Reemergence of epidemic methicillin-resistant Staphylococcus aureus in a general hospital associated with changing staphylococcal strains.

An epidemic of methicillin-resistant Staphylococcus aureus (MRSA) infections involving 323 patients occurred at the University of Cincinnati Hospital from 1977 to 1981. Subsequently, endemic MRSA persisted in the hospital for 6 years, until 1987, when a new epidemic began with 223 patients becoming infected over 3 years. Between the two epidemics, there was a major change in the MRSA recovered from infected patients, as demonstrated by three epidemiologic markers. Antibiograms showed that the tetracycline-resistant MRSA involved in the first epidemic was replaced by tetracycline-susceptible MRSA in the second epidemic; bacteriophage typing indicated that the original epidemic strain, D11/83A/85, had been replaced by new strains, many of which were susceptible to phage 54; and restriction endonuclease analysis of plasmid DNA confirmed that a single strain was involved in the first epidemic and that multiple strains were present in the second epidemic. The epidemiology of MRSA infections in the hospital changed with the change in staphylococcal strains. The first epidemic was hospital based with most infections occurring in surgical patients, and the burn unit was the major reservoir. In contrast, 28% of the patients in the second epidemic had community-acquired infections, and nursing home patients were an important source of these infections. Also, 29% of the hospital-acquired infections in this epidemic occurred in nonsurgical patients. This time the burn unit was not a reservoir of infection, but other intensive care units were. The increased diversity of strains of MRSA in the second epidemic might be related to increased transmission in the community and more widespread transmission in the hospital.

Neonatal necrotizing enterocolitis associated with penicillin-resistant, toxigenic Clostridium butyricum.

The cause of neonatal necrotizing enterocolitis (NEC) is unknown. An association between NEC and clostridial infection has been reported from several centers, but the organisms have not been extensively characterized. Clostridium butyricum was isolated from the peritoneal fluid and cerebrospinal fluid of a neonate with NEC. The organism was resistant to the penicillins, but sensitive to vancomycin. Toxin production was demonstrated. Although the role of clostridial toxins in the pathogenesis of NEC is unknown, clostridial toxins are well established as the causes of two other intestinal diseases (antibiotic-associated pseudomembranous colitis and pig-bel). Further investigation of the role of clostridia in the pathogenesis of NEC and of the use of oral, nonabsorbable antibiotics in the treatment of NEC is needed.

Pediatric Legionnaires' disease: diagnosis by direct immunofluorescent staining of sputum.

Legionnaires' disease occurred in a 3-year-old boy with Down's syndrome. His illness was characterized by bilateral pneumonia, high fever, and response to erythromycin. The diagnosis was made by demonstrating Legionella pneumophila, serogroup 1, in sputum with a direct fluorescent antibody stain. L pneumophila antigen was detected in urine by an enzyme-linked immunospecific assay. The diagnosis was confirmed by a more than fourfold rise in serum antibody titer. Although Legionnaires' disease appears to be uncommon in children, it should be included in the differential diagnosis of pneumonia in the immunocompromised child.

Control of methicillin-resistant Staphylococcus aureus in a neonatal intensive-care unit: use of intensive microbiologic surveillance and mupirocin.

OBJECTIVE: To describe the epidemiology and the interventions used to control two methicillin-resistant Staphylococcus aureus (MRSA) epidemics involving 46 infants with two fatalities in a neonatal intensive care unit (NICU). SETTING: A 50-bed, level III NICU in a university hospital. INTERVENTIONS: After traditional interventions failed to stop the first epidemic, an intensive microbiologic surveillance (IMS) program was developed. Cultures were obtained on all infants each week, and those colonized with MRSA were isolated. When an infant was found to be colonized with MRSA, cultures immediately were obtained on all surrounding infants. This was continued until no MRSA-colonized infants were found in the area. During the first epidemic, mupirocin was used in an attempt to eradicate the organism from the unit. RESULTS: All infants, colonized and noncolonized, and parents of and personnel working with colonized infants were treated simultaneously with 5 days of mupirocin. This failed to eradicate MRSA in colonized infants. The spread of MRSA ceased in the unit, but a second epidemic occurred 4 months later. This time, IMS alone was successful in quickly containing the epidemic, and MRSA disappeared from the unit after all colonized infants were discharged. Plasmid analysis demonstrated that the same strain was responsible for both outbreaks. CONCLUSIONS: IMS and isolation are effective in containing the spread of MRSA in an NICU. The use of mupirocin failed to eradicate the organism.

