Safety, reactogenicity, and immunogenicity of different doses of 10-valent Extraintestinal Pathogenic Escherichia Coli (ExPEC10V) bioconjugate vaccine (VAC52416) in healthy Japanese adults aged 60-85 years in a randomized, double-blind, phase 1 study.

AIM: This phase 1 study (NCT04306302) evaluated the safety, reactogenicity, and immunogenicity of ExPEC10V (VAC52416) in healthy Japanese adults. METHOD: The randomized, double-blind, single-center study included 28-day screening, vaccination (Day 1), 30-day safety and immunogenicity follow-up and 181-day serious adverse events (SAEs) follow-up. Participants (60-85 years) were enrolled in dose-ascending approach and randomized to medium- and high-doses of ExPEC10V (n = 8 in each dose group) and placebo (n = 8). Incidence of adverse events: solicited AEs (until Day 15), unsolicited AEs (until Day 30), SAEs (until Day 181) and immunogenicity (electrochemiluminescent-based assay [ECL] and multiplex opsonophagocytic assay [MOPA]) were assessed on Day 15 and Day 30. RESULTS: Total of 24 participants were included (median age, 66.5 years; 50.0 % female). Incidence of solicited AEs was 81.3 % (local) and 18.8 % (systemic) for pooled ExPEC10V group (medium-dose ExPEC10V: 75.0 % [local], 12.5 % [systemic]; high-dose ExPEC10V: 87.5 % [local], 25.0 % [systemic]). One SAE, not vaccine-related, was reported in high-dose ExPEC10V group after Day 30, which was resolved during study. The ECL demonstrated increase in binding antibody titers, which was maintained from Day 15 to Day 30. For all serotypes, the geometric mean fold increases from baseline on Day 15 ranged from 2.51 to 10.60 and 1.97-5.23 for medium- and high-dose groups, respectively. The MOPA demonstrated increase in functional antibody responses for all serotypes (except O8) at Day 15 which was maintained from Day 15 to Day 30. CONCLUSIONS: ExPEC10V medium- and high-doses were well tolerated with an acceptable safety profile without any significant safety issues in healthy Japanese participants.

Global Distribution of O Serotypes and Antibiotic Resistance in Extraintestinal Pathogenic Escherichia coli Collected From the Blood of Patients With Bacteremia Across Multiple Surveillance Studies.

BACKGROUND: Extraintestinal pathogenic Escherichia coli (ExPEC) is the leading cause of bacteremia worldwide, with older populations having increased risk of invasive bacterial disease. Increasing resistance to first-line antibiotics and emergence of multidrug-resistant (MDR) strains represent major treatment challenges. ExPEC O serotypes are key targets for potential multivalent conjugate vaccine development. Therefore, we evaluated the O serotype distribution and antibiotic resistance profiles of ExPEC strains causing bloodstream infections across 4 regions. METHODS: Blood culture isolates from patients aged ≥60 years collected during 5 retrospective E. coli surveillance studies in Europe, North America, Asia-Pacific, and South America (2011-2017) were analyzed. Isolates were O serotyped by agglutination; O genotyping was performed for nontypeable isolates. Antimicrobial susceptibility testing was also conducted. RESULTS: Among 3217 ExPEC blood culture isolates, the most ubiquitous O serotype was O25 (n = 737 [22.9%]), followed by O2, O6, O1, O75, O15, O8, O16, O4, O18, O77 group, O153, O9, O101/O162, O86, and O13 (prevalence of ≥1%). The prevalence of these O serotypes was generally consistent across regions, apart from South America; together, these 16 O serotypes represented 77.6% of all ExPEC bacteremia isolates analyzed. The overall MDR frequency was 10.7%, with limited variation between regions. Within the MDR subset (n = 345), O25 showed a dominant prevalence of 63.2% (n = 218). CONCLUSIONS: Predominant O serotypes among ExPEC bacteremia isolates are widespread across different regions. O25 was the most prevalent O serotype overall and particularly dominant among MDR isolates. These findings may inform the design of multivalent conjugate vaccines that can target the predominant O serotypes associated with invasive ExPEC disease in older adults.

Intake assessments of salivary cortisol, survey responses, and adverse childhood experiences are associated with recovery success in an abstinence-based treatment program for substance use disorders.

