Effects of delayed-entry conditions on the recovery and detection of microorganisms from BacT/ALERT and BACTEC blood culture bottles.

Manufacturers generally recommend that blood culture bottles be loaded into instruments within a short time of collection. However, in our experience, delays often occur prior to loading the bottles. We examined the effect of holding bottles under various temperatures (T)-room temperature (RT), 4 degrees C, 37 degrees C, and RT for 2 h following incubation at 37 degrees C (to simulate transit [TR])-and for various holding times of 4, 12, and 24 h. We utilized the BacT/ALERT system with FA and FN bottles and the BACTEC system with Plus (PL) and Lytic 10 (LY) bottles. Standardized inocula and 5 ml of blood were added to each bottle. Fifteen organisms were evaluated based upon expected performance: aerobic (FA and PL), anaerobic (FN and LY 10), and facultative (all bottles). Based upon expected performance, the FA and FN bottles recovered 458 of 468 organisms and 282 of 288 organisms, respectively, whereas the PL and LY bottles recovered 453 of 468 organisms and 257 of 288 organisms, respectively (P = <0.001, FN versus LY). There were 3, 11, 21, and 27 false-negative results for bottles held at 4 degrees C, RT, 37 degrees C, and TR, respectively. There were 4, 8, and 50 false-negative results for bottles held for 4, 12, and 24 h, respectively. Our results support holding these four bottle types at 4 degrees C or at RT for up to 24 h and at 37 degrees C for up to 12 h. We propose that manufacturers only need to make claims for "delayed entry" when these bottles are held for more than 24 h at 4 degrees C or at RT or for more than 12 h at 37 degrees C.

Trichosporon beigelii, a new neonatal pathogen.

Trichosporon beigelii is an uncommon cause of sepsis in low-birth-weight infants. We present two cases of neonatal trichosporonosis and two cases of neonatal trichosporon colonization to familiarize neonatologists with this entity and to discuss management considerations. A 23-week-gestation male developed clinical evidence of sepsis on day 10 and was found to have "yeast" growing in a blood culture on day 12. Despite receiving amphotericin B, he expired within 2 days, at which time the organism was identified as T. beigelii. A 23-week gestation female developed fungal septicemia in the second week of life, while being treated for persistent bacterial sepsis. Candida albicans grew from blood culture, while T. beigelii grew from suprapubic urine, tracheal aspirate, and umbilical catheter tip cultures. She died 2 days later despite therapy with amphotericin B, at which time the fungal isolates were correctly identified. Two other infants were found to have colonization of central vascular catheters, without evidence of invasive disease. Trichosporon infections in neonates have been almost uniformly fatal. Most strains of T. beigelii are relatively resistant to amphotericin B and may be confused with Candida sp. on initial culture examinations. Therefore, delays in appropriate treatment may occur. We discuss treatment options, including alternative antifungal drugs, as well as possibilities for combination therapy.

Comparison of five methods for the determination of rubella immunity.

OBJECTIVE: The purpose of this study was to compare the accuracy of commonly used methods for the detection of rubella immunity, especially the fully automated IMx assay. METHODS: A total of 190 sera (101 immune and 89 non-immune) submitted to Harrisburg Hospital or Polyclinic Medical Center for the determination of rubella immunity were tested by enzyme immunoassay (IMx and Rubazyme, Abbott Diagnostic Laboratories, North Chicago, IL), indirect immunofluorescence (FIAX, Whittaker Bioproducts, Walkersville, MD), and latex agglutination (Rubascan, Becton Dickinson Microbiology Systems, Cockeysville, MD, and Rubalex, Wellcome Diagnostics, Research Triangle Park, NC). Specimens were frozen at -30 until the study was initiated. Each of the assays was performed according to the manufacturers' specifications. Sensitivity, specificity, accuracy, and positive and negative predictive values for each assay were calculated using a consensus result of the 5 methods tested. RESULTS: The sensitivity, specificity, and accuracy, respectively, of the test systems were as follows: IMx, 96%, 97%, and 96%; Rubazyme, 100%, 99%, and 99%; Rubascan, 100%, 98%, and 99%; Rubalex, 99%, 97%, and 98%; and FIAX 90%, 100%, and 95%. False negative reactions were seen with the FIAX system. CONCLUSIONS: The IMx system, a new "walk away" system from Abbott Diagnostic Laboratories and the Rubazyme systems performed well; however the latex agglutination tests proved to be the most rapid and convenient methods for screening sera for the presence of rubella immunity.

Prevalence of Hepatitis C virus antibody in patients with sexually transmitted diseases attending a Harrisburg, PA, STD clinic.

