[show abstract][hide abstract] ABSTRACT: An understanding of the impact of antibiotics on the intestinal reservoir of KPC carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) is important to prevent its emergence. We used a mouse model to examine the effect of antibiotic treatment on the establishment and elimination of intestinal colonization with KPC-Kp. Mice (10 per group) received subcutaneous antibiotics daily for 8 days. On day 3 of treatment, 10(3) CFU of KPC-Kp was given orogastrically, and concentrations of KPC-Kp in stool were monitored. Additional experiments assessed the effects of antibiotic treatment on concentrations of total anaerobes and Bacteroides spp. in stool and the efficacy of orogastric gentamicin and polymyxin E in suppressing KPC-Kp colonization. Of four antibiotics with minimal activity against the KPC-Kp test strain (MIC ≥ 16 μg/ml), those that suppressed total anaerobes and bacteroides (i.e., clindamycin and piperacillin-tazobactam) promoted colonization by KPC-Kp (P < 0.001), whereas agents that did not suppress total anaerobes or bacteroides (i.e., ciprofloxacin and cefepime) did not (P = 0.35). Of two agents with moderate activity against the KPC-Kp test strain, ertapenem (MIC, 4 μg/ml) did not promote colonization by KPC-Kp, whereas tigecycline (MIC, 3 μg/ml) did (P < 0.001), despite not reducing levels of total anaerobes or bacteroides. Orogastric treatment with gentamicin and polymyxin E suppressed KPC-Kp to undetectable levels in the majority of mice. These data suggest that antibiotics that disturb the intestinal anaerobic microflora and lack significant activity against KPC-Kp promote colonization by this organism. The administration of nonabsorbed oral antibiotics may be an effective strategy to suppress colonization with KPC-Kp.
Antimicrobial Agents and Chemotherapy 03/2011; 55(6):2585-9. · 4.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: Tigecycline is a broad-spectrum glycylcycline antibiotic with potent in vitro activity against Clostridium difficile. We used a mouse model to test the hypothesis that tigecycline has a low propensity to promote colonization and toxin production by C. difficile due to inhibitory activity in the colon. Mice (5 to 8 per group) received subcutaneous injections of tigecycline (low and high doses) alone or in combination with clindamycin for 6 days. Growth of and toxin production by 3 strains of C. difficile (tigecycline MICs ≤ 0.012 μg/ml) were measured in cecal contents collected 6 h or 3 days after the final antibiotic dose. Antibiotic concentrations were measured using a bioassay, and concentrations of total anaerobes and Bacteroides spp. were measured. The effects of tigecycline on rendering mice susceptible to colonization with and reducing the burden of C. difficile were also examined. In comparison to saline controls, clindamycin promoted the growth of C. difficile (P < 0.001) in cecal contents, whereas tigecycline did not. Tigecycline did not suppress total anaerobes or Bacteroides spp. in comparison to saline controls. Concurrent administration of tigecycline prevented clindamycin-induced promotion of C. difficile in cecal contents collected 6 h or 3 days (high dose only) after the final antibiotic dose. Tigecycline did not promote the establishment of colonization in mice, yet it did not reduce concentrations of C. difficile in animals with established colonization. In summary, tigecycline did not promote the growth of or toxin production by C. difficile, probably due to inhibitory activity against C. difficile and relative sparing of indigenous anaerobic microflora.
Antimicrobial Agents and Chemotherapy 02/2011; 55(2):546-9. · 4.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine whether a multihospital Clostridium difficile outbreak was associated with epidemic strains and whether use of particular fluoroquinolones was associated with increased infection rates, we cultured feces from C. difficile-infected patients. Use of fluoroquionolones with enhanced antianaerobic activity was not associated with increased infection rates.
[show abstract][hide abstract] ABSTRACT: Environmental surfaces play an important role in transmission of healthcare-associated pathogens. There is a need for new disinfection methods that are effective against Clostridium difficile spores, but also safe, rapid, and automated.
