Ciprofloxacin versus tobramycin plus azlocillin in pulmonary exacerbations in adult patients with cystic fibrosis.

Twenty adult patients with cystic fibrosis who were experiencing acute pulmonary exacerbations were enrolled in a randomized, controlled trial comparing oral ciprofloxacin with intravenous tobramycin plus azlocillin. Efficacy of the two treatments was compared based upon changes in clinical status, pulmonary function tests, white blood cell counts, and quantitative bacteriology of sputum. No statistically significant differences were detected in these parameters of response between the two treatment groups (p greater than 0.05). Ciprofloxacin appears to be therapeutically equivalent to intravenous antibiotics in the treatment of adult patients with cystic fibrosis who are experiencing pulmonary exacerbations associated with susceptible bacteria.

Specimen collection and transport.

The approach to the collection and transport of meaningful and accurate microbiologic specimens depends upon the nature of the suspected infectious entity and upon the location of the pathogenic process, as well as the possession of appropriate instrumentation and containers. New information and newly developed collection-transport materials have improved the potential for the successful collection and isolation of pathogenic micro-organisms.

In vitro effects of lidocaine on anaerobic respiratory pathogens and strains of Hemophilus influenzae.

Lidocaine is commonly employed as a topical anesthetic agent during fiberoptic bronchoscopic procedures or transbronchial brushing. Previous studies have demonstrated an inhibitory effect of lidocaine on the growth in culture media of gram-positive and gram-negative organisms, as well as several species of Mycobacterium and various fungi. The current in vitro investigation demonstrates an inhibitory, as well as a bactericidal, effect of lidocaine hydrochloride (in concentrations identical to those encountered during fiberoptic bronchoscopic procedures) on the common anaerobic respiratory pathogens and on multiple strains of Hemophilus influenzae. The finding helps to explaint the difficulty in producing proof via culture of the specific etiologic agent in inflammatory lesions from specimens obtained by fiberoptic bronchoscopic procedures or transbronchial brushing.

The use of aztreonam in the cystic fibrosis patient.

Eradication of pulmonary infection by Pseudomonas aeruginosa in cystic fibrosis (CF) patients has long presented a significant challenge to the medical community. Many antimicrobial agents have proved incompletely effective against this persistent pathogen, and even the aminoglycosides, which represent the traditional therapy for such infections, have been associated with considerable toxicity and resistance. The monobactam antibacterial agent aztreonam is used both as single-agent therapy and in combination with other drugs. Several controlled, clinical trials have demonstrated the efficacy of aztreonam in the treatment of CF patients with pulmonary exacerbations caused by P. aeruginosa. The only side effect of aztreonam therapy commonly encountered in these studies was elevation of hepatic transaminase concentrations; this effect was of uncertain significance. It was concluded that aztreonam may offer clinical efficacy comparable to that provided by the combination of tobramycin plus azlocillin. Further, there does not seem to be any appreciable difference in the development of resistance to aztreonam compared with traditional therapies.

Efficacy of aztreonam in pulmonary exacerbations of cystic fibrosis.

A noncomparative pilot study was conducted to assess the potential usefulness of aztreonam in pulmonary exacerbations of cystic fibrosis. Of 27 patients initially enrolled 25 received sufficient courses of aztreonam therapy to be evaluable. All patients received 200 mg/kg/day of aztreonam in 4 equally divided doses administered intravenously. Of 57 isolates of Pseudomonas aeruginosa from pretherapy sputum cultures, 48 were susceptible to aztreonam in vitro as were 11 of 18 strains isolated at the conclusion of therapy. With treatment colony counts of P. aeruginosa in sputum were reduced by 3 log10 or more in 15 patients. It was totally (but temporarily) eradicated in 11 of these patients. Clinical scores and white blood cell counts improved significantly (P less than 0.05). Side effects of aztreonam were limited to transient elevations of liver enzymes occurring in 16 patients. Aztreonam merits further evaluation in a randomized, comparative trial with standard antibiotic therapy for cystic fibrosis.

In-vitro inactivation of aminoglycoside antibiotics by piperacillin and carbenicillin.