BACKGROUND: Connecting patients to treatment for a substance use disorder (SUD) that satisfies their needs is often complicated by confounding factors. A reliable measurement of patients' underlying stress level may be helpful because it often reflects many of the same confounders as their SUD. Whereas cortisol levels reflect physiological responses to stress, patients' cortisol levels during recovery from an SUD may serve as biomarkers for stressors that result in poor treatment outcomes, including early discontinuation of treatment. However, further exploration of the relationship between patients' cortisol levels and their treatment outcomes is needed for this approach to be clinically useful. METHODS: We enrolled participants from an abstinence-based, male-only, residential alcohol and drug recovery program to examine the relationship between salivary cortisol, stress exposure, ACEs, and treatment retention. RESULTS: Participants who remained in the program <90 days had significantly higher initial cortisol levels than those who remained ≥90 days (0.62 ± 0.074 µg/dl vs. 0.36 ± 0.037 µg/dl). Kaplan-Meier curves differed significantly when we grouped participants according to whether their cortisol level was below or above the overall average of 0.49 ± 0.044 µg/dl, with the median numbers of days before discontinuing being 110 and 60, respectively. A Cox proportional hazards model indicated that elevated salivary cortisol (with increases in µg/dl), marital/relationship status, and adverse childhood experiences (ACEs) score correlated significantly with hazards of discontinuing the program (hazard ratios for the three factors were 3.49, 2.39, and 1.50, respectively). DISCUSSION: Cortisol level may predict, at least partially, SUD treatment program retention regardless of individuals' numerous confounding factors or the substance used. If this approach is validated, it could enable providers to consider patients' cortisol levels at the time of admission to treatment to facilitate their retention in treatment and thereby enhance their recovery.

Inclusion of Positive Self-reporting by Mothers of Substance Exposed Neonates Increases the Predictability of NAS Severity Over Toxicology Alone.

OBJECTIVES: The rise in opioid use among pregnant women has resulted in an increase in the incidence of neonatal abstinence syndrome (NAS). Despite the focus on opioid use, prenatal polysubstance exposure is often associated with NAS diagnosis and severity. Drug toxicology screens such as urine drug screens and umbilical cord toxicology are dependent upon the substance, timing, frequency, and dose to detect substances present and can underestimate the neonatal exposure. The aim of this study was to identify the predictability of the consequences of prenatal polysubstance exposure versus opioid only exposure based on toxicology and toxicology plus self-report. METHODS: Neonates > 35 weeks gestation with prenatal opioid exposure were included in this retrospective data analysis. NAS was identified using maternal urine drug screen (UDS) toxicology, self-reported exposure during pregnancy, and neonatal toxicology. Analysis was conducted using Stata 15.1 utilizing McNemar's test, chi-square for categorical outcomes, and Wilcoxon test for numerical outcomes. RESULTS: A statistically significant difference in length of stay and length of treatment with poly-exposed neonates was observed when maternal self-report was considered with toxicology, but not with toxicology alone. This trend was observed for cumulative hospital length of stay as well as length and dose of treatment. CONCLUSIONS FOR PRACTICE: The findings in this report demonstrate that self-report is important for identifying substance of exposure. Three substances in particular that often require a change in treatment paradigm went undetected by toxicology were Gabapentin (20.9% of the population), Heroin (20.5% of the population), and Benzodiazepines (8.5% of the population). A healthy rapport with patients is often critical to effective clinical practice. Women with substance use disorder anticipate negative reactions from healthcare providers. Empathetic interview techniques to facilitate accurate disclosure may be more important to the treatment of the exposed neonate.

Neonatal Opioid Withdrawal Syndrome: A Developmental Care Approach.

Tens of thousands of infants are impacted yearly by prenatal opioid exposure. The term neonatal opioid withdrawal syndrome (NOWS) is now replacing the more familiar term neonatal abstinence syndrome (NAS). Ongoing debate continues related to standard regimens for treatment of this oftentimes perplexing condition. Historically, treatment has focused on pharmacologic interventions. However, there is limited research that points to nonpharmacologic methods of treatment as viable options, whether alone or in addition to pharmacologic interventions. This article, utilizing a review of pertinent literature, outlines the physical aspects of NOWS, including its pathophysiology and the resulting physical clinical signs. In addition, we present an overview of how age-appropriate, nonpharmacologic interventions, centered on developmental care, may be a valuable approach to organize and prioritize routine care for these infants, their families, and the health care team facing the challenges of NOWS. Finally, the need for further research to better define evidence-based standards of care for these infants and their families is discussed.

