Fulminant neonatal septicemia due to Hemophilus parainfluenzae.

A woman with premature rupture of membranes and chorioamnionitis gave birth to a 0.73-kg infant at 28 weeks' gestation. The infant died of fulminant septicemia caused by Hemophilus parainfluenzae. This organism should be recognized as a potential cause of chorioamnionitis and neonatal septicemia.

Rapid diagnosis of actinomycosis by thin-needle aspiration biopsy.

Actinomycosis was diagnosed in three cases by the use of thin-needle aspiration biopsy technic. Aspiration was utilized for morphologic studies and collection of material for microbiologic isolation. The critical histologic features of sulfur granules remain intact with aspiration technic. Thin-needle aspiration biopsy is a safe, simple, and rapid technic employed in the diagnosis of neoplastic disease. The use of this technic in the diagnosis of actinomycosis is demonstrated in this report.

Histologic chorioamnionitis, microbial infection, and prematurity.

The purpose of this study was to relate histologic chorioamnionitis to the isolation of microorganisms from the freshly separated chorioamnion in women who had early preterm delivery (before 35 weeks' gestation) following spontaneous labor. Histologic chorioamnionitis was identified in 51 of 95 study subjects. It was more common in the second trimester (72%) than from 27-34 weeks' gestation (33%) (P less than .001). Culture specimens were obtained for aerobic and anaerobic bacteria, yeasts, mycoplasmas, and Chlamydia. Microorganisms were recovered from 38 subjects; all culture reports were negative in 36. A statistically significant association was demonstrated between histologic chorioamnionitis and positive culture results. If any microorganism was recovered, 68% of the subjects had histologic chorioamnionitis, versus 39% if all cultures were negative. Of cases of histologic chorioamnionitis in the third trimester, 92% were associated with positive cultures, compared with 54% in the second trimester. Our results suggest that histologic chorioamnionitis is not synonymous with infection, especially in the second trimester.

Microbial resistance surveillance techniques. Blood culture versus multiple body site monitoring.

The continuing problem of nosocomial bacterial infections has resulted in the development of new techniques to monitor their prevalence and detect the emergence of drug resistance. "Focused microbial surveillance," in which bacterial incidence and antimicrobial susceptibilities are assessed by specific hospital units, provides unique information in the evaluation of emerging outbreaks of resistant Gram-negative pathogens. Within a given unit, however, pooled microbiologic data may be misleading, since they reflect only the average of multiple susceptibilities and may represent either colonization or infection. Formerly, at the University of Iowa Hospitals and Clinics, bacterial surveillance within a particular unit had typically been performed using blood-sample analysis, which was viewed as an effective index of the activity of most classes of antimicrobial agents. However, specific body site surveillance (wounds, sputum, urine, and so forth) may offer advantages over blood-culture analysis with some forms of resistance (or types of bacteria), such as stably derepressed type-I beta-lactamase production, which seems to develop rather quickly. Site-specific surveillance may enable earlier detection of rapidly emerging resistant strains and the identification of virulent new serotypes or specific causes. Our data demonstrated that there is a greater probability of detecting resistant bacterial strains of Enterobacter colonizing and subsequently producing infections in the respiratory tract, urinary tract, or wound site. There was a time delay of almost 3 years between first observing resistant strains in sputum, urine, or pus and encountering them in an alarming incidence among blood cultures. Other studies confirm this particular phenomenon. In a survey of penicillin-resistant enterococci, the majority of clinical isolates were obtained from sites other than blood: seven from urine; five from wounds; two each from rectal swabs, ascitic fluid, and blood; and one each from a peritoneal catheter, Bartholin's cyst abscess, and pancreatic abscess. Effective techniques for selective surveillance should be both sensitive and cost effective. Current evidence suggests that site-specific monitoring (wounds, sputum, pleural effusions, urine, and feces) offers the advantages of more rapid identification of resistance trends prior to their appearance in the bloodstream cultures.

A review of traditional resistance surveillance methodologies and infection control.

