Leveraging stewardship to promote ceftriaxone use in severe infections with low- and no-risk AmpC Enterobacterales.

AmpC ß-lactamases are associated with development of ceftriaxone resistance despite initial in vitro susceptibility, but the risk of AmpC derepression is not equal among Enterobacterales. The purpose of this study was to evaluate the impact of an AmpC stewardship intervention on the definitive treatment of low- and no-risk Enterobacterales. This was an IRB-approved, single pre-test, post-test quasi-experiment at a 5-hospital system. An AmpC stewardship intervention was implemented in July 2022 and included prescriber education, the removal of microbiology comments indicating potential for ceftriaxone resistance on therapy, and the modification of a blood PCR comment for Serratia marcescens to recommend ceftriaxone. Adults ≥18 years pre-intervention (July 2021 to December 2021) and post-intervention (July 2022 to December 2022) who received ≥72 hours of inpatient definitive therapy and had non-urine cultures growing low- and no-risk organisms (S. marcescens, Providencia spp., Citrobacter koseri, Citrobacter amalonaticus, or Morganella morganii) were included. The primary endpoint was definitive treatment with ceftriaxone. A total of 224 patients were included; 115 (51%) in pre-intervention and 109 (49%) in post-intervention. Definitive ceftriaxone therapy was prescribed more frequently after intervention [6 (5%) vs 72 (66%), P < 0.001]. After adjustment for critical illness, patients in the post-group were more likely to receive definitive ceftriaxone (adjOR, 34.7; 95% CI, 13.9-86.6). The proportion of patients requiring retreatment was 18 (15%) and 11 (10%) for pre- and post-intervention patients (P = 0.22), and ceftriaxone resistance within 30 days occurred in 5 (4%) and 2 (2%) patients in the pre- and post-group (P = 0.45). An antimicrobial stewardship intervention was associated with increased ceftriaxone prescribing and similar patient outcomes for low- and no-risk AmpC Enterobacterales.

Respiratory culture nudge improves antibiotic prescribing for Moraxella catarrhalis and Haemophilus influenzae lower respiratory tract infections.

We compared optimal antibiotic prescribing before and after implementing an interpretive ß-lactamase microbiology comment for Haemophilus influenzae and Moraxella catarrhalis in lower respiratory-tract infections. The postintervention group was associated with 5-fold increased odds of optimal de-escalation (adjusted odds ratio, 5.03; 95% confidence interval, 2.57-9.87).

A Microbiological Assay of Common Operating Room (OR) Tapes: Developing a Culture for Patient Safety.

BACKGROUND: There are no existing practices or methods to ensure cleanliness, sterility, or prevent cross-contamination when it comes to common operating room (OR) tape. The authors hypothesized that adhesive tapes used by anesthesia providers in ORs and off-site surgical areas might be colonized by microorganisms and that culturing these tape rolls would reveal significant monomicrobial and polymicrobial contamination.  Material and Methods: The primary objective of this observational cohort study was to report and compare contamination rate including polymicrobial contamination rate between tape specimens collected from storage site and specimen from the ORs, off-sites, and after use on a patient. The outcome measures were the culture reports of the adhesive tapes. The authors then designed an intervention that integrated anesthesia providers' hand hygiene and maintenance of a barrier between the OR tapes and OR surfaces. RESULTS: The authors reported gross contamination and cross-contamination among the OR off-site tapes. The contamination rates reported for tapes from OR, off-site specimens, and patient specimens were 68.2%,63.2%, and 100%, respectively. The authors again cultured adhesive tapes after the intervention and reported improved outcomes. CONCLUSIONS: The current quality improvement (QI) project identified the potential for OR tapes to serve as microbial vectors. The authors advocate environmental decontamination and anesthesia providers' hand hygiene in parallel as a part of routine anesthesia care in their practice and agree that the endotracheal tubes (ETTs) and orogastric or nasogastric tubes should be pre-packaged with single-use tape, which can be used for securing devices.

SARS-CoV-2 RT-PCR positivity and antibody prevalence among asymptomatic hospital-based health care workers.

