Eradication of multi-drug resistant Acinetobacter from an intensive care unit.

BACKGROUND: Acinetobacter baumannii is a gram-negative coccobacillus that causes outbreaks of nosocomial infections in ICUs. Due to resistance to multiple antibiotics, management of clusters of A. baumannii is useful as a model in eradication of multi-drug resistant infections. We outline the evolution of an A. baumannii outbreak, focusing on methods of transmission and multidisciplinary measures aimed at eliminating it from the ICU. METHODS: Patients in an urban, tertiary care medical center from November 1996 to December 1997 having positive cultures for multi-drug resistant A. baumannii are included in this study. A. baumannii was isolated on blood agar and MacConkey cultures and identified by Vitek panel. Disk diffusion including amikacin, imipenem, polymyxin B, and sulbactam were used to determine resistance. RESULTS: An outbreak of 52 patients (27 infected, 25 colonized) with 68 positive sites began with the transfer of a colonized >50% total body surface area burn patient from an outside hospital. Within 3 days, the index patient was in the burn ICU, coronary care unit, and medical ICU. Soon, clusters of patients with A. baumannii infections sensitive only to polymyxin B were seen in those units and, ultimately, the surgical ICU. On typing, 2 strains were found, PFGE B and C. Given the level of antibiotic resistance, patients with colonization or infection were cohorted and placed on contact isolation. Strict antiseptic measures, such as hand-washing, barrier isolation, equipment and room cleaning, sterilization of ventilator equipment, and dedication of medical equipment to each patient were instituted. Still, positive environmental cultures were found in ventilator water traps, sinks, and bedrails. Sporadic cases continued for a total of 13 months, with 10 deaths resulting from the infections. CONCLUSION: A. baumannii is a mildly virulent organism that becomes resistant to antimicrobials. Because of multiple antibiotic resistance, strict contact isolation cohorting and antiseptic technique are the primary modes of containment. This outbreak serves as a model of eradication of multi-drug resistant organisms from ICUs. These measures will become of greater importance as nosocomial organisms develop increasing resistance to antimicrobials.

Nasal colonization by Staphylococcus aureus in active, independent, community seniors.

OBJECTIVE: to evaluate the prevalence of nasal colonization with Staphylococcus aureus (SA) in active, independent community seniors and old people in a nursing home. DESIGN: cross-sectional brief questionnaire and screening culture of anterior nares specimens from 165 elders at a community centre and cross-sectional data from a recent survey in a nursing home. RESULTS: the prevalence of SA colonization in community seniors (27%) was similar to that in the nursing home (29%). The proportion of SA isolates that were methicillin-resistant was much lower in the community seniors (2.3%) than in the nursing-home residents (31%). There was less antibiotic resistance in those living at home. CONCLUSION: in community seniors the prevalence of SA colonization was similar to that in nursing-home residents, but the prevalence of methicillin-resistant SA was lower. Susceptibility patterns of antibiotics tested against the SA showed less resistance than isolates from nursing-home patients.

Willingness to treat HIV-positive patients at different stages of medical education and experience.

The willingness of physicians to provide care to HIV-positive patients has been linked to a number of attitudinal factors, but little is known concerning the impact of premedical, medical, and residency training on these factors. The purpose of this study is to elicit responses to the same series of questions concerning HIV and its treatment from respondents at different stages of training, to detect trends in attitudes and to measure the impact of those attitudes on willingness to provide care for HIV/AIDS patients. Study data come from a cross-sectional survey (n = 249) of respondents across the training continuum, from premedical students to faculty physicians, using a self-administered questionnaire at a single medical school. The response rate was 59.6%. The study showed significant decreases in personal fear and misgivings concerning HIV, coupled with a substantial decrease in the perceived need for testing of non-high-risk individuals, as respondents gained additional education and training. Overall, the intent to treat HIV did not change significantly by training level, but multivariate analyses showed that while the initially strong influence of attitudes toward AIDS and its attendant risks diminishes, comfort relative to being around homosexuals per se continues to exert an impact on the intent to treat. Appropriate use of protective measures when providing care becomes far more common once individuals enter their clinical training years. The impact of medical education through its entire continuum therefore shows a positive impact on attitudes toward HIV, despite the absence of a significant trend in respondents' stated intent to treat. However, negative attitudes toward homosexuals continue to exert a negative influence on intent to treat that endures into the clinical training years.