An Atypical Withdrawal Syndrome in Neonates Prenatally Exposed to Gabapentin and Opioids.

We report a retrospective case series of 19 infants exposed to both opioids and gabapentin prenatally. We describe a unique behavioral phenotype in 15 of these infants and report a treatment strategy.

Evaluation of clonality and carbapenem resistance mechanisms among Acinetobacter baumannii-Acinetobacter calcoaceticus complex and Enterobacteriaceae isolates collected in European and Mediterranean countries and detection of two novel ß-lactamases, GES-22 and VIM-35.

We evaluated doripenem-resistant Acinetobacter baumannii-Acinetobacter calcoaceticus complex (ACB; n = 411) and Enterobacteriaceae (n = 92) isolates collected from patients from 14 European and Mediterranean countries during 2009 to 2011 for the presence of carbapenemase-encoding genes and clonality. Following susceptibility testing, carbapenem-resistant (doripenem MIC, >2 µg/ml) isolates were screened for carbapenemases. New ß-lactamase genes were expressed in a common background and susceptibility was tested. Class 1 integrons were sequenced. Clonality was evaluated by pulsed-field gel electrophoresis and multilocus sequence typing (Pasteur scheme). Relative expression of ß-lactam intrinsic resistance mechanisms was determined for carbapenemase-negative Enterobacteriaceae. ACB and Enterobacteriaceae displayed 58.9 and 0.9% doripenem resistance, respectively. bla(OXA-23), bla(OXA-58), and bla(OXA-24/OXA-40) were detected among 277, 77, and 29 ACB, respectively (in 8, 6, and 5 countries). Ten Turkish isolates carried bla(GES-11) or bla(GES-22). GES-22 (G243A and M169L mutations in GES-1) had an extended-spectrum ß-lactamase profile. A total of 33 clusters of ≥ 2 ACB isolates were observed, and 227 isolates belonged to sequence type 2/international clone II. Other international clones were limited to Turkey and Israel. Doripenem-resistant Enterobacteriaceae increased significantly (0.7 to 1.6%), and 15 blaKPC-2- and 22 blaKPC-3-carrying isolates, mostly belonging to clonal complexes 11 and 258, were observed. Enterobacteriaceae isolates producing OXA-48 (n = 16; in Turkey and Italy), VIM-1 (n = 10; in Greece, Poland, and Spain), VIM-26 (n = 1; in Greece), and IMP-19, VIM-4, and the novel VIM-35 (n = 1 each from Poland) were detected. VIM-35 had one substitution compared to VIM-1 (A235T) and a similar susceptibility profile. One or more resistance mechanisms were identified in 4/6 carbapenemase-negative Enterobacteriaceae. This broad evaluation confirms results from country-specific surveys and shows a highly diverse population of carbapenemase-producing ACB and Enterobacteriaceae in Europe and Mediterranean countries.

Epidemiology and carbapenem resistance mechanisms of carbapenem-non-susceptible Pseudomonas aeruginosa collected during 2009-11 in 14 European and Mediterranean countries.