The Tru-D Rapid Room Disinfection device is a mobile, fully-automated room decontamination technology that utilizes ultraviolet-C irradiation to kill pathogens. We examined the efficacy of environmental disinfection using the Tru-D device in the laboratory and in rooms of hospitalized patients. Cultures for C. difficile, methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE) were collected from commonly touched surfaces before and after use of Tru-D.
On inoculated surfaces, application of Tru-D at a reflected dose of 22,000 microWs/cm(2) for approximately 45 minutes consistently reduced recovery of C. difficile spores and MRSA by >2-3 log10 colony forming units (CFU)/cm2 and of VRE by >3-4 log10 CFU/cm(2). Similar killing of MRSA and VRE was achieved in approximately 20 minutes at a reflected dose of 12,000 microWs/cm(2), but killing of C. difficile spores was reduced. Disinfection of hospital rooms with Tru-D reduced the frequency of positive MRSA and VRE cultures by 93% and of C. difficile cultures by 80%. After routine hospital cleaning of the rooms of MRSA carriers, 18% of sites under the edges of bedside tables (i.e., a frequently touched site not easily amenable to manual application of disinfectant) were contaminated with MRSA, versus 0% after Tru-D (P < 0.001). The system required <5 minutes to set up and did not require continuous monitoring.
The Tru-D Rapid Room Disinfection device is a novel, automated, and efficient environmental disinfection technology that significantly reduces C. difficile, VRE and MRSA contamination on commonly touched hospital surfaces.
[show abstract][hide abstract] ABSTRACT: Proton pump inhibitors (PPIs) have been associated with Clostridium difficile infection (CDI) in several recent studies. However, other studies have not shown this association, and the mechanism by which PPIs might promote CDI has not been elucidated. We hypothesized two possible mechanisms of causation: first, by raising pH, PPIs may prevent gastric contents from killing C. difficile spores; second, gastric contents of PPI-treated patients may promote germination and outgrowth of C. difficile spores. Survival rates of spores from six different strains of C. difficile in acidic gastric contents were assessed using quantitative cultures on selective media. Germination and outgrowth of spores were assessed by heat shock at 80 degrees C, phase-contrast microscopy, and ethanol shock after incubation for 24 h in the gastric contents of patients and in the gastric, small intestinal, and cecal contents of mice. C. difficile spores survived and remained dormant in nonbilious gastric contents with acidic pH. Germination did not occur in unmodified gastric contents of patients but did occur with the addition of taurocholic acid and amino acids. In mice, germination did not occur in gastric contents but did occur in small intestinal and cecal contents. In summary, C. difficile spores survived in acidic gastric contents and did not undergo germination and outgrowth in gastric contents, probably due to lack of essential germinants, such as taurocholic acid. Our results suggest that the effects of PPIs in the stomach do not contribute to the pathogenesis of CDI.
Antimicrobial Agents and Chemotherapy 09/2009; 53(10):4133-7. · 4.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: Healthy infants frequently acquire Staphylococcus aureus colonization; however, the modes of transmission are not well defined. In this study, 8 of 23 (35%) infants cultured at age 2 weeks acquired S aureus carriage, but only 1 infant had a family member with nasal carriage of the same clone, suggesting that sources other than colonized family members may account for a significant proportion of cases.
American journal of infection control 04/2009; 37(7):598-600. · 3.01 Impact Factor
[show abstract][hide abstract] ABSTRACT: In a culture survey, we found that 42% of hospital privacy curtains were contaminated with vancomycin-resistant enterococci, 22% with ethicillin-resistant Staphylococcus aureus, and 4% with Clostridium difficile. Hand imprint cultures demonstrated that these pathogens were easily acquired on hands. Hospital curtains are a potential source for dissemination of healthcare-associated pathogens.
