Extensively Drug-Resistant Shigella flexneri 2a, California, USA, 2022.

In Los Angeles, California, USA, persistent, refractory shigellosis was diagnosed in an immunocompetent man who has sex with men. Whole-genome sequencing augmented phenotypic antimicrobial susceptibility testing to comprehensively profile bacterial drug resistance and appropriately guide therapy and clear the infection.

The Path of More Resistance: a Comparison of National Healthcare Safety Network and Clinical Laboratory Standards Institute Criteria in Developing Cumulative Antimicrobial Susceptibility Test Reports and Institutional Antibiograms.

In the absence of antimicrobial susceptibility data, the institutional antibiogram is a valuable tool to guide clinicians in the empirical treatment of infections. However, there is a misunderstanding about how best to prepare cumulative antimicrobial susceptibility testing reports (CASTRs) to guide empirical therapy (e.g., routine antibiogram) versus monitoring antimicrobial resistance, with the former following guidance from the Clinical and Laboratory Standards Institute (CLSI) and the latter from the Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN). These criteria vary markedly in their exclusion or inclusion of isolates cultured repeatedly from the same patient. We compared rates of nonsusceptibility (NS) using annual data from a large teaching health care system subset to isolates eligible by either NHSN criteria or CLSI criteria. For a panel of the three most prevalent Gram-negative pathogens in combination with clinically relevant antimicrobial agents (or priority pathogen-agent combinations [PPACs]), we found that the inclusion of duplicate isolates by NHSN criteria yielded higher NS rates than when CLSI criteria (for which duplicate isolates are not included) were applied. Patients with duplicate isolates may not be representative of antimicrobial resistance within a population. For this reason, users of CASTR data should carefully consider that the criteria used to generate these reports can impact resulting NS rates and, therefore, maintain the distinction between CASTRs created for different purposes.

Adherence to the SEP-1 Sepsis Bundle in Hospital-Onset v. Community-Onset Sepsis: a Multicenter Retrospective Cohort Study.

BACKGROUND: Sepsis is the leading cause of in-hospital death. The SEP-1 sepsis bundle is a protocol for early sepsis care that requires providers to diagnose and treat sepsis quickly. Limited evidence suggests that adherence to the sepsis bundle is lower in cases of hospital-onset sepsis. OBJECTIVE: To compare sepsis bundle adherence in hospital-onset vs. community-onset sepsis. DESIGN: Retrospective cohort study using multivariable analysis of clinical data. PARTICIPANTS: A total of 4658 inpatients age 18 or older were identified by diagnosis codes consistent with sepsis or disseminated infection. SETTING: Four university hospitals in California between 2014 and 2016. MAIN OUTCOMES AND MEASURES: The primary outcome was adherence to key components of the sepsis bundle defined by the Centers for Medicare and Medicaid Services in their core measure, SEP-1. Covariates included clinical characteristics related to the patient, infection, and pathogen. KEY RESULTS: Compared with community-onset, cases of hospital-onset sepsis were less likely to receive SEP-1 adherent care (relative risk 0.33, 95% confidence interval 0.29-0.38, p < 0.001). With the exception of vasopressors (RR 1.11, p = 0.002), each component of SEP-1 evaluated-blood cultures (RR 0.76, p < 0.001), serum lactate (RR 0.51, p < 0001), broad-spectrum antibiotics (RR 0.62, p < 0.001), intravenous fluids (0.47, p < 0.001), and follow-up lactate (RR 0.71, p < 0.001)-was less likely to be performed within the recommended time frame in hospital-onset sepsis. Within the hospital, cases of hospital-onset sepsis arising on the ward were less likely to receive SEP-1-adherent care than were cases arising in the intensive care unit (RR 0.68, p = 0.004). CONCLUSIONS: Inpatients with hospital-onset sepsis receive different management than individuals with community-onset sepsis. It remains to be determined whether system-level factors, provider-level factors, or factors related to measurement explain the observed variation in care or whether variation in care affects outcomes.

