The order of vasopressor discontinuation and incidence of hypotension: a retrospective cohort analysis

The optimal order of vasopressor discontinuation during shock resolution remains unclear. We evaluated the incidence of hypotension in patients receiving concomitant vasopressin (VP) and norepinephrine (NE) based on the order of their discontinuation. In this retrospective cohort study, consecutive patients receiving concomitant VP and NE infusions for shock admitted to intensive care units were evaluated. The primary outcome was hypotension incidence following discontinuation of VP or NE (VP1 and NE1 groups, respectively). Secondary outcomes included the incidence of acute kidney injury (AKI) and arrhythmias. Subgroup analysis was conducted by examining outcomes based on the type of shock. Of the 2,035 included patients, 952 (46.8%) were VP1 and 1,083 (53.2%) were NE1. VP1 had a higher incidence of hypotension than NE1 (42.1% vs. 14.2%; P < 0.001), longer time to shock reversal (median: 2.5 vs. 2.2 days; P = .009), higher hospital [29% (278/952) vs. 24% (258/1083); P = .006], and 28-day mortality [37% (348/952) vs. 29% (317/1,083); P < 0.001] when compared with the NE1 group. There were no differences in ICU mortality, ICU and hospital length of stay, new-onset arrhythmia, or AKI incidence between the two groups. In subgroup analyses based on different types of shock, similar outcomes were observed. After adjustments, hypotension in the following 24 h and 28-day mortality were significantly higher in VP1 (Odds ratios (OR) 4.08(3.28, 5.07); p-value < .001 and 1.27(1.04, 1.55); p-value < .001, respectively). Besides, in a multivariable model, the need for renal replacement therapy (OR 1.68 (1.34, 2.12); p-value < .001) was significantly higher in VP1. Among patients with shock who received concomitant VP and NE, the VP1 group was associated with a higher incidence of hypotension in comparison with NE1. Future studies need to validate our findings and their impact on clinical outcomes.

The Prevalence and Clinical Significance of Preoperative Thrombocytopenia in Adults Undergoing Elective Surgery: An Observational Cohort Study

BACKGROUND

Preoperative thrombocytopenia is associated with inferior outcomes in surgical patients, though concurrent anemia may obfuscate these relationships. This investigation assesses the prevalence and clinical significance of preoperative thrombocytopenia with thorough consideration of preoperative anemia status.

METHODS

This is an observational cohort study of adults undergoing elective surgery with planned postoperative hospitalization from January 1, 2009 to May 3, 2018. Patients were designated into 4 groups: normal platelet and hemoglobin concentrations, isolated thrombocytopenia (ie, platelet count <100 × 109/L), isolated anemia (ie, hemoglobin <12 g/dL women, <13.5 g/dL men), and thrombocytopenia with anemia. Thrombocytopenia was further defined as incidental (ie, previously undiagnosed) or nonincidental. Multivariable regression analyses were utilized to assess the relationships between thrombocytopenia status and clinical outcomes, with a primary outcome of hospital length of stay.

RESULTS

A total of 120,348 patients were included for analysis: 72.3% (95% confidence interval [CI], 72.1-72.6) normal preoperative laboratory values, 26.3% (26.1-26.6) isolated anemia, 0.80% (0.75-0.86) thrombocytopenia with anemia, and 0.52% (0.48-0.56) isolated thrombocytopenia (0.38% [0.34-0.41] nonincidental, 0.14% [0.12-0.17] incidental). Thrombocytopenia was associated with longer hospital length of stay in those with concurrent anemia (multiplicative increase of the geometric mean 1.05 [1.00, 1.09] days; P = .034) but not in those with normal preoperative hemoglobin concentrations (multiplicative increase of the geometric mean 1.02 [0.96, 1.07] days; P = .559). Thrombocytopenia was associated with increased odds for intraoperative transfusion regardless of anemia status (nonanemic: 3.39 [2.79, 4.12]; P < .001 vs anemic: 2.60 [2.24, 3.01]; P < .001). Thrombocytopenia was associated with increased rates of intensive care unit (ICU) admission in nonanemic patients (1.56 [1.18, 2.05]; P = .002) but not in those with preoperative anemia (0.93 [0.73, 1.19]; P = .578).

CONCLUSIONS

Preoperative thrombocytopenia is associated with clinical outcomes in elective surgery, both in the presence and absence of concurrent anemia. However, isolated thrombocytopenia is rare (0.5%) and is usually identified before preoperative testing. It is unlikely that routine thrombocytopenia screening is indicated for most patients.

