[What is the significance of extended spectrum betalactamases in clinical practice?]. / Que signifie "bêtalactamases à spectre élargi" en pratique?

Extended spectrum betalactamases (ESBL) confer resistance to most commonly used betalactam antibiotics. Their emergence in Gram negative bacteria was observed after the widespread use of cephalosporins and quinolones. They can cause severe infections in the hospital as well as in the community. Carbapenems remain the first choice of treatment for these infections. Appropriate use of antibiotics could decrease the spread of ESBLs.

Molecular epidemiology of predominant clones and sporadic strains of methicillin resistant Staphylococcus aureus in Switzerland and comparison with European epidemic clones.

OBJECTIVE: To assess the molecular epidemiology and risk factors of predominant clones and sporadic strains of methicillin-resistant Staphylococcus aureus (MRSA) in Swiss hospitals and to compare them with European strains of epidemic clones. MATERIAL AND METHODS: One-year national survey of MRSA cases. Analysis of epidemiological and molecular typing data (PFGE) of MRSA strains. RESULTS: In 1997, 385 cases of MRSA were recorded in the five Swiss university hospitals and in 47 community hospitals. Half of the cases were found in Geneva hospitals where MRSA was already known to be endemic. Molecular typing of 288 isolates (one per case) showed that 186 (65%) belong to four predominant clones, three of which were mostly present in Geneva hospitals. In contrast, the fourth clone (85 cases) was found in 23 hospitals (in one to 16 cases per hospital). The remaining 35% of the strains were clustered into 62 pulsed field gel electrophoresis types. They accounted for one to five patients per hospital and were defined as sporadic. Multivariate analysis revealed no independent risk factors for harboring a predominant versus a sporadic strain, except that transfer from a foreign hospital increases the risk of harboring a sporadic strain (OR, 42; 95% CI, 5-360). CONCLUSION: While cases with predominant clones were due to the local spread of these clones, most sporadic cases appear to be due to the continuous introduction of new strains into the country. With the exception of a transfer from a hospital outside Switzerland, no difference in the clinical or epidemiological characteristics was observed between patients harboring a predominant clone and those with a sporadic strain.

Bronchopneumonia and oral health in hospitalized older patients. A pilot study.

AIMS: To correlate microbial findings obtained by bronchoalveolar lavage in pneumonia patients with the clinical situation of the oral cavity. METHOD: Quantitative aerobic and anaerobic cultures were carried out in 150 ml samples of bronchoalveolar lavage (BAL) obtained by means of an endoscope (Video Endoscope Pentax) inserted per os in the infected bronchus. MATERIAL: Twenty consecutive patients with a tentative clinical diagnosis of bronchopneumonia in whom BAL was carried out for diagnostic purposes. A clinical evaluation of the oral health status (oral hygiene, caries, periodontal diseases) was subsequently carried out. RESULTS: In seven edentulous subjects wearing complete dentures the culture of anaerobic microorganisms was negative or yielding less than 100 cfu/ml BAL. Two patients yielded high counts of S. aureus and one high counts of P. aeruginosa. In the 13 subjects with natural teeth left one showed high counts of Veillonella spp. (anaerobic) + P. aeruginosa, one high counts of Veillonella spp. + S. aureus, one high counts of P. aeruginosa + S. aureus and one high counts of E. coli. These four subjects showed poor oral hygiene, periodontal pockets and a BAL microflora consistent with periodontal pathology. CONCLUSION: The results of this pilot study suggest that microorganisms of denture plaque or associated with periodontal diseases may give rise to aspiration pneumonia in susceptible individuals.

Influence of previous exposure to antibiotic therapy on the susceptibility pattern of Pseudomonas aeruginosa bacteremic isolates.

Many patients who present with Pseudomonas aeruginosa bacteremia have been previously exposed to antibiotics. To assess whether resistance of bacteremic strains to antipseudomonal antibiotics (piperacillin, ceftazidime, imipenem, ciprofloxacin, or aminoglycosides) is associated with previous exposure to these drugs, a case-control study including 267 cases of P. aeruginosa bacteremia was conducted. Twenty-five percent of the episodes had been preceded by the exposure to an antipseudomonal antibiotic. Eighty-one strains were resistant to at least 1 antibiotic; 186 were susceptible to all drugs. Via univariate analysis, the risks of resistance to ceftazidime and imipenem were found to be significantly associated with previous receipt of these agents. Using multivariate analysis, exposure to any antipseudomonal antibiotic as a monotherapy was found to be associated with an increased risk of subsequent resistance to itself (odds ratio, 2.5; P=.006). Therefore, clinicians should avoid readministering previously prescribed antibiotics when initiating empiric therapies for possible P. aeruginosa bacteremia, especially when they have been given as monotherapies.

