Risk of suicide attempts after benzodiazepine and/or antidepressant use

To understand the clinical features, antimicrobial therapy, and epidemiology of Chryseobacterium indologenes infections, the medical records of 36 patients with nosocomial Chryseobacterium indologenes infections seen over a three-year period at National Taiwan University Hospital were reviewed. The 36 isolates recovered from these patients were studied by molecular typing and determination of antimicrobial susceptibility patterns. Nine patients had underlying neoplastic diseases, seven had diabetes mellitus, five had burn wounds, and four had uremia. The clinical syndrome included ten patients with intraabdominal infections, nine with wound sepsis, six with intravascular catheter-related bacteremia, and four with ventilator-associated pneumonia. Thirteen patients had monomicrobial bacteremia, and four had polymicrobial bacteremia. Nineteen patients (53%) developed infections associated with various indwelling devices. The deaths of five patients (14%) were directly attributable to infection with Chryseobacterium indologenes. All isolates recovered showed a wide range of resistance to commonly used antimicrobial agents. The random amplified polymorphic DNA (RAPD) patterns of the isolates differed from each other, indicating the absence of epidemiological relatedness among these isolates. Nosocomial infection caused by multiresistant Chryseobacterium indologenes appears to be an emerging problem in Taiwan and should be studied further.     

Flavimonas oryzihabitans bacteremia: clinical features and microbiological characteristics of isolates

Flavimonas oryzihabitans is rarely reported as a pathogen in humans. Twelve cases of F. oryzihabitans bacteremia were diagnosed at National Taiwan University Hospital over a 3-year period. The clinical features of these patients were analyzed, and antimicrobial susceptibilities and random amplified polymorphic DNA (RAPD) patterns of the 12 isolates were studied. Among these 12 patients, eight (67%) had underlying neoplastic diseases and all acquired F. oryzihabitans bacteremia while hospitalized. The clinical syndromes included primary bacteremia in 5 patients (42%), biliary tract infection in 3 (25%), and peritonitis, subdural empyema, infusion-related bacteremia, and pneumonia in 1 each. Polymicrobial bacteremia or concomitant fungemia was seen in three patients (25%). All the patients survived after antibiotic treatment. All isolates were susceptible to piperacillin, third-generation cephalosporins, aminoglycosides, and quinolones but resistant to cephalothin, cefuroxime, and trimethoprim. Susceptibility to aztreonam was variable (25%). The RAPD patterns differed among the isolates, indicating the epidemiological unrelatedness of these infections. F. oryzihabitans should be included as an etiology of severe nosocomial infection in patients with underlying debilitating diseases.     

A spectroscopic study of the structures of latent, active and reactive-center-cleaved type-1 plasminogen-activator inhibitor

To our knowledge, Flavobacterium indologenes has never been reported as a cause of bacteremia in humans. F. indologenes bacteremia was diagnosed in 12 patients at a tertiary referral center in southern Taiwan between 1 January 1992 and 31 December 1994. Six of these patients had ventilator-associated pneumonia, two had primary bacteremia, and one patient each had pyonephrosis, peritonitis, biliary tract infection, and surgical wound infection. Five patients (42%) had malignancies, and three (25%) had multiple burns. Polymicrobial bacteremia was diagnosed in eight patients (67%). Two (17%) of the patients in this study died; both had polymicrobial bacteremia. Antimicrobial susceptibility testing of the blood isolates from the 12 patients showed that > 90% of the isolates were susceptible to piperacillin, cefoperazone, ceftazidime, and minocycline. The chromatograms of esterified fatty acids for the isolates were identical. F. indologenes should be considered an etiologic agent of bloodstream infection, especially in hospitalized patients with severe underlying diseases.     

