Machine Learning To Stratify Methicillin-Resistant Staphylococcus aureus Risk among Hospitalized Patients with Community-Acquired Pneumonia

Methicillin-resistant Staphylococcus aureus (MRSA) is an uncommon but serious cause of community-acquired pneumonia (CAP). A lack of validated MRSA CAP risk factors can result in overuse of empirical broad-spectrum antibiotics. We sought to develop robust models predicting the risk of MRSA CAP using machine learning using a population-based sample of hospitalized patients with CAP admitted to either a tertiary academic center or a community teaching hospital. Data were evaluated using a machine learning approach. Cases were CAP patients with MRSA isolated from blood or respiratory cultures within 72 h of admission; controls did not have MRSA CAP. The Classification Tree Analysis algorithm was used for model development. Model predictions were evaluated in sensitivity analyses. A total of 21 of 1,823 patients (1.2%) developed MRSA within 72 h of admission. MRSA risk was higher among patients admitted to the intensive care unit (ICU) in the first 24 h who required mechanical ventilation than among ICU patients who did not require ventilatory support (odds ratio [OR], 8.3; 95% confidence interval [CI], 2.4 to 32). MRSA risk was lower among patients admitted to ward units than among those admitted to the ICU (OR, 0.21; 95% CI, 0.07 to 0.56) and lower among ICU patients without a history of antibiotic use in the last 90 days than among ICU patients with antibiotic use in the last 90 days (OR, 0.03; 95% CI, 0.002 to 0.59). The final machine learning model was highly accurate (receiver operating characteristic [ROC] area = 0.775) in training and jackknife validity analyses. We identified a relatively simple machine learning model that predicted MRSA risk in hospitalized patients with CAP within 72 h postadmission.

Vancomycin-resistant Enterococcus outbreak in a pre- and post-cardiothoracic transplant population: Impact of discontinuing multidrug-resistant organism surveillance during the coronavirus disease 2019 pandemic

INTRODUCTION

Many institutions suspended surveillance and contact precautions for multidrug-resistant organisms (MDROs) at the outset of the coronavirus disease 2019 (COVID-19) pandemic due to a lack of resources. Once our institution reinstated surveillance in September 2020, a vancomycin-resistant Enterococcus (VRE) faecium outbreak was detected in the cardiothoracic transplant units, a population in which we had not previously detected outbreaks.

METHODS

An outbreak investigation was conducted using pulsed-field gel electrophoresis for strain typing and electronic medical record review to determine the clinical characteristics of involved patients. The infection prevention (IP) team convened a multidisciplinary process improvement team comprised of IP, cardiothoracic transplant nursing and medical leadership, environmental services, and the microbiology laboratory.

RESULTS

Between December 2020 and March 2021, the outbreak involved thirteen patients in the cardiothoracic transplant units, four index cases, and nine transmissions. Of the 13, seven (54%) were on the transplant service, including heart and lung transplant recipients, patients with ventricular assist devices, and a patient on extracorporeal membrane oxygenation as a bridge to lung transplantation. Four of 13 (31%) developed a clinical infection.

DISCUSSION

Cardiothoracic surgery/transplant patients may have a similar risk for VRE-associated morbidity as abdominal solid organ transplant and stem cell transplant patients, highlighting the need for aggressive outbreak management when VRE transmission is detected. Our experience demonstrates an unintended consequence of discontinuing MDRO surveillance in this population and highlights a need for education, monitoring, and reinforcement of foundational infection prevention measures to ensure optimal outcomes.

Coronavirus disease 2019 (COVID-19) vaccine intentions and uptake in a tertiary-care healthcare system: A longitudinal study

OBJECTIVES

Healthcare workers (HCWs) are a high-priority group for coronavirus disease 2019 (COVID-19) vaccination and serve as sources for public information. In this analysis, we assessed vaccine intentions, factors associated with intentions, and change in uptake over time in HCWs.

METHODS

A prospective cohort study of COVID-19 seroprevalence was conducted with HCWs in a large healthcare system in the Chicago area. Participants completed surveys from November 25, 2020, to January 9, 2021, and from April 24 to July 12, 2021, on COVID-19 exposures, diagnosis and symptoms, demographics, and vaccination status.

RESULTS

Of 4,180 HCWs who responded to a survey, 77.1% indicated that they intended to get the vaccine. In this group, 23.2% had already received at least 1 dose of the vaccine, 17.4% were unsure, and 5.5% reported that they would not get the vaccine. Factors associated with intention or vaccination were being exposed to clinical procedures (vs no procedures: adjusted odds ratio [AOR], 1.39; 95% confidence interval [CI], 1.16-1.65) and having a negative serology test for COVID-19 (vs no test: AOR, 1.46; 95% CI, 1.24-1.73). Nurses (vs physicians: AOR, 0.24; 95% CI, 0.17-0.33), non-Hispanic Black (vs Asians: AOR, 0.35; 95% CI, 0.21-0.59), and women (vs men: AOR, 0.38; 95% CI, 0.30-0.50) had lower odds of intention to get vaccinated. By 6-months follow-up, >90% of those who had previously been unsure were vaccinated, whereas 59.7% of those who previously reported no intention of getting vaccinated, were vaccinated.

CONCLUSIONS

COVID-19 vaccination in HCWs was high, but variability in vaccination intention exists. Targeted messaging coupled with vaccine mandates can support uptake.

Impact of early antimicrobial stewardship intervention in patients with positive blood cultures: results from a randomized comparative study: Impact of stewardship on BSI outcomes

BACKGROUND

Antimicrobial stewardship intervention (ASI) appears necessary to realize the full benefits of rapid diagnostic technologies in clinical practice. This study aimed to compare clinical outcomes between early ASI paired with MALDI-TOF compared to MALDI-TOF with standard of care (SOC) reporting in patients with positive blood cultures.

METHODS

Adult patients with positive blood cultures and organism speciation via MALDI-TOF admitted between 2/2015 and 9/2015 were randomized to ASI or SOC in a 1:1 fashion. Patients admitted for at least 48 hours following positive culture were included in analyses. ASI was defined as a clinical assessment by a stewardship team member with non-binding treatment recommendations offered to the primary team. The primary outcome was time to definitive therapy. Secondary outcomes included post-culture length of stay (LOS), time to first change in antibiotics, and in-hospital mortality.