Intravenous Versus Oral Acetaminophen in Outpatient Cystoscopy Procedures: Retrospective Comparison of Postoperative Opioid Requirements and Analgesia Scores

PURPOSE

To assess if the choice of acetaminophen formulation (intravenous vs oral) when administered preoperatively for ambulatory cystoscopy procedures is associated with differences in anesthetic outcomes.

METHODS

Medical records of adult patients undergoing ambulatory cystoscopy procedures at an outpatient procedural center from July 1, 2014, through November 30, 2017, were abstracted. The association between anesthetic outcomes (severe pain, rescue opioids, postoperative nausea, and vomiting) and acetaminophen formulation was assessed. Propensity-adjusted analyses were performed using inverse probability of treatment weighting to account for potential confounders.

RESULTS

During the study time frame, there were 611 intravenous and 2955 oral acetaminophen administrations for cystoscopy procedures. Postoperative bladder spasms were a major contributor to severe pain and complicated 1036 cases, with similar rates between intravenous (N = 183, 29.9%) and oral (N = 853, 28.9%) formulations, P = .625. After adjusting for bladder spasms, intravenous acetaminophen was associated with longer anesthesia recovery (estimate 5.2 [95% CI 0.5-9.9] minutes, P = .030), use of rescue opioids (odds ratio 1.33 [1.07-1.66], P = .012), and postoperative nausea and vomiting (1.40 [1.02-1.93], P = .037), but not severe pain (1.07 [0.81-1.40], P = .640).

CONCLUSION

Preoperative intravenous acetaminophen compared to oral acetaminophen for ambulatory cystoscopy procedures was not associated with better anesthetic outcomes. Bladder spasms were a major contributor to postoperative pain.

Ocular injury during spine surgery

PURPOSE

Ocular injury and vision loss are rare complications of surgery. Spine surgery has been identified as particularly high risk for postoperative vision loss; nevertheless, ocular injuries have not been comprehensively assessed in this patient population.

METHODS

This historical cohort study assessed incidence, cause, and risk factors of perioperative ocular injury after spine surgery at a tertiary care medical centre from January 1, 2006 through January 31, 2018. Patients were included who had ocular injury identified during an ophthalmology consultation in the first seven postoperative days. Differences in demographic, laboratory, intraoperative, and postoperative characteristics between those experiencing or not experiencing ocular injury were assessed with Fisher exact and Wilcoxon signed-rank tests for categorical and continuous variables, respectively.

RESULTS

Of 20,128 qualifying spine surgeries, 39 cases of perioperative ocular injuries were identified (39/20,128; 0.19% [95% confidence interval (CI), 0.14 to 0.26]). The most common ocular injury was blurry vision of unknown cause (13/39; 33%; 95% CI, 18.6 to 46.4), followed by ischemic optic neuropathy (9/39; 23%; 95% CI, 12.6 to 38.3) and corneal abrasion (7/39; 18%; 95% CI, 9.0 to 32.7). All cases of blurry vision of unknown cause were diagnosed via ophthalmology consultation and resolved within several days. Patients with perioperative ocular injury were more likely to have baseline anemia, have undergone fusion and instrumentation procedures, and had longer operative times with greater crystalloid, colloid, and transfusion requirements and more blood loss.

CONCLUSIONS

Although not representing a causal relationship, these data suggest that surgical factors may have a greater role than demographic characteristics or other clinical factors in the development of perioperative ocular injury. Surgeons, anesthesiologists, and patients should be aware of the increased risk of ocular injury that accompanies longer, more extensive spine operations.

Alendronate inhibits VEGF expression in growth plate chondrocytes by acting on the mevalonate pathway

Bisphosphonates decrease chondrocyte turnover at the growth plate and impact bone growth. Likewise vascular endothelial growth factor (VEGF) plays an important role in endochondral bone elongation by influencing chondrocyte turnover at the growth plate. To investigate whether the action of bisphosphonate on the growth plate works through VEGF, VEGF protein expression and isoform transcription in endochondral chondrocytes isolated from growing mice and treated with a clinically used bisphosphonate, alendronate, were assessed. Alendronate at 10µM and 100µM concentrations decreased secreted VEGF protein expression but not cell associated protein. Bisphosphonates are known to inhibit the mevalonate intracellular signaling pathway used by VEGF. Addition of the mevalonate pathway intermediates farnesol (FOH) and geranylgeraniol (GGOH) interacted with the low concentration of alendronate to further decrease secreted VEGF protein whereas FOH partially restored VEGF protein secretion when combined with the high alendronate. Similar to the protein data, the addition of alendronate decreased VEGF mRNA isoforms. VEGF mRNA levels were rescued by the GGOH mevalonate pathway intermediate at the low alendronate dose whereas neither intermediate consistently restored the VEGF mRNA levels at the high alendronate dose. Thus, the bisphophonate alendronate impairs growth plate chondrocyte turnover by down-regulating the secreted forms of VEGF mRNA and protein by inhibiting the mevalonate pathway.