OBJECTIVES: To evaluate the genetic relatedness and carbapenem resistance mechanisms among carbapenem-non-susceptible Pseudomonas aeruginosa collected during 2009-11 in 14 European and Mediterranean countries. METHODS: Doripenem-non-susceptible (MIC >2 mg/L) isolates were tested for susceptibility to imipenem, meropenem, doripenem, aztreonam, ceftazidime and cefepime with and without phenyl-arginine-ß-naphthylamide (PAßN) (efflux inhibitor) and/or cloxacillin (AmpC inhibitor). Carbapenemase screening was performed by PCR and sequencing. Expression of chromosomal ampC, mexA, mexC, mexE and mexX was determined by quantitative real-time PCR using P. aeruginosa PAO1 or a group of susceptible isolates as baseline. Clonality was evaluated by PFGE and multilocus sequence typing. RESULTS: Among 529 (25.6% overall) carbapenem-non-susceptible P. aeruginosa, 106 were positive for metallo-ß-lactamase (MßL) genes encoding VIM-2 (76 strains), VIM-4 (14), VIM-1 (7) and VIM-5 (5). IMP-15 and three new MßLs (IMP-33, VIM-36 and VIM-37) were detected in one strain each. An increasing prevalence of MßL producers was noted in 2011 (30.6%) compared with previous years (13.4% and 12.3% in 2009 and 2010, respectively). Isolates displayed high genetic diversity, with 401 unique profiles detected. CC235 and ST111 were detected among MßL-producing clusters. The PAßN/cloxacillin effect ranged from 90.0% to 56.5%/from 1.3% to 21.2%. OprD decrease/loss was the most prevalent intrinsic mechanism and was detected among 94.9% of the P. aeruginosa, followed by AmpC (44.4%) and MexAB-OprM (20.1%). When using the susceptible group of isolates as baseline, MexAB-OprM became as prevalent as OprD decrease/loss. CONCLUSIONS: Increasing MßL prevalence is worrisome in various European countries; however, intrinsic resistance mechanisms in a highly genetically diverse population of carbapenem-non-susceptible P. aeruginosa are probably a matter for greater concern in these countries.

A randomized phase 1/2a trial of ExPEC10V vaccine in adults with a history of UTI.

The safety, reactogenicity, and immunogenicity of 3 doses of ExPEC10V (VAC52416), a vaccine candidate to prevent invasive Escherichia coli disease, were assessed in a phase 1/2a study (NCT03819049). In Cohort 1, ExPEC10V was well tolerated; the high dose was selected as optimal and further characterized in Cohort 2. Cohort 2 comprised a maximum 28-day screening, vaccination (Day 1), double-blind 181-day follow-up, and open-label long-term follow-up until Year 1. Healthy participants (≥60 years) with a history of urinary tract infection (UTI) within 5 years were randomized to receive ExPEC10V or placebo. The primary endpoint evaluated the safety and reactogenicity of ExPEC10V (solicited local and systemic AEs [until Day 15]; unsolicited AEs [until Day 30], SAEs [until Day 181], and immunogenicity [Day 30]) via multiplex electrochemiluminescent (ECL) and multiplex opsonophagocytic assay (MOPA). 416 participants (ExPEC10V, n = 278; placebo, n = 138) were included (mean age [SD], 68.8 [6.52] years; female, 79.6%; White, 96.1%). The incidence of solicited AEs was higher with ExPEC10V (local, 50.0% [n = 139]; systemic, 50.0% [n = 139]) than placebo (15.9% [n = 22]; 38.4% [n = 53]); rates of unsolicited AEs were comparable (ExPEC10V, 28.4% [n = 79]; placebo, 26.1% [n = 36]). No vaccine-related SAEs or deaths were reported. ExPEC10V elicited a robust antibody-mediated immunogenic response across all serotypes with ECL (Day 30 geometric mean fold increase, 2.33-8.18) and demonstrated functional opsonophagocytic killing activity across all measured serotypes (Day 30 geometric mean fold increase, 1.81-9.68). ExPEC10V exhibited an acceptable safety profile and a robust vaccine-induced functional immunogenic response in participants with a history of UTI. Clinical trial registration details: https://clinicaltrials.gov/study/NCT03819049 .

Trauma Prevalence and Its Association With Health-Related Quality of Life in Pregnant Persons with Opioid Use Disorder.