Infection surveillance and antibiotic utilization in a community-based skilled nursing facility.

To survey the types of suspect infections, the antibiotic utilization and the patterns of antibiotic resistance among bacterial pathogens in a community Skilled Nursing Facility (SNF), we conducted a 20-month prospective observational surveillance program comprising all 585 patients admitted to a 149-bed private community SNF. Data were collected form medical charts, laboratory reports and nurses reports. Overall, 41% of the patients developed at least one presumptive nosocomial infection, and 54% of the patients received one or more antibiotic treatments. The overall presumptive nosocomial infection rate was 7.2 per 1000 patient days. The most common sites of presumptive nosocomial infection were the urinary tract (38%) and the respiratory tract (28%). The most common pathogens overall were E. coli (25%). Antibiotic groups used most frequently were the quinolones (22% of prescriptions). Thirty-nine percent of the Staphylococcus aureus isolates associated with suspected infections were resistant to methicillin, and of these 94% were also resistant to ciprofloxacin. Most of the resistant S. aureus isolates were from indwelling catheter-associated with UTIs. Infections associated with quinolone resistant strains of gram-negative bacilli were infrequent. No epidemiologic evidence of nosocomial clustering was apparent.

Antimicrobial resistance in long-term-care facilities.

During the last quarter century, numerous reports have indicated that antimicrobial resistance commonly is encountered in long-term-care facilities (LTCFs). Gram-negative uropathogens resistant to penicillin, cephalosporin, aminoglycoside, or fluoroquinolone antibiotics and methicillin-resistant Staphylococcus aureus have received the greatest attention, but other reports have described the occurrence of multiply-resistant strains of Haemophilus influenzae and vancomycin-resistant enterococci (VRE) in this setting. Antimicrobial-resistant bacteria may enter LTCFs with colonized patients transferred from the hospital, or they may arise in the facility as a result of mutation or gene transfer. Once present, resistant strains tend to persist and become endemic. Rapid dissemination also has been documented in some facilities. Person-to-person transmission via the hands of healthcare workers appears to be the most important means of spread. The LTCF patients most commonly affected are those with serious underlying disease, poor functional status, wounds such as pressure sores, invasive devices such as urinary catheters, and prior antimicrobial therapy. The presence of antimicrobial-resistant pathogens in LTCFs has serious consequences not only for residents but also for LTCFs and hospitals. Experience with control strategies for antimicrobial-resistant pathogens in LTCFs is limited; however, strategies used in hospitals often are inapplicable. Six recommendations for controlling antimicrobial resistance in LTCFs are offered, and four priorities for future research are identified.

General guidelines for clinical bacteriology. Infectious Diseases Society of America and the Food and Drug Administration.

This guideline summarizes recommendations for (1) developing cogent procedures for diagnosis and antimicrobial susceptibility testing; (2) developing quality-control parameters for the microbiological components of clinical trials; (3) continually updating U.S. Food and Drug Administration (FDA) guidelines; (4) reviewing microbiological recommendations from other groups, such as Microbiology Subcommittees of the National Committee for Clinical Laboratory Standards; and (5) improving the microbiological aspects of FDA package inserts for antimicrobial drugs. Sensitive and specific methods for isolation and identification of pathogens are essential to the proper conduct of clinical trials. Susceptibility tests should be performed in an accurate and reproducible fashion. Verification of results in a reference laboratory is encouraged to monitor quality control.

Nosocomial infection and antibiotic utilization in geriatric patients: a pilot prospective surveillance program in skilled nursing facilities.

Prospective surveillance of nosocomial infection was conducted at seven skilled proprietary nursing facilities in Orange County, Calif., USA. The average incidence of facility-acquired infection was 5.2 infections/1,000 patient days. The most common source of infection was urinary tract (47%), followed by respiratory tract (26%) and skin (14%). The four most common pathogens isolated were Proteus spp. (20%), Escherichia coli (17%), Staphylococcus aureus (13%) and Pseudomonas spp. (11%). Trimethoprim-sulfamethoxazole (20%) was the most frequently used antibiotic among all prescriptions, followed by ampicillin (16%) and ciprofloxacin (14%). Among all residents surveyed, 33% received at least one course of antibiotics during the study. Of special significance was the fact that 4 (22%) of the 18 strains of Pseudomonas were gentamicin resistant as were 12 of 80 (15%) of the strains of Enterobacteriaceae. Furthermore, 9 of 29 (31%) strains of Pseudomonas tested were found resistant to norfloxacin as were 15 of 129 (12%) strains of enterobacteriaceae. Susceptibility patterns of the isolated pathogens were similar to those of the acute care hospital. This study indicates that infection continues to be a major problem in the skilled nursing facility and that antibiotic-resistant pathogens will be a challenge for the future.

