New approaches to reduce Staphylococcus aureus nosocomial infection rates: treating S. aureus nasal carriage

BACKGROUND: Nosocomial infections cause significant patient morbidity and mortality. The 2.5 million nosocomial infections that occur each year cost the US healthcare system $5 million to $10 million. Staphylococcus aureus has long been recognized as an important pathogen in human disease and is the most common cause of nosocomial infections. OBJECTIVE: To describe the epidemiology of S. aureus nosocomial infections that are attributable to patients' endogenous colonization. DATA SOURCES: Review of the English-language literature and a MEDLINE search (as of September 1997). DATA SYNTHESIS: The ecologic niche of S. aureus is the anterior nares. The prevalence of S. aureus nasal carriage is approximately 20-25%, but varies among different populations, and is influenced by age, underlying illness, race, certain behaviors, and the environment in which the person lives or works. The link between S. aureus nasal carriage and development of subsequent S. aureus infections has been established in patients on hemodialysis, on continuous ambulatory peritoneal dialysis, and those undergoing surgery. S. aureus nasal carriers have a two-to tenfold increased risk of developing S. aureus surgical site or intravenous catheter infections. Thirty percent of 100% of S. aureus infections are due to endogenous flora and infecting strains were genetically identical to nasal strains. Three treatment strategies may eliminate nasal carriage: locally applied antibiotics or disinfectants, systemic antibiotics, and bacterial interference. Among these strategies, locally applied or systemic antibiotics are most commonly used. Nasal ointments or sprays and oral antibiotics have variable efficacy and their use frequently results in antimicrobial resistance among S. aureus strains. Of the commonly used agents, mupirocin (pseudomonic acid) ointment has been shown to be 97% effective in reducing S. aureus nasal carriage. However, resistance occurs when the ointment has been applied for a prolonged period over large surface areas. CONCLUSIONS: Given the importance of S. aureus nosocomial infections and the increased risk of S. aureus nasal carriage in patients with nosocomial infections, investigators need to study cost-effective strategies to prevent certain types of nosocomial infections or nosocomial infections that occur in specific settings. One potential strategy is to decrease S. aureus nasal carriage among certain patient populations.     

Dialysis catheter-related septicaemia--focus on Staphylococcus aureus septicaemia

BACKGROUND: Dialysis catheters are a common cause of nosocomial septicaemia in haemodialysis units usually due to staphylococci, of which Staphylococcus aureus is the most pathogenic. In this study, the epidemiology and pathogenesis of dialysis catheter-related infections were studied, and methods to identify patients with these infections were evaluated. METHODS: A one-year prospective study of 67 catheters in 43 haemodialysis patients was performed. Details about patients and catheters were obtained successively during the catheter period, and biochemical parameters expected to be related to infection were measured. After catheter insertion, all patients were screened for nasal carriage of S. aureus, and a culture was taken from the skin overlying the catheter insertion site. Once a week, cultures were taken from the insertion site and from the hub, and aerobic and anaerobic blood cultures were drawn from the catheter. If clinical signs of septicaemia occurred, peripheral blood cultures were also performed, when it was possible. RESULTS: The incidence of septicaemia was 49% (21/43) in patients, and 56% of all cases were caused by S. aureus. The mortality was 14% (3/21) and the incidence of severe secondary complications to septicaemia was 24% (5/31). In all, 80% of all severe complications and 75% of all deaths from septicaemia were due to S. aureus. With respect to S. aureus septicaemia, the predictive values of positive (P) and negative (N) S. aureus cultures were as follows: nasal culture, P=36% (10/28), N=90% (35/39); culture from the insertion site, P=72% (13/18), N=98% (48/49); and culture from the hub, P=75% (3/4), N=83% (52/63). The risk ratio for S. aureus septicaemia was 26.2 (6.1-113), P=0.0001, according to the presence of S. aureus at the insertion site, and 3.3 (0.74-15.1), P=0.12 according to nasal carriage of S. aureus. The frequency of S. aureus phage-type Group 2 (43%) was much higher than the general frequency of this phage-type in Denmark, which is about 23%. Catheter blood cultures were positive although there were no clinical signs of septicaemia in 34% (23/67) of all catheter periods--84% of these were due to coagulase-negative staphylococci. CONCLUSIONS: Dialysis catheter-related S. aureus septicaemia was highly unlikely if the patient had not been carrying S. aureus in the nose or at the insertion site during the time the catheter was in place. The best predictor of dialysis catheter-related S. aureus septicaemia was a positive S. aureus culture from the insertion site. Positive catheter blood cultures unrelated to any clinical signs of septicaemia occurred in one-third of all catheter periods, and 84% of these were due to coagulase-negative staphylococci.     

