Jorge Sampaio

An outbreak of Mycobacterium chelonae infection after LASIK

OBJECTIVE To describe an outbreak of mycobacterial keratitis after laser in situ keratomileusis (LASIK), including the microbiologic investigation, clinical findings, treatment response, and outcome. DESIGN Retrospective, noncomparative, interventional case series. PARTICIPANTS Patients (n = 10) who underwent LASIK surgery between August 22 and September 4, 2000, and developed mycobacterial infection. METHODS Patients were prospectively followed in relation to microbiologic investigation, clinical findings, treatment response, and outcome. MAIN OUTCOME MEASURES Most patients underwent bilateral simultaneous LASIK. Postoperative infection was signaled by the appearance of corneal infiltrates in the third postoperative week. The microbiologic workup was performed on cultures obtained either by direct scraping of the cornea or by lifting the flap. Medical therapy was instituted based on drug susceptibility testing. Surgical interventions such as corneal debridement and flap removal were performed during recurrences or when there was no satisfactory clinical response. RESULTS Cultures revealed Mycobacterium subspecies chelonae. Patients were treated with topical clarithromycin (1%), tobramycin (1.4%), and ofloxacin (0.3%). Oral clarithromycin (500 mg twice a day) was prescribed for those patients who did not respond clinically to topical treatment. Four eyes healed on this regimen. Flap removal was necessary in seven eyes. CONCLUSIONS This report highlights mycobacteria as an etiologic infectious agent after LASIK. Diagnosis can be difficult and is often delayed. The treatment mainstay is prolonged antibiotic therapy. Surgical debridement and flap removal may shorten the disease course.

Involvement of pmrAB and phoPQ in polymyxin B adaptation and inducible resistance in non-cystic fibrosis clinical isolates of Pseudomonas aeruginosa.

ABSTRACT During investigation of susceptibility testing methods for polymyxins, 24 multidrug-resistant clinical isolates of Pseudomonas aeruginosa were observed to have a distinct, reproducible phenotype in which skipped wells were observed during broth microdilution testing for polymyxin B. Possible mechanisms underlying this phenotype were investigated. The effects of various concentrations of polymyxin B on growth, the expression of resistance genes, and outer-membrane permeability were observed. Real-time PCR was performed to compare the expression, in response to selected concentrations of polymyxin B, of genes related to the PhoP-PhoQ and PmrA-PmrB two-component regulatory systems in polymyxin B-susceptible isolate PAO1, polymyxin B-resistant isolate 9BR, and two isolates (19BR and 213BR) exhibiting the skipped-well phenotype. 19BR and 213BR appeared to have similar basal levels of expression compared to that of PAO1 for phoQ, arnB, and PA4773 (from the pmrAB operon), and in contrast, 9BR had 52- and 280-fold higher expression of arnB and PA4773, respectively. The expression of arnB and PA4773 increased in response to polymyxin B in a concentration-dependent manner for 9BR but not for 19BR and 213BR. For these isolates, expression was significantly increased for arnB and PA4773, as well as phoQ, only upon exposure to 2 μg/ml polymyxin B but not at a lower concentration of 0.125 μg/ml. The sequencing of the pmrAB and phoPQ operons for all three isolates revealed a number of unique mutations compared to that for PAO1. 1-N-phenylnaphthylamine (NPN) was used to study the effect of preincubation with polymyxin B on the self-promoted uptake of polymyxin B across the outer membrane. The preincubation of cells with 2 μg/ml polymyxin B affected baseline membrane permeability in 19BR and 213BR and also resulted in a reduced rate of NPN uptake in these isolates and in PAO1 but not in 9BR. The results presented here suggest that the skipped-well isolates have the ability to adapt to specific concentrations of polymyxin B, inducing known polymyxin B resistance genes involved in generating alterations in the outer membrane.

Antibiotic resistance and trend of urinary pathogens in general outpatients from a major urban city

OBJECTIVE We assessed the antimicrobial resistance patterns of pathogens responsible for urinary tract infections (UTI) in outpatients in São Paulo, Brazil, as well as the Escherichia coli antimicrobial resistance trend. MATERIALS AND METHODS Outpatients urine cultures were collected from January 2000 to December 2003. Statistical analysis considered positive results for one bacterial species with colony count >or= 100,000 CFU/mL. Stratification was done on age group and gender. Statistical tests used included chi-square and the chi-square test for trend to evaluate differences between susceptibility rates among age groups and ordering in the E. coli resistance rates per year, respectively. RESULTS There were 37,261 positive results with Enterobacteriaceae isolated in 32,530 (87.3%) and Gram-positive cocci in 2,570 (6.9%) cultures. E. coli had the highest prevalence (71.6%). Susceptibility tests were performed in 31,716 cultures. E. coli had elevated resistance rates (> 30%) to ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. Significant differences between age groups and ordering among years were observed. CONCLUSIONS The use of trimethoprim-sulfamethoxazole is precluded in the population studied due to elevated resistance rates (> 30%) among most prevalent pathogens. Significant resistance rate differences among age groups and years were observed, particularly for fluoroquinolones. Fluoroquinolones should be used with caution. Nitrofurantoin should be used as empirical therapy for primary, non-complicated urinary tract infections.

