Search

One hundred BacT/ALERT blood culture bottles growing gram-positive cocci in clusters were cultured and studied by LightCycler PCR for the sa442 and mecA genes. PCR was 100% sensitive and specific for detecting Staphylococcus aureus and methicillin resistance in S. aureus but was less accurate for methicillin resistance in coagulase-negative staphylococci.

A new fluorescence in situ hybridization (FISH) method that uses peptide nucleic acid (PNA) probes for identification of Candida albicans directly from positive-blood-culture bottles in which yeast was observed by Gram staining (herein referred to as yeast-positive blood culture bottles) is described. The test (the C. albicans PNA FISH method) is based on a fluorescein-labeled PNA probe that targets C. albicans 26S rRNA. The PNA probe is added to smears made directly from the contents of the blood culture bottle and hybridized for 90 min at 55 degrees C. Unhybridized PNA probe is removed by washing of the mixture (30 min), and the smears are examined by fluorescence microscopy. The specificity of the method was confirmed with 23 reference strains representing phylogenetically related yeast species and 148 clinical isolates covering the clinically most significant yeast species, including C. albicans (n = 72), C. dubliniensis (n = 58), C. glabrata (n = 5), C. krusei (n = 2), C. parapsilosis (n = 4), and C. tropicalis (n = 3). The performance of the C. albicans PNA FISH method as a diagnostic test was evaluated with 33 routine and 25 simulated yeast-positive blood culture bottles and showed 100% sensitivity and 100% specificity. It is concluded that this 2.5-h method for the definitive identification of C. albicans directly from yeast-positive blood culture bottles provides important information for optimal antifungal therapy and patient management.

Context: Tunga penetrans is a flea that burrows into human skin, causing the disease tungiasis. Although the parasite is not endemic in the United States, patients may present with this disease upon returning from tropical locales. Histologic sections contain a variety of flea parts that may present a diagnostic dilemma for pathologists unfamiliar with this disease., Objective: To determine the typical histologic features of T penetrans in biopsies from patients with tungiasis., Methods: We reviewed biopsy specimens from 7 patients with tungiasis and sought 8 distinct structures: the exoskeleton, hypodermal layer, respiratory tract (tracheae), digestive tract, striated muscle, head, posterior end, and developing eggs., Results: The exoskeleton, hypodermal layer, tracheae, digestive tract, and developing eggs were present in all biopsy specimens reviewed. Striated muscle, the posterior end, and head, however, were present in 57%, 43%, and 0% of the biopsies, respectively. In addition, we noted a unique, pale-staining layer in the exoskeleton at the posterior end of the organism that, to the best of our knowledge, has not previously been described and that may be of diagnostic value., Conclusions: Despite the absence of 3 key morphologic features in many (posterior end and striated muscle) or all (head) of our biopsies, the exoskeleton with a hypodermal layer, tracheae, and developing eggs were uniformly present, and together these features are sufficient for a diagnosis of tungiasis.

Identification of fungi in tissue sections can be difficult because of limited biopsy tissue with only a few organisms present, or mycelial elements may be the only forms present, rendering common organism types indistinguishable from one another. In situ hybridization may assist in the rapid and accurate identification of such fungi. In this study, DNA probes were directed against the 5S or 18S ribosomal RNA sequences of three groups of fungi with a high degree of specificity for each. Two of the three, Aspergillus and Zygomycetes species, are usually seen in tissue purely in their hyphal forms. The third, Candida species is seen less commonly as predominantly mycelial elements. Probes were tested on 61 formalin-fixed, paraffin-embedded tissue specimens, each with culture-proven involvement by one of these organisms (Candida species, n = 21; Aspergillus species, n = 27; Zygomycetes, n = 13). Accuracy of both in situ hybridization (ISH) and morphology, based on the examination of Grocott methanamine silver (GMS)- and periodic acid-Schiff (PAS)-stained slides, was compared with culture. The results showed that morphologic examination (GMS and PAS) showed a slightly greater sensitivity in detecting the presence of fungi (98%) compared with in situ hybridization (95%). DNA probes, however, were more accurate in correctly identifying those organisms present. Although ISH specific probes showed 97% positive predictive value (PPV), examination of GMS-and PAS-stained slides had an 86% PPV when compared with culture-based identification methods. These results show that ISH, directed against ribosomal RNA, provides a rapid and accurate technique for the identification of mycelial fungal organisms in histologic tissue sections. Its primary use lies in the ability to accurately distinguish between organisms that have similar or identical morphologic features by light microscopy.