Time-frequency analysis of heart murmurs. Part II: Optimisation of time-frequency representations and performance evaluation

OBJECTIVE: We hypothesized that carriage of Staphylococcus aureus among continuous ambulatory peritoneal dialysis (CAPD) patients was influenced by their spouses. Furthermore, this carrier status was compared to previous Staph. aureus peritonitis episodes in order to identify the influence of Staph. aureus carriage on peritonitis rate. DESIGN: A combined prospective surveillance study (Staph. aureus carriage) and retrospective chart review (Staph. aureus peritonitis). SETTING: A single peritoneal dialysis unit in a county hospital. PATIENTS AND METHODS: Cultures from patients (n = 32) and spouses (n = 16) were obtained twice, with a 1-month interval, from the anterior nares, the umbilical, and one groin area. All positive cultures were phage typed. Retrospective chart review of all episodes of Staph. aureus peritonitis among the patients was carried out. RESULTS: Twelve of 32 patients (37.5%) and 5 of 16 spouses (31%) evaluated were carriers. Half of the spouses of patients who were Staph. aureus carriers, were also carriers, as opposed to 20% of spouses of noncarrier patients (p = 0.30). Patients and spouses always shared the same phage type. Among patients, Staph. aureus was found in the nose only (n = 9), in all three regions (n = 2), and extranasally only (n = 1). If only one nasal culture was used to establish carriage, the sensitivity and negative predictive value would be 92% and 95%, respectively. A trend toward a higher incidence (p = 0.062) of Staph. aureus peritonitis was found among carriers (patients), 0.37 versus 0.28 peritonitis episode/dialysis-year. CONCLUSIONS: Only one positive nasal culture was necessary when carriage of Staph. aureus was to be established. Staph. aureus carriage was found more often in patients who had previously suffered from Staph. aureus peritonitis. The phage types isolated remained fairly constant, and the patients and spouses often had the same carrier state and shared the same phage types, although transmission does not always take place.     

Use of subepithelial connective tissue grafts in combined periodontal prosthetic procedures

INTRODUCTION: Occasional superinfection or co-infection with Staphylococcus aureus led us to search for S. aureus carriage prospectively in patients with non-necrotizing bacterial dermophypodermitis, in particular erysipelas. PATIENTS AND METHODS: This prospective study included immunocompetent patients with bacterial dermophypodermitis without signs of toxicity or local manifestations suggesting necrotizing fasciitis. Bacteriology tests included: 1) direct immunofluorescence for streptococcus (groups A, C, G) on skin biopsies taken on day 0, 2) samples from the nasal orifices, the intergluteal fold, and potential skin portals for bacteriology culture, and 3) assay of antistreptolysine O and antistreptodornase B on day 0 and 15. RESULTS: The study group included 42 patients (23 females, 19 males, mean age 64 +/- 3.5 yr). In 39 cases (93%) bacterial dermohypodermitis was located on the lower limb with a potential skin portal in 36 cases (86%). Sample culture, direct immunofluorescence or serology findings demonstrated presence of streptococci in 33 cases (79%). Nasal, intergluteal or potential portal were identified in 19 patients (45%) including 16 with demonstrated presence of streptococci. The rate of cure after oral pristinamycin did not vary significantly between carriers (79%) an non-carriers (91%) of Staphylococcus aureus. Drainage of a localized abscess was successful in 5 of 6 patients after initial failure of antibiotic treatment; 4 of them were carriers of S. aureus. CONCLUSION: This prospective study demonstrated that cutaneous-mucosal carriage of Staphylococcus aureus is frequent in patients with non-necrotizing dermohypodermitis. This carriage is not a factor of over-morbidity as shown in this group of infections largely dominated by erysipelas.     

