Pseudo-outbreak of Legionella pneumophila serogroup 8 infection associated with a contaminated ice machine in a bronchoscopy suite.

OBJECTIVE: To investigate the marked increase noted over an 8-month period in the number of Legionella pneumophila isolates recovered from bronchoalveolar lavage fluid specimens obtained during bronchoscopy in our healthcare system. SETTING: Bronchoscopy suite that serves a 580-bed tertiary care center and a large, multisite, faculty practice plan with approximately 2 million outpatient visits per year. METHODS: Cultures of environmental specimens from the bronchoscopy suite were performed, including samples from the air and water filters, bronchoscopes, and the ice machine, with the aim of identifying Legionella species. Specimens were filtered and acid-treated and then inoculated on buffered charcoal yeast extract agar. Serogrouping was performed on all isolates recovered from patient and environmental samples. RESULTS: All L. pneumophila isolates recovered from patients were serogroup 8, a serogroup that is not usually recovered in our facility. An epidemiologic investigation of the bronchoscopy suite revealed the ice machine to be contaminated with L. pneumophila serogroup 8. Patients were exposed to the organism as a result of a recently adopted practice in the bronchoscopy suite that involved directly immersing uncapped syringes of sterile saline in contaminated ice baths during the procedures. At least 1 patient was ill as a result of the pseudo-outbreak. Molecular typing of isolates recovered from patient and environmental samples revealed that the isolates were indistinguishable. CONCLUSIONS: Extensive cleaning of the ice machine and replacement of the machine's water filter ended the pseudo-outbreak. This episode emphasizes the importance of using aseptic technique when performing invasive procedures, such as bronchoscopies. It also demonstrates the importance of reviewing procedures in all patient areas to ensure compliance with facility policies for providing a safe patient environment.

Randomized double-blinded trial of rifampin with either novobiocin or trimethoprim-sulfamethoxazole against methicillin-resistant Staphylococcus aureus colonization: prevention of antimicrobial resistance and effect of host factors on outcome.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen in hospitals. Current antimicrobial regimens for eradicating colonizing strains are not well defined and are often complicated by the emergence of resistance. The combination of novobiocin plus rifampin in vitro and in vivo was found to prevent the emergence of resistant populations of initially susceptible strains of MRSA, particularly resistance to rifampin. We therefore studied, in a randomized, double-blind, multicenter comparative trial, the combination of novobiocin plus rifampin versus trimethoprim-sulfamethoxazole (T/S) plus rifampin in order to determine the efficacy of each regimen in eradicating MRSA colonization and to further characterize the host factors involved in the response to this antimicrobial therapy. Among the 126 individuals enrolled in the study, 94 (80 patients; 14 hospital personnel) were evaluable. Among the 94 evaluable subjects, no significant demographic or medical differences existed between the two treatment groups. Successful clearance of the colonizing MRSA strains was achieved in 30 of 45 (67%) subjects receiving novobiocin plus rifampin, whereas successful clearance was achieved in 26 of 49 (53%) subjects treated with T/S plus rifampin (P = 0.18). The emergence of resistance to rifampin developed more frequently in 14% (7 of 49) of subjects treated with T/S plus rifampin than in 2% (1 of 45) of subjects treated with novobiocin plus rifampin (P = 0.04). Restriction endonuclease studies of large plasmid DNA demonstrated that the same strain was present at pretherapy and posttherapy in most refractory cases (24 of 29 [83%] subjects). Among the 56 successfully treated subjects, clearance of MRSA was age dependent: 29 of 36 (80%) subjects in the 18- to 49-year-old age group, 19 of 35 (54%) subjects in the 50- to 69-year-old age group, and 8 of 23 (35%) in the 70- to 94-year-old age group (P < 0.01). Clearance was also site dependent; culture-positive samples from wounds were related to a successful outcome in only 22 (48%) of 46 subjects, whereas culture-positive samples from sites other than wounds (e.g., nares, rectum, and sputum) were associated with a success rate of 34 of 48 (71%) subjects (P = 0.02). Foreign bodies in wounds did not prevent the eradication of MRSA by either regimen. T/S plus rifampin was less effective in clearing both pressure and other wounds, whereas novobiocin plus rifampin was equally effective in clearing both pressure and other wounds. There were no significant differences in toxicity between the two regimens. Thus, the combination of novobiocin plus rifampin, in comparison with T/S plus rifampin, was more effective in preventing the emergence of resistance to rifampin and demonstrated a trend toward greater activity in clearing the MRSA carrier state. The response to either combination depended on host factors, particularly age and the site of MRSA colonization.

