Diagnosis of Clostridium difficile-related disease.
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Bacterial Proteins↗
Biomedical subjects
D N Gerding
Publications and source records attributed to D N Gerding.
Diagnosis of pneumonia.
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Bacterial Infections↗
Evaluation of ciprofloxacin's synergism with other agents by multiple in vitro methods.
The efficacies of ciprofloxacin, ceftizoxime, azlocillin, mezlocillin, and amikacin (minimal inhibitory concentration and minimal bactericidal concentration) against six Pseudomonas aeruginosa, six Enterobacteriaceae, and six group D streptococcal strains were evaluated using both agar and broth susceptibility methods, two inoculum sizes (5.7 log10 colony-forming units (cfu)/ml and 7.7 log10 cfu/ml), and aerobic and anaerobic incubation conditions. The results showed agreement between broth and agar methods of susceptibility determination; inoculum effects with beta-lactam antimicrobials; and decreased susceptibility to amikacin under anaerobiasis. Ciprofloxacin combined with azlocillin, ceftizoxime, or aminoglycosides in broth microdilution checkerboards against 100 gram-negative bacilli and gram-positive cocci demonstrated that ciprofloxacin combined with azlocillin or ceftizoxime was synergistic against at least 50 percent of P. aeruginosa and Serratia marcescens isolates and that ciprofloxacin combined with amikacin was synergistic against at least 50 percent of S. marcescens and Staphylococcus aureus isolates. Ciprofloxacin and azlocillin in combination were evaluated by microdilution checkerboard, agar dilution, and broth macrodilution time-kill methods at two inoculum sizes to assess antibacterial activity. Comparison between in vitro combination methods showed the following: the presence or absence of checkerboard synergism (as defined by the fractional inhibitory concentration index and the fractional bactericidal concentration index) with ciprofloxacin and azlocillin did not correlate with time-kill results; and good agreement between methods when comparing broth macrodilution time-kill (3 log10 cfu/ml or more decrease) with antimicrobial combinations at a single concentration in both agar and microdilution broth for ciprofloxacin and azlocillin. Rabbit studies using subcutaneous dialysis membrane chambers inoculated with six P. aeruginosa, six Enterobacteriaceae, and six group D streptococcal strains were performed using ciprofloxacin, azlocillin, ceftizoxime, and amikacin alone and in combination as therapy. In vitro testing of antibiotic combinations that provided the best prediction of in vivo outcome were combination antibacterial activity (3 log10 cfu/ml or more decrease) at 24 hours using either broth macrodilution time-kill or antimicrobial combinations at a single concentration in either agar or broth (microdilution). For the most efficacious in vivo combination, ciprofloxacin plus azlocillin, there was in vitro correlation with in vivo outcome for 17 of 18 isolates.
Animals↗
Treatment of ciprofloxacin- and ceftizoxime-induced resistant gram-negative bacilli.
Gram-negative bacilli that had been selected for resistance to either ciprofloxacin or ceftizoxime as a result of previous exposure to these agents were inoculated into semipermeable subcutaneous chambers in rabbits, modeling a locally neutropenic closed-space infection. Five resistant organisms, one Serratia marcescens (157) and four Pseudomonas aeruginosa (864, 876, 913, and 915) strains, were selected by previous therapy with ciprofloxacin, and six Pseudomonas strains (833, 845, 864, 876, 913, and 915) were selected by previous therapy with ceftizoxime. Animals were treated with either single antibiotics or combinations of antibiotics for four days, and the response was determined by quantitative bacterial count measurements. The selected (induced) resistance was stable for at least four days, both in vivo and in vitro, but was limited to the antibiotic class of the agent used for induction. Four of five isolates for which resistance had been induced by ciprofloxacin returned to preinduction susceptibility by the eight day of subculture. Organisms that were selected for resistance to ciprofloxacin were successfully treated by a combination of azlocillin and amikacin, and were as sensitive to that regimen as were the parent, uninduced strains. Organisms selected for resistance by pretreatment with ceftizoxime were successfully treated by the combination of ciprofloxacin plus azlocillin, and this regimen was also equally active against the selected strains as it was against the parental isolates. Although selection or induction of resistance is a potential problem with all new potent antimicrobial agents, it appears that infections due to these isolates can still be treated successfully through the use of appropriate combination chemotherapy.
Amikacin↗
Osteomyelitis in the feet of diabetic patients. Long-term results, prognostic factors, and the role of antimicrobial and surgical therapy.