Clinical and microbiological characteristics of Flavobacterium indologenes infections associated with indwelling devices

Clinical infections caused by Flavobacterium indologenes have never been documented. Thirteen isolates derived from seven patients with indwelling device-associated F. indologenes infections were identified from 1 April through 30 November 1995. The antimicrobial susceptibilities to 20 antimicrobial agents of the isolates, the cellular fatty acid chromatograms for the isolates, and the random amplified polymorphic DNA (RAPD) patterns generated by arbitrarily primed PCR of the isolates were studied. The antibiotypes and RAPD patterns differed among the isolates recovered from different patients. However, both antibiotypes and RAPD patterns were identical among the five isolates from one patient with multiple episodes of central venous catheter-associated bacteremia within a 1.5-month period and between the two isolates from another patient suffering from two episodes of catheter-related bacteriuria at an interval of 14 days. It is documented that the recurrent infections in each of these two patients were caused by a single F. indologenes clone, respectively. Identical antibiotypes and RAPD patterns were also demonstrated between two isolates from a patient with ventilator-associated pneumonia, one recovered from an endotracheal aspirate and the other derived from a blood specimen 10 days later, indicating the invasive nature of F. indologenes. Two cellular fatty acid chromatograms were identified among these isolates. All of the isolates showed in vitro resistance to cephalothin, cefotaxime, ceftriaxone, moxalactam, aztreonam, aminoglycosides, erythromycin, clindamycin, vancomycin, and teicoplanin. F. indologenes should be included as an etiologic agent of infections associated with the use of indwelling devices.     

Characterization of Scedosporium prolificans clinical isolates by randomly amplified polymorphic DNA analysis

Fingerprinting by randomly amplified polymorphic DNA (RAPD) analysis was used to differentiate Scedosporium prolificans isolates. A total of 59 arbitrary primers were screened with six unrelated S. prolificans isolates, and a panel of 12 primers was selected. The 12 primers were then used to detect DNA polymorphisms among 17 S. prolificans isolates from 11 patients with systemic S. prolificans infections diagnosed in three hospitals located in geographically different areas of Spain. Eight patients were diagnosed with S. prolificans infection in a single institution over a 6-year period, and two other patients were diagnosed with S. prolificans infection in a different hospital over a 1-year period. No single primer allowed for the discrimination of all the isolates from different patients, but this was possible by combining the RAPD patterns from three primers (UBC 701, AB1.08, and AB1.11 or UBC 701, AB1.08, and UBC 707). However, multiple isolates from the same patient were identical. In this study, we also compared a visual method and a computerized method for the analysis of the RAPD patterns. Both methods were satisfactory and gave few discordances, but given the advantages and disadvantages of each method, both systems should be used together. RAPD analysis provided a fast and economical means of typing S. prolificans isolates, with a high level of discrimination among unrelated isolates. Typing by RAPD analysis confirmed that the S. prolificans infections were epidemiologically unrelated.     

Analysis of an outbreak of non-phage-typeable methicillin-resistant Staphylococcus aureus by using a randomly amplified polymorphic DNA assay

A cluster of methicillin-resistant Staphylococcus aureus (MRSA) infections among patients on an intensive care unit (ICU) was detected by routine infection control surveillance. In the period from 5 January to 22 June 1995, 10 patients on the ICU and a further 6 patients (5 on one ward that had received colonized patients transferred from the ICU) were affected by MRSA strains with the same antibiotic susceptibility patterns. Seven (44%) of these 16 colonized patients developed MRSA bacteremia. MRSA isolates with the same characteristics were also found on the hands of one member of the ICU staff. The isolates were untypeable by phage typing, but 15 of 17 outbreak strains analyzed genetically had identical randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) profiles. A single strain of MRSA that was nontypeable by phage typing and that was isolated on the ICU on 1 January and six nontypeable and epidemiologically unrelated MRSA isolates all had RAPD profiles distinct from that of the outbreak strain. Implementation of strict infection control measures stopped the further spread of MRSA on the ICU, the affected general ward, and seven other wards that received MRSA carriers from the ICU. Although nontypeable by phage typing and not previously recognized as an epidemic strain, this strain of MRSA was readily transmissible and highly virulent. RAPD typing was found to be a simple, rapid, and effective method for the epidemiological investigation of this outbreak, and performance of typing by this method was simpler and less time-consuming than that of typing by PFGE. RAPD typing may have more general application for the study of S. aureus infections in hospitals.     

Bacteremia due to glucose non-fermenting gram-negative bacilli in patients with hematological neoplasias and solid tumors

Twenty-six patients with hematological or solid tumors who developed bacteremia caused by Stenotrophomonas maltophilia (n = 10), Pseudomonas putida (n = 6), Sphingomonas paucimobilis complex (n = 4) or Alcaligenes xylosoxidans (n = 6) in the period between 1993 and 1995 were studied. Seventeen patients were neutropenic during the infection, and 13 were undergoing bone marrow or peripheral blood stem cell transplantation. Twenty-three patients had catheter-related infections; only 3 of the 26 patients developed septic complications (all due to Stenotrophomonas maltophilia). Twenty patients were cured following catheter removal, either as primary measure (n = 8) or salvage measure (n = 12). Four responded to antibiotic therapy only, and two died of septic complications. Such infections in hematological and oncological patients have increased in this hospital from no cases in 1975 to 11 cases in 1995.     