Methicillin-resistant Staphylococcus aureus: a consensus review of the microbiology, pathogenesis, and epidemiology with implications for prevention and management.

Methicillin-resistant Staphylococcus aureus (MRSA) has become a major nosocomial pathogen in community hospitals, long-term-care facilities, and tertiary care hospitals. The basic mechanism of resistance is alteration in penicillin-binding proteins of the organism. Methods for isolation by culture and typing of the organism are reviewed. MRSA colonization precedes infection. A major reservoir is the anterior nares. MRSA is usually introduced into an institution by a colonized or infected patient or health care worker. The principal mode of transmission is via the transiently colonized hands of hospital personnel. Indications for antibiotic therapy for eradication of colonization and treatment of infection are reviewed. Infection control guidelines and discharge policy are presented in detail for acute-care hospitals, intensive care and burn units, outpatient settings, and long-term-care facilities. Recommendations for handling an outbreak, surveillance, and culturing of patients are presented based on the known epidemiology.

An effective educational program to reduce the frequency of needle recapping.

We developed an educational program that reported the rate of needle recapping to healthcare workers, in conjunction with emphasis on appropriate disposal procedures. Over 12 months, the rate of recapping needles used for venipuncture and for percutaneous medication injections fell from 61% to 16% (p less than .0001). Over the same period, the recapping of needles used primarily for intravenous (IV) administration fell from 44% to 33% (p = .03). Re-evaluation of the rate of recapping eight months later showed a continuation of these lowered rates. Needlestick injuries were too few in number during the study period to detect any change accompanying the decreased recapping rate. We conclude that programs that report back to employees their rate of recapping can significantly reduce this activity in the disposal of needles used for venipuncture and for percutaneous medication injections. While such reporting may reduce the rate of recapping of needles used for IV administration, the effect is not nearly so marked. Modifications in design remain the most promising approach to preventing needlestick injuries from recapping needles used for IV administration.

Outbreak of multiply resistant Staphylococcus aureus in a pediatric intensive care unit after consolidation with a surgical intensive care unit.

Patients in a pediatric intensive care unit were placed with patients in an adult surgical intensive care unit (SICU) in a large, 12-bed room previously occupied exclusively by the adult patients. The occurrence of multiply resistant Staphylococcus aureus (MRSA) in pediatric patients increased from zero cases during the preceding 12 months to seven cases (p less than 0.001) for the 95 days that the units were combined. The rate of acquisition of MRSA by the patients in the SICU remained unchanged. Pediatric patients who acquired MRSA had longer lengths of stay (p less than 0.001) and underwent more surgical (p less than 0.01) and invasive procedures than did pediatric patients who did not acquire MRSA. Removal of the pediatric patients to their own unit returned their rate of MRSA acquisition to the previous low level.

Endemic, multiply resistant Staphylococcus aureus in a pediatric population. Clinical description and risk factors.

During a seven-year period, 38 children acquired multiply resistant Staphylococcus aureus (MRSA) after admission to a pediatric service. Eighteen children were thought to be colonized. Twenty-three infectious episodes occurred in the remaining 20 children. Infections included endocarditis (n = 2), pneumonia (n = 8), burn infection (n = 1), postoperative wound infection (n = 6), intra-abdominal abscess (n = 1), catheter sepsis (n = 2), urinary tract infection (n = 1), conjunctivitis (n = 1), and central nervous system shunt infection (n = 1). When patients infected with MRSA were compared by multivariate analysis with control subjects matched for age and unit of admission, patients with MRSA were hospitalized longer, underwent more surgical procedures, received more intravenous alimentation, and were more likely to require a tracheostomy; no correlation was found with administration of antibiotics. Twenty-six of the 34 discharged patients remained colonized with MRSA. Mortality in the infected patients was 20% (4/20), with a 38% (3/8) mortality rate for MRSA pneumonia.