Bisphosphonate treatment in the oim mouse model alters bone modeling during growth

Osteogenesis imperfecta (OI) is a heritable disease, which results from an abnormal amount or structure of Type I collagen. Bisphosphonates, a class of synthetic antiresorptive drugs, used in osteoporosis management, are also used to decrease fracture incidence and improve quality of life in children with OI. In this study, we used the oim mouse to test the hypotheses that pamidronate treatment during active growth (1) produces larger, stronger, stiffer long bone diaphyses without altering bone material properties, and (2) negatively impacts longitudinal bone growth. Our results indicate that femoral cross-sectional moment of inertia in the distal metaphysis tended to increase with pamidronate treatment and that the treated bones are thicker and structurally stiffer, but shorter than their control-dose counterparts.

Long Term Cyclic Pamidronate Reduces Bone Growth by Inhibiting Osteoclast Mediated Cartilage-to-Bone Turnover in the Mouse

Bisphosphonates, used to treat diseases exhibiting increased osteoclast activity, reduce longitudinal bone growth through an as yet undefined mechanism. Pamidronate, an aminobisphosphonate, was given weekly to mice at 0, 1.25, or 2.50 mg/kg/wk beginning at 4 weeks of age. At 12 weeks of age, humeral length, growth plate area, regional chondrocyte cell numbers, chondrocyte apoptosis, TRAP stained osteoclast number, and osteoclast function assessed by cathepsin K immunohistochemistry were quantified. Humeral length was decreased in pamidronate treated mice compared to vehicle control mice, and correlated with greater growth plate areas reflecting greater proliferative and hypertrophic chondrocyte cell numbers with fewer hypertrophic cells undergoing apoptosis. Pamidronate treatment increased TRAP stained osteoclast numbers yet decreased cathepsin K indicating that pamidronate repressed osteoclast maturation and function. The data suggest that long term cyclic pamidronate treatment impairs bone growth by inhibition of osteoclast maturation thereby reducing cartilage-to-bone turnover within the growth plate.

Alendronate affects long bone length and growth plate morphology in the oim mouse model for Osteogenesis Imperfecta

Alendronate, a bisphosphonate drug, has shown promise in reducing remodeling and bone loss in postmenopausal osteoporosis. Alendronate acts directly on the osteoclast, inhibiting its resorption capability. This inhibition of osteoclast activity has led to the use of bisphosphonates in the treatment of the osteogenesis imperfecta condition. Treatment of osteogenesis imperfecta with bisphosphonates enhances bone strength, but the consequences on linear bone growth are not well defined. Using the oim mouse model for type III osteogenesis imperfecta, two doses of alendronate, low (0.125 mg/kg/wk) and high (2.5 mg/kg/wk) were administered weekly via intraperitoneal injection starting at 4 weeks of age and ending at 12 weeks of age to assess the effects of alendronate on humerus and ulna length. The higher dose of alendronate reduced humerus and ulna length in the oim/wt and wt/wt genotypes for both sexes (P < 0.05). The oim/oim humerus and ulna were not significantly affected by the higher dose of alendronate in females, but reduced bone length in males (P < 0.0085). Proximal humerus growth plate area was affected by both genotype and alendronate dose and growth plate diameter was increased at the chondro-osseous junction by both alendronate doses (P < 0.011). Genotype and alendronate dose affected growth plate height. The oim/oim genotype displayed taller growth plates. The high dosage of alendronate increased overall growth plate height, particularly within the hypertrophic zone, which suggests a failure of vascular invasion-induced apoptosis in the hypertrophic cells. In conclusion, these results indicate that high doses of alendronate (>2.5 mg/kg/wk) inhibit long bone length in mice through alteration of the growth plate and possibly reduced resorption at the chondro-osseous junction.