BACKGROUND: The level of asymptomatic infection with SARS-CoV-2 could be substantial and among health care workers (HCWs) a source of continuing transmission of the virus to patients and co-workers. OBJECTIVES: Measure the period prevalence of SARS-CoV-2 PCR positivity and seroprevalence of SARS-CoV-2 IgG antibodies among a random sample of asymptomatic health system hospital-based health care workers (HCWs) 6½ -15½ weeks after 4/5/2020, the peak of the first surge of COVID-19 admissions. RESULTS: Of 524 eligible and consented participants from four metropolitan hospitals, nasopharyngeal swabs were obtained from 439 (83.8 %) and blood from 374 (71.4 %). Using PCR nucleic acid-based amplification (NAAT) methods, the period prevalence of SARS-CoV-2 infection was 0.23 % (95 % confidence interval (CI) 0.01 %-1.28 %; 1/439) from 5/21/20-7/16/20. The seroprevalence of SARS-CoV-2 IgG antibodies from June 17-July 24, 2020 was 2.41 % (95 % CI 1.27 %-4.51 %; 9/374). Those who were reactive were younger (median age 36 versus 44 years; p = 0.050), and those with self-reported Hispanic/Latino ethnicity had a higher seroprevalence (2/12 = 16.7 % versus 7/352 = 2.0 %; p = 0.051). There were no significant differences by sex, race, residence, hospital, unit or job type. The one employee who was found to be PCR test positive in this study was also reactive for IgG antibodies, tested 27 days later. CONCLUSIONS: The period prevalence of PCR positivity to SARS-CoV-2 and IgG seroprevalence was unexpectedly low in asymptomatic HCWs after a peak in COVID-19 admissions and the establishment of state and institutional infection control policies, suggesting that routine screening tests while community prevalence is relatively low would produce a minimal yield.

Comparison of bacterial maxillary sinus cultures between odontogenic sinusitis and chronic rhinosinusitis.

BACKGROUND: Bacterial odontogenic sinusitis (ODS) is distinct from other forms of rhinosinusitis. Diagnosing ODS can be challenging because of nonspecific clinical presentations and underrepresentation in the literature. The purpose of this study was to compare maxillary sinus bacterial cultures between patients with ODS and chronic rhinosinusitis (CRS), to determine whether certain bacteria are associated with ODS. METHODS: This was a retrospective case-control study of 276 consecutive patients from August 2015 to August 2019 who underwent endoscopic sinus surgery (ESS) for bacterial ODS, CRS without nasal polyps (CRSsNP), or CRS with nasal polyps (CRSwNP). When present, pus was sterilely cultured from maxillary sinuses after maxillary antrostomy, and aerobic and anaerobic cultures were immediately sent for processing. Demographics and culture results were compared between ODS and CRS patients, and then separately between ODS and CRSsNP, and ODS and CRSwNP. ODS culture results were also compared between different dental pathologies (endodontic vs oroantral fistula). RESULTS: The following bacteria were significantly more likely in ODS compared to CRS: mixed anaerobes, Fusobacterium spp., Eikenella corrodens, Streptococcus intermedius, Streptococcus anginosus, and Streptococcus constellatus. Staphylococcus aureus and Pseudomonas aeruginosa were inversely related to ODS. There were no significant differences in cultures between the different dental pathologies. CONCLUSION: Certain bacteria were more likely to be associated with ODS compared to CRS when purulence was cultured from the maxillary sinus. Physicians should evaluate for an odontogenic source of sinusitis when these ODS-associated bacteria are identified in maxillary sinus cultures.

The effect of ultraviolet C radiation against different N95 respirators inoculated with SARS-CoV-2.

OBJECTIVES: There are currently no studies that have examined whether one dosage can be uniformly applied to different respirator types to effectively decontaminate SARS-CoV-2 on N95 filtering facepiece respirators (FFRs). Health care workers have been using this disinfection method during the pandemic. Our objective was to determine the effect of UVC on SARS-CoV-2 inoculated N95 respirators and whether this was respirator material/model type dependent. METHODS: Four different locations (facepiece and strap) on five different N95 FFR models (3M 1860, 8210, 8511, 9211; Moldex 1511) were inoculated with a 10 µL drop of SARS-CoV-2 viral stock (8 × 107 TCID50/mL). The outside-facing and wearer-facing surfaces of the respirators were each irradiated with a dose of 1.5 J/cm2 UVC (254 nm). Viable SARS-CoV-2 was quantified by a median tissue culture infectious dose assay (TCID50). RESULTS: UVC delivered using a dose of 1.5 J/cm2, to each side, was an effective method of decontamination for the facepieces of 3M 1860 and Moldex 1511, and for the straps of 3M 8210 and the Moldex 1511. CONCLUSION: This dose is an appropriate decontamination method to facilitate the reuse of respirators for healthcare personnel when applied to specific models/materials. Also, some straps may require additional disinfection to maximize the safety of frontline workers. Implementation of widespread UVC decontamination methods requires careful consideration of model, material type, design, and fit-testing following irradiation.

