Bette Jensen

Changes in the Prevalence of Nasal Colonization with Staphylococcus aureus in the United States, 2001–2004

BACKGROUNDnStaphylococcus aureus is a common cause of infection, particularly in persons colonized by this organism. Virulent strains of methicillin-resistant S. aureus (MRSA) have emerged in the general community.nnnMETHODSnA nationally representative survey of nasal colonization with S. aureus was conducted from 2001 through 2004 as part of the National Health and Nutrition Examination Survey. MRSA isolates were identified by the oxacillin disk-diffusion method. The pulsed-field gel electrophoresis (PFGE) type was determined for all MRSA isolates. A t statistic was used to compare the prevalence of colonization across biennia and across population subgroups. Cofactors independently associated with colonization were determined with backward stepwise logistic modeling.nnnRESULTSnThe prevalence of colonization with S. aureus decreased from 32.4% in 2001-2002 to 28.6% in 2003-2004 (P < .01), whereas the prevalence of colonization with MRSA increased from 0.8% to 1.5% (P < .05). Colonization with MRSA was independently associated with healthcare exposure in males and with having been born in the United States, age > or =60 years, diabetes, and poverty in females. In 2003-2004, a total of 19.7% (95% confidence interval, 12.4%-28.8%) of MRSA-colonized persons carried a PFGE type associated with community transmission.nnnCONCLUSIONSnNasal colonization with MRSA has increased in the United States, despite an overall decrease in nasal colonization with S. aureus. PFGE types associated with community transmission only partially account for the increase in MRSA colonization.

High-Level Vancomycin-Resistant Staphylococcus aureus Isolates Associated with a Polymicrobial Biofilm

ABSTRACT Glycopeptides such as vancomycin are the treatment of choice for infections due to methicillin-resistant Staphylococcus aureus. This study describes the identification of high-level vancomycin-resistant S. aureus (VRSA) isolates in a polymicrobial biofilm within an indwelling nephrostomy tube in a patient in New York. S. aureus, Enterococcus faecalis, Enterococcus faecium, Micrococcus species, Morganella morganii, and Pseudomonas aeruginosa were isolated from the biofilm. For VRSA isolates, vancomycin MICs ranged from 32 to >128 μg/ml. VRSA isolates were also resistant to aminoglycosides, fluoroquinolones, macrolides, penicillin, and tetracycline but remained susceptible to chloramphenicol, linezolid, rifampin, and trimethoprim-sulfamethoxazole. The vanA gene was localized to a plasmid of ∼100 kb in VRSA and E. faecium isolates from the biofilm. Plasmid analysis revealed that the VRSA isolate acquired the 100-kb E. faecium plasmid, which was then maintained without integration into the MRSA plasmid. The tetracycline resistance genes tet(U) and tet(S), not previously detected in S. aureus isolates, were identified in the VRSA isolates. Additional resistance elements in the VRSA isolate included a multiresistance gene cluster, ermB-aadE-sat4-aphA-3, msrA (macrolide efflux), and the bifunctional aminoglycoside resistance gene aac(6′)-aph(2)-Ia. Multiple combinations of resistance genes among the various isolates of staphylococci and enterococci, including vanA, tet(S), and tet(U), illustrate the dynamic nature of gene acquisition and loss within and between bacterial species throughout the course of infection. The potential for interspecies transfer of antimicrobial resistance genes, including resistance to vancomycin, may be enhanced by the microenvironment of a biofilm.

Multistate Outbreak of Pseudomonas fluorescens Bloodstream Infection after Exposure to Contaminated Heparinized Saline Flush Prepared by a Compounding Pharmacy

BACKGROUNDnPharmaceutical compounding, the manipulation of ingredients to create a customized medication, is a widespread practice. In January 2005, the Centers for Disease Control and Prevention was notified of 4 cases of Pseudomonas fluorescens bacteremia that were traced to contaminated heparinized saline intravenous flush syringes prepared as a compounded medical product.nnnPATIENTS AND METHODSnWe reviewed medical records of symptomatic patients with P. fluorescens-positive cultures of blood specimens or sections of explanted catheters, reviewed the production process of syringes, performed syringe cultures, compared isolates by pulsed-field gel electrophoresis (PFGE), and examined catheters by scanning electron microscopy.nnnRESULTSnWe identified 80 patients in 6 states with P. fluorescens-positive cultures during December 2004-March 2006. Sixty-four patients (80%) had received a diagnosis of cancer. Seventy-four (99%) of 75 patients for whom information about catheter type was available had long-term indwelling catheters. Thirty-three (41%) of 80 cases were diagnosed 84-421 days after the patients last potential exposure to a contaminated flush (delayed-onset cases). Compared with patients with early infection onset, more patients with delayed infection onset had venous ports (100% versus 50%; P <.001). By PFGE, clinical isolates from 50 (98%) of 51 patients were related to isolates cultured from unopened syringes. Scanning electron microscopy of explanted catheters revealed biofilms containing organisms morphologically consistent with P. fluorescens.nnnCONCLUSIONnThis outbreak underscores important challenges in ensuring the safety of compounded pharmaceuticals and demonstrates the potential for substantially delayed infections after exposures to contaminated infusates. Exposures to compounded products should be considered when investigating outbreaks. Patients exposed to contaminated infusates require careful follow-up, because infections can occur long after exposure.

