Alan I. Hartstein

Multiple intensive care unit outbreak of Acinetobacter calcoaceticus subspecies anitratus respiratory infection and colonization associated with contaminated, reusable ventilator circuits and resuscitation bags

PURPOSE Acinetobacter calcoaceticus subspecies anitratus (A. anitratus) can cause nosocomially and community acquired pneumonia. Source identification of the organism is often difficult. An outbreak of respiratory infection and colonization with A. anitratus affecting 93 ventilated patients in all six of a hospitals intensive care units (ICUs) over 10 months is described. PATIENTS AND METHODS In April 1984, the infection control staff started to review positive culture results from all patients in all ICUs. At this point, information on significant isolates was recorded by patient, site, date, genus and species, and antimicrobial susceptibility. During the month of August 1984, an increased number of A. anitratus isolates from sputum began to be detected. Information was expanded to include the date of hospital admission, ICU admission, intubation, and extubation; the dates and types of all surgical procedures; the results and dates of all prior sputum cultures; and the use of nebulized bronchodilator medications. Monthly numbers of cases were compared for four months prior to the outbreak, during the outbreak, and for seven months after the outbreak. Plasmid DNA from isolates was prepared, electrophoresed, and visualized. Isolates were designated according to the molecular weights of visualized plasmids. RESULTS Barrier precautions and improved staff handwashing did not diminish the frequency of new cases. When pasteurized, reusable ventilator circuits and resuscitation bags were cultured for the possibility of low-level contamination, 18 percent were positive for A. anitratus. Terminal ethylene oxide sterilization of these devices was associated with prompt control of the outbreak. Plasmid DNA analysis of isolates from patients involved in the outbreak, contaminated devices, and the hands of personnel responsible for device disinfection revealed two predominant plasmid profiles. After outbreak control, isolates with these profiles were found much less frequently in patient specimens. CONCLUSION Contaminated, reusable ventilator support equipment may be a leading cause for the extent of A. anitratus in the sputum of intubated patients. This problem is potentially correctable by the use of terminal etyhlene oxide sterilization of reusable ventilator circuits and resuscitation bags.

Chronic Osteomyelitis caused by Staphylococcus Aureus: Controlled Clinical Trial of Nafcillin Therapy and Nafcillin-Rifampin Therapy

A controlled trial of treatment of chronic osteomyelitis caused by Staphylococcus aureus compared nafcillin alone with nafcillin plus rifampin for a six-week period. Treatment was well tolerated, the only adverse effect being mild neutropenia in four of 18 patients; no toxicity was observed from rifampin. Eight of ten patients in the combined treatment group had a favorable clinical response (with follow-up of two to four years) as compared to four of eight in the nafcillin group (P=.2). Despite the failure to show a statistically significant advantage of rifampin plus nafcillin, we conclude that the combination, along with appropriate surgery, should be considered for patients with chronic staphylococcal osteomyelitis.

Nontuberculous Mycobacterial Peritonitis Associated With Continuous Ambulatory Peritoneal Dialysis

We report two patients undergoing continuous ambulatory peritoneal dialysis (CAPD) in whom peritonitis developed and nontuberculous mycobacteria were isolated from peritoneal fluid. In one, Mycobacterium avium-intracellularis was the only organism isolated. Despite a three-month course of antibiotics to which the organism showed in vitro sensitivity, there was no apparent response. The patient died, and an autopsy showed disseminated mycobacterial disease. In the second case, Mycobacterium fortuitum and diphtheroids were isolated from the peritoneal fluid. Although it was not clear that the mycobacterium was solely responsible for the peritonitis in the second case, the infection failed to resolve with antibiotic therapy appropriate for diphtheroids. This patient also died. Both patients had indolent, chronic infections, although there was granulocyte predominance in the peritoneal fluid. Both had involvement of the catheter exit site. To our knowledge, these are the first reported cases of nontuberculous mycobacterial peritonitis in CAPD patients. We recommend evaluation for mycobacteria, including cultures and stains of dialysate specimens, in all cases of CAPD-associated peritonitis where no organism is identified, or where no improvement is noted after 48 hours of therapy. Repeated cultures for mycobacteria are appropriate for suggestive cases. Since these infections are difficult to treat, it may be prudent to remove the dialysis catheter if they are isolated.