Clinical microbiology laboratory experiences wherein aminoglycoside serum assay results appeared inconsistent with the amount of the compound given when administered in combination with a semisynthetic penicillin led us to compare the interaction of three currently available aminoglycoside antibiotics with carbenicillin, as a representative semisynthetic penicillin given in large doses, and with piperacillin, a new broad-spectrum semisynthetic penicillin. Amikacin, gentamicin, and tobramycin were incubated in serum in vitro with various concentrations of carbenicillin and piperacillin. In the presence of very high concentrations of the two penicillins, tobramycin was the most rapidly inactivated aminoglycoside, gentamicin was next, and amikacin was only slightly inactivated. With low concentrations of the two penicillins, the rates of aminoglycoside inactivation were negligible. Carbenicillin, in high concentration, inactivated the aminoglycosides more rapidly than piperacillin. In patients experiencing renal failure, the maintenance of moderate serum levels of carbenicillin and piperacillin may be important in attempting to maintain adequate aminoglycoside serum levels.

Comparison of visual and photometric Bac-T-Screen results.

The Bac-T-Screen (Marion Laboratories, Kansas City, MO) was used to screen 826 urine specimens. Of these, 85 either pigmented or clogged the Bac-T-Screen filter and could not be evaluated. Results for the remaining 741 specimens were examined both visually and photometrically by a newly developed photometric card reader. The results were then compared. Screening results for all urines containing greater than or equal to 10(5) pathogens/mL were equivalent for both methods, with sensitivity and predictive negative values of greater than 98% and greater than 99%, respectively. The predictive values of positive tests were also equivalent at 57.5% for visual and 59.6% by photometry. The overall agreement varied with the card reader value used because the photometric card-reader procedure allows the user to select desired sensitivity and specificity levels.

An evaluation of the practicality of the spot-indole test for the identification of Escherichia coli in the clinical microbiology laboratory.

Colony morphology and the spot-indole test were evaluated to assess the practicality of the rapid identification of Escherichia coli isolates directly from primary isolation plates. One hundred ninety-one lactose-fermenting, gram-negative bacilli were identified by standard testing procedures (either API-20E, Micro-ID, or a 5-test biochemical battery). These isolates also were tested with the spot-indole test, using either a 1% or 5% p-dimethylaminobenzaldehyde or 1% p-dimethylaminocinnamaldehyde reagent. Of the total 191 E. coli isolated, 128 (67.0%) were single-colony types on the primary plates, and 112 (58.6%) met the morphologic criteria and were positive and spot-indole testing. Of these 112, 111 (99.1%) were identified accurately as E. coli by the morphologic criteria/spot-indole approach. This method can be recommended as a practical diagnostic aid in the clinical microbiology laboratory as it allows significant cost and time savings for the majority of the most frequently isolated gram-negative bacilli.

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.

The spot indole test for identification of swarming Proteus.

The authors evaluated the use of the spot indole test for rapid speciation of swarming Proteus from the primary isolation plate. One hundred seventy-two consecutive isolates of swarming Proteus were studied, 163 Proteus mirabilis and nine Proteus vulgaris. One hundred fifty-six isolates (95.7%) of Proteus mirabilis gave a negative spot indole. Seven (4.3%) gave a positive spot indole test, but all seven isolates were from cultures in which other indole-producing organisms also were present. If only isolates representing single gram-negative strains in the specimens were tested, the predictive value was greater than 99%. Eight of the nine (88.9%) Proteus vulgaris isolates gave a positive spot indole test; one (11.1%) gave a negative result. This isolate also failed to produce indole by conventional methods but was ornithine decarboxylase negative, and additional biochemical testing was consistent with the Proteus vulgaris identification. All Proteus vulgaris isolates were resistant to ampicillin, and 94.2% of the Proteus mirabilis tested were ampicillin susceptible. The spot indole test is a rapid, accurate, simple, and cost-effective means of speciating swarming Proteus strains isolated as the only gram-negative bacilli in a specimen. The spot indole test should be used in conjunction with an ampicillin susceptibility test result or other confirmatory test information if other gram-negative bacilli are present in the culture.

Laboratory evaluation of urinary tract infections in an ambulatory clinic.