Combined screening for Chlamydia trachomatis and squamous intra-epithelial lesions using a single liquid-based cervical sample.

BACKGROUND: Cervicitis is believed to alter cytological interpretation and could compromise a combined screening for Chlamydia trachomatis (CT) cervicitis and squamous intra-epithelial lesions (SIL). Liquid-based cytological methods have been shown to limit obscuring factors and permit the detection of infectious agents by DNA amplification techniques. The aim of this study was to evaluate a combined screening for SIL and CT cervicitis with a single liquid-based cervical sample. METHODS: Two cervical samples were obtained from each of 590 women considered at high risk for CT. The modified Ligase chain reaction (LCR) procedure for CT detection using specimens collected in the AutoCyte's preservative fluid was compared with the conventional Abbott LCx method using cervical swabs. We have also compared the percentage of inflammatory specimens and adequacy of cellular material in the populations of CT+ and CT- women. RESULTS: The results show total agreement for 588 of 590 cervical samples using the two LCR protocols (Kappa = 0.96; 95% confidence interval: 0.91-1.00). The quality of cervical cytology was not compromised by CT cervicitis. CONCLUSIONS: We demonstrated the feasibility of combined screening for CT and SIL with a single liquid-based cervical sample.

Role of nasopharyngeal culture in antibiotic prescription for patients with common cold or acute sinusitis.

The aim of the present study was to assess the hypothesis that, when present in nasopharyngeal secretions, Streptococcus pneumoniae. Haemophilus influenzae, and Moraxella catarrhalis play a pathogenic role early in the course of an upper respiratory tract infection. Adults with a clinical diagnosis of acute sinusitis or common cold were enrolled. Participants were randomly assigned in a double-blind manner to receive azithromycin 500 mg daily or placebo for 3 days. The effect of treatment on symptom evolution in the predefined subset of patients with Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis in their nasopharyngeal secretions was assessed. Of 265 patients enrolled, 132 received placebo and 133 azithromycin. Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis was identified in nasopharyngeal secretions of 77 patients (29%). In this predefined subgroup of patients with Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis, resolution of symptoms by day 7 occurred in 73% of those treated with azithromycin compared with 47% of those who received placebo (P=0.007). The median time before resolution of symptoms was 5 days in the azithromycin group compared to 7 days in the placebo group. Respiratory complications requiring antibiotic treatment occurred in 19% of patients in the placebo group and in 3% of the azithromycin group (P=0.025). In the remaining 188 patients without Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis, resolution of symptoms by day 7 was similar in both groups (69% in the placebo group vs. 64% in the azithromycin group [P=0.75]). Antibiotic treatment is of clinical benefit for patients with acute sinusitis or common cold when Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis is present in nasopharyngeal secretions. This observation provides new insights into the pathogenic role of these bacteria in the early stage of the common cold.

Choosing a strategy to prevent neonatal early-onset group B streptococcal sepsis: economic evaluation.

OBJECTIVE: To determine the most appropriate strategy to prevent neonatal streptococcal sepsis in a setting with a low incidence of the disease. DESIGN: Decision analysis and economic evaluation. SETTING: Geneva University Hospitals, Switzerland. POPULATION: Pregnant women at 35-37 weeks of gestation and in labour. METHODS: Local data and data from the literature were used in a decision analysis to compare the current policy of antibiotic administration at Geneva University Hospitals with the recommended preventive strategies. MAIN OUTCOME MEASURES: Number of episodes of sepsis averted; cost and number needed to treat to prevent one episode of sepsis; and proportion of women receiving antibiotics during labour. RESULTS: Compared with the current policy, the risk factors strategy would prevent 69 streptococcal sepsis per million deliveries and the screening strategy would prevent 102 cases of sepsis per million deliveries. Cost per averted sepsis case would be 60 pounds, 700 and 473 pounds, 600, respectively. The number needed to treat to prevent one sepsis would be 1,087 with a risk factors strategy and 1,029 with a screening strategy. Preventive strategies would increase the proportion of women receiving antibiotics during labour from 6% with the current policy, to 13.5% and 16.5% respectively. CONCLUSIONS: Preventive strategies are more effective than the current policy, but imply increased hospital costs and a notable increase in the proportion of women receiving antibiotics during labour, which may be unjustified in a low incidence setting.