Antimicrobial susceptibility of Gram-negative bacteria in Brazilian hospitals: the MYSTIC Program Brazil 2003

Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2003. Gram-negative bacteria (n = 1,550) causing nosocomial infections were collected at 20 Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by Etest methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). Pseudomonas aeruginosa (30.3%) was the most frequent isolate, followed by E. coli (18.6%), Klebsiella pneumoniae (16.9%), Acitenobacter baumannii (8.8%), and Enterobacter cloacae (7.1%). Pseudomonas aeruginosa (n=470) isolates presented susceptibility rates of 64% to meropenem, 63.8% to piperacillin/tazobactam, 63.4% to amikacin, 58.7% to imipenem. Acitenobacter baumannii presented susceptibility rates to meropenem of 97.1%, and 73% to tobramycin. E. coli and K. pneumoniae were highly susceptible to both carbapenems. Carbapenem resistance among the Enterobacteriaceae is still rare in the region. Acitenobacter baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since they play an important role in nosocomial infections in this environment, the use of empirical combination therapy to treat these pathogens may be justified.

Infectious post-LASIK crystalline keratopathy caused by nontuberculous mycobacteria.

Purpose. To report three cases of infectious crystalline keratopathy caused by non-tuberculous mycobacteria after LASIK surgery. Methods. Interventional case reports and literature review. Results. Infectious keratitis with clinical features of crystalline keratopathy after LASIK is described. Culture revealed Mycobacterium chelonae from the corneal scrapings of the three patients, all of whom underwent medical and surgical (debridement) treatment. Conclusions. Mycobacteria may cause infectious crystalline keratopathy after LASIK. The presence of crystalline keratopathy in patients that underwent LASIK must be considered an indicator of nontuberculous mycobacteria infection. Microbiologic work-up of a corneal specimen is required for the institution of appropriate therapy.

An Outbreak of Keratitis Caused by Mycobacterium immunogenum

ABSTRACT From 8 October to 12 November 2003, 36 patients underwent surgical correction of myopia in a São Paulo, Brazil, clinic. Five patients had clinical signs of infectious keratitis, and a Mycobacterium species with previously unreported patterns determined by PCR restriction enzyme analysis of the hsp65 gene and PCR restriction enzyme analysis of the 16S-23S rRNA internal transcribed spacer (ITS) was isolated from corneal scrapings from four of these patients. Subsequent evaluation by phenotypic tests and partial sequencing of the hsp65, sodA, rpoB, and 16S rRNA genes and the ITS supported the species identification as a variant of Mycobacterium immunogenum. The source of infection was not determined. The outbreak was caused by a single clone, as evidenced by identical pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus-PCR profiles. This is the first report of an outbreak where this species was isolated from infected tissues.

Evaluation of the in vitro activity of cefepime compared to other broad-spectrum cephalosporins against clinical isolates from eighteen Brazilian hospitals by using the Etest.

The in vitro activity of cefepime was compared to that of ceftazidime, ceftriaxone, and cefotaxime in a multicenter study involving 10 clinical microbiology laboratories and clinical isolates from 18 Brazilian hospitals from 7 cities (4 states). A total of 982 isolates consecutively collected between December 1995 and March 1996 were susceptibility tested by using Etest and following the NCCLS procedures for agar diffusion tests. The cefepime spectrum was broader than that of the other broad-spectrum cephalosporins against both Gram-negative rods and Gram-positive cocci. Cefepime was particularly more active against Enterobacter sp. (MIC90, 2 micrograms/ml), Serratia sp. (MIC90, 2 micrograms/ml) and oxacillin-susceptible Staphylococcus aureus (MIC90, 3 micrograms/ml). Against Pseudomonas aeruginosa, cefepime (MIC90, 16 micrograms/ml) was slightly more active than ceftazidime (MIC90, 32 micrograms/ml) and 8- to 16-fold more active than ceftriaxone of cefotaxime (MIC90, > 256 micrograms/ml). Our results show that nosocomial bacteria, especially Gram-negative rods, have a high rate of cephalosporin resistance in Brazil. However, part of these resistant bacteria remains susceptible to cefepime. The Etest was shown to be an excellent method for multicenter studies of the in vitro evaluation of new antimicrobial agents.