Effects of pre and antenatal elevated and chronic oMt1a-oGH transgene expression on adipose deposition and linear bone growth in mice

Exposing growing oMtla-oGH transgenic mice with the regulatable metallothionein promotor to elevated growth hormone (GH) for three weeks after weaning enhances bone length and adipocyte differentiation. The objective of the present study was to investigate the consequences of highly elevated GH exposure during fetal and early postnatal growth periods on the mature phenotype. Transgene expression, hence elevated GH, was achieved in fetuses and neonates by providing 25 mM ZnSO4 to the drinking water of the dams. Wildtype and oMtla-oGH male and female mice were a) never exposed to the transgene stimulus, b) exposed from birth to 21 d of age, c) exposed through gestation until 21 d of age, d) exposed only through gestation, or e) exposed only during the first 7 d postpartum. At 84 d of age when mature body size was reached, ulna and humerus lengths, and body, liver gonadal fat pad, mesenteric fat pad, and cleaned gastrointestinal (GI) tract weights were recorded. Bone lengths were also determined in a subset of mice at 22 d of age. While early exposure to the elevated GH increased ulna and humerus length at 22 d of age, the early GH levels failed to produce significant changes in adipose content or bone lengths at maturity. However, chronic exposure to slightly elevated GH, as seen in the transgenics never induced to express the transgenic GH, depressed liver and GI weights and increased adipose depot weights and humerus lengths across both sexes. These results suggest that certain tissues in the body, while capable of responding to GH during early developmental periods, are not fully entrained to sustain that growth response once the GH stimulus is withdrawn. Further, the preadipocyte pool appears unable to respond to GH early in development. Finally, the tissues examined exhibited a differential response to the GH suggesting that different tissues possess distinct response thresholds.

Seated mammography for older patients

Standing for a mammography exam is difficult for some elderly patients due to dizziness, loss of strength or other age-related changes. This article reports on a pilot study that examined seated mammography as an alternative for older women. Results indicate that seated and standing mammography produced images of comparable quality and patients were equally satisfied with the procedures. The author advocates further investigation with a larger cohort of patients.

Hemispheric asymmetries in the resolution of lexical ambiguity

The linguistic phenomenon of lexical ambiguity has been intensively investigated as a means of gaining insight into general mechanisms of lexical access. It is now evident that both context and meaning frequency are significant factors in the determination of lexical outcomes. This suggests that hemispheric processes may be relevant to the resolution of lexical ambiguity, because both factors have been shown to have differential implications for the processing of language in the hemispheres. This study set out to examine the effects of context and meaning frequency on the resolution of ambiguous word meanings within the hemispheres. Sentences presented at the beginning of each trial embodied contexts which expressed either the dominant or subordinate meaning of a terminating homographic prime. Laterally presented target words reflected senses of the prime which were either consistent with, or inconsistent with, the context created by the preceding sentence. The most interesting results were observed at short prime-target intervals where it was found that although dominant meanings of the target did not give rise to visual field differences, subordinate meanings evoked facilitated responses only in the left visual field. This result suggests that the right hemisphere immediately and exhaustively activates the various meanings associated with a word, while in the left hemisphere initial access is selectively restricted to the dominant meaning. It is proposed that this reflects a model of language comprehension in which the right hemisphere plays a supportive role by making available a set of alternative and less probable word meanings, thus freeing the left hemisphere to focus cognitive resources upon the most probable meaning of a word in a given context.

Carrying out biological qualification, the control operation of moist-heat (steam sterilization) processes for producing sterile pharmaceuticals and medical devices

In this report we will first discuss the principles behind the practices that are used today in the design and qualification of moist-heat (steam sterilization) microbial-control processes used to produce sterile pharmaceutical products and medical devices. Secondly, we will work through example applications of how to design and qualify processes of three levels of complexity which we call Empirical Overkill, Empirical, and Product Specific. Empirical Overkill is specifically for the microbial-control processes for indirect items, such as tanks, pipes, pumps and other hardware. Empirical is for pharmaceutical and medical-device products that are produced under good manufacturing conditions and, therefore, there is control of the level of the microbial bioburden. Product Specific is for microbial-control processes designed and qualified for a specific product on the basis of the numbers and resistance of the bioburden of that product. We will treat design in this report; however, the major thrust is in setting up and carrying out the biological qualification of the process, which is the mode of control used to assure the adequacy of these microbial-control processes.

A pilot study of combination therapy with indinavir, stavudine (d4T), and didanosine (ddI) in children infected with the human immunodeficiency virus

Twelve children infected with the human immunodeficiency virus were treated orally with indinavir, stavudine, plus didanosine for 12 to 48 weeks. Therapy was limited in some cases by nonadherence, intolerance, toxicity, and virologic failure. Marked increases in CD4+ lymphocyte counts and decreases in plasma human immunodeficiency virus RNA concentrations suggest that the regimen has potent antiviral activity.