[Colonization by Ureaplasma urealyticum and chronic lung disease in premature newborn infants under 32 weeks of gestation]. / Colonisation par Ureaplasma urealyticum et maladie pulmonaire chronique chez les nouveau-nés prématurés de moins de 32 semaines de gestation.

UNLABELLED: Colonization of the respiratory tract of premature newborn infants by genital mycoplasma is suspected to be associated with chronic lung disease. METHODS AND PATIENTS: We prospectively determined the prevalence of genital mycoplasma colonization with nasopharyngeal or endotracheal culture in preterm neonates younger than 32 weeks gestation and its possible association with the development of chronic lung disease in a prospective study. RESULTS: Fifty-nine infants were enrolled and 11 (19%) were colonized with Ureaplasma urealyticum. In the subgroup of 45 ventilated infants, seven of seven U. urealyticum-positive infants developed chronic pulmonary disease versus ten of 38 (26%) of U. urealyticum-negative infants (relative risk [RR] = 3.8; 95% confidence interval [CI] 2.2 to 6.5, P < 0.001). U. urealyticum-colonized infants had a lower median birth weight (760 vs 1,083 g, P = 0.04), a lower gestational age (26 vs 28 weeks, P = 0.03), and a higher incidence of symptomatic patent ductus arteriosus (P = 0.03). These potential confounding factors may partially explain the association between U. urealyticum and chronic pulmonary disease. However, this association remained statistically significant when the analysis was restricted to infants with birth weight of 1,000 g or less (RR = 2.3; 95% CI 1.3 to 4, P = 0.02) or to infants with a patent ductus arteriosus (RR = 2; 95% CI 1.3 to 3.1, P = 0.02). CONCLUSION: Colonization with U. urealyticum in ventilated preterm neonates younger than 32 weeks gestation is a significant risk factor of developing chronic pulmonary disease.

Risk factors for persistent carriage of methicillin-resistant Staphylococcus aureus.

We determined risk factors associated with persistent carriage of methicillin-resistant Staphylococcus aureus (MRSA) among 102 patients enrolled in a double-blind, placebo-controlled trial of nasally administered mupirocin ointment. MRSA decolonization was unsuccessful in 77 (79%) of 98 patients who met the criteria for evaluation. By univariate analysis, 4 variables were found to be associated with persistent MRSA colonization (P < .1 for all 4): absence of mupirocin treatment, previous fluoroquinolone therapy, > or = 2 MRSA-positive body sites, and low-level mupirocin resistance. After multivariable Cox proportional hazards modeling, the presence of > or = 2 positive body sites (adjusted hazard ratio [AHR], 1.7; 95% confidence interval [CI], 1.0-2.9) and previous receipt of a fluoroquinolone (AHR, 1.8; 95% CI, 1.0-3.3) were independently associated with MRSA persistence, whereas nasal mupirocin tended to confer protection (AHR, 0.6; 95% CI, 0.4-1.0). Low-level mupirocin resistance was observed in 9 genotypically different MRSA strains and was not independently associated with chronic MRSA carriage (AHR, 1.5; 95% CI, 0.9-2.5). Our findings suggest that multisite MRSA carriage and previous receipt of a fluoroquinolone are independent risk factors for persistent MRSA colonization.

Evaluation of the Bactec 960 automated nonradiometric system for isolation of mycobacteria from clinical specimens.

The Bactec MGIT 960 system (Becton Dickinson, USA), designed for the culture of mycobacteria, was compared with the Bactec 460 instrument and culture on two solid egg-based media using a total of 1024 clinical specimens. Mycobacteria could be identified from 99 (9.7%) specimens, 89 (90%) of which were identified by the Bactec 960 system, 90 (91%) by the Bactec 460 system, and 82 (83%) by culture on the two egg-based media. The Bactec 960 cultures became positive an average of 16.7 days after specimen collection, the Bactec 460 cultures 14.9 days after collection, and the cultures on egg-based media 26.2 days after collection. The Bactec 960 is a compact and highly automated nonradiometric system that may replace the Bactec 460 system.