OBJECTIVES: Trauma screening is recommended for pregnant persons with opioid use disorder (OUD), but there is limited literature on screening results from buprenorphine treatment. This study's objectives were to 1) describe the types, and severity, of traumatic events reported and 2) evaluate the associations between trauma and health-related quality of life (HRQoL). METHODS: Baseline data from an ongoing trial were analyzed. Participants were 155 pregnant persons with OUD receiving, or enrolling in, buprenorphine treatment at one of 13 sites. The experience, and relative severity, of 14 high magnitude stressors were assessed with the trauma history screen. The Patient-Reported Outcomes Measurement Information System-29+2 was used to assess 8 HRQoL domains. RESULTS: Traumatic stressors were reported by 91% of the sample (n = 155), with 54.8% reporting a lifetime persisting posttraumatic distress (PPD) event and 29.7% reporting a childhood PPD event. The most prevalent lifetime PPD event was sudden death of a close family/friend (25.8%); physical abuse was the most prevalent childhood PPD event (10.3%). Participants with lifetime PPD, relative to no PPD, reported significantly greater pain interference (P = 0.02). Participants with childhood PPD, relative to no PPD, had significantly worse HRQoL overall (P = 0.01), and worse pain intensity (P = 0.002), anxiety (P = 0.003), depression (P = 0.007), fatigue (P = 0.002), and pain interference (P < 0.001). CONCLUSIONS: A majority of pregnant persons enrolled/enrolling in buprenorphine treatment reported persisting posttraumatic distress with sudden death of close family/friend being the most prevalent originating event; clinicians should consider the impact that the opioid-overdose epidemic may be having in increasing trauma exposure in patients with OUD.

Safety, Reactogenicity, Immunogenicity, and Dose Selection of 10-Valent Extraintestinal Pathogenic Escherichia coli Bioconjugate Vaccine (VAC52416) in Adults Aged 60-85 Years in a Randomized, Multicenter, Interventional, First-in-Human, Phase 1/2a Study.

Background: ExPEC10V is a bioconjugate vaccine containing O-antigen polysaccharides of 10 extraintestinal pathogenic Escherichia coli (ExPEC) serotypes. This phase 1/2a study (NCT03819049) assessed the safety, reactogenicity, and immunogenicity of ExPEC10V (VAC52416) to prevent invasive E coli disease in elderly adults. Methods: The observer-blind, active-controlled design included a 28-day screening, vaccination, 181-day follow-up, and 1-year follow-up. Participants (60-85 years of age) were randomized to ExPEC10V low dose (antigen dose range, 4-8 µg), ExPEC10V medium dose (4-16 µg), or ExPEC10V high dose (8-16 µg); 4-valent ExPEC vaccine (ExPEC4V); or 13-valent pneumococcal conjugate vaccine (PCV13). The incidence of adverse events (AEs; solicited, day 15; unsolicited, day 30; serious AEs, day 181) and immunogenicity (electrochemiluminescent-based assay [ECL] and multiplex opsonophagocytic assay [MOPA]) were assessed. Optimal ExPEC10V dose was determined from safety data through day 30 and an immunogenicity dose selection algorithm based on day 15 ECL and MOPA results. Results: A total of 416 participants were included (median age, 64.0 years; 54.8% female). The incidences of solicited local and systemic AEs were, respectively, 44.2% and 39.4% for low-dose, 52.9% and 46.1% for medium-dose, 57.7% and 45.2% for high-dose ExPEC10V, and 74.1% and 48.1% for PCV13. Five serious AEs, not vaccine related, were reported. The ECL revealed a robust antibody response to ExPEC10V through year 1. Opsonophagocytic killing activity was detected against all but serotype O8; this lack of response against serotype O8 was linked to low assay sensitivity. Based on the totality of data, high-dose ExPEC10V was considered optimal. Conclusions: ExPEC10V was well tolerated and immunogenic in elderly adults against all but serotype O8.

Participant recruitment and retention from vulnerable populations in clinical trials is a matter of trust.

Clinical research sites can struggle with recruiting and retaining vulnerable populations. Vulnerable research participants often have significant trauma histories making traditional approaches to recruitment and retention tenuous. Due to these difficulties, vulnerable populations are often intentionally excluded from clinical research due to the additional time and work involved. While it is important to provide protections for any participant that has decreased autonomy or increased susceptibility to coercion, it is equally important to assure that individuals in vulnerable populations have access to any clinical research that might pertain to them. In addition, the new trends in the drug development industry including early-stage development, risk-identification, preventative care, and disease spread modeling are likely to include health disparate patient populations that have increased probability of vulnerability. In this article we discuss the roots of many vulnerabilities and how to foster trust for more effective recruitment and retention of vulnerable populations.

Parental Reading to Infants Improves Language Score: A Rural Family Medicine Intervention.

