Coralia N. Mihu

Incidence of fluoroquinolone-resistant and extended-spectrum β-lactamase-producing escherichia coli at a comprehensive cancer center in the United States

Background: Quinolones are used extensively for prophylaxis in high-risk cancer patients; however, increasing quinolone resistance is being reported. Extended-spectrum β-lactamase (ESBL)-producing E. coli may be associated with increased morbidity and mortality particularly in neutropenic cancer patients. Methods: We conducted a retrospective study of consecutive E. coli isolates from January 2009 to August 2009 at our institution. Data on antimicrobial susceptibility of E. coli isolates to commonly used antimicrobial agents and the frequency of ESBL production and fluoroquinolone resistance were gathered based on CLSI guidelines. Results: There were 443 isolates of E. coli recovered. The majority were from urine cultures (308 isolates, 69.5%). Forty-one (9.2%) isolates were ESBL producing. Nine (18.3%) of the 49 isolates recovered from blood stream infections were ESBL producing. Quinolone resistance was present in 204 isolates (46%). Carbapenems and aminoglycosides retained excellent activity. E. coli resistance to quinolones increasedfrom 13 to 46% in a period of 13 years (p = 0.001). Conclusion: The incidence of resistance to quinolones at our center may be increasing as a consequence of widespread use of quinolones as prophylaxis for neutropenic patients. ESBL-producing E. coli are frequent at our center and are associated with blood stream infections.

Does combination of lipid formulation of amphotericin B and echinocandins improve outcome of invasive aspergillosis in hematological malignancy patients

In vitro and in vivo studies suggested that combination of lipid formulation of amphotericin B (L‐AMB) and echinocandins may have a synergistic or additive effect against Aspergillus. Furthermore, clinical studies suggested that this combination may improve response of invasive aspergillosis (IA).

Risk factors and attributable mortality of late aspergillosis after T-cell depleted hematopoietic stem cell transplantation.

Abstract: Aim. Invasive aspergillosis occurs in 5–15% of allogeneic hematopoietic stem cell transplant (HSCT) recipients. Through the 1990s there has been an increase in the incidence of late aspergillosis (LA). We report on the incidence, risk factors, and attributable mortality of LA in a cohort of 398 adult and pediatric patients at Memorial Sloan‐Kettering Cancer Center from January 1999 through December 2003.

Work-up for infectious diarrhea after allogeneic hematopoietic stem cell transplantation : single specimen testing results in cost savings without compromising diagnostic yield

Abstract: Background. Diarrhea is a common complication of allogeneic bone marrow transplantation. Microbiologic stool studies are frequently ordered to rule out infectious etiology. The utility of examining multiple stool specimens per diarrheal episode has not been examined.

Risk factors for late Staphylococcus aureus bacteremia after allogeneic hematopoietic stem cell transplantation: a single-institution, nested case-controlled study.

We report on the incidence, risk factors, and outcome of late Staphylococcus aureus bacteremia (SAB) in a cohort of 709 adult and pediatric patients at Memorial Sloan-Kettering Cancer Center between September 1999 and December 2006. The SAB cases were identified by prospective surveillance and examination of a computerized database. Late SAB was defined as SAB occurring > 50 days post-hematopoietic stem cell transplantation (HSCT). A nested case-controlled study was conducted to identify predictors of late SAB. The incidence of late SAB was 6/100,000 patient-days. The median time from stem cell infusion to incident blood culture was 137 days (range, 55 to 581 days). Eighty-four percent of the cases were community acquired; 40% involved a focal infection. Bacteremia was persistent (>3 days) despite removal of endovascular access in > 50% of cases. Risk factors for late SAB were acute graft-versus-host disease (aGVHD) flare, acute or chronic skin GVHD (cGVHD), corticosteroid use, liver dysfunction, and prolonged hospital length of stay (LOS) post-HSCT. In multivariate models, skin GVHD (P = .002) and LOS (P = .02) remained significant. The median survival post-SAB was 135 days (range, 1 to 1765 days). Late SAB occurred mainly in the setting of GVHD or corticosteroid therapy. Clinical manifestations were highly variable. Multiple comorbidities, indicated by organ dysfunction and hospitalization, likely contributed to persistence and increased morbidity and mortality. We recommend a high index of suspicion and empiric antistaphylococcal treatment pending culture results in high-risk patients undergoing HSCT.

Hematologic safety profile of linezolid in the early periengraftment period after allogeneic stem cell transplantation.

Vancomycin-resistant enterococci (VRE) are common pathogens of bloodstream infections in the peritransplantation period. Linezolid is approved by the FDA for treating VRE infections, but has been associated with low rates of hematologic toxicity in the general population; thus, there are concerns about its potential myelotoxicity in the allogeneic hematopoietic stem cell transplantation (HSCT) setting. We examined the impact of linezolid treatment on the times to neutrophil and platelet engraftment in 33 patients who underwent HSCT. In this retrospective case-controlled study conducted from 2000 through 2007, cases received > or = 7 consecutive days of linezolid therapy, starting before day +8 post-HSCT. Controls received > or = 7 consecutive days of vancomycin therapy before day +8 and were matched to cases by age and conditioning regimen. The cumulative incidence function was used to estimate the probabilities for the times to neutrophil and platelet engraftment. A competing-risk regression model was used to determine whether times to engraftment differed for cases and controls. A total of 33 cases were compared with 33 controls. The median duration of treatment after stem cell infusion was 14 days (range, 7 to 34 days) for linezolid and 16 days (range, 8 to 33 days) for vancomycin. The rates of neutrophil and platelet engraftment were similar between the cases and controls. After adjusting for baseline characteristics, no difference in the times to neutrophil or platelet engraftment was seen between the 2 groups. Our findings demonstrate no adverse effect on the times to neutrophil or platelet engraftment with linezolid use. Larger prospective studies are needed to fully determine the hematologic safety of linezolid in patients undergoing HSCT.