Effect of delayed infection control measures on a hospital outbreak of methicillin-resistant Staphylococcus aureus.

All patients positive for methicillin-resistant Staphylococcus aureus (MRSA) at the University Hospitals of Geneva, Switzerland, between 1989 and 1997 (N = 1771) were included in a cohort study to evaluate the consequences of delayed containment of a hospital-wide outbreak occurring during a 4-year absence of MRSA control measures. The effects of efforts to control both the MRSA reservoir and the number of bacteraemic patients were assessed. Intensive infection control measures were initiated in 1993 and included patient screening, on-site surveillance, contact isolation, a computerized alert system, and hospital-wide promotion of hand hygiene. An increase in the rate of new MRSA-infected or -colonized patients was observed between 1989 and 1994 (from 0.05 to 0.60 cases per 100 admissions), which subsequently decreased to 0.24 cases in 1997 (P<0.001). However, the proportion of laboratory-documented methicillin-resistant isolates among all S. aureus showed little variation in the years from 1993 onwards (range, 19-24%), reflecting the result of an increase in the number of screening cultures. The annual number of patients with MRSA bacteraemia strongly correlated with the hospital-wide prevalence of MRSA patients (R(2)= 0.60; P = 0.01) and the rate of new MRSA patients (R(2)= 0.97; P<0.001). Consequently, the attack rate of nosocomial MRSA bacteraemia served as an excellent marker for the MRSA patient reservoir. In conclusion, despite delayed implementation, infection control measures had a substantial impact on both the reservoir of MRSA patients and the attack rate of MRSA bacteraemia.

Three cases of cutaneous sarcoidosis: search for bacterial agent by the 16S RNA gene analysis and treatment with antibiotics.

BACKGROUND: The aetiology of sarcoidosis remains controversial. An infectious origin is often discussed, but only anti-inflammatory or immunosuppressive treatment is recommended. OBJECTIVES: To investigate the hypothesis of bacterial origin by treating cutaneous sarcoidosis with antibiotics. METHODS: Patients with chronic cutaneous sarcoidosis, unresponsive to the usual treatment and not requiring systemic corticotherapy, were given combined antibiotherapy for 6 months. Search for bacterial DNA by amplification and sequencing of the 16S ribosomal RNA gene in skin biopsies of lesions before and after antibiotherapy was done. RESULTS: Three patients received a combined treatment with clarithromycin 1 g/day and ciprofloxacin 1 g/day. No clinical changes occurred in 2 cases and transient worsening in 1. Amplification for bacterial DNA was positive in all skin biopsies. The sequencing of this DNA could not identify a unique bacterial species. CONCLUSION: No evident bacterial origin could be demonstrated; however, this approach should be extended to more patients.

[Symptoms and clinical and radiological signs predicting the bacterial origin of acute rhinosinusitis]. / Symptômes, signes cliniques et radiologiques prédictifs de l'origine bactérienne des rhino-sinusites aiguës.

A minority of patients with common cold and upper respiratory tract infections have a bacterial infection and may benefit from antibiotic therapy. The present analysis set out to determine whether there were clinical symptoms or signs which could help the clinician to identify a subset of patients with moderate forms of acute rhinosinusitis who are infected with pathogenic bacteria. Detailed clinical history and medical examination were obtained from 265 patients (mean age 35 years, 138 females and 127 males) presenting symptoms of upper respiratory tract infections but no fever above 38 degrees C. The presence of three pathogenic bacteria (S. pneumoniae, H. influenzae or M. catarrhalis) was determined in all patients by culture of nasopharyngeal secretions. Aggravating factors for severity of rhinosinusitis, such as severe nasal obstruction, inferior and/or middle turbinate hypertrophy, oedema of the middle meatus mucosa and septal defects, were not associated with the presence of bacteria. Pathogenic bacteria were found in 77 patients (29%). The clinical signs and symptoms which were significantly associated in a multivariate model with the presence of bacteria included facial pain (p < 0.003), coloured nasal discharge (p < 0.003) and radiological maxillary sinusitis (complete opacity, air-fluid level or mucosal thickening greater than 10 mm) (p < 0.002). This, the best predictive model, had a sensitivity of 69% and a specificity of 64% and therefore could not be used either as a screening tool or as a diagnostic criterion for bacterial rhinosinusitis. We conclude that signs and symptoms of acute rhinosinusitis in patients with a mild to moderate clinical presentation are poor predictors of the presence of bacteria. In agreement with previous studies, culture of nasopharyngeal secretions may identify patients who would benefit from antibiotic treatment. Thus, antibiotic therapy should not be prescribed in the absence of bacteriological evidence.