Cardiovascular implantable electronic device infections due to enterococcal species: Clinical features, management, and outcomes.

BACKGROUND: Enterococcal cardiovascular implantable electronic device (CIED) infections are not well characterized. METHODS: Data from the Multicenter Electrophysiologic Device Infection Cohort, a prospective study of CIED infections, were used for descriptive analysis of adults with enterococcal CIED infections. RESULTS: Of 433 patients, 21 (4.8%) had enterococcal CIED infection. Median age was 71 years. Twelve patients (57%) had permanent pacemakers, five (24%) implantable cardioverter defibrillators, and four (19%) biventricular devices. Median time from last procedure to infection was 570 days. CIED-related bloodstream infections occurred in three patients (14%) and 18 (86%) had infective endocarditis (IE), 14 (78%) of which were definite by the modified Duke criteria. IE cases were classified as follows: valvular IE, four; lead IE, eight; both valve and lead IE, six. Vegetations were demonstrated by transesophageal echocardiography in 17 patients (81%). Blood cultures were positive in 19/19 patients with confirmed results. The most common antimicrobial regimen was penicillin plus an aminoglycoside (33%). Antibiotics were given for a median of 43 days. Only 14 patients (67%) underwent device removal. There was one death during the index hospitalization with four additional deaths within 6 months (overall mortality 24%). There were no relapses. CONCLUSIONS: Enterococci caused 4.8% of CIED infections in our cohort. Based on the late onset after device placement or manipulation, most infections were likely hematogenous in origin. IE was the most common infection syndrome. Only 67% of patients underwent device removal. At 6 months follow-up, no CIED infection relapses had occurred, but overall mortality was 24%.

Risk Factors for Colistin Resistance among Gram-Negative Rods and Klebsiella pneumoniae Isolates.

Infections due to colistin-resistant (Colr) Gram-negative rods (GNRs) and colistin-resistant Klebsiella pneumoniae isolates in particular result in high associated mortality and poor treatment options. To determine the risk factors for recovery on culture of Colr GNRs and ColrK. pneumoniae, analyses were chosen to aid decisions at two separate time points: the first when only Gram stain results are available without any bacterial species information (corresponding to the Colr GNR model) and the second when organism identification is performed but prior to reporting of antimicrobial susceptibility testing results (corresponding to the ColrK. pneumoniae model). Cases were retrospectively analyzed at a major academic hospital system from 2011 to 2016. After excluding bacteria that were intrinsically resistant to colistin, a total of 28,512 GNR isolates (4,557 K. pneumoniae isolates) were analyzed, 128 of which were Colr (i.e., MIC > 2 µg/ml), including 68 of which that were ColrK. pneumoniae In multivariate analysis, risk factors for Colr GNRs were neurologic disease, residence in a skilled nursing facility prior to admission, receipt of carbapenems in the last 90 days, prior infection with a carbapenem-resistant organism, and receipt of ventilatory support (c-statistic = 0.81). Risk factors for ColrK. pneumoniae specifically were neurologic disease, residence in a skilled nursing facility prior to admission, receipt of carbapenems in the last 90 days, receipt of an anti-methicillin-resistant Staphylococcus aureus antimicrobial in the last 90 days, and prior infection with a carbapenem-resistant organism (c-statistic = 0.89). A scoring system derived from these models can be applied by providers to guide empirical antimicrobial therapy in patients with infections with suspected Colr GNR and ColrK. pneumoniae isolates.

Attempted salvage of infected cardiovascular implantable electronic devices: Are there clinical factors that predict success?