Impact of a rigid, puncture resistant container system upon needlestick injuries.

Needlestick injuries in a 720-bed tertiary care hospital were analyzed before and after the introduction of a rigid, puncture resistant, needle disposal system. Following implementation of the system, disposal-related injuries decreased from 0.9 per 100 full-time equivalent employees/year to 0.3 per 100 full-time equivalent employees/year (p less than .005). However, needlesticks associated with procedures (2.2 vs. 4.4 per 100 full-time equivalent employees/year, p less than .0005), and those resulting from loose needles (0.5 vs. 1.9 per 100 full-time equivalent employees/year, p less than .0005), increased. Injuries occurring during needle recapping or the carrying of needles were not significantly altered. Total needlestick injuries increased from 6.0 to 8.7 per 100 full-time equivalent employees/year (p less than .0005). We concluded that a rigid, puncture resistant, needle disposal system can reduce disposal-related needlestick injuries, but must also be perceived as convenient to impact substantially upon needlesticks associated with other activities.

Strict versus modified isolation for prevention of nosocomial transmission of methicillin-resistant Staphylococcus aureus.

Patients colonized or infected with methicillin-resistant Staphylococcus aureus (MRSA) in a Surgical Intensive Care Unit and Surgical Intermediate Care Unit were placed either in Strict Isolation or cared for with modified isolation precautions. The assignment was determined by the unit in which they were hospitalized. Units were changed from one form of isolation to the other and served as their own controls. Over a 4-month study period, the rate of MRSA transmission did not change when the type of isolation precautions were altered. The ratio of colonized to infected patients also remained constant. Infected patients were usually first detected by clinical specimens, while colonized patients were usually detected by surveillance cultures performed under the study protocol. Following the study, all hospitalized patients with MRSA were placed in modified isolation precautions. Total new acquisitions of MRSA in the hospital have decreased over the subsequent 6-month period.

Empirical use of imipenem as the sole antibiotic in the treatment of serious infections.

Seventy-three patients with eighty-five infections were treated with imipenem as the sole antimicrobial agent. Some of these infections were caused by pseudomonads and enterococci resistant to other cephalosporins. The vast majority of the Gram-positive and the Gram-negative bacteria that were isolated had a minimal inhibitory concentration (MIC) of less than 1 mg/l, and all MICs for initial isolates were below the levels of imipenem that were achieved in plasma and other body fluids with a dose of 500 mg every 6 h. The outcomes of 67 infectious episodes were satisfactory, four outcomes were failures and 14 were not evaluable. During the two years of this study, only a few strains of Staphylococcus epidermidis and of Pseudomonas aeruginosa emerged which were resistant to imipenem.

Ceftizoxime elimination kinetics in continuous ambulatory peritoneal dialysis.

We investigated the kinetics of ceftizoxime, a beta-lactamase stable cephalosporin, in eight subjects undergoing continuous ambulatory peritoneal dialysis (CAPD). A single 500-mg or 1-gm dose was injected IV, or a 500-mg dose was given intraperitoneally in the CAPD fluid during a 6-hr dwell time. The ceftizoxime (500 mg) serum kinetic parameters were as follows: peak concentrations, 21 to 46 mg/l; volume of distribution, 0.27 l/kg; elimination rate constant, 0.0784 hr-1; plasma clearance, 1.66 l/kg hr-1; and t1/2, 10.2 hr. The t1/2 after 1 gm was 12 hr. Dialysate ceftizoxime concentrations rose rapidly between 0.25 and 2 hr and slowly over the next 4 hr, but only 4.04 +/- 1.8 and 7.4 +/- 2.9 mg ceftizoxime/hr was eliminated by the peritoneal route over a 6-hr dwell time after 500 mg or 1 gm IV. This represents only 4% to 5% of the dose. After intraperitoneal instillation, the antibiotic appeared in the serum within 15 min in all four subjects, and the peak serum concentrations ranged from 12 to 19.8 mg/l (mean +/- SD = 16.4 +/- 3.3) between 5 and 6 hr. Approximately 78% of ceftizoxime was absorbed from the peritoneal dialysis fluid during a single 6-hr dwell time. Rate constant for absorption, ka, was 0.3959 hr-1 and absorption t1/2 was 1.75 hr (as calculated by the residual equation). These data suggest that ceftizoxime has bidirectional exchange characteristics through the peritoneal membrane. Instillation of ceftizoxime in CAPD fluid alone may permit rapid absorption to reach therapeutic serum concentrations.