The presence of HER2/neu gene amplification is prognostically and therapeutically significant for patients with breast cancer. We sought to determine whether a relationship exists between HER2/neu gene amplification and the histologic type and grade of tumor. The histologic features and corresponding HER2/neu amplification results of 401 cases of invasive breast carcinoma were reviewed. Lobular carcinomas were less likely than ductal carcinomas to have HER2/neu amplification. Amplification was less frequent in Scarff-Bloom-Richardson grade I ductal carcinomas than in grades 2 and 3. Metastatic carcinomas frequently displayed HER2/neu amplification (6/20 [30%]). Our results support a correlation between HER2/neu amplification and the histologic type and grade of breast cancer. We suggest reexamination of tumors diagnosed as Scarff-Bloom-Richardson grade I invasive ductal carcinomas or lobular carcinomas if the lesion displays HER2/neu amplification to assure the exclusion of a higher grade of lesion or of missed ductal components.

Invasive fungal infections are associated with high morbidity and mortality in immunocompromised patients. We describe an unusual case of concomitant invasive candidiasis and zygomycosis of the tongue and epiglottis that occurred in a young patient with neutropenia during chemotherapy for acute myelogenous leukemia and was successfully treated medically.

A new fluorescence in situ hybridization (FISH) method with peptide nucleic acid (PNA) probes for identification of Staphylococcus aureus directly from positive blood culture bottles that contain gram-positive cocci in clusters (GPCC) is described. The test (the S. aureus PNA FISH assay) is based on a fluorescein-labeled PNA probe that targets a species-specific sequence of the 16S rRNA of S. aureus. Evaluations with 17 reference strains and 48 clinical isolates, including methicillin-resistant and methicillin-susceptible S. aureus species, coagulase-negative Staphylococcus species, and other clinically relevant and phylogenetically related bacteria and yeast species, showed that the assay had 100% sensitivity and 96% specificity. Clinical trials with 87 blood cultures positive for GPCC correctly identified 36 of 37 (97%) of the S. aureus-positive cultures identified by standard microbiological methods. The positive and negative predictive values were 100 and 98%, respectively. It is concluded that this rapid method (2.5 h) for identification of S. aureus directly from blood culture bottles that contain GPCC offers important information for optimal antibiotic therapy.

Detection of Giardia and Cryptosporidium in clinical stool specimens using the ColorPAC and ProSpecT enzyme immunoassays revealed 98.7% agreement for Giardia detection and 98.1% agreement for Cryptosporidium detection. Sensitivities were uniformly 100%. The specificities of the ColorPAC immunoassay for Giardia and Cryptosporidium detection were 100 and 99.5%, respectively, and those for the ProSpecT assay were 98.4 and 98.6%, respectively. The false-positive reactions with the ProSpecT assay occurred with specimens that were grossly bloody.

Advances in public health have reduced the risk of contracting certain enteric diseases, but many remain, and new pathogens have emerged and/or recently have been discovered. The pathogenic agents are varied and consist of a variety of bacteria and select viruses and parasites. Selected use of microbiologic assays to detect these pathogens is encouraged. When tests are ordered non-judiciously, costs rapidly accrue. The age of the patient, time of year, travel history, and clinical presentation all provide clues to the etiologic agent. Microbiologic assays should be used judiciously to confirm or exclude the likely infectious agents.

Dematiaceous fungi are a cause of a variety of human infections, including phaeohyphomycosis, that may affect patients with solid organ or bone marrow transplants. Exophiala jeanselmei, the most common cause of the pheomycotic cyst/subcutaneous phaeohyphomycosis in the United States, has been shown to cause disease in transplant recipients. We report a lung-transplant patient with relapsing and invasive E. jeanselmei phaeohyphomycosis, who previously had a pheomycotic cyst excised and treated with oral fluconazole. The patient was subsequently treated with re-excision and an 8-month course of oral itraconazole without relapse as to date.