BACKGROUND: Published guidelines mandate complete device removal in cases of cardiovascular implantable electronic device (CIED) infection. Clinical predictors of successful salvage of infected CIEDs have not been defined. METHODS: Data from the Multicenter Electrophysiologic Device Infection Collaboration, a prospective, observational, multinational cohort study of CIED infection, were used to investigate whether clinical predictors of successful salvage of infected devices could be identified. RESULTS: Of 433 adult patients with CIED infections, 306 (71%) underwent immediate device explantation. Medical management with device retention and antimicrobial therapy was initially attempted in 127 patients (29%). "Early failure" of attempted salvage occurred in 74 patients (58%) who subsequently underwent device explantation during the index hospitalization. The remaining 53 patients (42%) in the attempted salvage group retained their CIED. Twenty-six (49%) had resolution of CIED infection (successful salvage group) whereas 27 patients (51%) experienced "late" salvage failure. Upon comparing the salvage failure group, early and late (N = 101), to the group experiencing successful salvage of an infected CIED (N = 26), no clinical or laboratory predictors of successful salvage were identified. However, by univariate analysis, coagulase-negative staphylococci as infecting pathogens (P = 0.0439) and the presence of a lead vegetation (P = 0.024) were associated with overall failed salvage. CONCLUSIONS: In patients with definite CIED infections, clinical and laboratory variables cannot predict successful device salvage. Until new data are forthcoming, device explantation should remain a mandatory and early management intervention in patients with CIED infection in keeping with existing expert guidelines unless medical contraindications exist or patients refuse device removal.

Rates of and factors associated with infection in 200 909 Medicare implantable cardioverter-defibrillator implants: results from the National Cardiovascular Data Registry.

BACKGROUND: The rate of implantable cardioverter-defibrillator (ICD) infections has been increasing faster than that of implantation. We sought to determine the rate and predictors of ICD infection in a large cohort of Medicare patients. METHODS AND RESULTS: Cases submitted to the ICD Registry from 2006 to 2009 were matched to Medicare fee-for-service claims data using indirect patient identifiers. ICD infections occurring within 6 months of hospital discharge after implantation were identified by ICD-9 codes. Logistic regression was used to examine factors associated with risk of ICD infection. Of 200 909 implants, 3390 patients (1.7%) developed an ICD infection. The infection rate was 1.4%, 1.5%, and 2.0% for single, dual, and biventricular ICDs, respectively (P<0.001). Generator replacement had a higher rate compared with initial implant (1.9% versus 1.6%, P<0.001). The factors associated with infection were adverse event during implant requiring reintervention (odds ratio [OR], 2.692; 95% confidence interval [CI], 2.304-3.145), previous valvular surgery (OR, 1.525; 95% CI, 1.375-1.692), reimplantation for device upgrade, malfunction, or manufacturer advisory (OR, 1.354; 95% CI, 1.196-1.533), renal failure on dialysis (OR, 1.342; 95% CI, 1.123-1.604), chronic lung disease (OR, 1.215; 95% CI, 1.125-1.312), cerebrovascular disease (OR, 1.172; 95% CI, 1.076-1.276), and warfarin (OR, 1.155; 95% CI, 1.060-1.257). CONCLUSIONS: Patients who developed an ICD infection were more likely to have had peri-ICD implant complications requiring early reintervention, previous valve surgery, device replacement for reasons other than battery depletion, and increased comorbidity burden. Efforts should be made to carefully consider when to reenter the pocket at any time other than battery replacement.

Combination prophylactic therapy with rifampin increases efficacy against an experimental Staphylococcus epidermidis subcutaneous implant-related infection.

The incidence of infections related to cardiac devices (such as permanent pacemakers) has been increasing out of proportion to implantation rates. As management of device infections typically requires explantation of the device, optimal prophylactic strategies are needed. Cefazolin and vancomycin are widely used as single agents for surgical prophylaxis against cardiac device-related infections. However, combination antibiotic prophylaxis may further reduce infectious complications. To model a localized subcutaneous implant-related infection, a bioluminescent strain of Staphylococcus epidermidis was inoculated onto a medical-procedure-grade titanium disc, which was placed into a subcutaneous pocket in the backs of mice. In vivo bioluminescence imaging, quantification of ex vivo CFU from the capsules and implants, variable-pressure scanning electron microscopy (VP-SEM), and neutrophil enhanced green fluorescent protein (EGFP) fluorescence in LysEGFP mice were employed to monitor the infection. This model was used to evaluate the efficacies of low- and high-dose cefazolin (50 and 200 mg/kg of body weight) and vancomycin (10 and 110 mg/kg) intravenous prophylaxis with or without rifampin (25 mg/kg). High-dose cefazolin and high-dose vancomycin treatment resulted in almost complete bacterial clearance, whereas both low-dose cefazolin and low-dose vancomycin reduced the in vivo and ex vivo bacterial burden only moderately. The addition of rifampin to low-dose cefazolin and vancomycin was highly effective in further reducing the CFU harvested from the implants. However, vancomycin-rifampin was more effective than cefazolin-rifampin in further reducing the CFU harvested from the surrounding tissue capsules. Future studies in humans will be required to determine whether the addition of rifampin has improved efficacy in preventing device-related infections in clinical practice.

