Outbreak of multiresistant non-encapsulated Haemophilus influenzae infections in a pulmonary rehabilitation centre

Nosocomial Outbreak of Upper Respiratory Tract Infection With β-Lactamase-Negative Ampicillin-Resistant Nontypeable Haemophilus influenzae

OBJECTIVETo describe the epidemiologic features of an outbreak of an acute respiratory tract infection (ARI) caused by β-lactamase-negative ampicillin-resistant (BLNAR) nontypeable Haemophilus influenzae (NTHi) in an acute-care ward.DESIGNCross-sectional case-control study.SETTINGAn acute-care ward (ward A) in a general hospital of Kochi in western Japan.METHODSPatients who shared a room with an index patient and all staff in ward A were screened and followed from July 1 to August 31, 2015. Sputum or throat swab samples were collected from participants and tested by culture and polymerase chain reaction (PCR). The association between detected pathogens and ARI development among all participants was examined. A case-control study was conducted to identify risk factors for disease.RESULTSIn total, 78 participants, including the index patient, were enrolled. Of all participants, 27 (34.6%) developed mild respiratory symptoms during a 3-week period: 24 were diagnosed as upper respiratory tract infections, and 3 were diagnosed as lower respiratory tract infections. The presence of BLNAR NTHi was confirmed in 13 participants, and multilocus sequence typing demonstrated that these isolates belonged to sequence type 159. All isolates showed identical pulsed-field gel electrophoresis patterns. The presence of BLNAR NTHi was strongly associated with ARI development, whereas viruses were not associated with the disease. Multivariate analyses demonstrated that a history of contact with the index patient was independently associated with ARI caused by BLNAR NTHi.CONCLUSIONSBLNAR NTHi has the potential to cause upper respiratory tract infections among adults and to spread rapidly in hospital settings.Infect Control Hosp Epidemiol 2018;39:652-659.

An outbreak of infections caused by non-typeable Haemophilus influenzae in an extended care facility

Nosocomial outbreaks of infection due to non-typeable Haemophilus influenzae (NTHi) are rarely described. There are a few published reports that suggest that elderly patients with underlying pulmonary disease are at risk and that person-to-person spread is key to disease transmission. During the summer months of 2005, we documented an outbreak of NTHi infections in a Veterans Affairs nursing home. Thirteen patients developed conjunctivitis or lower respiratory infection involving a beta-lactamase-negative biotype III NTHi isolate, with an indistinguishable SmaI macrorestriction pattern. Patients were elderly males usually with underlying cardiac and pulmonary disease. A case-control study failed to demonstrate any specific significant risk factor for NTHi infection and there was no evidence of spatial clustering of cases within the nursing home. A random throat culture survey involving nursing home patients during the outbreak showed that only one of 19 persons was colonized with NTHi. The outbreak concluded following appropriate treatment and an emphasis on universal and respiratory droplet precautions. All patients recovered and a specific inciting event for the outbreak was never defined. Literature review revealed a spectrum of responses to nosocomial NTHi infections and a lack of consensus regarding the infection control approach towards NTHi outbreaks.

Variable number of tandem repeats in clinical strains of Haemophilus influenzae

An algorithm capable of identifying short repeat motifs was developed and used to screen the whole genome sequence available for Haemophilus influenzae, since some of these repeats have been shown to affect bacterial virulence. Various di- to hexanucleotide repeats were identified, confirming and extending previous findings on the existence of variable-number-of-tandem-repeat loci (VNTRs). Repeats with units of 7 or 8 nucleotides were not encountered. For all of the 3- to 6-nucleotide repeats in the H. influenzae chromosome, PCR tests capable of detecting allelic polymorphisms were designed. Fourteen of 18 of the potential VNTRs were indeed highly polymorphic when different strains were screened. Two of the potential VNTRs appeared to be short and homogeneous in length; another one may be specific for the H. influenzae Rd strain only. One of the primer sets generated fingerprint-type DNA banding patterns. The various repeat types differed with respect to intrinsic stability as well. It was noted for separate colonies derived from a single clinical specimen or strains passaged for several weeks on chocolate agar plates that the lengths of the VNTRs did not change. When several strains from different patients infected during an outbreak of lung disease were analyzed, increased but limited variation was encountered in all VNTR sites analyzed. One of the 5-nucleotide VNTRs proved to be hypervariable. This variability may reflect the molecular basis of a mechanism used by H. influenzae bacteria to successfully colonize and infect different human individuals.