Objective: To evaluate the feasibility of performing multicolor interphase fluorescence in situ hybridization (FISH) on ThinPrep slides of transitional cell carcinoma (TCC)., Study Design: Slides from 20 voided urine specimens were prepared by the ThinPrep technique (Cytyc, Boxborough, Massachusetts, U.S.A.), pretreated using a pretreatment kit and subjected to hybridization with the multicolor FISH probe UroVysion (Vysis, Downers Grove, Illinois, U.S.A.). Archival slides were placed in xylene, destained in alcohol and washed prior to pretreatment. Urines from patients with cytology-positive, biopsy-proven grade 1 (n = 5), 2 (n = 7) and 3 (n = 5) TCC and negative cytology and biopsy (n = 3) were selected. Freshly prepared (n = 10) and archival (n = 10) slides were used., Results: All carcinoma cases were FISH positive (> 5 cells with complex abnormalities of > or = 2 studied chromosomes per slide). None of the normal samples were aneusomic. Gain of chromosomes 3, 7 and 17 constituted the majority of positive cases. Proper destaining and slight decrease in stringency wash conditions enabled reliable detection of signals in archival cases., Conclusion: Routine ThinPrep slides can be used for multicolor interphase FISH analysis of urine cytology specimens. Archival slides provide the opportunity to analyze by FISH the nature of atypical cells identified by cytology. This revised method allows FISH technology more accessibility for routine use in cytology laboratories.

We describe a patient with granulomatous mastitis due to Mycobacterium abscessus that presented as a mass lesion and was associated with a pierced nipple. To our knowledge, this is the first reported case of mastitis due to M. abscessus and the first association of this organism with body piercing.

Histoplasma capsulatum is an infrequent but serious cause of endocarditis. The definitive diagnosis requires culture, which may require a long incubation. We demonstrated the ability of the Histoplasma capsulatum AccuProbe to accurately identify this organism when applied directly on an excised valve that contained abundant yeast forms consistent with H. capsulatum.

The anatomic pathologist performs an important role in the diagnosis or exclusion of infectious diseases. The morphologic interpretation of biopsies and cytologic preparations allows for the definitive establishment or exclusion of a wide variety of diseases. Once the pathologist has determined that a disease is likely to be due to an infection and has characterized the inflammatory response, associated microorganisms or viral-associated cytopathic effects should be recorded. Although some microorganisms or their cytopathic effects may be clearly visible on routine hematoxylin and eosin-stained sections, additional histochemical stains are often needed for their complete characterization. Highly specific molecular techniques, such as immunohistochemistry, in situ hybridization, and nucleic acid amplification, may be needed in certain instances to establish the diagnosis of infection. Through appropriate morphologic diagnoses and interlaboratory communication and collaboration, the anatomic pathologist contributes greatly to the diagnosis and treatment of infectious diseases.

Objective: Invasive zygomycosis is rapidly progressive and is associated with angioinvasion and infarction. Invasive disease requires emergent surgical and medical intervention. Because it is important for surgical pathologists to recognize these fungi and their preferential sites of growth, the objective of this article is to describe the fungal morphology and histopathologic findings in biopsies from patients with zygomycotic disease, with emphasis on preferential sites of fungal growth., Design: Medical record and histologic review identified 20 patients with zygomycosis. Inclusion criteria included the presence of typical ribbonlike hyphae and positive culture, a clinical history of invasive zygomycosis, or both. The histologic features of disease and the fungal morphology were assessed., Results: Fungus ball (15%), rhinocerebral (55%), and pulmonary (30%) disease were the types of disease represented. The inflammatory responses were predominantly neutrophilic (50%), predominantly granulomatous (5%), pyogranulomatous (25%), or absent (20%). Invasive disease was characterized by prominent infarcts (94%), angioinvasion (100%), and, surprisingly, prominent perineural invasion (90%) in biopsies that contained nerves for evaluation. At least rare hyphal septa were always seen (100%), and most branches (95%) varied from 45 degrees to 90 degrees., Conclusions: As known to mycologists, zygomycetes are pauciseptate, rather than aseptate, molds. Therefore, the presence of an occasional septum is expected. Perineural invasion is a common finding in invasive zygomycosis, as are angioinvasion and infarcts. Therefore, prior to excluding the presence of these fungi in biopsies suspected to contain zygomycetes, the perineural space should be carefully examined.