Multiphasic Approach Reveals Genetic Diversity of Environmental and Patient Isolates of Mycobacterium mucogenicum and Mycobacterium phocaicum Associated with an Outbreak of Bacteremias at a Texas Hospital

ABSTRACT Between March and May 2006, a Texas hospital identified five Mycobacterium mucogenicum bloodstream infections among hospitalized oncology patients using fluorescence high-performance liquid chromatography analysis of mycolic acids. Isolates from blood cultures were compared to 16 isolates from environmental sites or water associated with this ward. These isolates were further characterized by hsp65, 16S rRNA, and rpoB gene sequencing, hsp65 PCR restriction analysis, and molecular typing methods, including repetitive element PCR, random amplified polymorphic DNA PCR, and pulsed-field gel electrophoresis (PFGE) of large restriction fragments. Three of five patient isolates were confirmed as M. mucogenicum and were in a single cluster as determined by all identification and typing methods. The remaining two patient isolates were identified as different strains of Mycobacterium phocaicum by rpoB sequence analysis. One of these matched an environmental isolate from a swab of a hand shower in the patients room, while none of the clinical isolates of M. mucogenicum matched environmental strains. Among the other 15 environmental isolates, 11 were identified as M. mucogenicum and 4 as M. phocaicum strains, all of which were unrelated by typing methods. Although the 16S rRNA gene sequences matched for all 14 M. mucogenicum isolates, there were two each of the hsp65 and rpoB sequevars, seven PCR typing patterns, and 12 PFGE patterns. Among the seven M. phocaicum isolates were three 16S rRNA sequevars, two hsp65 sequevars, two rpoB sequevars, six PCR typing patterns, and six PFGE patterns. This outbreak represents the first case of catheter-associated bacteremia caused by M. phocaicum and the first report of clinical isolates from a U.S. hospital. The investigation highlights important differences in the available typing methods for mycobacteria and demonstrates the genetic diversity of these organisms even within narrow confines of time and space.

Fatal group C streptococcal infection due to transfusion of a bacterially contaminated pooled platelet unit despite routine bacterial culture screening

BACKGROUND: An elderly man with chronic myelomonocytic leukemia developed respiratory distress and died less than 48 hours after transfusion of a pool of eight whole blood–derived platelets (PLTs). Blood cultures from the recipient and cultures of remnants from the pooled PLT bag grew group C streptococci (GCS). An investigation was conducted to identify both the infections source and the reasons for the false‐negative screening result.

Outbreak of Serratia marcescens bloodstream and central nervous system infections after interventional pain management procedures.

ObjectivesTo determine the cause of an outbreak of Serratia marcescens infections in patients after interventional pain management procedures at an outpatient pain clinic. MethodsWe conducted a case-control study and collected clinical and environmental samples. ResultsWe identified 5 culture-confirmed case-patients and 2 presumptive case-patients who had no bacteria recovered from cultures. The 7 case-patients were compared with 28 controls who underwent procedures at the same clinic but did not develop symptoms of infection. All confirmed case-patients had S. marcescens bloodstream infections; 2 had concurrent S. marcescens central nervous system infections. Case-patients were more likely than controls to have procedures that used contrast solution or entered the epidural or intervertebral disc space (P≤0.01 for each). All S. marcescens clinical isolates were indistinguishable by pulsed-field gel electrophoresis. We did not isolate S. marcescens from medications or environmental samples; however, S. marcescens was shown to survive and grow in contrast solution that was experimentally contaminated for up to 30 days. Single-dose vials of medication, including contrast solution, were used for multiple procedures; multiple medications were accessed with a common needle and syringe. DiscussionThe findings of this investigation suggest contamination of a common medication, likely contrast solution, as the source of the outbreak. Practices, such as reusing single-dose medication vials and using a common needle and syringe to access multiple medications, could have led to contamination and propagation of S. marcescens and should be avoided in interventional pain management procedures.

Catheter-related polymicrobial bloodstream infections among pediatric bone marrow transplant outpatients--Atlanta, Georgia, 2007.

