Pseudomonas aeruginosa: growth in distilled water from hospitals.

Pseudomonas aeruginosa can grow relatively fast in distilled water obtained in hospitals and achieve high cell contaminations which remain stable for long periods of time. Cells grown in distilled water react quite differently to chemical and physical stresses than cells grown in standard laboratory culture media.

Isoenzyme analysis of Pseudomonas cepacia as an epidemiologic tool.

Multilocus enzyme electrophoresis has successfully been used to establish basic marker systems for the epidemiologic analysis of a variety of bacterial pathogens. This study was done to determine the efficacy of this technique for characterizing Pseudomonas cepacia, using 31 known-related strains isolated during an outbreak of infections involving intrinsically contaminated povidone-iodine solution, and five outbreak-unrelated strains used in serotyping of P. cepacia. Crude cell extracts were analyzed by starch gel electrophoresis for electrophoretic variants using 13 enzyme substrates; esterase bands were detected using an additional four substrates. The 31 outbreak strains had identical isoenzyme patterns for all enzymes examined. Five electrophoretic types were obtained for the serotyping strains; electrophoretic mobilities of one of the five strains corresponded to the patterns obtained for the outbreak strains. These results suggest that enzyme electrophoretic typing may be a useful adjunct to other typing methods used in epidemiologic analyses of P. cepacia infections.

Outbreak of pyrogenic reactions at a dialysis center. Association with infusion of heparinized saline solution.

Twenty-three pyrogenic reactions occurred in 16 patients undergoing hemodialysis at a private dialysis center in the south central United States between November 23 and December 2, 1978. No deaths were attributed to reactions; however, 10 patients were hospitalized for observation after experiencing a reaction. Cultures of all blood specimens obtained from the patients gave negative results. Chills (75 percent), nausea and/or vomiting (30 percent), and fever (90 percent) were the most common signs and symptoms, with mean times of onset after starting dialysis of 1.1, 1.6, and 3.6 hours, respectively. An epidemiologic and laboratory investigation documented that reactions occurred only in patients who had anticoagulation with a dilute solution of heparin. Analyses of heparinized saline solution used during the outbreak revealed a bacterial count of 7.4 X 10(5)/ml and a bacterial endotoxin level of 1,300 ng/ml. Acinetobacter calcoaceticus var. Iwoffi was isolated from the solution. Diluted heparin solution was prepared at the dialysis center by adding commercially supplied sodium heparin to 0.9 percent sodium chloride infusion fluid. Bacteria and endotoxin were not detected in vials of stock heparin and bags of unopened 0.9 percent sodium chloride infusion fluid. We concluded that contamination of the solution occurred at the dialysis center. After changes in the preparation and use of heparin were instituted on December 4, 1978, no pyrogenic reactions occurred in more than 400 subsequent dialyses.

Colonization of the respiratory tract with Pseudomonas cepacia in cystic fibrosis. Risk factors and outcomes.

Between 1981 and 1983, some 85 patients with cystic fibrosis at Rainbow Babies and Childrens Hospital, Cleveland, developed colonization or infection of the respiratory tract with Pseudomonas cepacia. Twenty-nine (34 percent) of the colonized patients died; four were female patients with fulminant bacteremia with P cepacia prior to death. Case-control studies showed that increasing severity of underlying cystic fibrosis, increasing age, having a sibling with cystic fibrosis who was colonized with P cepacia, and previous hospitalizations were associated with increased risk of colonization. In patients with mild cystic fibrosis, no differences in clinical outcome were seen during the period of study; however, patients colonized with P cepacia who had moderate or advanced cystic fibrosis were hospitalized longer and died sooner after colonization, compared with control subjects with similar severity of cystic fibrosis. The excess mortality associated with such colonization varied in magnitude and trend according to the patient's sex and severity of underlying cystic fibrosis, reflecting the combined influence of colonization with P cepacia, sex, and severity of cystic fibrosis on the mortality of the patients. The source and mode of transmission of P cepacia were not determined, but the data suggest a possible nosocomial source. The results of this investigation showed that colonization with P cepacia most often affected patients with moderate or advanced cystic fibrosis and was associated with an adverse clinical outcome in these patients.