We report a case of synovitis in a 64-year-old man who developed the infection while on steroid therapy for rheumatoid arthritis. Dolosigranulum pigrum, a gram-positive catalase-negative coccus, was isolated from two sets of blood cultures prior to antibiotic therapy. The patient was treated with 4 weeks of appropriate antibiotics, and the synovial inflammation resolved. Although synovial aspirates were never positive for any bacteria or fungi, the timing of positive blood cultures and absence of other pathogens suggest the possible etiology as D. pigrum.

The persistence of Plasmodium falciparum in the placenta after apparently adequate therapy with quinine has been described. We describe this phenomenon in the placenta of a 19-year-old woman with falciparum malaria, who was treated with a combination of quinidine and clindamycin. Although this therapy was effective and diminished her peripheral blood parasitemia from 3% at presentation to almost undetectable at the time of delivery, vast numbers of P. falciparum-infected erythrocytes were present in the maternal sinusoids of the placenta. This sequestration of infected erythrocytes produced a local parasitemia in the placenta of 70% to 80%. Additionally, rare Plasmodium-infected erythrocytes were also seen in the fetal blood of the placenta. We review malaria in pregnancy, parasitic involvement of the placenta and emphasize that Plasmodium-infected erythrocytes may persist in the placenta even after clearance of parasites from the peripheral blood.

Rahnella aquatilis infections are rare. We report the case of a 46-y-old African-American male with relapsed acute lymphoblastic leukemia who had R. aquatilis bacteremia after beginning reinduction chemotherapy. He was treated for 4 weeks with piperacillin-tazobactam and gentamicin. He recovered from the infection and had an allogenic bone marrow transplant a month later.

The susceptibilities of 27 Abiotrophia adiacens (proposed reclassification Granulicatella adiacens comb.nov., Collins & Lawson, 2000) and 12 Abiotrophia defectiva isolates were tested by microdilution in pyridoxal hydrochloride and lysed horse blood supplemented Mueller-Hinton broth. According to NCCLS interpretative criteria for Streptococcus spp. not Streptococcus pneumoniae, the susceptibilities of A. adiacens and A. defectiva were, respectively: penicillin, 55% and 8%; amoxicillin, 81% and 92%; ceftriaxone, 63% and 83%; meropenem, 96% and 100%; and 100% for both species with clindamycin, rifampin, levofloxacin, ofloxacin, quinupristin/dalfopristin, and vancomycin.

We studied the recovery of 1,270 fungal isolates from 176,144 Isolator blood cultures (0.72% positive) on bacterial and fungal media, under routine and differing incubation conditions. Except with Histoplasma capsulatum, chocolate agar incubated for only 3 days proved to be an excellent medium for the recovery of fungi from the Isolator system.

We evaluated stool specimens known to contain or be free of Campylobacter by traditional culture, using the ProSpecT Campylobacter microplate assay (Alexon-Trend, Ramsey, Minn.). This rapid enzyme immunoassay for the detection of Campylobacter-specific antigens demonstrated 96% sensitivity and 99% specificity and is an acceptable alternative method of Campylobacter detection.

Direct immunofluorescence assays (DFAs) are used in the clinical virology laboratory for the rapid detection of viruses. An assessment of the cellularity of specimens submitted for DFA is necessary for the most effective use of this assay. This assessment ensures that an adequate number of the appropriate cells are present for examination. During this assessment, clinical virologists may encounter unfamiliar cellular elements or cellular fragments. One of these elements, ciliocytophthoria, has been misinterpreted as a parasite in specimens submitted for cytologic testing. We describe a similar case in which a technologist thought that ciliocytophthoria possibly represented a ciliated parasite in a nasopharyngeal specimen sent for respiratory syncytial virus DFA. After a thorough morphologic examination, the staff dismissed the possibility of a ciliated parasite. We confirmed this entity as ciliocytophthoria using morphologic criteria and the Diff-Quik stain. This near misidentification of ciliocytophthoria as a ciliated parasite affords us the opportunity to raise the awareness of clinical virologists about ciliocytophthoria. Additionally, we briefly review useful features for differentiating ciliocytophthoria from the only ciliate parasitic for humans, Balantidium coli. Finally, we present the utility of a commonly used cytologic stain, the Diff-Quik stain, for the confirmation of ciliocytophthoria.