Infection of bone by Mycobacterium fortuitum masquerading as Nocardia asteroides.

A case of traumatic osteomyelitis of the leg yielded on culture a branching partially acid-fast organism that failed to respond to therapy directed at Nocardia asteroides. Subsequent laboratory investigation revealed the organism to be Mycobacterium fortuitum. N. asteroides and M. fortuitum can demonstrate similar staining and morphologic patterns microscopically, as well as common colonial and cultural characteristics. Separation can be aided by careful examination of the branching pattern, and can be established by thin-layer chromatography of lipid extracts of the organism. Correct identification of these species in the laboratory is important because of some overlap in their clinical syndromes and because of differences in their susceptibilities to antibiotics.

The pull-through procedure: technical factors in influencing outcome, with emphasis on pouchitis.

BACKGROUND: The purpose of the study was to review those features that we believed to be critical to the successful performance of the ileal pouch-anal anastomosis, or pull-through, procedure, and specifically the complication of pouchitis. METHODS: The charts of 205 patients who successfully underwent ileal pouch-anal anastomosis procedure were reviewed. No follow-up was available in five patients; therefore, the basis of this report and its analysis was based on 200 consecutive procedures in which at least two of the three surgeons participated. Particular emphasis was placed on continence, particularly nighttime continence. The incidence of pouchitis, either a single episode or intermittent episodes, was surveyed. Particular attention was paid to the level of rectal mucosectomy and anastomosis at the top of the columns of Morgagni, thus retaining the transitional zone. RESULTS: Only 5% of patients were incontinent in the absence of pouchitis. Twenty-five patients (13%) wore a pad at night, but only nine (5%) wore a pad during the day. Of those patients with pouchitis, 6% (12) have had a single episode and 12% (23) were intermittently on medication. Therapy of pouchitis was usually carried out with ciprofloxacin 500 mg by mouth everyday or twice a day. CONCLUSIONS: Ileal pouch-anal anastomosis is an excellent procedure, provided technical details are adhered to. Satisfactory outcome with respect to nighttime continence can be achieved with rectal mucosectomy with minimal manipulation and retaining the transitional epithelium, performing the pouch anastomosis at the top of the columns of Morgagni. The incidence of pouchitis is disappointing but need not be inhibiting of either patients or carrying out this life-saving procedure in patients with ulcerative colitis and familial polyposis.

Staphylococcus in toxic shock syndrome and other surgical infections. Development of new bacteriophages.

Recent studies of Staphylococcus aureus isolates from patients with toxic shock syndrome (TSS) have shown the dominance of phage type 29/52 with the capacity to produce pyrogenic exotoxin C and enterotoxin F. They also showed that 29% of the isolates were nontypable and 90% of them had similar toxigenic properties. The existence of unknown and important phages in this disease was postulated. Five new phages were then developed and used for typing three groups of staphylococcal isolates: 236 from patients with TSS, 67 from patients without TSS, and 159 from patients with infected burns. Results showed a high correlation between the lytic action of the new phages and the 29/52 phages, and an additional typing capability in 35% of the previously nontypable TSS isolates, emphasizing further the potential of bacteriophage typing of S aureus in these infections.

Impact of technological developments and organizational strategies on clinical laboratory cost reduction.

Health care reform efforts, largely under the aegis of managed health care initiatives, have prompted clinical laboratories to increase efficiency and reduce both expenditures and test turnaround times. The adoption of newer technologies is viewed as a mechanism of achieving the latter objectives, but direct and indirect costs and outcomes are often difficult to project. Issues explored in this article include the impact on a large university hospital-based clinical microbiology laboratory following the application of various technological approaches to organism recognition and susceptibility testing and the consolidation of certain testing services. Included are applications of an automated blood culture system; radiometric detection, identification, and susceptibility testing of mycobacteria; and the use of molecular probes to identify various microorganisms. Assessment was made through retrospective review of direct costs, estimates of average test report turnaround times, work flow changes, and real or perceived outcomes. Both the application of technology per se and consolidation of an independent virology service into the general microbiology laboratory enabled improvement in test report times and led to direct or indirect cost reduction. Managerial strategies to bring about organization changes throughout all clinical laboratories in response to a major hospital-wide cost reduction program are also presented together with financial outcomes achieved.

