Persistence of a clone of methicillin-resistant Staphylococcus aureus in a burns unit.

A total of 128 MRSA isolates from a burns unit in 1992 and 1997 was studied by resistotyping, plasmid analysis and pulsed-field gel electrophoresis (PFGE) of SmaI-digested chromosomal DNA to ascertain whether a clone of MRSA had persisted in the unit or whether different clones had been introduced at different times. All the MRSA isolates produced beta-lactamase and had high MICs to methicillin (>256 mg/L). All were resistant to tetracycline, kanamycin, cadmium acetate and mercuric chloride. Most were resistant to gentamicin, neomycin, erythromycin, chloramphenicol, trimethoprim, ciprofloxacin, propamidine isethionate and ethidium bromide, and were susceptible to minocycline, vancomycin and teicoplanin. None of the 1992 isolates was resistant to mupirocin, but 56% and 19% of the 1997 isolates expressed high- and low-level mupirocin resistance, respectively. Many of the 1997 isolates had acquired a 38-kb plasmid encoding high-level mupirocin resistance. The 1992 isolates had two main PFGE patterns; 82% of them belonged to PFGE pattern 1. The 1997 isolates had PFGE pattern 1, the same as the majority of the 1992 isolates. All MRSA isolates from both years carried the mecA gene in the same SmaI fragment. These findings demonstrated that a clone of MRSA that was prevalentin the burns unit in 1992 had persisted and became the predominant clone in 1997.

Prevalence of penicillin-resistant Streptococcus pneumoniae in Kuwait.

The worldwide incidence of penicillin-resistant Streptococcus pneumoniae has increased at an alarming rate during the past decade. However, there has been little published data about the extent of this problem in Kuwait. The present study was undertaken to ascertain the preponderance of S. pneumoniae, either resistant or intermediate-resistant to penicillin, other beta-lactams and non-beta-lactam antimicrobials in Kuwait. Two hundred and fifty fresh isolates from as many patients suffering from different clinical conditions were collected from all clinics and hospitals in Kuwait. Optochin sensitivity and bile solubility tests reconfirmed these. Susceptibility testing to penicillin, ampicillin, cefuroxime, ceftriaxone, cefotaxime, imipenem, erythromycin, chloramphenicol, ciprofloxacin and vancomycin was done using E-test strips and to oxacillin, tetracycline, trimethoprim and amoxicillin-clavulanate by disc diffusion technique. Full and intermediate resistance to penicillin was observed in 1.6% and 52.8% of the isolates respectively. Full resistance to third-generation cephalosporins ranged from 0.4% to 3.2%, however, intermediate resistance to these antibiotics varied between 18.8% and 21.2%. Ampicillin resistance was noted in 0.8%, but 40.4% of isolates were intermediately resistant. However, only 0.4% of the isolates showed either intermediate or full resistance to amoxicillin-clavulanate. Resistance to imipenem was observed in 0.4% and intermediate to 13.6% of the organisms. The rates of S. pneumoniae resistant to chloramphenicol, erythromycin, tetracycline and trimethoprim were between 8.4% and 37.6% and intermediate resistance between 1.2% and 17.6% while only 0.4% showed resistance to ciprofloxacin and none to vancomycin. Multiresistance to both beta-lactam and non-beta-lactam antibiotics was observed in 52% of the penicillin-resistant isolates.

Molecular analysis of Vibrio cholerae O1, O139, non-O1, and non-O139 strains: clonal relationships between clinical and environmental isolates.

