 h. Unacceptable frequencies of very major errors (> 1%) occurred with all methods for which MH media were used. Minor interpretive errors were frequent with all methods. These minor interpretive errors also occurred most frequently with Enterococcus strains with vanC genes, which encoded low-level vancomycin resistance (MIC < or = 8 microg/ml), as opposed to Enterococcus strains which possessed vanA or vanB genes, which encoded higher-level vancomycin resistance (MIC > or = 64 microg/ml). Modification of NCCLS breakpoints, especially for motile Enterococcus spp. (E. casseliflavus, E. flavescens, and E. gallinarum), may resolve this problem; however, in the current study, one E. faecalis strain and one E. faecium strain carried only the vanC gene. The agar screen method may also require reformulation. The current agar screen plate contains 6 microg of vancomycin per ml, which may not detect all low-level resistance associated with vanC genotypes. Nevertheless, the clinical significance of this low-level vancomycin resistance remains unknown.

Multiplex PCR detection of vanA, vanB, vanC-1, and vanC-2/3 genes in enterococci

Vancomycin-resistant enterococci (VRE) are increasingly isolated from clinical specimens. One hundred clinical isolates of enterococci (E. casseliflavus/E. flavescens [n = 10], E. faecalis [n = 34], E. faecium [n = 43], E. avium [n = 1], E. gallinarum [n = 11], and E. raffinosus [n = 1]) were examined for the presence of vanA, vanB, vanC-1, and vanC-2/3 genes by a single multiplex PCR performed directly with colonies from blood agar plates. Six previously characterized VRE strains which carry either vanA, vanB, vanC-1, or vanC-2 genes were used as controls. To discriminate among van genes, the PCR amplicons were digested with MspI and were electrophoresed on agarose gels. Because of significant sequence homology between vanC-2 and vanC-3 genes, this assay is unable to discriminate these genes from each other; therefore, these are referred to as vanC-2/3 genes. PCR products were detected in 63 of the 100 clinical isolates. The restriction fragment length patterns were consistent with vanA for 10 strains, vanB for 30 strains, vanC-1 for 12 strains, vanC-2 for 6 strains, and vanA and vanC-1 for 1 strain. The vancomycin MICs for the isolates with restriction fragment length patterns consistent with vanA and vanB were all > and = 64 micrograms/ml. The vancomycin MICs for the isolates with restriction fragment length patterns consistent with vanC-1 or vanC-2 were 4 to 8 micrograms/ml. The vancomycin MICs for the isolates from which no PCR amplicons were produced were 2 to 4 micrograms/ml. A PCR product was produced in four isolates (vancomycin MICs, 4 to > 256 micrograms/ml) with restriction fragment length patterns differing from those for the control vanA, vanB, vanC-1, and vanC-2 isolates. DNA sequencing of these amplicons revealed that two of the four isolates had nucleic acid sequences which were closely related to the published sequence for the vanB gene and two had nucleic acid sequences which were closely related to the published sequence for the vanC-2 and vanC-3 genes. Multiplex PCR-restriction fragment length polymorphism appears to be a useful and convenient method for rapidly detecting and discriminating genotypes for vancomycin-resistant Enterococcus spp. in the clinical laboratory. In instances in which unusual restriction fragment patterns of PCR amplicons occur, DNA sequencing can be performed to discriminate van genotypes.

Application of quadFERM+ for the identification of fastidious gram-positive and gram-negative bacilli

The 2-hr quadFERM+ kit (qF) (Analytab Products, Plainview, NY) was compared with conventional tube tests for the identification of the HACEK bacteria (Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae), other Haemophilus and Kingella spp., Capnocytophaga, Corynbacterium, and Moraxella spp. Test results were identical for 296 comparisons with 74 isolates (74%). In the remaining 104 comparisons for 26 isolates, 50 reactions were identical, and qF produced a positive result in 46 of 54 discrepancies.