Variability in clinical features of early versus late cardiovascular implantable electronic device pocket infections.

BACKGROUND: Cardiovascular implantable electronic device (CIED) pocket infections are often related to recent CIED placement or manipulation, but these infections are not well characterized. The clinical presentation of CIED pocket infection, based on temporal onset related to last CIED procedure, deserves further study. METHODS: The MEDIC (Multicenter Electrophysiologic Device Infection Cohort) prospectively enrolled subjects with CIED infection. Subjects were stratified into those whose infection occurred <12 months (early) or ≥ 12 months (late) since their last CIED-related procedure. RESULTS: There were 132 subjects in the early group and 106 in the late group. There were more females (P = 0.009) and anticoagulation use (P = 0.039) in the early group. Subjects with early infections were more likely to have had a generator change or lead addition as their last procedure (P = 0.03) and had more prior CIED procedures (P = 0.023). Early infections were more likely to present with pocket erythema (P < 0.001), swelling (P < 0.001), and pain (P = 0.007). Late infections were more likely to have pocket erosion (P = 0.005) and valvular vegetations (P = 0.009). In bacteremic subjects, early infections were more likely healthcare-associated (P < 0.001). In-hospital and 6-month mortality were equivalent. CONCLUSION: A total of 45% of patients with CIED pocket infection presented >12 months following their last CIED-related procedure. Patients with early infection were more likely to be female, on anticoagulation, and present with localized inflammation, whereas those with late infection were more likely to have CIED erosion or valvular endocarditis.

Implementation of contact precautions for multidrug-resistant organisms in the post-COVID-19 pandemic era: An updated national Emerging Infections Network (EIN) survey.

OBJECTIVE: To understand how healthcare facilities employ contact precautions for patients with multidrug-resistant organisms (MDROs) in the post-coronavirus disease 2019 (COVID-19) era and explore changes since 2014. DESIGN: Cross-sectional survey. PARTICIPANTS: Emerging Infections Network (EIN) physicians involved in infection prevention or hospital epidemiology. METHODS: In September 2022, we sent via email an 8-question survey on contact precautions and adjunctive measures to reduce MDRO transmission in inpatient facilities. We also asked about changes since the COVID-19 pandemic. We used descriptive statistics to summarize data and compared results to a similar survey administered in 2014. RESULTS: Of 708 EIN members, 283 (40%) responded to the survey and 201 reported working in infection prevention. A majority of facilities (66% and 69%) routinely use contact precautions for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) respectively, compared to 93% and 92% in 2014. Nearly all (>90%) use contact precautions for Candida auris, carbapenem-resistant Enterobacterales (CRE), and carbapenem-resistant Acinetobacter baumannii. More variability was reported for carbapenem-resistant Pseudomonas aeruginosa and extended-spectrum ß-lactamase-producing gram-negative organisms. Compared to 2014, fewer hospitals perform active surveillance for MRSA and VRE. Overall, 90% of facilities used chlorhexidine gluconate bathing in all or select inpatients, and 53% used ultraviolet light or hydrogen peroxide vapor disinfection at discharge. Many respondents (44%) reported changes to contact precautions since COVID-19 that remain in place. CONCLUSIONS: Heterogeneity exists in the use of transmission-based precautions and adjunctive infection prevention measures aimed at reducing MDRO transmission. This variation reflects a need for updated and specific guidance, as well as further research on the use of contact precautions in healthcare facilities.