OBJECTIVE: The prevalence of hepatitis B and hepatitis C in a sexually transmitted disease (STD) clinic population was studied, along with the prevalence of various STD agents, in an attempt to identify possible STD markers for the hepatitis C virus and help delineate the role of hepatitis C as an STD. The hepatitis C antibody rates found in the STD clinic were also compared with those found among patients attending a local OB/GYN clinic and those enrolled in a blood donor program, all from the same geographical area. METHODS: A total of 150 women attending an STD clinc were examined for each of the following agents: Chlamyadia trachomatis, Neisseria gonorrhoeae, syphilis, hepatitis B surface antigen, hepatitis B core antibody, hepatitis B surface antibody, and hepatitis C virus antibody. Additionally, several patients who signed informed consent to be evaluated for human immunodeficiency virus (HIV) antibody were tested by an enzyme immunoassay (EIA) screen method. The prevalence of each agent was then compared with the other agents. RESULTS: The overall prevalence rates detected were as follows: hepatitis B 16%, hepatitis C 4%, chlamydia 18.7%, gonorrhea 7.4%, syphilis 0.7%, and HIV 0%. Hepatitis C antibody was detected in 4% of patients in the STD clinic, 0.76% of volunteer blood donors from central Pennsylvania, and 0% of patiants studied from the Harrisburg Hospital (Harrisburg, PA) prentatal population. CONCLUSIONS: This screening study reveals an association between attending a Harrisburg, PA, area STD clinic and having an increased prevalence of hepatitis C antibody, but larger matched control studies will be needed to help clarify sexual transmission as a mode of transmission for the hepatitis C virus.

Salmonella poona infection and surveillance in a neonatal nursery.

BACKGROUND: This article reports the first known outbreak of Salmonella poona infection in a neonatal unit. Three babies had stool cultures positive for the organism. At the same time, S. poona was the cause of a nationwide food-borne outbreak associated with contaminated canteloupe. To minimize the neonatal outbreak, surveys were performed and control measures were instituted. METHODS: Epidemiologic surveillance included the culture of rectal swabs collected from 48 employees, 18 babies, and four family members of the babies. Control measures used included the placement in cohorts and isolation of infected babies, strict adherence to universal precautions, and the restriction of visitation in the nursery. RESULTS: A total of three babies and one employee in the surveillance were found to have Salmonella sp. An additional two hospitalized adult patients had S. poona. Of all the people included in the surveillance, only the three babies were found to have S. poona. The hospital employee had S. enteritidis. CONCLUSIONS: Timely culture results, rapid cohort placement of infected babies, and strict adherence to universal precautions led to the successful eradication of the organism.

Susceptibility testing of clinical isolates of Methylobacterium species.

Methylobacterium species represent a relatively new genus which is being increasingly isolated from cases of opportunistic infections. This study reports on 3 reference strains and 15 clinical isolates of Methylobacterium species. Susceptibility tests were performed by the agar dilution and commercial broth microdilution methods at both 30 and 35 degrees C. Readings were made at 24, 48, and 72 h. Incubation conditions of 48 h and 30 degrees C were found to be optimum. Both the agar dilution and broth microdilution methods gave equivalent results. Drugs tested and their MICs for 90% of isolates (in micrograms per milliliter) were as follows: amikacin, less than or equal to 1; gentamicin, 1; ciprofloxacin, 1; trimethoprim-sulfamethoxazole, 2/38; ceftriaxone, 16; and ceftizoxime, 16. The majority of our isolates were resistant to six other beta-lactam drugs tested. Nine of the 15 Methylobacterium isolates were beta-lactamase positive.

Evaluation of latex agglutination and dot immunobinding assay for the detection of cytomegalovirus antibody.

The Virogen CMV Antibody Test and Difco CMV-Cube were compared with three other available methods, enzyme immunoassay, immunofluorescence and latex agglutination, for the detection of cytomegalovirus (CMV) antibody in 126 random sera submitted to the clinical laboratory. Based on concordance of three or more methods, 72% of the samples were positive for CMV antibody. The sensitivities and specificities of the assays were Virogen, 98% and 97%, and CMV-Cube 97% and 97%, respectively.

Comparison of a rapid latex agglutination assay and a fluorescent-antibody technique for the detection of herpes simplex antibody.

A total of 202 serum specimens was tested for the presence of herpes simplex virus antibody using a premarket latex agglutination kit (Wampole) and an indirect fluorescent antibody (IFA) technique (electronucleonics). Discrepant results between the two assays were resolved using an Enzyme-linked immunosorbent assay (ELISA) procedure. The overall sensitivity of the latex was 99.2% with a specificity of 98.5%. The latex agglutination test evaluated is a viable alternative to indirect immunofluorescence for the detection of herpes simplex virus antibody in serum samples.

The use of a selective staphylococcal broth v direct plating for the recovery of Staphylococcus aureus.

Nine hundred seventy-two cultures taken from the external nares and the vaginal vestibules of 54 women for the isolation of Staphylococcus aureus were studied. The swabs were plated directly to a trypticase soy agar plate containing 5% sheep blood and were then placed into a selective staphylococcal broth. Both culture methods were compared for the ability to recover S aureus. Twenty percent (26/131) and 66% (38/58) of the S aureus-positive cultures taken from the nares and vagina respectively were cultured from the selective broth only. We believe that a selective staphylococcal broth should be used in addition to routine culture techniques to isolate S aureus from infection control surveillance cultures.