Determining the significance of coagulase-negative staphylococci isolated from blood cultures at a community hospital: a role for species and strain identification.

OBJECTIVES: To determine the degree to which species identification or strain relatedness assessment of successive blood culture isolates of coagulase-negative staphylococci (CNS) may improve the clinical diagnosis of bloodstream infection (BSI). SETTING: 400-bed community hospital. DESIGN: Prospective laboratory survey during which all CNS blood culture isolates obtained between mid-August 1996 and mid-February 1997 (study period) were saved and later identified to the species level; selected isolates were genotyped using pulsed-field gel electrophoresis at the Centers for Disease Control and Prevention (CDC). Retrospective review of medical records of 37 patients with multiple cultures positive for CNS. RESULTS: During the study period, 171 patients had blood cultures positive for CNS; 130 had single positive cultures and 41 had > or =2 positive cultures. Of these 41, 23 (62%) were from patients with signs and symptoms of BSI according to CDC surveillance definitions. Species identification and strain clonality of CNS isolates from patients with > or =2 positives revealed 3 (13%) of the 23 patients did not have a consistent CNS species, and another 3 (13%) did not have a consistent genotype in the > or =2 positive cultures, suggesting that CNS from these patients probably were contaminants. Thus, species identification and strain clonality assessment reduced by 27% the number of patients with BSI diagnosed based on the presence of symptoms and > or =2 positive blood cultures. CONCLUSIONS: Routine species identification and selected strain genotyping of CNS may reduce the misinterpretation of probable contaminants among patients with > or =2 positive blood cultures.

An outbreak of gram-negative bacteremia in hemodialysis patients traced to hemodialysis machine waste drain ports.

OBJECTIVE: To investigate an outbreak of gram-negative bacteremias at a hemodialysis center (December 1, 1996-January 31, 1997). DESIGN: Retrospective cohort study. Reviewed infection control practices and maintenance and disinfection procedures for the water system and dialysis machines. Performed cultures of the water and dialysis machines, including the waste-handling option (WHO), a drain port designed to dispose of saline used to flush the dialyzer before patient use. Compared isolates by pulsed-field gel electrophoresis. SETTING: A hemodialysis center in Maryland. RESULTS: 94 patients received dialysis on 27 machines; 10 (11%) of the patients had gram-negative bacteremias. Pathogens causing these infections were Enterobacter cloacae (n = 6), Pseudomonas aeruginosa (n = 4), and Escherichia coli (n = 2); two patients had polymicrobial bacteremia. Factors associated with development of gram-negative bacteremias were receiving dialysis via a central venous catheter (CVC) rather than via an arterio-venous shunt (all 10 infected patients had CVCs compared to 31 of 84 uninfected patients, relative risk [RR] undefined; P<.001) or dialysis on any of three particular dialysis machines (7 of 10 infected patients were exposed to the three machines compared to 20 of 84 uninfected patients, RR = 5.8; P = .005). E cloacae, P aeruginosa, or both organisms were grown from cultures obtained from several dialysis machines. WHO valves, which prevent backflow from the drain to dialysis bloodlines, were faulty in 8 (31%) of 26 machines, including 2 of 3 machines epidemiologically linked to case-patients. Pulsed-field gel electrophoresis patterns of available dialysis machine and patient E cloacae isolates were identical. CONCLUSIONS: Our study suggests that WHO ports with incompetent valves and resultant backflow were a source of cross-contamination of dialysis bloodlines and patients' CVCs. Replacement of faulty WHO valves and enhanced disinfection of dialysis machines terminated the outbreak.

Colonization of skilled-care facility residents with antimicrobial-resistant pathogens.

