Cross-transmission Is Not the Source of New Mycobacterium abscessus Infections in a Multicenter Cohort of Cystic Fibrosis Patients.

BACKGROUND: Mycobacterium abscessus is an extensively drug-resistant pathogen that causes pulmonary disease, particularly in cystic fibrosis (CF) patients. Identifying direct patient-to-patient transmission of M. abscessus is critically important in directing an infection control policy for the management of risk in CF patients. A variety of clinical labs have used molecular epidemiology to investigate transmission. However, there is still conflicting evidence as to how M. abscessus is acquired and whether cross-transmission occurs. Recently, labs have applied whole-genome sequencing (WGS) to investigate this further and, in this study, we investigated whether WGS can reliably identify cross-transmission in M. abscessus. METHODS: We retrospectively sequenced the whole genomes of 145 M. abscessus isolates from 62 patients, seen at 4 hospitals in 2 countries over 16 years. RESULTS: We have shown that a comparison of a fixed number of core single nucleotide variants alone cannot be used to infer cross-transmission in M. abscessus but does provide enough information to replace multiple existing molecular assays. We detected 1 episode of possible direct patient-to-patient transmission in a sibling pair. We found that patients acquired unique M. abscessus strains even after spending considerable time on the same wards with other M. abscessus-positive patients. CONCLUSIONS: This novel analysis has demonstrated that the majority of patients in this study have not acquired M. abscessus through direct patient-to-patient transmission or a common reservoir. Tracking transmission using WGS will only realize its full potential with proper environmental screening, as well as patient sampling.

The Different Microbial Etiology of Prosthetic Joint Infections according to Route of Acquisition and Time after Prosthesis Implantation, Including the Role of Multidrug-Resistant Organisms.

The aim of our study was to characterize the etiology of prosthetic joint infections (PJIs)-including multidrug-resistant organisms (MDRO)-by category of infection. A multicenter study of 2544 patients with PJIs was performed. We analyzed the causative microorganisms according to the Tsukayama's scheme (early postoperative, late chronic, and acute hematogenous infections (EPI, LCI, AHI) and "positive intraoperative cultures" (PIC)). Non-hematogenous PJIs were also evaluated according to time since surgery: <1 month, 2-3 months, 4-12 months, >12 months. AHIs were mostly caused by Staphylococcus aureus (39.2%) and streptococci (30.2%). EPIs were characterized by a preponderance of virulent microorganisms (S. aureus, Gram-negative bacilli (GNB), enterococci), MDROs (24%) and polymicrobial infections (27.4%). Conversely, coagulase-negative staphylococci (CoNS) and Cutibacterium species were predominant in LCIs (54.5% and 6.1%, respectively) and PICs (57.1% and 15.1%). The percentage of MDROs isolated in EPIs was more than three times the percentage isolated in LCIs (7.8%) and more than twice the proportion found in AHI (10.9%). There was a significant decreasing linear trend over the four time intervals post-surgery for virulent microorganisms, MDROs, and polymicrobial infections, and a rising trend for CoNS, streptococci and Cutibacterium spp. The observed differences have important implications for the empirical antimicrobial treatment of PJIs.

Healthcare-Associated Mycobacterium bovis-Bacille Calmette-Guérin (BCG) Infection in Cancer Patients Without Prior BCG Instillation.

Background: Bacille Calmette-Guérin (BCG), an attenuated strain of Mycobacterium bovis, is widely used as adjunctive therapy for superficial bladder cancer. Intravesical administration of BCG has been associated with systemic infection. Disseminated infection due to M. bovis is otherwise uncommon. Methods: After identification of 3 patients with healthcare-associated BCG infection who had never received intravesical BCG administration, an epidemiologic study was performed. All patients with healthcare-associated BCG infection in the Barcelona tuberculosis (TB) program were reviewed from 1 January 2005 to 31 December 2015, searching for infections caused by M. bovis-BCG. Patients with healthcare-associated BCG infection who had not received intravesical BCG instillation were selected and the source of infection was investigated. Results: Nine oncology patients with infection caused by M. bovis-BCG were studied. All had permanent central venous catheters. Catheter maintenance was performed at 4 different outpatient clinics in the same room in which other patients underwent BCG instillations for bladder cancer without required biological precautions. All patients developed pulmonary TB, either alone or with extrapulmonary disease. Catheter-related infection was considered the mechanism of acquisition based on the epidemiologic association and positive catheter cultures for BCG in patients in whom mycobacterial cultures were performed. Conclusions: Physicians should be alerted to the possibility of TB due to nosocomially acquired, catheter-related infections with M. bovis-BCG in patients with indwelling catheters. This problem may be more common than expected in centers providing BCG therapy for bladder cancer without adequate precautions.

Characteristics and outcome of spontaneous bacterial meningitis in patients with cancer compared to patients without cancer.