RESULTS

A total of 149 patients were included in analyses (76 in the ASI group and 73 in the SOC group). ASI and SOC arms did not differ according to age, sex, comorbidities, or severity of illness. Gram-positive organisms were common in both SOC and ASI arms (74.0 vs 61.8%, p=0.11). Time-to-definitive therapy was reduced, on average, by 30.3 hours in the ASI group (71.6 vs. 41.3 hours, p=0.01). Hospital LOS following the first positive blood culture was significantly shorter in the ASI group (8.7 vs. 11.2 days, p=0.049).

CONCLUSIONS

ASI combined with MALDI-TOF reduced the time to definitive therapy, time to first change in antibiotics, and was associated with a shorter post-culture LOS.

Seroprevalence and Correlates of SARS-CoV-2 Antibodies in Health Care Workers in Chicago

Background

Identifying factors associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among health care workers (HCWs) may help health systems optimize SARS-CoV-2 infection control strategies.

Methods

We conducted a cross-sectional analysis of baseline data from the Northwestern HCW SARS-CoV-2 Serology Cohort Study. We used the Abbott Architect Nucleocapsid IgG assay to determine seropositivity. Logistic regression models (adjusted for demographics and self-reported community exposure to coronavirus disease 2019 [COVID-19]) were fit to quantify the associations between occupation group, health care delivery tasks, and community exposure and seropositive status.

Results

A total of 6510 HCWs, including 1794 nurses and 904 non-patient-facing administrators, participated. The majority were women (79.6%), 74.9% were White, 9.7% were Asian, 7.3% were Hispanic, and 3.1% were non-Hispanic Black. The crude prevalence of seropositivity was 4.8% (95% CI, 4.6%-5.2%). Seropositivity varied by race/ethnicity as well as age, ranging from 4.2% to 9.6%. Out-of-hospital exposure to COVID-19 occurred in 9.3% of HCWs, 15.0% (95% CI, 12.2%-18.1%) of whom were seropositive; those with family members diagnosed with COVID-19 had a seropositivity rate of 54% (95% CI, 44.2%-65.2%). Support service workers (10.4%; 95% CI, 4.6%-19.4%), medical assistants (10.1%; 95% CI, 5.5%-16.6%), and nurses (7.6%; 95% CI, 6.4%-9.0%) had significantly higher seropositivity rates than administrators (referent; 3.3%; 95% CI, 2.3%-4.4%). However, after adjustment, nursing was the only occupation group with a significantly higher odds (odds ratio, 1.9; 95% CI, 1.3-2.9) of seropositivity. Exposure to patients receiving high-flow oxygen therapy and hemodialysis was significantly associated with 45% and 57% higher odds for seropositive status, respectively.

Conclusions

HCWs are at risk for SARS-CoV-2 infection from longer-duration exposures to people infected with SARS-CoV-2 within health care settings and their communities of residence.

Multidrug resistant Aeromonas infection following medical leech therapy: A case report and development of a joint antimicrobial stewardship and infection prevention protocol

OBJECTIVE

Aeromonas sp. infections are a recognized complication of medical leech therapy (MLT). In patients requiring MLT, ciprofloxacin or trimethoprim-sulphamethoxazole are commonly used to prevent such nosocomial infections. After a patient at our institution developed a MLT-associated multi-drug resistant (MDR) Aeromonas infection, we developed and evaluated a joint antimicrobial stewardship and infection prevention protocol for MLT at our institution.

METHODS

We describe a case of a surgical site infection with MDR Aeromonas following MLT that was resistant to typically prescribed prophylactic antimicrobials, and development of a new leech culture protocol to proactively monitor for antimicrobial resistance among our institution's leech supply. We also report the rates of MLT-associated infections prior to and following implementation of this protocol and the antimicrobial susceptibility profiles detected in leech culture at our institution.

RESULTS

Between October 2014 and February 2018, 46 patients received MLT at our institution. Other than the case described in this report, no other instances of MLT-related infections were noted during this time period. Culture results from 22 leeches in six batches since February 2018 showed that all were susceptible to ciprofloxacin, TMP-SMX, and ceftriaxone. Since initiation of a leech culture protocol, no further cases of MLT-associated infections have been reported at our institution.

CONCLUSIONS

In light of increasing antimicrobial resistance and the potentially devastating consequences of MLT-associated infections, institutions offering MLT should be aware of these risks and ensure that protocols are in place to minimize infection risks for patients.

Antimicrobial Resistance

Antimicrobial resistance is developing rapidly and threatens to outstrip the rate at which new antimicrobials are introduced. Genetic recombination allows bacteria to rapidly disseminate genes encoding for antimicrobial resistance within and across species. Antimicrobial use creates a selective evolutionary pressure, which leads to further resistance. Antimicrobial stewardship, best use, and infection prevention are the most effective ways to slow the spread and development of antimicrobial resistance.

Measuring the impact of varying denominator definitions on standardized antibiotic consumption rates: implications for antimicrobial stewardship programmes

Objectives

To quantify the impact of varying the at-risk days definition on the overall report of at-risk days and on the calculated standardized consumption rates (SCRs) for piperacillin/tazobactam, amikacin, daptomycin and vancomycin.

Methods

Data were evaluated for two system hospitals, an 894 bed academic centre and a 114 bed community hospital. Aggregate inpatient antibiotic administration and occupancy data were extracted from electronic databases at the facility-wide level. Occupancy data were reported from admission-discharge-transfer systems. At-risk days were defined as hospital days present (DP), patient days (PD), persons present (PP) and billing days (BD). Inpatient antimicrobial days of therapy (DOT) across four major antimicrobial agents were used to calculate facility-wide SCRs using each denominator and were evaluated by least-squares regression and R2 values.

Results

Within the 894 bed academic hospital, the average monthly facility-wide days were 28 424, 22 198, 15 957 and 14 789 by the DP, PP, PD and BD definitions, respectively. Within the 114 bed community hospital, the average monthly facility-wide days were 5175, 3523 and 2816 by the DP, PP and PD definitions, respectively. Strong concordance was observed between facility-wide SCRs using the DP and PP definitions in both the academic (R2 = 0.99, y = 0.78x - 0.001) and community (R2 = 0.99, y = 0.68x - 0.03) centres across all four inpatient antibiotics evaluated. In an analysis of piperacillin/tazobactam SCRs, rates were over-predicted by 28%-93% at the facility-wide level across centres using alternative denominators.