OBJECTIVES: To determine the frequency of and risk factors for colonization of skilled-care unit residents by several antimicrobial-resistant bacterial species, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus (VRE), or extended-spectrum-beta-lactamase-producing (ESBL-producing) (ceftazidime resistant) Klebsiella pneumoniae or Escherichia coli. DESIGN: Point-prevalence survey and medical record review. SETTING: The skilled-care units in one healthcare facility. PARTICIPANTS: 120 skilled-care unit residents. MEASUREMENTS: Colonization by each of the four antimicrobial-resistant pathogens during a point-prevalence survey, using rectal, nasal, gastrostomy-tube site, wound, and axillary cultures, June 1-3, 1998; 117 (98%) had at least one swab collected and 114 (95%) had a rectal swab collected. Demographic and clinical characteristics were evaluated as risk factors for colonization. All isolates were strain typed by pulsed-field gel electrophoresis of total genomic deoxyribonucleic acid. RESULTS: Of 117 participants, 50 (43%) were culture positive for > or =1 antimicrobial-resistant pathogen: MRSA (24%), ESBL-producing K. pneumoniae (18%) or E. coli (15%), and VRE (3.5%). Of 50 residents culture positive for any of these four antimicrobial-resistant species, 13 (26%) were colonized by more than one resistant species; only three (6%) were on contact-isolation precautions at the time of the prevalence survey. Risk factors for colonization varied by pathogen: total dependence on healthcare workers (HCWs) for activities of daily living (ADLs) and antimicrobial receipt for MRSA, total dependence on HCWs for ADLs for ESBL-producing K. pneumoniae, and antimicrobial receipt for VRE. No significant risk factors were identified for colonization by ESBL-producing E. coli. Among colonized patients, there was a limited number of strain types for MRSA (24 patients, 4 strain types) and ESBL-producing K. pneumoniae (21 patients, 3 strain types), and a high proportion of unique strain types for VRE (4 patients, 4 strain types) and FSBL-producing E. coli (17 patients, 10 strain types). CONCLUSION: A large unrecognized reservoir of skilled-care-unit residents was colonized by antimicrobial-resistant pathogens, and co-colonization by more than one target species was common. To prevent transmission of antimicrobial-resistant pathogens in long-term care facilities in which residents have high rates of colonization, infection-control strategies may need to be modified. Potential modifications include enhanced infection-control strategies, such as universal gloving for all or high-risk residents, or screening of high-risk residents, such as those with total dependence on HCWs for ADLs or recent antimicrobial receipt, and initiation of contact-isolation precautions for colonized residents.

A prolonged outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit: did staff fingernails play a role in disease transmission?

OBJECTIVES: To describe an outbreak of Pseudomonas aeruginosa bloodstream infection (BSI) and endotracheal tube (ETT) colonization in a neonatal intensive care unit (NICU), determine risk factors for infection, and make preventive recommendations. DESIGN: A 15-month cohort study followed by a case-control study with an environmental survey and molecular typing of available isolates using pulsed-field gel electrophoresis. SETTING AND PATIENTS: Neonates in the NICU of a university-affiliated children's hospital. INTERVENTIONS: Improved hand washing and restriction of use of long or artificial fingernails. RESULTS: Of 439 neonates admitted during the study period, 46 (10.5%) acquired P aeruginosa; 16 (35%) of those died. Fifteen (75%) of 20 patients for whom isolates were genotyped had genotype A, and 3 (15%) had genotype B. Of 104 healthcare workers (HCWs) from whom hand cultures were obtained, P aeruginosa was isolated from three nurses. Cultures from nurses A-1 and A-2 grew genotype A, and cultures from nurse B grew genotype B. Nurse A-1 had long natural fingernails, nurse B had long artificial fingernails, and nurse A-2 had short natural fingernails. On multivariate logistic regression analysis, exposure to nurse A-1 and exposure to nurse B were each independently associated with acquiring a BSI or ETT colonization with P aeruginosa, but other variables, including exposure to nurse A-2, were not. CONCLUSION: Epidemiological evidence demonstrated an association between acquiring P aeruginosa and exposure to two nurses. Genetic and environmental evidence supported that association and suggested, but did not prove, a possible role for long or artificial fingernails in the colonization of HCWs' hands with P aeruginosa. Requiring short natural fingernails in NICUs is a reasonable policy that might reduce the incidence of hospital-acquired infections.