A total of 26 strains of Vibrio cholerae, including members of the O1, O139, and non-O1, non-O139 serogroups from both clinical and environmental sources, were examined for the presence of genes encoding cholera toxin (ctxA), zonula occludens toxin (zot), accessory cholera enterotoxin (ace), hemolysin (hlyA), NAG-specific heat-stable toxin (st), toxin-coregulated pilus (tcpA), and outer membrane protein (ompU), for genomic organization, and for the presence of the regulatory protein genes tcpI and toxR in order to determine relationships between epidemic serotypes and sources of isolation. While 22 of the 26 strains were hemolytic on 5% sheep blood nutrient agar, all strains were PCR positive for hlyA, the hemolysin gene. When multiplex PCR was used, all serogroup O1 and O139 strains were positive for tcpA, ompU, and tcpI. All O1 and O139 strains except one O1 strain and one O139 strain were positive for the ctxA, zot, and ace genes. Also, O1 strain VO3 was negative for the zot gene. All of the non-O1, non-O139 strains were negative for the ctxA, zot, ace, tcpA, and tcpI genes, and all of the non-O1, non-O139 strains except strain VO26 were negative for ompU. All of the strains except non-O1, non-O139 strain VO22 were PCR positive for the gene encoding the central regulatory protein, toxR. All V. cholerae strains were negative for the NAG-specific st gene. Of the nine non-ctx-producing strains of V. cholerae, only one, non-O1, non-O139 strain VO24, caused fluid accumulation in the rabbit ileal loop assay. The other eight strains, including an O1 strain, an O139 strain, and six non-O1, non-O139 strains, regardless of the source of isolation, caused fluid accumulation after two to five serial passages through the rabbit gut. Culture filtrates of all non-cholera-toxigenic strains grown in AKI media also caused fluid accumulation, suggesting that a new toxin was produced in AKI medium by these strains. Studies of clonality performed by using enterobacterial repetitive intergenic consensus sequence PCR, Box element PCR, amplified fragment length polymorphism (AFLP), and pulsed-field gel electrophoresis (PFGE) collectively indicated that the V. cholerae O1 and O139 strains had a clonal origin, whereas the non-O1, non-O139 strains belonged to different clones. The clinical isolates closely resembled environmental isolates in their genomic patterns. Overall, there was an excellent correlation among the results of the PCR, AFLP, and PFGE analyses, and individual strains derived from clinical and environmental sources produced similar fingerprint patterns. From the results of this study, we concluded that the non-cholera-toxin-producing strains of V. cholerae, whether of clinical or environmental origin, possess the ability to produce a new secretogenic toxin that is entirely different from the toxin produced by toxigenic V. cholerae O1 and O139 strains. We also concluded that the aquatic environment is a reservoir for V. cholerae O1, O139, non-O1, and non-O139 serogroup strains.

Surgical management of echinococcosis of the heart.

A 23-year-old female with an echinococcal cyst in the atrioventricular groove of the heart is reported. The diagnosis and the location of the cyst were confirmed by echocardiography and cardiac catheter. Successful enucleating of the cyst with the aid of cardiopulmonary bypass and the length of follow-up is reported, along with a review of relevant literature.

Candidemia in pediatric surgery patients.

Candida spp. are the fourth leading cause of bloodstream infection. While the literature on neonatal candidemia is abundant, its prevalence in pediatric surgery cases is hardly mentioned. This study was carried out over a 5-year period to evaluate the prevalence of candidemia in pediatric surgery intensive care unit patients (ICU), and to examine both the neonatal and hospital risk factors for developing candidemia in comparison to control groups of patients with either no infection or with bacteremia, type and outcome of therapy. A total of 1,359 pediatric surgery patients admitted to the ICU and high dependency unit (HDU) were included in the study. Using relevant specimens from them, a microbiological survey was carried out on admission and weekly thereafter. Twenty-five patients developed candidemia during the study period. Twenty-one of them were admitted to ICU. Nine were low birth weight and immature neonates. All 25 patients had underlying disease, most involving the gastroentestinal tract and requiring surgical intervention. All patients had been given broad-spectrum beta-lactam antibiotics with or without aminoglycosides and an anti-anaerobic drug prior to candidemia. The data show that patients who were not infected had very few risk factors that could predispose to candidemia. The bacteremic group of patients had more risk factors: mainly ICU stay, prior antibiotic therapy or GI surgery. The candidemia patients outnumbered these two groups in both neonatal and hospital risk factors. Twenty-three candidemia patients had received amphotericin B and 2 had fluconazole. Seventeen of them improved and the rest expired during therapy. Fourteen of the Candida isolated were C. albicans while the rest belonged to other Candida spp. dominated by C. parapsilosis. In conclusion, candidemia was infrequent in pediatric surgery patients. ICU stay, GI surgery and prior broad-spectrum antibiotic therapy were important risk factors.