Escherichia coli and Klebsiella spp. were screened for ESBL based on routine susceptibility testing results. Isolates with intermediate or resistant susceptibilities for extended spectrum cephalosporins or aztreonam were reported as probable ESBL producers. By using the NCCLS proposed ESBL confirmatory method, we tested 61 screen-positive isolates from 42 patients, 30 randomly selected susceptible isolates, and 12 isolates with previously characterized beta-lactamases. Ceftazidime contributed to 97% of screen-positive isolates, whereas aztreonam added a single patient isolate. An ESBL was confirmed in 86% of K. pneumoniae, 100% of K. oxytoca, and 20% of E. coli screen-positive single patient isolates. None of the susceptible isolates were shown to produce ESBL. Based on these findings a comment regarding the presence of ESBL seems sufficient for Klebsiella spp. but confirmatory testing is indicated for E. coli. 0.25 microg/mL was used to indicate the presence of ESBL, the specificity of the assay increased to 100%. The NCCLS ESBL phenotypic confirmatory method was reproducible and accurate enough to be used in the clinical laboratory.

Background: Paragonimiasis is a parasitic infection with a predilection for pulmonary involvement. Paragonimus species occur throughout the world and exist in nature in a snail-crustacean-mammalian life cycle. Human disease is most frequently encountered in cultures that ingest raw or undercooked crustaceans. North American paragonimiasis, caused by an endemic Paragonimus species, Paragonimus kellicotti, predominantly causes disease in carnivorous and omnivorous animals but may cause human disease if the intermediate host, the crayfish, is ingested raw or undercooked., Case: A previously healthy, 21-year-old male was infected with P kellicotti and developed parasitic hemoptysis. The disease was contracted through the ingestion of local, undercooked crayfish. Diagnosis was established through the morphologic examination of eggs in the cytologic preparation of bronchioalveolar lavage fluid. The patient was successfully treated with praziquantel and recovered without incident., Conclusion: Paragonimiasis is a cause of parasitic hemoptysis worldwide. Paragonimiasis is infrequently encountered in North America and is usually not considered in the differential diagnosis of hemoptysis unless specific risk factors are known. The cytologist or cytopathologist, therefore, may be the first to encounter the diagnostic eggs and should be familiar with this disease.

Objective: To evaluate the sensitivity and specificity of reverse-transcription polymerase chain reaction (RT-PCR) and routine cell culture for the detection of enterovirus in cerebrospinal fluid., Methods: Thirty-eight cerebrospinal fluid specimens were included. Cell culture was inoculated immediately and incubated for 14 days. An aliquot was kept frozen for Amplicor RT-PCR. Chart review was performed to determine the validity of the results., Results: Nine of 38 specimens were positive for enterovirus by culture, and 14 were positive by RT-PCR. There were 7 discrepancies between the 2 methods. Six specimens were positive by RT-PCR and negative by the culture method. The 1 culture-positive but RT-PCR--negative specimen was determined to contain PCR inhibitors. All discrepant results were confirmed as true positives by chart review. Patients whose cerebrospinal fluid was negative by both methods had a final diagnosis other than enterovirus infection., Conclusion: Amplicor PCR is more sensitive than cell culture (93.3% vs. 60%) and is very specific. With the incorporation of appropriate controls for the detection of amplification inhibitors, RT-PCR could be a valuable tool in the diagnosis of enteroviral meningitis.

We describe aortic valve endocarditis caused by Bartonella quintana in a 31-year-old man. The diagnosis was made on the basis of polymerase chain reaction amplification of the B quintana citrate synthase gene from cardiac valve tissue, the compatibility of histochemical stains of cardiac valve tissue, and serologic studies.