Conclusions

We found that data source and definitions of at-risk denominator days meaningfully impact antibiotic SCRs. Centres should carefully consider these potential sources of variation when setting consumption benchmarks and internally evaluating use.

National Evaluation of Needlestick Events and Reporting Among Surgical Residents

BACKGROUND

Needlestick injuries pose significant health hazards; however, the nationwide frequency of needlesticks and reporting practices among surgical residents are unknown. The objectives of this study were to examine the rate and circumstances of self-reported needlestick events in US surgery residents, assess factors associated with needlestick injuries, evaluate reporting practices, and identify reporting barriers.

STUDY DESIGN

A survey administered after the American Board of Surgery In-Training Examination (January 2017) asked surgical residents how many times they experienced a needlestick during the last 6 months, circumstances of the most recent event, and reporting practices and barriers. Factors associated with needlestick events were examined using multivariable hierarchical regression models.

RESULTS

Among 7,395 resident survey respondents from all 260 US general surgery residency programs (99.3% response rate), 27.7% (n = 2,051) noted experiencing a needlestick event in the last 6 months. Most events occurred in the operating room (77.5%) and involved residents sticking themselves (76.2%), mostly with solid needles (84.7%). Self-reported factors underlying needlestick events included residents' own carelessness (48.8%) and feeling rushed (31.3%). Resident-level factors associated with self-reported needlestick events included senior residents (PGY5 29.9% vs PGY1 22.4%; odds ratio 1.66; 95% CI 1.41 to 1.96), female sex (31.9% vs male 25.2%; odds ratio 1.31; 95% CI 1.18 to 1.46), or frequently working more than 80 hours per week (odds ratio 1.42; 95% CI 1.20 to 1.68). More than one-fourth (28.7%) of residents did not report the needlestick event to employee health.

CONCLUSIONS

In this comprehensive national survey of surgical residents, needlesticks occurred frequently. Many needlestick events were not reported and numerous reporting barriers exist. These findings offer guidance in identifying opportunities to reduce needlesticks and encourage reporting of these potentially preventable injuries among trainees.

Successful treatment of a Candida auris intra-articular infection

A 78-year-old woman with a long-term ankle spacer with antibacterials developed an intra-articular Candida auris infection. Treatment with systemic antifungal therapy plus an amphotericin B moulded cement spacer was successful.

Correlation between hospital-level antibiotic consumption and incident health care facility-onset Clostridium difficile infection

BACKGROUND

The purpose of this single-center, ecologic study is to characterize the relationship between facility-wide (FacWide) antibiotic consumption and incident health care facility-onset Clostridium difficile infection (HO-CDI).

METHODS

FacWide antibiotic consumption and incident HO-CDI were tallied on a monthly basis and standardized, from January 2013 through April 2015. Spearman rank-order correlation coefficients were calculated using matched-months analysis and a 1-month delay. Regression analyses were performed, with P < .05 considered statistically significant.

RESULTS

FacWide analysis identified a matched-months correlation between ceftriaxone and HO-CDI (ρ = 0.44, P = .018). A unit of stem cell transplant recipients did not have significant correlation between carbapenems and HO-CDI in matched months (ρ = 0.37, P = .098), but a significant correlation was observed when a 1-month lag was applied (ρ = 0.54, P = .014).

DISCUSSION

Three statistically significant lag associations were observed between FacWide/unit-level antibiotic consumption and HO-CDI, and 1 statistically significant nonlagged association was observed FacWide. Antibiotic consumption may convey extended ward-level risk for incident CDI.

CONCLUSIONS

Consumption of antibiotic agents may have immediate and prolonged influence on incident CDI. Additional studies are needed to investigate the immediate and delayed associations between antibiotic consumption and C difficile colonization, infection, and transmission at the hospital level.

Evaluation of targeted antimicrobial prophylaxis for transrectal ultrasound guided prostate biopsy: a prospective cohort trial

Background

We evaluated the effectiveness of targeted antimicrobial prophylaxis in transrectal ultrasound guided prostate biopsy (TRUSP).

Methods

A prospective, non-randomized cohort study was conducted. Rectal swab cultures plated on non-selective blood agar and on selective MacConkey agar supplemented with ciprofloxacin identified ciprofloxacin-susceptible and –resistant gram-negative bacteria (CS-GNB and CR-GNB). Patients with CS-GNB received ciprofloxacin while those with CR-GNB received directed prophylaxis. Infectious complications were defined clinically and microbiologically within 30 days after TRUSP. Data were derived at 7 and 30 days post procedure by questionnaires and electronic medical records. We hypothesized that there would be no difference in the infectious outcomes among the CS and CR groups.

Results

From November 1, 2012 to March 31, 2015, 510 men completed the study; 430 (84.3%) had CS-GNB and 80 (15.7%) had CR-GNB. 484 (94.9%) completed the study per protocol, while 26 (5.1%) had an intention-to-treat (ITT) analysis. Of the 484, 475 (98.1%) had no infections, nine (1.9%) had infections, six of which (1.2%) were culture-proven (CP). The nine infections were as follows: five (1.0%) uncomplicated UTIs, one (0.2%) complicated UTI, and three (0.6%) urosepsis. One case of uncomplicated UTI and two cases of urosepsis were not CP, but were diagnosed clinically. ITT outcomes were similar. The infection rates were not statistically different between the CS-and CR-GNB patients (p-value = 0.314; 95% CI 0.8–3.3). The four patients with complicated UTIs or sepsis were hospitalized for a mean of 2.6 days and discharged without sequelae. Of the nine infections, three were antimicrobial prophylaxis failures (two ciprofloxacin and one amikacin); three were likely due to failure of the collection or processing of the rectal swab or increasing bacterial resistance between the time of swab collection and biopsy, and three developed clinical infections with no isolate recovered.

Conclusions

Targeted antimicrobial prophylaxis follows the principles of antimicrobial stewardship and achieved a low rate of infectious complications with limited morbidity and no sequelae. This individualized method of prophylaxis may be widely applied. Further studies are needed to explore reasons for targeted prophylaxis failure and to determine comparative efficacy of non-ciprofloxacin-containing targeted prophylaxis regimens.