Rapid detection of methicillin resistance in staphylococci using a slide latex agglutination kit.

The slide latex agglutination test, MRSA-Screen, was compared with the mecA polymerase chain reaction (PCR) and traditional susceptibility test methods for the detection of methicillin resistance in Staphylococcus aureus and coagulase-negative staphylococci. The MRSA-Screen test detected the same number of methicillin-resistant S. aureus as the mecA PCR and the traditional susceptibility tests. It correctly identified all 21 methicillin-susceptible S. aureus as being sensitive. It also produced the same result as the mecA PCR in identifying a methicillin-resistant S. aureus among six isolates classified as borderline resistant by traditional susceptibility tests. The MRSA-Screen test and mecA PCR detected methicillin resistance in 10 and 15 of 17 methicillin-resistant coagulase-negative staphylococci, respectively. From these results, it is concluded that the MRSA-Screen is a very accurate, reliable and rapid method of detecting methicillin resistance in S. aureus and is suitable for use in clinical microbiology laboratories. Further study of its use in detecting methicillin resistance in coagulase-negative staphylococci is required.

Staphylococcal septicaemia in burns.

This study analyses staphylococcal septicaemia in a series of 1516 burn patients who were admitted to the burn unit of the Al-Babtain Centre for Burns and Plastic Surgery, Ibn Sina Hospital, Kuwait over a period of 6.5 years (1 June 1992-31 December 1998). One hundred and nine patients (7.2%) developed clinically and microbiologically proven septicaemia, of which 80 (73.4%) showed one or the other type of Staphylococcus in their blood. Fifty (62.5%) of them were males and 30 (37.5%) females, with a mean age of 26 years and the mean total body surface area of burns (TBSA) of 45% (range 1-93%). Preschool age children comprised 27.5% of the patients. Flame was the dominant (80%) cause of burn. Of the 80 patients who had 91 episodes of septicaemia, 52 (65%) had MRSA, 8 (10%) MSSA, 11 (13.8%) MRSE and 5 (6.2%) MSSE and 4 (5%) others had mixed organisms. Only the patients with MRSA had multiple episodes. Eight patients (10%) showed septicaemic episodes within only 48 h of admission; however, the majority of the patients (77.5%) had a septicaemic attack within 2 weeks postburn. Of the 52 MRSA septicaemic cases, 39 (75%) survived and 13 (25%) died. Four patients with septicaemia due to mixed infections died. A total of 19 patients were intubated, 14 due to inhalation injury and 5 because of septicaemia; all in the former group died. Glycopeptide therapy (vancomycin/teicoplanin) was instituted immediately following the detection of staphylococci in the blood. No significant difference was noted in relation to mortality amongst the septicaemic patients, whether or not on prophylactic antibiotic. Fifty-six (70%) of the 80 patients had 139 sessions of skin grafting and survived. Of the 52 MRSA patients, 40 had 101 sessions of skin grafting and 33 of them survived. The apparent low mortality was probably due to early detection of the organism, appropriate antibiotic therapy, care for nutrition and early wound cover. This study indicates a high incidence of staphylococcal septicaemia (especially due to MRSA) in the burn unit. A surface wound is the likely source of entry to the blood stream in these immunocompromised patients. The organism could be detected in blood as early as 48 h postburn and in as little TBSA burn as 1% in this MRSA endemic unit. Inhalation injury with major burns and added staphylococcal septicaemia invariably proved to be fatal.