The hospital affords an excellent environment for the proliferation of pathogenic bacteria and for the selection of antimicrobial-resistant strains. This article traces the evolution of microbiologic surveillance techniques and highlights some of the more effective means of infection control. Traditional surveillance methods relied on nationwide antimicrobial susceptibility data for practical information regarding the nature of infectious disease trends in order to guide the selection of appropriate empiric antibiotic therapy. The application of nationwide antibiograms to the local hospital setting may mask the local emergence of rapidly developing resistances, such as chromosomally mediated type-I beta-lactamase resistance, which has been associated with increased use of certain cephalosporins. "Focused surveillance" techniques yield improved detection of emerging localized resistances within specific hospital units. In addition to unit-specific surveillance, many hospitals are now observing the advantages of an infection site-specific monitoring program. Judicious use of newer antimicrobials and implementation of detailed hospitalwide surveillance procedures will help to minimize the spread of epidemic and resistant infections. It remains the responsibility of the infection control and antibiotic utilization or advisory committees to make appropriate recommendations concerning the selection, restriction, and proper use of the newer extended-spectrum antibiotics. The clinical microbiology laboratory as a source of information remains a key participant in a quality program.

Improved urine screening using a combination of leukocyte esterase and the Lumac system.

Three rapid urine screening tests, leukocyte esterase, nitrite, and the Lumac System for detection of bacterial ATP, were evaluated alone and in combination to determine their utility in screening urine specimens from male patients for bacteruria. The combination of leukocyte esterase and Lumac testing resulted in significant improvement in the sensitivity of urine screening over each test individually and the combination of leukocyte esterase and nitrite. The leukocyte esterase/Lumac combination detected 98% of those specimens with greater than or equal to 10(5) CFU/ml and had a negative predictive value of 99%. The results obtained from this type of testing can be used with confidence to minimize the number of urine specimens cultured and to provide rapid reporting of negative results.

Polymerase chain reaction typing of nonviable Mycobacterium tuberculosis isolates.

Repetitive element polymerase chain reaction (PCR) typing was applied to two Mycobacterium tuberculosis isolates for which both viable and nonviable cultures were available. DNA extracted from the nonviable cultures and from fresh subcultures of the viable cultures was amplified with primers directed against the insertion sequence IS6110 and the polymorphic GC-rich repetitive sequence. For both isolates, the nonviable cultures generated PCR-banding patterns identical to those generated by the fresh subcultures.

Stomatococcus mucilaginosus bacteremias. Typical case presentations, simplified diagnostic criteria, and a literature review.

Even though Stomatococcus mucilaginosus is considered indigenous oral-pharyngeal flora, cited literature and case reports indicate that it can be the cause of infectious conditions. Tested strains were isolated from blood, the oral region, and wound sources. The organism was routinely misidentified or not identified by conventional or commercial systems (Vitek, STAPH-Trac). Four antimicrobial diagnostic disks for example, bacitracin (0.04 units; Taxo A), furazolidone (100 micrograms), novobiocin (5 micrograms), and polymyxin B (300 units), were evaluated as possible addition to previously applied biochemical characteristics that differentiate between S. mucilaginosus, Micrococcus sp., and coagulase-negative staphylococci. Consistent antimicrobial susceptibility patterns among our isolates to the diagnostic disks produced applicable characteristics for discriminating S. mucilaginosus from similar microorganisms. However, therapeutic choices of antimicrobial agents should be guided by individual organism susceptibility test results because of variable, often resistant patterns to beta-lactams, aminoglycosides, macrolides, new fluoroquinolones, and sulfonamides.

Multicenter comparison of the high volume (10 ml) NR BACTEC PLUS system and the standard (5 ml) NR BACTEC system.

This multicenter study was designed to compare the new BACTEC PLUS system (nonradiometric), which utilizes an 8- to 10-ml blood inoculum in a resin-containing medium, to the standard BACTEC (nonradiometric) without resins and 5-ml blood inoculum. There were 12,341 compliant sets studied, yielding 1331 positives, with 1099 sets deemed clinically significant. Overall the BACTEC PLUS showed an enhanced recovery of 33% (p less than 0.001) over its standard counterpart, with significant yield increased in the staphylococci (p less than 0.001), streptococci (p less than 0.002), pseudomonads (p less than 0.002), Enterobacteriaceae (p less than 0.001), and other aerobic Gram negatives (p less than 0.02). The enhanced performance increased to 53% if the patient was receiving any antibiotics at the time the blood was cultured. In patients known to be free of antibiotics at the time of blood draw, there was still an increased yield of 18%. The new system detected positivity at least one reading sooner than twice as often as the converse, and confirmed septic episodes significantly more often (21% overall) (41% on antibiotics) (15% no antibiotics). The BACTEC PLUS has distinct advantages over its low blood volume, nonresin counterpart.