A Survey of Infection Prevention and Animal Assisted Activity Policies in Healthcare Facilities - United States, 2023.

In a survey of 104 U.S. infectious disease specialists, 88% reported working in facilities that allow Animal Assisted Activities or Pet Visitation. Variability existed in the species of animals allowed, restricted areas, and veterinary assessments, demonstrating a need to standardize infection prevention approaches across healthcare facilities to mitigate potential risks.

Nosocomial infections by diverse carbapenemase-producing Aeromonas hydrophila associated with combination of plumbing issues and heat waves.

BACKGROUND: Aquatic opportunistic pathogen Aeromonas hydrophila, known to persist in low-nutrient chlorinated waters, can cause life-threatening infections. Two intensive care units experienced a cluster of Aeromonas infections following outdoor temperature spikes coinciding with recurrent plumbing issues, with fatalities due to severe underlying comorbidities co-occurring with extensively-drug resistant (XDR) Aeromonas. METHODS: We investigated this cluster using whole genome sequencing to assess genetic relatedness of isolates and identify antimicrobial resistance determinants. Three A. hydrophila were isolated from patients staying in or adjacent to rooms with plumbing issues during or immediately after periods of elevated outdoor temperatures. Sinks and faucets were swabbed for culture. RESULTS: All A. hydrophila clinical isolates exhibited carbapenem resistance but were not genetically related. Diverse resistance determinants corresponding to extensively-drug resistant were found, including co-occurring KPC-3 and VIM-2, OXA-232, and chromosomal CphA-like carbapenemase genes, contributing to major treatment challenges. All 3 patients were treated with multiple antibiotic regimens to overcome various carbapenemase classes and expired due to underlying comorbidities. Environmental culture yielded no Aeromonas. CONCLUSIONS: While the investigation revealed no singular source of contamination, it supports a possible link between plumbing issues, elevated outdoor temperatures and incidence of nosocomial Aeromonas infections. The diversity of carbapenemase genes detected in these wastewater-derived Aeromonas warrants heightened infection prevention precautions during periods of plumbing problems especially with heat waves.

Performance of Clostridium difficile toxin enzyme immunoassay and nucleic acid amplification tests stratified by patient disease severity.

Many clinical laboratories in the United States are transitioning from toxin enzyme immunoassays (EIA) to nucleic acid amplification tests (NAATs) as the primary diagnostic test for Clostridium difficile infection (CDI). While it is known that the analytical sensitivity of the toxin EIA is poor, there are limited clinical data on the performance of these assays for patients with mild or severe CDI. Two hundred ninety-six hospital inpatients with diarrhea and clinical suspicion for CDI were tested prospectively by toxin EIA, by C. difficile NAAT, and with a reference standard toxigenic culture. Following completion of laboratory testing, retrospective chart reviews were performed to stratify patients into mild and severe disease groups based on clinical criteria using a standard point-based system. One hundred forty-three patients with CDI confirmed by toxigenic culture were evaluated in this study. Among the patients with mild CDI, 49% tested positive by toxin EIA and 98% tested positive by NAAT. Among patients with severe CDI, 58% tested positive by toxin EIA and 98% tested positive by NAAT. Increased CDI disease severity was not associated with an increased sensitivity of EIA (P = 0.31). These data demonstrate that toxin EIA performs poorly both for patients with severe CDI and for those with mild CDI and support the routine use of NAAT for the diagnosis of CDI. The presence of stool toxin measured by EIA does not correlate with disease severity.

Ciprofloxacin-resistant Aeromonas hydrophila cellulitis following leech therapy.

We report a case of surgical site infection with ciprofloxacin-resistant Aeromonas hydrophila following leech therapy. Antimicrobial and genetic analyses of leech and patient isolates demonstrated that the resistant isolates originated from the leech gut microbiota. These data suggest that ciprofloxacin monotherapy as a prophylaxis regimen prior to leech therapy may not be effective in preventing infection.