Cholera in its present day scenario.

Cholera existed in many parts of the world since olden days. Gangetic delta is considered as the home of the disease. Since 1970 there has been a significant development of the disease with its ecologic and epidemiologic aspects. Vibrio cholerae non-01 strain in taxonomically separated from V cholerae 01 strain. Though 01 strain causes epidemic outbreaks, still non-01 has been implicated to cause cholera like illness. While humans are long considered to be the only reservoir of V cholerae 01 strain, but the organism appears to have a free-living cycle in the natural environment. The organism survives more rapidly in the brackish water than fresh water. It has been demonstrated that V cholerae undergoes conversion to a viable but non-culturable state, whereby the cells are reduced in size, become ovoid, but in contrast to starved cells, do not grow at all on standard laboratory media. Seasonality coupled with starvation response and dormancy phenomenon, reflects the origin of V cholerae as an autochthonous estuary dweller. All biotypes of this organism can grow on media containing chitin as the sole carbon source. Outbreaks of the disease are related to plankton blooms associated with warmer sea-surface temperature. In 1997 V cholerae 01 biotype El tor continued to occur in all regions of the world. In 1982 a new classical variant initially displaced entrenched El tor in Bangladesh and coexisted with it for almost a decade. V cholerae 0139 Bangal has arisen along the Bay of Bengal and has spread in Asia.

Pseudomonas aeruginosa septicaemia in burns.

Out of 1415 patients treated as inpatients at Al-Babtain Center for Burns and Plastic Surgery, Ibn Sina Hospital, Kuwait spanning over a period of 6 years from June 1992 to June 1998, 102 developed clinically and microbiologically proven septicaemia. Only 15 out of them had either single or multiple episodes of septicaemia due to Pseudomonas aeruginosa and were studied during their stay in the hospital. Five of them were males and 10 females, with a mean age of 26 years (range 3-51 years) and mean total body surface area of burns (TBSA) of 66% (range 25-90%). All of them had flame burns and resuscitation was found to be difficult in eight patients either due to delayed hospitalization or accompanied inhalation injury. Seven patients were intubated, four due to inhalation injury and three for septicaemic complications. Among the 15 patients under study, a total of 36 septicaemic episodes were detected of which 21 were due to P. aeruginosa. This organism was found in the first episodes in nine patients, in second episodes in six, in third episodes in three and fourth, fifth and sixth episodes in one patient, each at a variable postburn day. Ten patients had 38 sessions of excision and skin grafting, six of them survived. Nine of the 15 patients under study died due to septicaemia, but only six of them had P. aeruginosa as the last isolate. Except for one, all patients had > 40% TBSA burn, two had difficult resuscitation and four were intubated. The day of death varied between 3 to 52 days postburn (mean 19 days). This study showed that females with flame burns are susceptible to P. aeruginosa septicaemia. Difficult resuscitation and intubation also proved to be important risk factors. Septicaemia could occur quite early in the postburn days and the mortality due to this organism was quite high. Early excision and grafting with other effective management may result in a better outcome.

Rifampicin as an adjunct to vancomycin therapy in MRSA septicaemia in burns.