T lymphocyte abnormalities in disseminated histoplasmosis.

Disseminated histoplasmosis is associated with depression of T cell-mediated immunity and in some cases anergy. In this report, two patients with disseminated disease are described. Both had a depression of T cell-mediated immunity as well as other abnormalities of immune response. In one, a patient with relapse, a marked depression in the ratio of T helper to T suppressor cells was noted. Neither patient had any predisposing condition known to be associated with disseminated disease.

A randomized study comparing clinical efficacy and safety of thienamycin formamidine (MK0787)/renal dipeptidase inhibitor (MK0791) and cefazolin.

Twenty-one hospitalized patients with infectious diseases were randomly assigned to receive either thienamycin formamidine/renal dipeptidase inhibitor or cefazolin. Infections treated included septicaemia, pneumonia, osteomyelitis, pyelonephritis, cellulitis and cutaneous abscesses. All eleven patients treated with thienamycin formamidine/renal dipeptidase inhibitor responded well to therapy. One of the ten patients treated with cefazolin developed a superinfection with Pseudomonas aeruginosa. Side effects detected were minor in both groups.

Treatment of serious infections with moxalactam.

In 93 hospitalized patients, 111 bacterial infections were treated with moxalactam. Eighty-three infections responded well to therapy, nine infections failed to respond to therapy or relapsed, and nine infections showed superinfection with resistant bacteria. The great majority of bacteria isolated had mean inhibitory concentrations below levels readily achieved in plasma, cerebrospinal fluid, bile, abscess fluid, and peritoneal fluid. Among the commonly identified bacteria, only Pseudomonas aeruginosa, enterococci, and Staphylococcus epidermidis had variable sensitivity to moxalactam.

Osteomyelitis caused by viridans streptococci.

A 34-year-old man without known underlying disease was seen with osteomyelitis of the proximal shaft of the left femur. At operation, only viridans streptococci were isolated. The patient responded to a combination of intravenous penicillin G potassium and gentamicin sulfate therapy. To our knowledge, this is the first reported case of osteomyelitis of a long bone produced by hematogenous seeding by viridans streptococci.

Treatment of significant bacterial infections in adults with cefoxitin.

Cefoxitin is a new antimicrobial agent derived from cephamycin C. Fifty-four hospitalized patients with 63 clinically significant infections were treated with cefoxitin. Fifty-four infections (86%) were cured by therapy with cefoxitin alone or together with local therapy (i.e., heat, elevation, or surgical drainage). Six infections (10%) were not eradicated by the therapy used. Three patients could not be evaluated. Addition of oral probenecid therapy produced increases in levels of cefoxitin in serum and increased the inhibitory and bactericidal levels of cefoxitin in serum to more favorable ratios. Adverse side effects were seen in 19 patients and included positive direct Coombs' tests, increased eosinophil counts, skin rashes, vasculitis, phlebitis, elevation of liver enzymes, and drug-induced fever.

Oxolinic acid for the treatment of chronic gastrointestinal Shigella carriers.

Two patients were long-term gastrointestinal carriers of Shigella flexneri for 23 mo and 6 mo, respectively. Neither patient responded to oral antibiotics, despite in vitro sensitivity of the bacteria to the antibiotics administered. Oral oxolinic acid produced immediate cessation of the carrier state in both patients, with resolution of minor but persistent physical complaints.