Observation of Raman scattering by cloud droplets in the atmosphere

In a recent field campaign, the NASA Goddard Space Flight Center scanning Raman lidar measured, in the water vapor channel, Raman scattering from low-level clouds well in excess of 100% relative humidity. The excess scattering has been interpreted to be spontaneous Raman scattering by liquid water in the cloud droplets. A review of research on Raman scattering by microspheres indicates that the technique may provide a remote method to observe cloud liquid water. The clouds studied appear, from Mie scattering, to have two distinct layers with only the upper layer showing significant Raman scattering from liquid water in the droplets.

Upper tropospheric temperature measurements with the use of a Raman lidar

Upper tropospheric temperature profiles were measured with the NASA Goddard Space Flight Center scanning Raman lidar five months after the eruption of Mt. Pinatubo. To derive temperatures in regions of high aerosol content, the aerosol transmission is calculated for the Raman N(2) return signals under cloud-free conditions. The lidar-derived aerosol backscattering ratio and an estimate of the aerosol extinction-to-backscatter ratio were used to compute the aerosol transmission. With a model reference temperature at 25 km, temperature profiles with a root-mean-square difference between the lidar and radiosonde temperatures of <2 K were obtained over an altitude range of 5-10 km for a 10-min integrated measurement with 300-m resolution.

Combination therapy with stavudine and didanosine in children with advanced human immunodeficiency virus infection: pharmacokinetic properties, safety, and immunologic and virologic effects

OBJECTIVES

To obtain preliminary information on the pharmacokinetic properties, tolerance, safety, and antiviral activity of combination therapy with stavudine and didanosine in children with advanced human immunodeficiency virus (HIV) infection.

METHODS

Eight children (median age, 6.6 years; range, 2.8 to 12 years) with advanced HIV disease (median CD4 + lymphocyte count at baseline, 42 cells/ microL; range, 8 to 553 cells/microL) were treated with stavudine (2 mg/kg per day in two divided doses) and didanosine (180 mg/m2 per day in two divided doses) for 24 weeks. Seven children had histories of prior zidovudine therapy. All children had received stavudine alone for 19 to 33 months before the addition of didanosine to the treatment regimen. Children were assessed clinically and with laboratory studies at baseline, weekly through week 4 of combination therapy, and every 4 weeks thereafter.

RESULTS

Analysis of stavudine and didanosine plasma half-life values, clearances, and area under the plasma concentration-versus-time curves revealed no obvious clinical pharmacokinetic interaction between the drugs through study week 12. Combination therapy was well tolerated, and there were no drug-associated clinical or laboratory adverse events. Signs and symptoms of peripheral neuropathy were not observed. All three children with baseline CD4 + lymphocyte counts greater than 50 cells/muL had greater than 20% increases in their counts within the first 12 weeks of therapy; CD4 + lymphocyte count increases were not observed in the other children. Plasma HIV RNA concentrations showed median declines of 0.88 log10 (range, -3.41 log10 to 0.31 log10) and 0.30 log10 (range, -0.63 log10 to 0.89 log10) at study weeks 12 and 24, respectively.

CONCLUSIONS

Combination therapy with stavudine and didanosine was well tolerated and safe in this small group of children with advanced HIV disease. Plasma HIV RNA concentration declines suggest a favorable effect of therapy on virus load. These findings should be confirmed, and the regimen's clinical efficacy should be examined, in controlled studies of HIV-infected children with less-advanced disease.

Providing better access to health care: a pediatric nurse practitioner WIC-based clinic for one-stop health care

The University of Texas Women, Infants, and Children (WIC) Well Child Clinic was established in January 1992 to provide high-quality "user-friendly" health care to children in Houston, Texas. As the name implies, the traditional services of the WIC nutritional program are coupled with primary care to offer more comprehensive and greater access to care. The services are provided by pediatric nurse practitioners and focus on health maintenance, with an emphasis on anticipatory guidance and immunizations. Acute care and management of chronic illness are also provided. The clinic serves as a teaching site for pediatric nurse practitioner and medical students. This article addresses the rationale for and planning of a WIC-based clinic and the implementation of the plan and addresses issues concerning reproducibility in other settings.