Trial registration

ClinicalTrials.gov. NCT01659866. Registered 9 July 2012. First patient enrolled 1 November 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2470-1) contains supplementary material, which is available to authorized users.

Implementation of a cefazolin-based stewardship pathway for methicillin-susceptible Staphylococcus aureus bloodstream infections paired with infectious diseases consultation

Methicillin-susceptible Staphylococcus aureus (MSSA) infections have been successfully treated both with cefazolin and antistaphylococcal penicillins; cefazolin appears effective in MSSA bloodstream infections (BSIs). Thus, our antimicrobial stewardship programme (ASP) implemented a clinical pathway supporting cefazolin use in MSSA-BSIs and restricting oxacillin use to infectious diseases (ID) consultation due to cefazolin's lower cost and more convenient dosing. This before and after quasi-experimental study was conducted to describe the impact on outcomes and process of care measures associated with implementing this pathway among patients with MSSA-BSI. Definitive treatment with cefazolin increased over the study period from 17.3% to 69.8% post-implementation. Clinical failure (5.8% vs. 2.3%; P = 0.62) and in-hospital mortality (3.8% vs. 0%; P = 0.50) were rare pre- and post-implementation. Median hospital length of stay among survivors was similar between pre- and post-implementation periods (P = 0.31). Duration of bacteraemia [median (IQR) 3 (2-4) days vs. 2 (2-3) days; P = 0.002] and rates of re-infection after culture clearance (9.6% vs. 0%; P = 0.06) were reduced post-implementation. Frequency of source control (P = 0.71) and time to source control (P = 0.52) were similar between study periods. Significant increases in ID consultations (33.3% [3/9] vs. 73.3% [22/30]; P = 0.047) and median (IQR) 24-h daily doses [2 (1-3) g vs. 6 (3-6) g; P < 0.01] were seen for patients treated with cefazolin post-implementation. ASPs may find implementation of a similar pathway to be an effective means of improving the care of patients infected with MSSA.

Respiratory syncytial virus outbreak on an adult stem cell transplant unit

BACKGROUND

An increase in respiratory syncytial virus type B (RSV-B) infections was detected on an adult hematology/oncology and stem cell transplant unit during March 2015. This prompted an outbreak investigation.

METHODS

Nosocomial cases were defined as RSV-B-positive patients who developed respiratory virus symptoms ≥ 7 days after admission to the unit or were readmitted with symptoms ≤ 7 days since last discharge from the unit. Strict outbreak control measures were implemented to stop the outbreak.

RESULTS

During the outbreak, 19 cases of RSV-B were detected, 14 among patients and 5 among health care workers (HCWs). Additionally, 2 HCWs tested positive for respiratory syncytial virus type A and 1 tested positive for influenza B among the 27 symptomatic HCWs evaluated. No specific antiviral therapy was given and all cases recovered without progression to lower respiratory tract infection. After no new cases were identified for 2 weeks, the outbreak was declared over.

CONCLUSIONS

High vigilance for respiratory viruses on high-risk inpatient units is required for detection and prevention of potential outbreaks. Multiple respiratory viruses with outbreak potential were identified among HCWs. HCWs with respiratory virus symptoms should not provide direct patient care. Absence of lower respiratory tract infection suggests lower virulence of RSV-B, compared with respiratory syncytial virus type A, among immunocompromised adults.

Prolonged norovirus infection after pancreas transplantation: a case report and review of chronic norovirus

Norovirus is a major cause of self-limited gastroenteritis worldwide. Prevention and treatment are thwarted by rapid viral evolution, and thus supportive care remains the mainstay of therapy. Chronic infection in immunocompromised hosts is increasingly described. We report a case of norovirus infection lasting 2543 days in a pancreas transplant recipient. Serial fecal specimens were obtained, from which a map of genetic relatedness was derived. The clinical course was complicated by renal failure that progressed to end-stage renal disease. Minimization of immunosuppression was associated with resolution of the infection. Subsequently, the patient experienced a suspected allograft rejection that did not compromise pancreas function. The patient later underwent living-related renal transplantation without recurrence of enteritis.

Reducing catheter-associated urinary tract infections in a neuro-spine intensive care unit

A collaborative effort reduced catheter-associated urinary tract infections in the neuro-spine intensive care unit where the majority of infections occurred at our institution. Our stepwise approach included retrospective data review, daily rounding with clinicians, developing and implementing an action plan, conducting practice audits, and sharing of real-time data outcomes. The catheter-associated urinary tract infection rate was reduced from 8.18 to 0.93 per 1,000 catheter-days and standardized infection ratio decreased from 2.16 to 0.37.

Optimal timing of oral fosfomycin administration for pre-prostate biopsy prophylaxis

OBJECTIVES

As the optimal administration time for fosfomycin peri-procedural prophylaxis is unclear, we sought to determine optimal administration times for fosfomycin peri-procedural prophylaxis.

METHODS

Plasma, peripheral zone and transition zone fosfomycin concentrations were obtained from 26 subjects undergoing transurethral resection of the prostate (TURP), following a single oral dose of 3 g of fosfomycin. Population pharmacokinetic modelling was completed with the Nonparametric Adaptive Grid (NPAG) algorithm (Pmetrics package for R), with a four-compartment model. Plasma and tissue concentrations were simulated during the first 24 h post-dose, comparing these with EUCAST susceptibility breakpoints for Escherichia coli, a common uropathogen.

RESULTS

Non-compartmental-determined pharmacokinetic values in our population were similar to those reported in the package insert. Predicted plasma concentrations rapidly increased after the first hour, giving more than 90% population coverage for organisms with an MIC ≤4 mg/L over the first 12 h post-dose. Organisms with higher MICs fared much worse, with organisms at the EUCAST breakpoint being covered for <10% of the population at any time. Transitional zone prostate concentrations exceeded 4 mg/L for 90% of the population between hours 1 and 9. Peripheral zone prostate concentrations were much lower and only exceeded 4 mg/L for 70% of the population between hours 1 and 4.

CONCLUSIONS

Until more precise plasma and tissue data are available, we recommend that fosfomycin prophylaxis be given 1-4 h prior to prostate biopsy. We do not recommend fosfomycin prophylaxis for subjects with known organisms with MICs >4 mg/L.