Rifampicin has been successfully used as an adjunct to vancomycin therapy in several clinical conditions of MRSA infections such as endocarditis, ventriculoperitoneal shunts and septicaemia. However, very little information is available in the literature regarding its use in MRSA septicaemia in burns. The present prospective study was conducted to evaluate the efficacy of rifampicin as an adjunct therapy in burn cases with MRSA septicaemia not responding well to vancomycin. Fourteen out of 36 MRSA septicaemia patients with burns who either did not or only partially responded to therapeutic doses of vancomycin within 5-6 days were treated with rifampicin as an adjunct therapy (600 mg, i.v., o.d) for 5 days during the study period between January 1995 to December 1998. All the patients had burns due to flame and the TBSA varied between 20-90% with a mean of 64%. Eleven patients had deep and three had mixed burns. MRSA septicaemic episodes usually followed 2 3 days of detection of the organism in burn wounds. All the isolates were sensitive to vancomycin with an MIC of < or = 1.0 mg/L and were treated with vancomycin, (500 mg, i.v., 6 hourly). The serum vancomycin levels in all the patients were within the therapeutic range. However, blood cultures still remained positive even after 5-6 days of therapy. Institution of rifampicin, as an adjunct to vancomycin therapy to which the MRSA isolates were susceptible, showed a dramatic clinical response and survival of grafts. Thirteen patients survived and one died who had 70% deep burns and blood cultures revealed a multiresistant Acinetobacter in addition to MRSA. The present study thus confirms the efficacy of clinical use of rifampicin as an adjunct in vancomycin nonresponding cases of MRSA septicaemia in burns.

Resistance patterns of Pseudomonas aeruginosa to carbapenems and piperacillin/tazobactam.

Pseudomonas aeruginosa is a major problem as a multiresistant nosocomial pathogen, especially in burns and other immunocompromised patients in our hospital. The present prospective study, conducted between June 1996 and December 1997, was aimed at determining the extent of its resistance against highly active antipseudomonal drugs, such as carbapenems (imipenem and meropenem) and ureidopenicillin with beta-lactamase inhibitor (piperacillin/tazobactam); existence of any cross resistance or difference in susceptibility between imipenem and meropenem; and to compare the activity of piperacillin/tazobactam with the two carbapenems against P. aeruginosa. Of the 357 P. aeruginosa isolates tested from 188 patients 37 (10.4%) were resistant to imipenem, 21 (5.9%) to meropenem and 50 (14%) to piperacillin/tazobactam. Cross resistance between the two carbapenems was observed in 5.9% of the isolates. Sixteen (43%) of the imipenem-resistant isolates were susceptible to meropenem but the reverse was observed in none. Amongst the 50 piperacillin/tazobactam-resistant isolates cross resistance with the two carbapenems was observed in 18 (36%) and in 9 (18%) only with imipenem; 23 (46%) were susceptible to both. Our results indicate that P. aeruginosa is least resistant to meropenem followed by imipenem and piperacillin/tazobactam. Cross resistance between the carbapenems and between carbapenems and piperacillin/tazobactam was found. The study further suggests that burns, cardiac-neuro-pediatric surgical, cancer and transplant patients are more susceptible to acquiring infection due to multiresistant P. aeruginosa than other types of patients and common infection sites were wounds, respiratory tract, urine, blood and intravascular lines.

Beta-haemolytic Streptococcus infection in burns.

Group A beta haemolytic Streptococcus has been one of the most serious infections in the burn patients resulting in severe cellulitis and sepsis. Penicillin has been used ever since its introduction as prophylaxis against these conditions. Penicillin prophylaxis was used in our burn unit as well without any serious evaluation until December 1992. This prospective study was therefore, undertaken to evaluate the incidence of beta haemolytic Streptococcus infection in burn patients, and its clinical outcome over a period of 5 years in the absence of prophylaxis with penicillin. 14 of the 1213 burn patients admitted to the Al-Babtain Centre for Plastic Surgery and Burns from January 1993 to December 1997 had either colonization or infection with Streptococcus spp. Their mean age was 15 years (range 1 month to 52 years) and the mean burn surface area was 20% (range 5 to 90%). Streptococci were isolated from burn wounds in 10 patients, throat in 3 and blood culture in 1. Group A Streptococcus was found in 5, group C in 3 and group D in 6 patients. In all patients except one the organisms were isolated > or =72 h post burn. The infections were successfully controlled by antibiotic and no detrimental effect was observed either on wound healing or skin graft take. There was no mortality amongst these 14 patients. The study showed that only 1.1% of the burn patients in our unit acquired Streptococcus of which only one third comprised of group A. This study thus demonstrates that the practice of penicillin prophylaxis during the first five post burn days may not be of any value and therefore, deserves discontinuation in units where the incidence of this organism is minuscule.