Plasmid DNA Fingerprinting of Acinetobacter calcoaceticus Subspecies anitratus From Intubated and Mechanically Ventilated Patients

Forty-three intubated and mechanically ventilated patients in five intensive care units (ICUs) of one hospital developed respiratory colonization or infection with Acinetobacter calcoaceticus subspecies anitratus over a 16-month interval. Neither the frequency nor rate of A anitratus isolation exceeded the hospital endemic norms. Single isolates from 34 of the patients were subtyped by plasmid DNA analysis, two biotyping systems and antimicrobial susceptibility to 24 drugs. Plasmid DNA fingerprints were distinct in 18 isolates (they differed from each other and all others), similar in two and identical or similar in ten. The latter group of isolates were recovered from patients in four ICUs. Reproducibility of biotyping was poor. Neither biotyping nor antimicrobial susceptibility were successful in identifying sameness among the group isolates nor differences among other isolates. We conclude that plasmid DNA fingerprinting should be used to assess the possibility of multiple patient transmissions of the same A anitratus strain in the absence of an obvious outbreak.

Effects of antacids and dialysate dwell times on multiple-dose pharmacokinetics of oral ciprofloxacin in patients on continuous ambulatory peritoneal dialysis.

Six stable patients on continuous ambulatory peritoneal dialysis were evaluated for the appearance of ciprofloxacin in their peritoneal dialysate following oral ingestion of 750 mg of the drug every 12 h for four doses. Three subjects participated in this study twice, once while taking and once while abstaining from phosphate-binding aluminum antacids. Subjects tolerated the medication without evidence of toxicity. Food may have delayed or decreased the absorption of ciprofloxacin, whereas antacids definitely decreased the absorption of the drug. Peak concentrations in serum noted in the absence of antacids ranged from 2.9 to 6.4 micrograms/ml, and peak concentrations in dialysate in the absence of antacids ranged from 1.8 to 4.5 micrograms/ml. Peak ciprofloxacin concentrations in serum achieved in subjects taking antacids were 14 to 50% of those achieved in subjects without antacids. The peak concentrations in dialysate achieved in subjects on antacids were 8 to 33% of those observed in subjects off antacids. The clearance of ciprofloxacin by continuous ambulatory peritoneal dialysis represented 2% of the total body (systemic) clearance. Simultaneous ratios of concentration in dialysate to concentration in serum (D/S) were determined at various durations of dialysate dwelling within the peritoneum. A progressive rise of the D/S ratio was noted as dwell time increased. At 4 h D/S was 0.57 +/- 0.07 (mean +/- standard error of the mean; n = 9), and at 8 h it was 0.75 +/- 0.04 (n = 26). Long-dwell exchanges may be necessary to achieve reasonable concentrations of orally ingested ciprofloxacin in dialysate.

Plasmid DNA analysis of Staphylococcus epidermidis isolated from blood and colonization cultures in very low birth weight neonates

We prospectively studied the course of colonization and sepsis with Staphylococcus epidermidis among 29 very low birth weight neonates undergoing prolonged umbilical catheterization. S. epidermidis bacteremia occurred in 7 patients. In 6 bacteremia was preceded by positive colonization cultures. Isolates obtained from nares, base of umbilicus, umbilical catheter entry sites, catheter tips and blood were examined for plasmid DNA profiles. In 4 patients the plasmid profiles of the catheter entry site isolates were identical with those of the blood isolates. In the other 3 bacteremic patients plasmid profiles of the catheter entry site and blood isolates were different. No correlation was observed in the plasmid DNA patterns of isolates obtained from catheter tip cultures as compared to the corresponding blood cultures. The blood isolates from bacteremic patients had different plasmid profiles.