INTRODUCTION: Both expressive and receptive language development begins early in life. While the benefits of reading to toddlers (over 12 months old) is well-established, benefits of reading to infants (birth to 12 months old) is less established. This study's objective is to determine if consistent reading to infants improves expressive and receptive language development during the first year of life. METHODS: We prospectively randomized infants at a family medicine clinic during their 2-week-old visits and gave them a collection of books. Group A (n = 16) received no instructions, while patients in Group B (n = 18) committed to read 1 book a day. Parents in Group C (n = 18) enrolled after 34 weeks gestation, committed to read 1 book a day, and watch an infant brain development video. We obtained average book counts and both expressive and receptive language testing at standard preventative visits through 12 months. RESULTS: Language scores did not differ between randomized groups. Always reading 7 books per week led to higher expressive, receptive and combined language scores at 9 months than sometimes reading fewer than 7 books per week (P = .025, 0.009 and 0.011 respectively). These differences increased by 12 months (P = .004, 0.002, and 0.003, respectively). Instructing parents to read daily encouraged parents to read more books per week at 4 months (P = .031) and 6 months (P = .049). DISCUSSION: Early, consistent reading demonstrates improved language scores as early as 9 months of age. Setting expectations of minimal daily reading impacted daily reading compliance early in life.

Antistaphylococcal activities of the new fluoroquinolone JNJ-Q2.

The new broad-spectrum fluoroquinolone JNJ-Q2 displays in vitro activity against Gram-negative and Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and ciprofloxacin-resistant MRSA isolates. Tested with isogenic methicillin-susceptible S. aureus (MSSA) and MRSA strains bearing quinolone-resistant target mutations, JNJ-Q2 displayed MICs ≤ 0.12 µg/ml, values 16- to 32-fold lower than those determined for moxifloxacin. Overexpression of the NorA efflux pump did not impact JNJ-Q2 MICs. Inhibition of S. aureus DNA gyrase and DNA topoisomerase IV enzymes demonstrated that JNJ-Q2 was more potent than comparators against wild-type enzymes and enzymes carrying quinolone-resistant amino acid substitutions, and JNJ-Q2 displayed equipotent activity against both enzymes. In serial-passage studies comparing resistance selection in parallel MRSA cultures by ciprofloxacin and JNJ-Q2, ciprofloxacin readily selected for mutants displaying MIC values of 128 to 512 µg/ml, which were observed within 18 to 24 days of passage. In contrast, cultures passaged in the presence of JNJ-Q2 displayed MICs ≤ 1 µg/ml for a minimum of 27 days of serial passage. A mutant displaying a JNJ-Q2 MIC of 4 µg/ml was not observed until after 33 days of passage. Mutant characterization revealed that ciprofloxacin-passaged cultures with MICs of 256 to 512 µg/ml carried only 2 or 3 quinolone resistance-determining region (QRDR) mutations. Cultures passaged with JNJ-Q2 selection for up to 51 days displayed MICs of 1 to 64 µg/ml and carried between 4 and 9 target mutations. Established in vitro biofilms of wild-type or ciprofloxacin-resistant MRSA exposed to JNJ-Q2 displayed greater decreases in bacterial counts (7 days of exposure produced 4.5 to >7 log(10) CFU decreases) than biofilms exposed to ciprofloxacin, moxifloxacin, rifampin, or vancomycin.

Longitudinal survey of carbapenem resistance and resistance mechanisms in Enterobacteriaceae and non-fermenters from the USA in 2007-09.