Haemophilus influenzae infections in adults: a pathogen in search of respect

Despite the success of Haemophilus influenzae type b vaccines in preventing bacterial disease in children, H influenzae remains a common pathogen in adult patients in the United States and Europe. At least half of invasive H influenzae infections are caused by nontypable strains. The spectrum of diseases includes sinusitis, pneumonia, otitis media, epiglotitis, and meningitis. An etiologic diagnosis is most reliably established by positive cultures from a normally sterile site. Although resistance to ampicillin and amoxicillin has steadily increased in clinical H influenzae isolates during the past two decades, a variety of other antimicrobial agents are available for the treatment of infections caused by this bacterium.

Infections and antibiotic resistance in nursing homes

Infections occur frequently in nursing home residents. The most common infections are pneumonia, urinary tract infection, and skin and soft tissue infection. Aging-associated physiologic and pathologic changes, functional disability, institutionalization, and invasive devices all contribute to the high occurrence of infection. Antimicrobial agent use in nursing homes is intense and usually empiric. All of these factors contribute to the increasing frequency of antimicrobial agent-resistant organisms in nursing homes. Programs that will limit the emergence and impact of antimicrobial resistance and infections in nursing homes need to be developed.

Antibiotic susceptibility of 206 Haemophilus influenzae isolates collected from children in central Italy

Susceptibility of 206 H. influenzae isolates was evaluated by disk diffusion method for 11 antimicrobial agents. No isolates were found to be resistant to third-generation cephalosporins, amoxicillin+clavulanic acid, gentamicin and ciprofloxacin. Four untypable isolates (1.9%) were beta-lactamase producing ampicillin-resistant; one of these was also resistant to chloramphenicol. The rate of resistance against rifampin was 0.5 percent.

Prospective epidemiological study of invasive Haemophilus influenzae disease in adults

The incidence and characteristics of invasive Haemophilus influenzae disease were studied in 43 adult patients admitted to the acute care hospitals in El Vallés County (Barcelona, Spain) between January 1987 and June 1992. The annual incidence of Haemophilus influenzae disease was 1.2 per 100,000 inhabitants. Pneumonia occurred in 24 patients, meningitis in five, intraabdominal infections in three, obstetric infections in two, epiglottitis in two and cellulitis in one. In six patients the source of infection was unknown. Ten (23%) of the infections were hospital acquired. Underlying conditions were diagnosed in 30 (70%) patients. Nontypeable Haemophilus influenzae strains predominated in all adult age groups. Sixty-one percent of type b and 34% of nontypeable strains were ampicillin resistant (p = 0.08). Multiple antibiotic resistance was also high among type b (53%) and nontypeable (18%) strains. The mortality rate was significantly higher in patients with pneumonia, bacteremia from an unidentified focus or shock at presentation.

A nosocomial outbreak due to non-encapsulated Haemophilus influenzae: analysis of plasmids coding for antibiotic resistance

An outbreak of infections with non-encapsulated Haemophilus influenzae, resistant to ampicillin, chloramphenicol, sulphonamide and tetracycline involved 13 elderly patients and three nurses on acute admission and care of the elderly wards. Thirty-two isolates were found to be indistinguishable on analysis of biotype, antibiogram, serotype and major outer membrane proteins (MOMP). Plasmids could not be identified in the original isolates but after mating with a Rec A H. influenzae recipient, the resultant transconjugates were found to harbour either a 72 kilobase pair (kB) plasmid coding for resistance to chloramphenicol, ampicillin, sulphonamide and tetracycline or a 65 kB plasmid coding for resistance to chloramphenicol, ampicillin and sulphonamide. Both plasmids yielded virtually indistinguishable restriction digest patterns. This suggests that the tetracycline resistance gene (Tc gene) is a non-essential component of one basic plasmid responsible for the multiple antibiotic resistances seen in the strains recovered during the outbreak. This illustrates the value of plasmid profiles to compare strains of non-encapsulated H. influenzae, and suggests that plasmid restriction enzyme analysis is critical.