Stewardship opportunities in viral pneumonia: Why not the immunocompromised?

Antimicrobial management of viral pneumonia has proven to be a challenge in hospitalized immunocompromised patients. A host of factors contribute to the dilemma, such as diagnostic uncertainty, lack of organism identification, and clinical status of the patient. Respiratory virus panel (RVP) use was compared between 131 immunocompromised patients who received send-out (n = 56) vs in-house (n = 75) testing. Antimicrobial optimization interventions consisted of antiviral addition/discontinuation, antibiotic discontinuation/de-escalation, or modification of immunosuppressive regimen. After implementation of an in-house test with audit and feedback, turnaround time of the RVP was reduced from 46.7 to 5.5 hours (P < .001) and time to intervention was reduced from 52.1 to 13.9 hours (P < .001), yet the frequency of antimicrobial optimization interventions was unchanged (30.7% vs 35.7%). Differences were not observed in duration of empiric antibiotic therapy or length of stay. The overall discontinuation rate for patients tested with a RVP was low (4.6%), and those with positive RVP (n = 43) had antibiotics stopped in 14% of cases. Bacterial pneumonia coinfection was confirmed in 2 patients. Further systematic efforts should be taken to reduce antibiotic use in viral pneumonia and identify the major barriers in the immunocompromised population.

Characterization of Salmonella Isangi possessing a CTX-M15 ESBL associated with an outbreak in a US Hospital.

Over an approximately 50-day period in 2015, an outbreak of CTX-M-15 extended spectrum ß-lactamase-(ESBL)-possessing Salmonella Isangi occurred among 19 adult surgical patients and one healthcare worker (HCW) at a large urban tertiary care hospital in the United States. A total of 45 S. Isangi isolates were isolated from stool (35), blood (4), urine (3), respiratory (2), and wound (1) cultures. Phenotypically, all but three isolates demonstrated resistance to ampicillin, ampicillin/sulbactam, ceftriaxone, and cefepime, and one isolate was resistant to ertapenem. Genotypically, a single CTX-M-15 ESBL was identified in all but three isolates by real-time PCR. Interestingly, two of the CTX-M-15 negative, susceptible isolates were isolated from a single patient who initially had a CTX-M positive, resistant strain. Isolates were clonally related, including both resistant and susceptible strains, as confirmed by pulse field gel electrophoresis (PFGE). This is the first case of a novel Salmonella outbreak at this hospital, and we believe it to be the first case of an S. Isangi serotype outbreak in the United States.

Evaluation of a microarray-based assay for rapid identification of Gram-positive organisms and resistance markers in positive blood cultures.

Rapid identification of pathogens directly from positive blood cultures can play a major role in reducing patient mortality rates. We evaluated the performance of the Verigene Gram-Positive Blood Culture (BC-GP) assay (Nanosphere Inc., Northbrook, IL) for detection of commonly isolated Gram-positive organisms as well as associated resistance markers from positive blood cultures. Positive blood cultures (VersaTREK; Trek Diagnostic Systems, Independence, OH) from 203 patients with Gram-positive organism infections were analyzed using the BC-GP assay within 12 h for the detection of 12 different organisms, including staphylococci, streptococci, and enterococci, as well as for the presence of 3 resistance markers (mecA, vanA, and vanB). Results were compared to those of routine laboratory methods for identification and susceptibility testing. For identification of organisms and detection of resistance markers in 178 monomicrobial positive blood cultures, the BC-GP assay showed 94% and 97% concordance, respectively, with routine methods. After 25 polymicrobial cultures were included, the results showed 92% and 96% agreement for identification and resistance markers, respectively, for a total of 203 positive cultures. In 6/25 polymicrobial cultures, at least 1 isolate was not detected. Concordance levels for detection of major pathogens such Staphylococcus aureus (n = 45) and enterococci (n = 19) were 98% and 95%, respectively. Agreement levels for detection of resistance markers such as mecA and vanA/B were 92% and 100%, respectively. The BC-GP assay is capable of providing rapid identification of Gram-positive cocci as well as detection of resistance markers directly from positive blood cultures at least 24 to 48 h earlier than conventional methods.