Prospective Approach to Managing Antimicrobial Drug Shortages

Antimicrobial drug shortages continue to increase, with few new therapeutic options available. Nationally, proposals have been offered to alleviate drug shortages; however, these recommendations are unlikely to effect change in the near future. Thus, antimicrobial stewardship leaders in acute care hospitals must develop a prospective management strategy to lessen the impact of these shortages on patient care. Herein, we describe several resources available to aid professionals in antimicrobial stewardship and healthcare epidemiology to manage drug shortages. An effective approach should include prospectively tracking shortages and maximizing inventory by appropriately managing usage. Several tenets should underpin this management. Alternative agents should be rationally chosen before the inventory of the primary agent has reached zero, ethical considerations should be taken into account, and timely notification and communication with key stakeholders should occur throughout the prescribing and dispensing process.

Evaluation of Vitek MS for rapid classification of clinical isolates belonging to Mycobacterium avium complex

We evaluated the ability of the Vitek MS system to classify clinical pulmonary Mycobacterium avium complex isolates compared to multilocus sequence analysis. Vitek MS accurately identified 55% of the isolates as M. avium and 18% as M. intracellulare, but misidentified 24 (27%) Mycobacterium chimaera isolates as Mycobacterium intracellulare.

Host impairments in patients with neoplastic diseases

Healthy individuals possess an immune system comprising physical barriers, innate and acquired immunity as well as the indigenous microflora that populate the body surfaces. The immune system maintains constant vigilance over the body at the cellular level as well as at the interface between the host integument and the resident microflora. However, neoplastic diseases and their treatment often lead to impaired immunity resulting in an increased risk of infections due to viruses, bacteria, fungi, and protozoa. This chapter explores the various aspects of host impairment focusing on the components of immunity and the interplay between them to explain why it is that these patients succumb to infections per se. In so doing, we hope that the reader will be better equipped to understand the risks patients face so as to anticipate potential infectious complications and implement appropriate measures to help attain successful remission of the neoplastic diseases and maintain the best quality of life for the patient.

Respiratory infections

The respiratory tract is a common site of infection in cancer patients and is associated with substantial moribidity and mortality in this population. Cancer, chemotherapy, and radiation can all cause noninfectious pulmonary infiltrates and respiratory symptoms that can masquerade as a respiratory tract infection. Cancer patients are at a particular risk for infection by a wide variety of different viruses, fungi, and bacteria that can be difficult to treat. Although noninvasive diagnostics have significantly improved recently, patients with severe pneumonia and those not responding to usual therapy should be candidates for aggressive diagnostic testing and tissue sampling. Initial therapy should be carefully chosen and individually tailored to account for the individual patient's underlying risk factors for multi-drug-resistant pathogens, viral pathogens, or fungi. Once diagnostic testing returns, therapy should be altered to appropriately narrow the spectrum of coverage.

Epidemiology of infections in cancer patients

Although major advances in the care of cancer patients over the past several decades have resulted in improved survival, infectious complications remain a significant cause of morbidity and mortality. To successfully identify, treat, and prevent infections, a comprehensive understanding of risk factors that predispose to infection and of commonly encountered pathogens is necessary. In addition, clinicians must keep abreast of the changing epidemiology of infections in this population. As therapeutic modalities continue to evolve, as established pathogens become increasingly drug resistant, and as new pathogens are discovered, successful management of infections will continue to present challenges in the years to come.

Characterization of ciprofloxacin resistant Escherichia coli isolates among men undergoing evaluation for transrectal ultrasound guided prostate biopsy

PURPOSE

We determine the prevalence of ciprofloxacin resistant gram-negative bacilli in patients scheduled for transrectal ultrasound guided prostate biopsy, characterize the Escherichia coli strains recovered from this patient population, and characterize the mechanisms responsible for β-lactam and ciprofloxacin resistance.

MATERIALS AND METHODS

Rectal swabs from 991 patients were cultured for ciprofloxacin resistant gram-negative bacilli with a selective medium. Recovered E. coli isolates were further analyzed with susceptibility testing, pulsed field gel electrophoresis, plasmid isolation and sequencing.

RESULTS

A total of 193 ciprofloxacin resistant gram-negative bacilli were recovered and of these isolates 167 (87%) were E. coli. The prevalence of ciprofloxacin resistant E. coli in the study population was 17%. Only 38 (26%) of the 149 E. coli isolates that received susceptibility testing were susceptible to ampicillin and ampicillin-sulbactam. In select isolates transferrable plasmids carrying β-lactamase were responsible for the resistance to the β-lactam agents and other nonβ-lactam antimicrobials. Diverse combinations of gyrA and parC mutations associated with fluoroquinolone resistance were identified. Strain typing and plasmid typing indicated that the E. coli isolates did not share a common origin.

CONCLUSIONS

Of the patients in our study 17% carried ciprofloxacin resistant E. coli. Analysis of resistance mechanisms and plasmid analysis along with strain typing demonstrated that this patient population harbored organisms with heterogeneous phenotypic susceptibility, indicating that universal prophylaxis would not provide optimal coverage for patients undergoing transrectal ultrasound guided prostate biopsy.

Monitoring seasonal influenza A evolution: rapid 2009 pandemic H1N1 surveillance with an reverse transcription-polymerase chain reaction/electro-spray ionization mass spectrometry assay

BACKGROUND

The emergence of the pandemic H1N1 influenza strain in 2009 reinforced the need for improved influenza surveillance efforts. A previously described influenza typing assay that utilizes RT-PCR coupled to electro-spray ionization mass spectrometry (ESI-MS) played an early role in the discovery of the pandemic H1N1 influenza strain, and has potential application for monitoring viral genetic diversity in ongoing influenza surveillance efforts.

OBJECTIVES

To determine the analytical sensitivity of RT-PCR/ESI-MS influenza typing assay for identifying the pandemic H1N1 strain and describe its ability to assess viral genetic diversity.

STUDY DESIGN

Two sets of pandemic H1N1 samples, 190 collected between April and June of 2009, and 69 collected between October 2009 and January 2010, were processed by the RT-PCR/ESI-MS influenza typing assay, and the spectral results were compared to reference laboratory results and historical sequencing data from the Nucleotide Database of the National Center for Biotechnology Information (NCBI).