Possible nosocomial transmission of Pseudomonas cepacia in patients with cystic fibrosis.

OBJECTIVE: To determine whether nosocomial transmission of Pseudomonas cepacia occurred at a hospital with endemic P cepacia infection of patients with cystic fibrosis. DESIGN: Two retrospective case-control studies. SETTING: A large pediatric cystic fibrosis center. PARTICIPANTS: To assess risk factors for acquisition of P cepacia, 18 cases, defined as any patient with cystic fibrosis with first documented isolation of P cepacia in 1988 or 1989, were compared with 18 matched P cepacia-negative controls with cystic fibrosis. To assess potential modes of nosocomial P cepacia transmission, 14 cases with a hospitalization(s) between their last P cepacia-negative culture and first P cepacia-positive culture were compared with 14 hospitalized P cepacia-negative controls with cystic fibrosis. METHODS: Handwiping cultures (N = 68) and selective environmental cultures were performed. MAIN RESULTS: Cases tended to be more likely than controls to have been hospitalized at the cystic fibrosis center in the 3 months before their first P cepacia-positive culture (P = .08). In addition, cases tended to be more likely than hospitalized controls with cystic fibrosis to have had a P cepacia-positive roommate (P = .06) before becoming colonized with P cepacia organisms. Pseudomonas cepacia was cultured from the hands of two individuals: a P cepacia-colonized patient who had just undergone chest physiotherapy and consequent coughing and the investigator who shook the P cepacia-positive patient's hand after the patient's procedure. CONCLUSIONS: These results suggest that in this cystic fibrosis center, hospitalization is a risk factor for P cepacia acquisition and that person-to-person transmission of P cepacia may occur in the hospital via hand contact.

Propionibacterium as a cause of postneurosurgical infection in patients with dural allografts: report of three cases.

OBJECTIVE AND IMPORTANCE: Although Propionibacterium acnes is a common inhabitant of human skin, it is an uncommon pathogen in postoperative infections. We report three cases of postoperative wound infection/osteomyelitis caused by P. acnes. CLINICAL PRESENTATION: Three patients underwent craniotomy for a supratentorial meningioma and had a dural allograft at the time of closure. The patients presented several weeks after surgery with clinical evidence of a wound infection. INTERVENTION: All patients were diagnosed with P. acnes infection and treated for this pathogen with appropriate antibiotics. The bone flap was removed in two patients. After antibiotic therapy, all patients demonstrated no further evidence of infection. CONCLUSION: To our knowledge, this is the first published report of P. acnes infection in patients with a dural substitute. The source of infection cannot be confidently ascertained; however, two patients had strains of P. acnes from one brand of graft, which were indistinguishable by pulsed field gel electrophoresis typing.

Use of packaged entrees as part of a weight-loss diet in overweight men: an 8-week randomized clinical trial.