Vibrio parahaemolyticus (Kanagawa-negative) wound infection in a hospital dietary employee.

Vibrio parahaemolyticus is an estuarine bacterium that is a major cause of gastroenteritis worldwide. Occasionally, this organism has also been shown to be the causative agent of wound infections. In almost all cases of gastrointestinal disease only strains that produce hemolysin ("Kanagawa-positive") are implicated. We have isolated a Kanagawa-negative strain of V. parahaemolyticus from serous wound drainage of the infected foot of a hospital dietary employee. To our knowledge, this is only the third documented case of wound infection caused by such an organism. In this instance, the potential threat of nosocomial transmission was of special concern in that the wound infection was present in a hospital food handler.

Anisakiasis.

Larval forms of nematodes of the Anisakidae family (cod or herring worms) can cause disease in people who eat raw or undercooked seafood. These nematodes are widespread along the eastern and western coasts of the United States, and the larvae can be found in fresh fish sold in any grocery store. Luminal infestation causes few symptoms. Invasive anisakiasis may be acute or chronic and may involve the stomach or the small intestine.

Evaluation of a rapid latex slide agglutination test for herpes simplex virus as a specimen screen and culture identification method.

A total of 449 clinical specimens and 199 culture fluids were tested using the Virogen Herpes Slide Test (Wampole Laboratories, Div. Carter-Wallace, Inc., Cranbury, N.J.), a rapid latex agglutination procedure. The results were compared with those obtained with isolation of herpes simplex virus in cell culture followed by identification using immunoperoxidase or fluorescent reagents. The sensitivity, specificity, and positive and negative predictive values of the direct test were 49.7, 93.4, 96.0, and 37.1%, respectively. The sensitivity and specificity of the latex agglutination test for culture confirmation were 75.9 and 100%, respectively.

Comparison of BIOGRAM and commercial microdilution antimicrobial susceptibility test systems.

The BIOGRAM (Difco Laboratories, Detroit, Mich.) system, which is designed to calculate MICs from disk diffusion zone diameters, was compared with two commercial microdilution antimicrobial susceptibility systems. A total of 111 clinical isolates were evaluated with each test system. Six additional isolates were tested in a comparison between BIOGRAM and Sceptor (Johnston Laboratories, Inc. Towson, Md.) systems. BIOGRAM demonstrated an overall correlation with the Sceptor microdilution method of 95.7% for 1,287 organism-antimicrobial susceptibility combinations. The BIOGRAM and UniScept (Analytab Products, Inc., Plainview, N.Y.) systems were in agreement in 90.3% of 1,048 organism-antimicrobial susceptibility combinations tested. All methicillin-resistant staphylococci were detected by the standard disk agar diffusion method used with the BIOGRAM system. The BIOGRAM system provides an acceptable alternative to these commercial systems for the determination of quantitative susceptibility.

Serratia marcescens meningitis associated with a contaminated benzalkonium chloride solution.

Serratia marcescens is recognized as an important and potentially hazardous nosocomial pathogen. The organism has been implicated here as the first reported case of S. marcescens meningitis associated with skin disinfection. A quaternary ammonium compound ( QAC --Benzalkonium Chloride), was used to sterilize the skin prior to injection in a physician's office. Epidemiological studies were initiated. Six spray bottles containing disinfectant, the opened stock bottle of QAC , and an unopened bottle of disinfectant were all cultured. S. marcescens was noted growing in the spray bottles as well as in the opened stock bottle. Antibiograms of the patient and epidemiological isolates are essentially the same. It is our contention as well as that of the Centers for Disease Control that an appropriate skin disinfectant such as Tincture of Chlorhexidine, Iodophors , or Tincture of Iodine should be used, and that physicians performing surgical techniques in the office be aware of the potential hazard of contamination. The consequences of nosocomial infection with resistant organisms warrant every precaution by health care professionals.

Sequential vaginal cultures from normal young women.

Vaginal specimens were collected two to three times a week for 1 month from seven nurses. A total of 65 specimens were collected. Each sample consisted of three swabs and a saline wash. Semiquantitation of anaerobic and aerobic bacteria, mycoplasma and ureaplasma, and yeast was performed. Numerous species were recovered in each specimen; at least 37 species were isolated. Lactobacilli, Corynebacterium, Ureaplasma, Mycoplasma, Bacteroides melaninogenicus, and Candida albicans, when present, tended to remain throughout the entire month. Other organisms were present on a more sporadic basis. The number of organisms varied greatly during the sampling for each individual, whereas the types of organisms isolated from a particular subject remained relatively constant.

Five-hour minimal inhibitory concentration test of four antimicrobial agents for Pseudomonas aeruginosa.

A rapid 5-h minimal inhibitory concentration procedure and a minimal bactericidal concentration procedure are described for testing Pseudomonas aeruginosa against gentamicin, tobramycin, amikacin, and carbenicillin. The rapid test results were demonstrated to correlate with the conventional tube dilution procedure.