Fifty-one diabetic patients with osteomyelitis of the foot were studied to determine potential prognostic factors and the role of antimicrobial therapy. Most of the patients were elderly, with diminished pulses, a sensory neuropathy, and a polymicrobial infection. Twenty-seven patients had a good outcome, defined as clinical resolution at the time of the last follow-up examination, without the need for amputation. The mean duration of follow-up for these patients was 19 months. Fifteen patients had a below-knee amputation, and nine had a toe amputation. The absence of necrosis and/or gangrene, the presence of swelling, and the use of antimicrobial therapy active against the isolated pathogens for at least four weeks intravenously, or combined intravenously and orally for 10 weeks, predicted a good outcome. Diabetic foot osteomyelitis, in the absence of extensive necrosis or gangrene, usually responds to antimicrobial therapy without the need for an ablative surgical procedure.
Amputation, Surgical↗
Pseudomonas infection of the biliary system resulting from use of a contaminated endoscope.
Pseudomonas aeruginosa was present in bile cultures from 10 patients who had undergone previous endoscopic retrograde cholangiopancreatography in 1984. After environmental cultures and review of instrument disinfection, we traced the infections to a single endoscope contaminated with P. aeruginosa, serotype 10. Although the instrument had been cleaned repeatedly with an automatic endoscope cleaning machine, P. aeruginosa survived on residual moisture left in the channels of the endoscope. Contamination ended only after we began to manually suction alcohol through the endoscope before air drying. In 5 of 10 patients, P. aeruginosa caused clinical infections including gangrenous cholecystitis, abscesses, and death. We could identify no factor that distinguished symptomatic from asymptomatic patients. In asymptomatic patients, P. aeruginosa was recovered from gallbladder bile up to 2 mo after endoscopic retrograde cholangiopancreatography. As this P. aeruginosa epidemic was discovered retrospectively because we monitor bile cultures, we advocate this practice as part of endoscopic retrograde cholangiopancreatography procedures.
Bile↗
In vivo and in vitro activity of ciprofloxacin plus azlocillin against 12 streptococcal isolates in a neutropenic site model.
Closed-space neutropenic infection sites were simulated in rabbits by subcutaneous semipermeable chambers that were inoculated with 5 X 10(4) CFU/ml of various strains of Streptococcus pneumoniae, Streptococcus faecalis, and Streptococcus avium. Four hours after inoculation, treatment was begun with ciprofloxacin, 10 or 30 mg/kg, azlocillin, 100 mg/kg, amikacin, 15 mg/kg, procaine penicillin G, 300 U/dose, or gentamicin, 2 mg/kg, alone and in two-drug combinations. Antimicrobials were given intramuscularly every 6 hr for 16 doses. Extravascular chambers were sampled throughout the treatment course for bacterial counts and antimicrobial concentration. In vivo results were compared to in vitro tests of inhibition, killing, and synergism. Ciprofloxacin alone had little effect on the animal infection sites. Azlocillin alone reduced, in vivo, eight of 12 isolates greater than or equal to 5 log10 CFU/ml by 92 hr as compared to control. Azlocillin plus ciprofloxacin reduced all 12 isolates greater than or equal to 5 log10 CFU/ml by 92 hr, whereas amikacin plus azlocillin reduced only three and penicillin plus gentamicin only one of the six group D streptococcal isolates greater than or equal to 5 log10 CFU/ml.
Amikacin↗
In vitro activity of efrotomycin, ciprofloxacin, and six other antimicrobials against Clostridium difficile.
The susceptibility of 69 clinical isolates of Clostridium difficile from the Minneapolis Veterans Administration Medical Center and 29 C. difficile strains from other hospitals to efrotomycin, ciprofloxacin, and six other antimicrobials was tested in vitro by agar dilution. Ciprofloxin (MIC50 and MIC90 = 8 mcg/ml) was only moderately active whereas efrotomycin (MIC50 = 0.125, MIC90 = 0.25 mcg/ml) was highly active against C. difficile.
Anti-Bacterial Agents↗
Ceftazidime and amikacin alone and in combination against Pseudomonas aeruginosa and Enterobacteriaceae.