Clonal expansion of Staphylococcus epidermidis strains causing Hickman catheter-related infections in a hemato-oncologic department

The detailed analysis of 411 strains of coagulase-negative staphylococci (CoNS) obtained from 40 neutropenic hemato-oncologic patients (61 Hickman catheter episodes) on intensive chemotherapy is described. By random amplification of polymorphic DNA (RAPD) analysis, a total of 88 different genotypes were detected: 51 in air samples and 30 in skin cultures prior to insertion, 12 in blood cultures after insertion, and only 5 involved in catheter-related infections (CRI). Two RAPD genotypes of Staphylococcus epidermidis predominated, and their prevalence increased during patient hospitalization. At insertion, these clones constituted 11 of 86 (13%) CoNS isolated from air samples and 33 of 75 (44%) CoNS isolated from skin cultures. After insertion, their combined prevalence increased to 33 of 62 (53%) in catheters not associated with CRI and 139 of 188 (74%) in catheters associated with CRI (P = 0.0041). These two predominant S. epidermidis clones gave rise to a very high incidence of CRI (6.0 per 1,000 catheter days) and a very high catheter removal rate for CRI, 70%, despite prompt treatment with vancomycin. A likely source of S. epidermidis strains involved in CRI appeared to be the skin flora in 75% of cases. The validity of these observations was confirmed by pulsed-field gel electrophoresis (PFGE) of SmaI DNA macrorestriction fragments of blood culture CoNS isolates. Again, two predominant CoNS genotypes were found (combined prevalence, 60%). RAPD and PFGE yielded concordant results in 75% of cases. Retrospectively, the same two predominant CoNS clones were also found among blood culture CoNS isolates from the same hematology department in the period 1991 to 1993 (combined prevalence, 42%) but not in the period 1978 to 1982. These observations underscore the pathogenic potential of clonal CoNS types that have successfully and persistently colonized patients in this hemato-oncology department.     

Bacteremia complicating peritonitis in peritoneal dialysis patients

Bacteremia is a rare complication of peritonitis in end-stage renal failure (ESRF) patients treated by peritoneal dialysis. Three of our ESRF patients on peritoneal dialysis developed bacteremia during a peritonitis episode (1/19 peritonitis episodes). In 2 cases, the responsible organism was Escherichia coli and peritonitis was most likely associated with infection of the biliary tract. The 3rd patient had a perforation of the colon and Klebsiella spp. was the infective organism. Only the last patient survived but had to be transferred to hemodialysis. Bacteremia during peritonitis is infrequent in peritoneal dialysis patients and it appears to be related to other intra-abdominal events.     

Effects of syntactic structure and propositional number on patterns of regional cerebral blood flow

BACKGROUND: Intravascular catheters are associated with severe infections in patients, but only few reports on this problem in animal research exist. OBJECTIVE: We report on catheter-related bacterial colonization and its consequences in long-term catheterized animals. MATERIAL AND METHOD: Foxhounds were instrumented with intravascular catheters and flow probes to study the regulation of renal blood flow and pressures. RESULTS: After flushing the catheters, alterations in renal blood flow were observed and these could be related to bacterial colonization of intravascular catheters with Pseudomonas species. After attention had been focused on aseptic technique in all experimental phases and prophylactic antibiotic lock instituted, the occurrence of Pseudomonas bacteremia ceased, and the magnitude and incidence of catheter-related colonization and infection by Pseudomonas species dropped considerably. CONCLUSION: The catheter-related colonization that occurred spontaneously in these animals resembled findings in animal experiments in which catheter-related infections were deliberately induced as well as observations made with regard to catheter-related infections in patients. This report emphasizes the importance of asepsis when working with animals with long-term intravascular catheters. We suggest that monitoring for this complication, e.g., by means of catheter cultures at the time of removal, should routinely be part of protocols for animal experiments using long-term intravascular catheters.     

