The detection of airborne Mycobacterium tuberculosis using micropore membrane air sampling and polymerase chain reaction.

STUDY OBJECTIVES: Mycobacterium tuberculosis (MTb) bacilli are carried on airborne droplet nuclei produced by aerosolization that can occur from coughing, talking, or even singing. Because of their prolonged period of suspension, they can be filtered from the air onto a porous medium and readily detected using polymerase chain reaction (PCR). DESIGN: Prospective cohort analysis. SETTING: Samples of circulating air were collected over a 12-month period from within the rooms of 10 hospitalized patients who were under respiratory isolation to rule out MTb infection. A small laboratory pump was used to draw ambient air at a rate of 2 L/min over a 6-h period through a 0.2-microm polycarbonate membrane filter placed near the patient's bed. Analysis of the membrane filters was conducted using PCR. Sputum cultures for MTb were performed simultaneously, and the results of smears stained for acid-fast bacilli (AFB) were noted. MEASUREMENTS AND RESULTS: MTb complex was successfully detected by PCR in six of seven patients in whom sputum MTb cultures were subsequently positive, and in zero of three with subsequently negative sputum cultures. Sampling in one patient with a positive culture, in whom PCR results were negative, was only carried out for 2 h due to pump malfunction. One of the six PCR-positive patients was AFB-smear negative at the time of air sampling. CONCLUSIONS: Our preliminary findings indicate that the technique of Micropore membrane air sampling with PCR analysis has important applications in the epidemiology and diagnosis of MTb.

Polymerase chain reaction and other amplification techniques in mycobacteriology.

Amplification methods for detection of Mycobacterium tuberculosis, such as polymerase chain reaction (PCR), have undergone much research and development in the last several years. The most common methods for extraction, amplification, and detection of mycobacterial nucleic acid sequences used in "in-house" PCR assays are discussed. A list of commercially prepared PCR and non-PCR amplification assays that should be available soon is included. The pros and cons of "in-house" versus commercial technology and issues of implementation of molecular technology in the clinical laboratory are reviewed.

Primary cutaneous aspergillosis: case report and review of the literature.

Primary cutaneous aspergillosis is an uncommon entity that may occur in immunosuppressed hosts, usually resulting from contact with contaminated medical devices used in patient care. The infection spreads locally with subsequent skin necrosis due to angioinvasion and thrombosis. We report primary cutaneous aspergillosis following contact with contaminated gauze, and we review the relevant literature.

Special considerations for the clinical microbiology laboratory in the diagnosis of infections in the cancer patient.

The clinical microbiology laboratory faces enormous challenges in diagnosing infections that cause morbidity and mortality in cancer patients. Such laboratories face several issues that surpass those faced by laboratories that perform more routine work. Issues such as sources of clinical specimens, need for correlation and interaction between laboratory and clinical services, blood cultures, susceptibility testing, and the role of new molecular diagnostic techniques are considered in this article.

Case report: anaerobic meningitis caused by Peptostreptococcus magnus after head and neck surgery.

Although anaerobic bacterial meningitis is uncommon, patients subjected to resection of head and neck malignancy appear at special risk. In this article, the authors report on a 72-year-old man in whom meningitis developed after extensive resection of the right sinuses for squamous cell carcinoma; initial treatment consisted of intravenous vancomycin and ceftazidime. Intravenous penicillin G was added after the fortuitous early finding of intracellular cocci in Wright-Giemsa stained cerebral spinal fluid submitted for cell count. Cerebral spinal fluid cultures then grew out a pure culture of Peptostreptococcus magnus. The patient had a complete recovery, without neurologic sequelae, recurrence of malignancy, or evidence of infection. Appropriate handling of cerebral spinal fluid specimens is crucial to ensure the correct diagnosis when anaerobic organisms are suspected.

Case report: cutaneous manifestations of cryptococcosis.

Cutaneous cryptococcosis usually is associated with concurrent systemic infection and actually may develop before clinical manifestations of cryptococcal meningitis become apparent. It is rare for a cryptococcal infection to be localized only to the skin. A case of cutaneous cryptococcosis is described in an immunocompromised patient who initially had a rash and a positive serum cryptococcal antigen titer, but no central nervous system involvement. The papular pustular skin lesions disappeared after 8 weeks of therapy with amphotericin B, which was stopped secondary to progressive azotemia. Less than 2 months after therapy, the skin lesions recurred, again without evidence of systemic disease. Treatment with oral fluconazole resulted in a gradual resolution of the cutaneous lesions. The pathogenesis of cryptococcosis is discussed, with emphasis on the management of cutaneous cryptococcosis.

Liver abscess following blunt trauma: a case report and review of the literature.

We report a case of Haemophilus paraphrophilus causing primary liver abscesses after blunt nonpenetrating trauma. A 32-year-old previously healthy white man sustained a back injury 2 months prior to admission with fever, chills, and night sweats. A computed tomography (CT) scan-directed needle aspirate of several hypoechoic hepatic lesions grew H paraphrophilus. Recent blunt trauma to the lower back may have contributed to the localization of this infection to an area of contusion or hematoma within the liver, followed by an episode of bacteremia that seeded the injury.

Pelvicobdominal actinomycosis associated with an intrauterine contraceptive device. A case of liver dissemination mimicking metastatic ovarian cancer.

A rare case of pelvicoabdominal actinomycosis with liver dissemination is reported in a patient with an intrauterine contraceptive device (IUCD) in place for 10 years. Her initial preoperative diagnosis of metastatic ovarian cancer emphasizes the slow indolent destructive nature of actinomycosis mimicking a malignancy. A history of an indwelling IUCD for several years along with a pelvic mass should prompt consideration of actinomycosis as a possible etiology.

Aberrant Histoplasma capsulatum. Confirmation of identity by a chemiluminescence-labeled DNA probe.

A cottony, light tan, filamentous fungus with pear-shaped microconidia and lacking tuberculated macroconidia was isolated from a bronchial lavage specimen. Subculture on several media at 37 degrees C failed to convert the fungus to a yeast form after several weeks; attempts at in vivo conversion in mice were also unsuccessful. Sera obtained several months apart showed M bands with Histoplasma capsulatum (HC) antigen by immunodiffusion and an increase in complement fixation titers with mycelial and yeast phase antigens of HC. Parallel identity was obtained on two occasions with exoantigen culture confirmation reagents for HC from Immuno-Mycologics as well as one of identity with Nolan reagents. Extracts from four Chrysosporium spp. strains had no identity reactions with HC with either kit. The fungus was identified as HC by the Accuprobe Histoplasma chemiluminescence-labeled DNA probe directed at ribosomal RNA, whereas all four Chrysosporium spp. isolates tested negative. DNA probes are a fast and accurate method to confirm the identity of aberrant fungal isolates.