OBJECTIVEnTo identify risk factors for polymicrobial bloodstream infections (BSIs) in pediatric bone marrow transplant (BMT) outpatients attending a newly constructed clinic affiliated with a childrens hospital.nnnMETHODSnAll 30 outpatients treated at a new BMT clinic during September 10-21, 2007, were enrolled in a cohort study. The investigation included interviews, medical records review, observations, and bacterial culture and molecular typing of patient and environmental isolates. Data were analyzed using exact conditional logistic regression.nnnRESULTSnThirteen patients experienced BSIs caused by 16 different, predominantly gram-negative organisms. Presence of a tunneled catheter (odds ratio [OR], 19.9 [95% confidence interval {CI}, 2.4-infinity), catheter access (OR, 13.7 [95% CI, 1.8-infinity]), and flushing of a catheter with predrawn saline (OR, 12.9 [95% CI, 1.0-766.0]) were independently associated with BSI. The odds of experiencing a BSI increased by a factor of 16.8 with each additional injection of predrawn saline (95% CI, 1.8-827.0). Although no environmental source of pathogens was identified, interviews revealed breaches in recommended infection prevention practice and medication handling. Saline flush solutions were predrawn, and multiple doses were obtained from single-dose preservative-free vials to avoid delays in patient care.nnnCONCLUSIONnWe speculate that infection prevention challenges in the new clinic, combined with successive needle punctures of vials, facilitated extrinsic contamination and transmission of healthcare-associated pathogens. We recommend that preservative-free single-use vials not be punctured more than once. Use of single-use prefilled saline syringes might prevent multiuse of single-use saline vials. Storage of saline outside a medication supply system might be advisable. Before opening new clinic facilities, hospitals should consider conducting a mock patient flow exercise to identify infection control challenges.

Investigation of increased rates of isolation of Bacillus species.

BACKGROUNDnIn 2007-2008, several US hospitals reported summertime increases in the number of clinical blood cultures positive for Bacillus species, which are common environmental bacteria.nnnOBJECTIVEnTo investigate increased rates of isolation of Bacillus species from blood cultures, identify risk factors, and recommend control strategies.nnnDESIGNnSurvey and case-control study.nnnSETTINGnMultiple hospitals, including a cancer center.nnnMETHODSnWe surveyed 24 facilities that reported increases. We also conducted a field investigation at a hospital with a high rate, reviewing charts, collecting clinical and environmental isolates, and observing infection control procedures. A case-control study compared inpatient case patients who had any blood culture positive for Bacillus with unmatched control patients who had a blood culture with no growth during June-August 2008.nnnRESULTSnAmong surveyed facilities, mean monthly rates rose from 25 to a peak of 75 Bacillus-positive blood cultures per 10,000 blood cultures performed during the period June-August. At the hospital where the case-control investigation was conducted, for most case patients (75%), the Bacillus-positive blood cultures represented contamination or device colonization rather than infection. We enrolled 48 case patients and 48 control patients; in multivariate analysis, only central venous access device use was significantly associated with case status (odds ratio, 14.0; [Formula: see text]). Laboratory testing identified at least 12 different Bacillus species (non-anthracis) among the isolates. Observation of infection control procedures revealed variability in central line care and blood sample collection techniques.nnnCONCLUSIONSnPeriodic increases in the environmental load of Bacillus species may occur in hospitals. Our investigation indicated that at one facility, these increases likely represented a pseudo-outbreak of Bacillus species colonizing central venous lines or their accessories, such as needleless connector devices. Vigilant attention should be paid to infection control practices when collecting blood samples for culture, to minimize the risk of contamination by environmental microorganisms.

Outbreak of Pantoea agglomerans Bloodstream Infections at an Oncology Clinic-Illinois, 2012-2013.

OBJECTIVE To determine the source of a healthcare-associated outbreak of Pantoea agglomerans bloodstream infections. DESIGN Epidemiologic investigation of the outbreak. SETTING Oncology clinic (clinic A). METHODS Cases were defined as Pantoea isolation from blood or catheter tip cultures of clinic A patients during July 2012-May 2013. Clinic A medical charts and laboratory records were reviewed; infection prevention practices and the facilitys water system were evaluated. Environmental samples were collected for culture. Clinical and environmental P. agglomerans isolates were compared using pulsed-field gel electrophoresis. RESULTS Twelve cases were identified; median (range) age was 65 (41-78) years. All patients had malignant tumors and had received infusions at clinic A. Deficiencies in parenteral medication preparation and handling were identified (eg, placing infusates near sinks with potential for splash-back contamination). Facility inspection revealed substantial dead-end water piping and inadequate chlorine residual in tap water from multiple sinks, including the pharmacy clean room sink. P. agglomerans was isolated from composite surface swabs of 7 sinks and an ice machine; the pharmacy clean room sink isolate was indistinguishable by pulsed-field gel electrophoresis from 7 of 9 available patient isolates. CONCLUSIONS Exposure of locally prepared infusates to a contaminated pharmacy sink caused the outbreak. Improvements in parenteral medication preparation, including moving chemotherapy preparation offsite, along with terminal sink cleaning and water system remediation ended the outbreak. Greater awareness of recommended medication preparation and handling practices as well as further efforts to better define the contribution of contaminated sinks and plumbing deficiencies to healthcare-associated infections are needed. Infect Control Hosp Epidemiol 2017;38:314-319.