AIM: This study assessed the efficacy of a weight-loss diet by using packaged portion-controlled entrees vs. a self-selected diet based on the United States Department of Agriculture Food Guide Pyramid (FGP). METHODS: Sixty healthy overweight men (body mass index (BMI) 26-42 kg/m2; aged 24-60 years) were randomized into two groups for an 8-week intervention. Group E consumed two portion-controlled entrees daily, plus recommended servings from the FGP. Group P consumed a self-selected diet consisting of a recommended number of servings from the FGP. Diets were designed to be isocaloric (1700 kcal) and identical in macronutrient composition (55% carbohydrate, 25% protein and 20% fat). Participants were instructed to make no changes in physical activity levels. Each group was blinded to the protocol of the other group, and received separate diet instructions, but no behavioural or diet counselling. Outcomes included weight, BMI, body composition by dual energy X-ray absorptiometry, waist and hip circumference, blood pressure (BP), fasting blood lipids, glucose, insulin and C-reactive protein. RESULTS: Fifty-one men completed the study. The portion-control group E (n = 25) experienced greater decreases in weight (-7.4 +/- 3.1 vs. -5.1 +/- 4.0 kg), BMI (-2.4 +/- 1.0 vs. -1.6 +/- 1.3 kg/m2), fat mass (-3.6 +/- 1.8 vs. -2.5 +/- 1.8 kg), waist circumference (-6.6 +/- 3.3 vs. -4.3 +/- 2.9 cm) and diastolic BP (-6.0 +/- 7.2 vs. + 0.2 +/- 10.1 mmHg) than group P (n = 26) (p < 0.05). Consumption of a packaged entree diet resulted in greater losses of weight and fat mass, and reduced BP. CONCLUSIONS: Use of packaged entrees as part of a weight-loss diet is an effective means of achieving portion control and enhancing losses of weight and fat mass in overweight men.

Photoreactivation of Pseudomonas cepacia after ultraviolet exposure: a potential source of contamination in ultraviolet-treated waters.

Cells of a naturally occurring strain of Pseudomonas cepacia grown in distilled water were exposed to ultraviolet radiation. Irradiated samples incubated on membrane filters or in fluid recovery media in the absence of light showed no evidence of dark repair mechanisms. When samples were exposed to fluorescent light ranging from 50 to 950 foot candles (538 to 10,222 lux) of illumination, apparent photo-induced repair of ultraviolet injury resulted in 1- to 4-log increases in viable cells recovered.

Efficacy of chemical dosing methods for isolating nontuberculous mycobacteria from water supplies of dialysis centers.

Investigations of nontuberculous mycobacterium (NTM) infections associated with various environmental sources have been hampered by the lack of adequate techniques for selective isolation of these organisms from environmental fluids. This study compared chemical dosing techniques for recovery of NTM from water samples collected from 115 randomly selected dialysis centers. Cell suspensions of NTM group II and IV isolates and gram-negative bacteria were exposed to solutions containing sodium hypochlorite (0.2 micrograms/ml of free available chlorine), formaldehyde (1, 0.75, or 0.5%), oxalic acid (1.25%), cetylpyridinium chloride (25 micrograms/ml), or cetyltrimethylammonium bromide (100 micrograms/ml). Results of standard membrane filtration assays with laboratory test strains and water samples from dialysis centers showed that 5 min of exposure to 1% formaldehyde effectively reduced gram-negative bacterial populations and allowed increased recovery of NTM in environmental fluids containing mixed microbial populations.

Factors that influence microbial contamination of fluids associated with hemodialysis machines.

Studies were conducted on the microbiological quality of fluids associated with different types of dialysis systems located in six dialysis centers and 14 homes. Included were (i) single-pass systems employing either parallel flow (Kiil or Gambro) or capillary cartridge dialyzers and (ii) recirculating single-pass and batch recirculating systems using coil dialyzers. Microbiological assays were performed on the water used to prepare dialysis fluid, the concentrated dialysate, and either pre- and postdialyzer dialysate (single-pass systems) or the dialysate contained in storage reservoirs and recirculating cannisters (recirculating systems). The levels of microbial contamination consisting of gram-negative bacteria were directly related to the type of dialysis system, method of water treatment, distribution system, and in some instances, the type of dialyzer. Recirculating single-pass and batch recirculating systems consistently contained significantly higher levels of contamination than single-pass systems. These results were directly related to the design of recirculating systems which permits carbon- and nitrogen-containing waste products dialyzed from the patient to accumulate, be used as nutrients by microorganisms, and subsequently allow for 2- to 4-log increases in contamination levels during a dialysis treatment. In contrast, levels of contamination in single-pass machines were related more to the quality of the water used to prepare dialysis fluid and the adequacy of cleaning and disinfection procedures than to the design of the system.