A 4-month evaluation of ambulatory patients with a suspicion of a urinary tract infection was performed. Specific objectives included assessment of five urinary screening methods, reevaluation of the necessity of the phenylethyl alcohol plate (PEA), and cost-effectiveness of screening for low colony count bacteriuria. Urine samples were collected as midstream, clean-caught specimens. A total of 142 samples, 87 from 79 symptomatic patients and 55 negative controls, were evaluated. All urine specimens were cultured using a 0.01 mL loop and a 0.001 mL loop onto Columbia sheep blood agar, MacConkey agar, and PEA agar. Twenty-four specimens (17%) were sterile, 64 (45%) were contaminated, and 54 (38%) were infected. Five urine screening methods were performed. These tests and their associated sensitivity and specificity are as follows. The Chemstrip 9 (Behring, Inc., Somerville, NJ) for leukocyte esterase and nitrate, 67%, 98%; microscopic analysis on spun urine, 79%, 93%; methylene blue stain for pyuria, 60%, 99%; Gram stain for pyuria, 45%, 93%; Gram stain for bacteriuria, 65%, 75%; and the URISCREEN (Analytab Products, Plainview, NY), 92%, 89%. Inclusion of a PEA plate for isolation of gram-positive organisms provided no additional information. Routine culture of urine samples at 10(-2) mL increased the contamination rate by 19%.

Means to facilitate physician acceptance and use of rapid test results.

Rapid testing methods can have a positive impact on patient care and help ease the mounting economical pressures facing clinical microbiology laboratories. Rapid test reporting, the validation of rapid test procedures and results, and physician acceptance and use of these tests are among the 10 categorical measures outlined to help laboratories optimize productivity, efficiency, and economic and patient-care impact.

In vitro activity in deptomycin (LY-146032) compared with other antimicrobial agents against gram-positive cocci.

A comparison was made of the activity of deptomycin (LY-146032) with that of ampicillin, cephalexin, cefamandole, cephalothin, erythromycin, teicoplanin, tetracycline, and vancomycin. The minimal inhibitory concentration (MICs) for greater than or equal to 90% of 356 Gram-positive cocci, against deptomycin, were less than or equal to 2 micrograms/ml. The MICs for the other antimicrobials varied greatly depending on the compound. A slight and unexplained inoculum effect was observed for LY-146032.

Comparative in vitro activity of lomefloxacin (SC 47111 or NY-198) against fresh clinical bacterial isolates.

The in vitro antibacterial activity of a new difluorinated quinolone (lomefloxacin) was compared with that of ten selected antibiotics against 744 fresh bacterial isolates representing 32 species. Lomefloxacin was comparable to other quinolones tested against Enterobacteriaceae (MIC90, less than or equal to 0.25 micrograms/ml) and generally more effective than other compounds tested against Staphylococcus spp. and Pseudomonas aeruginosa with MIC90s of less than or equal to 2 and less than or equal to 4 micrograms/ml, respectively.

Evaluation of a rapid bacteriuria screening instrument.

A newly modified, semiautomated instrument (Bacteriuria detection device (BDD] designed to detect the presence of bacteriuria in less than 3 min was compared to quantitative urine culture plating techniques. The instrument consists of a self-enclosed vacuum-filtration-staining system in which a 1-ml urine filtrate is stained on a filter. The resulting color determines the quantitation. Of the total of 525 clinical urine specimens tested, 66 (12.6%) were uninterpretable due to pigment deposition or inability to complete the filtering process (clogging of the filter). Of the remaining 459 specimens, 93 (20.3%) had a plate quantitation colony count of 10(5) colony-forming units (CFU)/ml or more. The BDD detected 94.2% of these positive specimens if only significant pathogens were included (85% if specimens that were probably contaminated were also included). For specimens containing significant pathogens at 10(4)-10(5) CFU/ml, the BDD detection rate was 41%. The device detected most (94.3%) gram-negative bacilli and enterococci at colony counts of 10(5) CFU/ml or more. In addition, the BDD accurately detected 95.6% of specimens with no growth or fewer than 10(4) CFU/ml. With several proposed modifications, these results suggest that this instrument is potentially useful as a urine screening device in a select population.

Absence of rapidly developing resistance during treatment of cystic fibrosis patients with aztreonam.

The in vitro activity of aztreonam and 10 other antibiotics was determined for clinical isolates of Pseudomonas aeruginosa from 18 cystic fibrosis patients obtained before, at the end of, and 7-14 days after the completion of therapy with aztreonam. The percent of isolates susceptible to aztreonam at each sampling period were 79%, 78%, and 81% respectively.