The increase in carbapenem use and emergence of Stenotrophomonas maltophilia as an important nosocomial pathogen.

Carbapenems, being the broadest spectrum antibiotics, may allow those organisms intrinsically resistant to these drugs to be involved more frequently in nosocomial infections. Imipenem was introduced to the specialized hospital units in Kuwait in October, 1992 and meropenem in late 1996. The main objective of this study was to observe prospectively whether, under similar laboratory conditions for microbial isolation/identification while these drugs are in use in the hospital, there is any proportional increase over time in the recovery of Stenotrophomonas maltophilia in relation to the number of yearly admissions and drug use. In addition, we also looked for categories of patients infected by S. maltophilia, type of infection and antibiotic susceptibility. There was an increase in the number of S. maltophilia isolates from 1993 to 1997 significantly correlated with the increase in year-wise consumption of carbapenems (p<0.004). No correlation was observed between yearly number of admissions and both the consumption of carbapenems (p>0.51) and isolation of the organism (p>0.59). Most isolates were from cancer, burns and cardiac patients. The commonest types of infection were wound and septicemia. The organisms were susceptible mostly to ciprofloxacin and co-trimoxazole. The study thus indicates that carbapenem use in a hospital environment may result in emergence of nosocomial infections due to multiresistant S. maltophilia in high risk patients with very limited choice of antibiotics for therapy.

Virulence patterns of Aeromonas eucrenophila isolated from water and infected fish.

Six isolates of Aeromonas eucrenophila--2 from water and 4 from superficial skin ulcer of cat fish--were examined for haemagglutination, serum sensitivity, chitinase production and enterotoxicity, and correlation, if any, between them; only one strain showed haemagglutination and was inhibited by both D-mannose and L-fucose. All the strains showed resistance to normal human serum, but produced chitinase; one of them elaborated inducible chitinase. All these strains caused fluid accumulation only after 1-4 serial passages through rabbit ileal loops, of which one strain that elaborated inducible chitinase caused significantly more (p < 0.005) fluid accumulation. These observations indicate that there is no correlation between enterotoxicity and haemagglutination and/or serum resistance, and these properties did not change after animal passage. However, a correlation could be observed between elaboration of inducible chitinase and enterotoxin production.

Enteropathogenicity and antimicrobial susceptibility of new Escherichia spp.

To determine the mechanism of enteropathogenicity of the newly described Escherichia species, a total of 50 clinical isolates of Escherichia spp. from diarrhoeal stools were studied. Twelve isolates (24%) were found to be E. vulneris, 6 (12%) E. fergusonii, 2 (4%) E. hermannii, and the rest 30 (60%) were E. coli. Most isolates of the new species were resistant to ampicillin, tetracycline, and co-trimoxazole, but were susceptible to cephalosporins and aminoglycosides. The representative strains of all the new species produced significant fluid accumulation in the rat ileal loops both by live cells and their culture filtrates. E. vulneris, isolated from stools, showed maximum fluid accumulation. Thus, it can be inferred that these species are diarrhoeagenic, but their roles on extra-intestinal infections remain to be determined.

Susceptibility of 497 clinical isolates of gram-negative anaerobes to trovafloxacin and eight other antibiotics.