Treatment and clinical outcomes of urinary tract infections caused by KPC-producing Enterobacteriaceae in a retrospective cohort.

BACKGROUND: Optimal treatment regimens for infections caused by Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae are not well-defined. OBJECTIVES: This study describes the treatment and outcomes in patients with urinary tract infection (UTI) caused by KPC-producing Enterobacteriaceae. METHODS: This retrospective cohort study analyzed data from adult inpatients with bacteriuria caused by KPC-positive organisms treated at Barnes-Jewish Hospital from June 1, 2006, to February 1, 2008. KPC-positive isolates were identified utilizing disk-diffusion susceptibility testing and confirmed to contain bla(KPC) via molecular methods. RESULTS: Twenty-one patients met the inclusion criteria and all were classified as having symptomatic UTI. The majority of patients were female (15/21 [71%]), and the mean (SD) age was 62.4 (15.2) years. Successful clinical and microbiologic responses were observed in 16 patients (76%) for both outcomes. Patients with urinary catheters had them removed or replaced in 9 of 15 cases (60%). Antibiotics active against the isolated pathogen were provided in 14 of 21 cases (67%), often after considerable delay (median, 72.5 hours [range, 4-312 hours]). All 7 patients receiving aminoglycoside therapy had successful clinical and microbiologic responses, and in vitro testing of an extended antibiotic panel revealed high susceptibility rates for tigecycline (28/29 [97%]), minocycline (22/29 [76%]), and fosfomycin (25/29 [86%]) against the KPC-positive isolates. CONCLUSIONS: Although receipt of appropriate therapy was delayed in many cases, clinical outcomes investigated revealed [corrected] high rates of successful response in this defined group of patients Aminoglycosides and tetracycline derivatives suggested therapeutic promise in the treatment of KPC-producing Enterobacteriaceae UTI.

Comparison of time to positivity of the VersaTREK® REDOX 80-mL and the REDOX EZ draw 40-mL blood culture bottles for common bacterial bloodstream pathogens.

The VersaTREK(®) microbial detection system offers 2 media formulations, an aerobic and an anaerobic bottle available in a 40-mL direct draw format and an 80-mL format. The 40-mL EZ Draw(®) bottle can be inoculated with a maximum volume of 5 mL, while the REDOX 80-mL bottle accommodates a 10-mL volume. The effect of volume of blood inoculum on time to positivity (TTP) has not been clearly established with these bottle types. This study utilized simulated blood cultures seeded with clinically relevant microorganisms in human blood to evaluate the impact of inoculum volume and organism load on TTP for the 2 bottle types. For 13/15 organisms, the EZ Draw bottle flagged positive earlier than the REDOX 80-mL bottles. The lower volume of blood inoculum did not negatively impact TTP using the EZ Draw blood culture bottles as compared to REDOX 80-mL bottles.

Evaluation of a real-time PCR assay for the detection of the Klebsiella pneumoniae carbapenemase genes in microbiological samples in comparison with the modified Hodge test.

Transfer of the bla(KPC) genes encoding the Klebsiella pneumoniae carbapenemase (KPC) are increasingly responsible for emerging carbapenem resistance. The modified Hodge test (MHT) is recommended for the detection of KPC. We compared MHT with a real-time polymerase chain reaction (PCR) assay targeting common subtypes of bla(KPC), using previously described forward and reverse primer sequences. The PCR product was detected using SYBR Green (Applied Biosystems, Foster City, CA) and confirmed by melt curve analysis. PCR was positive in 96% (52/54) of isolates that were MHT+, 90% (28/31) of MHT- isolates were PCR-, and the results were strongly correlated (P = .0001; Fisher exact test). The PCR assay is a sensitive, specific, and rapid test for detecting bla(KPC) genes. It could help optimize patient care by reducing the time taken to institute appropriate antimicrobial therapy and so help improve patient outcomes.

Presence of the KPC carbapenemase gene in Enterobacteriaceae causing bacteremia and its correlation with in vitro carbapenem susceptibility.

During 6 months, we obtained Enterobacteriaceae isolates from patients with gram-negative bacteremia at a 1,250-bed teaching hospital in St. Louis, MO, and compared carbapenem susceptibilities with the presence of bla(KPC), a transferable carbapenemase gene. Three (1.2%) out of 243 isolates were bla(KPC) positive. Ertapenem nonsusceptibility had a low positive predictive value.