Accuracy of the Vitek system for antimicrobial susceptibility testing Enterobacteriaceae bloodstream infection isolates: use of "direct" inoculation from Bactec 9240 blood culture bottles.

A recent investigation indicates that rapid antimicrobial susceptibility tests (AST) can affect patient therapy leading to reductions in health-care costs for some patient populations. However, there is little information relative to the often performed direct inoculation of positive blood culture bottles into rapid AST systems. AST results of direct inoculated Vitek (bioMerieux Vitek, Hazelwood, MO, USA) GNS cards were compared to those inoculated per package insert recommendations and a reference broth microdilution test using 50 consecutive Enterobacteriaceae bloodstream infection isolates. Escherichia coli (44% of isolates), Klebsiella ssp. (30%), and six other members of this family were tested against 15 antimicrobial agents. The direct inoculation method produced only two false-susceptible (0.3%), seven false-resistant (0.9%; six different drugs), and 48 minor errors (6.4%). The GNS cards inoculated in the usual, recommended manner had no very major error, and 7.5% combined major and minor errors. If the results of the urinary infection-specific drugs (nitrofurantoin, trimethoprim/sulfamethoxazole; not appropriate for bacteremia therapy) and ampicillin/sulbactam were deleted, both Vitek inoculation methods yielded results well within acceptable limits (< or = 4.5% overall error). These results indicate that the direct inoculation method of Vitek GNS cards from Enterobacteriaceae bloodstream infections (detected by Bactec 9240, Becton-Dickinson, Cockeysville, MD, USA) performed as well as the NCCLS broth microdilution test. Thus, a procedural modification of this type could further accelerate rapid access to accurate AST data.

Etest for routine clinical antimicrobial susceptibility testing of rapid-growing mycobacteria isolates.

The Etest has become a widely accepted alternative susceptibility-testing method for difficult-to-assess organisms, including rapid-growing Mycobacterium spp. Following an internal validation and literature reviews, the Etest was applied as the routine method for testing Mycobacterium chelonae and Mycobacterium fortuitum isolates. Results from testing 31 strains confirmed the utility of the Etest and the simplicity of the procedure. Mycobacterium chelonae were generally more resistant to all drugs except amikacin (MIC90, 32 micrograms/ml), compared with M. fortuitum strains that were inhibited (MIC50 in the susceptible range) by amikacin (1 microgram/ml), ciprofloxacin (0.032 microgram/ml), doxycycline (0.125 microgram/ml), and trimethoprim-sulfamethoxazole (0.032 microgram/ml). The polymyxin-B disk used as an identification method was confirmed (> or = 10 mm = M. fortuitum). The Etest provides a simple and accurate method for selecting appropriate therapy for infections caused by rapid-growing mycobacteria (a typical case report is presented).

CI-960 (PD127391 or AM-1091), sparfloxacin, WIN 57273, and isepamicin activity against clinical isolates of Mycobacterium avium-intracellularae complex, M. chelonae, and M. fortuitum.

A 7H9 broth microdilution method against CI-960, sparfloxacin, WIN57273, ciprofloxacin, norfloxacin, isepamicin, amikacin, kanamycin, ethambutol, isoniazid, and rifampin was used to test 35 Mycobacterium avium-intracellulare complex (MAI) and five M. chelonae-fortuitum strains. The majority of MAI isolates were inhibited by all tested compounds, with sparfloxacin (MIC90, 0.5 micrograms/ml) being the most active among the fluoroquinolones; isepamicin (MIC90, 4 micrograms/ml), the most potent aminoglycoside; and isoniazid, rifampin, and ethambutol also demonstrating some degree of activity. Mycobacterium chelonae strains were resistant to all drugs except ciprofloxacin (MIC50, 1 microgram/ml). Mycobacterium fortuitum isolates were generally susceptible, especially to the newer fluoroquinolones.

Colony morphology of Candida spp. as a guide to species identification.

The presence of colony projections, often referred to as "feet," have typically been considered a characteristic of Candida albicans. In the current study that examined the colony morphology of numerous different species of Candida, several clinical isolates of Candida tropicalis and Candida krusei were also noted to produce "feet." The medium and growth conditions under which colony projections were produced by these species were characterized.