Trovafloxacin is a novel investigational trifluoronaphthyridone antibiotic with broad-spectrum activity against Gram-positive and Gram-negative organisms. Its in-vitro activity and those of eight other antimicrobial agents were evaluated against 497 clinical isolates of Gram-negative anaerobic bacteria by the agar dilution method. Trovafloxacin had excellent activity, with a minimum inhibitory concentration (MIC) range of <0.03-4 microg/ml, against all species. Out of the 497 isolates tested, 496 (99.5%) were inhibited by a concentration of < or = 2.0 microg/ml of trovafloxacin; the remaining two strains were inhibited by a concentration of 4.0 microg/ml. The MIC50s and MIC90s were 0.12 microg/ml and 1.0 microg/ml, respectively. Meropenem, imipenem and piperacillin/tazobactam were also very active. Overall, at the MIC90s, trovafloxacin was as active as meropenem, slightly more active than metronidazole and imipenem, twice as active as amoxicillin-clavulanic acid, five times more active than piperacillintazobactam and 68 times more active than clindamycin. About 21% of the isolates were resistant to cefoxitin, 30% to clindamycin and 40% to piperacillin. Five species in the Bacteroides fragilis group of isolates were highly resistant to metronidazole (MIC >128 microg/ml). In general, the relatively more resistant species were the B. vulgatus, B. ovatus, B. thetaiotaomicron, and B. fragilis sensu stricto, in that order. All the isolates of the B. fragilis group and about 50% of the Prevotella spp. were beta-lactamase positive. Trovafloxacin certainly holds promise as an alternative drug for therapy of anaerobic infections.

The role of aggressive medical therapy along with early surgical intervention in the cure of Brucella endocarditis.

Timing of surgical intervention in Brucella endocarditis remains controversial. In this report, we review our experience in an attempt to collect some information on the best approach for this entity. From June 1992 to December 1996, 5 male patients between the ages of 20 and 35 years with Brucella endocarditis were operated on in our centre. Three of them had native valve endocarditis (NVE) and 2 with prosthetic valve endocarditis (PVE). All patients belonged to New York Heart Association (NYHA) class III-IV. All had developed anti Brucella antibodies with serum agglutination titres of > 320 and the sera tested from 3 patients were Enzyme Linked Immunosorbent Assay (ELISA) positive for anti-Brucella IgM and/or IgG antibodies. In 3 cases 2D-echocardiography showed large vegetation on the affected valve. Blood cultures were positive in 4 patients, 2 of them (one each of NVE and PVE) had the valve material culture positive for Brucella. All cases were treated with a combination of doxycycline, refampicine and gentamicin before surgery. Major indication for surgical intervention was severe haemodynamic instability which developed during the course of antibiotic therapy either early (3 cases) or late (2 cases). All patients became asymptomatic at the end of 7 days postoperatively. On the follow-up for a period of 8-51 months, all patients were in NYHA class I-II without evidence of recurrence of infection. These data suggest that in either NVE or PVE Brucella, medical therapy alone may not be sufficient due to the eventual haemodynamic deterioration secondary to valve tissue destruction or dysfunction of the prosthetic valve caused by the infective process. Therefore, a combination of aggressive medical therapy with multiple bactericidal antibiotics and early surgical intervention may result in a successful outcome, but further studies are needed to reach a reliable conclusion.

Burn septicaemia: an analysis of 79 patients.

Out of 943 patients treated from June 92 to May 96 at the burns unit of the Al-Babtain Centre for Plastic Surgery and Burns, Kuwait, 280 (30%) required admission to the burns intensive care unit (ICBU) and were studied retrospectively. Seventy-nine (28.2%) developed clinically and microbiologically proven septicaemia. Forty-four (56%) were males, 35 (44%) females with a mean age of 26 years (range 45 days to 75 years) and mean total body surface area burn (TBSA) of 46% (range 10-90%). Sixty-two had flame burns, 16 a scald and one had an electric burn. These 79 patients had a total of 118 septicaemic episodes. Sixty (76%) had only one and 19 (24%) had multiple episodes of septicaemia. Fifty-four (68%) had their first episode within 2weeks, though the maximum number of episodes was between 6 and 10 days postburn. Septicaemia was also observed in 13% of patients within 3 days postburn. Out of the 118 episodes, 48 were due to methicillin resistant Staphylococcus aureus (MRSA), 17 due to methicillin resistant Staphylococcus epidemidis (MRSE), 15 to Pseudomonas, 12 to Acinetobacter, four to Streptococcus, another four to Enterococci, two to Klebsiella, one due to Serratia and 15 to more than one organism. Once the septicaemia was diagnosed appropriate therapy was instituted. Fifty-six (71%) patients had 143 sessions of skin grafting and the mortality was low in operated patients. Twenty-three (29.1%) patients died. The low mortality rate was probably due to factors such as continuous clinical and microbiological surveillance leading to quick detection of aetiology, appropriate antibiotic therapy, care for nutrition and early wound cover. This study suggests that flame burn patients are more vulnerable to sepsis. Onset of septicaemia may be as early as 3 days and commonly within 2 weeks. A surface wound is the likely source of entry to the blood stream. Gram positive organisms are dominant in the aetiology. Early detection and appropriate treatment including wound coverage result in a better outcome.