Infection Control and Hospital Epidemiology 10/2008; 29(11):1074-6. · 4.02 Impact Factor
[show abstract][hide abstract] ABSTRACT: For treatment of mild to moderate Clostridium difficile-associated disease (CDAD), oral metronidazole has been recommended as the preferred agent, in part due to concern that vancomycin may be more likely to promote colonization by vancomycin-resistant enterococci (VRE). We performed a prospective observational study to examine the effects of oral metronidazole or vancomycin treatment of CDAD on acquisition and concentration of VRE stool colonization. Before, during, and after 90 courses of CDAD therapy, stool samples were cultured for VRE, and the concentrations were quantified. Eighty-seven subjects (97%) had received antibiotics within the past month. For 56 treatment courses in which preexisting VRE colonization was present, metronidazole (n = 37 courses) and vancomycin (n = 19 courses), each promoted persistent VRE overgrowth during therapy, and the concentration decreased significantly in both groups by approximately 2 weeks after completion of treatment (P <0.049). For 34 treatment courses in which baseline cultures were negative for VRE, new detection of VRE stool colonization occurred during 3 (14%) of the 22 courses of metronidazole and 1 (8%) of the 12 courses of vancomycin (P = 1.0). These results demonstrate that both oral metronidazole and oral vancomycin promote the overgrowth of VRE during treatment of CDAD. New CDAD treatments are needed that are less likely to disrupt the intestinal microflora and promote overgrowth of healthcare-associated pathogens.
Antimicrobial Agents and Chemotherapy 08/2008; 52(7):2403-6. · 4.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: After mice received orogastric administration of a fluoroquinolone-resistant Klebsiella pneumoniae strain, subcutaneous treatment with ciprofloxacin, levofloxacin, and moxifloxacin promoted persistent low-density colonization in 10% to 40% of the mice, whereas treatment with clindamycin consistently promoted high-density colonization. No emergence of fluoroquinolone-resistant gram-negative bacilli was detected in the mice during or after treatment with the fluoroquinolone antimicrobial agents.
Antimicrobial Agents and Chemotherapy 08/2008; 52(9):3457-60. · 4.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: Proton pump inhibitors (PPIs) have been identified as a risk factor for Clostridium difficile-associated diarrhea (CDAD), though the mechanism is unclear because gastric acid does not kill C. difficile spores. We hypothesized that the vegetative form of C. difficile, which is killed by acid, could contribute to disease pathogenesis if it survives in room air and in gastric contents with elevated pH. We compared the numbers of C. difficile spores and vegetative cells in stools of patients prior to and during the treatment of CDAD. We assessed the survival of vegetative cells on moist or dry surfaces in room air versus anaerobic conditions and in human gastric contents, in pH-adjusted gastric contents, and in gastric contents from individuals receiving PPI therapy. Stool samples obtained from patients prior to the initiation of antibiotic treatment for C. difficile contained approximately 10-fold more vegetative cells than spores. On dry surfaces, vegetative C. difficile cells died rapidly, whereas they remained viable for up to 6 h on moist surfaces in room air. Vegetative C. difficile cells had only marginal survival in gastric contents at low pH; adjustment to a pH of >5 resulted in survival similar to that in the phosphate-buffered saline control. The survival of vegetative C. difficile in gastric contents obtained from patients receiving PPIs was also increased at a pH of >5. The ability of the vegetative form of C. difficile to survive on moist surfaces and in gastric contents with an elevated pH suggests a potential mechanism by which PPI therapy could increase the risk of acquiring C. difficile.
Antimicrobial Agents and Chemotherapy 08/2007; 51(8):2883-7. · 4.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: Exposure to pH 1 or 2 buffers or acidic gastric contents resulted in the killing of vancomycin-resistant Enterococcus sp., Klebsiella pneumoniae, Staphylococcus aureus, and Candida glabrata but not Clostridium difficile spores. Nitrite enhanced killing under acidic conditions, but significant killing of C. difficile spores required nitrite concentrations above usual physiological levels.
Antimicrobial Agents and Chemotherapy 12/2006; 50(11):3901-4. · 4.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: Proton pump inhibitor treatment of clindamycin-treated mice elevated the gastric pH and facilitated the establishment of colonization of the large intestine by vancomycin-resistant Enterococcus spp. (75 to 80%, versus 20 to 25% for saline-treated controls) and Klebsiella pneumoniae (90%, versus 30% for saline-treated controls). These findings demonstrate a mechanism by which proton pump inhibitor therapy could contribute to the dissemination of nosocomial pathogens.
Antimicrobial Agents and Chemotherapy 12/2006; 50(11):3905-7. · 4.57 Impact Factor