A new chromogenic agar medium, chromID VRE, to screen for vancomycin-resistant Enterococcus faecium and Enterococcus faecalis.

We compared the performance of a chromogenic agar medium chromID VRE (bioMérieux, Marcy-l'Etoile, France) designed to recover and identify vancomycin-resistant enterococci (VRE) from clinical specimens with bile esculin azide vancomycin (BEAV) agar. For this study, 120 stool specimens were plated on chromID VRE and BEAV and examined after 24 and 48 h. At 24 h, the sensitivity and specificity were as follows: BEAV, 90.2% and 73%, respectively; chromID VRE, 86.3% and 100.0%, respectively. Furthermore, we determined that the sensitivity and specificity of chromID VRE for Enterococcus faecium were 85.4% and 100%, respectively, and for Enterococcus faecalis, 90% and 100%, respectively. We conclude that chromID VRE provides an equivalent sensitivity for the recovery of VRE from stool specimens, with improved specificity, and the added advantage of providing differentiation between vancomycin-resistant E. faecium and E. faecalis.

Insertional mutation of marA vitiates inducible multiple antimicrobial resistance in Salmonella enterica subsp. enterica serovar Choleraesuis.

marA has been shown to mediate a multiple antimicrobial resistance (MAR) phenotype following induction in some members of the Enterobacteriaceae. When Salmonella Choleraesuis was exposed to inducing agents they displayed higher minimal inhibitory concentrations (MIC) to multiple antimicrobial agents and an increase in marA expression as determined by northern hybridization analysis. The objective of the present study was to determine if mutation of marA vitiated multiple antimicrobial resistance inducibility in S. Choleraesuis. A loss-of-function mutation of marA in a single S. Choleraesuis isolate was created by insertion of the dihydrofolate reductase (DHFR) gene cassette within marA using double homologous recombination. This mutation was complemented with an expression plasmid possessing marA under the control of an IPTG-inducible promoter. Mutation and complementation of marA was verified using polymerase chain reaction, Northern hybridization, and Western blotting assays. Minimum inhibitory concentrations (MICs) of tetracycline, chloramphenicol, nalidixic acid, and rifampin were determined against induced and uninduced wildtype, marA-disrupted and marA-complemented strains using a microbroth dilution assay. Minimum inhibitory concentrations against induced wildtype and marA-complemented strains increased four- to eight-fold for all antimicrobials tested when compared to the uninduced strains while the MICs of the induced marA-disrupted mutant remained the same. However, this increase was abrogated when the cells were grown in the presence of the efflux pump inhibitor compound EPI phe-arg-naphthylamide. The results indicate that a functional marA is solely required for an inducible multiple antimicrobial resistance phenotype in S. Choleraesuis.

Phenotypic evidence for inducible multiple antimicrobial resistance in Salmonella choleraesuis.

Multiple antimicrobial resistance (MAR) in Salmonella choleraesuis is becoming a major concern. It has been demonstrated that a MAR phenotype can be induced in Escherichia coli and other members of the Enterobacteriaceae by exposing the isolates to salicylates, various antimicrobials, or organic solvents used to combat and control bacterial infection. Therefore the purpose of the present study was to determine whether this marA-associated MAR-phenotype is inducible in S. choleraesuis. Isolates used in the present study were able to withstand toxic effects of the organic solvent cyclohexane naturally, or following exposure to the inducing compounds salicylate, tetracycline, or chloramphenicol. All isolates possessed fragments of marA with the predicted size of 408 bp when amplified using marA-specific primers by PCR. The resulting PCR products that were sequenced revealed that amplified S. choleraesuis marA was 99% and 85% homologous to the published Salmonella typhimurium and E. coli marA sequences respectively. Minimum inhibitory concentrations of tetracycline (P<0.08), chloramphenicol (P<0.001), rifampin (P<0.08), and nalidixic acid (P<0.001) against cyclohexane-tolerant mutants were significantly increased when compared with wild-type S. choleraesuis. Northern hybridization signals for both marA and acrB were increased in the induced isolates when compared to uninduced controls while soxS expression did not change between induced and uninduced cultures. The results suggest that marA is present in S. choleraesuis and a MAR-phenotype is inducible in S. choleraesuis presumably due to the overexpression of marA and acrB and not to the overexpression of soxS.