De novo daptomycin-nonsusceptible enterococcal infections.

Potential emergence of enterococcal daptomycin nonsusceptibility among patients with no prior exposure to daptomycin poses clinical and public health challenges. We found that development of infections with daptomycin-nonsusceptible enterococci in these patients could be associated with sporadic emergence and clonal spread.

Case-control study comparing de novo and daptomycin-exposed daptomycin-nonsusceptible Enterococcus infections.

Understanding factors associated with de novo daptomycin-nonsusceptible Enterococcus (DNSE) infections will aid in better understanding the mechanisms of daptomycin nonsusceptibility. We conducted a case-control study to compare patients with DNSE infections who were daptomycin treatment naïve (n = 9) and those with DNSE infections who had exposure to daptomycin (n = 13). Less frequent exposure to antimicrobials, increased susceptibility to nitrofurantoin and gentamicin, and shorter duration of hospitalization were associated with de novo DNSE infection, suggesting a potential community reservoir.

Cardiovascular implantable electronic device replacement infections and prevention: results from the REPLACE Registry.

BACKGROUND: Infection following cardiovascular implantable electronic device (CIED) replacement is a serious complication, and rates of infection have increased. Analysis of procedural and clinical data from device replacement procedures collected by the REPLACE Registry may provide insights into infection prevention strategies and outcomes. METHODS: We prospectively evaluated procedural complications in patients undergoing CIED replacement over 6 months from 72 U.S. sites. Major and minor infections were predefined and adjudicated by an independent blinded clinical events committee. Data regarding infection prevention strategies and infectious outcomes were analyzed for their potential relationships. RESULTS: A total of 1,744 patients were included in REPLACE. All patients received preoperative intravenous antibiotics and 68.7% received postoperative systemic antibiotic therapy. CIED infection developed in 22 patients (1.3%), of which 14 cases were major (0.8%, 95% confidence interval [CI] 0.4%-1.3%) and eight were minor (0.5%, 95% CI 0.2%-0.9%). Patients with infections were more likely to have had postoperative hematomas (five of 22 [22.7%] vs 17 of 1,722 [0.98%], P = 0.002). Participating sites experiencing infection rates >5% were more likely to use povidone-iodine for topical antisepsis, had lower implantation volume, and had patients with higher Charlson Comorbidity Index (2.79 vs 2.32, 95% CI for difference 0.08-0.86, P = 0.019). CONCLUSIONS: In this multicenter prospective study with 6 months of follow-up, infections associated with CIED replacements were surprisingly infrequent, possibly due to the use of preoperative antibiotics. Patients with infections were more likely to have had a postoperative hematoma, and sites with higher infection rates had sicker patients and lower overall procedural volume.

Prevalence and Factors Associated With Antigen Test Positivity Following SARS-CoV-2 Infection Among Health Care Workers in Los Angeles.

Surges of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections among health care workers (HCWs) have led to critical staffing shortages. From January 4 to February 4, 2022, we implemented a return-to-work antigen testing program for HCWs, and 870 HCWs participated. Antigen test positivity was 60.5% for those ≤5 days from symptom onset or positive polymerase chain reaction (PCR), and 47.4% were positive at day 7. Antigen positivity was associated with receiving a booster vaccination and being ≤6 days from symptom onset or PCR test, but not age or a symptomatic infection. Rapid antigen testing can be a useful tool to guide return-to-work and isolation precautions for HCWs following infection.

Case Report: Symptomatic Herpes Simplex Virus Type 2 and Monkeypox Coinfection in an Adult Male.

A 39-year-old man presented with a history of fatigue, malaise, and rash with varied morphology on his perianal region. Polymerase chain reaction testing of the lesions confirmed coinfection with monkeypox and herpes simplex virus type 2. We emphasize the difficulty in distinguishing between monkeypox virus and herpes simplex virus type 2 based on history and examination alone.