Screening tests and "rapid" identification. Is anybody out there listening?

The responses by 55 of 300 physicians queried at the University Hospital, Cincinnati, to an extensive questionnaire, form the basis for this comment on the clinical impact of screening tests and rapid identification. Examination and interpretation of smears of fluids and tissue were felt to provide useful data within a short time of specimen collection and the majority of physician respondents were willing to sacrifice some degree of accuracy in results in return for an answer delivered shortly after specimen submission. Screening for bacteriuria was felt to be useful if the test was sensitive enough to rule out infection as suggested by the presence of approximately 10,000 CFU/ml of urine, if results could be had within 1 hr of specimen collection for outpatients, 2 hr for inpatients, and if test results for pyuria accompanied the screen results. The value of taxonomy, in general, was directly related to how much knowing the taxon would direct antibiotic therapy. The time required for a taxonomic result seemed to matter only when susceptibility test results were either delayed or not forthcoming. Interest in the taxonomy of anaerobic bacteria appeared to be limited to a small group of physician respondents (infectious disease specialists) and also was relative to the ability of the taxonomic designation to evoke a specific therapeutic regimen. In summary, the impact of microbiologic data on the practice of medicine appears to depend on the ability of the laboratory to complete the entire test process, from order to transmission of answer, within a time frame perceived to be useful by the clinician.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioassay of teicoplanin in serum containing rifampin or a beta-lactam antibiotic.

The purpose of this study was to develop bioassays for the measurement of teicoplanin in serum containing rifampin or a beta-lactam antibiotic. Use of rifampin-resistant Bacillus subtilis as indicator organism or pretreatment of the serum sample with Bacillus cereus penicillinase Type I (nafcillin, ticarcillin, mezlocillin) or Type II (cefazolin, cefuroxime, ceftazidime, ceftriaxone) effectively eliminated assay interference. Validation bioassays performed on two separate days utilizing triplicate coded serum samples containing 0 to 200 micrograms teicoplanin in combination with 40 micrograms/ml rifampin or 200 to 500 micrograms/ml beta-lactam showed no significant differences (p greater than 0.05, two-way analysis of variance) in analyte recovery between assay days. Regression analysis of each teicoplanin/rifampin or teicoplanin/beta-lactam data set yielded slope values of 0.92 to 1.01, intercept values of -0.45 to 0.84 and correlation coefficients of 0.9925 to 0.9990. Thus, serum teicoplanin can be quantitated accurately, precisely, and reproducibly in patients receiving concomitant rifampin or beta-lactam chemotherapy.

Survival of Streptococcus pneumoniae in corneal storage media.

The Cincinnati Eye Bank had six corneoscleral rims in which Streptococcus pneumoniae was cultured after preservation in corneal storage media. To determine the survival of this organism under conditions common for corneal storage, gentamicin-supplemented McCarey-Kaufman (M-K) medium and chondroitin sulfate/Dextran medium (Dexsol, Ciron Ophthalmics, Irvine, CA, U.S.A.) were inoculated with S. pneumoniae and kept at 4 degrees C. Thioglycollate broth plus 10% rabbit serum (Thio-S) and tryptic soy broth (TSB) served as growth controls. At day 14 after inoculation of 10(5) colony-forming units (CFU)/ml, Dexsol showed a 1-log decrease in bacterial concentration, the M-K medium a 2-log decrease and Thio-S a 4-log decrease, whereas TSB showed no detectable organisms. By day 21 Dexsol had only a 2-log decrease in bacteria. These data suggest that corneal storage medium supplemented with gentamicin does not exert bactericidal activity against S. pneumoniae and may actually support its survival at 4 degrees C.