Cefdinir (FK482), an orally administered cephalosporin in vitro activity comparison against recent clinical isolates from five medical centers and determination of MIC quality control guidelines.

Cefdinir, a new oral cephalosporin, was compared to cefaclor, cefadroxil, cefixime, and cefuroxime against greater than 5000 recent aerobic clinical isolates. This multicenter study revealed broad-spectrum cefdinir activity against all Enterobacteriaceae (MIC50s, 0.06-2 micrograms/ml) except Enterobacter cloacae, Morganella morganii, Proteus vulgaris, and Serratia marcescens (MIC50s, greater than or equal to 4 micrograms/ml). Oxacillin-susceptible staphylococci (MIC90s, 0.5-2 micrograms/ml), beta-hemolytic Streptococcus group B (MIC90, 0.06 micrograms/ml), and Acinetobacter lwoffii were also susceptible to cefdinir. The activity of cefdinir was similar to that of cefixime and cefuroxime against Gram-negative organisms and superior to all tested oral cephems when tested against Gram-positive cocci. None of the cephalosporins were active against oxacillin-resistant Staphylococcus spp., enterococci, Pseudomonas spp., or Xanthomonas maltophilia. MIC quality control range guidelines were established for the strains recommended by the National Committee for Clinical Laboratory Standards documents.

Cefmetazole and trospectomycin in vitro susceptibility testing interpretive criteria and quality control guidelines for Neisseria gonorrheae.

Cefmetazole and trospectomycin were tested in a multilaboratory trial to establish Neisseria gonorrhoeae susceptibility testing criteria and quality control (QC) guidelines. Cefmetazole was active against the penicillinase-producing isolates and has an MIC90 of 16 micrograms/ml, the breakpoint MIC previously used for nonfastidious species. However, a single-dose gonorrhea regimen (1 g i.m.) would require a lower less than or equal to 2 micrograms/ml breakpoint with a correlate zone (greater than or equal to 33 mm) consistent with similarly used cephamycins (cefoxitin and cefotetan). An intermediate category was proposed for MICs greater than 2-4 micrograms/m (28-32 mm) pending more clinical experience with higher and/or prolonged cefmetazole dosing regimens. Trospectomycin was active (MIC90, 8 micrograms/ml) against all spectinomycin-susceptible gonococci. A susceptible breakpoint MIC of less than or equal to 16 micrograms trospectomycin per milliliter was proposed with a correlate zone diameter of greater than or equal to 17 mm. An intermediate category was also suggested for trospectomycin at 32 micrograms/ml (14-16 mm). QC guidelines were established for 30-micrograms cefmetazole and 30-micrograms trospectomycin disk diffusion tests and the GC agar base MICs using a multilaboratory study design consistent with National Committee for Clinical Laboratory Standards (NCCLS) M23-T guidelines. Both drugs were stable in GC agar plates for 21 days stored at 2 degrees-5 degrees C.

Vitek GPS card susceptibility testing accuracy using direct inoculation from BACTEC 9240 blood culture bottles.

The emergent need for antimicrobial susceptibility testing (AST) data for the therapy of bacteremic patients has led to the development of rapid methods and local procedure modification of some commercial AST products such as the direct inoculation from blood culture systems. We compared the Vitek GPS card results using direct and standardized inoculation with a reference broth microdilution method for 112 consecutive staphylococcal bloodstream infections (seven drugs). Among the 28 Staphylococcus aureus strains, 0%-3.6% total error/drug was observed with both Vitek inoculation procedures. However, the only oxacillin-resistant strain was not detected (100% true very-major error). For 84 coagulase-negative staphylococci (CNS), the direct inoculation procedure had an 11.9% very-major error rate for oxacillin, ampicillin-sulbactam, and cephalothin, plus 4.8% very-major error rate for ciprofloxacin and trimethoprim-sulfamethoxazole (total error rate 4.8%-16.7% for five of seven drugs compared). The Vitek direct inoculation procedure routinely missed 20.4% of oxacillin-resistant CNS strains. The use of Vitek direct inoculation procedures for staphylococcal bloodstream infection isolates (from BACTEC 9240 cultures) produced serious false-susceptible results; this procedure should be avoided in favor of routine package insert-recommended Vitek procedures or other reference-quality overnight incubation susceptibility tests.

Development of Neisseria gonorrhoeae in vitro susceptibility test methods for cefixime including quality control guidelines.