Nosocomial transmission of disease caused by nontypeable strains of Haemophilus influenzae

PURPOSE

The authors evaluated a geographic and temporal cluster of lower respiratory tract infections due to unencapsulated (serologically nontypeable) Haemophilus influenzae to determine whether this event represented the transmission of a single clone.

METHODS AND MATERIALS

H influenzae was recovered from eight patients at a nursing home and from three patients in an adjacent acute care hospital. Serotypes, biotypes, outer membrane protein profiles, and multilocus enzyme genotypes were determined to characterize bacterial isolates. Patient records were retrospectively examined to determine clinical and epidemiologic characteristics.

RESULTS

During a 10-day period in September 1991, lower respiratory tract infections caused by H influenzae were diagnosed in four patients residing in a single nursing home unit. Oropharyngeal cultures from four of seven asymptomatic roommates of these patients also grew H influenzae. During the month before and after the nursing home cluster of cases, four other individuals in acute care areas of the hospital had positive sputum cultures for H influenzae. Three of these latter specimens were also available for analysis. All H influenzae isolates were unencapsulated and beta-lactamase-negative. Eight of the nine isolates from the nursing home patients (two morphologically distinct colony types of H influenzae were isolated from one case) had a single outer membrane protein profile arbitrarily designated as X and a single multilocus enzyme genotype arbitrarily designated as A. In contrast, none of the isolates from the acute care cases had this profile (P < or = 0.02; two-tailed Fisher's exact test). The isolates obtained from two of the patients in acute care areas had an outer membrane protein profile arbitrarily designated as Y and a single multilocus enzyme genotype designated as B. These two patients were contemporaneously hospitalized in adjacent intensive care unit cubicles. The remaining isolates displayed an outer membrane protein profile arbitrarily designated as W. All roommates of the four patients in the nursing home were administered oral rifampin 600 mg daily for 4 days. H influenzae was not recovered from follow-up oropharyngeal cultures obtained 1 week after the completion of therapy. No beta-lactamase-negative H influenzae were identified in this unit during the subsequent 9 months.

CONCLUSION

This study furnishes strong evidence for the nosocomial transmission of a clone of unencapsulated H influenzae in a nursing home unit. Epidemiologic data showed temporal and geographic clustering of respiratory tract infections and colonization by H influenzae. Outer membrane protein profiles and multilocus enzyme genotype analysis indicated that seven of eight patients at the nursing home carried a single clone of unencapsulated H influenzae. Laboratory and epidemiologic data also demonstrated the presence, and possible nosocomial transmission, of a second clone of unencapsulated H influenzae in a physically separate area of the hospital. Finally, although a causal relationship is not proven, the outbreak ended following the administration of rifampin prophylaxis of asymptomatic carriers.

Polymerase chain reaction-based strain characterization of noncapsulate Haemophilus influenzae

A polymerase chain reaction-based typing method for noncapsulate Haemophilus influenzae was developed. Randomly amplified polymorphic DNA fingerprints were generated from boiled supernatants prepared directly from bacterial colonies without the need for DNA extraction. The technique was applied to isolates obtained during putative outbreaks of chest infection and validated by comparison with sodium dodecyl sulfatepolyacrylamide gel electrophoresis analysis of outer membrane protein-enriched preparations and rRNA gene restriction analysis. There was complete concordance between the three techniques. The results show that randomly amplified polymorphic DNA analysis provides a highly discriminatory method of characterizing strains of noncapsulate H. influenzae which is eminently suitable as an epidemiological tool for the rapid investigation of outbreaks of infection.

