Issues in cerebrospinal fluid management. CSF Venereal Disease Research Laboratory testing.

Three policies for decreasing unnecessary cerebrospinal fluid (CSF) management Venereal Disease Research Laboratory (VDRL) tests were compared. The first policy attempted to educate physicians about the use of serologic tests for diagnosing neurosyphilis but allowed the CSF VDRL to be performed either as a screening test or as a retrospective test. The second policy required that the CSF VDRL be performed as a retrospective test without regard to the patient's serologic status. The third policy required that a patient be seropositive by either rapid plasma reagin (RPR) or fluorescent treponemal antibody absorbance (FTA-ABS) before a CSF VDRL could be performed. Before these policies were instituted, VDRL testing was performed on 18.2% of all CSF samples. The optional and required retrospective policies decreased the CSF VDRL rate to 13.0% and 8.5%, respectively, but the percentages of seropositive patients for whom these procedures were performed were only 7.3% and 12.9%. The third policy decreased the CSF VDRL test rate to 1.8% (P less than 0.001) with seropositivity improving to 90%. To assure serologic tests are obtained in the evaluation of neurosyphilis, requirement for seropositivity must be implemented with the use of retrospective CSF VDRL testing.

Evaluation of a new latex agglutination test for detection of streptococcal antibodies.

A liposome-enhanced latex agglutination test (Leapstrep, Cooper Biomedical, Inc., Malvern, PA) was evaluated for its efficacy as a screening test for antistreptolysin O (ASO) and antideoxyribonuclease B (ADNB) antibodies. A total of 179 sera were tested by both Leapstrep and reference ASO and ADNB test methods. The Leapstrep test had a sensitivity of 77% and a specificity of 69% for ASO antibodies when compared to a microtiter adaptation of the Todd-Hewitt ASO tube test. It had a sensitivity of 76% and 75% specificity for ADNB antibodies as compared to the ADNB microtiter enzyme neutralization test. The overall sensitivity of Leapstrep for detecting ASO and/or ADNB antibodies was 73%. The Leapstrep test failed to detect elevated levels of ASO and/or ADNB antibodies in eight patients with streptococcal infections or poststreptococcal sequelae. The Leapstrep test appears to have insufficient sensitivity to be recommended as a screening test for streptococcal antibodies.

Examination of preserved stool specimens for parasites: lack of value of the direct wet mount.

To review the appropriateness of standard reference procedures for diagnostic parasitology, we examined 2,206 stool specimens in our laboratory by direct wet mounting with saline and iodine, by saline and iodine wet mounting from Formalin-ethyl acetate concentrates, and by permanent staining with Wheatley's modified trichrome method (W.B. Wheatley, Am. J. Clin. Pathol. 21: 990-991, 1951). Parasites were detected in 98 stool specimens (4.4%). In all but three specimens, direct wet mounting with saline and iodine contributed little significant information to the result yet consumed substantial technical time. We recommend that with preserved feces a direct examination not be performed but that examination of both a concentrate and a permanent stain be routine.

Bioluminescence screening for bacteriuria.

A rapid screening test (45 min) for bacteriuria was evaluated in 1,000 clinical urine specimens. The test procedure is based upon firefly luciferase analysis of bacterial ATP and uses the Lumac kit and Lumac M2010 Biocounter (3M Co., St. Paul, Minn.). The procedure allows for removal and destruction of nonbacterial ATP and subsequent analysis of bacterial ATP by firefly luciferase with a single photon counter. Results, expressed in relative light units, were compared with actual CFU by the calibrated loop technique. Sensitivities and specificities were calculated separately for clean-catch midstream specimens and for urines obtained by catheterization. The sensitivity for 719 clean-catch specimens with a Lumac cutoff of greater than or equal to 500 relative light units, representing greater than or equal to 10(5) CFU/ml, was 93%. The sensitivity for 281 catheterized specimens with a Lumac cutoff of greater than or equal to 200 relative light units, representing greater than or equal to 10(4) CFU/ml, was 95%. There were 19 false-negative results in the 1,000 specimens tested; more than 50% of these were contaminated cultures and were not considered significant in determining bacteriuria. In conclusion, the Lumac bioluminescence assay is a reliable, rapid bacteriuria screening technique with the potential of reducing the laboratory cost and for reducing the turnaround time in processing negative urine cultures.

A clinical study of Laotian refugees infected with Clonorchis sinensis or Opisthorchis viverrini.

Twenty-six Laotian refugees infected with Clonorchis or Opisthorchis liver flukes, and 15 uninfected controls, were assessed clinically by history, physical examination, serum 5'nucleotidase level, and serum immunoglobulin E level. Ultrasound studies of the biliary tract were also done on a subset of six infected subjects. The results showed no differences between subjects and controls with respect to clinical symptoms, physical findings, 5'nucleotidase, or biliary ultrasound. Mean serum IgE levels were four times higher in fluke-infected individuals than uninfected controls (P less than 0.002). Even when those infected with other parasites in addition to Clonorchis were excluded from the analysis, serum IgE levels remained three times higher in fluke infected individuals (P = 0.06). This study provides some evidence that the fluke provokes a mild immune response in the asymptomatic human host but may not require eradication.

Method for concentration of parasites from small amounts of feces.

A total of 258 formalinized stool specimens received in our clinical laboratory were examined for parasites by direct smears and by the standard Formalin-ethyl acetate (FEAc) concentration method. Microconcentration (MC), a miniaturization of the FEAc method, was compared with the standard method for efficiency of parasite recovery. MC employed 0.25 to 0.50 ml of formalinized stools, 0.5 ml of Formalin, and 0.25 ml of ethyl acetate; the washing steps were omitted, whereas the rest of the procedure remained the same as the FEAc method. A total of 36 (13.9%) specimens were positive for parasites; of these, 23 (63.9%) were negative on direct examination. In 14 of these 23 specimens, the FEAc and MC methods were equivalent in detecting parasites. MC failed to detect parasites in eight specimens that were positive by FEAc and detected a parasite in one specimen that was negative by FEAc. Of 14 specimens positive by both concentration methods, FEAc detected additional parasite species in 2 specimens and MC did so in 1 specimen. The reduced sensitivity of parasite concentration evident in the MC we believe to be exclusively due to the drastically reduced sample size. We propose MC as an alternative to the FEAc concentration method when only small amounts of feces can be obtained.

Intestinal parasites in a remote village in Nepal.

Stool samples for parasitological examination were collected in a remote area of western Nepal. Of 40 specimens collected, 36 were positive for parasites as determined by examination of direct wet mounts and trichrome smears. All but one of the positive specimens contained several parasite species, averaging four species per specimen. Four negative specimens were found in infants under 1 year of age. The parasitic burden in this population appeared to be high, and the prevalence of parasitic infection approached 100%.

A program for in-house proficiency testing in clinical microbiology.

A design for an in-house blind proficiency testing program in clinical microbiology has been developed using a multi-level approach to proficiency testing, with progressive levels of organism identification difficulty. Flexibility of design allows the program to be used in any laboratory by starting the program at the appropriate level of difficulty. The necessary steps to initiate a similar testing program are detailed and benefits of the program are analyzed.