The efficacy of ceftazidime alone and combined with amikacin was studied in a rabbit model simulating closed-space infections at locally neutropenic sites. Six strains of Pseudomonas aeruginosa, and six Enterobacteriaceae (two strains each of Klebsiella pneumoniae and Serratia marcescens and one strain each of Escherichia coli and Citrobacter freundii) in pooled rabbit serum were each inoculated into separate subcutaneous semipermeable chambers. Intramuscular antibiotic therapy was begun 4 hr later with ceftazidime (50 mg/kg) alone and combined with amikacin (15 mg/kg) for Enterobacteriaceae or ceftazidime (100 mg/kg) alone and combined with amikacin (15 mg/kg) for pseudomonads every 6 hr for 16 doses. Amikacin alone was ineffective for all 12 strains. Ceftazidime alone was successful (greater than or equal to 5.5 log10 colony forming units (CFU)/ml decrease from drug-free control) in eliminating five of six Enterobacteriaceae but was not successful against any of the pseudomonads. Ceftazidime plus amikacin was successful against the same five of six Enterobacteriaceae and five of six pseudomonads. The best in vitro tests for the prediction of in vivo outcome were high inoculum (greater than or equal to 7 log10 CFU/ml) susceptibility, checkerboard synergism testing, and conventional inoculum time-kill rates at concentrations of antimicrobials simulating extravascular levels obtained in vivo.
Amikacin↗
Occurrence and reproducibility of the "skip" phenomenon in bactericidal testing of Staphylococcus aureus.
A "skip" phenomenon, in which subcultures to determine bactericidal endpoints show discordant results, can make bactericidal testing of Staphylococcus aureus difficult to interpret. Either a single or several consecutive concentrations may be skipped, with insignificant growth from these concentrations, but heavy growth from higher antimicrobic concentrations. Replicate macrodilution minimum bactericidal concentration testing of cephalothin against S. aureus was investigated to determine the frequency and reproducibility of the skip phenomenon in this test. In preliminary testing, the skip phenomenon occurred at 24 hr in 11 of the 30 tests performed on ten S. aureus strains. Incubation of tubes for 48 hr before subculture markedly reduced the number of tests containing a skip tube (four of 30). The skip phenomenon was not reproducible either within concurrent replicate testing or on repeat testing of the same isolate on subsequent days. The ten strains were retested in replicative trials using the macrodilution test comparing Mueller-Hinton broth (MHB) and MHB supplemented with Tween 80. The number of skips occurring in the supplemented broth test was the same (two of 22) at 24 hr as nonsupplemented broth. For reproducible results, macrodilution minimum bactericidal testing requires performance of the test in duplicate, with repeat subculture at 48 hr if the skip phenomenon occurs in both trials at the 24-hr subculture. Killing curves performed on these isolates did not appear to demonstrate any relationship between the skip phenomenon and the paradoxical effect described by Eagle.
Cephalothin↗
Detection of C. difficile toxin A (enterotoxin)
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Bacterial Toxins↗
Cephalothin clearance of Staphylococcus aureus from two experimental infection sites in the presence and absence of local phagocytic cells.
The clearance of Staphylococcus aureus from perforated peritoneal capsules which are accessible to phagocytic cells, and subcutaneous Visking chambers which exclude phagocytes, was studied simultaneously in eight rabbits implanted with both devices. Animals were treated with cephalothin, 100 mg/kg im every 8 h for sixteen doses, beginning 24 h after inoculation of the infection sites with S. aureus (cephalothin MIC 0.125 mg/l, MBC 0.5 mg/l). At the start of cephalothin, subcutaneous chambers contained a higher concentration of S. aureus (8.4 log10 cfu/ml) than peritoneal capsules (6.8 log10 cfu/ml, P less than 0.001). There was a significant bactericidal effect in subcutaneous chambers on both the third and sixth day of treatment (P less than 0.002), whereas in peritoneal capsules this did not occur until day six. The total reduction in bacterial count in subcutaneous chambers (7.0 log10 cfu/ml) was significantly greater than in capsules (4.4 log10 cfu/ml, P less than 0.002). The mean concentration of cephalothin in subcutaneous chambers (10.7 mg/l) was significantly higher than in peritoneal capsules (6.1 mg/l, P less than 0.02), but no difference in in-vitro killing of S. aureus was detected at these concentrations. We conclude that cephalothin clearance of S. aureus from a site accessible to phagocytes was delayed when compared to a phagocyte-inaccessible site.
Animals↗
More than one DNA sequence encodes the 2''-O-adenylyltransferase phenotype.
Biochemical and phenotypic assays indicate that three enterobacterial R plasmids isolated in a single hospital encode 2''-O-adenylyltransferase [ANT(2'')], and an ANT(2'')-specific probe was developed from one plasmid. Southern hybridization revealed the three plasmids to be unrelated and, further, showed their ANT(2'')-encoding genes to be different.