In vitro activity of quinupristin/dalfopristin in comparison with five antibiotics against worldwide clinical isolates of staphylococci.

OBJECTIVE: To evaluate the in vitro activity of quinupristin/dalfopristin (Q/D), a streptogramin combination, in comparison with five antibiotics against worldwide clinical isolates of staphylococci. METHODS: A multicenter in vitro study was performed using the E test during a period of 3 months (April to June) in 1997 on fresh, clinically significant, non repetitive strains of staphylococci from patients hospitalized in 23 different hospitals in 18 countries tested. RESULTS: A total of 2132 staphylococcal isolates including methicillin resistant (MR), methicillin susceptible (MS) S. aureus (1003 MS, 462 MR), S. epidermidis (169 MS, 251 MR), S. haemolyticus (28 MS, 46 MR), S. hominis (28 MS, 16 MR), and coagulase negative staphylococci (86 MS, 43 MR) were analyzed. Q/D was highly active against all species tested. MIC90 (mg/L) ranged from 0.5 to 2 depending on the species. Strains had MIC < or = 1 mg/L in 97.6%. For S. aureus, S. epidermidis, S. hominis and other coagulase-negative staphylococci no differences in MIC90 were observed for MS or MR. One dilution difference was observed for S. haemolyticus, which overall was the less susceptible species. Erythromycin resistance was observed among 57- 87% of MR-strains and was lower among MS-strains (18-56%). Erythromycin resistance had no or little influence on MIC of Q/D. In comparison to vancomycin, Q/D was two to four times more active. CONCLUSIONS: The streptogramin combination Q/D showed an excellent in vitro activity against all staphylococcal species tested regardless of the resistance pattern to other drug classes, particularly resistance to methicillin. Q/D was two to four times more active than vancomycin and MIC values varied from 0.5-2 according to the species. The synergy of Q/D was well conserved in macrolide-resistant strains.

Group A beta-hemolytic streptococcus meningitis: clinical and microbiological features of nine cases.

Group A beta-hemolytic streptococcus (GAS) meningitis is a rare disease in adults. We conducted a retrospective study to describe clinical and microbiological features of nine cases of GAS meningitis in Switzerland. Of nine patients, six had neurosurgical conditions, and five had upper respiratory tract infections. Eight cases were community-acquired. The outcome of GAS meningitis was favorable; only one patient died of neurosurgical complications. No patient presented with toxic shock syndrome. Serotyping failed to reveal a dominant strain, and genotyping revealed that two strains carried the gene encoding the streptococcal pyrogenic exotoxin C and that one strain carried the gene encoding the streptococcal pyrogenic exotoxin A. Our observations suggest that GAS meningitis in adults is associated with neurosurgical conditions and/or an upper respiratory tract infection.

Impact and pattern of gram-negative bacteraemia during 6 y at a large university hospital.

In order to characterize the impact and pattern of Gram-negative bacteraemia (GNB) at a Swiss University hospital and to assess the effect of multi-resistance on mortality, we conducted a 6-y retrospective cohort study using linear regression and multivariate Cox-proportional hazard analysis. 1766 patients had 1835 episodes of GNB; 61% were community-acquired. The incidence of GNB increased linearly (r2 = 0.90, p = 0.014) from 7.07 episodes to 8.32 episodes per 1000 admissions, but this trend was no longer significant after adjustment for the number of blood cultures drawn/y. The in-hospital mortality for patients with GNB decreased from 20% in 1989 to 16% in 1994 (r2 = 0.94, p = 0.005). The risk ratio for death remained unchanged over the study period and was 7-fold higher for patients with GNB than for patients without GNB. Factors independently associated with an increased hazard of death after GNB were: severity of illness as measured by exposure to intensive care (hazard ratio [HR], 1.5); age = 66-79 y (HR 1.8); GNB due to Klebsiella spp. (HR 1.7) or Pseudomonas aeruginosa (HR 1.6); and polymicrobial infection (HR 1.6). Multi-resistance was not associated with an increased risk of death (HR 1.0). Although the crude mortality of GNB decreased, the population-attributable risk ratio for death remained significant. These data suggest the absence of a major impact of multi-resistant GNB on patient mortality.