Acinetobacter species as a cause of catheter-related infections

In recent years, Acinetobacter species have emerged as clinically important pathogens. Though these organisms are widely prevalent in nature, most human infections are hospital-acquired. Acinetobacter baumannii is the predominant species. Nosocomial Acinetobacter baumannii infections such as respiratory tract infections, urinary tract infections, meningitis following neurosurgical procedures, and bacteremia mainly affect patients with severe underlying disease in the ICU and often, in the setting of nosocomial outbreak. The occurrence of multiresistant strains often limits therapeutic options. A substantial part of Acinetobacter baumannii bacteremia cases represent catheter-related infections that usually carry a favorable prognosis. Acinetobacter species other than Acinetobacter baumannii are less frequently reported as a cause of infection in humans. Bacteremia due to these organisms is mostly sporadic and almost exclusively related to intravascular devices. The underlying diseases are often less severe than those of patients affected by Acinetobacter baumannii infections. The clinical course is usually benign and the infection responds readily to catheter removal irrespective of the appropriateness of antimicrobial therapy.     

Epidemiology of nosocomial infections

The frequency of nosocomial infections lies between 5 and 10%, and varies according to the type of hospital and service. Age, underlying disease invasive devices (such as catheters) or procedures are the main risk factors. Common nosocomial infections are urinary tract infections, pneumonia, surgical site infections, bacteremia/septicemia and intravascular catheter-related infections. Gram positive cocci and gram negative bacilli account for one third and two thirds of microorganisms respectively, Staphylococcus aureus being frequently resistant to antibiotics. Prevention is based on a better control of infection risk related to the use of invasive devices.     

An outbreak of vancomycin-resistant Enterococcus faecium in liver transplant recipients

Vancomycin-resistant Enterococcus faecium (VREF) has become a significant nosocomial pathogen for immunosuppressed patients. During a 5-month period in 1993, 8 cases of invasive infection with VREF (7 with bacteremia) were identified in liver transplant recipients, half of whom were adults. Epidemiology and microbiology studies were designed to identify the source and to determine the risk factors for this infection. Overall mortality was 50% (3 adults and 1 child). Mortality in bacteremic patients was 57%. A case-control study showed that cases were more likely to have been treated with a third-generation cephalosporin or vancomycin and to have undergone more than four biliary tract procedures. Environmental surveillance cultures yielded only one VREF isolate from a rectal temperature probe, but this device was used in only 2 of the cases. Cultures from all surgery and radiology suites were negative. All VREF isolates were genotyped by contour-clamped homogenous electric field electrophoresis of chromosomal DNA restriction fragments. These studies showed that a single clone was responsible for the outbreak, although other clones could be detected in the hospital. After implementing strict contact isolation on the liver transplant unit, only 1 additional patient with VREF was identified during this outbreak. In conclusion, it was found that antibiotic use and biliary tract manipulation were risk factors for developing invasive infections with VREF after liver transplantation. Optimal treatment is still unclear but most likely includes a combination of two or more antibiotics. Prompt institution of infection control measures can preclude rapid spread of this nosocomial pathogen.     

Generation of chromosome fragment specific bovine DNA sequences by microdissection and DOP-PCR

Trends in causative organisms and sources of infection were studied in a series of 288 episodes of bacteremia in neutropenic cancer patients observed in a single institution from 1986 to 1993. The incidence of bacteremia increased significantly from 20 episodes per 1000 admissions in 1986 to 50 episodes per 1000 admissions in 1993 (p = 0.00001). Over the study period, a continuous increment in gram-positive bacteremia, which reached 81% of episodes in 1993 (p = 0.000001), was observed. Conversely, the incidence of gram-negative bacteremia remained stable. Coagulase-negative staphylococci and viridans group streptococci were the most commonly isolated pathogens. Bacteremia caused by coagulase-negative staphylococci increased from 3 episodes per 1000 admissions to 19 episodes per 1000 admissions (p = 0.0001), and viridans group streptococci bacteremia increased from 0 episodes per 1000 admissions to 19 episodes per 1000 admissions (p = 0.000001). The upward trend in gram-positive bacteremia appeared to be related to a significant increase in both intravascular catheters (p = 0.003) and oral mucositis (p = 0.003) as sources of infection. Specific strategies to prevent chemotherapy-induced mucositis and catheter-related bacteremia merit further investigations.     