HHV8 DNA sequences have recently been isolated from all types of Kaposi's sarcomas, and its association in the etiopathogenesis of this tumor has been established. However, little is known about the regulation of HHV8 replication in immunocompromised patients seropositive for this virus, and its impact on the development of Kaposi's sarcoma (KS). Through the study of a heart transplant patient who developed KS and in whom peripheral blood lymphocytes (PBLs) had been prospectively collected before and after transplantation, we have investigated the pathogenesis of HHV8. Our results indicate that (i) HHV8 can reactivate soon after transplantation; (ii) viral replication, as determined by quantification of HHV8 DNA load of PBLs, increases significantly after transplantation; and (iii) increased HHV8 DNA levels in PBLs are associated with the development of KS.

Although rarely encountered in the United States, urinary tract schistosomiasis occurs commonly in many countries in the eastern hemisphere. Travel and immigration may contribute to imported cases of schistosomiasis. Excessive morbidity and increased mortality, including the development of urinary-tract squamous-cell carcinoma, are associated with untreated Schistosoma haematobium infection. Therefore, in the appropriate clinical context, all efforts should be made to rule out infectious and readily treatable causes of chronic hematuria. The presence of characteristic eggs in the urinary sediment is the usual means of diagnosing a S. haematobium infection. Additionally, the small and less commonly encountered miracidium stage of S. haematobium may also be present in the urine, which is another means of diagnosing urinary tract schistosomiasis. The present report describes a case in which a miracidium was detected in a fresh, unstained urine specimen. As detection of miracidia can be made in specimens also processed by routine cytologic methods, it behooves cytologists to be aware of this entity for the diagnosis of schistosomiasis.

Kaposi's sarcoma (KS) is the most common neoplasm in patients with AIDS. Epidemiologic evidence and the recent identification of herpesvirus-like DNA sequences in patients with KS have suggested a role for viral agents in the etiopathogenesis of this disease. It is unclear if these sequences are present in all types of KS and if the copy number of these sequences has a correlation with disease severity (staging). In order to clarify these issues, we retrospectively analyzed, by PCR and Southern blotting, formalin-fixed, paraffin-embedded biopsy specimens from 12 patients previously diagnosed with KS by histopathologic examination of these specimens between the years of 1977 and 1996. We also analyzed tissue samples from these patients taken from dermal sites without KS lesions and control tissues from healthy subjects. Of the 12 patients, 6 had classic KS, 5 had AIDS-associated KS, and 1 had the endemic type of KS. We tested the specimens for other herpesviruses, including cytomegalovirus, human herpesvirus 6 (HHV-6), HHV-7, HHV-8, and Epstein-Barr virus. Of 20 biopsy specimens from patients previously diagnosed with KS, 19 were positive for HHV-8 sequences (95%), while PCR for the DNAs of other herpesvirus agents was negative. Uninvolved tissue from these patients and control tissue from healthy subjects gave negative results for all viruses. Semiquantitative analysis of Southern blots showed higher levels of HHV-8 DNA in those patients with multicentric and visceral involvement than in those patients with localized involvement. In addition, in patients with localized skin disease, the nodular stage had higher levels of HHV-8 DNA than the patch or plaque stages. Our data confirmed that HHV-8 is involved in the etiopathogenesis of all types of KS and that there is a correlation between HHV-8 DNA load and the severity and staging of this disease.

Tissue specimens from a wide variety of anatomic locations are frequently examined for mycobacteria using a combination of cultures and special stains. Auramine-rhodamine (AR) staining is a sensitive method for detecting acid-fast bacilli (AFB) in tissue sections. We reviewed 85 AR-positive and 275 randomly selected AR-negative biopsy specimens collected during the past 2 years at the Mayo Clinic, Rochester, Minn. Pathologic diagnoses and culture results were also reviewed. Biopsy specimens containing necrotizing granulomas yielded the highest positivity rate for AFB (61 [47.7%]), followed by nonnecrotizing granulomas (14 [17.7%]). Poorly formed granulomas (5 [16.1%]) and acute inflammation (5 [15.6%]) were less frequently positive. Cases with fibrotic or hyalinized granulomas, nonspecific chronic inflammation, nonspecific reactive or reparative changes, no significant histologic abnormality, or malignancy failed to disclose AFB. These specimens, which were consistently negative for AFB, were responsible for 25% of the samples submitted. Of the 360 tissue specimens submitted, 166 had a corresponding mycobacterial culture. Mycobacteria were cultured only from the biopsy specimens that contained necrotizing granulomas (38.2%), nonnecrotizing granulomas (32.4%), poorly formed granulomas (30.0%), or acute inflammation (15.8%). Tissues with fibrotic or hyalinized granulomas, nonspecific chronic inflammation, nonspecific reactive or reparative changes, no significant histologic abnormality, or malignancy failed to yield positive cultures. These data suggest that biopsy specimens with these latter diagnoses are inappropriate specimens for mycobacterial culture or AR staining.