RESULTS

Strain typing concordance with reference standard testing was 100% in both sample sets, and the assay demonstrated a significant increase in influenza genetic diversity, from 10.5% non-wildtype genotypes in early samples to 69.9% in late samples (P<0.001). An NCBI search demonstrated a similar increase, from 13.4% to 45.2% (P<0.001).

CONCLUSIONS

This comparison of early versus late influenza samples analyzed by RT-PCR/ESI-MS demonstrates the influenza typing assay's ability as a universal influenza detection platform to provide high-fidelity pH1N1 strain identification over time, despite increasing genetic diversity in the circulating virus. The genotyping data can also be leveraged for high-throughput influenza surveillance.

Targeted antimicrobial prophylaxis using rectal swab cultures in men undergoing transrectal ultrasound guided prostate biopsy is associated with reduced incidence of postoperative infectious complications and cost of care

PURPOSE

We evaluated targeted antimicrobial prophylaxis in men undergoing transrectal ultrasound guided prostate biopsy based on rectal swab culture results.

MATERIALS AND METHODS

From July 2010 to March 2011 we studied differences in infectious complications in men who received targeted vs standard empirical ciprofloxacin prophylaxis before transrectal ultrasound guided prostate biopsy. Targeted prophylaxis used rectal swab cultures plated on selective media containing ciprofloxacin to identify fluoroquinolone resistant bacteria. Patients with fluoroquinolone susceptible organisms received ciprofloxacin while those with fluoroquinolone resistant organisms received directed antimicrobial prophylaxis. We identified men with infectious complications within 30 days after transrectal ultrasound guided prostate biopsy using the electronic medical record.

RESULTS

A total of 457 men underwent transrectal ultrasound guided prostate biopsy, and of these men 112 (24.5%) had rectal swab obtained while 345 (75.5%) did not. Among those who received targeted prophylaxis 22 (19.6%) men had fluoroquinolone resistant organisms. There were no infectious complications in the 112 men who received targeted antimicrobial prophylaxis, while there were 9 cases (including 1 of sepsis) among the 345 on empirical therapy (p=0.12). Fluoroquinolone resistant organisms caused 7 of these infections. The total cost of managing infectious complications in patients in the empirical group was $13,219. The calculated cost of targeted vs empirical prophylaxis per 100 men undergoing transrectal ultrasound guided prostate biopsy was $1,346 vs $5,598, respectively. Cost-effectiveness analysis revealed that targeted prophylaxis yielded a cost savings of $4,499 per post-transrectal ultrasound guided prostate biopsy infectious complication averted. Per estimation, 38 men would need to undergo rectal swab before transrectal ultrasound guided prostate biopsy to prevent 1 infectious complication.

CONCLUSIONS

Targeted antimicrobial prophylaxis was associated with a notable decrease in the incidence of infectious complications after transrectal ultrasound guided prostate biopsy caused by fluoroquinolone resistant organisms as well as a decrease in the overall cost of care.

The impact of anti-infective drug shortages on hospitals in the United States: trends and causes

Anti-infective shortages pose significant logistical and clinical challenges to hospitals and may be considered a public health emergency. Anti-infectives often represent irreplaceable life-saving treatments. Furthermore, few new agents are available to treat increasingly prevalent multidrug-resistant pathogens. Frequent anti-infective shortages have substantially altered patient care and may lead to inferior patient outcomes. Because many of the shortages stem from problems with manufacturing and distribution, federal legislation has been introduced but not yet enacted to provide oversight for the adequate supply of critical medications. At the local level, hospitals should develop strategies to anticipate the impact and extent of shortages, to identify therapeutic alternatives, and to mitigate potential adverse outcomes. Here we describe the scope of recent anti-infective shortages in the United States and explore the reasons for inadequate drug supply.

Idiopathic pontine Streptococcus salivarius abscess in an immunocompetent patient: management lessons through case illustration and literature review

A 55-y-old woman with no previous medical history presented with a 3-day history of progressive headache, nausea, emesis, right-sided facial numbness, and right-sided extremity weakness. Serial magnetic resonance imaging demonstrated rapid enlargement of a left-sided ring-enhancing dorsal pontine lesion with an exophytic portion, raising concern for an abscess. A stereotactically guided left-sided retrosigmoid craniotomy for abscess incision and decompression was performed given the rapid progression of her neurological deficits. Streptococcus salivarius was isolated from the intra-operative samples. After an extensive evaluation, no source for the S. salivarius was identified. Solitary brainstem abscesses are uncommon intracranial infections with high morbidity and mortality. Patients can present with non-specific symptoms and often have no previous medical history. Since 1974, 40 patients with solitary brainstem abscess have survived to hospital discharge. We outline management strategies for solitary brainstem abscess based on a literature review of survivors.

Effects of mumps outbreak in hospital, Chicago, Illinois, USA, 2006

Controlling the outbreak cost 4 times more than a routine prevention program.

In 2006, nearly 6,000 mumps cases were reported in the United States, 795 of which occurred in Illinois. In Chicago, 1 healthcare institution experienced ongoing transmission for 4 weeks. This study examines the outbreak epidemiology and quantifies the financial affect on this organization. This retrospective cohort study was conducted through case and exposure identification, interviews, medical record reviews, and immunologic testing of blood specimens. Nine mumps cases resulted in 339 exposures, 325 (98%) among employees. During initial investigation, 186 (57%) of the exposed employees had evidence of mumps immunity. Physicians made up the largest group of noncompliers (55%) with mumps immunity testing. The cost to the institution was $262,788 or $29,199 per mumps case. The outbreak resulted in substantial staffing and financial challenges for the institution that may have been minimized with readily accessible electronic employee vaccination records and adherence to infection control recommendations.

Carbapenem-resistant Acinetobacter baumannii infections after organ transplantation

Multi-drug resistant (MDR) gram-negative infections among solid organ transplant (SOT) recipients have long been associated with high morbidity and mortality. Acinetobacter baumannii has emerged as a potent nosocomial pathogen with the recent acquisition of resistance to broad-spectrum beta-lactams, aminoglycosides, fluoroquinolones, and most notably, carbapenems. Despite a national rise in carbapenem-resistant A. baumannii (CRAB) infections, outcomes among SOT recipients with this emerging MDR pathogen are largely unknown. This single-center cohort is the first to describe the characteristics, complications, and outcomes among abdominal organ transplant recipients with CRAB. The current study suggests that SOT patients with CRAB suffer from prolonged hospitalization, infection with other MDR organisms, allograft dysfunction and loss, and high overall infection-related mortality.