Bacterial Proteins↗
Treatment and long-term follow-up of foot infections in patients with diabetes or ischemia: a randomized, prospective, double-blind comparison of cefoxitin and ceftizoxime.
The efficacy and safety of ceftizoxime and cefoxitin were compared in a randomized, double-blind study of therapy for lower extremity infections in patients with diabetes mellitus or peripheral vascular disease. Overall clinical responses were satisfactory in 82% (23/28) of patients treated with ceftizoxime and in 68% (17/25) of patients treated with cefoxitin. The difference was not statistically significant. Ceftizoxime had superior in vitro activity against Enterobacteriaceae, especially Enterobacter cloacae, whereas cefoxitin had better activity against the Bacteroides fragilis group. Relapses of infection were common in both groups during long-term follow-up; only about one third of patients in either group maintained satisfactory outcomes after one year. More than half of the patients in both groups responded to one or more courses of medical therapy and avoided major amputations for one year following entry into the study.
Aged↗
Neutrophil localization in acute and chronic experimental abscesses.
Abdominal abscesses are associated with a high mortality, and usually require surgical drainage for cure. A potential mechanism explaining the inability of the host to clear this infection may be in part a result of the inability of the neutrophil to localize at the site of an established infection. To study this question, either acute (4 hours old) or chronic (2 weeks old) abscesses caused by Staphylococcus aureus were created in perforated capsules implanted in the peritoneal cavity of rabbits. Homologous neutrophils were obtained from donor rabbits 4 hours after peritoneal glycogen stimulation and labeled with indium 111 oxine. Only 0.71% of injected 111In-labeled neutrophils localized in the chronic abscesses, compared with 1.77% in acute abscesses (P less than or equal to 0.01). Animals with chronic infections had a lower intravascular recovery of injected neutrophils (P less than 0.002). Failure of neutrophil localization was not associated with less chemotactic activity within the abscess, as measured by a chemotaxis-under-agarose assay, or caused by a barrier surrounding the abscess as detected by radionuclide imaging. Only 0.07% of injected neutrophils localized into acute abdominal abscesses in animals with a concomitant chronic subcutaneous abscess. These chronically infected animals also demonstrated a low peak intravascular recovery of injected neutrophils when compared with animals with only an acute infection (P less than 0.002). These data reveal that neutrophils localize to abscesses poorly in animals with chronic infections. The mechanism is possibly related to a systemic factor(s) associated with a lower intravascular recovery of injected neutrophils in chronically infected animals.
Abscess↗
Resistance surveillance programs and the incidence of gram-negative bacillary resistance to amikacin from 1967 to 1985.
Data relating to amikacin resistance among gram-negative bacilli were obtained by means of a review of published literature and resistance surveillance studies. Data from the first several years of amikacin use are difficult to interpret because the 10-micrograms disk used for Kirby-Bauer susceptibility testing resulted in apparent greater resistance than the present 30-micrograms disk. A large United States susceptibility surveillance program that monitors antibiotic use has shown a trend since 1977 of greater susceptibility of Serratia species and greater resistance among Pseudomonas aeruginosa for all the aminoglycosides. Pseudomonas resistance to amikacin has shown the smallest increase of any aminoglycoside. Several hospitals (Strong Memorial Hospital, University of Maryland Cancer Center, and Minneapolis Veterans Administration Medical Center) have reported either no significant change or a decrease in resistance to amikacin when it was the most frequently used aminoglycoside. In a large, 14-center, prospective study, high-level use of amikacin resulted in a significant decrease in resistance to gentamicin and tobramycin (p less than 0.01) and a marginal increase (p less than 0.05) in amikacin resistance. Significantly increased amikacin resistance has been reported from two institutions, neither of which used amikacin as the predominant aminoglycoside. Overall, the high-level use of amikacin in large multi-center surveillance programs for as long as five years has not resulted in a significant increase in amikacin resistance rates at any of the individual institutions surveyed.
Amikacin↗
In-111 Pseudomonas aeruginosa: a simple method of labeling live bacteria with a gamma-emitting radioisotope.
We describe a simple and reliable technique for labeling Pseudomonas aeruginosa with a readily available commercial preparation of indium-111 (111In) oxine. Labeling of a heavy bacterial suspension with 500 mu Ci of commercially prepared 111In-oxine resulted in a yield of 0.0004 mu Ci of cell-associated 111In per 10(6) colony-forming units (CFU). The label was 88% bacterially associated and did not effect viability of the organism. Radiolabeling a gram-negative organism with 111In-oxine provides a non-toxic, stable gamma-emitting bacterial tracer.
Animals↗