Effect of oral contraceptives on leukocyte phagocytic activity and plasma levels of prostaglandin E2 and thromboxane B2 in normal menstruating women.

Mononuclear and polymorphonuclear cells were isolated from the peripheral blood of normal menstruating women. Four of the subjects were not using oral contraceptives and five were taking various formulations. The women were tested once a week for 12 consecutive weeks. Plasma levels of 6-keto-prostaglandin F2 alpha (6-KF), prostaglandin E2 (PGE2), thromboxane B2 (TxB2), estrogen, and progesterone were measured by specific radioimmunoassays. The phagocytic activity of the mononuclear and polymorphonuclear cells isolated from the peripheral blood was measured with a bacterial phagocytosis and killing assay. The phagocytic activity of both types of cells was depressed perimenstrually in both groups of women. However, examination of individuals showed that those subjects not taking oral contraceptives had a worsening of phagocytic activities with approaching menses while the oral contraceptive subjects generally had an improving of these activities at this time. We were unable to correlate the phagocytic activities with either hormone or prostaglandin levels in the plasma of these subjects. However, the subjects on oral contraceptives had significantly lower levels of PGE2 and TxB2 than those women who were not using oral contraceptives.

Sulbactam kinetics and excretion into breast milk in postpartum women.

We gave intravenous infusions of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin or cephalothin to women 2 days after cesarean section delivery. The elimination t1/2 was 1.0 hours, the volume of distribution at steady state was 268 ml/kg, and renal clearance was 295 ml/min. These values are similar to those in normal young men and in surgical patients and suggest that dose regimens of sulbactam will not need adjustment in the postpartum period. Sulbactam concentrations in breast milk averaged 0.5 micrograms/ml, a value similar to that of several beta-lactam antibiotics.

Depressed mononuclear cell phagocytic activity associated with menstruation.

The peak of the normal distribution curve for pelvic inflammatory disease occurs near the onset of menses. This study was undertaken to determine if there were changes in the cell-mediated immunity of normal menstruating women which could explain the increase in inflammatory disease. The cellular immune response of 8 normal women, measured by number of T- and B-cells and response of mononuclear cells to stimulation with mitogen, was not dependent on the menstrual cycle. However, there was a significant decrease in phagocytic activity of mononuclear cells early in the cycle. The depressed phagocytic activity was not altered by treating the subjects with ibuprofen.

Bacterial meningitis in the elderly.

To assess the implications of meningitis in a more mature population, we reviewed the records of patients with meningitis: 71 aged 50 years and older and 138 patients aged 15 to 49 years. Among the older population, 54 (76%) had bacterial, nine (13%) had granulomatous, and eight (11%) had aseptic meningitis. Among the cases of bacterial meningitis in the older age group, Streptococcus pneumoniae accounted for 24% (13/54) and enteric bacilli accounted for 17% (9/54). Serious complications occurred in 38 elderly patients (70%) with bacterial meningitis, and mortality occurred in 24 (44%). In the younger age group with bacterial meningitis, the complication rate and mortality were 41% (13/32) and 13% (4/32), respectively. Meningitis in the elderly is likely to be bacterial and to cause greater morbidity and mortality.

Splash basin contamination in orthopaedic surgery.

Samples of splash basin fluid were cultured at the end of 78 randomly selected orthopedic operations. Fifty-eight (74%) of the specimens were positive on culture. Staphylococcus epidermidis was the prevalent organism. Thirty-four (59%) of the positive cultures grew multiple organisms. Seven (12%) grew more than 100 colonies per 100 ml specimen. This study demonstrates that splash basin fluid is frequently contaminated and may be a source of wound contamination during orthopedic surgery. Implants should not be placed in the splash basin, and instruments placed in it should not be returned to the operative wound.