Antimicrobial susceptibility of bacterial pathogens in the oropharynx of healthy children.

In a study to determine the prevalence and antimicrobial susceptibility of bacterial pathogens in the oropharynx of healthy children, throat swabs obtained from 1765 children were cultured and the organisms recovered tested by the disk diffusion method and the E test. Six hundred ninety-one children (39.1%) harbored Haemophilus influenzae, 112 (6.3%) Streptococcus pyogenes, 73 (4.1%) Moraxella catarrhalis, 52 (2.9%) Streptococcus pneumoniae, and 50 (2.8%) Neisseria meningitidis in their oropharynx. The rate of penicillin resistance was 2%, 0%, and 12%, respectively, for Streptococcus pneumoniae, Streptococcus pyogenes, and Neisseria meningitidis. Ampicillin resistance was observed in 8.6% of Haemophilus influenzae strains and 78% of Moraxella catarrhalis strains and was associated with the presence of beta-lactamase, except in one strain of Haemophilus influenzae. Five (4.4%) isolates of Streptococcus pyogenes were resistant to macrolides. The low level of resistance observed in this area contrasts with the high rates reported in the literature.

Randomized, placebo-controlled, double-blind trial to evaluate the efficacy of mupirocin for eradicating carriage of methicillin-resistant Staphylococcus aureus.

Mupirocin has been widely used for the clearance of nasal methicillin-resistant Staphylococcus aureus (MRSA) carriage during outbreaks, but no placebo-controlled trial has evaluated its value for eradicating MRSA carriage at multiple body sites in settings where MRSA is not epidemic. In a 1,500-bed teaching hospital with endemic MRSA, 102 patients colonized with MRSA were randomized into a double-blind, placebo-controlled trial and treated with either mupirocin (group M) or placebo (group P) applied to the anterior nares for 5 days; both groups used chlorhexidine soap for body washing. Follow-up screening, susceptibility testing, and genotyping were performed to evaluate treatment success, mupirocin or chlorhexidine resistance, and exogenous recolonization. At baseline, MRSA carriage was 60% in the nares, 38% in the groin, and 62% in other sites (skin lesions, urine). The MRSA eradication rate (all body sites) was 25% in group M (12 of 48 patients), compared to 18% in group P (9 of 50 patients; relative risk [RR], 0.72; 95% confidence interval [CI95], 0.33 to 1.55). At the end of follow-up, 44% of patients (19 of 43) were free of nasal MRSA in group M, compared to 23% (11 of 44) in group P (RR, 0.57; CI95, 0.31 to 1.04). Ten patients developed MRSA infections (three in group M and seven in group P). One mupirocin treatment failure was due to exogenous MRSA recolonization. No MRSA isolate showed chlorhexidine resistance or high-level mupirocin resistance; however, we observed an association (P = 0.003) between low-level mupirocin resistance at study entry (prevalence, 23%) and subsequent treatment failure in both study arms. These results suggest that nasal mupirocin is only marginally effective in the eradication of multisite MRSA carriage in a setting where MRSA is endemic.

Assessment of use of the COBAS AMPLICOR system with BACTEC 12B cultures for rapid detection of frequently identified mycobacteria.

The use of the COBAS AMPLICOR System (Roche Molecular Diagnostics, Basel, Switzerland), the only automated system for PCR testing, was evaluated for a rapid identification of mycobacteria with positive BACTEC 12B cultures. Two hundred ninety-six specimens with a growth index of >/=30 were analyzed for the presence of Mycobacterium tuberculosis complex, Mycobacterium avium, and Mycobacterium intracellulare. Compared to traditional methods and provided that samples with PCR inhibition are retested at a 1:10 dilution, the sensitivity and specificity of the COBAS AMPLICOR System with BACTEC 12B cultures were 100 and 98%, respectively. The COBAS AMPLICOR method is rapid and reliable for identifying the most common mycobacteria in cultures.