Microbiological examinations and in-vitro testing of different antibiotics in therapeutic endoscopy of the biliary system

BACKGROUND AND STUDY AIMS: Prior to endoscopic therapeutic procedures, no antibiotic prophylaxis is administered routinely. Because of the reported incidence of infectious complications, which may reach up to 10%, a prospective study was undertaken to investigate the effects of a prophylactic dose of cefuroxime on the incidence of bacteremia and clinical signs of infection, but no significant effects could be demonstrated. In addition to this published work, blood and bile cultures obtained in this trial were also investigated, and the in-vitro susceptibility to several antibiotics was tested in order to recommend the appropriate substances. PATIENTS AND METHODS: Ninety-nine consecutive patients (51 men, 48 women; mean age 61.4 +/- 17 years) with biliary obstruction who underwent an endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography with drainage (PTCD) were included. Sequential blood cultures were taken before and up to 60 minutes after the endoscopic intervention. Bile cultures were obtained in 56 patients with biliary drainage. Aerobic and anaerobic cultures were prepared from all obtained specimens and the isolated organisms were identified. In the case of positive cultures, an in-vitro resistance test for 15 different antibiotics was performed. RESULTS: The incidence of bacteremia was 11.1% (n = 11), and 16 bacteria were isolated. Twelve different microorganisms were detected, with Escherichia coli found in four cases. From 41 positive out of 56 prepared bile cultures (73.2%), 91 isolates were found with 25 different species. A single agent was detected in eight cases (19.5%), while a mixed growth, with pathogens ranging from two to six species, was found in 33 cases (80.5%). The seven most frequently isolated germs were E. coli and Enterococcus (each n = 19), Klebsiella (n = 10), Streptococcus viridans (n = 9), Staphylococcus epidermidis (n = 5), Morganella morganii (n = 4), and Bacteroides fragilis (n = 3), representing 76% of all agents. Examination for fungal infection revealed positive cultures of Candida albicans in 16.1% of bile cultures (nine of 56). Interestingly, the use of proton-pump inhibitors (PPIs), with a consequent rise in the gastric pH value, led to an increase in the rate of bacteremia to 26.2% (five of 19) compared to the other patients not on PPIs (n = 80), who developed bacteremia in only six cases (7.5%; p = 0.02). In-vitro testing of different antibiotics was carried out in 73 isolates. Imipenem showed the best antimicrobial activity (98.4%), followed by trimethoprim and sulfamethoxazole (90%), amoxicillin plus clavulanic acid (87.3%), vancomycin (82.4%), and ofloxacin (76.9%). CONCLUSIONS: Escherichia coli was found to be the pathogen most frequently detected in blood and bile following endoscopic interventions in the biliary tract. Enterococci, Klebsiella and Streptococcus viridans were found in bile cultures with an incidence exceeding 10%. In view of the in-vitro test results, possible side effects, and contraindications, amoxicillin plus beta-lactamase inhibitors or quinolones are considered to be suitable antibiotics for the prophylaxis of biliary infections.     

Molecular markers for differentiation of multiresistant Klebsiella pneumoniae isolates in a pediatric hospital

OBJECTIVE: To study the spread of extended-spectrum beta-lactamase-producing, but aminoglycoside-susceptible, Klebsiella pneumoniae strains in our hospital over an 8-month period, by using two genotypic markers. DESIGN: Ribotyping (using two endonucleases) and randomly amplified polymorphic DNA analysis (RAPD; using two different 10-mer primers) were applied to the epidemiological typing of clinical K pneumoniae isolates from stools, ileal fluid, or urine of hospitalized children. SETTING AND PATIENTS: The surgical intensive-care ward (S1: 9 patients, 17 isolates), surgical unit (S2: 2 patients, 2 isolates), and gastroenterology ward (GE: 1 patient, 1 isolate) of the Robert Debré Hospital of Paris, France. RESULTS: Ribotyping of the 20 clinical isolates, the type strain of the species, and two epidemiologically unrelated isolates with EcoRI and HindIII revealed 6 and 5 different patterns, respectively. Six ribotypes were identified by using these two enzymes. RAPD generated 6 distinct patterns, in complete agreement with ribotyping. Our genotypic results showed that 11 patients from wards S1, S2, and GE harbored genotypically related strains, suggesting nosocomial transmission and cross-colonization between and within the three wards. CONCLUSIONS: Ribotyping and RAPD appear to be reliable methods for distinguishing K pneumoniae strains. The spread of one strain of K pneumoniae in different units of our hospital was demonstrated by both methods. However, RAPD has the advantage of simplicity and rapidity conferred by polymerase chain reaction.     