Use of and cost savings with morphologic criteria and the spot indole test as a routine means of identification of Escherichia coli.

The use of primary isolation plate colonial morphologic criteria (CMC) of a flat, nonmucoid, lactose-fermenting, gram-negative rod on MacConkey agar and the spot indole (SI) test from the sheep blood agar plate was evaluated as a means for identification of Escherichia coli in comparison to kit (Micro-ID, API-20E) and conventional biochemical testing. In this preliminary phase of comparison of accuracy, 427 isolates of E. coli (69.8%) from a total of 612 isolates of lactose-fermenting gram-negative rods were evaluated. Of these E. coli isolates, 357 (83.6%) fit the CMC and were SI positive; 3 (less than 1% error rate) were not E. coli. In the second phase of the evaluation, using CMC and SI alone as a means for identification of E. coli, 472 (57.6%) E. coli isolates from a total of 820 Enterobacteriaceae isolates were assessed. Of these E. coli isolates, 326 could be identified using only CMC and SI (69.1% of the E. coli isolates and 39.8% of all Enterobacteriaceae isolates); 146 (30.9%) required additional biochemical testing because of atypical colonial morphology, because of the investigator's inability to differentiate colony types on both media or lack of isolated colonies on either of the two required media, or because as isolates from sterile body sites they were processed directly to Micro-ID kits. A minimum of 40% savings on Enterobacteriaceae identification schemes without compromising accuracy was calculated. As of November 1983, a direct (labor and materials) cost savings of approximately +200.80 per 100 Enterobacteriaceae identifications was projected.

Bactericidal activity of cefoperazone in comparison with other beta-lactam antibiotics and gentamicin.

Killing curves were employed to determine the in vitro bactericidal activity of cefoperazone against several aerobic bacterial species of clinical origin. Cefoperazone was bactericidal at concentrations equal to, or greater than, the minimal inhibitory concentration (MIC) but allowed regrowth of the organisms after four to six hours when tested in concentrations of one-fourth or one-half the MIC. Comparative studies with gentamicin, LY127935 (moxalactam), piperacillin, cefamandole, and cephalothin indicate that, in general, cefoperazone demonstrated similar killing activity as other beta-lactam compounds, with some strain differences noted. Gentamicin, as the representative aminoglycoside, demonstrated a greater rate of bactericidal activity than the beta-lactam compounds studied.

Packaged commercial bacterial identification systems.

The authors attempt to provide a useful and current guide for clinical microbiologists who are seeking a review of the available packaged commercial systems for bacterial identification. Each system is outlined according to test principle, laboratory procedures, turn-around time, and limitations. Selected peer evaluations and references for many of the systems are also cited.

The regionalization of laboratory services at the University of Utah Medical Center. Associated Regional and University Pathologists Inc (ARUP).

We feel that now, four years out, we have achieved the interim goals that we set for ourselves. There are some key aspects that we would do differently if we were now starting over, and we have provided that information to those seeking to begin similar off-site ventures who have sought our advice. There is an interesting constellation of factors that must be present for such an operation to succeed, and the individual components of that constellation will differ by institution and location. The rationale and circumstance will vary profoundly, and what is "right" in one setting may be entirely "wrong" in another. I feel compelled to caution the reader about the myriad of determinants and ingredients that must be considered. Study the precedents and seek knowledgeable advice from financial, legal, insurance, human resource (personnel), and laboratory management professionals. Regional laboratories can succeed. Hospitals may well benefit from a strategy of marketing services to physician staff members and the incremental financial and service benefits from added testing volume can be significant. However, the more expansive the business design, the more complicated the management requirements and demands and, potentially, the higher the risks, costs, pressures, and down-side factors. We feel very strongly about our focus of supporting the pathology and medical technology professions. Our value-added services are geared not only to providing technology, management, and financial services support for our clients, but also to not competing with them for local clientele. We have a program of teaching them how to market to that clientele and of providing the support materials to assist them in so doing. We have progressed from being a hospital laboratory to being a hospital laboratory referral laboratory, and now have also become a referral laboratory for other reference laboratories. As a full-service reference laboratory we send out very few tests, and are continually incorporating new tests and technologies. We have referral testing accounts currently in 42 states and we want to be the very best at what we do, namely, esoteric reference testing. Our credo is that quality at ARUP is making best continually better.