Persistent Staphylococcus aureus bacteremia: an analysis of risk factors and outcomes

BACKGROUND

Persistent Staphylococcus aureus bacteremia (pSAB) is an emerging problem among hospitalized patients. We studied key clinical characteristics and outcomes associated with pSAB to better define the epidemiological features of this increasingly recognized clinical entity.

METHODS

A retrospective case-control study of patients hospitalized with SAB between January 1, 2001, and September 30, 2004, was conducted to compare the clinical characteristics, management, and outcomes of patients with pSAB (> 7 days of bacteremia) with those of a cohort of patients with nonpersistent SAB (< 3 days of bacteremia). Patients with 4 to 6 days of bacteremia were excluded from the analysis. To detect a potential association between reduced susceptibility to vancomycin and persistent methicillin-resistant SAB, vancomycin susceptibilities were confirmed using standard dilution methods.

RESULTS

Eighty-four patients with pSAB and 152 patients with nonpersistent SAB were included in the analysis. Methicillin resistance (odds ratio [OR], 5.22; 95% confidence interval [CI], 2.63-10.38), intravascular catheter or other foreign body use (OR, 2.37; 95% CI, 1.11-3.96), chronic renal failure (OR, 2.08; 95% CI, 1.09-3.96), more than 2 sites of infection (OR, 3.31; 95% CI, 1.17-9.38), and infective endocarditis (OR, 10.30; 95% CI, 2.98-35.64) were independently associated with pSAB. The mean time to device removal was significantly longer in patients with pSAB than in patients with nonpersistent SAB (4.94 vs 1.64 days; P < .01). There was no evidence of reduced vancomycin susceptibility among persistent methicillin-resistant S aureus isolates. Clinical outcomes were significantly worse among patients with pSAB.

CONCLUSIONS

Many hospitalized patients may be at risk for pSAB. Aggressive attempts to minimize the risk of complications and poor outcomes associated with pSAB, such as early device removal, should be encouraged.

Early onset of tenofovir-induced renal failure: case report and review of the literature

Tenofovir is an acyclic nucleotide analogue reverse transcriptase inhibitor that is commonly prescribed as part of a highly active antiretroviral therapy (HAART) regimen in HIV-infected patients. Although it is generally well tolerated, renal insufficiency has been associated with its use. We report a biopsy-proven case of acute renal failure that developed within weeks of initiating a HAART regimen containing tenofovir, and review the literature with specific attention to cases of renal failure occurring within 8 weeks of tenofovir initiation. Our patient developed renal insufficiency within 3 weeks of initiating tenofovir-containing HAART and overt renal failure was noted within 5 weeks. Renal biopsy demonstrated histopathologic changes suggestive of HIV nephropathy, despite normal baseline serum creatinine values. Thirty additional cases of tenofovir-associated renal failure have been reported. In the majority (n = 22, 73%), renal failure occurred months after initiating therapy (range: 5-26 months). However, in a significant subset (n = 8, 27%), renal failure occurred within 8 weeks of treatment initiation. Our data suggest that some patients are at risk for developing renal failure within weeks of tenofovir initiation. Thorough evaluation of renal function should be undertaken before prescription of tenofovir-containing HAART. For those in whom subclinical renal disease is discerned, added vigilance when monitoring renal function may be warranted.

Improving the assessment of vancomycin-resistant enterococci by routine screening

BACKGROUND

As infection with vancomycin-resistant enterococci (VRE) increases in hospitals, knowledge about VRE reservoirs and improved accuracy of epidemiologic measures are needed. Many assessments underestimate incidence by including prevalent carriers in at-risk populations. Routine surveillance cultures can substantially improve prevalence and incidence estimates, and assessing the range of improvement across diverse units is important.

METHODS

We performed a retrospective cohort study using accurate at-risk populations to evaluate the range of benefit of admission and weekly surveillance cultures in detecting unrecognized VRE in 14 patient-care units.

RESULTS

We assessed 165 unit-months. The admission prevalence of VRE was 2.2%-27.2%, with admission surveillance providing 2.2-17-fold increased detection. Medical units were significantly more likely to admit VRE carriers than were surgical units. Monthly incidence was 0.8%-9.7%, with weekly surveillance providing 3.3-15.4-fold increased detection. The common practice of reporting incidence using the total number of patients, rather than patients at risk, underestimated incidence by one-third. Overall, routine surveillance prevented the misclassification of 43.0% (unit range, 0%-85.7%) of "incident" carriers on the basis of clinical cultures alone and increased VRE precaution days by 2.4-fold (unit range, 2.0-2.6-fold).

CONCLUSIONS

Routine surveillance markedly increases the detection of VRE, despite variability across patient-care units. Correct denominators prevent the substantial underestimation of incidence.

The clinical impact of linezolid susceptibility reporting in patients with vancomycin-resistant enterococci

Linezolid remains a mainstay of therapy for vancomycin-resistant enterococci (VREs), but resistance has emerged. We describe a cohort of 20 patients with linezolid-intermediate or resistant VRE (LIRVRE) reported by Etest and disk diffusion testing, 18 of whom demonstrated linezolid susceptibility by agar dilution on further investigation. Patients with reported LIRVRE were matched based on culture site and enterococcal species to patients with linezolid-susceptible VRE (LSVRE) in a 1:3 ratio. Patients with reported LIRVRE developed more nosocomial infections (P = .04), had more central lines placed (P = .04), and underwent more computed tomography scans related to VRE infection (P = .02). Multivariate analysis revealed increased surgical procedures related to VRE infections (P = .008), increased linezolid use during hospital stay (P = .03), and delayed culture and susceptibility results compared with those with LSVRE (P = .006). Therefore, inaccurate detection and reporting of LIRVRE by disk diffusion and Etest is associated with increased patient morbidity and resource use.

Peritoneal fluid penetration of tigecycline

OBJECTIVE

To describe the peritoneal fluid penetration of tigecycline.