BACKGROUND: Antibiotic resistance is problematic in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii, and is often associated with serious infections. Carbapenems are often one of the few remaining therapeutic options, so it is important to monitor carbapenem activity against these pathogens and to identify resistance mechanisms. METHODS: Carbapenem susceptibilities were determined for 14 359 Enterobacteriaceae, 3614 P. aeruginosa and 994 A. baumannii from the USA (2007-09). Klebsiella pneumoniae with doripenem MICs ≥2 mg/L (n = 88), and P. aeruginosa (n = 452), A. baumannii (n = 349) and other enterics (n = 13) with doripenem MICs ≥4 mg/L were screened for carbapenem resistance mechanisms. RESULTS: Doripenem/meropenem and imipenem susceptibilities for Enterobacteriaceae were >99% and 89%, respectively. Doripenem susceptibility (2007-09) for P. aeruginosa was 87.4%-84.1%; comparable to meropenem and higher than imipenem. For A. baumannii, doripenem susceptibility (2007-09) was 63%-58.2%; lower than imipenem and meropenem. Resistant K. pneumoniae had KPC and lacked porins OmpK35/OmpK36. In 2009, 3.4% of all K. pneumoniae possessed KPC. Five other enterics and one P. aeruginosa possessed KPC. Resistance mechanisms in P. aeruginosa were loss of porin OprD (90%), efflux (55%) and elevated AmpC activity (25%). Acquired carbapenemases OXA-23/-24 were present in 48% of resistant A. baumannii. VIM metallo-ß-lactamases were present in three P. aeruginosa and one A. baumannii isolates. CONCLUSIONS: Doripenem and meropenem were more active than imipenem against Enterobacteriaceae and P. aeruginosa from the USA. Carbapenem resistance mechanisms included serine carbapenemases, elevated AmpC activity, efflux and porin deficiencies occurring mostly in P. aeruginosa. Metallo-ß-lactamases were found in <0.1% of isolates.

Effects of ceftobiprole and oxacillin on mecA expression in methicillin-resistant Staphylococcus aureus clinical isolates.

Induction of mecA by ceftobiprole and oxacillin in 18 methicillin-resistant Staphylococcus aureus clinical isolates with various SCCmec cassettes was examined using reverse transcriptase PCR. The magnitude of mecA induction, 3- to 65-fold for ceftobiprole and 2- to 69-fold for oxacillin, did not correlate with ceftobiprole MICs (or=256 microg/ml. No correlation between magnitude of induction and SCCmec type was found.

Affinity of ceftobiprole for penicillin-binding protein 2b in Streptococcus pneumoniae strains with various susceptibilities to penicillin.

Wild-type penicillin-binding protein (PBP) 2b from penicillin-susceptible Streptococcus pneumoniae had high affinity for ceftobiprole and penicillin (50% inhibitory concentrations [IC(50)s] of ≤0.15 µg/ml) but not ceftriaxone (IC(50) of >8 µg/ml). In clinical isolates, ceftobiprole and PBP 2b affinities were reduced 15- to 30-fold with a Thr-446-Ala substitution and further still with an additional Ala-619-Gly PBP 2b substitution. Ceftobiprole remained active (MICs of ≤1 µg/ml) against all strains tested and behaved more like penicillin than ceftriaxone with respect to PBP 2b binding.

Effect of MexXY overexpression on ceftobiprole susceptibility in Pseudomonas aeruginosa.

Ceftobiprole, an anti-methicillin-resistant Staphylococcus aureus broad-spectrum cephalosporin, has activity (MIC for 50% of strains tested, < or =4 microg/ml) against many Pseudomonas aeruginosa strains. A common mechanism of P. aeruginosa resistance to beta-lactams, including cefepime and ceftazidime, is efflux via increased expression of Mex pumps, especially MexAB. MexXY has differential substrate specificity, recognizing cefepime but not ceftazidime. In ceftobiprole clinical studies, paired isolates of P. aeruginosa from four subjects demonstrated ceftobiprole MICs of 2 to 4 microg/ml at baseline but 16 microg/ml posttreatment, unrelated to beta-lactamase levels. Within each pair, the level of mexXY RNA, but not mexAB, mexCD, and mexEF, increased by an average of 50-fold from baseline to posttreatment isolates. Sequencing of the negative regulatory gene mexZ indicated that each posttreatment isolate contained a mutation not present at baseline. mexXY expression as a primary ceftobiprole and cefepime resistance mechanism was further examined in isogenic pairs by using cloned mexXY and mexZ. Expression of cloned mexXY in strain PAO1 or in a baseline isolate increased the ceftobiprole MIC to that for the posttreatment isolate. In contrast, in posttreatment isolates, lowering mexXY expression via introduction of cloned mexZ decreased the ceftobiprole MIC to that for the baseline isolates. Similar changes were observed for cefepime. A spontaneous mutant selectively overexpressing mexXY displayed a fourfold elevation in its ceftobiprole MIC, while overexpression of mexAB, -CD, and -EF had a minimal effect. These data indicate that ceftobiprole, like cefepime, is an atypical beta-lactam that is a substrate for the MexXY efflux pump in P. aeruginosa.