Morphological, biochemical, and growth characteristics of pseudomonas cepacia from distilled water.

Studies were conducted on three strains of Pseudomonas cepacia isolated and maintained in distilled water and on a laboratory-subcultured strain transferred to distilled water. Optimum growth rates and maximum population yields of the four strains in distilled water were obtained at 37 C, although high population levels (10(6)-10(7)/ml) were reached and maintained over extended incubation periods at temperatures from 18 C to 42 C. Two strains were able to grow in distilled water at temperatures ranging from 12 C to 48 C and to survive 48 h and 21 days at 50 C and 10 C, respectively. Cells from distilled water cultures inoculated into Trypticase soy broth showed an immediate two- to three-log drop at upper and lower temperature limits; survivors were able to initiate logarithmic growth. Results obtained in morphological, biochemical, and antibiotic tests affirmed the strain differences noted in growth studies.

Growth characteristics of atypical mycobacteria in water and their comparative resistance to disinfectants.

With the increasing significance of group IV atypical mycobacteria as etiological agents in a variety of infections, studies were conducted to determine their growth capabilities in water and their comparative resistance to disinfectants used to decontaminate hospital equipment. Isolates of Mycobaterium chelonei (TM strains) from peritoneal fluids of patients and peritoneal dialysis machines were able to multiply in commercial distilled water, with generation times at 25 degrees C ranging from 8 to 15 h. Levels of 10(5) to 10(6) cells per ml were attained, and these stationary-phase populations declined only slightly over a 1-year period. Results of studies to determine resistance to disinfectants showed the following. (i) TM strains of M. chelonei cultured in commercial distilled water showed survivors in 2% aqueous formaldehyde (HCHO) solutions up to 24 h; in 8% HCHO, only a 2-log reduction in viable counts was observed over a 2-h sampling period. Reference ATCC strains of M. chelonei and M. fortuitum were rapidly inactivated, with no survivors after 2 h of exposure to 2% HCHO or 15 min of exposure to 8% HCHO. (ii) In 2% alkaline glutaraldehyde, TM strains survived 60 min. whereas ATCC strains showed no survivors after 2 min of contact time. (iii) All M. chelonei and M. fortuitum strains survived 60 min of exposure to concentrations of 0.3 and 0.7 microgram of free chlorine per ml at pH 7.

Factors affecting comparative resistance of naturally occurring and subcultured Pseudomonas aeruginosa to disinfectants.

A strain of Pseudomonas aeruginosa was isolated in pure culture from the reservoir of a hospital mist therapy unit by an extinction-dilution technique; its natural distilled water environment was used as a growth and maintenance medium. After a single subculture on Trypticase soy agar, the strain showed a marked decrease in resistance to inactivation by acetic acid, glutaraldehyde, chlorine dioxide, and a quaternary ammonium compound when compared with naturally occurring cells grown in mist therapy unit water. The following factors were observed to affect the relative resistances of naturally occurring and subcultured cells of the P. aeruginosa strain: (i) temperature at which the cultures were incubated prior to exposure to disinfectants, (ii) growth phase of the cultures at the time of exposure to disinfectants, (iii) nature of the suspending menstruum for disinfectants, and (iv) exposure to fluorescent light during incubation of inocula prior to testing. The applied significance of these findings may alter the present concepts of disinfectant testing as well as routine control procedures in the hospital environment.

Comparative evaluation of selective media for isolation of Pseudomonas cepacia from cystic fibrosis patients and environmental sources.