In cancer patients, who are frequently immunocompromised, bacterial meningitis (BM) can be a severe complication, with a different presentation, etiology, and course, compared to patients without cancer. Our objective is to compare the characteristics and outcomes of BM in patients with and without cancer. A single-center, prospective observational cohort study, conducted between 1982 and 2012, in a tertiary university hospital in Barcelona (Spain). The main outcome measure is in-hospital mortality. We evaluated 659 episodes of BM; 97 (15%) had active cancer. Patients with malignancies were older (median 63 (interquartile range [IQR] 24) vs 52 [IQR 42] years, P < .001) and more often had a Charlson comorbidity score of ≥3 (51% vs 11%, P < .001). The classic meningitis triad (35% vs 50%, P = .05), fever (91% vs 96%, P = .03), neck stiffness (58% vs 78%, P < .001), headache (63% vs 77%) P = .003), and rash (7% vs 30%, P < .001) were less frequent. There was a longer interval between admission and antibiotic therapy (median 5 [IQR 14] vs 3 [IQR 6] hours, P < .001). Listeria meningitis was the commonest cause of BM (29%) and was more frequent in cancer than noncancer (8%, P < .001) patients, whereas meningococcal meningitis was much less frequent (4% vs 36%, P < .001). Overall mortality was higher in patients with cancer (31% vs 16%, P < .001), although cancer was not associated with an unfavorable outcome in the multivariate analysis (odds ratio 1.825, P = .07). Patients with meningitis and cancer are older and have more subtle clinical manifestations than patients without cancer. Listeria monocytogenes is the predominant pathogen and mortality is higher in cancer patients.

Spontaneous gram-negative bacillary meningitis in adult patients: characteristics and outcome.

BACKGROUND: Spontaneous meningitis caused by gram-negative bacilli in adult patients is uncommon and poorly characterized. Our objective is to describe and compare the characteristics and the outcome of adult patients with spontaneous gram-negative bacilli meningitis (GNBM) and spontaneous meningitis due to other pathogens. METHODS: Prospective single hospital-based observational cohort study conducted between 1982 and 2006 in a university tertiary hospital in Barcelona (Spain). The Main Outcome Measure: In-hospital mortality. RESULTS: Gram-negative bacilli meningitis was diagnosed in 40 (7%) of 544 episodes of spontaneous acute bacterial meningitis. The most common pathogens were Escherichia coli and Pseudomonas species. On admission, characteristics associated with spontaneous gram-negative bacilli meningitis by multivariate modeling were advanced age, history of cancer, nosocomial acquisition of infection, urinary tract infection as distant focus of infection, absence of rash, hypotension, and a high cerebrospinal fluid white-cell count. Nine (23%) episodes were acquired in the hospital and they were most commonly caused by Pseudomonas. The in-hospital mortality rate was 53%. The mortality rate was higher among patients with Gram-negative bacillary meningitis than among those with other bacterial meningitis and their risk of death was twenty times higher than among patients infected with Neisseria meningitidis (odds ratio 20.47; 95% confidence interval 4.03-103.93; p<0.001). CONCLUSIONS: Gram-negative bacilli cause 9% of spontaneous bacterial meningitis of known etiology in adults. Characteristics associated with GNBM include advanced age, history of cancer, nosocomial acquisition, and urinary tract infection as distant focus of infection. The mortality rate is higher among patients with gram-negative bacillary meningitis than among those with other bacterial meningitides.

Impaired fitness of Mycobacterium tuberculosis resistant isolates in a cell culture model of murine macrophages.

OBJECTIVES: We analysed the ability of Mycobacterium tuberculosis clinical isolates to penetrate and grow inside murine macrophages as a surrogate of fitness. METHODS: Thirty-five drug-resistant and 10 drug-susceptible M. tuberculosis isolates were studied in a murine macrophage model from the J774.2 cell line in a 6 day protocol, performing semi-quantitative counts in Middlebrook 7H11 medium. The mycobacterial penetration index (MPI) after infection and the mycobacterial growth ratio (MGR) inside the macrophages were determined to evaluate the fitness of isolates. RESULTS: Isolates with the katG S315T mutation and multidrug-resistant (MDR) isolates had a significantly lower MGR compared with drug-susceptible isolates. The MPI of the isolates with the katG S315T mutation showed a significant decrease compared with the MPI of those without this mutation. A trend to significantly lower values was also observed on comparing the MPI of the MDR isolates with that of the drug-susceptible isolates and the isolates resistant to isoniazid. CONCLUSIONS: The isoniazid-resistant and MDR isolates with mutations in the katG gene showed decreased multiplication inside murine macrophages, suggesting a lower fitness of M. tuberculosis with these resistance patterns.

A simple phenotypic method for differentiation between acquired and chromosomal AmpC beta-lactamases in Escherichia coli.