Cefixime was tested in a multilaboratory study to establish susceptibility testing interpretive criteria and quality control (QC) guidelines for Neisseria gonorrhoeae. Interpretive criteria were established by using triplicate testing of 102 representative gonococcal strains. Only a susceptible category was proposed for cefixime (greater than or equal to 31 mm and less than or equal to 0.25 micrograms/ml) because of very rare, resistant isolates. QC ranges [N. gonorrhoeae American Type Culture Collection (ATCC) 49226] were established using multiple GC agar lots, three disk lots, and a number of test replicates consistent with the National Committee for Clinical Laboratory Standards (NCCLS) M23-T guidelines. Cefixime was stable in GC agar medium for at least 21 days when stored at 2 degrees-5 degrees C. Oral third-generation cephalosporins, such as cefixime, appear to represent potentially useful clinical alternatives to parenteral drugs of the same class for single-dose therapy of gonorrhea.

Interpretive criteria and quality control guidelines for lomefloxacin and meropenem in susceptibility tests of Haemophilus influenzae using Haemophilus test medium.

Lomefloxacin and meropenem were tested in a multilaboratory study to establish susceptibility testing interpretive criteria and quality control (QC) guidelines for Haemophilus influenzae using Haemophilus test medium (HTM). Interpretive criteria were established by using triplicate testing of 102 representative H. influenzae strains. Only a susceptible category was proposed for lomefloxacin (greater than or equal to 22 mm and less than or equal to 2 micrograms/ml) and meropenem (greater than or equal to 13 mm and less than or equal to 4 micrograms/ml) due to the lack of resistant isolates. QC range for H. Influenzae ATCC 49247 were established using multiple HTM agar and broth base lots, three disk lots for each drug, and a number of test replicates consistent with the National Committee for Clinical Laboratory Standards M23-T guideline.

Comparison of identification systems for Staphylococcus epidermidis and other coagulase-negative Staphylococcus species.

Three commercially available systems (API Staph-Trac, API 20GP, and Vitek GPI), used to identify coagulase-negative staphylococci, were evaluated against 277 bloodstream isolates, including 94 isolates of Staphylococcus epidermidis and 183 isolates of other coagulase-negative Staphylococcus species. The conventional method of Kloos and Schleifer served as the reference method. Controls included 14 ATCC type culture strains of coagulase-negative staphylococci. The API Staph-Trac system showed the highest rate of agreement with reference method, correctly identifying 73% of the isolates. The Vitek GPI System had an overall rate of agreement of 67% and the API 20GP system correctly identified 61%. The API Staph-Trac system correctly identified 94% of the isolates of S. epidermidis compared with 64% by both Vitek GPI and API 20GP. The most common error for both Vitek GPI and API 20GP systems was the failure to identify organisms contained within the database of the systems. Because none of the tested commercial identification systems identified "non-epidermidis" coagulase-negative Staphylococcus species with a high degree of accuracy, the systems need to be markedly improved or new systems developed.

Trends in post-operative infections by Gram-positive bacteria.

Surgical patients are now more prone than ever to have a post-operative infection. On average, they are now older and more have chronic disease histories with reduced immunocompetence or iatrogenic immunosuppression, and many undergo more aggressive, more complex surgical procedures. Moreover, the infectious agents have changed. A comparison of data collected by the SENTRY Antimicrobial Surveillance Program for the years 1988 and 1998 from North and Latin America and Europe shows important shifts in the nature of the infectious agents. Among the Gram-positive agents, Staphylococcus aureus was the most frequent isolate in both years, but its share has more than doubled. Beta-hemolytic streptococci increased their share from 3 to 5% while enterococci fell from 13 to 8%. Perhaps more important than the shifts in incidence are dramatic changes in the antimicrobial resistance patterns of these agents. Data from the past several years show increasing resistance for the drugs that were previously considered 'first line' treatment for post-surgical infections. The majority of S. aureus and coagulase-negative staphylococci are now resistant to most classes of antibiotics. Antimicrobial resistance is beginning to be detected in beta-hemolytic streptococci, and vancomycin-resistant enterococci, which were not even reported in 1987-1988, now represent 17% of all enterococci isolated in the USA and Canada. To stay ahead in the fight against surgical infections, we must react in a combination of ways, using disinfection, prophylaxis, new antibiotics and, above all, we must practice superb hospital infection control and world-wide antimicrobial epidemiology studies.