Pseudomonas cepacia has recently emerged as an important pathogen affecting cystic fibrosis (CF) patients. We evaluated three selective media to assess their comparative potential for identification of patients colonized with P. cepacia and for efficacy of detection of P. cepacia in environmental fluids. Test organisms included P. cepacia isolates from CF patients (10 each from two CF centers), non-CF patients (10 isolates), and environmental sources (10 isolates). Microbiologic assays were done by the membrane filter procedure; filters were placed on P. cepacia medium (PCM), OFPBL, TB-T, MacConkey agar (MAC), and blood agar (BA) or Standard Methods (SM) sugar, and colonies were counted after incubation at 30 or 35 degrees C for 72 h. Mean recovery efficiencies (MREs) (mean CFU/ml on selective media compared with CFU/ml on BA controls) for environmental and non-CF P. cepacia and patient isolates from one CF center showed a rank order of PCM greater than OFPBL greater than TB-T; for isolates from a second CF center, a rank order of PCM greater than TB-T greater than OFPBL was obtained. MREs for CF center isolates were generally lower than for non-CF patients or environmental isolates on P. cepacia-selective media. With MAC, the MREs for each group of CF isolates were extremely low (14 and 2%) compared with those for non-CF patient (47%) or environmental (84%) isolates. In laboratory and field studies, PCM and OFPBL showed good selectivity against bacteria commonly associated with CF patient respiratory secretions. These findings show that selective media should be used in clinical settings where P. cepacia is sought. With environmental fluids from CF centers, P. cepacia-selective media showed low selectivity against a variety of gram-negative water bacteria and appeared to afford little advantage over SM agar for isolating P. cepacia from environmental samples.

Laboratory proficiency test results on use of selective media for isolating Pseudomonas cepacia from simulated sputum specimens of patients with cystic fibrosis.

Pseudomonas cepacia colonization of or infection in patients with cystic fibrosis (CF) has been associated with increased morbidity and premature death. However, current data on national incidence may be biased because of interlaboratory differences in the methods of culturing sputa of patients with CF. We conducted three tests to evaluate the proficiency of microbiology laboratories at CF centers in identifying and isolating P. cepacia and to assess the value of using selective media for P. cepacia (P. cepacia agar and oxidation-fermentation polymyxin-bacitracin-lactose medium [OFPBL]) to recover P. cepacia from specimens simulating sputa of patients with CF. In test 1, we evaluated the proficiency of laboratories in identifying P. cepacia. Of 111 laboratories tested, 105 (95%) correctly identified P. cepacia. In test 2, we evaluated the proficiency of laboratories in isolating P. cepacia from simulated CF sputum specimens. Only 36 (32%) of 115 laboratories detected P. cepacia. Recovery of the microorganism was associated with the use of P cepacia agar or OFPBL; 14 (95%) of 15 laboratories using P. cepacia agar or OFPBL (or both) versus 22 (22%) of 100 laboratories not using either medium recovered P. cepacia (P less than 0.0001, Fisher exact test, one tailed). Laboratories failing test 2 were requested to use a selective medium for P. cepacia in a repeat test; 73 (97%) of 75 laboratories using P. cepacia agar or OFPBL (or both) versus 0 of 4 laboratories not using either medium detected P. cepacia (P less than 0.0001, Fisher exact test, one tailed). Our studies show that (i) microbiology laboratories at CF centers are proficient in identifying P. cepacia, and (ii) the use of selective media for P. cepacia enhances recovery of the microorganism in simulated sputum specimens. Therefore, we recommend the use of selective media for P. cepacia in laboratories processing sputa of patients with CF.

Gram-negative water bacteria in hemodialysis systems.

Gram-negative bacteria can multiply relatively fast in a variety of hospital associated fluids ranging from distilled, deionized, reverse osmosis, and softened water, which are normally considered devoid of nutrients, to intravenous solutions and fluids associated with hemodialysis. Excessive levels of these bacteria in the dialysate of artificial kidney machines can be responsible for pyrogenic reactions or sepsis or both.