Over the past several years, the development and application of molecular diagnostic techniques has initiated a revolution in the diagnosis and monitoring of infectious diseases. Microbial phenotypic characteristics, such as protein, bacteriophage, and chromatographic profiles, as well as biotyping and susceptibility testing, are used in most routine laboratories for identification and differentiation. Nucleic acid techniques, such as plasmid profiling, various methods for generating restriction fragment length polymorphisms, and the polymerase chain reaction (PCR), are making increasing inroads into clinical laboratories. PCR-based systems to detect the etiologic agents of disease directly from clinical samples, without the need for culture, have been useful in rapid detection of unculturable or fastidious microorganisms. Additionally, sequence analysis of amplified microbial DNA allows for identification and better characterization of the pathogen. Subspecies variation, identified by various techniques, has been shown to be important in the prognosis of certain diseases. Other important advances include the determination of viral load and the direct detection of genes or gene mutations responsible for drug resistance. Increased use of automation and user-friendly software makes these technologies more widely available. In all, the detection of infectious agents at the nucleic acid level represents a true synthesis of clinical chemistry and clinical microbiology techniques.

Bronchoalveolar lavage (BAL) material is commonly received in cytopathology for the exclusion of microorganisms. When crystalline material suggestive of calcium oxalate is present in the specimen, a search for fungal elements should be undertaken. Aspergillus niger is the hyaline mold associated with the presence of oxalate crystals. Commonly fragments of hyphae and occasionally entire conidiophores may be present in BAL specimens from patients with aspergillosis. We report a case of a patient with saprophytic colonization of a bullous/cavitary lesion. The BAL consisted of abundant acute inflammation, crystalline material suggestive of oxalate, and darkly pigmented conidia. Although an extensive search was undertaken, hyphal fragments could not be found. The suspicion of an A. niger infection was confirmed by culture. We believe that even in the absence of hyphal fragments, darkly pigmented, occasionally rough-walled conidia are sufficient evidence to be highly suspicious of an A. niger infection in patients with pulmonary oxalosis.

Objective: To compare immunofluorescent and immunoperoxidase staining of Rickettsia rickettsii in skin biopsies of patients suspected of having Rocky Mountain spotted fever (RMSF)., Design: Immunofluorescent staining results for R rickettsii from skin biopsies of patients suspected of having RMSF were obtained by computer and chart review. Immunoperoxidase staining for R rickettsii was performed on formalin-fixed, paraffin-embedded skin biopsies from the same patient population., Patients: Twenty-six patients who were clinically suspected of having RMSF were included in this study. Skin biopsies of these patients were examined for evidence of RMSF by immunofluorescence and routine histology., Main Outcome Measures: The sensitivity and specificity of both immunofluorescent and immunoperoxidase staining techniques were calculated. The chi 2 method was used to assess significance., Results: Both tests were highly significant for the detection of R rickettsii (P < .01). The sensitivity and specificity of the immunofluorescent and immunoperoxidase staining techniques for the identification of RMSF were identical. No significant difference between these tests was identified (P > .05)., Conclusion: The sensitivity and specificity of immunofluorescent and immunoperoxidase staining of R rickettsii in routinely processed, paraffin-embedded skin biopsies of patients suspected of having RMSF are identical. Although not as rapid as the immunofluorescent technique, immunoperoxidase staining of R rickettsii has advantages over the immunofluorescent technique; these include easier antigen localization and concomitant viewing of the corresponding histopathology.