Cutaneous abscesses: natural history and management in an outpatient facility.

This study investigated the natural history and treatment of cutaneous abscesses in an outpatient setting. Incision, drainage, aerobic and anaerobic cultures were done on all 78 patients entered in the study. Tenderness and fluctuance were noted in more than 80% of the patients; erythema and induration in more than 60%. Forty-one percent of all abscesses were in the anogenital region. Forty-two percent of cultured abscesses grew aerobes exclusively, 28% grew anaerobes exclusively, and 27% grew a mixture of aerobes and anaerobes. The predominant aerobic organisms were Staphylococcus and Streptococcus, which were mostly isolated from the head/neck, extremities, and axillary regions. The predominant anaerobic organisms were Peptococcus and Bacteroides, which were primarily isolated from the anogenital regions. Nearly 60% of the patients returned for reevaluation. They were equally divided between those patients taking antibiotics and those not on antibiotics. However, all patients were clinically improved.

Microbiology of adult cellulitis.

Needle aspiration of cellulitis sites is commonly advocated to assist in the identification of causative organisms. Twenty-five nondiabetic, adult patients with a clinical diagnosis of cellulitis had site aspirations and blood cultures obtained before antibiotic therapy was initiated. Site cultures were positive in 6 of 25 patients. Blood cultures were positive in 4 of 25 patients. All organisms except one (Enterobacter agglomerans) were staphylococci or streptococci. The gram-negative bacilli were not believed to be a pathogen based on the patient's prompt response to nafcillin. In adult patients who do not have complications, the use of needle aspiration was not supported. Empiric treatment of cellulitis aimed at gram-positive cocci appears to be sufficient.

Imipenem susceptibility testing with a commercially prepared dry-format microdilution tray.

MICs of imipenem, concurrently generated in commercially prepared microdilution trays containing predried antibiotic dilutions (Sensititre), and in a standard agar dilution assay (as recommended by the National Committee for Clinical Laboratory Standards, Villanova, Pa.), were within +/- 1 twofold dilution for 94% of 226 bacterial isolates. Imipenem biological activity remained stable over 5 months of tray storage at room temperature against Pseudomonas aeruginosa ATCC 27853. Activity of imipenem was shown by microdilution testing with 890 clinical isolates to be high, with only 4% of isolates having MICs of greater than or equal to 16 micrograms/ml (in vitro resistance).

Performance characteristics of a commercially prepared biphasic blood culture bottle.

A biphasic blood culture bottle (BiPB: GIBCO Laboratories, North Andover, Mass.) with an architectural design that physically separates the agar slant from the broth was compared with a conventional vented monophasic bottle (MPB-A) for use in the routine culture of blood. Both bottles contained tryptic soy broth. Tryptic soy agar was used for the BiPB slant. A third unvented bottle (MPB-N) with Columbia broth was included as part of the blood culture set. Of 3,537 sets collected, 444 were positive; 57 of these 444 sets were positive by virtue of an exclusively positive anaerobic bottle. Both BiPB and MPB-A were positive in 235 of the remaining 387 positive sets. A total of 521 isolates was recovered during the study. Of these isolates, 252 were recovered in both the BiPB and the MPB-A from the same set; 105 isolates grew in the BIPB but not in MPB-A, 95 isolates grew only in the MPB-A but not in BiPB, and 69 grew exclusively in the MPB-N. The BiPB allowed more rapid recovery of Candida spp., J-K diphtheroids, Pseudomonas spp. Making BiPB subcultures was easy enough to permit both early and daily subculture, which provided isolated colonies sooner than could be done by using the MPB-A. Isolated colonies and, therefore, identification and susceptibility results were available at least 1 day earlier for the BiPB isolates in approximately 50% of instances when both the BiPB and the MPB-A were positive. Staphylococcus epidermidis and streptococci were recovered more frequently in the BiPB, while gram-positive anaerobes were detected at a significantly (P less than 0.025) more frequent rate in the MPB-A than in the BiPB. Either bottle, however, should be used in conjunction with an anaerobic bottle for optimal recovery of anaerobic bacteria.

Antimicrobial susceptibilities of anaerobic bacteria: recent clinical isolates.