Reflux gastritis syndrome. Role of upper gastrointestinal microflora.

Bacteriologic samplings of the upper gastrointestinal tract bile acids profile of the intestinal contents were performed in eight patients with reflux gastritis syndrome and three asymptomatic patients who had had gastric surgery. All symptomatic patients showed colonization of the gastric and/or intestinal samples with strains of enteric Gram-negative bacteria and Pseudomonas. However, no single specific group or species was consistently associated with reflux gastritis syndrome. The concentration of total and conjugated bile acids was significantly greater in symptomatic patients. Presence of free bile acids was correlated with heavier bacterial colonization. To evaluate the effect of antibiotic therapy on bacterial flora and symptoms, patients were studied for three separate four-week evaluation periods. Following the first evaluation period, they were assigned to receive either doxycycline or placebo in a crossover fashion during the second and third periods. Total symptom scores did not differ significantly and no specific patterns were evident in the bacterial flora. These observations support the hypothesis that microbial flora is an associated factor in reflux gastritis syndrome and may play an important role only in certain individual patients.

Evaluation of urine culture screening by light-scatter photometry.

Urine screening for bacteriuria by light-scatter photometry (Autobac) was evaluated for accuracy and compared with a colony count by the calibrated loop method. Incubation time, inoculum size, precision, and interference of particulate matter were evaluated in an effort to standardize the screening procedure. Results showed that urines could be accurately screened for Enterobacteriaceae by inoculating a single Autobac cuvette chamber with 0.1 or 0.2 ml of urine and determining the voltage change after four hours. A change of greater than or equal to 0.2 units indicates significant bacteriuria. Decreased accuracy was noted for urines having greater than 10(5) cfu/ml of Pseudomonas species or gram-positive cocci, possibly because these organisms grow more slowly.

Effect of antimicrobial agents on human polymorphonuclear leukocyte microbicidal function.

The effect of 19 antimicrobial agents on human polymorphonuclear leukocyte function was evaluated by chemiluminescence assays, yeast phagocytosis and killing, and lactate dehydrogenase release. Tetracycline and trimethoprim inhibited chemiluminescence and reduced killing at therapeutic concentrations of 2 microgram/ml. Cephalothin inhibited yeast killing at a concentration of 20 microgram/ml, but a significant depression of polymorphonuclear leukocyte chemiluminescence was encountered only at higher levels of 200 microgram/ml. The inhibition shown by these drugs was reversible. None of the other antimicrobial agents tested demonstrated inhibition of chemiluminescence, phagocytosis, or killing at usual clinical serum levels. No antimicrobial agent tested caused release of lactate dehydrogenase from polymorphonuclear leukocytes. The results suggest that therapeutic concentrations of tetracycline, trimethoprim, and cephalothin may inhibit optimal polymorphonuclear leukocyte microbicidal function.

Quality control limits for ampicillin, carbenicillin, mezlocillin, and piperacillin disk diffusion susceptibility tests: a collaborative study.

A multilaboratory in vitro study was carried out to determine disk diffusion susceptibility testing quality control limits for two new semisynthetic penicillins, mezlocillin and piperacillin. Existing limits for carbenicillin and ampicillin were reevaluated. Multiple tests (which followed standards set by the National Committee for Clinical Laboratory Standards ASM-2 revised) were performed in nine laboratories by different technologists using disks and Mueller-Hinton agar from different manufacturers. Clinically significant differences between disks produced by different manufacturers were not noted. Inhibitory zone diameter measurements from all laboratories were analyzed, and upper and lower control limits were established by using the overall median +/-0.5 the median range of the individual laboratory measurements as determining parameters. Close agreement of the data in this study with the results of national proficiency testing and quality control programs for ampicillin and carbenicillin supports the validity of our approach to making initial recommendations for quality control guidelines for new antimicrobial agents.

Unique temperature-sensitive nutritional requirements of bacteremic Escherichia coli isolates.

Of 50 strains of Escherichia coli isolated from blood cultures of bacteremic patients, 14 (28%) were unable to grow on minimal medium at 42 degrees C, compared to only 2 of 50 nonbacteremic strains. In 7 of the 14 bacteremic strains, growth at 42 degrees C was restored by adding nicotinic acid. These unique temperature-sensitive auxotrophic patterns warrant evaluation as a marker correlating with clinical pathogenicity in E. coli.