Clinical significance of the isolation of rapidly growing mycobacteria

BACKGROUND: To assess the clinical significance of the isolates of rapid-growing mycobacteria in a Universitary hospital from Madrid (Spain). PATIENTS AND METHODS: Review of medical records from patients with isolates of rapid-growing mycobacteria identified between 1979 and 1996 in the Microbiology department of the Fundación Jiménèz Díaz (Madrid, Spain). RESULTS: Rapid-growing mycobacteria were isolated from 28 patients during the study period (13 M. chelonae, 10 M. fortuitum, 2 M. mucogenicum, 1 M. marinum, 1 M. smegmatis and 1 M. flavascens). Clinical records of 26 patients were reviewed, being the isolate significative in 10 cases (5 soft tissue infections, 2 peritonitis in patients undergoing Continuous Ambulatory Peritoneal Dialysis [CAPD], 1 urinary tract infection, 1 osteomyelitis and 1 catheter-related soft-tissue infection). No patient was HIV+. All infections cured except 2 of them (the urinary tract infection and the osteomyelitis). Catheter withdrawal was needed in 3 cases (peritonitis in CAPD and catheter-related soft-tissue infection), apart from proper antimicrobial therapy. CONCLUSION: The most frequent rapid-growing mycobacteria isolated were those of the M. fortuitum complex. In our experience, isolation of rapid-growing mycobacteria from skin and soft-tissue samples was usually clinically significant, while isolates from respiratory tract, gut and blood cultures are always nonsignificant.     

Indwelling device-related bacteremia caused by serum-susceptible Campylobacter coli

Two isolates of serum-susceptible Campylobacter coli were recovered in a 7-day interval from blood from a patient with hepatocellular carcinoma and liver cirrhosis whose peritoneal-caval (Denver's) shunt malfunctioned. Identical random amplified polymorphic DNA fingerprints, cellular fatty acid chromatograms, and antibiograms of the two isolates indicate that C. coli has the ability to cause catheter-related bacteremia following its colonization of the catheter.     

Meningitis caused by Streptococcus bovis

Streptococcus bovis was isolated from the CSF of a 66-year-old man with meningitis. His clinical appearance was unusual in that he lacked typical signs and symptoms of pyogenic meningitis. Streptococcus bovis was also recovered from his blood, which suggested that bacterial endocarditis was the source of his CNS infection. He was cured after four weeks of therapy with intravenous penicillin G potassium. This is the fourth reported case of meningitis caused by S bovis. The previous three patients also had endocarditis caused by S bovis. Because of the reported propensity of S bovis to infect heart valves and the frequent association of S bovis bacteremia with malignant gastrointestinal (GI) tract tumors, recovery of this organism form CSF should prompt a search for bacterial endocarditis and occult GI cancer.     

Moraxella catarrhalis: clinical significance, antimicrobial susceptibility and BRO beta-lactamases

Moraxella catarrhalis is an important pathogen of humans. It is a common cause of respiratory infections, particularly otitis media in children and lower respiratory tract infections in the elderly. Colonisation of the upper respiratory tract appears to be associated with infection in many cases, although this association is not well understood. Nosocomial transmission is being increasingly documented and the emergence of this organism as a cause of bacteremia is of concern. The widespread production of a beta-lactamase enzyme renders Moraxella catarrhalis resistant to the penicillins. Cephalosporins and beta-lactamase inhibitor combinations are effective for treatment of beta-lactamase producers, and the organism remains nearly universally susceptible to the macrolides, fluoroquinolones, tetracyclines and the combination of trimethoprim and sulfamethoxazole. Two major beta-lactamase forms, BRO-1 and BRO-2, have been described on the basis of their isoelectric focusing patterns. The BRO-1 enzyme is found in the majority of beta-lactamase-producing isolates and confers a higher level of resistance to strains than BRO-2. The BRO enzymes are membrane associated and their production appears to be mediated by chromosomal determinants which are transmissible by an unknown mechanism. The origin of these novel proteins is unknown.