Minimal inhibitory concentrations of clindamycin, minocycline, metronidazole, penicillin, and carbenicillin were determined by agar dilution against 150 recent clinical isolates of anaerobic bacteria. Ninety-nine percent of Bacteroides fragilis and all B. melaninogenicus, Clostridium perfringens, and Fusobacterium were inhibited by clindamycin at 3.1 mug/ml. Only 58% of other clostridial species were inhibited by this concentration of clindamycin. Minocycline at 3.1 mug/ml inhibited 72% of C. perfringens, 81% of other Clostridium species, and 66, 75, and 100% of B. fragilis, B. melaninogenicus, and Fusobacterium, respectively. Metronidazole at 12.5 mug/ml inhibited all bacteria tested. B. fragilis was resistant to both penicillin and carbenicillin at 6.2 mug/ml. Concentrations of 25 mug/ml for penicillin and 100 mug/ml for carbenicillin were needed to inhibit more than 90% of B. fragilis. Organisms other than B. fragilis were moderately or extremely susceptible to the penicillins.

Simplified approach to identification of aerobic actinomycetes by thin-layer chromatography.

A system has been developed for the identification of aerobic actinomycetes in the clinical laboratory based on analysis of whole cells for diaminopimelic acid and carbohydrates and on the ability of the organism to decompose casein, tyrosine, and xanthine media. The whole-cell analyses were performed by a simple thin-layer chromatographic procedure that is described. Eighteen reference cultures were correctly identified and, subsequently, 35 isolates from clinical material were grouped by using this system. The method is well suited for use in routine clinical laboratories.

Inhibition of Neisseria gonorrhoeae by sodium polyanetholesulfonate.

Sodium polyanetholesulfonate (SPS), in concentrations commonly used in blood culture media, inhibited the growth of a significant number of isolates of Neisseria gonorrhoeae in an agar dilution system. This SPS toxicity, shown to be bactericidal when examined in broth culture, could be reversed by hemoglobin and gelatin. Gelatin in 1% concentration allowed optimal growth of SPS-sensitive isolates in the presence of 0.025% SPS. Of 50 clinical isolates of N. gonorrheae tested under simulated blood cultures conditions with SPS, 16 isolates failed to grow on subculture at days 1, 3, and 10 after inoculation. Recovery was delayed with eight isolates as compared to controls. Early subcultures at 4, 8, and 12 h failed to recover SPS-sensitive isolates, whereas 1% gelatin, added even as late as 8 h after inoculation, reversed the SPS toxicity. The data reported suggest that SPS at concentrations routinely used in blood cultures can delay or prevent isolation of N. gonorrhoeae, but 1% gelatin can eliminate this adverse effect.

Dose effects of LPS on neutrophils in a whole blood flow cytometric assay of phagocytosis and oxidative burst.

Whole blood phagocytosis (P) and oxidative burst (OB), a rapid and sensitive flow cytometric method for quantifying neutrophil activation, was modified for single laser systems by using propidium iodide labeled Staphylococcus aureus and 2',7' dichlorofluorescein diacetate. The purpose of the present study was to characterize this assay with respect to the stimulatory activity of bacterial lipopolysaccharide (LPS) on phagocytosis. Blood from healthy donors was preincubated with log doses of bacterial LPS B (0.1-1,000 ng/ml) or sterile pyrogen-free saline at 37 degrees C from 0-120 minutes. LPS increased both P and OB in a dose-dependent manner (up to 62 and 121%, respectively) at all time points tested, and this effect on P and OB could be detected even with no preincubation. This LPS-induced phagocytic activity could be blocked by the addition of polymyxin B (10 micrograms/ml) during preincubation. The priming effect of LPS was maximal at 45 min. P and OB were inhibited by preincubation with EDTA at doses greater than 2 mM (60 and 80% inhibition, respectively). These observations are consistent with the exquisite sensitivity of the neutrophil to endotoxin. This method can evaluate neutrophil response to immunomodulatory and chemotherapeutic agents in a physiological milieu. These findings re-emphasize the necessity of using pyrogen-free reagents in any study of neutrophil function.