In Vitro Activity of Fluoroquinolones Against mycobacterium abscessus and mycobacterium chelonae Causing Infectious Keratitis After Lasik in Brazil

To evaluate the in vitro activity of fluoroquinolones against Mycobacterium abscessus and Mycobacterium chelonae isolated from outbreaks of infectious keratitis in Brazil. Material and Methods: Micobacterial isolates were recovered from infectious keratitis cases related outbreaks that occurred in Brazil after LASIK for myopia. Two outbreaks occurred in Rio de Janeiro in 1998 and 1999, and 3 in São Paulo between 2000 and 2003. All laboratorial analysis, including molecular identification and antibiotic susceptibility testing with determination of the minimum inhibitory concentration (MIC) levels for ciprofloxacin, ofloxacin, gatifloxacin, and moxifloxacin, were performed at Universidade Federal de São Paulo in Brazil. Results: Fifteen samples were identified as M. chelonae, and 3 were identified as M. abscessus. The outbreaks studied were designated SP-1 in 2000; SP-2 in 2000-2001; and SP-3 in 2003, R1 in 1988 and R2 in 1999. All but 1 of the M. chelonae were resistant to all fluoroquinolones with an MIC90 greater than 32 μg/mL. The only susceptible isolate had MIC levels for ciprofloxacin, ofloxacin, gatifloxacin, and moxifloxacin of 0.38 μg/mL, 0.032 μg/mL, 0.047 μg/mL, and 0.19 μg/mL, respectively. MIC levels for all 3 M. abscessus isolates tested were greater then 32 μg/mL for all fluoroquinolones tested. Conclusions: Fluoroquinolone MICs for 17 M. abscessus and M. chelonae isolates recovered from infectious keratitis cases in Brazil indicate that they are not susceptible to these drugs in vitro. Further studies to investigate the in vivo effectiveness of fluoroquinolones against mycobacteria are required because in vitro tests do not support their use in the treatment of micobacterial keratitis in this particular geographic area.

Perfil de sensibilidade a antimicrobianos de bactérias isoladas do trato respiratório baixo de pacientes com pneumonia internados em hospitais brasileiros: resultados do Programa SENTRY, 1997 e 1998

Background: Nosocomial pneumonia is the most common fatal nosocomial infection with attributable mortality rates ranging from 30 to 60% and a rapid initiation of optimal antimicrobial therapy is important to obtain treatment success. SENTRY is a comprehensive antimicrobial surveillance study involving a great number of medical centers distributed worldwide. Objective: To evaluate the antimicrobial susceptibility of bacterial isolates collected from the lower respiratory tract of inpatients with pneumonia. Material & methods: The authors report the antimicrobial susceptibility of 525 isolates collected in 11 Brazilian hospitals, as part of the SENTRY program. The isolates were tested for susceptibility by broth micro-dilution against a large number of drugs. Results: The five most frequently isolated species were (n/%): Pseudomonas aeruginosa (158/30.1%), Staphylococcus aureus (103/19.6%), Acinetobacter spp. (68/13.0%), Klebsiella spp. (50/9.5%), and Enterobacter spp. (44/8.4%). These five species represented more than 80% of all isolates. P. aeruginosa demonstrated high rates of resistance to most antimicrobial agents tested. The highest susceptibility rates were shown by piperacillin/tazobactam (71.5%) and meropenem (69.0%). Acinetobacter spp. also showed very high rates of resistance. The most active compounds against this species were imipenem and meropenem (80.9% susceptibility) followed by tetracycline (63.2% susceptibility). Cephalosporin susceptibilities among Klebsiella spp were very low and 36.0% of isolates were considered ESBL producers based on increased MICs, > 2 mg/mL) to ceftriaxone or ceftazidime or aztreonam. Ceftriaxone was active against only 56.8% of Enterobacter spp. isolates (MIC50 1 mg/mL), while cefepime was active against 88.6% of these isolates (MIC, < 0.12 mg/mL). Oxacillin-resistance was detected in 43.7% of S. aureus isolates. The most active drugs against this species were vancomycin, teicoplanin, quinupristin/dalfopristin, and linezolid. Conclusion: The results of this study demonstrated a higher prevalence of Acinetobacter spp. and higher resistance rates among Gram-negative rods when compared with results from North American and European studies.

Polymyxin B Resistance in Carbapenem-Resistant Klebsiella pneumoniae, São Paulo, Brazil.

To the Editor: Infections caused by carbapenem-resistant Enterobacteriaceae have been associated with higher death rates than infections caused by carbapenem-susceptible strains, and resistant infections are mostly treated with polymyxins (1). Several outbreaks caused by carbapenem- and polymyxin-resistant Klebsiella pneumoniae (CPRKp) have been reported, mainly from Europe, and represent an emerging threat.