Identification of Mycobacterium tuberculosis and Mycobacterium avium-M. intracellulare directly from primary BACTEC cultures by using acridinium-ester-labeled DNA probes

Identification of members of the Mycobacterium tuberculosis complex and the M. avium-M. intracellulare complex (MAC) directly from primary BACTEC cultures was evaluated by using acridinium-ester-labeled DNA probes (AccuProbe; GenProbe, Inc., San Diego, Calif.). In preliminary experiments, blood present in samples was found to interfere with the assay because of nonspecific chemiluminescence, which was measured in relative light units (RLUs). There was a direct relationship between the age of the culture and the number of nonspecific RLUs. A protocol using 1% sodium dodecyl sulfate-5 mM EDTA to treat BACTEC broth cultures which, with specimens containing blood, gave on the average a ninefold reduction in nonspecific chemiluminescence was developed. By using this treatment protocol, 120 specimens were tested directly from BACTEC broth cultures with an AccuProbe for the M. tuberculosis complex and/or the MAC. In order to establish the background of the specimen, the patient sample was assayed without probe. The criteria for the inclusion of BACTEC cultures in the evaluation were a growth index of greater than or equal to 100 and a positive smear for acid-fast bacilli directly from the BACTEC broth. For the 120 cultures tested, if a hybridization result of greater than or equal to 30,000 RLUs was considered positive, the sensitivities for detecting the M. tuberculosis complex and the MAC were 47 and 90%, respectively, with a specificity of 100% for both. However, if a ratio of the RLUs obtained with the MAC or the M. tuberculosis complex probe to those obtained with the specimen background of >/= 20 was considered positive, this gave 77% sensitivity and 100% specificity for BACTEC cultures containing M. tuberculosis complex isolates and 96% sensitivity and 100% specificity for those growing MAC isolates.

Acquired monosaccharide intolerance in infants

To determine the frequency with which acquired monosaccharide intolerance (AMI) occurs in infants less than 3 months of age, we performed a prospective descriptive study of infants admitted to the hospital for diarrhea. We searched for differences between the characteristics and causes of AMI in these infants and those of a cohort of similar-aged infants admitted with acute diarrhea (AD). Five hundred fifty-five infants less than 3 months of age admitted with diarrhea were enrolled. Nine percent of those infants had AMI, 40% had other forms of chronic diarrhea, and 51% had AD. The mean age at hospital admission was 32 days for the infants with AMI and 44 days for the infants with AD. The mean weight loss of AMI infants was 0.3 g/day since birth, and the mean weight gain was 14.3 g/day for AD infants. The mean dehydration by difference in weights at admission and 48 h postadmission was 5% for AMI and 3% for AD infants. Bacterial and viral causes of the diarrhea were similar. At admission to the hospital, infants in whom AMI subsequently developed were younger, more malnourished, had more prolonged diarrhea, and were more dehydrated than the AD infants. Malnutrition stands out as a significant antecedent factor that contributes to the development of AMI.

Effect of holding temperature on isolation of Neisseria gonorrhoeae

The effect of holding temperature on the recovery of Neisseria gonorrhoeae was studied. From 300 specimens tested, Thayer-Martin medium plates inoculated and incubated in the presence of CO2 at 35, 22, and 4 degrees C for 24 h before incubation at 35 degrees C yielded 100, 96, and 95% of all isolates ultimately recovered from 82 positive specimens. Although there was a decrease in the quantity of organisms recovered, initial incubation of specimens under refrigeration or at room temperature yielded greater than or equal to 95% of the positive specimens.

Evaluation of four anti-microbic susceptibility testing systems for gram-negative bacilli

A total of 200 clinical isolates were assayed by five anti-microbic susceptibility testing systems. Two frozen minimal inhibitory concentration (MIC) systems (MicroScan and Pasco), an automated MIC system (AMS, Vitek Systems), and the standard disk diffusion were compared with a reference broth dilution method. Organisms tested included 100 resistant clinical stock strains and 100 fresh random clinical isolates. Overall, there were 1,600 anti-microbic-organism combinations analyzed. The Pasco and MicroScan systems had no major discrepancies, the AMS system had seven, and the disk diffusion two. The number of very major discrepancies were as follows: AMS, 11; disk diffusion, 9; MicroScan, 5; Pasco, 2. Of the total 36 major or very major discrepancies in the study, 33% (12 of 36) were with an aminoglycoside and 44% (16 of 36) occurred with a second-generation cephalosporin, of which 10 of 16 were with cefamandole. Overall, there was a greater than 98.8% essential agreement with all systems compared with the reference method.