CASE SUMMARY

A 33-year-old critically ill man who had undergone orthotopic liver and cadaveric renal transplant presented with sepsis. The patient required empiric antimicrobial coverage, continuous veno-venous hemofiltration, prolonged mechanical ventilation, tracheostomy placement, and maintenance immunosuppressive therapy. After multiple infections with multi-drug resistant pathogens, the patient developed vancomycin-resistant Enterococcus faecium peritonitis. Tigecycline 50 mg was administered every 12 hours, and ascites fluid drug concentrations were obtained. Drug concentrations in the peritoneal fluid were determined by high-performance liquid chromatography and revealed a tigecycline concentration of 0.074 microg/mL. Despite aggressive measures, the patient's condition continued to decline; he died 2 weeks after tigecycline initiation.

DISCUSSION

As of October 3, 2006, these are the first data to describe tigecycline peritoneal fluid penetration. Tigecycline was aggressively administered at twice the recommended dosage for overt liver failure in light of the severity of this patient's condition. A tigecycline peritoneal fluid concentration of 44-54% of serum concentration was calculated based on the patient's peritoneal fluid drug concentration and previously published serum concentrations from a similar population.

CONCLUSIONS

Peritoneal penetration of tigecycline was approximately 50% in this critically ill patient. Establishment of site-specific breakpoints for tigecycline may be necessary. Future studies will need to evaluate the penetration of tigecycline into peritoneal fluid and other tissues.

Vancomycin and home health care

Microbiologic diagnosis before hospital discharge and physician education may limit inappropriate vancomycin use in homecare patients.

The Hospital Infection Control Practices Advisory Committee published guidelines for prudent use of vancomycin to combat increasing resistance to antimicrobial drugs. Studies examining compliance with these guidelines primarily involve hospitalized patients. The growing practice of home use of antimicrobial drugs led to this retrospective cohort study that evaluated parenteral vancomycin use in patients receiving it through a homecare agency. We found that 39.2% of outpatients received vancomycin outside the guidelines, mainly because of prolonged empiric therapy, dosing convenience, and prolonged use after surgery. Patients were more likely to receive vancomycin appropriately if they were >65 years of age, had a history of malignancy, or were discharged from a medical service. In addition, obtaining wound cultures and attempting a microbiologic diagnosis led to more appropriate vancomycin use. Recommendations for prudent vancomycin use are often overlooked when selecting antimicrobial drugs for home infusion. The public health impact of this practice remains unknown.

Cavitary Legionella pneumonia in a liver transplant recipient

This report describes the clinical course of a liver transplant recipient in whom cavitary pneumonia developed due to Legionella pneumophila. We review the experience with cavitary pulmonary processes caused by Legionella species in liver allograft recipients and describe the diagnostic microbiology of this organism. The clinical course of this patient demonstrates the importance of considering legionellosis in the differential diagnosis of lung abscesses after liver transplantation and the diagnostic difficulties encountered with this bacterium.

Influence of role models and hospital design on hand hygiene of healthcare workers

We assessed the effect of medical staff role models and the number of health-care worker sinks on hand-hygiene compliance before and after construction of a new hospital designed for increased access to handwashing sinks. We observed health-care worker hand hygiene in four nursing units that provided similar patient care in both the old and new hospitals: medical and surgical intensive care, hematology/oncology, and solid organ transplant units. Of 721 hand-hygiene opportunities, 304 (42%) were observed in the old hospital and 417 (58%) in the new hospital. Hand-hygiene compliance was significantly better in the old hospital (161/304; 53%) compared to the new hospital (97/417; 23.3%) (p<0.001). Health-care workers in a room with a senior (e.g., higher ranking) medical staff person or peer who did not wash hands were significantly less likely to wash their own hands (odds ratio 0.2; confidence interval 0.1 to 0.5); p<0.001). Our results suggest that health-care worker hand-hygiene compliance is influenced significantly by the behavior of other health-care workers. An increased number of hand-washing sinks, as a sole measure, did not increase hand-hygiene compliance.

The incidence of antimicrobial allergies in hospitalized patients: implications regarding prescribing patterns and emerging bacterial resistance

BACKGROUND

The development of antimicrobial guidelines is one way in which institutions attempt to control emerging resistance, but the real challenge falls on promoting and ensuring adherence to these guidelines. Investigating reasons for the prescribing of alternative antimicrobial agents outside of these guidelines is crucial for modifying practices that may adversely impact institutional antimicrobial goals.

METHODS

Retrospective cross-referencing of computerized pharmacy printouts and concurrent manual medical record review.

RESULTS

Approximately 25% (470/1893) of the patients requiring antimicrobial therapy reported an allergy to at least 1 antimicrobial agent. The most commonly reported antimicrobial allergy was penicillin (295/1893 [15.6%]). Eighty-five patients (18.1%) reported having an allergy to 2 or more antimicrobial agents. Only 4% (27/601) of the reported antimicrobial allergies contained documentation as to the nature of the specific allergic reactions, while a manual medical record review revealed that 32% (23/73) of the antimicrobial allergies contained documentation of the specific allergic reaction. Ninety-eight (39. 7%) of 247 patients reporting an allergy only to penicillin and/or cephalosporin received vancomycin in comparison with 247 (17.4%) of 1423 patients without any antimicrobial allergies (P<.001). Similarly, 53 (21.5%) of 247 patients with reported penicillin and/or cephalosporin allergies received levofloxacin compared with 114 (8.0%) of 1423 patients without any antimicrobial allergy (P<. 001).

CONCLUSION

The incidence of penicillin allergy at our institution exceeds population averages. This finding, in combination with limited documentation of drug allergies, appears to lead to the prescribing of alternative antimicrobial agents that do not fit into institutional antimicrobial guidelines and, in some instances, may put the patient at risk for infection and/or colonization with resistant organisms. Use of these alternative agents may adversely impact the ability to manage emerging antimicrobial resistance.

The utility of aminoglycosides in an era of emerging drug resistance

As the problem of global antibiotic resistance continues to worsen, aminoglycosides have assumed increasing importance in clinical practice. Their broad antimicrobial spectrum, rapid bactericidal action, and ability to act synergistically with other drugs have made them especially useful in the treatment of serious nosocomial infections. However, as with other drugs, their overuse and misuse leads to the development of resistance in important microbial pathogens. The appropriate use of the aminoglycosides is essential to assure their continued efficacy. Therefore, physicians must familiarize themselves with both the clinical indications and the limitations of these drugs if they are to remain efficacious in the years to come.