Oxacillin- and quinolone-resistant Staphylococcus aureus in Sao Paulo, Brazil: a multicenter molecular epidemiology study

OBJECTIVE: To investigate the possibility of interhospital spread of multiresistant Staphylococcus aureus in Sao Paulo, Brazil. DESIGN: We evaluated 13 nosocomial S aureus strains selected because of resistance to oxacillin and ciprofloxacin. SETTING: The strains were collected between March 1991 and September 1991 from four different hospitals in Sao Paulo. Two were teaching hospitals, and two were private hospitals. PATIENTS: Each strain was isolated from a different patient. All patients were hospitalized when the strains were isolated. INTERVENTIONS: The strains were typed by restriction endonuclease analyses of plasmid DNA (REAP) using EcoRI, HindIII, RsaI, and AluI and by extended antibiogram profile (34 drugs). RESULTS: All strains had identical plasmid and antibiogram profile. They demonstrated the same plasmid pattern as previously described in one of the hospitals studied. CONCLUSIONS: Our results suggest the dissemination of a unique oxacillin- and quinolone-resistant strain of S aureus in several hospitals of Sao Paulo, Brazil.     

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

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

A molecular epidemiologic study of methicillin-resistant Staphylococcus aureus infection in patients undergoing middle ear surgery

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections after middle ear surgery has recently increased at our hospital. Most of these infections were thought to be hospital-acquired when medical personnel in contact with an MRSA-infected patient may have inadvertently transmitted the pathogen to other patients. To prevent further transmission it is essential that such sources of MRSA infection and transmission routes be selected out and eradicated. Therefore, it is necessary to determine whether the strains of MRSA isolated from infected patients are identical to those obtained from medical personnel in order to prove a reciprocal transmission of organisms between medical personnel and patients. Surveillance bacterial cultures from the anterior nares and hands of medical personnel working in the Department of Otolaryngology, Korea University Guro Hospital, were performed at two different time points: 6 December 1994 and 17 June 1996. Ribotyping with Southern blot technique was used to compare 12 MRSA strains from medical carriers with 60 strains identified from the otorrhea of MRSA-infected patients undergoing middle ear surgery. As results, six different MRSA strains were identified (types I, II, III, IV, V and VI) from ribotyping with EcoR1. One distinct subtype, type I strain, was the most frequently identified strain in both medical carriers and patients. Results also showed that 6 MRSA isolates from 10 medical carriers and 20 from 30 patients contained type I ribotype at first culture. Two medical carriers' isolates and 13 isolates from 30 patients shared the same type I strain at the second surveillance culture. In all, 41 out of 72 MRSA strains (56.9%) shared an identical ribotype pattern. Postoperative MRSA infection rates after treatment of medical carriers and the application of rigorous preventive procedures decreased from 11.9 to 5.7% after first culture and 9.0 to 7.7% following second cultures. These findings confirm that MRSA transmission can occur between medical personnel and patients and that effective preventive measures can reduce the postoperative infection rate.     

A contingency-based approach for assessing policies on aging

The analysis of genomic DNA fragment patterns has revealed as a powerful tool for strain discrimination in Staphylococcus aureus; for use as an epidemiological marker, stability during the course of an outbreak is an essential prerequisite. Genomic DNA fragment patterns (SmaI restriction, pulsed-field electrophoresis) of four different epidemic MRSA strains were compared along with intra- and interhospital and country-wide spread over more than 12 months in Germany. Strain I was isolated from infections in 8 hospitals. In one hospital a subclone arised which differed from the original strain by 4 fragments. Strain II was spread among 4 hospitals, isolates from three of these hospitals exhibited a variability of one to three fragments in the 150-200 kb range. Two hospitals in the Hannover-area were affected by strain III; in 17 isolates of this strain a variability up to three fragments was found in the 170-200 kb range. Strain IV was isolated from 19 cases of infections in 3 hospitals in Berlin. The fragment patterns were completely stable. When S. aureus strains are typed by genomic DNA fragment patterns, a variability in a definite range of molecular masses during the course of an epidemic should be taken into consideration.     