Current trends in bacterial respiratory pathogens

The relationship of virulence and antimicrobial susceptibility with morbidity due to bacterial respiratory pathogens is complex and evolving. Ultimately, decreasing the incidence of pneumonia due to bacterial pathogens will be dependent on successful preparation and distribution of effective vaccines. Until effective vaccines are widely available, control of a majority of respiratory infections will depend on promotion of rational therapeutic strategies. Though limited to a few specific serotypes and strains, changes in virulence of bacterial respiratory pathogens have been noted. Co-infections due to multiple respiratory pathogens may increase morbidity; however, the epidemiology of co-infections is not clear. Relationships between respiratory viruses and bacteria may exist that increase virulence of both agents, but information regarding these relationships awaits further investigation. Resistance of respiratory pathogens to the more commonly used antimicrobials, such as penicillin, erythromycin, chloramphenicol, and cotrimoxazole, is being documented globally with increasing frequency. The evolution of antimicrobic resistance, especially among strains of Streptococcus pneumoniae, the most common and deadly agent of lower respiratory tract infections, provides impetus to develop and promote effective pneumococcal vaccines and to search for new and effective antimicrobials.

Antibiotic resistance in Haemophilus influenzae: mechanisms, clinical importance and consequences for therapy

Invasive and non-invasive infections caused by Haemophilus influenzae are frequently diagnosed in children below the age of 5 years. The treatment of choice for these infections was ampicillin. However, since the early 1970s the increasing prevalence of resistance to ampicillin and other antibiotics has necessitated major changes in antibiotic therapy. This article summarizes some of the important clinical features of diseases caused by H. influenzae. The epidemiology, the problems with in vitro susceptibility testing and the mechanisms of resistance to major antibiotics are reviewed. The consequences of antibiotic resistance for the treatment of diseases caused by H. influenzae are discussed.

Characterization of noncapsulate Haemophilus influenzae by whole-cell polypeptide profiles, restriction endonuclease analysis, and rRNA gene restriction patterns

Thirty-four clinical isolates of noncapsulate Haemophilus influenzae representing isolates with either related or dissimilar patterns of whole-cell polypeptide profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were further characterized by restriction enzyme analysis (REA) and rRNA gene restriction patterns. Total cellular DNA was extracted by a rapid, microcentrifuge-scale method and digested with BamHI, which gave a pattern of about 18 discrete bands. This confirmed the five closely related groupings suggested by SDS-PAGE. Isolates dissimilar by SDS-PAGE were also distinguishable by REA. However, there was no correlation between the degrees of similarity estimated from whole-cell polypeptide profiles and those obtained from REA for the dissimilar isolates. Therefore, inferences of genetic relatedness made on the basis of these data should be interpreted with caution. rRNA gene restriction patterns also confirmed the groupings suggested by the other two techniques. We conclude that the three methods were highly discriminatory and that whole-cell polypeptide patterns or REA with BamHI would be appropriate techniques for epidemiological studies of noncapsulate H. influenzae.

The use of oral antibiotics in daily clinical practice

In the treatment of infectious diseases in daily clinical practice, the physician is faced with a wide choice of antibiotics. Rational antibiotic use requires knowledge of the pathogens causing disease at that site, and the prevalence of resistance. In outpatient respiratory tract infection, for example, 3 pathogens, Branhamella (Moraxella) catarrhalis, Haemophilus influenzae and Streptococcus pneumoniae, predominate, beta-Lactamase production by the first 2 is a significant factor in antibiotic selection for respiratory tract infection. Empirical antibiotics are selected for efficacy, cost-effectiveness, safety and patient compliance.

Cross-infection by non-encapsulated Haemophilus influenzae

From October, 1988, to January, 1989, 18 patients admitted to an acute medical chest ward were infected with an ampicillin-resistant beta-lactamase-producing strain of Haemophilus influenzae. All 18 isolates were non-encapsulated strains of biotype III and showed identical cell envelope protein profiles, as judged by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The organism was not isolated from repeated environmental samples but there was strong circumstantial evidence that a spirometer was a common iatrogenic source of the cross-infection.