BACKGROUND: Screening methods for the detection of plasmid-mediated AmpC beta-lactamases are technically demanding. The purpose of this study was to assess screening methods for the detection of these enzymes in clinical isolates of Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. METHODS: Isolates were selected according to a resistance phenotype consistent with production of an AmpC-type beta-lactamase. Detection of acquired ampC genes was done with a multiplex ampC-PCR and sequencing. The phenotypic detection methods evaluated included visual examination of antibiogram plates to identify the presence of scattered colonies located near the edge of the inhibition halo of cefoxitin, cefotaxime, ceftazidime and aztreonam, and a double-disc synergy test using cloxacillin (500 mg) to inhibit AmpC enzymes. RESULTS: Seventy-seven isolates were selected from among 6,209 isolates recovered. Acquired ampC genes (blaCMY-2, blaDHA-1, blaCMY-4 and blaACC-1) were found in 19 (24.7%) of these isolates, including 14 E. coli, two K. pneumoniae and three P. mirabilis isolates. The differential trait for the presence of colonies in the inhibition halo was 100% sensitive and specific. Similar results were obtained for the cloxacillin test, except for the E. coli isolates in which specificity was 10.3%. CONCLUSION: The phenotypic trait described here can be considered useful for suspecting the presence of these enzymes. The cloxacillin test was only useful in isolates lacking a natural AmpC beta-lactamase.

Group A streptococcal infections in injection drug users in Barcelona, Spain: epidemiologic, clinical, and microbiologic analysis of 3 clusters of cases from 2000 to 2003.

An unexplained resurgence of Group A streptococci (GAS) infections has been observed since the mid-1980s in the United States and Europe, particularly among intravenous drug users (IDUs). Several risk factors have been identified. Mutations in the capsule synthesis regulator genes (csrRS) have been associated with an increase in virulence. From January 1998 to December 2003, we conducted a prospective and retrospective descriptive analysis of invasive GAS soft-tissue infections in IDUs in Barcelona, Spain. Clinical features were collected, and we conducted a surveillance study to identify risk factors associated with GAS soft-tissue infections. We analyzed chromosomal DNA by low cleavage restriction enzymes and used pulsed-field gel electrophoresis (PFGE) and variable gene sequence typing (VGST) of the emm gene to disclose the epidemiologic relationship between the strains. We analyzed the influence of clonality (M-type) and mutations in csrRS genes of these strains on clinical features. We identified 44 cases, all of which were grouped in 3 clusters: fall 2000, fall 2002, and fall 2003. Cellulitis with or without abscesses (75%) and fever (90.9%) were the most common clinical manifestations. Distant septic complications were infrequent (18.2%). Although all patients had severe infections (mainly bacteremic needle abscesses), their outcome with antibiotic therapy, usually beta-lactam, was successful in all cases. However, surgery was needed in 40.9% of patients. Through the surveillance study we found that infected patients had a higher number of drug injections per day (odds ratio [OR], 18.84; 95% confidence interval [CI], 4.83-79.4; p<0.00001), shared paraphernalia for drug use more frequently (OR, 11.11; 95% CI, 3.24-39.04; p<0.0001), were in a higher proportion both currently unemployed and homeless (OR, 4.22; 95% CI, 1.5-12.15; p<0.0001), were not in a methadone maintenance program (OR, 0.03; 95% CI, 0-0.19; p<0.00001), and more often bought drugs at a specific site (OR, 33.92; 95% CI, 7.44-174.93; p<0.00001) and from a specific dealer (OR, 72; 95% CI, 8-3090; p<0.00001), compared with patients not infected. The fall 2000 cluster was polyclonal, whereas the other 2 clusters were mainly due to the same strain of GAS (emm 25.2), and were defined as epidemic outbreaks. Clinically, the cases due to the clonal strain presented abscesses and needed surgery more frequently (p<0.001 and p=0.005, respectively). On the other hand, mutations in the csrRS genes were not associated with invasive GAS soft-tissue infection. There has been an increase in the number of cases of invasive GAS soft-tissue infections in IDUs in Barcelona, which seems to be related to drug users' habits and their socioeconomic status. Clonality (emm 25.2) but not mutations in the csrRS genes was associated with more severe GAS soft-tissue infections.

Spontaneous Listeria monocytogenes peritonitis: a population-based study of 13 cases collected in Spain.

OBJECTIVES: We aimed to assess the incidence, demographic data, clinical features, and outcome of peritoneal infections due to Listeria monocytogenes in individuals with cirrhosis. METHODS: During a 10-yr study period, 153 cases of invasive listeriosis were recorded in a prospective population-based surveillance project carried out in Barcelona, Spain. RESULTS: Thirteen cases were of spontaneous bacterial peritonitis by L. monocytogenes. Ages of the patients ranged between 29 and 85 yr. In addition to cirrhosis, underlying conditions included diabetes mellitus in four and malignancy in three. Bacteremia was present in six cases (46%). Only one patient with bacteremia developed meningitis. Analysis of the peritoneal fluid showed a mean (SD) protein content of 21.5 (9.6) g/L and leukocyte count of 7,273 (9,171) cells/ml. L. monocytogenes serotype 4b was the serogroup predominantly isolated (61%). The mortality rate was 30.7%. Eight patients received empirical antibiotic treatment with cephalosporins. CONCLUSIONS: In geographical areas with a high incidence of listeriosis, L. monocytogenes should be suspected as a causative pathogen of spontaneous bacterial peritonitis in cirrhosis. Early adjustment of antibiotic therapy is essential to reduce mortality.