The rising costs of health care and the movement for health care reform have focused attention on methods of cost containment. Of routine laboratory and radiologic procedures, complete blood cell count (CBC) and determination of serum electrolyte values rank as high as 2nd and 9th in overall cost. We retrospectively studied use of the clinical laboratory to aid diagnosis of an acute infectious event in a pediatric emergency department population. For 5 months, we reviewed medical records of pediatric patients younger than 15 years brought to the emergency department because of a febrile episode. Of 155 cases reviewed, electrolyte concentrations were determined in 108 patients and CBC in 155. In all patients, either culture or rapid test for streptococcal organisms was performed. In addition, 838 pediatric patients with similar symptoms but who did not undergo laboratory testing were monitored for 100 days. Measures of effectiveness including sensitivity, specificity, positive and negative predictive values, and likelihood ratio were used to correlate specific laboratory findings with antibiotic therapy, serious bacterial disease, and culture positivity. Electrolyte abnormalities were found largely to be dismissed clinically, with the major clinical response consisting of parental education about hydration. The CBC profile was evaluated, with white blood cell count (WBC) indicator limits of > 10,000, > 10,000 but < 15,000, and > 15,000/mm3, and differentiated into absolute neutrophil count, neutrophil percent, and band cell percent. Temperature was evaluated as an independent variable. Insofar as serious bacterial disease and culture positivity, sensitivity was uniformly low (70%), and specificity was only marginably acceptable for WBC > 15,000 (77%). Both positive predictive values and likelihood ratio were low with respect to predicting either serious bacterial disease or culture positivity, emphasizing the limited usefulness of these clinical laboratory measurements. The best hematologic predictors of serious bacterial disease or culture positivity were obtained with automated hematologic analyzers and exceeded manual differential measurement of neutrophil percent and band cell percent. In addition, we correlated the administration of antibiotics with the various hematologic parameters and discovered that WBC > 15,000, regardless of cause, almost uniformly resulted in treatment (positive predictive value, 93.5%; likelihood ratio, 5.60). These findings support the use of automated hematology analyzer-derived measurements and question the use of manual differential counts, unless specific issues are to be addressed. Furthermore, the findings seem to support more reliance on clinical impression and less on laboratory values.

Background: Acute renal failure has long been associated with severe Rocky Mountain spotted fever (RMSF). Despite many descriptions of the protean manifestations of this disease, relatively little is known concerning the risk factors for acute renal failure. Only a few studies have examined the outcome of patients infected with Rickettsia rickettsii who develop renal insufficiency, and these studies had methodological problems., Objective: To study the incidence, risk factors, and outcomes of acute renal failure in a large group of hospitalized patients with definite or probable RMSF., Methods: The clinical records of 114 patients with definite or probable RMSF were retrospectively reviewed to identify clinical and biochemical abnormalities at the time of admission that were associated with the development of acute renal failure and subsequent mortality. Renal failure was defined as a serum creatinine (Cr) above 2 mg/dL. Logistic regression was used to study the association between these variables and the outcomes during hospitalization: death and the development of acute renal failure., Results: The mortality rate in this series was 14%; 19% of the patients developed acute renal failure. The development of acute renal failure increased the odds ratio (OR) of dying by a factor of 17 (P = 0.001). Factors at the time of hospitalization that were associated at a univariate level with subsequent mortality included elevated serum Cr, increased age, increased level of AST, increased level of bilirubin, decreased serum sodium and platelet count, the presence of neurological involvement, and being male. Both the presence of neurological involvement and an elevated serum Cr at presentation were independently associated with increased mortality by multivariate analysis. Three patients developed acute renal failure that required hemodialysis, and only 1 of these 3 patients survived; he was ultimately discharged with a normal serum Cr. Factors at presentation that were associated with the development of acute renal failure included increased bilirubin, increasing age, thrombocytopenia, and the presence of neurological involvement. Both age and decreased platelet count at presentation were independently associated with the development of acute renal failure by multivariate analysis., Conclusion: Acute renal failure was a frequent complication of RMSF in this series of patients from a tertiary referral medical center. The presence of acute renal failure was strongly associated with death. Clinical and biochemical variables are useful in predicting which patients will develop acute renal failure.