Prophylactic mupirocin could reduce orthopedic wound infections. 1,044 patients treated with mupirocin compared with 1,260 historical controls

We analyzed the effect of perioperative elimination of nasal carriage of Staphylococcus aureus using mupirocin nasal ointment on the reduction of the postoperative wound infection rate in orthopedics. In an unblinded intervention trial, we compared 1,044 patients treated with mupirocin (intervention group) with 1,260 historical controls (control group). From each group a random sample of 50 patients was taken. Risk factors were analyzed in these random samples and we found it unlikely that different distributions of risk factors might have influenced the results. The wound infection rates were 14/1,044 in the intervention group and 34/1,260 in the control group (p = 0.02). The rates of wound infections caused by S. aureus were subsequently 7/1,044 and 14/1,260 (p = 0.3). On checking the data we found that prophylaxis had unintentionally not been given to 172 patients in the intervention group. Correction of the data gave a comparable total infection rate, but a further reduced infection rate by S. aureus. Our findings suggest that prophylactic treatment with mupirocin in orthopedic surgery can reduce the infection rate.     

Adherence of Staphylococcus aureus isolated in peritoneal dialysis-related exit-site infections to HEp-2 cells and silicone peritoneal catheter materials

BACKGROUND: Peritoneal catheter exit-site infections cause a relevant morbidity in peritoneal dialysis patients and are frequently caused by Staphylococcus aureus. We tested the hypothesis that adherence of exit-site-derived S. aureus to epithelial cells and peritoneal catheter silicone tubes discriminates virulent and less virulent strains. METHODS: The binding of isolated S. aureus to an epithelial cell line (HEp-2) and to silicone tubes was analyzed using light-microscopy or radioactive labeling of bacteria. RESULTS: Of 378 exit-site swabs, 99 (26%) were positive for microbial growth. S. aureus was cultured in 25 of 99 positive swabs; three of 13 swabs taken in exit-site infections grade 3 and 4 that had tested positive for S. aureus. Adherence of S. aureus from exit-site infections grade 2, 3 and 4 to Hep-2 cells did not differ from adherence of bacteria isolated from asymptomatic or moderately inflamed catheter exit sites (grade 0-2). However, binding of S. aureus to silicone tubes was enhanced in grade 0/1 compared with grade 2-4 exit-site isolates. CONCLUSIONS: Staphylococcus aureus is an important pathogen in CAPD-related exit-site infection being isolated in about 6.6% of all exit-site swabs (and in 25% of all positive swabs). Silicone-adhesive strains may be of more clinical significance in peritoneal dialysis patients since adhesion to silicone was increased in S. aureus strains isolated in more severe exit-site infections.     

Pathologic scotopization: a shortened Nagel-II anomaloscopic micro-screw method

In order to study the possible clonal relation of Staphyloccocus (S.) intermedius from canine superficial pyoderma and from healthy carriers, isolates from pustular swabs and from vaginal, nasal and normal skin sabs were typed using macrorestriction analysis with Sma I and pulsed-field gel electrophoresis. From the size of the resulting fragments the size of the chromosome of S. intermedius could be determined to be roughly 1500 +/- 200 kb on the average. The fingerprints were very heterogeneous though characteristically distinct from patterns of (human) S. aureus as published by others. Strains from superficial pyoderma were not found to be more similar to each other than strains from healthy carriers. Therefore it was concluded that strains from this type of skin infection probably did not belong to a certain subpopulation of S. intermedius, which might have indicated a higher virulence of these strains.     

Molecular organization of the alcohol dehydrogenase loci of Drosophila grimshawi and Drosophila hawaiiensis

A total of 71 Staphylococcus aureus strains isolated from bovine mammary glands were identified and subtyped. The methods used to differentiate between the S. aureus isolates were the DNA polymorphism pattern after amplification with a Polymerase Chain Reaction using several primer combinations and phage typing. The DNA fingerprinting technique using RAPD, ERIC1R and ERIC primers proved to be useful in differentiating isolates of S. aureus. Differentiation of isolates using phage typing gave no additional information compared to the DNA technique. The outbreak of S. aureus in the herd studied was mainly caused by one S. aureus strain. Other strains were only found on three occasions, twice in subclinical infections and once from a case of clinical mastitis. In the latter case the dominant strain was isolated from a different quarter of the same cow. Four of the ten cows studied suffered from clinical mastitis. From those four cows, three remained infected with the same S. aureus strain despite antibiotic treatment.     

