An outbreak of Streptococcus pneumoniae in an Italian nursing home

AN


INTRoDUcTIoN
Pneumonia is sometimes referred to as the forgotten killer.The World Health Organization estimates that lower respiratory tract infections are the most common infectious cause of death in the world (the third most common cause overall), with almost 3.5 million deaths yearly [1].Furthermore, an estimated 1.6 million people die of Invasive Pneumococcal Disease (IPD) annually, including one million children under five years of age [2].Severe communityacquired pneumonia is the most common cause of death from infection in developed countries: Streptococcus pneumoniae accounts for at least 40% of such cases in adults [3], even if a specific surveillance is difficult to achieve, leading to under diagnosis and poor knowledge of definite areas.In Europe surveillance of invasive pneumococcal disease, including meningitis, pneumonia, bacteraemia and sepsis is now provided by the European Center for Disease

AN OuTBREAk Of STREPTOCOCCuS PNEumONIAE
Control (ECDC); in 2012 the overall reported confirmed case rate was 4.28 per 100 000 [4], comparable with the previous two years, and higher notification rates were observed in Nordic countries.IPD is predominantly found in adults aged 65 or over, followed by young children under five years and adults aged between 45 and 64 years.In Italy, the 2013 rate of IPD was of 1,64 per 100.000 and it is slightly increasing over years [5].Pneumococcus is mainly transmitted by direct contact with contaminated respiratory secretions between household members, infants, and children; affected patients are generally not regarded as highly contagious, and respiratory isolation in both community and hospital settings is rarely indicated; moreover, airway colonisation by pneumococci is readily detectable in about 10% of healthy adults, 20-40% of healthy children are carriers, and more than 60% of infants and children in day-care settings can be carriers [6].
Community-acquired pneumonia that is severe enough to require hospitalization is associated with excess mortality over the subsequent years among survivors, [7][8][9] even among young people without underlying disease [8].Admission to the hospital for community-acquired pneumonia is also costly, especially if care in an intensive care unit (ICU) is required [10][11].
Streptococcus pneumoniae occurs sporadically in most cases; anyway, outbreaks may verify, in particular in closed communities and in the pre-vaccine era [12][13].In this report we describe an outbreak of pneumococcal disease in a nursing home for elders in valle d'Aosta region, Italy.

METHoDS
The outbreak occurred in a nursing home for elders in Aosta, the main town of the Alpine italian Region Valle d'Aosta, northern Italy.This residential structure can accommodate up to 21 guests (19 patients in residential care and two in semi-residential care).The nursing home has got both two beds rooms and single bed rooms, and one dining room.At outbreak onset (April 2014) 20 patients were present, 12 females (mean age: 86 years; range 70-98) and 8 males (mean age: 83 years; range 77-95); none them had been vaccinated against Streptococcus pneumoniae.
The outbreak involved 12 out of 20 guests, and is summarized in Figure 1:   picture and was therefore discharged and treated with oral antibiotics.• The remaining eight guests remained asymptomatic during the epidemic period, received anti pneumococcal conjugated vaccine soon after but no antibiotic prophylaxis; next, two nursing-home workers and some of their relatives reported symptoms of airway infection, without further complications.Seven of eight patients were clustered in the Geriatry ward, the eighth, suffering from significant hypoxemic respiratory failure, was admitted in a single room in the Infectious Diseases ward.The average age of the patients admitted was 84,2 years (range: 70-95).All patients were bedridden with encephalopathies based, vascular and/or degenerative significant cognitive impairment.Seven of eight patients had a positive Streptococcus pneumoniae urine test; by contrast, blood cultures were performed in three cases, all negative.Five patients were treated with third generation intravenous cephalosporin (one of them had in association with oral macrolide), three patients were treated with intravenous levofloxacin followed by early oral switch.Therapy was effective, with full recovery in all cases and an average hospital stay of 7.3 days.
To foster outbreak interruption in the nursing

DIScUSSIoN
Pneumococcus outbreaks are increasingly unfrequent, especially since progressive diffusion of vaccine, even in countries, like Italy, with a low and scattered vaccine coverage in adults [14].In particular, we found only 12 published outbreaks of serious pneumococcal disease in closed settings, including elderly care residential settings, in a four decades period [15,16].In recent years, largest outbreaks occurred in Canada, with hundreds of cases reported [17], and in Japan, with 15 cases reported in 2009 [18].Anyway, at our knowledge, this is the first reported outbreak in a nursing home in Italy; at this regard , our finding is of concern, given progressive population ageing in Italy and wide distribution of thousand nursing homes over all the national territory.
The outbreak we describe has been clinically significant, affecting more than half of the nursing-home guests, causing several AN OuTBREAk Of STREPTOCOCCuS PNEumONIAE hospital admissions and two probably related deaths.This is not surprising; Pneumococcus pneumonia is a severe disease, and results in the death of 20 to 40% of elderly patients [7]: unfortunately, in our case the lack of blood cultures isolates didn't allow analysis and susceptibility patterns of the involved strains.The outbreak causes are clear enough; Streptococcus pneumoniae frequently colonizes the upper respiratory tract: as such it is not considered a typical communicable disease; however special conditions of overcrowding and promiscuity in gated communities allow to overcome the critical threshold for epidemic spread of the germ, both in small facilities as our and in much larger ones, as previously described [15].At this regard, even if a wide range of control measures were started, it is likely that the most useful had been halting new admissions and limiting accesses form both visitors and unnecessary employees; recently, the early mobility bundle showed efficacy in reducing the incidence of hospitalacquired pneumonia [19], and it should be implemented also, if not especially, in long-term care settings.In valle d'Aosta region a network of more than forty small nursing homes was created (15 to 40 guests in most cases), with the aim of hosting elders as close as possible to their family and social behaviours.Side effect of such policy is in the difficulty of sharing health practices of common interest; such as, typically, hygiene protocols and behaviours: in valle d'Aosta this is even more challenging since nursing home management belongs to different non-healthcare organizations.
In conclusion, nursing homes concentrate high risk elders and therefore must be considered at high risk for dangerous infective outbreaks.Hygiene and surveillance protocols are mandatory in nursing homes and their sharing by the whole network of nursing homes in a given territory should be ensured by the local health authorities.Finally, anti pneumococcal vaccination by conjugate vaccine in the instituzionalized elders should be a priority, especially since the efficacy of polysaccharide conjugated vaccine in adults against pneumococcal pneumonia has been demonstrated [20].

Figure 1 :
Figure 1: epidemic curve , Streptococcus pneumoniae outbreak in a nursing home Epidemiology Biostatistics and Public Health -2015, Volume 12, Number 3