In vitro activity of piperacillin/tazobactam versus other broad-spectrum antibiotics against nosocomial gram-negative pathogens isolated from burn patients.

Burn patients are at high risk for nosocomial infections due to multiresistant bacteria, a large proportion of which are gram-negative. Tazobactam, a potent inhibitor of beta-lactamases, extends the spectrum of piperacillin to include many beta-lactamase producing bacteria. Consequently, it was decided to evaluate the activity of piperacillin/tazobactam in comparison with that of eight other antibiotics that are usually used for therapy against gram-negative bacterial infections in our burn unit. All consecutive gram-negative isolates from wounds, blood, respiratory tract, urine etc. from burn patients considered to be clinically significant were tested for their susceptibility to piperacillin/tazobactam, piperacillin, ceftazidime, cefotaxime, ceftriaxone, ciprofloxacin, gentamicin, amikacin and imipenem, determined by disk diffusion test. The zone inhibition was interpreted according to NCCLS recommendations. A total of 948 strains, isolated during the period of July, 1994 to September, 1995, made up of Pseudomonas spp (326), Acinetobacter spp (268) and Enterobacteriaceae (354), were tested. Overall piperacillin/tazobactam showed superior activity over the other antibiotics except for imipenem. Of the 948 isolates, 87% were susceptible to the combination, 56% to the three third generation cephalosporins, 69% to ciprofloxacin, 59% to the aminoglycosides and 97% to imipenem. Piperacillin/tazobactam showed strikingly superior activity over piperacillin alone against Acinetobacter spp followed by Enterobacteriaceae and the least against Pseudomonas. The emergence of Acinetobacter spp as a dominant gram-negative pathogen in burn patients and its high level of resistance against most of the antibiotics tested except piperacillin/tazobactam (87%) and imipenem (100%) were significant in light of the epidemiology of burn infections and treatment. This study suggests that piperacillin/tazobactam holds good promise against gram-negative infections in burn patients.

Imipenem resistance in aerobic gram-negative bacteria.

A prospective study was undertaken to observe the emergence of resistance to imipenem, if any, among aerobic gram-negative bacteria. A total of 736 isolates were tested during 1994-95 and less than 1% of them were resistant to imipenem, whereas the next year ('95-'96) the rate increased to 11 of the 903 isolates tested. The resistant isolates during '94-'95 were all Stenotrophomonas maltophilia whereas the spectrum of resistant bacterial species increased in '95-'96 to include Pseudomonas aeruginosa, Burkholderia cepacia, Acinetobacter calcoaceticus, Enterobacter cloacae, Proteus mirabilis and Morganella morganii with a tendency to an increase in the minimum inhibitory concentration (MIC) in the later part of the year. A majority (72%) of the resistant isolates were from patients with burns, and burn wounds were most frequently infected with such organisms. These data suggest that over a period of time aerobic gram-negative bacteria may develop resistance to imipenem and the pool of such bacteria increases with extensive use of the drug. Non-fermentative aerobic bacteria tend to develop resistance faster with widespread dissemination than Enterobacteriaceae. Hospital Burn Units are a potential source of development of such resistance.