Epidemiology of S. aureus cross-infections in dermatological wards

Over a three-year period, 196 of 3115 patients admitted in a dermatological department became infected with S. aureus (6,2 %). 205 strains of S. aureus were isolated. Serologic typing, phage-typing and antibiotic sensitivity tests revealed 3 epidemic and 2 endemic strains. The 3 epidemic strains infected 24 patients: 12 from july to november 1972 were infected with a serotype 66438 S. aureus resistant to fusidic acid. 6 patients (male) were infected with a serotype III in february and march 1972; 8 patients were contaminated with a serotype 18 S. aureus from december 1973 to february 1974, after staying in a surgical department. Of the 2 endemic strains 1, phage-pattern 53/79, is non-typable by serologic-typing; this strain has been observed only in the dermatological department and 20 patients were infected with, from january to october 1974. The second endemic strain, phage-pattern 81/+ serotype I, cross-infected 16 patients during this three-year survey; 12 of them were admitted repeatedly. During this three-year survey, it could be proved that, at least, 1 out of 3 patients is infected with an epidemic or an endemic strain. We can suggest that the factors enhancing cross-infection in dermatological department are: the sex of patients (80 % were male); presence of a tween splitting enzyme by S. aureus promotes growth of Staphylococci on the skin; patients transfered from a department to another or repeatedly admitted are more often infected. But, as they are source of some outbreaks, they need special measures (asepsis and hygiene); cortico?ds or immunodepressors enhance cross-infection; antibiotics must not be only limited but varied too.     

Rapid detection of epidemic strains of methicillin-resistant Staphylococcus aureus

Fifty methicillin-resistant Staphylococcus aureus (MRSA) initial isolates obtained from patients hospitalized in the orthopedic clinic of the Frankfurt University Hospital and 150 methicillin-sensitive Staphylococcus aureus (MSSA) isolates were investigated in this study to determine whether the Slidex Staph-Kit is capable of differentiating between MRSA and MSSA owing to its unique performance characteristics. The Slidex Staph-Kit is a combined latex hemagglutination test designed to detect clumping factor, protein A, and a specific surface immunogen for S. aureus. Clumping factor-positive strains cause erythrocytes sensitized with fibrinogen to hemagglutinate, thereby resulting in visible red clumps. S. aureus strains deficient in clumping factor agglutinate latex particles sensitized with specific antibodies against surface proteins of S. aureus, thereby resulting in visible white clumps. Our results demonstrate that white clumping has a 99% specificity as well as a 98% positive predictive value for MRSA. Clumping factor-negative MRSA, which have been reported to occur in several countries, are epidemic in the Frankfurt area and account for 80% of all MRSA initial isolates in the orthopedic clinic of the Frankfurt University Hospital. Genotyping of all MRSA isolates by macrorestriction analysis of chromosomal DNA revealed that 83% of clumping factor-negative MRSA are closely related to the "southern-German" epidemic strain. This is the first study demonstrating the Slidex Staph-Kit's capability for identifying epidemic clumping factor-negative S. aureus strains as methicillin resistant even prior to antimicrobial susceptibility testing.     

Influence of substrate moisture on the occurrence of fungi in birds'' nests

Bacteriological examination of healthy school children and adults for Staphylococcus aureus by weekly swabbing of nose, throat and hands over extended periods demonstrated a general transition from persistent to transient carrier status between 10 and 20 years of age. Adult transient carriers were commoner among manual than office workers and frequently yielded biochemically atypical isolates, possibly because of acquired resistance to typical strains. Nasal carriage was commonest, but children frequently yielded the organism from both nose and throat.     

Incidence of nasal carriers of Staphylococcus aureus in and outside hospital environment and antibiotic sensitivity of isolated staphylococcus strains

This study was carried out on 100 nasal swabs collected from medical personnel (nurses and doctors) and patients inside hospital environment and also from 50 individuals outside hospital. The swabs were inoculated on different culture media for isolation of /staphylococci which were further identified as S. aureus either by classic bacteriologic methods or by one of rapid screening test of S. aureus. The isolated strains were tested for antibiotic sensitivity to some of B-Lactam antibiotics and to other antibiotics. The results showed that significantly higher percentage of coagulase + ve Staph. were isolated from newborn nursery (90%), operating theatre (71.4%) and hemodialysis unit (60%) than those isolated from intensive care unit, cancer chemotherapy, surgery, chest, internal medicine departments (25%, 26.6%, 31.2%, 33.3%, 50%) respectively. It also showed significant difference in isolation rate between persons at the hospital (patients, doctors and nurses) 44% and controls (normal population) 26%. Most isolates of coagulase + ve Staph. were resistant to penicillin G (93.2%), Streptomycin (77.3%), tetracycline (61.4%) and sensitive to cefamandole (95.4%). All coagulase+ve Staph. isolates were resistant to sulphonamide and methicillin and all sensitive to vancomycin.     