Use of an estimation method to derive an appropriate denominator to calculate central venous catheter-associated bloodstream infection rates

An outbreak investigation was conducted to determine if an increase in bloodstream infections (BSIs) in patients with central venous catheters (CVC) had occurred. Because other methods of obtaining CVC days were not feasible, we used an estimation method based on a random 5% sample of medical records to determine the proportion of days that a CVC was present for each of three patient units. This calculated ratio was used to estimate the total CVC days for each unit. A cohort study was conducted in which the BSI rates before and during needleless device use were compared. This article describes the methods used to calculate this estimated denominator and discusses the need for such a denominator to be used by infection control practitioners when prospective collection of CVC days is not possible.

Anaerobic Bacterial Infection and Xanthogranulomatous Pyelonephritis: a Case Report

A young man presented with a history of uncorrected ureteropelvic junction obstruction 18 months in duration and clinical acute pyelonephritis. Retrograde pyelography showed unilateral pyonephrosis and cultures of purulent drainage proximal to the ureteropelvic junction revealed predominantly anaerobic bacteria and no aerobic gram-negative bacilli. Subsequent nephrectomy established a diagnosis of xanthogranulomatous pyelonephritis. Nephrectomy in combination with intensive antimicrobial therapy resulted in recovery. The contribution of anaerobic bacteria in the pathogenesis of xanthogranulomatous pyelonephritis is unknown. Anaerobic culture of urine and excised tissue in these patients may be indicated.

Plasmid DNA analysis, biotyping, and antimicrobic susceptibility as subtyping tests for Klebsiella pneumoniae and Klebsiella oxytoca

We compared plasmid DNA analysis, biotyping by Vitek, and disk diffusion antimicrobic susceptibility as subtyping tests of Klebsiella pneumoniae and Klebsiella oxytoca. The 92 tested isolates were from alternate, culture-positive patients over 6 months. No outbreak or cluster of infections was recognized during this interval. Plasmid DNA was detected in 85% of the isolates. Each isolate except one had a reproducible absence of plasmid DNA or a reproducible plasmid DNA profile on repetitive testing. Restriction endonuclease enzyme analysis of plasmid DNA was necessary to distinguish differences among some isolates that had only large plasmids. Isolates with only large plasmids represented 18% of the collection. Of the 78 isolates with plasmid DNA, all but two were considered different from one another by plasmid DNA analysis. Biotyping and antimicrobic susceptibility testing were not highly reproducible. In addition, biotyping did not demonstrate a sufficient variety of patterns among the isolates for subtyping purposes. We conclude that plasmid DNA analysis is very useful as a subtyping test for isolates of K. pneumoniae and K. oxytoca. Neither biotyping nor antimicrobial susceptibility as performed in our laboratory had sufficient discriminatory power and reproducibility for subtyping these organisms.

Molecular epidemiology of Candida albicans colonization and fungemia in very low birthweight infants

OBJECTIVE This study investigated the relationship between colonization and fungemia. DESIGN This was a prospective study involving surveillance cultures of the nares, base of umbilicus, point of entry of umbilical catheter and parenteral fluids. Blood cultures were done when sepsis was suspected. All Candida albicans isolates were typed using restriction enzyme analysis of DNA. SETTING Patients were from the neonatal intensive care unit of a tertiary care hospital. POPULATION STUDIED Twenty-nine very low birthweight infants. MAIN RESULTS Eleven babies were colonized with C albicans and five of these babies developed fungemia, including five of seven who were colonized at the point of entry of the umbilical catheter. Three different strains of C albicans caused fungemia. In four of the five patients, initial catheter entry site isolates were identical to the subsequent blood isolates. Occasionally, infants were colonized with more than one strain of C albicans. CONCLUSIONS Preceding colonization with C albicans and, in particular, colonization at the site of entry of umbilical vascular catheters are risk factors for subsequent development of C albicans fungemia. Fungemic and colonizing isolates are usually identical to one another by DNA typing.