Escherichia coli resistance to quinolones at a comprehensive cancer center

As part of Meropenem Yearly Susceptibility Test Information Collection/USA Surveillance Programme, we monitored the occurrence of quinolone resistance in Escherichia coli over a 10-year period. A total of 271 E. coli isolates from our institution were tested over a 10-year period. Screening for quinolone resistance (qnr) gene was performed. A decline in susceptibility of E. coli isolates to quinolones and aminoglycosides was noted over the 10-year span (P < 0.0001), which was significantly reduced compared with the average susceptibility of all sites. Introduction of quinolone prophylaxis has led to a significant decline in susceptibility of E. coli to all quinolones. The organisms remain susceptible to carbapenems, cefepime, and piperacillin/tazobactam. Periodic surveillance allows for detection of resistance patterns and adjustment of empiric antibiotic choice in patients at high risk for infection.

Current microbiology of percutaneous endoscopic gastrostomy tube (PEG tube) insertion site infections in patients with cancer

PurposePercutaneous endoscopic gastrostomy (PEG) is frequently used to provide enteral access in cancer patients who are unable to swallow. Infection is an important complication in this setting. Current microbiological data are needed to guide infection prevention and treatment strategies.MethodsThe microbiological records of our institution (a 550-bed comprehensive cancer center) were retrospectively reviewed over an 8-month study period in order to identify patients who developed PEG tube insertion site infections, and review their microbiological details and susceptibility/resistance data.ResultsFifty-eight episodes of PEG tube insertion site infections were identified. Of these, 31 (53%) were monomicrobial, and the rest were polymicrobial. The most common organisms isolated were Candida species, Staphylococcus aureus, and Pseudomonas aeruginosa. All infections were local (cellulitis, complicated skin, and skin structure infections including abdominal wall abscess) with no cases of concomitant bacteremia being documented. Most of the organisms isolated were susceptible to commonly used antimicrobial agents, although some quinolone-resistant and some multidrug-resistant organisms were isolated.ConclusionsThis retrospective study provides descriptive data regarding PEG tube insertion site infections. These data have helped us update institutional guidelines for infection prevention and treatment as part of our focus on antimicrobial stewardship.

Rare Case of Septic Arthritis Caused by Candida krusei: Case Report and Literature Review

To the Editor: Acute monoarthritis is a common rheumatological emergency that requires immediate investigation to rule out a possible infection. Candida species can be rarely isolated from joint infections1; however, as more aggressive strategies are used to treat patients with hematological malignancies, new pathogens have emerged2. We describe a 75-year-old white man with a diagnosis of acute myeloid leukemia (AML) who was admitted to the University of Texas M.D. Anderson Cancer Center with neutropenic fever and sudden onset of severe right knee pain without trauma. His history was significant for diabetes mellitus and relapsing AML refractory to treatment. At the time of admission he had been neutropenic for a year and was on his first course (day 47) of salvage therapy with fludarabine and cytarabine. He was receiving prophylaxis with fluconazole 200 mg/daily and valacyclovir 500 mg/daily for the past 4 months and levofloxacin 500 mg/daily for the past year. Antifungal prophylaxis was switched to voriconazole 200 mg twice daily, 1 month before admission, around the same time he developed right lower extremity cellulitis, treated with broad-spectrum antibiotics. On examination, he was febrile at 38.3°C and his right knee was swollen and tender with no erythema. Passive and … Address correspondence to Dr. H. Lu, Department of General Internal Medicine, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Unit 1465, Houston, Texas, USA. E-mail: hlu{at}mdanderson.org

Bacterial Colonization and Host Immunity

The gastrointestinal (GI) tract is a highly evolved anatomical and functional structure that encounters a vast array of antigens, food particles, and microorganisms on a daily basis. The intestine has to perform the daunting function of absorbing nutrients essential for human life, while keeping us protected from luminal antigens, particles, and pathogens. The adult human intestine is home to an enormous number of microorganisms that is extraordinarily complex, collectively known as intestinal microbiota. Understanding our relationship with commensal flora has gained more depth in recent years; new data demonstrate that gastrointestinal microbiota plays an important role in defense against pathogenic organisms. Since it is only a thin monolayer of epithelial cells that separates us from the intestinal flora and pathogens, the intestine has acquired specialized cells organized in complex structures that have to perform the function of defending us against pathogens by initiating innate and adaptive immune responses. By constant signaling and communication, intestinal immune cells are organized in a vast and complex network that contributes to the maintenance of homeostasis.