In vitro comparative activity (E test) of sparfloxacin and other 8 antimicrobial agents against bacteria isolated from patients with respiratory infections acquired in the community

Sparfloxacin is a new antimicrobial that, while maintaining a good activity against gram negative bacilli, has a better in vitro activity against gram positive bacteria such as S pneumoniae, intracellular pathogens and anaerobic bacteria. The aim of this work was to study the in vitro activity of sparfloxacin against bacteria isolated from patients with community acquired respiratory infections between October 1994 and January 1995. Using the E-test technique, we studied the susceptibility to sparfloxacin, ciprofloxacin, ampicillin, amoxicillin/clavulanic acid, cefuroxime, cefotaxime, erythromycin, methicillin and nalidixic acid of 50 strains of S pneumoniae, 50 strains of H. influenzae, 50 strains of S aureus and 50 strains of S pyogenes. Sparfloxacin was active against 100% of S pneumoniae, H influenzae and S pyogenes strains. Twenty two percent of S aureus strains were resistant and the MIC 90 was 12 micrograms/ml. Sparfloxacin showed the best in vitro activity against H influenzae and S aureus, a similar activity with ampicillin and cefotaxime against S pneumoniae and a similar activity with ampicillin but superior to all other studied antimicrobial against S pyogenes. It is concluded that sparfloxacin is a good antimicrobial for bacteria isolated from patients with respiratory infections.     

Induction and measurement of antisperm antibody responses in vitro

We did a statistical study of 294 strains of Staphylococcus aureus (S. aureus) isolated from skin infections during the period from January of 1989 to December of 1991 in the Department of Dermatology, Kansai Medical University Hospital. We especially examined methicillin-resistant S. aureus (MRSA) from the point of view of incidence, variety of skin infections with MRSA, coagulase type, phase type, and resistance against antimicrobial agents. The frequency of isolation of MRSA has been increasing. In 1991, the proportion of MRSA isolates among all S. aureus strains isolated from skin infections was 41.5%. MRSA was isolated most often from infectious decubitus. Coagulase type II and phage group NT (not typable) MRSA were most frequently isolated. The resistance of MRSA to OFLX and IMP/CS had remarkably increased. Notably, the resistance to MINO was low before 1991.     

Bronchoalveolar lavage or oropharyngeal cultures to identify lower respiratory pathogens in infants with cystic fibrosis

As collections of lower respiratory tract specimens from young children with cystic fibrosis (CF) are difficult, we determined whether oropharyngeal cultures predicted lower airway pathogens. During 1992-1994, 75 of 90 (83%) infants with CF diagnosed by neonatal screening had 150 simultaneous bronchoalveolar lavage (BAL) and oropharyngeal specimens collected for quantitative bacterial culture at a mean age of 17 months (range, 1-52). Ten children undergoing bronchoscopy for stridor served as controls. Total and differential cell counts and interleukin-8 concentrations were measured in BAL fluid. A subset of bacterial pathogens were typed by pulsed field gel electrophoresis. A non-linear relationship with inflammatory markers supported a diagnosis of lower airway infection when > or = 10(5) colony-forming units/ml were detected. This criterion was met in 47 (31%) BAL cultures from 37 (49%) children. Staphylococcus aureus (19%), Pseudomonas aeruginosa (11%), and Hemophilus influenzae (8%) were the major lower airway pathogens. In oropharyngeal cultures, S. aureus (47%), Escherichia coli (23%), H. influenzae (15%), and P. aeruginosa (13%) predominated. The sensitivity, specificity, and positive and negative predictive values of oropharyngeal cultures for pathogens causing lower respiratory infections were 82%, 83%, 41%, and 97%, respectively. When there was agreement between paired oropharyngeal and BAL cultures, genetic fingerprinting showed some strains of the same organism were unrelated. We conclude that oropharyngeal cultures do not reliably predict the presence of bacterial pathogens in the lower airways of young CF children.     

Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (1996)

The bacteria isolated from the patients with lower respiratory tract infections were collected by institutions located throughout Japan, since 1981. Ikemoto et al. have been investigating susceptibilities of these isolates to various antibacterial agents and antibiotics, and characteristics of the patients and isolates from them each year. Results obtained from these investigations are discussed. In 16 institutions around the entire Japan, 557 strains of presumably etiological bacteria were isolated mainly from the sputa of 449 patients with lower respiratory tract infections during the period from October 1996 to September 1997. MICs of various antibacterial agents and antibiotics were determined against 98 strains of Staphylococcus aureus, 93 strains of Streptococcus pneumoniae, 84 strains of Haemophilus influenzae, 84 strains of Pseudomonas aeruginosa (non-mucoid strains), 17 strains of Pseudomonas aeruginosa (mucoid strains), 31 strains of Moraxella subgenus Branhamella catarrhalis, 21 strains of Klebsiella pneumoniae etc., and the drug susceptibilities of these strains were assessed except for those strains that died during transportation. 1) S. aureus S. aureus strains for which MICs of oxacillin (MPIPC) were higher than 4 micrograms/ml (methicillin-resistant S. aureus) accounted for 67.3%. The frequency of the drug resistant bacteria increased comparing to the previous year's 52.7%. Arbekacin (ABK) and vancomycin (VCM) showed the highest activities against both S. aureus and MRSA with MIC80s of 1 microgram/ml. 2) S. pneumoniae Imipenem (IPM) and panipenem (PAPM) of carbapenems showed the most potent activities with MIC80s of 0.063 microgram/ml. Faropenem (FRPM) showed the next potent activity with MIC80 of 0.125 microgram/ml. The other drugs except erythromycin (EM), clindamycin (CLDM) and tetracycline (TC) were active against S. pneumoniae tested with MIC80s of 8 micrograms/ml or below. 3) H. influenzae The activities of all drugs were potent against H. influenzae tested with MIC80s of 4 micrograms/ml or below. Cefotiam (CTM), cefmenoxime (CMX), cefditoren (CDTR) and ofloxacin (OFLX) showed the most potent activities with MIC80s of 0.063 microgram/ml. 4) P. aeruginosa (mucoid strains) Tobramycin (TOB) showed the most potent activity against P. aeruginosa (mucoid strains) with MIC80 of 1 microgram/ml. Ceftazidime (CAZ), cefsulodin (CFS), IPM, gentamicin (GM), ABK and ciprofloxacin (CPFX) showed the next potent activities, with MIC80s of 2 micrograms/ml. The MIC80s of the other drugs ranged from 4 micrograms/ml to 16 micrograms/ml. 5) P. aeruginosa (non-mucoid strains) TOB and CPFX showed the most potent activities against P. aeruginosa (non-mucoid strains) with MIC80s of 1 microgram/ml. The MIC80s of piperacillin (PIPC) and cefoperazone (CPZ) were 16 micrograms/ml in 1995, and they were 64 micrograms/ml in 1996. 6) K. pneumoniae All drugs except ampicillin (ABPC) were active against K. pneumoniae. CMX, cefpirome (CPR), cefozopran (CZOP) and carumonam (CRMN) showed the most potent activities against K. pneumoniae with MIC80s of 0.125 microgram/ml. The MIC80s of the other drugs ranged from 0.25 microgram/ml to 2 micrograms/ml. 7) M.(B) catarrhalis Against M.(B.) catarrhalis, all drugs showed good activities with MICs of 4 micrograms/ml or below. IPM and minocycline (MINO) showed the most potent activities with MICs of 0.063 microgram/ml. Also, we investigated year to year changes in the characteristics of patients, their respiratory infectious diseases, and the etiology. Patients' backgrounds were examined for 557 isolates from 449 cases. The examination of age distribution indicated that the proportion of patients with ages over 60 years was 71.0% of all the patients showing a slight increase over that in 1994. Proportions of diagnosed diseases were as follows: Bacterial pneumonia and chronic bronchitis were the most frequent with 35.9% and 30.3% respectively. They were followed by bronchiectasis with a proportion of 10.